id int64 39 79M | url stringlengths 31 227 | text stringlengths 6 334k | source stringlengths 1 150 ⌀ | categories listlengths 1 6 | token_count int64 3 71.8k | subcategories listlengths 0 30 |
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77,555,170 | https://en.wikipedia.org/wiki/NGC%206308 | NGC 6308 is a large intermediate spiral galaxy in the constellation of Hercules. Its velocity with respect to the cosmic microwave background is 8797 ± 3 km/s, which corresponds to a Hubble distance of 129.74 ± 9.08 Mpc (∼423 million light-years). It was discovered by German astronomer Albert Marth on 6 June 1863.
NGC 6308 has been identified as field galaxy, i.e. it does not belong to a cluster or group.
One supernova has been observed in NGC 6308: SN 2023oyz (type Ic, mag 20.4214) was discovered by the Zwicky Transient Facility on 9 August 2023.
See also
List of NGC objects (6001–7000)
References
External links
6308
059807
+04-40-021
10747
17099+2326
Hercules (constellation)
18630606
Discoveries by Albert Marth
Intermediate spiral galaxies | NGC 6308 | [
"Astronomy"
] | 193 | [
"Hercules (constellation)",
"Constellations"
] |
77,555,922 | https://en.wikipedia.org/wiki/NGC%206685 | NGC 6685 is an elliptical galaxy in the constellation of Lyra. Its velocity with respect to the cosmic microwave background is 6432 ± 37 km/s, which corresponds to a Hubble distance of 94.87 ± 6.68 Mpc (∼310 million light-years). It was discovered by American astronomer Edward Swift on 29 May 1887.
Supernovae
Two supernovae have been observed in NGC 6685:
SN 2006bq (type Ia, mag 15.8) was discovered by Tim Puckett and A. Pelloni on 23 April 2006.
SN 2023ndu (type Ia, mag 18.4555) was discovered by the Automatic Learning for the Rapid Classification of Events (ALeRCE) on 14 July 2023.
See also
List of NGC objects (6001–7000)
References
External links
6685
062220
+07-38-015
11317
Lyra
18870529
Discoveries by Edward Swift
Elliptical galaxies | NGC 6685 | [
"Astronomy"
] | 198 | [
"Lyra",
"Constellations"
] |
77,555,928 | https://en.wikipedia.org/wiki/Exidia%20zelleri | Exidia zelleri is a species of fungus in the family Auriculariaceae. Basidiocarps (fruit bodies) are gelatinous, pale violaceous grey to grey-brown, button-shaped at first then coalescing and becoming irregularly effused. It grows on dead branches of broadleaved trees and is known from north-western North America.
Taxonomy
The species was first described in 1920 from Oregon by mycologist Curtis Gates Lloyd.
Description
The basidiocarps of E. zelleri are gelatinous, button-shaped to top-shaped and attached to the wood at a point, sometimes coalescing to form effused, irregular masses up to 8 cm across. pale violaceous grey to grey brown, darkening with age. The surface is sparsely to densely covered in small papillae (pimples).
Microscopic characters
The translucent hyphae are thin-walled and form clamp connections. Basidia are elliptical and consist of four longitudinally septate cells. Basidiospores are allantoid (sausage shaped), 16 to 19 by 5 to 6 μm, with thin, smooth walls.
Similar species
Fruit bodies of Exidia crenata and Exidia recisa also occur on broadleaved trees in North America, but are typically reddish to orange-brown and lack papillae on the surface. Exidia glandulosa has papillae, but is typically blackish brown to black.
Distribution and habitat
Exidia zelleri was originally described from Oregon and has also been recorded from California and British Columbia. It was originally collected on dead wood of Sambucus, but has subsequently been reported on other broadleaved trees.
References
Auriculariales
Fungi of North America
Fungus species
Taxa named by Curtis Gates Lloyd
Fungi described in 1920 | Exidia zelleri | [
"Biology"
] | 377 | [
"Fungi",
"Fungus species"
] |
77,556,396 | https://en.wikipedia.org/wiki/NGC%205898 | NGC 5898 is an elliptical galaxy in the constellation of Libra. Its velocity with respect to the cosmic microwave background is 2301 ± 13 km/s, which corresponds to a Hubble distance of 33.93 ± 2.38 Mpc (∼111 million light-years). It was discovered by German-British astronomer William Herschel on 21 May 1784.
One supernova has been observed in NGC 5898: SN 2023mkt (type Ia, mag 18.2) was discovered by the Automatic Learning for the Rapid Classification of Events (ALeRCE) on 7 July 2023.
NGC 5903 group
According to A. M. Garcia, NGC 5898 is part of the five member NGC 5903 Group (also known as LGG 398). The other four galaxies are NGC 5903, IC 4538, ESO 514–3, and ESO 582–12.
Image gallery
See also
List of NGC objects (5001–6000)
References
External links
5898
054625
-04-36-006
Libra (constellation)
17840521
Discoveries by William Herschel
Elliptical galaxies
UGCA objects
514- G 002 | NGC 5898 | [
"Astronomy"
] | 245 | [
"Libra (constellation)",
"Constellations"
] |
77,556,723 | https://en.wikipedia.org/wiki/NGC%203087 | NGC 3087 is an elliptical galaxy in the constellation of Antlia. Its velocity with respect to the cosmic microwave background is 2987 ± 30 km/s, which corresponds to a Hubble distance of 44.05 ± 3.13 Mpc (∼144 million light-years). It was discovered by British astronomer John Herschel on 2 February 1835.
One supernova has been observed in NGC 3087: SN 2023mdv (type Ia, mag 18.3) was discovered by ATLAS on 29 June 2023.
NGC 3038 Group
According to A. M. Garcia, NGC 3087 is part of the six member NGC 3038 Group (also known as LGG 184). The other five galaxies are NGC 3038, NGC 3120, IC 2532, ESO 373–21, and ESO 373–26.
See also
List of NGC objects (3001–4000)
References
External links
3087
028845
-06-22-005
Antlia
18350202
Discoveries by John Herschel
Elliptical galaxies
374- G 015 | NGC 3087 | [
"Astronomy"
] | 222 | [
"Antlia",
"Constellations"
] |
77,556,775 | https://en.wikipedia.org/wiki/Tritium%20breeding%20module | A tritium breeding module or TBM is a component of a fusion reactor that produces tritium.
ITER will have four easily removable TBMs in order to test various material combinations in order to develop the breeding process.
See also
Breeding blanket
References
ITER
Fusion reactors | Tritium breeding module | [
"Chemistry"
] | 56 | [
"Nuclear fusion",
"Fusion reactors"
] |
77,556,926 | https://en.wikipedia.org/wiki/Diflufenican | Diflufenican (sometimes called DFF) is a herbicide used to control weeds including wild radish and wild turnip weeds or suppress capeweed, crassula, marshmallow or shepherd's purse, in clover pasture, lupins, lentils or field peas. It has seen use in Australia, Europe, and in Feb 2024 registered in North America by the PMRA, EPA registration pending, for use on soybean and corn.
376 tonnes of diflufenican active ingredient were used in the United Kingdom in 2020.
Discovery
Diflufenican was discovered with a common intermediate method (CIM), and trialled in England and France between 1981 and 1983. A simple intermediate is reacted and recombined. Diflufenican derives from 2-chloronicotinic acid, one product replaced the chlorine with a phenoxy group, one receives an aniline group, and then both are recombined into DFF.
Toxicology
The Australian Acceptable Daily Intake for diflufenican is set at 0.2 mg/kg/day, based on the NOEL of 16.3 mg/kg/day. With an oral rat of >5000 mg/kg, diflufenican is not toxic to mammals, nor to honeybees.
By inhalation, the air LC50 is 2.34 mg/L, for rats. It is not irritating to the skin and eyes, tested on rabbits. In dogs over 90 days, a NOEL of 1000 mg/kg daily was found. By the Ames Test, it is non-mutagenic.
To birds, diflufenican is not toxic. LD50 of >2150 mg/kg (quail), >4000 mg/kg (mallard ducks). For fish, the LC50 is 56–100 mg/L (rainbow trout), 105 mg/L (carp). DFF does not inhibit the growth of algae. Non-toxic to earthworms.
Environmental fate
Diflufenican has high persistence in soil but has low mobility, and low bioaccumulative potential. It is toxic to aquatic life. (See toxicology section for details).
Diflufenican rapidly metabolises in cereals to carbon dioxide via nicotinamide and nicotinic acid, and leaves no detectable residue after 200–250 days. In soil, similar degradation to CO2 is seen, with a half life of 15 to 30 weeks.
Effect and mechanism
Targeted weeds display bleaching and chlorotic spotting, followed by pink and purple foliage and necrosis. Symptoms typically begin 3–4 days after application. DFF's residual activity may last 8 weeks.
Diflufenican inhibits carotenoid synthesis, without which photosynthesis begins to fail and the plant is vulnerable to damage from sunlight, causing growth cessation and necrosis. It is absorbed by germinating seedlings. Usually applied at 125–250 g/ha pre-emergence or shortly after, often with other cereal herbicides.
Diflufenican is a Group F, (Australia), F1 (global) or Group 12 (numeric) resistance class herbicide.
Regulations
Diflufenican is registered in the United Kingdom and the European Union, for professional and amateur use. It is also approved in New Zealand.
Applications
Diflufenican is often applied at 50–100 g/ha, or lower if part of a herbicide mixture, e.g. as little as 9 g/ha with bromoxynil.
List of targeted weeds
Diflufenican has shown control over: wild radish, wild turnip, turnip weed, multiply herbicide resistant waterhemp (applied pre-emergence), hedge mustard, Indian hedge mustard, charlock, deadnettle, prickly lettuce, pheasant's eye, Galium aparine, ivy-leaved speedwell and Veronica persica; and suppression of capeweed, crassula, night-scented stock, marshmallow, corn gromwell, chickweed, hyssop loosestrife, Skeleton weed, speedwell, amsinckia, Paterson's curse, rough poppy, sorrel, toad rush, stinging nettle and shepherd's purse.
List of co-used pesticides
Diflufenican has been sold in formulations containing (not limited to): isoproturon, ioxynil, mecoprop, bromoxynil, diclofop-methyl, and pendimethalin. Furthermore, compatibility is reported with: simazine, alpha cypermethrin, metribuzin and quizalofop, in addition to compatibility with most grass herbicides.
List of crops applied to
Diflufenican has been applied to crops, including: wheat, barley, field peas, lentils, lupins and oilseed poppy.
Tradenames
Diflufenican
DFF
Brodal
References
External links
Anilides
Herbicides
Trifluoromethyl compounds
Nicotinamides
Fluorobenzene derivatives
Phenol ethers | Diflufenican | [
"Biology"
] | 1,078 | [
"Herbicides",
"Biocides"
] |
77,556,936 | https://en.wikipedia.org/wiki/Eogeranoides | Eogeranoides is an extinct monospecific and dubious genus of ratite. The type and only known species, Eogeranoides campivagus, described in 1969 by Joel Cracraft, is represented by several fragmentary extremities of leg bones, collected in the Early Eocene Foster Gulch locality of the Willwood Formation in Wyoming. Highly fragmentary, the genus is poorly defined and Gerald Mayr proposed in 2016 that it represent a junior synonym of Paragrus prentici.
References
Struthioniformes
Eocene birds of North America
Fossil taxa described in 1969
Eocene genera
Prehistoric bird genera
Nomina dubia | Eogeranoides | [
"Biology"
] | 135 | [
"Biological hypotheses",
"Nomina dubia",
"Controversial taxa"
] |
77,557,393 | https://en.wikipedia.org/wiki/Normalization%20%28machine%20learning%29 | In machine learning, normalization is a statistical technique with various applications. There are two main forms of normalization, namely data normalization and activation normalization. Data normalization (or feature scaling) includes methods that rescale input data so that the features have the same range, mean, variance, or other statistical properties. For instance, a popular choice of feature scaling method is min-max normalization, where each feature is transformed to have the same range (typically or ). This solves the problem of different features having vastly different scales, for example if one feature is measured in kilometers and another in nanometers.
Activation normalization, on the other hand, is specific to deep learning, and includes methods that rescale the activation of hidden neurons inside neural networks.
Normalization is often used to:
increase the speed of training convergence,
reduce sensitivity to variations and feature scales in input data,
reduce overfitting,
and produce better model generalization to unseen data.
Normalization techniques are often theoretically justified as reducing covariance shift, smoothing optimization landscapes, and increasing regularization, though they are mainly justified by empirical success.
Batch normalization
Batch normalization (BatchNorm) operates on the activations of a layer for each mini-batch.
Consider a simple feedforward network, defined by chaining together modules:
where each network module can be a linear transform, a nonlinear activation function, a convolution, etc. is the input vector, is the output vector from the first module, etc.
BatchNorm is a module that can be inserted at any point in the feedforward network. For example, suppose it is inserted just after , then the network would operate accordingly:
The BatchNorm module does not operate over individual inputs. Instead, it must operate over one batch of inputs at a time.
Concretely, suppose we have a batch of inputs , fed all at once into the network. We would obtain in the middle of the network some vectors:
The BatchNorm module computes the coordinate-wise mean and variance of these vectors:
where indexes the coordinates of the vectors, and indexes the elements of the batch. In other words, we are considering the -th coordinate of each vector in the batch, and computing the mean and variance of these numbers.
It then normalizes each coordinate to have zero mean and unit variance:
The is a small positive constant such as added to the variance for numerical stability, to avoid division by zero.
Finally, it applies a linear transformation:
Here, and are parameters inside the BatchNorm module. They are learnable parameters, typically trained by gradient descent.
The following is a Python implementation of BatchNorm:
import numpy as np
def batchnorm(x, gamma, beta, epsilon=1e-9):
# Mean and variance of each feature
mu = np.mean(x, axis=0) # shape (N,)
var = np.var(x, axis=0) # shape (N,)
# Normalize the activations
x_hat = (x - mu) / np.sqrt(var + epsilon) # shape (B, N)
# Apply the linear transform
y = gamma * x_hat + beta # shape (B, N)
return y
Interpretation
and allow the network to learn to undo the normalization, if this is beneficial. BatchNorm can be interpreted as removing the purely linear transformations, so that its layers focus solely on modelling the nonlinear aspects of data, which may be beneficial, as a neural network can always be augmented with a linear transformation layer on top.
It is claimed in the original publication that BatchNorm works by reducing internal covariance shift, though the claim has both supporters and detractors.
Special cases
The original paper recommended to only use BatchNorms after a linear transform, not after a nonlinear activation. That is, , not . Also, the bias does not matter, since it would be canceled by the subsequent mean subtraction, so it is of the form . That is, if a BatchNorm is preceded by a linear transform, then that linear transform's bias term is set to zero.
For convolutional neural networks (CNNs), BatchNorm must preserve the translation-invariance of these models, meaning that it must treat all outputs of the same kernel as if they are different data points within a batch. This is sometimes called Spatial BatchNorm, or BatchNorm2D, or per-channel BatchNorm.
Concretely, suppose we have a 2-dimensional convolutional layer defined by:
where:
is the activation of the neuron at position in the -th channel of the -th layer.
is a kernel tensor. Each channel corresponds to a kernel , with indices .
is the bias term for the -th channel of the -th layer.
In order to preserve the translational invariance, BatchNorm treats all outputs from the same kernel in the same batch as more data in a batch. That is, it is applied once per kernel (equivalently, once per channel ), not per activation :
where is the batch size, is the height of the feature map, and is the width of the feature map.
That is, even though there are only data points in a batch, all outputs from the kernel in this batch are treated equally.
Subsequently, normalization and the linear transform is also done per kernel:
Similar considerations apply for BatchNorm for n-dimensional convolutions.
The following is a Python implementation of BatchNorm for 2D convolutions:
import numpy as np
def batchnorm_cnn(x, gamma, beta, epsilon=1e-9):
# Calculate the mean and variance for each channel.
mean = np.mean(x, axis=(0, 1, 2), keepdims=True)
var = np.var(x, axis=(0, 1, 2), keepdims=True)
# Normalize the input tensor.
x_hat = (x - mean) / np.sqrt(var + epsilon)
# Scale and shift the normalized tensor.
y = gamma * x_hat + beta
return y
Improvements
BatchNorm has been very popular and there were many attempted improvements. Some examples include:
ghost batching: randomly partition a batch into sub-batches and perform BatchNorm separately on each;
weight decay on and ;
and combining BatchNorm with GroupNorm.
A particular problem with BatchNorm is that during training, the mean and variance are calculated on the fly for each batch (usually as an exponential moving average), but during inference, the mean and variance were frozen from those calculated during training. This train-test disparity degrades performance. The disparity can be decreased by simulating the moving average during inference:
where is a hyperparameter to be optimized on a validation set.
Other works attempt to eliminate BatchNorm, such as the Normalizer-Free ResNet.
Layer normalization
Layer normalization (LayerNorm) is a popular alternative to BatchNorm. Unlike BatchNorm, which normalizes activations across the batch dimension for a given feature, LayerNorm normalizes across all the features within a single data sample. Compared to BatchNorm, LayerNorm's performance is not affected by batch size. It is a key component of transformer models.
For a given data input and layer, LayerNorm computes the mean and variance over all the neurons in the layer. Similar to BatchNorm, learnable parameters (scale) and (shift) are applied. It is defined by:
where:
and the index ranges over the neurons in that layer.
Examples
For example, in CNN, a LayerNorm applies to all activations in a layer. In the previous notation, we have:
Notice that the batch index is removed, while the channel index is added.
In recurrent neural networks and transformers, LayerNorm is applied individually to each timestep. For example, if the hidden vector in an RNN at timestep is , where is the dimension of the hidden vector, then LayerNorm will be applied with:
where:
Root mean square layer normalization
Root mean square layer normalization (RMSNorm) changes LayerNorm by:
Essentially, it is LayerNorm where we enforce .
Adaptive
Adaptive layer norm (adaLN) computes the in a LayerNorm not from the layer activation itself, but from other data. It was first proposed for CNNs, and has been used effectively in diffusion transformers (DiTs). For example, in a DiT, the conditioning information (such as a text encoding vector) is processed by a multilayer perceptron into , which is then applied in the LayerNorm module of a transformer.
Weight normalization
Weight normalization (WeightNorm) is a technique inspired by BatchNorm that normalizes weight matrices in a neural network, rather than its activations.
One example is spectral normalization, which divides weight matrices by their spectral norm. The spectral normalization is used in generative adversarial networks (GANs) such as the Wasserstein GAN. The spectral radius can be efficiently computed by the following algorithm:
By reassigning after each update of the discriminator, we can upper-bound , and thus upper-bound .
The algorithm can be further accelerated by memoization: at step , store . Then, at step , use as the initial guess for the algorithm. Since is very close to , so is to , thus allowing rapid convergence.
CNN-specific normalization
There are some activation normalization techniques that are only used for CNNs.
Response normalization
Local response normalization was used in AlexNet. It was applied in a convolutional layer, just after a nonlinear activation function. It was defined by:
where is the activation of the neuron at location and channel . I.e., each pixel in a channel is suppressed by the activations of the same pixel in its adjacent channels.
are hyperparameters picked by using a validation set.
It was a variant of the earlier local contrast normalization.
where is the average activation in a small window centered on location and channel . The hyperparameters , and the size of the small window, are picked by using a validation set.
Similar methods were called divisive normalization, as they divide activations by a number depending on the activations. They were originally inspired by biology, where it was used to explain nonlinear responses of cortical neurons and nonlinear masking in visual perception.
Both kinds of local normalization were obviated by batch normalization, which is a more global form of normalization.
Response normalization reappeared in ConvNeXT-2 as global response normalization.
Group normalization
Group normalization (GroupNorm) is a technique also solely used for CNNs. It can be understood as the LayerNorm for CNN applied once per channel group.
Suppose at a layer , there are channels , then it is partitioned into groups . Then, LayerNorm is applied to each group.
Instance normalization
Instance normalization (InstanceNorm), or contrast normalization, is a technique first developed for neural style transfer, and is also only used for CNNs. It can be understood as the LayerNorm for CNN applied once per channel, or equivalently, as group normalization where each group consists of a single channel:
Adaptive instance normalization
Adaptive instance normalization (AdaIN) is a variant of instance normalization, designed specifically for neural style transfer with CNNs, rather than just CNNs in general.
In the AdaIN method of style transfer, we take a CNN and two input images, one for content and one for style. Each image is processed through the same CNN, and at a certain layer , AdaIn is applied.
Let be the activation in the content image, and be the activation in the style image. Then, AdaIn first computes the mean and variance of the activations of the content image , then uses those as the for InstanceNorm on . Note that itself remains unchanged. Explicitly, we have:
Transformers
Some normalization methods were designed for use in transformers.
The original 2017 transformer used the "post-LN" configuration for its LayerNorms. It was difficult to train, and required careful hyperparameter tuning and a "warm-up" in learning rate, where it starts small and gradually increases. The pre-LN convention, proposed several times in 2018, was found to be easier to train, requiring no warm-up, leading to faster convergence.
FixNorm and ScaleNorm both normalize activation vectors in a transformer. The FixNorm method divides the output vectors from a transformer by their L2 norms, then multiplies by a learned parameter . The ScaleNorm replaces all LayerNorms inside a transformer by division with L2 norm, then multiplying by a learned parameter (shared by all ScaleNorm modules of a transformer). Query-Key normalization (QKNorm) normalizes query and key vectors to have unit L2 norm.
In nGPT, many vectors are normalized to have unit L2 norm: hidden state vectors, input and output embedding vectors, weight matrix columns, and query and key vectors.
Miscellaneous
Gradient normalization (GradNorm) normalizes gradient vectors during backpropagation.
See also
Data preprocessing
Feature scaling
References
Further reading
Articles with example Python (programming language) code
Deep learning
Statistical data transformation
Machine learning
Neural networks | Normalization (machine learning) | [
"Engineering"
] | 2,804 | [
"Artificial intelligence engineering",
"Neural networks",
"Machine learning"
] |
77,557,454 | https://en.wikipedia.org/wiki/Schenck%20ene%20reaction | The Schenck ene reaction or the Schenk reaction is the reaction of singlet oxygen with alkenes to yield hydroperoxides. The hydroperoxides can be reduced to allylic alcohols or eliminate to form unsaturated carbonyl compounds. It is a type II photooxygenation reaction, and is discovered in 1944 by Günther Otto Schenck. Its results are similar to ene reactions, hence its name.
Reaction conditions
The singlet oxygen reagent can be produced via photochemical activation of triplet oxygen (regular oxygen) in the presence of photosensitizers like rose bengal. Chemical processes like the reaction between hydrogen peroxide and sodium hypochlorite are also viable.
Mechanism and selectivity
Historically, four mechanisms have been proposed:
Experimental and computational studies show that the reaction actually proceeds via a two step no intermediate process. One can loosely interpret it as a mix of the perepoxide mechanism and the concerted mechanism. There is no perepoxide intermediate as in the classical sense of reaction intermediates, for there exists no energy barrier between it and the hydroperoxide product.
Such a mechanism can account for the selectivity of the Schenck ene reaction. The singlet oxygen is more likely to abstract hydrogen from the side with more C-H bonds due to favorable interactions in the transition state:
Very bulky groups, like the tertiary butyl group, will hinder hydrogen abstraction on that side.
Applications
The Schenck ene reaction is utilized in the biological and biomimetic synthesis of rhodonoids, yield
Many hydroperoxides derived from fatty acids, steroids, and terpenes are also formed via the Schenck ene reaction. For instance, the generation of cis-3-hexenal from linolenic acid:
It must be noted, however, that this enzyme catalyzed path follows a different mechanism from the usual Schenck ene reaction. Radicals are involved, and triplet oxygen is used instead of singlet oxygen.
See also
Ene reaction
Photooxygenation
Singlet oxygen
Hydroperoxide
References
Organic reactions
Reaction mechanisms | Schenck ene reaction | [
"Chemistry"
] | 439 | [
"Reaction mechanisms",
"Chemical kinetics",
"Physical organic chemistry",
"Organic reactions"
] |
77,557,563 | https://en.wikipedia.org/wiki/Perianal%20injectable%20bulking%20agent | These procedures aim to inject bio-compatible material (perianal injectable bulking agents, also termed sphincter bulking agents or biomaterial injectables) into the walls of the anal canal, in order to bulk out these tissues. This may bring the walls of the anal canal into tighter contact, raising the resting pressure, creating more of a barrier to the loss of stool, and thereby reducing fecal incontinence. This procedure has many advantages over more invasive surgery, since there are rarely any serious complications.
History
Originally, injectable bulking agents were used to treat stress urinary incontinence in females. The procedure aimed to bulk out the tissues of the neck of the bladder, and it was successful. The technique was first used for FI in 1993 by an Egyptian surgeon. He used polytetrafluroethylene (PTFE/polytef/Teflon) paste injected into the submucosal layer of anal canal. Later publications described autologous transplantation of fat from the abdominal wall or the buttock. After about the year 2000, many different materials started to be used as well as variations of the technique. Some of these materials were concurrently being used to treat urinary incontinence. The latest development of this technique is the implantable bulking agents "Gatekeeper" and "Sphinkeeper". These are not injectable materials but rather implants which expand after placement. As such, they are termed "self-expandable prostheses", and the term "non-self-expandable prostheses" is used to refer to older injectable materials.
Procedure
The exact methods of this procedure are not standardized and vary considerably, for example the exact number and locations of the injections and the volume of the injected material.
Before the operation, antibiotic prophylaxis may be given. The rectum is prepared with a phosphate enema at least 2 hours before the procedure. The procedure can be carried out under local anesthetic on an out patient basis, or with caudal epidural anesthesia, or with intravenous sedation, or under general anesthesia. Ultrasound guidance may be used during the injections, which is sometimes reported as being more effective than the surgeon simply palpating (feeling) and looking where to inject.
The site of the bulking material can be inter-sphincteric (in the space between the IAS and the EAS), submucosal injections (under the mucosal layer, usually just above the dentate line), or within the IAS itself. Injection of the material can be by the different routes: transanal route, trans-sphincteric, intersphincteric, perianal route (going through the muscle complex) or transcutaneous route. As such, there are several different variations of injection location and route:
Trans-sphincteric route into the IAS,
Inter-sphincteric route into the IAS,
Inter-sphincteric route into the submucosa,
Trans-anal injection into the submucosa (similar to injection sclerotherapy for haemorrhoids),
Trans-sphincteric route into the inter-sphincteric space,
Inter-sphincteric route into the inter-sphincteric space,
Trans-sphincteric route injecting submucosally.
The perianal injection route (intersphincteric or transsphincteric) gives better results than the transanal route according to one review. Submucosal implant location may have a higher risk of erosion and sepsis.
Injectable materials
Many different materials have been used as perianal injectable bulking agents. The ideal injectable or implantable material would be biocompatible, non-migratory, non-allergenic, non-carcinogenic and non-immunogenic (and therefore induce a minimal inflammatory and fibrotic reaction). The material should also be easy to inject. The particles should be greater than 80 μm in diameter in order to prevent migration away from the injection site. On the other hand, materials with particles small enough to be used in small caliber needles may be desirable, in order to leave a smaller needle track, which may reduce the chance of leakage of the material via the needle track. Alternatively, some materials are shape-retaining porous hydrogels with no particles. The ideal material should produce an improvement in continence not only in the short term, but in the long term, and repeated procedures should not be necessary. Technically, most materials are particles suspended in a carrier (excipient) solution, which is usually a biodegradable gel. It is not known which of the available materials is the best.
Autologous fat (fat tissue transferred from elsewhere in the body).
Teflon.
Bovine glutaraldehyde cross-linked collagen (collagen from cows).
Carbon-coated zirconium/graphite beads ("Durasphere").
Polydimethylsiloxane elastomer (silicone) biomaterial implants ("PTQ implant").
Dextranomer in non-animal stabilised hyaluronic acid ("Solesta", "NASHA Dx").
Hydrogel cross-linked with polyacrylamide ("Bulkamid").
Porcine dermal collagen (collagen from pig skin, "Permacol").
Synthetic calcium hydroxylapatite ceramic microspheres.
Polyacrylonitrile in cylinder form.
aluminum potassium sulfate and tannic acid (ALTA).
Teflon (polytef)
This was the original material used as a bulking agent, first used to treat urinary incontinence in 1964, and then about 20 years later it was the first material used as a bulking agent to treat FI. Polytef paste is polytetrafluoroethylene, glycerin and polysorbide. The particles are mostly very small in size (4–40-μm). Research in animals has shown that these particles migrate and may be found in lymph nodes, lungs, kidneys, spleen and brain. If the material mostly migrates away, any benefit will be temporary, and there are safety concerns that it could lead to the formation of foreign body granulomas and the development of sarcoma.
Autologous fat transplant
This variation of the procedure uses the patient's own fat cells, and therefore is non-allergenic and non-immunogenic. The fat cells are taken from the abdominal wall by suction. Then they are purified and put into a saline solution before injection. When used in other fields such as urology or facial surgery, autologous fat transplants have very rarely been reported to cause fat embolism and stroke. This material is also subject to rapid digestion and migration.
PTQ implant
This is a silicone biomaterial, marketed as "PTQ" or "Bioplastique". It is polydimethylsiloxane elastomer particles suspended in a biocompatible carrier hydrogel of poly-N-vinyl-pyrrolidone (povidone). Significantly more publications exist which investigate this material compared to the other materials, and it has been the most widely used bulking material used for FI. Publications used inter-sphincteric or within IAS injection sites via the trans-sphincteric route. The particles are in the range 100–450 μm with smaller particles in the gel. Therefore there is a possibility of migration and granuloma formation. There are also concerns about a link between autoimmune diseases and silicone. The bulking agent is very viscous which makes it difficult to inject. After injection there is irregular collagen deposition around and inside the implant.
Durasphere
After PTQ, this material has most scientific publications. Publications described using it via the transmucosal or trans-sphincteric routes, with the end location of the material being the submucosa. It is composed of carbon-coated zirconium beads (pyrolytic carbon-coated beads) in a water-based carrier gel containing β-glucan. Pyrolytic carbon is not biologically reactive and does not undergo degradation. It is used in various medical devices including heart valves. The particle size of Durasphere is in the range 212-500 μm, which is approximately 3 times the migration threshold of 80 μm. However, one report of the material as used in urology showed significant migration to local and distant lymph nodes.
Dextranomer in sodium hyaluronate
This is a newer material which became more popular after 2011. It is marketed as NASHA Dx, Zuidex, or Solesta. As of 2022, NASHA Dx is the only material approved in the US by the U.S. Food and Drug Administration (FDA). This material is composed of crosslinked dextranomer (dextran) microspheres and non-animal stabilized sodium hyaluronate (NASHA) in phosphate-buffered 0.9% sodium chloride solution. The particles are 120 μm in diameter. The material is non-allergenic, non-immunogenic and non-migratory. After injection, the hyaluronic acid is degraded, and soft tissue fibrosis forms with ingrowth of fibroblasts, inflammatory cells, blood vessels and collagen. This means that even though the particles undergo degradation, the bulking effects may persist. There are several publications which report the use of this material. They used submucosal injection site via the transmucosal route. Uncertainty about indications, cost, and durability of the material in the long term stopped widespread adoption of this material.
Calcium hydroxylapatite
Marketed as "Coaptite", this is spherical particles of calcium hydroxylapatite ceramic suspended in a sodium carboxylmethylcellulose, glycerine and water carrier gel. This is a synthetic version of a compound that is a normal component of bones and teeth. It is non-antigenic and noninflammatory. The particle size is in the range 75–125 μm and therefore should avoid migration away from the implant site. Once in place, the particles are enmeshed in a non-encapsulated stable soft collagen matrix. This matrix maintains volume even after the solid particles have been degraded and resorbed. The material is radio-opaque (and therefore will be visible on x-rays). It has been used in dental and orthopedic reconstructive surgery, and for replacement heart valves. In the field of plastic surgery, it is termed Radiance FNTM. As of 2022 only one publication exists. The material was used in submucosal injection site via transsphincteric route.
GAX (glutaraldehyde cross-linked) collagen
GAX (glutaraldehyde cross-linked) collagen is purified collagen from cow skin, marketed as Contigen. Enzymes are used to remove telopeptides, which reduces the antigenicity (the degree to which the body's immune cells will be able to recognize the material as a foreign body). About 5% of patients will have an immune reaction to this material, therefore allergy testing is carried out before the final procedure. There is also a concern about disease transmission. This material contains 95% collagen Type I and 1-5% of collagen Type III. Chemical cross-linking with glutaraldehyde is intended to stop the degradation of the material by collagenases. The carrier solution is physiological saline with phosphate. The material does not seem to be associated with formation of granulomas or migration, however it is subject to degradation over time. In publications is has been used with submucosal injection site via transmucosal route. This material has not achieved widespread use.
Porcine dermal collagen
Cross-linked porcine dermal collagen matrix (collagen from pig skin) has been used, marketed as Permacol. It consists of large particles of cross-linked porcine dermal collagen. It has been used for urinary incontinence and for facial contour augmentation, as well as for FI. It is biocompatible, non-allergenic and has improved durability due to revascularization and cell ingrowth following injection. In several publications where the material was used for FI, submucosal or intersphincteric injection site was used, via the transmucosal or intersphincteric routes.
Hydrogel cross-linked with polyacrylamide
Marketed as Bulkamid, this material is a synthetic non-particulate hydrogel composed of water and cross-linked polyacrylamide (2.5%). The size of the molecules is large which makes it resistant to migration. Since it is a non particulate homogeneous hydrogel, it is thought to retain elasticity and does not lead to hard tissue fibrosis or cause other significant reaction in the surrounding tissues. It is non-resorbable and non allergenic. In plastic surgery it is marketed as Aquamid. In one publication where it was used for FI, intersphincteric injection site was used via the intersphincteric route. This material has not achieved widespread use.
Aluminum potassium sulfate and tannic acid (ALTA)
ALTA injection is somewhat different to the other materials because it is a sclerosant (i.e. it is a type causes sclerosis, or hardening of tissue). Therefore, it may be technically classified as a type of sclerotherapy. This injectable material has been used for treatment of grade III to IV prolapsed internal hemorrhoids, where it gives effects similar to hemorrhoidectomy. It has also been used for treatment of rectal prolapse and rectocele. The material causes a local inflammatory reaction, followed by sclerosis and retraction of tissues. This results in a chronic granulomatous inflammatory process and persistent fibrosis. When used to treat rectal prolapse or mucosal prolapse, it is injected into a wider area (not just into the hemorrhoid cushions, but also into parts of the rectal mucosa), leading to thickening and toughening of the anal canal and rectal wall. This has been shown to increase the maximal resting pressure of the anal canal. Therefore, the result is thought to be similar to other injectable bulking agents, although it is claimed that there is no risk of dissipation and no need for repeated procedures. ALTA has the advantage that it may be used to treat related anorectal conditions which would be contraindications for other injectable bulking agents.
Ethylene vinyl alcohol co-polymer in dimethyl sulfoxide
8% ethylene vinyl alcohol co-polymer in dimethyl sulfoxide solution has been used. For FI it is marketed as Onyx34, and for gastroesophageal reflux disease it is marketed as Enteryx. After injection, it forms a spongy solid mass via solidification of the hydrophobic copolymer. This occurs because the co-polymer is hydrophic, and the solvent is dissolved away upon contact with tissues. In one publication inter-sphincteric injection site was used via the inter-sphincteric route.
Stem cells
Mesenchymal stem cells (MSC) and muscle-derived stem cells (MDSC) have been used in urology to treat urinary incontinence. Fibroblasts in a collagen carrier were injected into the submucosa of the urethra, and myoblasts were injected into the urethral sphincter. The procedure was reported as being successful in most cases. Injection of MSCs may lead to engrafting and forming multinucleated myotubes, which helps to regeneration after injury. In theory, use of stem cells removes the problems of reabsorption and migration of the bulking material. There is similar research which aims to regenerate muscles and repair tissues by cell therapy to treat injuries of the external anal sphincter.
Gatekeeper and Sphinkeeper implants
The "Gatekeeper" and "Sphinkeeper" are related procedures. They are self-expandable prostheses which are implanted into the inter-sphincteric space of the anal canal using an applicator gun. Gatekeeper is a solid polyacrylonitrile (hyexpan) cylinder which expands to approximately 720% original size within 24 hours after the implantation.
Complications
One review of 23 publications involved a total of 889 patients reported an overall rate of complications of 18%.
Reported complications are mostly minor, and include: bleeding, perianal pain / discomfort (which may rarely be persistent), leakage of injected material, infection / abscess (which rarely may require drainage), mucosal erosion, obstructed defecation, hypersensitivity reaction, hematoma, diarrhea, pruritus ani, dermatitis, and bowel urgency (sudden strong urge to defecate).
Effectiveness
A landmark randomized placebo control trial on NASHA Dx was published in 2011 in the Lancet. 136 were given real injections and 70
patients were given shame (fake) injections. 80% of the patients had no improvement 1 month after the procedure, and were given a second injection. After 6 months, 52% of patients who received real injections had improved symptoms. However, the patients who received fake injections reported over 30% improvement in symptoms, suggesting that patient psychology (i.e. the placebo effect) may be in part responsible for any positive results. 6% of patients who received real injections were fully continent after 6 months. After publication of this study, the material was approved by the FDA in the USA in 2012. The material was aggressively marketed, and became popular for a time because of its potential as an in office treatment with low risks compared to other surgical options. However uncertainty about indications, cost, and long term durability stopped widespread adoption.
A Cochrane systematic review of the efficacy of this type of treatment for FI was updated in 2013. The review included 5 randomized trials, which in total was 382 patients. 4 of the trials were assessed as uncertain or high risk of bias. Another commentator drew attention to the fact that all existing research on these procedures was driven by the companies who also marketed the treatments, and therefore the studies are indeed at high risk of bias. Another author in 2008 raised concern that 2 randomized placebo controlled trials had been conducted, but their results remained unpublished for unknown reasons. None of the studies in the Cochrane review reported long term follow up after 3, 6 or 12 months post procedure. Another problem with some of the trials is that they were too small.
The Cochrane review found that most trials reported short term improvement following the procedure, regardless of which material was used. In some studies in the control groups, even placebo (sham) injections and saline injections lead to patients reporting improvement. One trial showed that dextranomer (NASHA Dx) was more effective six months after the procedure compared to placebo for just over half of patients. Another study showed that PTQ has some advantages and was safer than Durasphere in the short term. The authors concluded that due to the small amount of research available and its methodological weaknesses, further conclusions could not be made, especially regarding the long term effectiveness of the procedure.
Another review which aimed to focus on the long term impact of the procedure included 889 patients across 23 studies. It reported a pooled improvement rate in measures of incontinence of 39.5%, on average 2 years after the procedure. In some cases there was no improvement after the procedure, and the injections needed to be repeated in up to 34% of cases. There can also be worsening of symptoms after an initial improvement period.
A randomized trial by Dehli et al. compared perianal injectable bulking agents to sphincter training and biofeedback, and found the former to be superior. Both methods lead to an improvement of FI, but comparisons of St Mark's scores between the groups showed no difference between treatments.
Anal manometry is sometimes used to investigate changes in the anal canal before and after the procedure. Usually mean anal resting pressure and mean anal squeeze pressure are the parameters used. Improvements in these measurements are often, but not always reported up to 3–12 months after the procedure. These improvements are not always maintained after 12 months. The length of the anal canal has also been reported to increase following the procedure. In one report, dextranomer did not increase anal resting or squeeze pressures. In the same study, dextranomer injections were found to be no different to biofeedback.
There is limited research available on this topic, and these publications are mostly of poor quality. Apart from the available research, most of the claims of benefit of these procedures is anecdotal.
One author criticized these procedures, stating that simply narrowing the anal canal was an instinctive and naïve solution which does not consider the complex pathopysiological mechanisms of FI. They suggested that these treatments are in theory suitable only for passive and minor forms of FI. Concerns have been raised about migration of the particles (in the case of Durasphere) away from the site of injection, or the total resorption of the material (in the case of hyaluronic acid and hydroxyl coaptite). Most research suggests that the positive effects of most of the bulking agents seem to reduce after 6 to 12 months. Endoanal ultrasound has sometimes been used to assess the presence of the material at follow up. At 6 months the material has been reported as missing or migrated in 18.4% of cases, at 3 years or more in 20.2% of cases. NASHA Dx and ALTA injection may have longer lasting effects, with most patients still having improvement after 3 years.
References
External links
Colorectal surgery
Incontinence | Perianal injectable bulking agent | [
"Biology"
] | 4,713 | [
"Incontinence",
"Excretion"
] |
77,558,175 | https://en.wikipedia.org/wiki/1-Chlorohexane | 1-Chlorohexane is a chemical compound from the group of aliphatic saturated halogenated hydrocarbons. The chemical formula is .
Synthesis
1-Chlorohexane can be obtained by reacting hexyl alcohol with hydrochloric acid or thionyl chloride.
Physical properties
1-Chlorohexane is a colorless liquid with an aromatic odor that is very sparingly soluble in water.
Chemical properties
1-Fluorohexane can be prepared by reacting 1-chlorohexane with potassium fluoride in ethylene glycol.
2-Phenylhexane can be prepared by reacting the compound with benzene and aluminum trichloride.
See also
1-Fluorohexane
1-Bromohexane
1-Iodohexane
References
Chloroalkanes
Alkylating agents | 1-Chlorohexane | [
"Chemistry"
] | 182 | [
"Alkylating agents",
"Reagents for organic chemistry"
] |
70,315,826 | https://en.wikipedia.org/wiki/Freyssinet%20Test%20Arch | The Freyssinet Test Arch (in French Arche d'essai Freyssinet) is a prestressed concrete arch built in 1909 in Moulins, Allier by Eugène Freyssinet1. Its purpose was to test the resistance of this material to traction exerted on very flat and long-range arches. Freyssinet wanted to validate this prestressed concrete technique which he had perfected before the construction of three road bridges over the Allier river which he was to undertake in the following years: the , the and the Châtel-de-Neuvre bridge. As the first testimony to this innovative technique, the arch has been registered as a Monument historique since October 2021 with Boutiron Bridge, the only existing original bridge of the three.
References
Prestressed concrete construction
Buildings and structures in Moulins, Allier
Monuments historiques of Allier
1909 in technology | Freyssinet Test Arch | [
"Technology"
] | 187 | [
"Structural system",
"Prestressed concrete construction"
] |
70,315,836 | https://en.wikipedia.org/wiki/Rachel%20Wynberg | Rachel P. Wynberg is a South African biodiversity researcher and natural scientist who is a professor at the department of Environmental and Geography Sciences at the University of Cape Town.
Life and work
Education
At the University of Cape Town, Wynberg earned a BSc in zoology, MSc in marine biology and a MPhil in environmental science. She went on to obtain a PhD in environmental science at the University of Strathclyde in Scotland.
Research
She advises governments, civil organisations and international agencies and is actively involved with policy debates and initiatives throughout southern Africa.
Her work concerns the taking and using of biological entities from indigenous people without proper acknowledgement or compensation. Specifically, "Biopiracy is the misappropriation of traditional knowledge and biodiversity through the patent system... It's been prevalent for centuries in Southern Africa".
One instance that she has cited concerned the San people.An African example of biopiracy is the case of the Hoodia succulent plant, which grows in the Kalahari Desert. For generations the San people have used it as an appetite and thirst suppressant. But in 1996 the South African Council for Scientific and Industrial Research (CSIR) isolated the hunger-suppressing chemical component in Hoodia and patented it. The CSIR licensed the UK-based Phytopharm for further development. None of the projected royalties were earmarked for the San. In fact, a Phytopharm spokesperson said that the CSIR had led him to believe that the San people were "extinct". In a victory against biopiracy, the CSIR eventually signed an agreement to recognise and reward the San as holders of traditional knowledge.
Wynberg chaired part of the First International Meeting Against Biopiracy, held at the French National Assembly in Paris and attended by representatives from 15 countries including indigenous groups, attorneys, academic researchers and entrepreneurs. The goal of the meeting was to explore the complexities of biopiracy and the threat it poses to cultural and biological diversity. The meeting was hosted by a group of French non-governmental organisations, under the leadership of the former first lady of France, Danielle Mitterrand.
Distinctions
Wynberg was elected a member of the Academy of Science of South Africa in 2018.
Selected publications
.
References
External links
Publications at ResearchGate
Living people
South African scientists
Members of the Academy of Science of South Africa
Year of birth missing (living people)
South African academics
South African women academics
South African women activists
Biodiversity of South Africa | Rachel Wynberg | [
"Biology"
] | 506 | [
"Biodiversity",
"Biodiversity of South Africa"
] |
70,317,127 | https://en.wikipedia.org/wiki/Philanthropy%20as%20a%20service | Philanthropy as a service (PHaaS) is a type of philanthropy in which charitable giving is managed through technology and donor-advised funds.
Overview
Typically, corporate giving is a centralized function, controlled directly by a CEO or a small foundation team of the organization.
The application of philanthropy as a service helps decentralize corporate giving by engaging employees and stakeholders, and empowering donors of any size. It is a software service that facilitates individuals to partake and structure charitable giving, without relying on other parties in an organization. The service providers offer charitable fundraising tools and administrative services as an employee benefit. They set up personal funds for employees in which the employees can put a percentage of their paycheck. As a result, employees are able to contribute to charities and causes of their choice, with employers providing tax-advantaged matching funds.
See also
as a service
References
As a service
Philanthropy
Software industry | Philanthropy as a service | [
"Technology",
"Engineering",
"Biology"
] | 181 | [
"Behavior",
"Altruism",
"Software engineering",
"Computer industry",
"Philanthropy",
"Software industry"
] |
70,317,714 | https://en.wikipedia.org/wiki/Honorary%20Diploma%20of%20the%20Cabinet%20of%20Ministers%20of%20Ukraine | The Honorary Diploma of the Cabinet of Ministers of Ukraine is a government award for many years of hard work, exemplary performance of official duties, personal contribution to economic, scientific, technical, socio-cultural, military, public and other spheres of activity, service to the Ukrainian people in promoting the rule of law and implementation of measures to ensure the protection of the rights and freedoms of citizens, the development of democracy, and the effective operation of executive bodies and local governments.
Recipients
See also
Honorary Diploma of the Verkhovna Rada of Ukraine
Diploma of the Verkhovna Rada of Ukraine
Awards of Ukraine
Orders, decorations, and medals of Ukraine
References
Ukrainian awards
Badges
Recipients of the Honorary Diploma of the Cabinet of Ministers of Ukraine | Honorary Diploma of the Cabinet of Ministers of Ukraine | [
"Mathematics"
] | 147 | [
"Symbols",
"Badges"
] |
70,318,776 | https://en.wikipedia.org/wiki/Crib%20A%27Glow | Crib A'Glow is a portable solar-powered phototherapy unit that uses blue LED lights to treat infants with jaundice. The device was invented by Virtue Oboro, a visual designer and mother whose newborn son had developed jaundice. Crib A'Glow has won multiple prizes for innovation.
Background
In 2015, Oboro's son developed symptoms of jaundice soon after birth. The nearby hospital had five phototherapy units; however, two were already in use and the other three were inoperable. Once he was in a phototherapy unit, a power outage led to him developing severe jaundice for which he received an emergency blood transfusion. Jaundice affects more than 60% of newborns throughout the world, with the most serious cases requiring phototherapy. In Nigeria, it is estimated that fewer than 5% of medical facilities have sufficient phototherapy devices to treat the condition. Approximately 100,000 infants die annually from jaundice, with many more experiencing permanent injuries.
After Oboro's son recovered, she and her husband began their Tiny Hearts Technology company to work on the development of a portable crib that could use solar power to provide phototherapy to jaundiced infants.
Description
Oboro was assisted by her husband's experience with solar energy and a pediatrician who helped ensure the device met phototherapy guidelines and was safe.
Manufactured in Nigeria and using local materials, Crib A'Glow is affordable, retailing at $360 compared to $2,000 for other phototherapy units used in Nigeria. Phototherapy devices used in developed countries have common side effects such as skin burns, dehydration, and rashes. Crib A'Glow avoids these side effects through the use of LED lights.
The portable unit is particularly useful in remote areas where access to electricity can be limited or inconsistent.
Crib A'Glow is in use at hundreds of hospitals in Nigeria and Ghana and has treated about 300,000 babies as of December 2021.
Awards
Johnson & Johnson awarded Crib A'Glow $50,000 as one of six winners of its Champions of Science Africa Innovation Challenge 2.0. Tiny Hearts Technology, Oboro's company, received the third-place prize from the Africa Business Center of the United States Chamber of Commerce for its inaugural Digital Innovation Awards in 2020. The device was selected by the Royal Academy of Engineering for the Africa Prize 2022 shortlist.
References
Healthcare in Nigeria
Medical technology | Crib A'Glow | [
"Biology"
] | 499 | [
"Medical technology"
] |
70,319,019 | https://en.wikipedia.org/wiki/Patrizia%20Gianni | Patrizia M. Gianni (born 1952) is an Italian mathematician specializing in computer algebra. She is known for her early research on Gröbner bases including her discovery of the FGLM algorithm for changing monomial orderings in Gröbner bases, and for her development of the components of the Axiom computer algebra system concerning polynomials and rational functions.
Gianni is a professor of algebra in the mathematics department of the University of Pisa. She earned a laurea from the University of Pisa, and has worked for IBM Research as well as for the University of Pisa.
References
External links
Home page
Living people
Italian mathematicians
Italian women mathematicians
University of Pisa alumni
Academic staff of the University of Pisa
Algebraists
1952 births | Patrizia Gianni | [
"Mathematics"
] | 146 | [
"Algebra",
"Algebraists"
] |
70,319,122 | https://en.wikipedia.org/wiki/Y%20Tauri | Y Tauri is a carbon star located in the constellation Taurus. Parallax measurements by Gaia put it at a distance of approximately 2,170 light-years (670 parsecs).
Y Tauri is a semiregular variable star. Its class is SRb, and its primary pulsation cycle lasts 241.5 days. No long secondary period has been identified. It has a radius of , an effective surface temperature of , and a bolometric luminosity of . Its mass is calculated to be .
Y Tauri is losing mass at /yr, and is surrounded by dust at a temperature of .
References
Semiregular variable stars
Scutum (constellation)
Tauri, Y
Carbon stars
Durchmusterung objects
038307
027181
1977
TIC objects | Y Tauri | [
"Astronomy"
] | 170 | [
"Scutum (constellation)",
"Constellations"
] |
70,321,372 | https://en.wikipedia.org/wiki/Stephenson%202%20DFK%2049 | Stephenson 2 DFK 49 or St2-11 is a putative post red supergiant star in the constellation Scutum, in the massive open cluster Stephenson 2. It is possibly one of the largest known stars with a radius estimated to be between to ,. If it was placed at the center of the Solar System, its photosphere would potentially approach or engulf Jupiter's orbit. It loses mass at a very high rate, resulting in large amounts of infrared excess.
Observation history
The open cluster Stephenson 2 was discovered by American astronomer Charles Bruce Stephenson in 1990 in the data obtained by a deep infrared survey. The cluster is also known as RSGC2, one of several massive open clusters in Scutum, each containing multiple red supergiants. The 49th brightest star in the K band was given an identifier number of 49.
The authors noted that the star likely had significant circumstellar and interstellar extinction, higher than even the other cluster members, and noted that its spectral type places it near yellow hypergiants on the Hertzsprung–Russell diagram (HR Diagram), though not as hot.
In a later study from 2010, the same star was given the identifier number 11, and was grouped with a proposed cluster assumed to be associated with Stephenson 2, Stephenson 2-SW. The star showed maser emissions at some spectral lines. A later study corroborates this. The study mentions a weak CO emission with radial velocities similar to Stephenson 2 DFK 49, but it is said to be unrelated due to being too intense for a red supergiant at Stephenson 2 DFK 49’s distance.
Another study observed and studied 57 red supergiant stars across the galaxy and gave estimates of the stars' properties based on their Spectral Energy Distributions, like luminosity and temperature.
In 2016, it was compared to the yellow hypergiant star IRAS 18357-0604, which can be found in the same general region as Stephenson 2.
A recent study on red supergiant mass loss rates and histories notes it as the most interesting object in the cluster, because its spectral energy distribution, which has a significant infrared excess, is similar to that of the famous and extreme red hypergiant VY Canis Majoris. However, Stephenson 2 DFK 49 is hotter. The study also estimates the possible mass loss rates of the star, as well as its other properties.
Properties
Stephenson 2 DFK 49 was known to be an interesting object since its home cluster was first studied in depth. An interesting note about Stephenson 2 DFK 49 is that it appears to be at the center of a bow-shock structure in infrared images. Because of its properties and likely position on the H-R diagram, the authors of Davies 2007 stated that both it and Stephenson 2 DFK 1 warranted further studies, especially in terms of stellar evolution. Its properties, an earlier than usual spectral type compared to other stars in Stephenson 2, its luminosity and position on the HR Diagram indicate that it is similar to the extreme yellow hypergiant star IRC+10420 and Variable A in the Triangulum Galaxy (M33). Stephenson 2 DFK 49 is comparable to another extreme star in the vicinity of Stephenson 2, IRAS 18357-0604. Both are possible post-red supergiant stars, and both of them are comparable to the yellow hypergiant IRC+10420.
Luminosity
In 2007, a study of the red supergiants in Stephenson 2 estimated its properties and determined a bolometric luminosity of . A 2012 study estimated and published the properties of numerous red supergiants and other supergiant stars. The study estimated Stephenson 2-11's luminosity at a much lower , using spectral energy distribution (SED).
Using the SED, Humphreys (2020) estimates a luminosity of . However, it is noted that the estimated luminosity may be an underestimate, because it does not include excess radiation from warm dust.
Temperature and Spectrum
Davies (2007) estimated its temperature of , but with an uncertainty in the measurement of ± 112 K. 5 years later, Fok (2012) estimated a slightly cooler temperature at . A more recent study estimated the star's temperature at a hotter , based on its spectral type of K4.
Size
Davies (2007) estimates a temperature of , with a luminosity of . Applying the Stefan-Boltzmann law, Stephenson 2 DFK 49’s radius would be , making it one of the largest stars known. A 2012 study published the estimated properties of numerous red supergiants and other supergiant stars using Spectral Energy Distributions, including Stephenson 2 DFK 49. The study estimates its temperature at a slightly cooler but its luminosity at a much lower . This would imply a radius of only , smaller than the radius implied by Davies (2007). Humphreys (2020) estimates Stephenson 2 DFK 49's temperature at , but a higher luminosity of . Applying the Stefan-Boltzmann law, its radius would be , larger than the other two estimates.
Mass loss and maser emissions
While Davies (2007) does not estimate a mass loss rate for Stephenson 2 DFK 49, the study mentions that it would be interesting to estimate its mass loss rate. In 2012, it was noted for having maser emissions at certain spectral lines. A 2020 study later determines a mass loss rate of 1.3-7*10−4 per year based on several computer models, but it is noted that these rates are not high for other hypergiant stars such as VY Canis Majoris, NML Cygni and IRC+10420. As a possible post-red supergiant star, Stephenson 2 DFK 49 likely experiences both constant and variable mass-loss rates.
Evolution and future
A star with the properties of Stephenson 2 DFK 49 would imply an initial mass of more than .
Because Stephenson 2 DFK 49 has lost so much mass and continues to do so, and its likely status as a post-red supergiant star, it is likely on the verge of shedding all of its outer layers and becoming a luminous blue variable or a Wolf-Rayet star.
References
Scutum (constellation)
J18390558-0604265
K-type supergiants
IRAS catalogue objects
TIC objects | Stephenson 2 DFK 49 | [
"Astronomy"
] | 1,314 | [
"Scutum (constellation)",
"Constellations"
] |
70,321,679 | https://en.wikipedia.org/wiki/Wetting%20solution | Wetting solutions are liquids containing active chemical compounds that minimise the distance between two immiscible phases by lowering the surface tension to induce optimal spreading. The two phases, known as an interface, can be classified into five categories, namely, solid-solid, solid-liquid, solid-gas, liquid-liquid and liquid-gas.
Although wetting solutions have a long history of acting as detergents for four thousand plus years, the fundamental chemical mechanism was not fully discovered until 1913 by the pioneer McBain. Since then, diverse studies have been conducted to reveal the underlying mechanism of micelle formation and working principle of wetting solutions, broadening the area of applications.
The addition of wetting solution to an aqueous droplet leads to the formation of a thin film due to its intrinsic spreading property. This property favours the formation of micelles which are specific chemical structures consisting of a cluster of surfactant molecules that has a hydrophobic core and a hydrophilic surface that can lower the surface tension between two different phases.
In addition, wetting solutions can be further divided into four classes; non-ionic, anionic, cationic and zwitterionic.
The spreading property may be examined by adding a drop of the liquid onto an oily surface. If the liquid is not a wetting solution, the droplet will remain intact. If the liquid is a wetting solution, the droplet will spread uniformly on the oily surface because the formation of the micelles lowers the surface tension of the liquid.
Wetting solutions can be applied in pharmaceuticals, cosmetics and agriculture. Albeit a number of practical uses of wetting solutions, the presence of wetting solution can be a hindrance to water purification in industrial membrane distillation.
History
Wetting agent was used as soap for cleansing purposes for thousands of years. The oldest evidence of wetting solution went back to 2800 BC in ancient Babylon. The earliest credible reference of soap is in the writings of Galen, the Greek physician, around 200 AD. Over the following centuries, wetting solutions mainly functioned as detergents due to their wetting properties. Despite the extensive use of wetting solutions, the underlying chemical mechanism remained unknown until the emergence of McBain's proposed theory in 1913. Founded on his research on how the electrical conductivity of a solution of surfactant molecules changed with concentration, he raised the possibility of surfactant molecules in the form of self-assembled aggregates. Not until Debye published his original hypothesis in 1949 did he described the reason of micelle formation and the existence of finite-shaped micelles. McBain's discovery sparked numerous studies by Hobbs, Ooshika, Reich and Halsey from 1950 to 1956. These scholars intended to correct some of the foundational theories of the description of an equilibrium system, as well as emphasising the role of surface energy which was overlooked in Debye's prototype. In 1976, the fundamental theory for understanding the mechanism of micelle formation was developed by Tanford's free energy model. Apart from integrating all relevant physicochemical elements and explaining the growth of micells, he provided a comprehensive reasoning of why micelles are finite in terms of opposing interactional forces.
Mechanism
The chemical structure of wetting solution molecules consist of a hydrophilic head and a long hydrophobic tail. Its distinct amphiphilicity allows it to bury its hydrophilic head in an aqueous bulk phase and hydrophobic part in the organic bulk phase respectively. Wetting solution molecules break the intermolecular forces between each molecule in the organic phase and each water molecule in the aqueous phase by displacement. Due to the lowered attractive forces, the surface tension is reduced.
Upon adding more wetting solution, the elevated concentration of wetting solution molecules leads to a further decrease in surface tension and makes the molecules at the surfaces become more crowded. The molecules will be forced to remain in the aqueous phase when there are no more vacancies for them to stay on the surface. At this point, the surface tension is maximally lowered and is termed as the critical micelle concentration (CMC). The lower the CMC, the more efficient the wetting solution is in reducing surface tension. Any additional wetting solution molecules will undergo self-aggregation into several special structures called micelles. Micelles are spheres with a hydrophobic core formed by the non-polar tail of wetting solution molecules and are surrounded by a hydrophilic layer arising from the molecules’ polar heads. Extra wetting solution molecules will be forced to form micelles instead of adhering to the surface, hence the surface tension remains constant. Due to the minimised surface tension, the droplet can now spread thoroughly and form a thin film on the surface.
Classification
Generally, the wetting solution molecules consist of a hydrophilic head and a long hydrophobic tail. The hydrophobic region usually contains saturated or unsaturated hydrocarbon chains, heterocyclic rings or aromatic rings. Despite the similar amphiphilic composition, the molecules can be divided into four classes with respect to the nature of the hydrophilic group, namely, non-ionic, anionic, cationic and zwitterionic.
The following table shows the composition, special features of the corresponding classes and common examples of various forms of the respective wetting solutions.
Applications
Generally, wetting solution is applied in pharmaceuticals, cosmetics and agriculture. McBain’s research on maximising the application of wetting solutions have an important role in enabling a range of options to both manufacturers and consumers and improving product performance in the respective areas of application, such as modifying the stability of pharmaceuticals, delivery of drugs, effectiveness of cleansing products and water retention in soils.
Pharmaceuticals
Specific properties of different wetting solutions are able to alternate drug delivery which is beneficial in improving drug safety and patients' experiences . For example, solulan C-24, a non-ionic wetting solution, forms large bilayers of wetting solution molecules known as discosomes that have a lower risk of causing systemic adverse effects. Non-ionic wetting solutions are found to have a wider usage and are more efficient in reducing surface tension compared to ionic wetting solutions which have higher toxicity and CMC value in general. To ensure the safety, efficacy and quality of the preparations, toxicity and interaction profiles of the choice of wetting solutions are carefully investigated.
Dosage form: Suspensions
Suspension preparation is a liquid dosage form that contains insoluble solid drug particles. The suspension preparation is ideal if solid particles that have become compacted together during storage can re-disperse throughout the liquid vehicle readily with gentle shaking for a period of time that is sufficient for measuring the required dosage.
Solid particles have a natural tendency to aggregate and eventually cause caking due to the presence of air film coating. A solution to this is using a wetting solution as the liquid vehicle for suspension preparation. Wetting solution increases the dispersal ability of the solid particles by replacing the air film to increase steric hindrance and minimise interactions between solid particles and resulting in a decreased rate of aggregation.
Topical ophthalmic solutions
Wetting solutions lowers the surface tension of topical ophthalmic solutions and induces instant spreading when applied onto the cornea by increasing the interaction between the two. The instant spreading increases the amount of drug molecules that are exposed to the cornea for absorption and therefore a quicker onset of action. The increased interaction allow the topical ophthalmic solutions to remain on the corneal surface for a longer period of time to maximise the amount of drug that can diffuse from the applied topical ophthalmic solution layer to the corneal epithelium through tear film, the protective layer of the cornea from the external environment.
Cosmetics: Skin cleansing products
Skin cleansing products including facial cleanser, body wash and shampoo consist of wetting solutions. Wetting solutions allow efficient spreading and wetting of the surface of skin and scalp by reducing the surface tension between the hydrophobic sebum secreted by the sebaceous gland in our skin. An efficient wetting solution penetrates the skin and clears any topical applications, body fluids including sebum secreted via openings of hair follicles, dead skin cells and microbes.
Non-ionic wetting solutions have a low risk of causing skin irritation and are efficient in reducing surface tension between different ingredients, for example, fragrance and essential oils extracted from plants, in skin cleansing products to produce a consistent liquid formula. However, non-ionic wetting solutions are of higher cost than the other types of wetting solutions hence are less favourable for commercial products.
Cationic wetting solutions cause more severe skin irritation problems hence are not used in skin cleansing products. They are used in hair conditioners that are only applied to the second half hair length and washed off after a short period of time.
Anionic and amphoteric wetting solutions are often used as a mixture in body wash and shampoo. The anionic wetting solutions formulated into skin cleansing products have often undergone chemical modification as they often contain sulphur which triggers skin irritation by causing collagen in skin cells to swell and sometimes cell death. Examples of modified anionic wetting solutions include ammonium laureth sulphate and modified sulfosuccinates, both reported to exhibit low skin irritation.
Agriculture
Wetting solutions are widely used in Agriculture to increase crop yield which is affected by the degree of infiltration and penetration of water, nutrients and chemicals such as fertilisers and pesticides. Wetting solutions reduce surface runoff of water and nutrients and enhance water infiltration in water repelling soil by reducing surface tension. Wetting-solution-treated soil has shown to retain high water content and an even distribution of nutrients in the root zone that are in deep soil areas, benefiting crop yield and improving water efficiency. Examples of wetting solutions used in agriculture are modified alkylated polyol, mixture of polyether polyol and glycol ether and mixture of poloxalene, 2-butoxyethanol.
Industrial concerns
Membrane distillation is a water purification process that utilises a hydrophobic membrane with pores to separate water vapour from contaminants, for example, oil and unwanted chemicals. The filtration efficiency and stability of the membrane can be diminished by wetting. Wetting of the hydrophobic membrane is resulted from the presence of wetting solution in sewage due to its increasing large variety of usage in different fields, for example, pharmaceuticals, cosmetics and agriculture. A possible solution is to pretreat the sewage to remove wetting solutions, limiting the amount of wetting solution in contact with the membrane. Other possible solutions to lengthen durability of the membrane include modification of the membrane material repellent to water and oil, air-backwashing and membrane surface geometry modification. These solutions are costly and require further research and development to optimise the durability and efficiency of membrane distillation.
References
Chemical compounds
Chemical substances
Liquids | Wetting solution | [
"Physics",
"Chemistry"
] | 2,260 | [
"Molecules",
"Chemical compounds",
"Phases of matter",
"Materials",
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"Matter",
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70,321,872 | https://en.wikipedia.org/wiki/Capital%20Garage | The Capital Garage was a ten-story parking garage that once stood at 1320 New York Avenue NW in downtown Washington, D.C. It was built for the Shannon & Luchs real estate firm and designed by local architect Arthur B. Heaton, whose landmark buildings in the city include Riggs National Bank, Stockton Hall, and the Churchill Hotel. The building was designed in the Streamline Moderne architectural style with Gothic Revival features. Ornamental details on its façade included bas-reliefs of automobiles and headlights as well as lion-headed grotesques. In addition to providing parking spaces, the Capital Garage also included a gas station, carwash, repair shop, and retail space.
There was a need for parking in downtown Washington, D.C., due to increased car ownership in the 1920s, and once completed, the building was reportedly the largest parking structure of its kind in the country. It proved to be popular with customers and local businesses. During World War II, the US government leased the building for government vehicles and storage space. It later housed a car dealership and was the site of a fundraiser featuring a vehicle once driven by Adolf Hitler. Due to the increase in automobile size in the 1950s and 1960s, the parking spaces became too small for many vehicles. The decrease in business eventually resulted in the Capital Garage closing in 1973. The building was imploded the following year, but several of the bas-reliefs were saved and donated to the Smithsonian's National Museum of American History. The site now houses the Inter-American Development Bank office building.
History
Construction and design
During the 1920s, with the advent of increased car ownership, there was a serious need for additional parking in downtown Washington, D.C. In 1926, real estate firm Shannon & Luchs purchased the building at 1302 New York Avenue NW, which formerly housed the Halls of the Ancients, a museum focused on ancient art and architecture that was built in 1898 and closed in 1905. The building was demolished, and construction soon began on a new parking garage, reportedly the largest parking structure in the country. Shannon & Luchs selected a construction company owned by James Baird to build the garage.
The firm hired local architect Arthur B. Heaton (1875-1951) to design the garage. Heaton had already designed numerous commercial and residential buildings in the city, including the Equitable Bank Building, Riggs National Bank, Corcoran Hall, Stockton Hall, The Augusta, The Highlands (now the Churchill Hotel), and would later design the Park and Shop, the nation's first planned neighborhood shopping center which was also developed by Shannon & Luchs. Heaton was an avid car enthusiast and received one of the city's first driving permits in 1900. His interest in cars was reflected in the exterior design features of the Capital Garage.
The total cost for the building project, including land and construction, was around $2,000,000. The Capital Garage was designed in the Streamline Moderne architectural style with Gothic Revival details. It was built on the 1300 block of New York Avenue NW where it intersects with 13th and H Streets. The angular shape of the lot resulted in the garage being constructed in three sections with each facing a different angle. The concrete and granite façade featured large windows on the third through tenth floors and ornamental details including sculptures flanking the main entrance depicting winged wheels below a 1926 automobile with 1926 license plates, stone bas-reliefs on the second floor depicting headlights and radiator grilles, and lion-headed grotesques below the roof line. The sides and rear of the building, which included ten floors, including a two-level basement and 20 parking levels, were mostly lined with large windows. The total frontage on New York Avenue was , and the building was wide.
The interior space measured which included parking spaces for 1,200 automobiles, a number which would have been surpassed by Frank Lloyd Wright's Crystal Heights complex near Dupont Circle had Lloyd's design been built. In addition to operating as a parking garage, the building included an Amoco gas station, automobile repair shop, carwash, and retail space including a cigar store. There were 20 ramps inside the garage, measuring wide, with separate ramps for automobiles driving either up or down the structure. The incline of the ramps was compared to driving north on 16th Street NW in the area of Meridian Hill Park.
Operations
To promote the opening of the Capital Garage, owners organized a contest whereby car dealerships would have someone drive their automobiles to the top of the building, with the fastest time winning the race. The contest was held on March 12, 1927, with hundreds of spectators. A reporter for The Washington Post wrote, "The purpose of the contest, officials of the garage said, was two-fold: to allow the dealers to come to the garage and demonstrate the climbing power of their cars, and to introduce to the public the facilities of the new garage." The winning driver, King Richardson, completed the task in 1 minute and 29 seconds in a new Studebaker. He beat E.N. Wallace, who drove a Peerless Model 6-90, by five seconds. The Post reported, "The contest of course convinced none of the participants as to which car could climb the best. It was claimed that it was in large measure the ability of the driver and not the car, which decided the winner."
When the Capital Garage opened in March 1927, customers could pay 25 cents to park for the first two hours or $5 weekly. The garage proved popular with area businesses including the Woodward & Lothrop and Palais Royal department stores, who would often entice customers by paying their parking costs or offering valet services. By the 1930s around 75 people were employed at the Capital Garage. For three years during World War II General Philip Bracken Fleming authorized the federal government leasing the building for $500,000, which was later criticized by former Interior Secretary Harold L. Ickes. The garage was used to house government vehicles as well as storage space for documents.
After the war, the Capital Garage was remodeled, and in 1947 a Nash Motors dealership opened in the building. Two years later a fundraiser for the Metropolitan Police Boys' Club was held at the garage. The fundraiser involved a black 1941 Mercedes-Benz 770 limousine described as "Hitler's Car" being put on display. Hitler had only ridden in the car twice, and it was given as a gift to Finnish Field Marshal Carl Gustaf Emil Mannerheim after Finland became allies with Nazi Germany.
In the 1950s the Nash dealership was replaced by Chrysler and a secondary parking lot was added at 1714 F Street NW. As the size of automobiles increased from the 1940s to 1960s, the parking spots in the Capital Garage were often too small for the wide-bodied vehicles. Journalist Charles McDowell Jr. wrote about the struggles of parking in the garage, calling it an "adventure every work day." For a reduced rate, customers could park their own vehicles, which McDowell described as "squeezing past the monsters so swollen through the years." A parking space once suitable for a Packard no longer sufficed for modern vehicles, which would sometimes take up two-and-a-half spaces. He also described the once-grand lobby where valet drivers would wait for customers and reminisce about the garage's "glory days," when the building was always busy; employees could tell the social status of customers by the level on which their car was parked. Notable people who once used the facility include Jacqueline Kennedy Onassis and Shirley Temple.
Closing and demolition
As the building grew older and parking became more difficult in the garage, business declined, and the Capital Garage closed in November 1973. The building that The Book of Washington once called a "splendid institution" and a "distinct contribution to the beauties of Washington" was demolished by car parking company PMI two months later. On January 5, 1974, 600 pounds (272 kg) of dynamite was used to implode the Capital Garage with the front wall falling last. There was reportedly no damage to any surrounding buildings. There would not be another implosion in the city until 2004 when the Washington Convention Center was demolished.
Because the front wall of the Capital Garage was largely intact after the implosion, some of the architectural features that adorned the façade were saved. The bas-reliefs that were recovered, which Robert M. Vogel of the Smithsonian Institution said survived "quite well" and "the only break was in one tire, just chips," were donated to the Smithsonian's National Museum of American History. The Smithsonian notes "only the iconic sculptures remain to mark the pomp and grandeur that helped to usher in the automobile age in Washington." Both McDowell and author James M. Goode, a Smithsonian Institution historian, suggested the Capital Garage would have likely been saved if it had survived a few more years due to the increased popularity of historic preservationism.
The garage's site remained undeveloped until 1981, when the Daon Development Corporation paid $615 a square foot, a record price in the city, for the New York Avenue property. The Daon Building, designed by architect David Childs, was constructed on the site three years later. The 720,000 square-foot (66,890 sq m) office building is twice the size of the Capital Garage and houses the Inter-American Development Bank.
References
External links
Buildings and structures demolished in 1974
Commercial buildings completed in 1927
Commercial buildings in Washington, D.C.
Demolished buildings and structures in Washington, D.C.
Garages (parking) in the United States
Gothic Revival architecture in Washington, D.C.
Streamline Moderne architecture in Washington, D.C.
Buildings and structures demolished by controlled implosion | Capital Garage | [
"Engineering"
] | 1,971 | [
"Buildings and structures demolished by controlled implosion",
"Architecture"
] |
70,322,089 | https://en.wikipedia.org/wiki/Spenolimycin | Spenolimycin is a spectinomycin-type antibiotic which has been isolated from the bacterium Streptomyces gilvospiralissp. Spenolimycin has the molecular formula C15H26N2O7.
References
Further reading
Spenolimycin
Antibiotics
Oxygen heterocycles
Secondary amines
Methoxy compounds
Diamines | Spenolimycin | [
"Chemistry",
"Biology"
] | 78 | [
"Antibiotics",
"Biocides",
"Biotechnology products"
] |
70,322,115 | https://en.wikipedia.org/wiki/List%20of%20alpine%20climate%20locations | A number of locations around the Earth have alpine climate. The climate of some of these locations is described, below.
For tropical oceanic locations, such as the summit of Mauna Loa, elev. , the temperature is roughly constant throughout the year:
For mid-latitude locations, such as Mount Washington in New Hampshire, the temperature varies seasonally, but never gets very warm:
Other examples of alpine climate include
References
Mountain meteorology
Alpine climate locations
Alpine climate locations | List of alpine climate locations | [
"Physics"
] | 95 | [
"Weather",
"Physical phenomena",
"Weather-related lists"
] |
70,322,404 | https://en.wikipedia.org/wiki/Actinobolin | Actinobolin is a antibiotic with the molecular formula C13H20N2O6. Actinobolin is produced by the bacterium Streptomyces griseoviridus var atrofaciens.
References
Further reading
Antibiotics
Lactones
Amides
Isochromenes | Actinobolin | [
"Chemistry",
"Biology"
] | 60 | [
"Biocides",
"Biotechnology products",
"Functional groups",
"Organic compounds",
"Antibiotics",
"Amides",
"Organic compound stubs",
"Organic chemistry stubs"
] |
70,322,649 | https://en.wikipedia.org/wiki/Fumigatonin | Fumigatonin is a meroterpenoid of the fungi Aspergillus fumigatus with the molecular formula C28H38O11.
References
Further reading
Heterocyclic compounds with 6 rings
Acetate esters
Lactones | Fumigatonin | [
"Chemistry"
] | 54 | [
"Organic compounds",
"Organic compound stubs",
"Organic chemistry stubs"
] |
70,322,768 | https://en.wikipedia.org/wiki/Topical%20fluoride | Topical fluorides are fluoride-containing drugs indicated in prevention and treatment of dental caries, particularly in children's primary dentitions. The dental-protecting property of topical fluoride can be attributed to multiple mechanisms of action, including the promotion of remineralization of decalcified enamel, the inhibition of the cariogenic microbial metabolism in dental plaque and the increase of tooth resistance to acid dissolution. Topical fluoride is available in a variety of dose forms, for example, toothpaste, mouth rinses, varnish and silver diamine solution. These dosage forms possess different absorption mechanisms and consist of different active ingredients. Common active ingredients include sodium fluoride, stannous fluoride, silver diamine fluoride. These ingredients account for different pharmacokinetic profiles, thereby having varied dosing regimes and therapeutic effects. A minority of individuals may experience certain adverse effects, including dermatological irritation, hypersensitivity reactions, neurotoxicity and dental fluorosis. In severe cases, fluoride overdose may lead to acute toxicity. While topical fluoride is effective in preventing dental caries, it should be used with caution in specific situations to avoid undesired side effects.
Medical uses
Topical fluoride formulations are effective measures for preventing and arresting the progression of dental caries, especially early childhood caries (ECC). Domestic products such as toothpaste and mouthwash can be used on a regular basis at home, while silver diamine solution therapy can be administered by specialists in dental clinics.
Mechanism of action
Topical fluoride serves to prevent early dental caries primarily in three ways: promoting remineralization of decalcified enamel, inhibiting the cariogenic microbial processes in dental plaque and increasing tooth resistance to acid breakdown.
Promotion of remineralization of decalcified enamel
Fluoride has a high tendency to react with the calcium hydroxyapatite Ca10(PO4)6(OH)2 in tooth enamel due to its high affinity to metals. It subsequently replaces the hydroxide group in hydroxyapatite to precipitate calcium fluorapatite Ca5(PO4)3)F. These fluorapatite precipitations scavenge excess phosphate and calcium in the saliva to form a supersaturated solution for remineralization.
Inhibition of the cariogenic microbial processes in dental plaque
Topical fluoride also serves as an antimicrobial agent to reduce demineralization by inhibiting the growth of tooth-erupting microorganisms in dental plaque. Fluoride ions readily combine with hydrogen cations to produce hydrogen fluoride. Hydrogen fluoride subsequently acidifies the bacterial cytoplasm, inactivating the essential enzymes for bacterial metabolism, including enolase and proton releasing adenosine triphosphatase.
As topical fluoride lowers the pH, bacteria have to consume more energy to maintain a neutral environment, leaving less energy for reproduction, and further generation of polysaccharides and acids. These polysaccharides are necessary for adherence to enamel, while these acids are essential for the synthesis of bacterial enzymes, for example, immunoglobulin A protease. These processes contribute to reducing the risk of dental caries by inhibiting microbial metabolism in the tooth plaque.
Increase in tooth resistance to acid dissolution
Topical fluoride can increase the resistance of enamel to acid. Bacteria in enamel, including Streptococcus mutans, generate acids to maintain a low pH environment during fermentation. These acids eventually dissociate the hydroxyapatite in teeth once the acidity falls below the critical pH (pH 5.5). The fluorapatite formed by topical fluorides has lower critical pH (pH 4.5) than normal enamel, it is therefore more acid resistant and not prone to degrade even in an acidic environment. This mechanism helps decelerate the rate of teeth demineralization.
Dosage forms
Toothpaste
The daily use of fluoride-containing toothpaste is recognized as the key factor contributing to the global reduction in dental caries over recent decades. Fluoride-containing toothpaste can be classified into two types, namely low-fluoride and high-fluoride toothpaste. Low-fluoride toothpaste, depending on brand, generally contains 0.22% to 0.31% fluoride. These fluorides are often manufactured in the form of sodium fluoride, stannous fluoride, or sodium monofluorophosphate (MFP). High-fluoride toothpaste typically contains 1.1% sodium fluoride, namely four times more concentrated than low-fluoride toothpaste. People using high-fluoride toothpaste should avoid eating or rinsing their mouth for at least 30 minutes after treatment for maximal therapeutic effect. Some fluoride-containing toothpaste incorporates extra chemical ingredients for additional purposes. For instance, calcium carbonate and magnesium carbonate are added as abrasives to remove dental plaque on teeth, while strontium chloride and potassium nitrate are added as anti-sensitive agents for individuals who have teeth sensitivity.
Mouth rinse
Fluoride mouth rinse is usually used for adjunctive therapy with other topical fluoride products. It is generally prepared in the form of sodium chloride. Sodium chloride is kept in the saliva after spitting out the mouth rinse, thus helping to prevent tooth decay. 0.02% fluoride mouth rinse is commonly administered twice daily, while 0.05% is administered once daily at bedtime after thoroughly brushing teeth. People using high-fluoride toothpaste should avoid eating or rinsing their mouth for at least 30 minutes after administration for maximal therapeutic effect.
Silver diamine solution
Silver diamine fluoride (SDF) is a transparent solution which is prepared by dissolving silver ions and fluoride ions into ammonia water. It is approved by professionals to prevent early childhood caries (ECC) and relieve tooth sensitivity.
SDF has multiple advantages over traditional fluoride varnish therapy:
SDF is a non-invasive treatment which makes it more acceptable to children and the elderly.
The materials required for SDF are inexpensive, reducing the financial burden on patients.
There is currently no evidence that SDF causes serious adverse reactions, for example, acute toxicity and infection of the dental pulp, rendering it a safer therapy.
SDF followed by stannous fluoride has been proven to be more effective in reducing dental caries in children's primary molars.
However, the SDF solution results in permanent black staining on the teeth's decayed proportion. This may be unacceptable by some individuals with aesthetic concerns.
SDF, in addition to performing the functions of conventional topical fluorides, is said to have collagen-conserving properties and an additional antibacterial action owing to the presence of silver. While multiple clinical trials demonstrate that 38% SDF is more effective than 5% sodium fluoride varnish in preventing ECC, it is currently unavailable in many countries due to insufficient research data.
Adverse effects
Increased exposure of fluoride may lead to certain adverse side effects, including dental fluorosis and developmental neurotoxicity. Other rare side effects include skin rash and hypersensitivity reactions. In severe cases, fluoride overdose may lead to acute toxicity.
Dental fluorosis
Dental fluorosis is a dose-dependent adverse drug effect featured by temporary white marks. It can be induced by increased fluoride exposure, typically from stannous fluoride-containing products or fluoridated water. Excess intake of fluoride leads to overabundance of structurally-weak fluorapatite formed inside the enamel, resulting in increased brittleness of teeth. In severe dental fluorosis, brown or yellow staining may appear on teeth. Children under the age of eight are susceptible to dental fluorosis.
Developmental neurotoxicity
Overdose of fluoride can potentially cause neurotoxicity during early development. While the exact pathophysiology of fluoride-induced developmental toxicity is not completely understood, most research suggested that excessive fluoride intake may result in formation of aluminium fluoride (AlF3 or AlF4). Aluminium fluoride structurally mimics phosphate, thus is capable of crossing the blood-brain barrier via phosphate transporters. These fluorides in the brain may cause neurodegenerative disorders, including Alzheimer's disease, Parkinson's disease and IQ declination. Nevertheless, topical fluoride was less likely to cause developmental neurotoxicity than fluoridated water.
Acute fluoride toxicity
Fluoride overdose may cause acute toxicity. While the underlying mechanism of fluoride toxicity is unclear, most studies ascribe fluoride toxicity to its capacity to inhibit metalloproteins by imitating metallofluoride substrate. Inhibition of metalloproteins slows down multiple signalling pathways and disrupts cellular organelles, subsequently producing oxidative stress and cell cycle arrest. Fluoride overload is suggested to be linked to pH and electrolyte imbalances, creating an environment unfavourable for cell living. These mechanisms can ultimately result in cellular malfunction and cell death.
Cautions
Toothpaste, cream, mouthrinse and varnish
Most topical fluoride preparations with a concentration exceeding 0.6 ppm should be avoided to reduce risk of dental fluorosis if drinking water has already been fluoridated.
Swallowing of topical fluoride products should be avoided in order to avoid systemic adverse effects, for example, skeletal fluorosis.
While an appropriate amount of fluoride consumption during pregnancy is beneficial to prevent early childhood caries (ECC), pregnant women should avoid excessive fluoride exposure since it may predispose their children to skeletal fluorosis in later childhood.
Most topical fluoride preparations containing more than 1.1ppm should be avoided in children younger than 6 years of age, unless otherwise instructed by a healthcare practitioner.
Topical fluoride preparation containing benzyl alcohol derivative, polysorbate 80 and propylene glycol should be used in caution. These ingredients may precipitate severe adverse effects in neonates.
Silver diamine fluoride
Silver diamine fluoride is contraindicated in patients having silver allergy, oral ulcerations and severe gum disease. These diseases can cause painful responses when associated with the acid or ammonia in SDF.
References
Fluorides
Dentistry
Dental drugs
Tooth decay | Topical fluoride | [
"Chemistry"
] | 2,201 | [
"Fluorides",
"Salts"
] |
70,322,792 | https://en.wikipedia.org/wiki/Phlebiarubrone | Phlebiarubrone is an antibiotic with the molecular formula C19H12O4 which is produced by the fungi Punctularia strigosozonata.
References
Further reading
antibiotics
Benzodioxoles | Phlebiarubrone | [
"Chemistry",
"Biology"
] | 48 | [
"Antibiotics",
"Biocides",
"Biotechnology products"
] |
70,323,727 | https://en.wikipedia.org/wiki/Phalaenopsis%20%C3%97%20valentinii | Phalaenopsis × valentinii is a species of orchid native to peninsular Malaysia. It is a natural hybrid of Phalaenopsis violacea and Phalaenopsis cornu-cervi.
Taxonomy
It has been placed within the section Stauroglottis by Robert Allen Rolfe. Its hybrid nature was unknown in this placement.
References
valentinii
Orchid hybrids
Hybrid plants
Plant nothospecies
Interspecific plant hybrids | Phalaenopsis × valentinii | [
"Biology"
] | 89 | [
"Hybrid plants",
"Plants",
"Hybrid organisms"
] |
70,323,799 | https://en.wikipedia.org/wiki/Phalaenopsis%20%C3%97%20singuliflora | Phalaenopsis × singuliflora is a species of orchid native to Borneo. It is a natural hybrid of Phalaenopsis bellina and Phalaenopsis sumatrana. Its name singuliflora is derived from the consecutively produced flowers.
Taxonomy
It has been viewed as a synonym of Phalaenopsis × gersenii. This natural hybrid however involves Phalaenopsis violacea and Phalaenopsis sumatrana.
References
singuliflora
Orchid hybrids
Hybrid plants
Plant nothospecies
Interspecific plant hybrids
Plants described in 1932
Orchids of Borneo | Phalaenopsis × singuliflora | [
"Biology"
] | 121 | [
"Hybrid plants",
"Plants",
"Hybrid organisms"
] |
70,324,823 | https://en.wikipedia.org/wiki/The%20Poem%20of%20Angkor%20Wat | The Poem of Angkor Wat (ល្បើកអង្គរវត្ត Lpoek Angkor Vat or Lbaeuk Ângkôr Vôtt), is a Khmer poem which dates from the beginning of the 17th century. It celebrates Angkor Wat, the magnificent temple complex at Angkor and describes the bas-reliefs in the temple galleries that portray the Reamker. The Poem of Angkor Wat is considered to be the earliest original literary work in Khmer language. It is one of the two great epic poems of Cambodia with the Reamker in the style of the Indian epic poetry.
Summary
The Poem of Angkor Wat is the story of a certain prince Ketumala, son in a previous existence to the god Indra, who cannot stay in the gods' realm because his human smell is unbearable to the devata. Out of compassion for his exiled son, Indra sends his personal architect, Preah Pisnukar (or Braḥ Bisṇukār, Vishvakarman) to the earth to build a palace for Ketumala in the human realm.
Preah Pisnukar supervises and organizes servants from all over the world to build the palace. Preah Pisnukar orders the clearing of the forest around Phnom Bakheng, and the bringing of high quality stones to construct the complex. Once the works are completed, Preah Ketmealea enters his new palace namely Intapras, where he rules as the great king (Mahārāja, or Mohareach).
Analysis
Versions
The version of The Poem of Angkor Wat was originally inscribed on the temples of Angkor Wat and was first written in modern script in 1878 by the French khmerologist Étienne Aymonier as "Edification d'Angkor Vat ou Satra de Prea Kêt Mealéa" (sic). Later in 2009, Sokha Thoum, Horm Chhayly, and Hay Vanneth reorganized into modern, easier-to-read scripts, including a glossary for interpreting the ancient words used in the poem.
Date and authorship
According to khmerologist Grégory Mikaelian, The Poem of Angkor Wat is a cosmogonic text of a new literary genre wanted by the royal government of Oudong engaged in a cycle of refoundation of power following the fall of their capital Longvek conquered by the Siamese in 1594.
Variously dated 1598 and 1620, a philological study of The Poem of Angkor Wat by Pou Saveros has established its date of composition as 1620 AD and attributed its authorship to a certain Pang Tat, called Neak Pang.
Style
The Khmer poem is rich in alliterative and rhyming words. The poem is long and uses three different meters: Bat Prohmkoet, Bat Kakketi, and Bat Pomnol. According to Pou Saveros, much of it defies any intelligence, which contrasts with the clarity of Khmer inscription IMA 38 known as the "great inscription of Angkor".
Shifting memories
The Poem of Angkor Wat is a witness to the cultural shift of Cambodia after the fall of Longvek and reflects the "harmonization of [the] Brahmanic heritage and Theravada ideology."
One of the main characters, Ketumala, corresponds to King Suryavarman II, in the first half of the twelfth century, the real builder of Angkor Wat, but at the time of composition the poem in the seventeenth century, Suryavarman II had already vanished from people's minds.
Influence
An archeological trace in Khmer literature: celebrating the beauty of Angkor Wat
The Story of Angkor Wat which dates from the beginning of the 17th century, celebrates the magnificent temple complex at Angkor and describes the bas-reliefs in the temple galleries that portray the Rāma story. The epic eulogizes the glory of Cambodian rulers and celebrates the beauty of their palace, Angkor Wat.
Preah Pisnukar, main hero of the poem, is still invoked as a patron by carpenters, artists and builders in Cambodia as the legendary builder of Angkor Wat. He has also been invoked by alien theorists.
A landmark of Khmer literature
The Poem of Angkor has had a lasting influence on Khmer culture and literature.
Etiologically, the main characters of the poem have also given their name to the geography of Siemreap: the name Ketmealea is the basis for the name of the monument Beng Mealea, the modern Buddhist pagoda Wat Beng Mealea, and the village and commune Phum Beng Mealea, which is located in the Svay Leu district, Siem Reap province. It was also chosen for the name of the Preah Ket Mealea Hospital in Phnom Penh.
To this day, The Poem of Angkor is often referred to by Khmer people, in popular plays and pastiche, as well as in the Royal Ballet of Cambodia.
A masterpiece of poetry
The Poem of Angkor Wat reveals the poetic potential of the ruins of Angkor Wat. This poetic potential was reflected in the works by generations of bards and poets, both Khmer and foreign, such as American poet Allen Ginsberg's "Ankor Wat", one of the most significant evocations of the Khmer temples in modern literature.
The legend of Angkor is not just a coincidence. It illustrates one of the most beautiful popular creations, not coming out of nothing, but composed from elements belonging to several different traditions, an Indian Hindu tradition and a Southeast Asian Buddhist tradition. According to Saveros Pou, the talent of the poets did the rest, rooting the legend in the heart of the Khmer people: it borders on genius.
References
Bibliography
1620 poems
Epic poems
Cambodian literature
Performing arts in Cambodia
Works based on the Ramayana
Cosmogony
Angkor Wat | The Poem of Angkor Wat | [
"Astronomy"
] | 1,184 | [
"Cosmogony"
] |
70,324,833 | https://en.wikipedia.org/wiki/Mate%20choice%20in%20humans | In humans, males and females differ in their strategies to acquire mates and focus on certain qualities. There are two main categories of strategies that both sexes utilize: short-term and long-term. Human mate choice, an aspect of sexual selection in humans, depends on a variety of factors, such as ecology, demography, access to resources, rank/social standing, genes, and parasite stress.
While there are a few common mating systems seen among humans, the amount of variation in mating strategies is relatively large. This is due to how humans evolved in diverse niches that were geographically and ecologically expansive. This diversity, as well as cultural practices and human consciousness, have all led to a large amount of variation in mating systems. Below are some of the overarching trends of mate choice.
Female mate choice
Although human males and females are both selective in deciding with whom to mate, females exhibit more mate choice selectivity than males, as is seen in nature. Relative to most other animals however, female and male mating strategies are found to be more similar to each other. According to Bateman's principle of Lifespan Reproductive Success (LRS), human females display the least variance of the two sexes in their LRS due to their high obligatory parental investment, that is a nine-month gestational period, as well as lactation following birth in order to feed offspring so that their brain can grow to the required size.
Human female sexual selection can be examined by looking at ways in which males and females are sexually dimorphic, especially in traits that serve little other evolutionary purpose. For example, male traits such as the presence of beards, overall lower voice pitch, and average greater height are thought to be sexually selected traits as they confer benefits to either the women selecting for them, or to their offspring. Experimentally, women have reported a preference for men with beards and lower voices.
Female mate choice hinges on many different coinciding male traits, and the trade-off between many of these traits must be assessed. The ultimate traits most salient to female human mate choice, however, are parental investment, resource provision and the provision of good genes to offspring. Many phenotypic traits are thought to be selected for as they act as an indication of one of these three major traits. The relative importance of these traits when considering mate selection differ depending on the type of mating arrangement females engage in. Human women typically employ long-term mating strategies when choosing a mate, however they also engage in short-term mating arrangements, so their mate choice preferences change depending on the function of the type of arrangement.
Mating strategies
Female short-term
David Buss outlines several hypotheses as to the function of women's short-term mate choices:
Resource hypothesis: Women may engage in short-term mating in order to gain resources that they may not be able to gain from a long-term partner, or that a long-term partner may not be able to provide consistently. These resources may be food, protection for the woman and her children from aggressive men who may capture or sexually coerce them, or status, by providing the woman with a higher social standing. Women may also benefit from having several short-term mating arrangements through paternity confusion—if the paternity of her offspring is not certain, she may be able to accrue resources from several men as a result of this uncertainty.
Genetic benefit hypothesis: Women may choose to engage in short-term mating arrangements in order to aid conception if her long-term partner is infertile, to gain superior genes to those of her long-term partner, or to acquire different genes to those of her partner and increase the genetic diversity of her offspring. This relates to what is known as the sexy son hypothesis; if a woman acquires genes from a high quality male, her offspring will likely have higher mate value, resulting in their increased reproductive success.
Mate expulsion and mate switching: Women may engage in a short-term mating arrangement in order to cause an end to a long-term relationship; in other words, to facilitate a break-up. Women may also use short-term mating if their current partner has depreciated in value, and they wish to 'trade up' and find a partner that they believe has higher value.
Short-term for long-term goals: Women may use short-term sexual relationships in order to assess a mate's value as a long-term partner, or in the hopes that the short-term arrangement will result in one that is long-term.
Female long-term
The provision of economic resources, or the potential to acquire many economic resources, is the most obvious cue towards the ability of a man to provide resources, and women in the United States have been shown experimentally to rate the importance of their partner's financial status more highly than men. However, many other traits exist that may act as cues towards a man's ability to provide resources that have been sexually selected for in women's evolutionary history. These include older age—older males have had more time to accrue resources—industriousness, dependability and stability—if a woman's long-term partner is not emotionally stable or is not dependable then their provision of resources to her and her offspring are likely to be inconsistent. Additionally, the costs associated with an emotionally unstable partner such as jealousy and manipulation may outweigh the benefits associated with the resources they are able to provide.
Women's mate choices will also be constrained by the context in which they are making them, resulting in conditional mate choices. Some of the conditions that may influence female mate choice include the woman's own perceived attractiveness, the woman's personal resources, mate copying and parasite stress. Romantic love is the mechanism through which long-term mate choice occurs in human females.
Male short-term
When finding a short-term mate, males highly value women with sexual experience and physical attractiveness. Men seeking short-term sexual relationships are likely to avoid women who are interested in commitment or require investment. In short-term sexual relationships, men are less choosy because of low parental investment.
Examples of short-term mating strategies in males:
Multiple sexual partners: When looking for short-term sexual relationships, men may wish for there to be as little time as possible between each partner.
Physical attractiveness: Men who are interested in a short-term sexual relationship are more likely to prioritise information about the body of potential partners, rather than their faces. When finding a female for a short-term relationship, compared with a long-term relationship, males are less likely to prioritise factors such as commitment.
Relaxation of standards: It has been reported that men are more likely to engage in a sexual relationship with women who have lower levels of intelligence, independence, honesty, generosity, athleticism, responsibility and cooperativeness, when this relationship is short-term. Men may be more accepting of lower standards, than what they usually prefer, because they are not entering a long-term relationship with this person.
Sexual experience: Many men assume that women who have engaged in sexual experiences beforehand are likely to have a higher sex drive than women who haven't. These women may also be more accessible and require less courtship.
Male long-term
Humans have the ability to rely on biological signals of reproductive success and non-biological signals, such as the female's willingness to marry. Unlike many animals, humans are not able to consciously display physical changes to their body when they are ready to mate, so they have to rely on other forms of communication before engaging in a consensual relationship. Romantic love is the mechanism through which long-term mate choice occurs in human males. For long-term sexual relationships, men are usually equally choosy because they have a similar parental investment like the women, as they heavily invest in the offspring in form of resource provisioning.
Males may look for:
Commitment and marriage: A human male may be interested in mating with a female who seeks marriage. This is because he has exclusive sexual access to the female, so any offspring produced in the relationship will be genetically related to him (unless the female has sexual intercourse with another male outside of the marriage). This increases the likelihood of paternity certainty. With two married parents investing in the offspring, their chance of survival may increase; therefore the male's DNA will be passed on to the children of his offspring. Also, a male who is interested in committing to a female may be more attractive to potential mates. A male who can promise resources and future parental investment is likely to be more appealing to women than a male who is unwilling to commit to her.
Facial symmetry: Symmetrical faces have been judged to signal good general health and the ability for a woman to withstand adverse environmental factors, such as illness.
Femininity: A feminine face can be a signal of youth, which in turn signals strong reproductive value. As a woman gets older, her facial features become less feminine due to ageing. Femininity can also be linked to disease-resistance and high estrogen levels, which are factors that suggest reproductive value to a potential mate.
Physical beauty: Observable characteristics of a woman can indicate good health and the ability to reproduce, qualities which are likely to be desired by a male. This may include smooth skin, absence of lesions, muscle tone, long hair and high energy levels. Women with darker features (lips, eyes, eyebrows) relative to their facial skin have been found to be more attractive, as this increases facial contrast (the same features appear to decrease male attractiveness).
Waist-to-hip ratio: A waist-to-hip ratio of 0.7 is an indicator of fertility, lower long-term health risks and suggests that the woman isn't already pregnant. A male is likely to desire these qualities in a mate, as it will increase the chance of survival of any offspring the couple have together.
Breasts: The pigmentation of nipples and breasts appears to be the most important quality of breast attractiveness. Men rated women with dark nipples and dark areola as significantly more attractive than those with light-colored nipppes or areola. Breasts of medium cup size were found to be the most attractive, however authors noted that men focused primarily on the coloration of nipples and areola rather than breast size.
Youth: Both young and old men are attracted to women in their twenties. Faces that appear younger are usually rated as more attractive by males.
Parasite stress on mate choice
The parasite-stress theory, otherwise known as pathogen stress, states that parasites or diseases put stress on the life development of an organism, leading to a change in the appearance of their sexually attractive traits. The initial research on the Hamilton–Zuk hypothesis (see indicator traits) showed that, within one species (brightly colored birds), there was greater sexual selection for males that had brighter plumage (feathers). In addition, Hamilton and Zuk showed that, comparing across multiple species, there is greater selection for physical attributes in species under greater parasitic stress. This has influenced research regarding human mate choice.
In societies with a high prevalence of parasites or pathogens, members would derive greater evolutionary advantage from selecting for physical attractiveness/good looks in mate choice compared to that derived by members of societies with lower prevalence. Humans could use physical attractiveness to determine resistance to parasites and diseases, which are believed to lower their sufferers' ability to portray attractive traits from then on and limit the number of high-quality pathogen-resistant mates. In cultures where parasitic infection is especially high, members could use cues available to them to determine the physical health status of the potential mate. Regardless of the wealth or ideology, the females in areas that are more at risk or have higher rates of parasites and diseases would weigh masculinity more highly when rating potential mates.
Scarification: In pre-industrial societies, body markings such as tattoos or scarifications are predicted to have been a way in which individuals could attract potential mates, by indicating the reproductive quality of a person. Meaning, scars on the body could be viewed by prospective mates as evidence that a person has overcome parasites and is thus more attractive to potential mates. Research investigating this hypothesis (Singh and Bronstad 1997) found that in instances of increased pathogen prevalence, the only anatomical area with evidence of scarification in females was found on the stomach, with no evidence found for male scarification.
Masculinity: In societies where there are high levels of parasites or diseases, the females, as the overall health of members decreases, are predicted to increasingly emphasize masculinity in their mate preferences. Women look for signs of masculinity in areas such as the voice, face and body shape of males. The face, in particular, may hold several cues for parasitic resistance and has been the subject of most attractiveness research.
Polygamy: Tropical areas were originally associated with polygynous societies as a result of the surrounding environment being both ecologically richer and homogeneous. However, whilst tropical areas were associated with polygamy, pathogen stress is predicted as a better indicator of polygamy and has been positively correlated with it. Furthermore, over the course of human evolution, areas which had high levels of parasite-stress may have shifted the polygamy threshold and increased the presence of certain types of polygamy in a society.
Criticisms
Gangested and Buss (2009) say that research indicates that parasite stress may have only influenced mate choice through females searching for "good genes" which show parasite resistance, in areas which have high prevalence of parasites. John Cartwright also points out that females may be simply avoiding the transmission of parasites to themselves rather than it being them choosing males with good genes and that females look for more than just parasite-resistant genes.
MHC-correlated mate choice
Major histocompatibility complex (MHC) or, in humans, human leukocyte antigen (HLA) produces proteins that are essential for immune system functioning. The genes of the MHC complex have extremely high variability, assumed to be a result of frequency-dependent parasite-driven selection and mate choice. This is believed to be so it promotes heterozygosity improving the chances of survival for the offspring.
Odor preferences
In humans, there is evidence that women will rate men's odor as more pleasant if the odor has MHC-dissimilar antigens, which is proposed as a way of avoiding inbreeding and increasing heterozygosity. However, women on contraceptive pills rate the odor of MHC-similar men as being more pleasant, it is unknown why women on contraceptive pills rate smell in this way. It was found that when processing MHC-similar smells were processed faster. Contrary to these findings, other studies have found that there is no correlation between attraction and odor by testing males' odor preferences on women's odors. The study concludes that there is no correlation in attraction between men and women of dissimilar HLA proteins. Research completed on a Southern Brazilian student population resulted in similar findings that found significant differences in the attraction ratings of giving to male sweat and MHC-difference.
Facial preferences
Human facial preferences have been shown to correlate with both MHC-similarity and MHC-heterozygosity. Research into MHC-similarity with regards to facial attractiveness is limited. One study found that women may prefer mates with MHC-similar faces, despite evidence that they prefer men with dissimilar body odors. While facial asymmetry hasn't been correlated with MHC-heterozygosity, the perceived healthiness of skin appears to be. It appears to be that only MHC-heterozygosity and no other genetic markers are correlated with facial attractiveness in males and it has been shown that so far that there is no correlation that has been found in females. Slightly different from facial attractiveness, facial masculinity is not shown to correlate with MHC heterogeneity (a common measure of immunocompetence).
Criticisms
A review article published in June 2018 concluded that there is no correlation between HLA and mate choice. In addition to assessing previous studies on HLA-Mate choice analysis to identify errors in their research methods (such as small population sizes), the study collects a larger set of data and re-runs the analysis of the previous studies. By using the larger data set to conduct analysis on 30 couples of European descent, they generate findings contrary to previous studies that identified significant divergence in the mate choice with accordance to HLA genotyping. Additional studies have been conducted simultaneously on African and European populations that only show correlation of MHC divergence in European but not African populations.
See also
Human mating strategies
Mating preferences
References
Dating
Evolutionary biology | Mate choice in humans | [
"Biology"
] | 3,421 | [
"Evolutionary biology"
] |
70,325,208 | https://en.wikipedia.org/wiki/J.%20Arthur%20Reavell | James Arthur Reavell (10 June 1872—26 August 1973) M.I.Mech.E., M.I.Chem.E., F.Inst.F., F.I.M. was a British chemical engineer, who created a major company and was one of the founders and a president of the Institution of Chemical Engineers.
Life
Reavell was born 10 June 1872 in Alnwick, the son of George and Martha Reavell. He attended Alnwick Grammar School and Silcoates School.
He married Emma Mabel Clowes on 24 May 1898, and they had two sons, and one daughter. After her death, he married Winifred E. Haydon on 16 August 1941. One of his sons, Brian Noble Reavell, was also a chemical engineer, and took over as chairman when he retired from his business in 1960.
He died 26 August 1973.
Career
He wanted to be a chemist, but instead served an apprenticeship in electrical engineering, and had several positions, rising to be manager for the European operations of an American chemical engineering company Worthington Pumps then manager of Manlove, Alliott & Co. Ltd., dealing with sugar refining, of which a particular aspect is evaporation. In 1907 he set up his own company Kestner Evaporator and Engineering Co., to deal with the British and Empire market of an improved design of evaporator patented by his friend, French inventor Paul Kestner.
During the First World War his engineering expertise was applied to solving the shortage of explosives in a team headed by Lord Moulton.
He continued as Chairman of Kestner until 1960, when he stepped down in favour of his son, Brian, but continued as president until 1963. The company made a variety of chemical plants with subsidiaries in Australia and South Africa.
Institutions
As Chairman of the Chemical Engineering Group of the Society of Chemical Industry (SCI) he was one of the small group of enthusiasts who founded the Institution of Chemical Engineers, becoming its President 1929. He continued to be active in the SCI, being vice-president from 1931 to 1934.
He was also a Member of the Institution of Mechanical Engineers; a Fellow of Institute of Fuel; and a Fellow, Institute of Metals; Chairman of the British Chemical Plant Manufacturers' Association; Chairman of the chemical engineering industry section of the British Standards Institute; and President of the Combustion Appliance Manufacturer's Association from which he formed the British Coal Utilisation Research Association, and was its vice-president.
References
British chemical engineers
People from Alnwick
Institution of Chemical Engineers
1872 births
1973 deaths | J. Arthur Reavell | [
"Chemistry",
"Engineering"
] | 535 | [
"Chemical engineering organizations",
"Institution of Chemical Engineers"
] |
70,326,088 | https://en.wikipedia.org/wiki/Isla%20Verde%20Reef | Isla Verde Reef (Spanish: Arrecife de Isla Verde) is a reef that surrounds Isla Verde Key, located off the coast of Punta del Medio in Isla Verde, Carolina, in the Atlantic coast of Puerto Rico. The Isla Verde Reef, protected as the Isla Verde Reef Marine Reserve (Reserva Marina Arrecife de Isla Verde), forms part of a larger reef system that extends from Punta Maldonado in Piñones, Loíza to the San Juan Islet. This is one of the three designated marine reserves in Puerto Rico, the other two being the Desecheo Coastal Waters and Tres Palmas marine reserves off the western coast of Puerto Rico, and the only one that protects a coral reef ecosystem on an urban area. The reserve is home to endangered species such as manatees, sea turtles and federally protected coral species such as the elkhorn coral. The coral reef is also an ideal place for fish spawning which is important for the fishing industry of the region. The Isla Verde Reef is protected through community organizations such as Arrecifes Pro Ciudad, and public organisms such as Para la Naturaleza (Puerto Rico Conservation Trust), with support from academic institutions such as the University of Puerto Rico at Bayamón.
See also
List of reefs
Protected areas of Puerto Rico
References
External links
Official website
Official website
Coral reefs
Protected areas of Puerto Rico | Isla Verde Reef | [
"Biology"
] | 278 | [
"Biogeomorphology",
"Coral reefs"
] |
70,326,745 | https://en.wikipedia.org/wiki/List%20of%20chlorinated%20propanes | This is a list of the 29 molecules of chlorinated propane in order of number of chlorine atoms.
Monochloro
1-Chloropropane
2-Chloropropane
Dichloro
1,1-Dichloropropane
1,2-Dichloropropane
1,3-Dichloropropane
2,2-Dichloropropane
Trichloro
1,1,1-Trichloropropane
1,2,3-Trichloropropane
1,2,2-Trichloropropane
1,1,2-Trichloropropane
1,1,3-Trichloropropane
Tetrachloro
1,1,1,2-Tetrachloropropane
1,1,1,3-Tetrachloropropane
1,1,2,2-Tetrachloropropane
1,1,2,3-Tetrachloropropane
1,1,3,3-Tetrachloropropane
1,2,2,3-tetrachloropropane
Pentachloro
1,1,1,2,2-Pentachloropropane
1,1,1,2,3-Pentachloropropane
1,1,1,3,3-Pentachloropropane
1,1,2,2,3-Pentachloropropane
1,1,2,3,3-Pentachloropropane
Hexachloro
1,1,1,2,2,3-Hexachloropropane
1,1,1,2,3,3-Hexachloropropane
1,1,1,3,3,3-Hexachloropropane
1,1,2,2,3,3-Hexachloropropane
Heptachloro
1,1,1,2,2,3,3-Heptachloropropane
1,1,1,2,3,3,3-Heptachloropropane
Octachloro
Octachloropropane
References
Chlorinated propanes
Chloroalkanes | List of chlorinated propanes | [
"Chemistry"
] | 487 | [
"nan"
] |
70,327,630 | https://en.wikipedia.org/wiki/Great%20Mill%20Disaster | The Great Mill Disaster, also known as the Washburn A Mill explosion, occurred on May 2, 1878, in Minneapolis, Minnesota, United States. The disaster resulted in 18 deaths. The explosion occurred on a Thursday evening when an accumulation of flour dust inside the Washburn A Mill, the largest mill in the world at the time, led to a dust explosion that killed the fourteen workers inside the mill. The resulting fire destroyed several nearby mills and killed a further four millworkers. The destruction seriously impacted the city's productive capacity for flour, which was a major industry in the city. Following the blast, Cadwallader C. Washburn, the mill's owner, had a new mill, designed by William de la Barre, constructed on the site of the old one. This building was also later destroyed, and today the building's ruins are a National Historic Landmark and operated as part of the Mill City Museum.
Background
In 1874, businessman Cadwallader C. Washburn of La Crosse, Wisconsin, opened the Washburn A Mill in Minneapolis. At the time of its opening, it was the largest industrial building in the city and the largest flour mill in the world. With about 200 employees in 1878, it was also one of the city's largest employers. The mill was located adjacent to several other flour mills along the Mississippi River near the Saint Anthony Falls, where it derived its power from a canal that flowed through the building's lower level. At this time, Minneapolis was a hub of flour production in the United States, having recently surpassed other cities such as St. Louis and Buffalo, New York, in terms of flour productive capacity, with the city popularly referred to as Flour City.
Explosion
At about 6 p.m. on May 2, 1878, the mill's large day shift staff had completed their work for the day and the fourteen-man night shift staff had arrived. At around 7 p.m., three large explosions occurred within several seconds of each other inside the mill, killing the fourteen employees inside. The explosions launched debris several hundred feet into the air, with some large granite debris found eight city blocks from the mill. The sound of the explosion was heard as far away as Saint Paul, a distance of from the mill, while some people in Minneapolis who had felt the blast thought that it had been an earthquake. The explosion spawned a massive fire that spread to two adjacent mills, the Diamond and Humboldt mills, causing both of them to also explode and killing another four millworkers including mill owner Jack Reisman. The intensity of the heat from the blaze hindered firefighting activities, as firefighters could not get close to the buildings, and as a result they continued to fight the fire through the night. The following day, the Minneapolis Tribune reported on the disaster, saying, "Minneapolis has met with a calamity, the suddenness and horror of which it is difficult for the mind to comprehend". In total, six mills were destroyed.
Aftermath
As part of an investigation into the cause of the disaster, mill manager John A. Christian stated that it had been a dust explosion caused by flour dust in the building. Two professors from the University of Minnesota, S. F. Peckham and Louis W. Peck, later confirmed that abundant flour dust had been the cause of the explosion after reviewing controlled experiments regarding flour dust combustion. They concluded that two dry millstones had rubbed against each other and caused a spark that ignited the dust, causing the explosion.
Following the event, there were concerns about the effect it would have on the city's milling industry, as the disaster had destroyed roughly one-third to one-half of the city's flour productive capacity. Shortly after the explosion, Washburn, who had traveled to Minneapolis upon hearing of the incident, announced his intention to rebuild the mill, with technological improvements that would make it safer and increase its productive capacity. Washburn hired Austrian engineer William de la Barre to design the new building, which he based on a mill in Budapest. De la Barre also installed dust collectors and improved ventilation systems. This new building was completed in 1880 on the site of the former building. The reopening coincided with an economic boom for the city, and flour production steadily increased until it peaked during World War I, after which there was a steady industry decline. The new mill (later known as the Gold Medal Flour mill) was affected by a fire in 1928, but following repairs it continued to operate until 1965. The building was later abandoned and finally destroyed in a fire in 1991. In 2003, the building's ruins were converted into the Mill City Museum, a history museum that focuses on the milling history of the city. Today, the ruins are listed on the National Register of Historic Places as a National Historic Landmark.
The MNopedia entry for the disaster states, "It was the worst disaster of its type in the city's history, prompting major safety upgrades in future mill developments". According to General Mills (the eventual successor company of the mill), the disaster prompted Washburn to take an interest in the welfare of the children of the millworkers who had been affected, leading to the creation of the Washburn Memorial Orphan Asylum. Its successor organization, the Washburn Center for Children, continues to operate as a child and family services organization in the Twin Cities area.
Memorials
On the site of the destroyed mill, a stone memorial marker that lists the names of the 14 workers who died at the previous factory was erected as part of a stone portal. The memorial also includes a brief history of the disaster. Today, it is located near the Stone Arch Bridge. In the city's Lakewood Cemetery, a memorial dedicated to the 18 people who died in the disaster was erected in 1885. The memorial includes a plaque that lists the names of the deceased, while the base of the memorial depicts a sheaf of wheat, a broken gear, and a millstone.
See also
Tradeston Flour Mills explosion – A similar dust explosion at a flour mill in Glasgow in 1872
List of industrial disasters
List of industrial disasters by death toll
Notes
References
Further reading
1878 disasters in the United States
1878 in Minnesota
1878 industrial disasters
Disasters in Minnesota
Dust explosions
Events in Minneapolis
Explosions in 1878
Fires in Minnesota
Food processing disasters
History of Minneapolis
Industrial fires and explosions in the United States
Occupational safety and health | Great Mill Disaster | [
"Chemistry"
] | 1,285 | [
"Dust explosions",
"Explosions"
] |
70,328,121 | https://en.wikipedia.org/wiki/Proroxan | Proroxan (INN; also known as pyrroxane and pirroksan) is a pharmaceutical drug used as an antihypertensive and in the treatment of Ménière's disease, motion sickness, and allergic dermatitis.
Proroxan is a non-selective alpha-blocker (α-adrenoreceptor antagonist).
Proroxan was developed in the 1970s at the Institute of Toxicology of the USSR Ministry of Health and today is primarily used in Russia. Though originally developed as an antihypertensive, its use can lead to a decrease in alcohol and drug consumption. Currently proroxan is used almost exclusively in psychiatry, narcology, and neurology.
References
Alpha blockers
Benzodioxans
Pyrrolidines | Proroxan | [
"Chemistry"
] | 168 | [
"Pharmacology",
"Pharmacology stubs",
"Alpha blockers",
"Medicinal chemistry stubs"
] |
70,328,185 | https://en.wikipedia.org/wiki/Cycloheximide%20chase | Cycloheximide chase assays are an experimental technique used in molecular and cellular biology to measure steady state protein stability. Cycloheximide is a drug that inhibits the elongation step in eukaryotic protein translation, thereby preventing protein synthesis. The addition of cycloheximide to cultured cells followed by protein lysis at multiple timepoints is conducted to observe protein degradation over time and can be used to determine a protein's half-life. These assays are often followed by western blotting to assess protein abundance and can be analyzed using quantitative tools such as ImageJ.
Implementation
Cycloheximide chase assays have been conducted using a variety of cell types such as yeast and mammalian cell lines. Depending on the cell system used for analysis, the assay may vary in application and time course. For example, yeast cells expressing a protein substrate of interest typically require cycloheximide chases lasting up to 90 minutes to allow protein turnover to occur. In contrast, proteins that are expressed in mammalian cell lines tend to me more stable at steady state and may require a chase lasting 3 to 8 hours. Depending on the complexity of the protein and whether it is overexpressed or endogenous to the model system, the required length of the chase may vary. To ensure that protein synthesis is inhibited during the entire chase, cycloheximide is often spiked into the sample every few hours.
In yeast, deletion strains are frequently used to assess protein stability over time with cycloheximide chases. For example, yeast strains lacking critical degradation machinery such as chaperones, E3 ligases, and vacuolar proteins are often used to determine the mechanism of degradation for a protein substrate of interest. Drug treatments (such as MG132) are also used to inhibit steps of degradation, followed by a cycloheximide chase to observe how the stability of a protein of interest is affected. These experiments may be conducted in mammalian cells with the implementation of compatible knockdown procedures in place of the yeast deletion strains.
Cycloheximide chases are also valuable for assessing how different mutations affect the stability of a protein. Experiments have been conducted in yeast and mammalian cells to determine the critical residues required for protein stability and how disease-associated mutations may be affecting protein half-lives within the cell. This information is valuable for understanding the complexities of protein folding and how mutations contribute to the pathogenesis of the diseases they are associated with.
Advantages
There are many benefits to using cycloheximide chase assays as opposed to other methods that assess protein stability. Cycloheximide chases can be used with a wide variety of model systems and can be implemented to study almost any protein substrate. Cycloheximide is relatively inexpensive compound compared to other drugs and it is effective when used in low doses for short periods of time. Pulse chase assays are an alternative method to cycloheximide chase assays and involve the radioactive labeling of newly translated proteins followed by a similar “chase” period. While this method is informative and provides the benefit of observing nascent protein abundance, the radioactive material it requires is expensive with a shorter shelf-life and demands more caution to use than cycloheximide.
Disadvantages
Some disadvantages to conducting cycloheximide chase assays include the toxic nature of cycloheximide. When used at high concentrations over a long period of time, cycloheximide will damage the DNA within the cell and impair critical cellular function. For this reason, cycloheximide chases do not typically last for more than 12 hours. This presents a limitation if the turnover of a particularly stable protein is being studied. Additionally, cycloheximide chases only offer the ability to look at steady state proteins levels as opposed to newly translated protein levels such as with pulse chase. Therefore, only protein degradation and not protein maturation is able to be observed.
References
Molecular biology techniques | Cycloheximide chase | [
"Chemistry",
"Biology"
] | 830 | [
"Molecular biology techniques",
"Molecular biology"
] |
70,328,543 | https://en.wikipedia.org/wiki/Overall%20hemostatic%20potential | The overall hemostatic potential (OHP) test is a global coagulation assay which can be used to measure coagulation. The OHP assay measures total fibrin generation in the presence of thrombin or tissue factor and tissue plasminogen activator (t-PA). It generates a fibrin time curve through the use of optical density measurement. This curve represents the balance between fibrin formation induced by thrombin or tissue factor and fibrinolysis induced by t-PA. The assay provides three parameters: overall coagulation potential (OCP), overall hemostatic potential (OHP), and overall fibrinolytic potential (OFP). OHP is the main parameter, while OCP and OFP are supplementary parameters to assess coagulation and fibrinolysis. One further parameter, clot lysis time (CLT), can also be determined. The OHP assay measures the integrated effect of procoagulant, anticoagulant, and fibrinolytic factors.
The OHP is a technically simple but relatively labor-intensive assay. As of 2010, it had been implemented in several laboratories, but was not available commercially. The assay is novel in terms of its combined evaluation of both fibrin generation and fibrinolysis. The test is potentially useful in the evaluation of hypercoagulability, hypocoagulability, and fibrinolytic abnormalities. It is able to detect hypercoagulability associated with pregnancy and estrogen/progestogen hormone therapy. The test has also been used to study coagulation in feminizing hormone therapy in transgender women. However, more studies are needed to validate the test as a biomarker of thrombosis and other abnormalities of coagulation.
History
The original OHP assay was developed in Sweden by Blombäck and colleagues and was first described in 1999. It used thrombin to trigger coagulation. Since then, a modified version has been developed which can use either thrombin or tissue factor to trigger coagulation.
References
Blood tests
Coagulation system
Medical signs | Overall hemostatic potential | [
"Chemistry"
] | 457 | [
"Blood tests",
"Chemical pathology"
] |
70,329,400 | https://en.wikipedia.org/wiki/PITPNM3 | Nir1 or membrane-associated phosphatidylinositol transfer protein 3 (PITPNM3) is a mammalian protein that localizes to endoplasmic reticulum (ER) and plasma membrane (PM) membrane contact sites (MCS) and aids the transfer of phosphatidylinositol between these two membranes, potentially by recruiting additional proteins to the ER-PM MCS. It is encoded by the gene PITPNM3.
Classification
Nir1 has been classically categorized as a class IIA phosphatidylinositol transfer protein (PITP) that transfers phosphatidylinositol (PI) and phosphatidic acid (PA) between membranes. Class IIA PITPs are the multi-domain proteins PITPNM1/Nir2 (Drosophila homolog RdgBaI), PITPNM2/Nir3 (Drosophila homolog RdgBaII).. Nir1 shares high sequence similarity with Nir2 and Nir3, which led to its original categorization as a PITP. However, it was determined that Nir1 is not directly responsible for PI transfer, as it lacks the functional PITP domain seen within Nir2 and Nir3
Localization
Recently, Nir1 has been shown to localize to ER-PM MCS, both under basal conditions and upon phospholipase C (PLC) activation. Notably, PLC activation has previously been shown to regulate the localization of Nir2 and Nir3 at ER-PM MCS well.. The MCS-targeting by Nir1 is achieved by the N-terminus of Nir1 localizing to the ER and the C-terminus of Nir1 localizing to the PM. The domains responsible for binding these membranes are discussed below.
Structure
Nir1 contains three main structural elements that are shared with Nir2 and Nir3: an N-terminal FFAT motif, a DDHD domain, and a C-terminal Lipin/Ndel/Smp2 (LNS2) domain.
FFAT motif
The FFAT motif is made up of double phenylalanines (FF) in an Acidic Tract. This motif, made of residues EFFDA in Nir1, has been shown to be necessary for the Nir proteins to associate with the ER proteins VAPA and VAPB. Mutation of the phenylalanine residues in this motif or knockout of the VAPA and VAPB proteins results in a loss of ER-PM MCS localization and causes Nir1 to become fully localized to the PM.
DDHD domain
The DDHD domain, made up of 3 Asp and 1 His residues, bears some similarities to that seen in PLA1 enzymes, which hydrolyze fatty acids of glycerolphospholipids, including phosphatidic acid (PA). However, this domain is still largely uncharacterized. It is a putative metal binding domain, but a role for metal binding in PITPNM function has not been established
LNS2 domain
The LNS2 domain is the Lipin/Nde1/Smp2 domain. This domain was discovered as having sequence similarities to the phosphatidic acid (PA) binding region found within the Lipin family of proteins. It is also responsible for PA-binding within Nir1, as it has been shown to co-localize with PA biosensors. The LNS2 domain targets the C-terminus of Nir1 to the plasma membrane in order to allow the protein to bridge the ER-PM MCS. Deletion of this domain results in Nir1 localization to the ER. It should be noted however, that the exact domain boundaries of the LNS2 domain are still being debated, especially given the boundaries of the folded domains predicted by the AlphaFold Protein Structure Database. (Alphafold structure of Nir1)
Function
The PITPNM family of proteins has been shown to participate in the phosphoinositide cycle. Lipids cycle between the PM and the ER in order to replenish levels after signaling events deplete lipid species such as PI.. When a stimulus results in the production of PA at the PM, Nir2 and Nir3 move to the ER-PM MCS, where they exchange the PA at the PM for PI that has been produced in the ER. As Nir1 is localized to the ER-PM MCS even without a stimulus, it is thought that Nir1 helps to recruit Nir2 to the MCS. There is evidence that Nir1 recruits Nir2 directly via binding to the uncharacterized domain between the FFAT and DDHD of Nir1
References
Proteins
Endoplasmic reticulum
Membrane biology | PITPNM3 | [
"Chemistry"
] | 1,016 | [
"Biomolecules by chemical classification",
"Proteins",
"Membrane biology",
"Molecular biology"
] |
70,329,538 | https://en.wikipedia.org/wiki/Svetlana%20Zaginaichenko | Svetlana Yurievna Zaginaichenko (, ; 10 August 1957 - 23 November 2015) was a Ukrainian solid state physicist. She studied the physical properties of carbon materials and their application to hydrogen energy storage. She was a nominee for the 2016 Nobel Prize in Chemistry for her work in studying fullerenes.
Education
Zaginaichenko earned a physics degree with honors from Oles Honchar Dnipro National University in 1979.
In 1984, Zaginaichenko defended her dissertation on the physical properties of hexagonally-structured and interstitial alloys at Dnipro Metallurgical Institute, earning the degree of Candidate of Physical and Mathematical Sciences (which is the Soviet equivalent of a Doctor of Philosophy). Her thesis focused on hexagonal close-packed structures and developed theories for impurity solubility, interstitial atom kinetics, and magnetism of such alloys.
Career
From 4 November 1995 until her death in 2015, Zaginaichenko was a leading researcher at the Department for Hydrogen Materials and Carbon Nanostructures at the Institute for Problems of Materials Sciences at the National Academy of Sciences of Ukraine. She was one of the founding members of the Association of Hydrogen Energy in Ukraine (AHEU), which was formed with the support of Turhan Nejat Veziroglu, the president of the International Association of Hydrogen Energy. She was also part of the organizing committee for the International Conference of Carbon Nanomaterials in Clean Energy Hydrogen Systems.
She was nominated for the 2016 Nobel Prize in Chemistry for her work in studying the physical structure of fullerenes and proving that they have three main configurations (isomers). However, she died before the 2016 announcement of the prize, so even if the prize committee had chosen to honor this contribution, the prize's rules against posthumous awards would have prevented her from winning it.
Awards
Yangel Award, State Space Agency of Ukraine and the Federation of Cosmonautics of Ukraine - October 1994
Kondratyuk Medal, State Space Agency of Ukraine and the Federation of Cosmonautics of Ukraine - 23 December 1995
See also
Fullerene
Hydrogen fuel
Turhan Nejat Veziroğlu
References
External links
Zaginaichenko Svetlana Yu. by National Academy of Sciences of Ukraine
Загінайченко Світлана Юріївна by Encyclopedia of Modern Ukraine
Works by Zaginaichenko, S. Yu (Svetlana Yu.) by WorldCat
Institute for Problems of Materials Science at the National Academy of Sciences of Ukraine
International Conference of Carbon Nanomaterials in Clean Energy Hydrogen Systems
Ukrainian women physicists
Condensed matter physicists
20th-century Ukrainian physicists
1957 births
2015 deaths
Oles Honchar Dnipro National University alumni
Scientists from Kyiv
Members of the National Academy of Sciences of Ukraine | Svetlana Zaginaichenko | [
"Physics",
"Materials_science"
] | 582 | [
"Condensed matter physicists",
"Condensed matter physics"
] |
76,107,991 | https://en.wikipedia.org/wiki/UGC%208508 | UGC 8508 is a dwarf irregular galaxy located about 8.5 million light-years away from Earth in the constellation of Ursa Major. It is sometimes classified as a member of the M101 Group of galaxies and has a diameter of around .
As an irregular galaxy, UGC 8508 does not exhibit any large scale organization in its structure. It has a bluish appearance when viewed in the visible spectrum and although it has a large number of H I regions, it has a relatively low-luminosity overall. However, the presence of a significant number of both blue and red supergiant stars indicate it is likely to have undergone a period of rapid star formation in the cosmologically recent past. The distribution of the supergiants suggests that star formation has largely ceased at distances greater than from the center of the galaxy.
References
External links
Irregular galaxies
M101 Group
Ursa Major
08508
47495 | UGC 8508 | [
"Astronomy"
] | 188 | [
"Ursa Major",
"Constellations"
] |
76,109,895 | https://en.wikipedia.org/wiki/TK83 | The TK83 was a home computer produced by the Brazilian company Microdigital Eletrônica Ltda. and introduced in August 1982. By December 1984, it was no longer being advertised by Microdigital, being discontinued in 1985.
The TK83 was a clone of the Sinclair ZX81, and can for all practical purposes, be considered a version of the TK82C with repagged memory and including the SLOW function which permitted the video be shown during processing.
General information
The TK83 had the Zilog Z80A processor running at 3.25 MHz, 2 KB RAM (expandable to 64 KB) and 8 KB of ROM that included the BASIC interpreter.
The keyboard was made of layers of conductive (membrane) material and followed the Sinclair layout with 40 keys.
Video output was sent via a RF modulator to a TV set tuned at VHF channel 3, and featured black characters on a white background. The maximum resolution was 64 x 44 pixels, based on semigraphic characters useful for games and basic images (see ZX81 character set).
There was one expansion slot at the side of the machine, a cassette interface (data storage in tapes at 300 to 4200 baud, with audio cables were supplied with the computer for connection with a regular tape recorder) and a DIN joystick connector.
References
Microdigital Eletrônica
Computer-related introductions in 1982
Goods manufactured in Brazil
Products introduced in 1983
Sinclair ZX81 clones | TK83 | [
"Technology"
] | 311 | [
"Computing stubs",
"Computer hardware stubs"
] |
76,111,276 | https://en.wikipedia.org/wiki/Xanthomonas%20campestris%20pv.%20raphani | Xanthomonas campestris pv. raphani is a gram-negative, obligate aerobic bacterium that like many other Xanthomonas spp. bacteria has been found associated with plants. This organism is closely related with Xanthomonas campestris pv. campestris, but causes a non-vascular leaf spot disease that is clearly distinct from black rot of brassicas.
Leaf spot diseases of brassicas were associated with X. campestris pv. armoraciae (McCulloch) Dye or X. campestris pv. raphani (White) Dye. The leaf spot isolates most commonly found in brassicas have been identified as X. campestris pv. raphani..
Hosts and symptoms
The host range of X. campestris pv. raphani is wider than X. campestris pv. campestris and includes Brassica spp., radish, ornamental crucifers like wallflowers and tomato.
Symptoms include circular dark spots that later became light brown or gray, sometimes surrounded by a water-soaked halo. In severely infections, the spots can coalesce and become irregular, but not limited by the veins. Symptoms also include black, sunken, elongated lesions on the middle vein, petiole, and/or stem.
Significance
This pathovar causes a minor disease in brassica crops; it can be occasionally isolated from seeds.
References
campestris pv. raphani
Bacterial plant pathogens and diseases
Pathovars | Xanthomonas campestris pv. raphani | [
"Biology"
] | 311 | [
"Bacteria stubs",
"Bacteria"
] |
76,111,290 | https://en.wikipedia.org/wiki/Linda%20J.%20Hayes | Linda J. Hayes ( Parrott) is a Canadian-born psychologist and distinguished international professor at the University of Nevada, Reno. She has contributed to the study and understanding of interbehaviorism and behavior theory and philosophy. Hayes has been honored for her contributions to behavior analytic research, teaching, and international development.
Early life and education
Hayes earned her doctorate in psychology at Western Michigan University after receiving a bachelor’s degree from University of Manitoba. She was a faculty member at West Virginia University and Saint Mary’s University before co-founding the behavior analysis program at University of Nevada Reno.
Research and career
Influenced by the work of J. R. Kantor, Hayes has translated Kantor’s philosophy of science and ideas for behavior analysts. Her research primarily focused on the behavior theory and philosophy areas of interbehaviorism and verbal behavior.
Hayes spent 32 years at the University of Nevada, Reno. The UNR behavior analysis program began as a self-capitalization model where faculty and students generated revenue to fund the program at almost no cost to the university. Hayes founded and directed UNR's satellite program, which brought behavior analysis training to parts of the US, Canada, Jordan, Taiwan, Saudi Arabia, China, and Kenya. She has received several international development and global engagement awards for her work with the satellite program. During her career at UNR, Hayes mentored 33 doctoral students.
Hayes served as president of the Association for Behavior Analysis International twice and held multiple terms on the executive council. On her retirement in 2022, Hayes was recognized with the distinguished faculty award from the University of Nevada, Reno.
Awards and honors
Fellow, Association for Behavior Analysis International
Fred S. Keller Award for Training of Behavior Analysis, American Psychological Association Division 25
Outstanding Teacher Award, College of Arts and Sciences at West Virginia University
Outstanding Faculty Award, Board of Regents of the Nevada System of Colleges and Universities
Outstanding Alumna Award, Western Michigan University
Distinguished Service to Behavior Analysis, Society for the Advancement of Behavior Analysis
International Development Award, Latin Association for Behavior Analysis and Modification
Global Engagement Award, University of Nevada, Reno
Select publications
Hayes, L. J. (2017). J. R. Kantor's contributions to psychology and philosophy: A guide to further study. The Behavior Analyst, 7, 169–181. https://doi.org/10.1007/BF03391900 PMID 22478609
Hayes, L. J. (1998). Remembering as a psychological event. Journal of Theoretical and Philosophical Psychology, 18(2), 135–143. https://doi.org/10.1037/h0091180
Hayes, L. J., & Fryling, M. J. (2023). Interbehaviorism: A comprehensive guide to the foundations of Kantor’s theory and its applications for modern behavior analysis. Context Press.
References
External links
Linda Hayes faculty page at the University of Nevada, Reno
Year of birth missing (living people)
Living people
21st-century American psychologists
University of Manitoba alumni
Western Michigan University alumni
University of Nevada, Reno faculty
West Virginia University faculty
Behaviourist psychologists | Linda J. Hayes | [
"Biology"
] | 644 | [
"Behaviourist psychologists",
"Behavior",
"Behaviorism"
] |
76,111,656 | https://en.wikipedia.org/wiki/Peripheral%20node%20addressin | Peripheral node addressin, often referred to as PNAd, are glycoprotein ligands. More formally, the term includes "lymph" to specify the node: peripheral lymph node addressin.
PNAd is a critical component of the immune system, enabling the targeted migration of lymphocytes to the lymph nodes and facilitating an effective immune response. PNAd's role in lymphocyte homing is essential for the proper functioning of the immune system, as it ensures that lymphocytes can efficiently enter the lymph nodes to encounter and respond to foreign antigens, such as viruses and bacteria.
PNAd is a type of cell adhesion molecule found on the surface of high endothelial venules (HEVs) in lymph nodes. It plays a crucial role in the immune system by facilitating the migration of lymphocytes, a type of white blood cell, from the bloodstream to the lymph nodes where they participate in immune responses.
The process of lymphocyte migration from the bloodstream to the lymph nodes is called lymphocyte homing. PNAd plays a key role in this process by interacting with L-selectin, which is present on the surface of lymphocytes. The adhesion molecule L-selectin binds to sulfated carbohydrate ligands on high endothelial venules (HEV). The binding between PNAd and L-selectin allows lymphocytes to slow down and roll along the inner surface of HEVs. This rolling action enables lymphocytes to come into close contact with other molecules called chemokines, which trigger the firm adhesion and subsequent transmigration of lymphocytes across the endothelial cells and into the lymph node.
References
Ligands
Immune system | Peripheral node addressin | [
"Chemistry",
"Biology"
] | 385 | [
"Ligands",
"Immune system",
"Biotechnology stubs",
"Coordination chemistry",
"Biochemistry stubs",
"Organ systems",
"Biochemistry"
] |
76,113,618 | https://en.wikipedia.org/wiki/Bioinspired%20armor | Bioinspired armor are materials that were inspired by the composition, and most importantly, the microstructures commonly found in nature’s natural defense mechanisms. These microstructures have been evolved by organisms to protect themselves from exterior forces, such as predatory attacks. These materials and their microstructures are optimized to withstand large forces. By taking inspiration from these materials we can design armor that has better penetration resistance and force dissipation properties than previously possible.
Nature uses abundantly available materials to develop structures that have the most efficiently aimed mechanical properties. By examining the microstructures produced in nature, scientists can engineer these structures with more optimal materials to produce the most mechanically robust version of these structures. Biological/Bioinspired armor is specifically aimed at producing protective materials by optimizing naturally occurring defensive materials.
This article will cover common types of defensive materials observed in nature, how these microstructures contribute to the impressive material properties, and how scientists have used this knowledge to develop novel protective materials.
Function and microstructure
Armor for High-Velocity Collision Protection
Nacre
Nacre is the composite biological material that makes up the shell of mollusks, featuring high strength and toughness. Layers of nacre work together to protect soft-bodied organisms from external loads, mainly including predatory attack and underwater currents, and can thus dissipate a large amount of energy during impact.
The hierarchical structure of nacre has been observed on many length scales, from the microscale to the nanoscale. On the microscale, the structure of nacre is akin to “brick and mortar”: composed of long, thin brittle plates in a polygonal shape held together by a soft and flexible polymer. The mineral tiles are composed of aragonite, a polymorph of calcium carbonate, and are held together with a polymer of chitin and asparagine- rich protein. The aragonite tiles are 0.5 um thick, while the biopolymer layer is 50 nm. The arrangement of these tiles affects the mechanical properties of the nacre. Columnar nacre occurs when the tablets stack, creating regions of aragonite platelet overlap. Sheet nacre occurs when the tablets are arranged randomly between adjacent layers. Other features on the nanoscale, such as mineral bridges and asperities contribute to the high fracture resistance of nacre.
Nacre has been studied for potential applications in human armor. Engineered nacre-like composites have been shown to possess improved ballistic-penetration resistance compared to monolithic armor of the same area and density.
Turtle Shells
A turtle shell is a bio-composite consisting of a keratin-coated dorsal shell, or carapace, and a flat interior made of cancellous bone sandwiched between thin layers of cortical bone. The flat, bony configuration allows for significant weight reduction, thereby resulting in higher stiffness, strength, and toughness-to-weight ratios. This design renders the shell particularly effective against sharp, high-strain assaults, providing vital protection from predators such as alligators, jaguars, and birds.
Soft collagenous tissue that joins adjacent interdigitating bone plates, called sutures or interdigitating sutures, allows a turtle to respond to a variety of different loading regimes. Turtle shells were considered to be biological polymers before synthetic polymers were developed, and were thus one of the first natural analogs of early man-made armor.
Armor for Low-Velocity Blunt Impact Loading
A key application for biological-inspired armor is protection against low-velocity blunt-impact loading. Blunt impact loading refers to the direct contact of a blunt object on a body, resulting in physical force or trauma. It involves the transfer of kinetic energy, without penetration, and usually can result in compression, deformation or material fracture. Common examples would include sports injuries (impacts that result in concussions), assaults (punches, kicks), or falls. Many instances in nature provide organisms with an ability to sustain these loads, and hence provide models for biomimetic armors.
Hooves
Bovine and equine hooves are highly studied examples of blunt impact loading and shock absorption in nature. This is primarily because the hooves act as a natural energy absorber for animals such as horses and cattle with high force and velocity gait patterns.
Structure
Both bovine and equine hooves are made of the protein α-Keratin. α-Keratin is a structural, fibrous protein, the same one found in our hair and nails. The keratin molecules are held together by H-bonding and disulfide cross-linked bonds, which enhance the rigidity of the protein. α-Keratin chains twist together to form coiled-coil dimers. Coiled dimers bind with other coiled dimers to produce photo filaments, which further bind to form a photo fibril, then eventually an intermediate filament (IF). Within the outer wall of the hoof, are tubule structures oriented parallel to the leg (220x140 um, 50 um medullary cavity). Keratin intermediate filaments are organized as circular lamellae that surround these tubules.
Properties
Many of the mechanical properties associated with hooves are due to the presence of tubules. The layers of tubules with their lamellar keratin surroundings provide excellent crack deflection and fracture toughness. When a crack is introduced into a material, it will continue to propagate until it hits a new interface. Hooves have layers of keratin IFs surrounding each tubule, each in slightly changing orientations, creating multiple interfaces that the crack will “bump” into, and thus makes the hoof a highly fracture-resistant material. The high fiber alignment and density of keratin as well as the longitudinal orientation of the tubules helps with energy absorption from blunt loading. Finally, the intratubular matrix within the tubules of the hooves is less stiff and dense than that surrounding it, reducing the weight of the hoof. All these properties help hooves support large compressive and impact loads while providing shock absorption from the impact, and make for promising impact loading models.
Horns
Horns, such as those found in goats, buffalo, and rhinoceroses are another keratin based structure that may provide inspiration for biological armor. Given that horns serve as a defense mechanism for these animals, these structures are well able to withstand significant impacts.
Structure
Horn has a very similar structure to hoof, as they are both composed of α-Keratin. The structural makeup of these types of horns involves a lamellar keratin structure, with microtubules radially oriented. These tubules are much larger than those found in hooves, with exact dimensions depending on the species, but are also surrounded by keratin IF lamella. This gives the horns an ability to maintain stiffness in tension while still dissipating kinetic energy from compressive forces and impact.
Properties
Given the extremely similar structure of horns to hooves, they share many similar properties. One such property is crack deflection and fracture toughness. Again, the layered lamellar hierarchy of keratin surrounding the tubules creates many interfaces for cracks to run into. One study found that the critical crack length for horn was 60%, meaning that a crack would have to extend through 60% of the transverse direction of a horn before it became critical, which shows extremely high toughness. Horn also has extremely high energy absorption and ability to withstand stress. This is attributed to the tubule orientation and keratin fiber density; unique to certain animals, the spiral geometry of the horn also allows for higher energy absorption. Specifically to bighorn sheep, studies found that their horns had a compressive stress of 4.0 MPa, a tensile stress of 1.4 MPa, and a fighting force of 3400N. The compressive stress is obviously much larger than the tensile stress, but like many other anisotropic materials, this is because an animal such as the bighorn sheep who uses their horns for fighting will be more likely to experience compressive stress and blunt impacts rather than tension. Finally, similar to hooves, horns are extremely tough but also lightweight, due to the lighter, less dense intratubular matrix.
Crustaceans
Aside from nacre and conch, crustacean exoskeleton and cortical bone are other biological structures that possess intricate features that may be beneficial for ballistic protection and low velocity blunt impact.
Structure
The exoskeleton of crustaceans such as crab is made of chitin, which is an amino polysaccharide polymer. A polysaccharide polymer is derived from an amino sugar, a type of sugar where the hydroxyl group is replaced with an amine group. The chitin fibers are embedded in a calcite matrix. The crustacean exoskeleton, like many of the other models discussed previously, is hierarchical. It starts with the chitin polymer fibers arranged in a honeycomb pattern. These “honeycomb” planes are then stacked in a Bouligand pattern, consisting of several layered, rotating planes. This makes up the inner, endocuticle layer of the crustacean exoskeleton and accounts for 90% of the total exoskeleton. The outer exocuticle layer contains more densely packed chitin layers that end up being 200 μm thick. Thickness of the exocuticle and endocuticle layers vary in different parts of crustaceans.
Properties
One major mechanical property of the crustacean exoskeleton is high toughness and stiffness. This is attributed to the thick, densely layered exocuticle layer. Energy Dispersive X-Ray mapping found that the exocuticle layer has higher calcite mineralization in its matrix, increasing the “hardness” of the material. The endocuticle layer of the exoskeleton is responsible for energy absorption and crack deflection properties. This layer has a much lower stacking density of the chitin polymer layers than the exocuticle layer. This means that when placed under compressive forces, it is able to dissipate the load. Like mentioned in hoof and horn, the Bouligand pattern provides several interfaces for cracks to run into, creating high crack deflection. Overall, the combination of the hard, stiff exocuticle and the energy absorbing, compressible endocuticle create a structure that is extremely difficult to penetrate and serve as a good model for both blunt impact and ballistic shock applications.
Conch Shell
Structure
Conch is a type of shell composed of calcium carbonate composite material that has a three-order lamellar structure. The first order contains ceramic plates that are 5-60 μm thick. The second order consists of ceramic beams at two different 45º orientations, about 5-30 μm thick, and the third order is made up of thousands of tiny ceramic planks, 75-100 nm thick.
Properties
The lamellar layers that make up the conch shell provide strong crack propagation. This structure also gives the conch shell several modes of fracture, which act as toughening mechanisms when put under different loads. Mode 1 fracture, which involves loading orthogonal to the plane of the crack, exists in the third order lamellae due to delamination of the layers. Mode 2 fracture, which involves loading parallel to the plane of the crack, also exist between third order lamella and cause a buckling effect. Compressive and bending tests showed that conch shell was highly anisotropic. It was found that conch is about 60MPa stronger in parallel loading compared to perpendicular loading. This was validated through a Weibull analysis for dynamic compression in surfaces both parallel and perpendicular to the load, the parallel loading was found to fail at higher fracture stresses.
Armor for Sharp Impact Loading
Crocodiles and Alligators
Crocodilian skin has the potential to be used as armor for sharp impact loading because its skin is embedded with bony particles (scutes) (i.e., osteoderms) . Dubbed “armored skin”, osteoderms are composed of hydroxyapatite and collagen, the same components found in bone. The scutes have a bony network on their surface and are connected with the collagen fibrils. Osteoderms are present in reptiles (e.g., lizards, crocodilia, dinosaurs), fish, and some mammals (e.g., armadillos, mice), for protection from predators. The scutes on crocodiles have multiple functions, like thermoregulation, calcium storage, and toughening. The low weight and flexibility of the scutes are attributed to their porosity (~12%), while the matrix surrounding the pores gives them their hardness. Compression tests indicate that crocodilian scutes are strongest in the axial direction, with a strength of 67 MPa. The toughness of the scutes can be attributed to pore flattening, mineral bridge formation, and collagen bridge growth as energy dissipation mechanisms upon impact loading.
Crocodiles also have highly irregular polygons of keratinized skin on their head and faces, which offers additional protection. The cracks on the head and face of the crocodilian skin are generated from a cracking response, i.e., “crocodile cracking” that occurs when stress is applied. This cracking mechanism releases deformation energy and helps the skin maintain its hard exterior, with increased flexibility.
Armor for Mobility and Movement
In nature an efficient biological armor needs to be able to protect the organism while introducing the least amount of hindrance on its function. For many organisms' movement is one of their most important abilities, therefore, the armor cannot limit their movement mechanics.
Unlike the continuous structure used to protect stationary organisms, like clam shells, these types of armor are usually composed of many separate structures to allow for the elongation and contraction required for movement, while maintaining complete protection. There are two major classes of biological armor found in nature, these are scale armors and osteoderm armor. Both of these biological armors have specialized microstructures and macrostructures that produce the impressive properties of these materials.
Scales
Scale armor is the most widely expressed armor in nature. It is mostly seen on aquatic animals; however, it is also seen on some land animals such as pangolins. This armor is known for its impressive flexibility, while also its impressive compressive and puncture resistance. There are many subcategories of fish scales, but the main three are Elasmoid, Ganoid, and Placoid. These scale types are distinguished by their mechanical properties, geometric shape, and macroscopic alignments. Elasmoids are the typical oval shaped scales found on ray-finned fish. These scales are known for their ultra lightweight, puncture resistant, and flexibility which allows for the propulsion movements required for swimming. Ganoid scales are rhomboid in shape and exhibit enhanced stiffness, which is due to their thicker layer of mineralized material. Lastly, Placoid scales are best known by their shape. They have spines that run against the pattern of the scale which results in a sharp or rough feeling to the touch. These scales are found on animals like sharks and stingrays.
Structure
Elasmoid scale strength against force loading are significant due to their macrostructure. The macrostructure is composed of their positioning, shape, and scale features. Elasmoid scales are oval in shape, three quarters of which is covered by neighboring scales. This overlapping does not only allow for the movement of the organism while maintaining complete coverage, but also aids in the compressive force resistance. When the scales are loaded with a compressive force, it is distributed across all the neighboring scales. As these scales are bent into each other, in compressive loading or in natural movement, the scales exhibit a material hardening effect. This allows for each scale to be produced below the required stiffness to protect against an attack, however when joined together in an overlapping pattern, the material is able to resist large compressive forces. This is one structure that this armor design uses to maintain light weight.
Another major macroscale system of the elasmoid scales are the physical scale features. The scales have grooves running from the focal point of the scale towards the edge, known as radii, as well as rings around the focal point in a concentric pattern, known as circuli. Both the radii and circuli are hypothesized to help in the bending mechanisms of the scale as well as aid in anchoring the scale into the dermis.
The macroscale structures of the scales are largely important for the armors function; however, the microstructures give the materials their impressive properties. These scales are made from composite materials. These are mineralized protein matrices that allow for the strength and toughness of the mineral while reducing the brittle effects of these materials with protein components. In the elasmoid scale there are three main layers. The Limiting layer, which is the outermost layer; the elasmodine outer, and the elasmodine inner layers which are defined by their level of mineralization.
The limiting layer is found just on the surface of the scale where it is the first line of defense against puncture. This layer varies its thickness depending where it is located on the scale as well as which species scale it is. It is typically on the 10-1000 micrometer scale in thickness. The limiting layer also forms various shapes depending on if it is posterior or anterior on the scale. Posterior limiting layer commonly forms varying pillar structures assumed to be for varying water interface functions, while the anterior portion is most commonly formed into the circuli shape discussed earlier. The cross-section of the anterior region shows a saw tooth shape. This is assumed to help with dermal integration.
This composite material is almost completely mineral apatite with small amounts of collagen. Between varying fish species researchers noted a carbonate substitution in the apatite structure. This material's structure is well developed for its application. This layer of the scales needs to be tough and stiff to help defend from punctures which explains the high level of mineral in this layer. The apatite percent volume in the limiting layer was around 65%.
Below the limiting layer there is a thicker basal plate composed of larger collagen fibrils, called the elasmodine layer. The elasmodine layer is split into the external elasmodine and internal elasmodine which are distinguished by the difference in their mineral content within the composite material. The external layer contains higher concentration of the mineral component while the internal layer contains almost only collagen. This variation between slightly mineralized to almost completely unmineralized composite leads to the great flexibility of the scales. As a force is applied to the surface of the scale, as seen in predatory attack, the outermost layer is put under compressive force and needs to resist puncture, while the innermost layer is experiencing tensile forces. The high mineral concentration of the limiting layer and the external elasmodine are better suited for dealing with compressive forces, while the almost completely unmineralized material of the inner elasmodine is better suited for stretching forces. The outer elamsodine layer is around 35% mineralized.
The collagen fibril alignment in the composite material plays a large role in the material properties. These collagen fibrils form a structure known as the Bouligand structure. The Bouligand structure is a rotated plywood design that imparts multidirectional strength. The collagen fibers in one layer are all aligned linearly in a single direction to give strengthening in that one direction. These unidirectional collagen fibril plies are then slightly offset from their neighboring layers to help with the materials overall multidirectional strength. The scale’s strength and elastic modulus correlates to the number of elasmodine layers and the thickness of those layers compared to the overall scale thickness. Additionally, the collagen fibrils within each lamella layer do not demonstrate grouping. Each fibril is isolated and connected to its neighbors through sacrificial bonds. This connection allows for another level of force dissipation as the sacrificial bonds will break first under force instead of the macroscale material.
The structure of the scale armor is specifically designed to provide protection during movement, dissipate forces, and maintain lightweight. This is then combined with the microstructures of the scale to produce a material that is best suited for the required parameters. The composite material provides force resistance and puncture resistance, while still providing the flexibility required for the macrostructure movements. This combination of aspects provides great protective armor for many animals on earth.
An example of this armor structure in nature are the Arapaimas fish. These are large fish that exhibit these elasmoid scales and heavily rely on their microstructure and macrostructures to protect them. These fish live in the same water as piranhas, so having effective armor to protect themselves from possible piranha attacks are vital to their survival. The overlapping of the scales allows for the armor to absorb kinetic energy by transmitting the impact energy to adjacent discs. A larger number of scale layers can protect from larger forced attacks. For example, the Arapaima have an average of three scale layers which is capable of protecting from piranha attack. Without this efficiently designed armor these fish would not be protected in their habitats.
Osteoderms
Osteoderms are bony deposits formed inside the dermis, commonly found in lizard species and alligators. Osteoderms form inside the dermis with or without skeletal connection. The level of osteoderm distribution varies heavily between species. Some animals are completely covered, while others only have the armor in certain areas of the body.
Additionally, the size of the osteoderms varies highly depending on species and area of the body. There are typically larger plates on the back, side and belly, then smaller plates around the head and tail. There are also many types of osteoderm structures. They can form in isolated groups creating a partial coverage of the organism, but they can also form a structure more similar to the fish scales, where they overlap each other to form a more complete armor. Depending on the macroscale structure of armor the osteoderm morphology changes. The overlapping layers are typically thinner than standalone plates seen in the isolated groups.
Osteoderms are made of mineral composite materials. They include various types of bone, mineralized and unmineralized collagen bundles, as well as blood vessels. The composite material that makes up osteoderms are made from calcium phosphate and collagen. Due to the bone-like material structure, these materials are much more stiff than the fish scales previously discussed. With a complete coating of this armor, it would inhibit the mobility of the organism. However, these structures are connected by stiff fibers and dermal tissue which allow for the movement of the osteoderms. The soft regions, however, are not protected by the armor.
Osteoderm structures are formed similarly to bone; the outer layer is made of parallel fibered bone, with a cancellous core lined with lamellar bone. These bone structures have very similar mechanical properties to skeletal bone. By producing this dermal layer of bone, the organism creates a sacrificial layer of stiff bone at the surface of the skin to defend against point force attack. This structure is then surrounded by flexible dermal material to allow for movement, however as stated before, the gaps between the osteoderms are not protected leaving some vulnerable areas. This armor combines larger and more mechanically robust materials in a macrostructure design that still allows for movement.
Implications
Military
Given their combined lightweight and protective nature, nacre, conch shell and fish scales are a few of the many organisms being studied by US military departments for bioinspired armor applications. The major complication that must be improved for these types of armor is enhancing flexibility and reducing weight of armor without compromising protection from ballistic type impacts.
The primary benefit from nacre-inspired biological armor is its extreme ability to resist penetration through energy dissipation. This is especially prevalent when compared to monolithic ceramic panels. Additionally, conch inspired materials provide improved tortuosity when compared to monolithic plates. Biological materials derived from these structures show promise for lightweight armor systems without compromising impact resistance. Materials inspired from fish scales have the potential to provide bending and rotation abilities to wearable armor systems as well.
Bone inspired bio-armor systems are also being explored for ballistic shock mitigation applications. One such system developed by the US Army Research Laboratory utilizes an alternating soft and stiff material distribution as found in the bones located in the forelimbs of horses. This particular bone system not only provides exceptional load bearing and impact resistance abilities, but has a design replicable for alternative armor applications. Using metallic foam materials, a “coupon” panel was designed to mimic the mechanical properties of the bone systems, and placed on a cylindrical steel support. The system was tested using gas gun testing, in which a high speed projectile was shot at the coupon. An Alulight aluminum foam (which is the same material consisting of the soft layers of the coupon) at different densities were used as a baseline for comparison. It was found that the bone and hoof inspired system was not only lighter, but had less projectile penetrations and shock absorption. The bone system had significantly reduced the accelerations of peak stress waves over both high and low frequencies, showing enhanced shock absorption.
Sports helmets and Equipment
Bioinspired armor also presents several applications in athletic equipment including helmets and other protective gear.
The alligator gar fish has scales resistant to cuts and punctures. Using 3D printing technology, various sized scales can be added to rubber pads providing these properties to regular clothing. This was tested on Kevlar gloves in particular, with smaller scales around finger joints and larger scales around the base of the hand. This was found to be useful in protecting against stab wounds or other sharp objects.
Polymer materials inspired by conch shells have also been explored, as they are difficult to break in drop tests, simulating the same impact as a bullet wound. A conch inspired design could also have the potential to make helmets thinner and lighter while offering the same level of protection. For example, a research group at MIT developed a 3D printed conch inspired prototype for use in helmets and body armor. This prototype was fabricated using proprietary Stralasys photopolymers Veromagenta and Tangoblackplus, which were deposited and cured under UV light. Using 3D printing and additive manufacturing techniques, the research group arranged the layers with 2 orders of hierarchy, and mimicked the alternating plank angles seen in conch. Drop tower testing was conducted where the composites were dropped at different heights, reaching up to 3 m/s. A composite with only a single order of hierarchy was used for comparison. The prototype with 2 orders of hierarchy was able to withstand damage at all incident velocities, while the control was damaged at a velocity of 2.5 m/s. This composite was found to enhance impact performance by 70% compared to the single order prototype, and 85% compared to a stiff material control. This study confirmed that hierarchical designs inspired from conch shell may have impressive applications in helmets due to their extraordinary ability to withstand blunt impacts.
Dragon silk is a type of spider silk that is thinner than human hair, yet stronger than Kevlar. Utilizing this material would create protective gear that is light, breathable, biodegradable and durable, with potential applications in bullet proof vests.
Other Applications
Overview
In addition to creating armor for protection, bio-inspired armor also has medicinal implications. For instance, sponges, sealants, and powders can simulate blood coagulation and provide a barrier to an injury site. In particular, phenol-amine crosslinking found in insect exoskeletons has anti-cellular adhesion, antithrombotic, and antifouling properties. Combining the properties of the sponges and insect skeleton with the bioinspired materials mentioned above could lead to the creation of hybrid bioinspired armor with antimicrobial, antithrombotic properties and toughness.
Insect Sclerotization-Inspired Technologies
The process of insect sclerotization involves the hardening of the exoskeleton shell which is facilitated by the covalent crosslinking of dopamine derivatives with chitin fibers and other endogenous proteins to generate the chitinous exoskeleton. One research group was able to create a crosslinked version of Bovine Serum Albumin (BSA) and Hydro caffeic acid (HCA) grafted with polyethylene glycol (PEG), by using the same mechanism found in insect sclerotization. The new cross-linked molecule had antifouling properties and prevented the formation of biofilms on biomedical devices, helping maintain sterility.
Using the same crosslinking method, catechol and collagen were crosslinked and chelated with zinc ions to create a “metal-phenol-polyamine system” on the surface of a sponge. The presence of the metal ions gave the sponge antimicrobial properties against gram-negative and gram-positive bacteria. The cross-linked substrates activated coagulation pathways to promote platelet aggregation, allowing the sponge armor to have hemostatic and would-healing properties. The efficacy of this technology was modeled in rabbit and rat studies, which demonstrated successful hemostasis and wound healing when these animals were treated with these sponges.
Medicinal Applications
Investigating the mechanisms behind the formation of biological armor can also provide insights into human disorders and diseases. In particular, the development of the osteoderms in alligator skin can be used to investigate the disease progression of heterotrophic ossification. Heterotrophic ossification, also known as “Stone Man” disease, is a human disease that results in bone formation in mature soft tissues. While the causes of heterotrophic ossification are known, the cellular mechanism has remained elusive. Alligator scutes have the potential to be a useful disease model for heterotrophic ossification because the osteoderms in alligators form in soft tissues at a late stage in development (post-embryonic stage), similar to the bone formations in heterotrophic ossification. Using the alligator osteoderms to study heterotrophic ossification's mechanism and disease progression can potentially lead to more effective treatment options for the disease (e.g., pharmaceutical).
Researchers at the Naval Medical Research Institute in Shanghai investigated the healing properties of shark skin on wounds exposed to seawater. Because wounds immersed in seawater are exposed to low temperatures, high salt concentrations, and various microbes they tend to have a slower healing process. Collagen (type I) extracted from Blue sharks and an anti-seawater immersion Polyurethane film was deposited on a sponge to create a shark skin collagen sponge bandage. The shark skin bandage shielded the wound from seawater for up to four hours after submersion and strongly promoted wound healing, compared to the gauze and chitosan bandages treated with Polyurethane film. Shark skin has also been investigated for applications in the transportation industry as a coating for airplanes to reduce drag.
Manufacturing Processes
Additive Manufacturing
Additive manufacturing methods, including 3D printing/fused deposition modeling, material jetting, and powder based fusion have been used to manufacture bio-inspired armor.
3D printing and fused deposition modeling of biomimetic armor is popular due to its cost effectiveness and ease of manufacturing. The filament-based 3D printing process involves extruding a polymer filament through a nozzle and printing objects layer-by-layer onto a hot surface. Common filaments used in this process are ABS, PLA, TPU, and PE. Once finished, the part requires no additional treatment. Powder-based 3D printing involves spreading a thin layer of powder onto a surface and connecting it with a binder into the desired geometry. Undesired powder is removed once the object is printed. Some common powders used are Sr-HT, aluminum oxide powder, and calcium polyphosphate. Compared to filament-based 3D printing, powder-based manufacturing provides higher manufacturing accuracy and finer detail on the micro scale. Overall, challenges with 3D printing include recreating the precise details on the nanoscale, poor surface quality, and slow printing rate.
3D printing and FDM have been used to create armors mimicking the structure of nacre, conch, and fish scale. In biomimetic nacre-like armors created through FDM show improved impact resistance compared to a monolithic panel, as well as minimized damage. For overlapping scales based on fish, 3D printing allowed flexibility while maintaining a multiple layer defense. Stiff and soft layered extruded armor based on horse hooves also allowed for greater energy absorption relative to a monolayer.
Material jetting (MJ), also referred to as 3D inkjet printing, is the process by which a photopolymer resin is deposited onto a surface as droplets, then cured by UV light. MJ features high resolution, desirable surface properties, and multi-material prints. MJ has been used to create composite stiff/soft biomimetic materials, as well as common structural motifs like Bouligand, helicoidal, overlapping, and lamellar. MJ is therefore useful for printing conch shell inspired (cross-lamellar), fish scale inspired, and chitinous inspired armors. Despite these benefits, MJ is expensive, requires post-processing, and uses sensitive materials that may degrade the final quality of the part.
Subtractive Manufacturing
Subtractive manufacturing methods have been used in the production of biomimetic armor, although they are not as common as additive manufacturing methods in this field. Biomimetic armor often takes inspiration from natural structures and organisms to create materials with enhanced properties such as strength, flexibility, and lightweight characteristics. Some subtractive manufacturing methods that have been employed in the fabrication of biomimetic armor include CNC machining, and laser cutting/engraving.
Computer Numerical Control (CNC) machining involves the use of computer-controlled machinery to remove material from a workpiece. It allows for precise shaping and detailing of various materials, including metals, ceramics, and composites, which can be utilized in biomimetic armor production. CNC machining has been used to create nacre-like dovetail tablets using PMMA.
Laser cutting/engraving involves the use of a high-powered laser beam to cut through materials. It offers high precision and can be used with a variety of materials, including metals, polymers, and composites. Laser cutting can be employed in the fabrication of biomimetic armor to create intricate designs and patterns, and has notably been used to engrave the dovetail patterns of nacre tablets onto carbon-fiber/epoxy composites. Additionally, laser engraving has been used to manufacture a segmented plate inspired by fish scales that was then placed on a soft elastomeric substrate.
These subtractive manufacturing methods can be combined with other techniques and processes to create biomimetic armor that mimics the structural and functional characteristics of natural organisms, providing enhanced protection and performance in various applications.
References
Bioinspiration
Armour | Bioinspired armor | [
"Engineering",
"Biology"
] | 7,369 | [
"Biological engineering",
"Bioinspiration"
] |
76,113,713 | https://en.wikipedia.org/wiki/Seiler%20oscillator | The Seiler oscillator is an LC electronic oscillator. It was presented in 1941 by E. O. Seiler. The original implementation used a vacuum tube in an Electron-coupled oscillator circuit. Like the Clapp oscillator and the Vackář oscillator it is a variation of the Colpitts oscillator. It uses a voltage divider made of two capacitors, named C3 and C4 in the original schematic. The tuning capacitor C1 is parallel to the inductance L1 of the LC circuit. In an Clapp oscillator, the tuning capacitor is in series to the inductance. The variable capacitor C2 controls the coupling between the tube and tank (LC circuit).
Practical example
The schematic shows an example with component values. The Seiler oscillator uses a LC circuit L1, C1 that is connected via C2 to a capacitive voltage divider C3, C4 that connects to the amplifier Q1. C1 and C2 are calculated for inductance L1 having a unloaded Q factor of 250. Resistor R1 sets the collector current to 0.5mA with no oscillation. The negative supply voltage V2 allows direct connection from Q1 base to ground. The radio frequency choke L3 is needed to isolate the LC circuit from the power supply, but has a potential problem. L3, C3 and C4 create a Colpitts oscillator circuit. R2 reduces the Q factor of L3 and prevents oscillation on the wrong frequency. The correct oscillator frequency is 10MHz. The load resistor RL is part of the simulation, not part of the circuit.
References
Sources
Electronic oscillators
Electronic design | Seiler oscillator | [
"Engineering"
] | 382 | [
"Electronic design",
"Electronic engineering",
"Design"
] |
76,113,735 | https://en.wikipedia.org/wiki/Phyllotopsis%20salmonea | Phyllotopsis salmonea is a species of fungus in the family Phyllotopsidaceae.
Habitat and distribution
Phyllotopsis salmonea is found in South Africa and Burundi.
References
Fungi described in 1975
Fungi of Africa
Inedible fungi
Fungus species
Agaricales | Phyllotopsis salmonea | [
"Biology"
] | 58 | [
"Fungi",
"Fungus species"
] |
76,113,784 | https://en.wikipedia.org/wiki/Phyllotopsis%20subnidulans | Phyllotopsis subnidulans is a species of fungus in the family Phyllotopsidaceae.
References
Fungi described in 1936
Inedible fungi
Fungus species
Agaricales | Phyllotopsis subnidulans | [
"Biology"
] | 41 | [
"Fungi",
"Fungus species"
] |
76,113,899 | https://en.wikipedia.org/wiki/Pachycudonia%20spathulata | Pachycudonia spathulata, commonly known as Manzanita butter clumps, is a rare and little-known fungus that grows in association with manzanita and Pacific madrone trees on the west coast of North America. This fungus was first described in 1942 by Sanshi Imai as Cudonia spathulata and renamed by Imai in 1950 to Pachycudonia spathulata.
Mycologists are investigating the range of this fungus and seeking new observations and specimen collections.
Notes
References
Helotiales
Fungi of North America
Fungi described in 1942
Taxa named by Sanshi Imai
Fungus species | Pachycudonia spathulata | [
"Biology"
] | 129 | [
"Fungi",
"Fungus species"
] |
76,114,596 | https://en.wikipedia.org/wiki/MS-377 | MS-377 is a selective antagonist of the sigma-1 receptor. It possesses anti-psychotic properties.
Properties
MS-377 acts selectively at the sigma-1 receptor as an antagonist. It does not act on dopamine or serotonin receptors unlike most anti-psychotics. Tests have shown that MS-377 could displace ligand binding from the sigma-1 receptor, but did this not happen at the sigma-2, 5-HT2 and D2 receptors, suggesting that it is selective for the sigma-1 receptor.
Despite not acting at serotonin and dopamine receptors, it still affects those monoamine systems. It has been shown that MS-377 reduced the release of serotonin and dopamine induced by PCP. It has also been shown to decrease methamphetamine behavioral sensitization, this is also observed with other sigma antagonists.
References
Receptor antagonists
Sigma receptor ligands
Pyrrolidones
Piperazines
4-Chlorophenyl compounds
Methoxy compounds
Ethanolamines | MS-377 | [
"Chemistry"
] | 220 | [
"Neurochemistry",
"Receptor antagonists"
] |
76,114,836 | https://en.wikipedia.org/wiki/Exidia%20purpureocinerea | Exidia purpureocinerea is a species of fungus in the family Auriculariaceae. Basidiocarps (fruit bodies) are gelatinous, densely covered in small spines, purple-grey, and cushioned-shaped at first, becoming effused. The species occurs in southern Africa on dead wood.
Taxonomy
The species was originally described from Boschberg (in the Sneeuberge) in 1882 by Yorkshire-born, South African botanist and mycologist Peter MacOwan.
Description
Exidia purpureocinerea forms purple-grey, gelatinous fruit bodies that are cushion-shaped at first, later coalescing to become irregularly effused. The surface is densely covered in small spines. The spore print is white.
Microscopic characters
The microscopic characters are typical of the genus Exidia. The basidia are ellipsoid, septate, 14 to 18 by 10.5 to 12 μm. The spores are weakly allantoid (sausage-shaped), 14 to 18 by 4.5 to 5.5 μm.
Similar species
The original description notes that Exidia purpureocinerea is similar to E. glandulosa, but differs in its colour and denser smaller papillae (spines). The densely spiny, coalescing fruit bodies are typical of the genus Tremellochaete and the South African species resembles the New Zealand species Tremellochaete novozealandica.
Habitat and distribution
Exidia purpureocinerea is a wood-rotting species. It is currently only known from South Africa.
References
Auriculariales
Fungi described in 1882
Fungi of Africa
Fungus species | Exidia purpureocinerea | [
"Biology"
] | 349 | [
"Fungi",
"Fungus species"
] |
76,115,003 | https://en.wikipedia.org/wiki/Tina%20Nenoff | Tina M. Nenoff (born 1965) is an American materials scientist and chemical engineer who works as a senior scientist and Sandia Fellow at Sandia National Laboratories, on leave from Sandia for a two-year term as deputy and science advisor to Jill Hruby, the Under Secretary of Energy for Nuclear Security. Her research concerns nanoporous materials such as zeolites and metal–organic frameworks, and their applications including reverse osmosis, water splitting for the hydrogen economy, and the detection and sequestration of radioactive iodine produced as nuclear waste. She also developed use of crystalline silicotitanates (discovered by Anthony and Dosch) to remove radioactive cesium from contaminated seawater after the Fukushima nuclear accident.
Education and career
Nenoff was born on December 7, 1965, in Orange, New Jersey, the daughter of a biologist and a physician. After attending an all-girls high school, she majored in chemistry at the University of Pennsylvania, graduating in 1987. Originally intending to go into medicine, she shifted direction under the mentorship of Alan MacDiarmid. Instead, after a year and half working at Ciba-Geigy, she returned to graduate study. She earned a PhD in chemistry from the University of California, Santa Barbara in 1993, supervised by Galen D. Stucky, and has worked at Sandia since then.
Recognition
Nenoff was elected as a Fellow of the American Chemical Society in 2011 and as a Fellow of the American Association for the Advancement of Science in 2019. The Society of Women Engineers gave her an achievement award in 2022 "for groundbreaking research in nanoporous materials; and for instilling in others the ethics and integrity for guiding future discoveries in chemistry and chemical engineering". She was elected to the National Academy of Engineering in 2024, "for translating fundamental understanding of nanoporous materials into applications with societal and national security impact".
References
External links
1965 births
Living people
People from Orange, New Jersey
American chemical engineers
American materials scientists
American women engineers
Women chemical engineers
Women materials scientists and engineers
University of Pennsylvania alumni
University of California, Santa Barbara alumni
Fellows of the American Chemical Society
Fellows of the American Association for the Advancement of Science
Members of the United States National Academy of Engineering | Tina Nenoff | [
"Materials_science",
"Technology"
] | 460 | [
"Women materials scientists and engineers",
"Materials scientists and engineers",
"Women in science and technology"
] |
76,115,030 | https://en.wikipedia.org/wiki/Feigenbaum%27s%20First%20Constant | The first Feigenbaum constant is the limiting ratio of each bifurcation interval to the next between every period doubling, of a one-parameter map
where is a function parameterized by the bifurcation parameter .
It is given by the limit
where are discrete values of at the th period doubling.
Names
Feigenbaum constant
Feigenbaum bifurcation velocity
delta
Value
30 decimal places : =
A simple rational approximation is: , which is correct to 5 significant values (when rounding). For more precision use , which is correct to 7 significant values.
Is approximately equal to , with an error of 0.0047%
Illustration
Non-linear maps
To see how this number arises, consider the real one-parameter map
Here is the bifurcation parameter, is the variable. The values of for which the period doubles (e.g. the largest value for with no period-2 orbit, or the largest with no period-4 orbit), are , etc. These are tabulated below:
{| class="wikitable"
|-
!
! Period
! Bifurcation parameter ()
! Ratio
|-
| 1
|| 2
|| 0.75
|| —
|-
| 2
|| 4
|| 1.25
|| —
|-
| 3
|| 8
||
|| 4.2337
|-
| 4
|| 16
||
|| 4.5515
|-
| 5
|| 32
||
|| 4.6458
|-
| 6
|| 64
||
|| 4.6639
|-
| 7
|| 128
||
|| 4.6682
|-
| 8
|| 256
||
|| 4.6689
|-
|}
The ratio in the last column converges to the first Feigenbaum constant. The same number arises for the logistic map
with real parameter and variable . Tabulating the bifurcation values again:
{| class="wikitable"
|-
!
! Period
! Bifurcation parameter ()
! Ratio
|-
| 1
|| 2
|| 3
|| —
|-
| 2
|| 4
||
|| —
|-
| 3
|| 8
||
|| 4.7514
|-
| 4
|| 16
||
|| 4.6562
|-
| 5
|| 32
||
|| 4.6683
|-
| 6
|| 64
||
|| 4.6686
|-
| 7
|| 128
||
|| 4.6680
|-
| 8
|| 256
||
|| 4.6768
|-
|}
Fractals
In the case of the Mandelbrot set for complex quadratic polynomial
the Feigenbaum constant is the limiting ratio between the diameters of successive circles on the real axis in the complex plane (see animation on the right).
{| class="wikitable"
|-
!
! Period =
! Bifurcation parameter ()
! Ratio
|-
| 1
|| 2
||
|| —
|-
| 2
|| 4
||
|| —
|-
| 3
|| 8
||
|| 4.2337
|-
| 4
|| 16
||
|| 4.5515
|-
| 5
|| 32
||
|| 4.6459
|-
| 6
|| 64
||
|| 4.6639
|-
| 7
|| 128
||
|| 4.6668
|-
| 8
|| 256
||
|| 4.6740
|-
|9
||512
||
||4.6596
|-
|10
||1024
||
||4.6750
|-
|...
||...
||...
||...
|-
|
||
|| ...
||
|}
Bifurcation parameter is a root point of period- component. This series converges to the Feigenbaum point = −1.401155...... The ratio in the last column converges to the first Feigenbaum constant.
Other maps also reproduce this ratio; in this sense the Feigenbaum constant in bifurcation theory is analogous to in geometry and in calculus.
References
Mathematical constants | Feigenbaum's First Constant | [
"Mathematics"
] | 878 | [
"Mathematical constants",
"Mathematical objects",
"Numbers",
"nan"
] |
76,115,113 | https://en.wikipedia.org/wiki/Feigenbaum%27s%20second%20constant | The second Feigenbaum constant or Feigenbaum's alpha constant ,
is the ratio between the width of a tine and the width of one of its two subtines (except the tine closest to the fold). A negative sign is applied to when the ratio between the lower subtine and the width of the tine is measured.
These numbers apply to a large class of dynamical systems (for example, dripping faucets to population growth).
A simple rational approximation is × × = .
References
Mathematical constants | Feigenbaum's second constant | [
"Mathematics"
] | 110 | [
"Mathematical analysis",
"Mathematical analysis stubs",
"Mathematical objects",
"nan",
"Mathematical constants",
"Numbers"
] |
76,116,167 | https://en.wikipedia.org/wiki/Monocyte%20distribution%20width | Monocyte distribution width (MDW) is a cytometry-based parameter that measures the range of variation of monocytes. If the parameter is available, it is reported as part of the standard complete blood count (CBC) with differential.
The parameter was FDA cleared as an early sepsis indicator for ER patients in 2019 for Beckman Coulter.
MDW serves as an indicator for early screening of sepsis in conjunction with CRP and PCT and for differentiating false positive blood cultures.
References
Blood tests | Monocyte distribution width | [
"Chemistry",
"Biology"
] | 106 | [
"Blood tests",
"Biotechnology stubs",
"Biochemistry stubs",
"Biochemistry",
"Chemical pathology"
] |
76,116,761 | https://en.wikipedia.org/wiki/Intermediate%20public%20transport | Intermediate public transport (IPT), also known as paratransit, encompasses a range of hired road vehicles that offer flexible passenger transportation services. Unlike traditional public transit, IPT does not operate on a fixed schedule and may vary in its adherence to set routes.
The concept of intermediate public transport exhibits considerable variation between developed and developing nations. In developed countries, it is typically a flexible, demand-responsive form of public transportation designed to provide point-to-point service. These systems are generally well-structured and organized. In developing countries, IPT often operates as an informal, cost-effective alternative to formal transportation modes. It tends to be unorganized and subject to minimal government regulation, serving as a prevalent form of spontaneous public transport that facilitates quick and convenient travel.
The importance of IPT may extends beyond mobility, as it can also contribute to the economic well-being of those who operate these services. In some cases, drivers of vehicles such as tempos and autorickshaws can earn a substantial daily income, which supports their livelihoods.
Defining IPT in Different Contexts
The concept of intermediate public transport exhibits considerable variation between developed and developing nations. In developed countries, it is typically a flexible, demand-responsive form of public transportation designed to provide point-to-point service. These systems are generally well-structured and organized. In developing countries, IPT often operates as an informal, cost-effective alternative to formal transportation modes. It tends to be unorganized and subject to minimal government regulation, serving as a prevalent form of spontaneous public transport that facilitates quick and convenient travel.
Historical Context
The concept of intermediate public transport (IPT) has evolved over time, adapting to the changing needs of urban mobility in different parts of the world. In developing countries, IPT emerged organically as a response to inadequate formal public transportation systems. In India, for example, cycle rickshaws appeared in the 1940s, followed by auto-rickshaws in the 1950s. These modes filled the gap between walking and formal public transport, providing flexible and affordable mobility options for short to medium distances. In Africa and parts of Asia, informal minibus services known variously as matatus, dalla-dallas, or jeepneys have long served as a crucial form of public transport. These evolved from shared taxis and grew to become an integral part of urban mobility in many cities.The rise of digital technologies in the 21st century has led to new forms of IPT, such as app-based ride-hailing services. These platforms have blurred the lines between traditional taxis and paratransit, offering new levels of flexibility and convenience.Today, IPT continues to play a vital role in urban mobility worldwide, particularly in developing countries where it often serves as the primary mode of public transport for many residents.
References
Sustainable transport
Paratransit services
Demand-responsive transport | Intermediate public transport | [
"Physics"
] | 580 | [
"Physical systems",
"Transport",
"Sustainable transport",
"Transport stubs"
] |
76,117,043 | https://en.wikipedia.org/wiki/Mating%20press | Mating press is a sex position that usually consists of one participant performing downwards sexual penetration into the receiving partner, often holding their legs down or around the head. It is often seen as a more aggressive version of the missionary position, pushing the legs even further, and often associated with aspects of dominance and submission. While the act has been practiced in many countries, it is most often associated with Japanese sex culture, where the term was created, and the act was popularized.
Etymology
The name is derived from the Japanese word 種付けプレス, which is made up of tanetsuke (種付け), which means "mating", and puresu (プレス) which is the English word "press" in katakana. The word was first coined by mangaka Takatsu Keita.
Practice
The act has been performed in some shape and form in various countries throughout history, although without a name. Since then, the act and name have been associated with Japan and credited with popularizing the act. The name and term have become popular outside of Japan thanks in part to the popularity of hentai and Japanese pornography. The term was only mainly used in pornographic manga and eventually expanded to real pornography. The term was mainly used as an online meme outside of Japan, but eventually came to be used more often in outside pornographic industries too.
See also
Woman on top
Bukkake
Ekiben (sexual act)
Gokkun
Pornography in Japan
References
Japanese sex terms
Pornography terminology
Sexual acts
Sexuality in Japan
Sex positions | Mating press | [
"Biology"
] | 308 | [
"Sexual acts",
"Behavior",
"Sexuality",
"Mating"
] |
76,117,102 | https://en.wikipedia.org/wiki/NAURA%20Technology%20Group | NAURA Technology Group (Naura; ) is a partially state-owned publicly listed Chinese company that manufactures semiconductor chip production equipment. It is currently the largest semiconductor equipment manufacturer in China.
History
In September 2001, Beijing Electronics Holdings, a government SASAC entity initiated the establishment of Beijing Sevenstar Electronics (Sevenstar Electronics).
On 16 March 2010, the company held its initial public offering on the ChiNext of Shenzhen Stock Exchange. It was the biggest gainer for mainland China stocks on that day where its initial price of 33 yuan per share jumped 79% percent to 59 yuan.
In 2016, Sevenstar Electronics acquired Beijing North Microelectronics (NMC) from its parent, Beijing Electronics Holdings. NMC specialized in Silicon etching and Physical vapor deposition (PVD) equipement. On 24 February 2017, after the company restructured following its acquisition, it was renamed to NAURA Technology Group.
In January 2018, the Committee on Foreign Investment in the United States (CFIUS) approved Naura's purchase of Akrion Systems, a Pennsylvania-based rival that was a supplier of advanced wafer surface preparation technology. This was the first takeover of an American company by a Chinese one that was approved since Donald Trump became President of the United States. Prior to that the Trump administration had blocked all Chinese acquisitions of US target companies as a result of the China–United States trade war.
In October 2022, Naura told its American employees in China to stop taking part in R&D activities to comply with the United States New Export Controls on Advanced Computing and Semiconductors to China. Naura stated its subsidiary, Beijing Naura Magnetoelectric Technology was on the Bureau of Industry and Security unverified list although it accounted for only 0.5% of the company's annual revenue. Its share price dropped 20% that week. A week later, US trade officials from American embassy in Beijing held talks with executives of Naura.
In December 2022, Beijing Naura Magnetoelectric Technology was removed from the Bureau of Industry and Security unverified list after their bona fides were able to be verified.
In February 2023, Yangtze Memory Technologies reduced its equipment purchase orders by 70% from Naura. The cancellation orders stated in October 2022 which was around the same time the US export controls came into effect.
In January 2024, Naura stated it expected its 2023 revenue to increase by around half from a year earlier as its technology developments allowed it fulfil local demands and gain a greater market share in the country.
In February 2024, Bloomberg News reported that Naura was one of the top investment picks among Wall Street firms such as Barclays and Sanford C. Bernstein. A company comparable to Applied Materials, it would be able to fulfill local market demands in China and fill the void left by foreign firms being unable to continue doing business due to geopolitical restrictions.
In April 2024, it was reported that Naura was starting research on lithography systems.
In September 2024, Taiwanese authorities accused eight mainland Chinese technology companies which included Naura of illegally poaching talent from Taiwan. Naura denied poaching local workers and stated its office in Taiwan operated in accordance with local laws and regulations.
In December 2024, Naura was targeted in a new round of US export controls and added to the United States Department of Commerce's Entity List.
Business lines
Naura has four business lines:
Semiconductors (plasma etching, PVD, CVD, oxidation/diffusion, cleaning system, and annealing)
Vacuum technology (heat treatment, crystal growth and magnetic material)
Lithium battery equipment
Precision components (resistors, capacitors, crystal devices, and module power supplies)
See also
Semiconductor industry in China
Applied Materials
References
External links
2001 establishments in China
2010 initial public offerings
Companies based in Beijing
Companies listed on the Shenzhen Stock Exchange
Electronics companies established in 2001
Equipment semiconductor companies
Government-owned companies of China
Semiconductor companies of China
Companies in the CSI 100 Index
2001 in Beijing | NAURA Technology Group | [
"Engineering"
] | 817 | [
"Equipment semiconductor companies",
"Semiconductor fabrication equipment"
] |
76,117,139 | https://en.wikipedia.org/wiki/Loneliness%20epidemic | The loneliness epidemic is an ongoing trend of loneliness and social isolation experienced by people across the globe. The uptick may have begun in the 2010s and was exacerbated by the isolating effects of social distancing, stay-at-home orders, and deaths during the COVID-19 pandemic.
History of the study of loneliness
The concept of a "loneliness epidemic" began to gain attention before the COVID-19 pandemic, with researchers pointing to rising rates of social isolation in the 2000s. Robert D. Putnam’s 2000 study Bowling Alone was one of the first to identify loneliness as an epidemic, highlighting how decreased participation in civic life and community groups was weakening social bonds in the United States.
In 2010, a systematic review and meta analysis by Holt-Lunstad, Smith, and Layton, stated that the "modern way of life in industrialized countries" is greatly reducing the quality of social relationships, partly due to people no longer living in close proximity with their extended families. The review notes that from 1990 to 2010, the number of Americans reporting no close confidants had tripled.
A number of studies were published shortly before the COVID-19 pandemic by academics such as Claude S. Fischer and Eric Klinenberg. While it wasn't always clear to all scholars that loneliness was an "epidemic," the studies did conclude that loneliness is indeed a serious issue, having a severe health impact on millions of people.
In early 2021, shortly after the onset of the COVID-19 pandemic, Harvard’s Making Caring Common Project released its first Loneliness in America report, which linked the crisis to pandemic-driven isolation and identified significant loneliness, particularly among young adults and parents of young children. That same year, Richard Weissbourd's follow-up study found that around 36% of American adults reported chronic loneliness, a trend mirrored across several countries where lockdowns and social distancing intensified social isolation.
In Europe, a comparative overview of the prevalence and determinants of loneliness and social isolation in the pre-COVID period was conducted by the Joint Research Centre of the European Commission. The findings indicated that 8.6% of the adult population in Europe experience frequent loneliness and 20.8% experience social isolation, with eastern Europe recording the highest prevalence of both phenomena.
In Australia, the annual national Household, Income and Labour Dynamics in Australia (HILDA) Survey has reported a steady 8% rise in agreement with the statement "I often feel very lonely" between 2009 and 2021, responses indicating "strongly agree" rose steadily by over 20% in that same time period. This is a reversal of the trend seen from the start of the survey in 2001 until 2009, where these figures had both been steadily decreasing.
Together, these studies have spurred more recent efforts to examine and address loneliness as a public health priority, in the U.S. and globally.
Causes of loneliness
Some authors identified individualism as a root cause of loneliness in Western societies, particularly in the U.S. Scholars like Robert N. Bellah, in Habits of the Heart, argue that American individualism weakens communal bonds, leading to social isolation and loneliness. Similarly, Wendell Berry’s essays emphasize how modern, profit-oriented social structures undermine community connection.
Technology use is another significant factor. According to Capita, an American think tank that specializes in the study of loneliness, the overuse of digital and social media, especially among young people, often reduces real-life interactions and deepens feelings of isolation. In another essay titled The Good, The Bad & The Lonely, Capita highlighted that Gen Z experiences heightened loneliness, as they report lower engagement in community activities. Richard Weissbourd's research supports these findings, linking social media and screen time to disconnection among U.S. youth.
Economic challenges were also found to compound these issues. Low-wage workers and individuals in economically distressed areas experience higher levels of loneliness due to limited social mobility and access to community resources. Chris Arnade’s book Dignity describes how economic inequality isolates individuals, especially in lower-income communities.
Meanwhile, a 2021 survey on the impact of parenthood on loneliness indicates that although parents report slightly more social support than non-parents, single-person households and low social support environments face increased isolation risks. Timothy P. Carney’s Family Unfriendly highlights policies that fail to support stay-at-home parents, contributing to isolation and mental health challenges.
Global responses to the loneliness epidemic
Since the 2010s, large-scale initiatives have been launched in countries including the U.S., Australia and the U.K.
In November 2023, the World Health Organization declared loneliness a "global public health concern" and launched an international commission to study the problem.
United States
In the U.S., the loneliness epidemic has increasingly become a topic of public debate, particularly since May 2023, when the U.S. Surgeon General Vivek Murthy published a United States Department of Health and Human Services advisory on the impact of the epidemic of loneliness and isolation. The report outlined the health risks of loneliness, including heart disease, stroke, and dementia, and likened the dangers of loneliness to other public health threats such as smoking and obesity.
Following Murthy's advisory, bipartisan legislative proposals emerged, notably the National Strategy for Social Connection Act led by Senator Chris Murphy. This proposed act aims to establish a federal office focused on addressing loneliness and promoting social connectedness through community and public health initiatives.
The conversation around loneliness has since broadened to include state-level responses and greater public awareness, underscoring the need for systemic efforts to counteract this public health challenge.
In September 2024, the New York Times reported that metrics indicative of loneliness were especially common among Americans who lack a college degree.
Bibliography
Bellah, R. N. (1985). Habits of the Heart: Individualism and Commitment in American Life. University of California Press. .
Putnam, R. D. (2001). Bowling Alone: The Collapse and Revival of American Community. Simon & Schuster. .
Holt-Lunstad, J.; Smith, T. B.; Layton, J. B. (2010). "Social Relationships and Mortality Risk: A Meta-analytic Review". PLOS Medicine.
Berry, W. (2010). The Art of the Commonplace: The Agrarian Essays of Wendell Berry. ReadHowYouWant. .
DiJulio, B.; Hamel, L.; Muñana, C.; Brodie, M. (2018). "Loneliness and Social Isolation in the United States, the United Kingdom, and Japan: An International Survey". KFF.
Arnade, C. (2019). Dignity: Seeking Respect in Back Row America. Penguin Publishing Group. .
Baarck, J; D'hombres, B; Tintori, G (2021). "Loneliness in Europe before and during the COVID-19 pandemic". Joint Research Centre of the European Commission.
Capita. (2022). Social Connection Report: The Ties That Bind and Nurture. Capita.org.
Surkalim, D. L.; Luo, M.; Eres, R.; Gebel, K.; van Buskirk, J.; Bauman, A; et al. (2022). "The prevalence of loneliness across 113 countries: systematic review and meta-analysis". The BMJ.
Carney, T. P. (2024). Family Unfriendly: How Our Culture Made Raising Kids Much Harder Than It Needs to Be. HarperCollins. .
References
Epidemiology
Public health
COVID-19 pandemic
World Health Organization
Mental health in the United States
Social issues in the United States | Loneliness epidemic | [
"Environmental_science"
] | 1,599 | [
"Epidemiology",
"Environmental social science"
] |
76,117,343 | https://en.wikipedia.org/wiki/Space%20One | , or Space One (スペースワン), is a Japanese aerospace manufacturer, orbital launch service provider, and spaceport operator. It is a private spaceflight company developing and operating the KAIROS orbital launch vehicle for small satellite launches; KAIROS flew its unsuccessful maiden flight in March 2024. The company was founded by investments from (a listed subsidiary of Canon), IHI Aerospace (a subsidiary of IHI Corporation), Shimizu Corporation and the Development Bank of Japan in July 2018.
Rockets
The namesake of the KAIROS rocket, or Kii-based Advanced & Instant Rocket System, is the Greek word Kairos, which means 'time' and is also an alternate spelling of the name of Caerus, the Greek deity of luck and opportunity.
Launch site
Shimizu Corporation constructed Space One's own launch site for KAIROS, named Spaceport Kii, as Japan's first-ever private sector spaceport, in Kushimoto, Wakayama, Japan between 2019 and 2021. The launch site provides access to various orbit inclinations.
This spaceport is accessible from Tokyo International Airport (Haneda Airport) via Nanki–Shirahama Airport in approximately 2 hours and 20 minutes, and from Kansai International Airport in approximately 2 hours and 30 minutes.
Accidents and incidents
Inaugural flight explosion
On March 13, 2024, Kairos rocket exploded moments into its maiden voyage, aiming to become the first Japanese private company to deploy a satellite into orbit. The 59-foot solid-fueled rocket disintegrated shortly after liftoff from the Kii peninsula in western Japan, leaving behind debris and a cloud of smoke; there were no immediate reports of injuries.
See also
Interstellar Technologies, another private orbital launch services provider in Japan
List of launch service providers
List of private spaceflight companies
List of spacecraft manufacturers
References
External links
Official Website (in English)
Space program of Japan
Commercial spaceflight
Private spaceflight companies
Technology companies established in 2018
Aerospace companies of Japan | Space One | [
"Astronomy"
] | 403 | [
"Outer space stubs",
"Outer space",
"Astronomy stubs"
] |
76,117,481 | https://en.wikipedia.org/wiki/Space%20One%20KAIROS | The , or Kii-based Advanced & Instant Rocket System, is a Japanese solid-fuel rocket designed to launch small satellites of mass up to 250 kg to low Earth orbit and up to 150 kg to sun-synchronous orbit by the private spaceflight company Space One. It consists of 3 solid fuel powered stages and a liquid propellant upper stage.
Namesake
The namesake of the KAIROS rocket is the Greek word Kairos, which means the subjective 'right time' as contrasted with Chronos which is the objective clock time. Kairos is also an alternate spelling of the name of Caerus, the Greek deity of luck and opportunity.
Manufacture
manufactures the KAIROS rocket at Tomioka Plant in the city of Tomioka, Gunma Prefecture.
Launches
Launch site
Launches are planned from Spaceport Kii in Kushimoto, Wakayama, Japan, a dedicated launch site built by Shimizu Corporation. This spaceport is accessible from Tokyo International Airport (Haneda Airport) via Nanki–Shirahama Airport in approximately 2 hours and 20 minutes, and from Kansai International Airport in approximately 2 hours and 30 minutes.
First launch
The first launch was planned on 9 March 2024 but was postponed because a ship was spotted in the "maritime warning area" set up in waters near the launch pad. The launch eventually took place on 13 March 2024, but the vehicle exploded five seconds after liftoff. The remains of the rocket and payload fell close to the launch pad, but no substantial damage was found. Space One announced several hours later that the autonomous flight termination system could have activated and ended the mission. On 25 August 2024, the company's director confirmed that a destruct command was issued on the rocket. The AFTS detected a speed and level of thrust on the first stage that was lower than was modeled. Because this was the first rocket launch in Japan that used a flight safety system capable of intervening in a launch without human involvement, the destruct criteria were set to be particularly conservative.
Second flight
The second flight took place on 18 December 2024, which was cancelled because of failed rocket shortly after launch.
The mission was planned to carry five satellites, including four CubeSats and one microsatellite.
These satellites include payloads developed by Taiwan Space Agency, Space Cubics LLC, Terra Space Inc. and jp/ LAGRAPO Ltd, as well as an additional satellite owned by an unnamed customer. The rocket began tumbling during 1st stage burn. The flight was terminated some time after.
List of launches
See also
Interstellar Technologies, another private orbital launch services provider developing orbital launch vehicles in Japan
Comparison of orbital launchers families
Comparison of orbital launch systems
References
External links
Official Website (in English)
Solid-fuel rockets
Space launch vehicles of Japan
Expendable space launch systems | Space One KAIROS | [
"Astronomy"
] | 569 | [
"Outer space stubs",
"Outer space",
"Astronomy stubs"
] |
76,117,622 | https://en.wikipedia.org/wiki/Welding%20table | A welding table is a type of workbench used for holding workpieces during welding. They are made of fireproof and electrically conductive materials, and often have good possibilities for clamping workpieces down, providing increased stability, precision and security. In addition to a welding machine and personal protective equipment, they are often used together with accessories such as measuring tools, magnets and angles. Some welders build their own welding tables.
Fire safety
They are often made of steel, and some welding tables have a zinc plating to prevent slag from sticking to the table. The table can withstand high temperatures and splashes of hot slag, unlike a wooden table which can catch fire more easily. This reduces the risk of risk of fire.
Grounding
They are often connected to ground to prevent voltage leaks during work and to protect the welder from electrical shocks, but also to prevent radio noise from the welding process which otherwise can affect nearby electronics.
Ergonomics
Most tables have an adjustable height so that the welder can sit or stand in a comfortable and ergonomic position.
Some also have the possibility for the work surface to be tilted or rotated so that the workpiece can get the desired position and orientation (pose).
Mass, size and mobility
The space available and the size of the things to be welded will dictate the need. Some tables are very heavy and solid, and can withstand heavy workpieces, while other models are lighter and can only withstand lighter workpieces.
Stationary tables
Some tables are heavy, tough and stable, and are meant to be stationary in one place in a workshop, and are capable of withstanding loads from very heavy objects. A permanent welding table usually has a length of at least 2 meters.
Mobile tables
Some tables are portable so that they can be moved around the workshop as needed, for example in the form of mobile trolley tables with lockable wheels. There has been a trend with smaller tables that can be put together to form a longer work surface depending on the shape and size of what is to be welded, following a similar principle as a sawhorse. Some tables are extendable so that the size can be reduced or increased as necessary.
See also
Workbench (woodworking)
References
Welding
Workbenches | Welding table | [
"Engineering"
] | 461 | [
"Welding",
"Mechanical engineering"
] |
76,117,705 | https://en.wikipedia.org/wiki/IAU%20designated%20constellations%20by%20geographical%20visibility | The International Astronomical Union (IAU) designates 88 constellations. In the table below, they are listed by geographical visibility according to latitude as seen from Earth, as well as the best months for viewing the constellations at 21:00 (9 p.m.).
List
Notes and references
See also
Lists of astronomical objects
IAU designated constellations by area
Lists of stars by constellation
Geographical Visibility
IAU constellations | IAU designated constellations by geographical visibility | [
"Astronomy"
] | 86 | [
"Lists of constellations",
"Sky regions",
"IAU constellations",
"Constellations"
] |
76,117,971 | https://en.wikipedia.org/wiki/John%20Purkis | John Purkis (1781 – 10 April 1849), was an English organist and teacher. He was blind at birth. A child prodigy, Purkis studied with Thomas Grenville (circa 1744–1827), also blind, and the organist at the Foundling Hospital in London. He became organist at St Margaret's Chapel at the age of nine, and then, aged 12, at St Olave Southwark, after a public competition and three day poll. His salary there was £30.
From 1804 until his death Purkis was organist at St Clement Danes, and also (after 1825) at St Peter's Walworth. He was consultant to the organ building firm Flight and Robinson during the construction of the Apollonicon a self-playing barrel organ, presented to the public for the first time in 1817. Over the next 21 years he performed popular Saturday afternoon recitals on the instrument at the firm's showroom, 101, St Martin's Lane. At the recitals Purkis often played fantasias on opera themes that were later published as piano pieces by William Hodsoll, and these became very popular with home pianists in the 1820s. Rachel Cowgill has called the Apollonicon recitals "virtually synonymous with the establishment of the public organ recital in England....the first to be held in a secular venue and run on a purely commercial basis".
Purkis was also a skilled violinist and harpist. With woodwind instrument maker Thomas Scott he formed the Scott & Purkis partnership to manufacture a double flageolet, taking out a patent in December 1805 for "an instrument on the flageolette principle, so constructed as a single instrument that two parts of a musical composition can be played thereon at the same time by one person". A tutorial book by Purkis was published. But rival William Bainbridge, inventor of the six finger-hole "improved English flageolet" in 1803, produced a more popular double flageolet, for which he was granted a patent in 1810.
In 1811 Purkis went through a series of operations, performed by Sir William Adams of Exeter, that gained him some limited sight. His pupils included the organist and music historian William Smith Rockstro. He died, aged 68, in April 1849.
References
External links
Compositions by John Purkis at IMSLP
Keyboard instruments
Mechanical musical instruments
1781 births
1849 deaths
Blind classical musicians
English classical organists
19th-century English classical composers
19th-century English male musicians
19th-century keyboardists
English male classical organists | John Purkis | [
"Physics",
"Technology"
] | 523 | [
"Physical systems",
"Mechanical musical instruments",
"Machines"
] |
76,118,274 | https://en.wikipedia.org/wiki/Outcome%20switching | Outcome switching is the practice of changing the primary or secondary outcomes of a clinical trial after its initiation. An outcome is the goal of the clinical trial, such as survival after five years for cancer treatment. Outcome switching can lead to bias and undermine the reliability of the trial, for instance when outcomes are switched after researchers already have access to trial data. That way, researchers can cherry pick an outcome which is statistically significant.
Problem
Outcome switching can undermine the reliability of the trial, for instance when outcomes are switched when researchers already have access to the trial data. It can lead to bias in terms of benefits and harms. For example, when the findings using the original protocol were statistically insignificant, a study may cherry pick a new outcome measure that is statistically significant. If there are a large number of outcomes to choose from, it is likely at least one will show significant findings, assuming no correction is made for multiple testing. Incomplete or misleading reporting of outcomes is an example of unethical research practice.
Possible solutions
Primary outcomes for clinical trials need to be defined upfront to prevent a biased selection of outcomes. Some medical journals require adherence to the CONSORT standards, which require authors to document any deviations from the initial study protocol and explain why changes were made. For instance, JAMA and the British Medical Journal require inclusion of the CONSORT checklist. When pre-specified outcomes are defined but unclear, researchers still have wriggle room to choose the most favourable option. A clear pre-defined outcome is therefore important to avoid outcome switching.
Study authors may engage in outcome switching due to high pressures to publish. It is more difficult to publish negative results, especially in high-impact journals. Registered reports—a type of journal article where editors pledge to publish clinical trials irrespective of their results—may help combat this pressure to produce positive results. Initial peer review takes place based on the methodology and the reasoning behind the study.
Prevalence
Despite problems with outcome switching, the practice is common. Changes in primary outcome metrics are present in nearly one in three studies. Outcome switching also occurs frequently in follow-up studies. In an analysis of oncology trials, outcome switching was more common in studies with a male first author, and in studies funded by non-profits. One study analysed outcome switching in five top medical journals, writing letters for each misreported trial outcome. Journal editors and clinical trial authors typically responded dismissively when concerns were raised, misrepresenting ethical standards and including ad hominem attacks.
Examples
A drug against major depressive disorder, paroxetine, was marketed for children and teenagers for years, based on a flawed trial that involved outcome switching. The trial's protocol had described two primary and six secondary outcomes by which it would measure efficacy. The data showed that, according to those eight outcomes, paroxetine was no more effective than placebo. According to Melanie Newman, writing for the BMJ, "[t]he drug only produced a positive result when four new secondary outcome measures, which were introduced following the initial data analysis, were used instead. Fifteen other new secondary outcome measures failed to throw up positive results."
See also
Data dredging
References
Research ethics
Clinical research ethics
Clinical trials
Biostatistics
Scientific misconduct
Medical research
Evidence-based medicine
Medical ethics | Outcome switching | [
"Technology"
] | 671 | [
"Research ethics",
"Scientific misconduct",
"Ethics of science and technology"
] |
59,533,010 | https://en.wikipedia.org/wiki/Methanedithiol | Methanedithiol is an organosulfur compound with the formula H2C(SH)2. A seldom used chemical, it form when formaldehyde reacts with hydrogen sulfide under pressure:
This reaction competes with formation of trithiane:
Methanedithiol forms a solid dibenzoate derivative upon treatment with benzoic anhydride:
Methanetrithiol is also known.
References
Thiols
Functional groups
Organosulfur compounds
Foul-smelling chemicals | Methanedithiol | [
"Chemistry"
] | 98 | [
"Organic compounds",
"Organosulfur compounds",
"Thiols",
"Functional groups"
] |
59,533,535 | https://en.wikipedia.org/wiki/Smog%20tower | Smog towers or smog free towers (see below for other names) are structures designed as large-scale air purifiers to reduce air pollution particles (smog). This approach to the problem of urban air pollution involves air filtration and removal of suspended mechanical particulates such as soot and requires energy or power. Another approach is to remove urban air pollution by a chimney effect in a tall stack or updraft tower, which may be either filtered or released at altitude as with a solar updraft tower and which may not require operating energy beyond what may be produced by the updraft.
World’s first air cleaning tower
The world's first smog-free tower was built by Dutch artist Daan Roosegaarde. It was unveiled in September 2015 in Rotterdam and later similar structures toured or were installed in
Beijing and Tianjin, China, Kraków, Poland, Anyang, South Korea and Abu Dhabi. The 7-meter (23 ft) tall tower uses patented positive ionisation technology and is expected to clean 30,000 m3 of air per hour.
Gallery
World’s largest air cleaning tower
In 2016, a tower has been built in Xi'an, Shaanxi to tackle the city's pollution. It was funded by the provincial government and costs US$2 million. The running cost is $30000 per year. It is under testing by researchers at the Institute of Earth Environment of the Chinese Academy of Sciences.
The experimental demonstration urban updraft tower is cleaning the air in central China with little external energy input. A 60-metre urban chimney is surrounded by solar collector. This project was led by Cao Jun Ji, a chemist at the Chinese Academy of Sciences' Key Laboratory of Aerosol Chemistry and Physics. This work has since been published on, with the performance data and modelling.
"I like to tell my students that we don’t need to be medical doctors to save lives ... If we can just reduce the air pollution in major metropolitan areas by 20 percent, for example, we can save tens of thousands of lives each year ... I hope that people will realize that this is a really effective and cheap way to solve the PM2.5 problem."
“In the case of India, their population is more packed together, so the towers will be more effective in mitigating PM2.5 … At least during the next 10-15 years, they can use them to provide relief to residents while they invest in clean energy technology.”
—David Pui, Regents Professor and LM Fingerson/TSI Chair in Mechanical Engineering of the University of Minnesota, explained.
Other towers
India
, there are at least eight smog towers in India, some of which are smaller in scale:
Connaught Place (around 80 ft; since Aug 2021)
Anand Vihar (around 80 ft)
Lajpat Nagar Central market (20 ft; since Jan 2020)
Gandhi Nagar market (12 ft)
Krishna Nagar market (12 ft)
Bangalore (15 more maybe installed later)
Chandigarh (24–25 m; water used to remove pollutants)
Jaipur
Projects under development
In Delhi, India Kurin Systems is developing a tall smog tower, called the "Kurin City Cleaner". It is different from Daan Roosegaarde's Smog Tower in that it won't depend on the ionization technique to clean the air. The H14 grade HEPA Filter, known for being able to clean up to 99.99% of the particulate matter, will be used instead, together with a pre-filter and activated carbon. It is claimed the tower will filter air for up to 75,000 people within a radius. and cleaning more than 32 million cubic metres of air every day. ZNera Space proposed Lutyens' Delhi smog tower network.
Efficacy
In 2023, some researchers from IIT Bombay conducted a study on the smog tower in Connaught Place, Delhi. They found that the tower's air cleaning efficiency varies with distance. At the source, it operates at 50% efficiency, but this drops to 30% just 50 meters away, and further decreases to slightly over 10% at a distance of 500 meters. They also found that the filter housing was not properly sealed, allowing contaminated air to circumvent the filtration process.
Reception
There are air pollution experts who view smog filtration tower projects with scepticism. For example, Professor Alastair Lewis, Science Director at the NCAS, has argued that static air cleaners, like the prototypes in Beijing and Delhi, cannot process enough city air, quickly enough, to make a meaningful difference to urban pollution. He said that it was "easier to come up with technologies and schemes that stop harmful emissions at source, rather than to try to capture the resulting pollution once it's free and in the air".
Noting that the Delhi tower would be powered by (mostly) coal-fired electricity, Sunil Dahiya from India's Centre for Research on Energy and Clean Air has commented that "so we will only be adding to pollution elsewhere in the country". According to The Times, environmentalists said that "given the city[Delhi]'s size and the scale of its pollution, 2.5 million smog towers would be needed to clean its air". As a refute, "The objective is not to clear entire Delhi's air, it is to create special zones where people can breathe," Anwar Ali Khan, the engineer in charge of the project said.
See also
Air-supported structure
Biofilter
CityTrees
Domed city
Green building
Green wall
List of tallest buildings and structures
Sustainable city
Direct air capture
References
Further reading
(machine translation, original page in Chinese)
External links
"Filtration Solutions to Mitigate Coronavirus Aerosol and PM2.5 Pollutants" by Professor David Pui David Y. H. Pui talked about the smog free towers (SALSCS) in Xi'an and Delhi (video starts from 33:44)
IFC Mall installs extra-large air purifiers to manage indoor fine dust (machine translation, original text in Korean)
Development of Passive/Active integrated module device for fine dust free zone implementation (2nd year) | Bucheon City, Korea's first fine dust reduction device pilot operation (machine translation, original text in Korean)
Nutan Labs Smog Towers, Nutan Labs is the producer of the tower in Bangalore
This device can purify air over 500 sqm
WAYU air purifiers on Delhi roads turn dustbins, spittoons
Vast grid of filter towers proposed across Delhi to combat toxic smog
Studio Symbiosis proposes Aũra towers to alleviate air pollution in Delhi
Air pollution
Building biology
Energy conversion
Filters
Industrial gases
Gas technologies
Scrubbers
Solar power | Smog tower | [
"Chemistry",
"Engineering"
] | 1,397 | [
"Chemical equipment",
"Building engineering",
"Filters",
"Scrubbers",
"Industrial gases",
"Filtration",
"Chemical process engineering",
"Building biology"
] |
59,534,742 | https://en.wikipedia.org/wiki/Unimog%2070200 | The Unimog 70200 is the first series production model of the Unimog series, made by . It was manufactured in Boehringer's Göppingen plant from June 1948 to April 1951. In total, 600 units of the 70200 were made. Manufacture of the Unimog was sold to Daimler-Benz in October 1950, where it was modified for mass production. The mass-production optimised Unimog is known as Unimog 2010.
The Unimog 70200 name was chosen because of Boehringer's cost centre. All Unimog 70200 vehicle identification numbers begin with 70200. Minuscules were used to differentiate between certain models. It is said that approximately 100–120 Unimog 70200s have been preserved.
History
Development
The Unimog 70200 was invented by German engineer Albert Friedrich, who worked as an aircraft engine designer with Daimler-Benz during World War II. After the Morgenthau Plan was published, Friedrich decided to develop an agricultural vehicle, in case post-war Germany would become an agricultural country. Friedrich considered a vehicle similar to an agricultural tractor – with a hitch and PTOs – but much more capable offroad, and equipped with all-wheel drive. Furthermore, a canvas roof and a flatbed were key elements of Friedrich's design. To reach a top speed of , Friedrich considered a power output of sufficient.
The earliest plans were conceptualised in late 1945; in November that year, a production order was granted by the US Military Administration, meaning that it was officially believed that the vehicle would not have any military purpose. Friedrich was eventually allowed to develop the vehicle, and permission was granted to build ten prototypes. For this purpose, Friedrich signed a development contract with Erhard & Söhne, a jewelry factory from Schwäbisch Gmünd, which at that time produced gold and silver handicrafts. Two engineers were assigned to the project, but in January 1946, a third engineer, Heinrich Rößler, joined the team. Heinrich Rößler, also a former Daimler-Benz employee, carried out the main development work. He later became the head of Unimog development at Daimler-Benz.
The first technical drawings were completed in March 1946. Rößler put a lot of emphasis on the functionality of the vehicle; for instance, the track width measures , which equals two rows of potatoes. Both the front and rear axles are live axles with reduction gears. They are technically identical, welded together from just two preformed metal panels each, and have only four drive joints. This design made the axles simple and cheap to produce. Later plans also included differential locks for the axles and the gearbox, and coil springs with hydraulic shock absorbers instead of leaf springs for the suspension.
First prototypes and engine development
The first prototypes were completed in late 1946 at Erhard & Söhne. They were fitted with the M 136 Otto engine. The first four prototypes were either destroyed or lost. On 9 October 1946, the first test drive with the vehicle was conducted. Later that year, the vehicle was presented to experts and engineers. Hans Zabel, and engineer who worked on the project, coined the acronym "Unimog" by making a note on one of the drawings; Zabel called the vehicle an "Universal-Motor-Gerät" (Universal-Motor-Gadget), which lead to the Unimog name. On 20 November 1946, the name was officially adopted. Later, the U 5 and U 6 prototypes were made at the Boehringer plant in Göppingen. These are the oldest known Unimogs, and they were already equipped with the OM 636 Diesel engine from the factory. Since its restoration, the U 5 protoype has been on static display at the agricultural museum of the University of Hohenheim, whereas the U 6 prototype has been on display at the Unimog museum in Gaggenau.
Daimler-Benz had successfully brought the Mercedes-Benz OM 138 Diesel engine for passenger cars to market in the mid-1930s. Development of a successor to this engine started in the days of World War II. In 1948, said successor was ready for mass production, but Mercedes-Benz passenger cars were not yet scheduled to be equipped with this engine. In 1947, Unimog engineers had decided to abandon the M 136 Otto engine and to use a Diesel engine instead for the series production Unimog. As they had a good relationship with Daimler-Benz, the engineers decided to use the OM 138's successor, which at the time was still in development. This is the reason why the OM 138's successor – known as OM 636 – was already used in pre-series production Unimogs prior to its 1949 introduction in Mercedes-Benz passenger cars.
Manufacture at Boehringer and sale of Unimog
The official Unimog presentation was held in 1947. Erhard & Söhne was not able to mass-produce the Unimog, which is why Gebr. Boehringer in Göppingen was awarded a manufacturing contract. This allowed Boehringer, originally a tool manufacturer, to avoid allied dismantling. Erhard & Söhne became a supplier for Unimog production. Pre-series production finally started in 1948; the same year, the Unimog was exhibited by Mercedes-Benz at the DLG-exhibition in Frankfurt, with 150 orders for the Unimog placed. The first patent for the Unimog's portal axles was filed on 21 November 1948 under the 950 430 patent number. Series production was started in February 1949.
Boehringer did not use modern methods of mass production, instead, all Unimogs were solely built by hand. Starting in 1949, 90 additional employees worked on the Unimog project, and a sales and distribution network as well as a customer service team were established. The highest monthly production rate at the time was 50 units per month. This was insufficient to meet customer demands, and it was foreseeable that Boehringer would be incapable of manufacturing the Unimog over a long period of time. Therefore, Unimog was sold to Daimler-Benz in October 1950. Production in Göppingen ceased by April 1951. Then, production was moved over to the Mercedes-Benz plant in Gaggenau. Production of the 70200's successor, the Unimog 2010, began in June 1951. Erhard & Söhne, who manufactured the Unimog axles, remained a supplier for Daimler-Benz until 1963.
Technical description
The Unimog 70200 is a compact tractor, measuring approximately in length. It has four wheels of the same size, four hydraulic brakes, a ladder frame made of U-shaped sections, and front and rear live axles with portal gears and bolted axle covers. The axles are coil sprung, and fitted with hydraulic shock absorbers. The suspension uses torque tubes, transverse links, and panhard rods. The tyres are multi purpose (6.5 – 18 in): designed for both on-road and off-road use.
The Unimog 70200 uses an OM 636.912 passenger car engine. The OM 636 is a straight-four, water-cooled, naturally aspirated precombustion chamber, diesel engine with overhead valves with a displacement of and developing . The engine is installed longitudinally, slightly inclined, and has an electric starter motor. Unlike the following OM 636 family engines, the OM 636.912 has two valve covers.
The gearbox is a constant mesh gearbox with six forward and two reverse gears, allowing a speed range of . The rear axle is permanently driven; when front-wheel drive is enabled – which does not require depressing the clutch pedal – different amounts of torque are sent to the front axle and rear axle.
Bibliography
Lutz Nellinger: Der Unimog: Arbeitstier und Kultmobil. Komet, Köln 2016, .
Carl-Heinz Vogler: Unimog 411: Typengeschichte und Technik. GeraMond, München 2014, .
Carl-Heinz Vogler: Typenatlas Unimog. Alle Unimog-Klassiker seit 1946 bis 1993. GeraMond, München 2015, .
References
Tractors | Unimog 70200 | [
"Engineering"
] | 1,711 | [
"Engineering vehicles",
"Tractors"
] |
59,535,516 | https://en.wikipedia.org/wiki/Templewood%20Primary%20School | Templewood Primary School is a primary school in Pentley Park, Welwyn Garden City, Hertfordshire, England. It is one of a number of modernist schools commissioned by the Hertfordshire County Council in the 20th century and is a Grade II* listed building.
References
Grade II* listed buildings in Hertfordshire
Primary schools in Hertfordshire
Schools in Welwyn Garden City
Prefabricated buildings
Modernist architecture in England
Grade II* listed schools
Community schools in Hertfordshire
Educational institutions with year of establishment missing | Templewood Primary School | [
"Engineering"
] | 95 | [
"Building engineering",
"Prefabricated buildings"
] |
59,535,565 | https://en.wikipedia.org/wiki/NGC%20985 | NGC 985 is a ring galaxy in the constellation of Cetus. It is located about 550 million light years away from Earth, which means, given its apparent dimensions, that NGC 985 is approximately 160,000 light years across. It was discovered by Francis Leavenworth in 1886. It is a type 1 Seyfert galaxy.
NGC 985 is characterised by its ring shape. It is believed it was formed as a result of a galaxy merger. Further evidence supporting this theory is the observation of a second nucleus in NGC 985. When observed in infrared light, a second nucleus was found 3.8 arcseconds northwest of the active nucleus. It is much redder than the rest of the galaxy, indicating the presence of old stars. It has been suggested that the collision between a disk galaxy with another galaxy caused the formation of the ring and displaced the nucleus of the galaxy, creating an empty ring. Based on the kinematics of the galaxy, the secondary nucleus belonged to the intruder galaxy, while the active nucleus is associated with the main stellar component.
As is common with merger remnants, NGC 985 has increased star formation rate, and as a result shines bright in the infrared. The total infrared luminosity of NGC 985 is and it is characterised as a luminous infrared galaxy. The total molecular gas mass of the galaxy is estimated to be . Very large molecular clouds exist near the nuclei. They may be clouds gathering around the nucleus in the process of forming a disk around the two nuclei or molecular clouds disrupted by an outflow from the nucleus of the galaxy.
NGC 985 is a powerful X-ray source, detected by ROSAT. It is a complex X-ray source, whose spectrum cannot be accounted for by a simple power law at 0.6 keV and suggests the presence of a warm absorber. The hard X-ray emission on the other hand is characterised by a simple power law. The X-ray flux, especially soft X-rays, diminished in NGC 985 in 2013. The variability of the X-ray and ultraviolet emission from the nucleus was observed using the XMM-Newton and Hubble Space Telescope respectively. These observations revealed the presence of outflowing wind from an accretion disk formed around a supermassive black hole that obstructed the nucleus in soft X-rays and UV. The nucleus is otherwise seen unobstructed.
References
External links
NGC 985 on SIMBAD
Ring galaxies
Peculiar galaxies
Seyfert galaxies
Luminous infrared galaxies
Interacting galaxies
Cetus
Discoveries by Francis Leavenworth
Astronomical objects discovered in 1886
0985
09817
Markarian 1048 | NGC 985 | [
"Astronomy"
] | 535 | [
"Cetus",
"Constellations"
] |
59,537,159 | https://en.wikipedia.org/wiki/C26H34O4 | {{DISPLAYTITLE:C26H34O4}}
The molecular formula C26H34O4 (molar mass: 410.55 g/mol, exact mass: 410.2457 u) may refer to:
CP 42,096
Methestrol dipropionate
Trenbolone hexahydrobenzylcarbonate, or trenbolone cyclohexylmethylcarbonate | C26H34O4 | [
"Chemistry"
] | 93 | [
"Isomerism",
"Set index articles on molecular formulas"
] |
59,537,838 | https://en.wikipedia.org/wiki/Chip%20on%20board | Chip on board (COB) is a method of circuit board manufacturing in which integrated circuits (e.g. microprocessors) are attached (wired, bonded directly) to a printed circuit board, and covered by a blob of epoxy. Chip on board eliminates the packaging of individual semiconductor devices, which allows a completed product to be less costly, lighter, and more compact. In some cases, COB construction improves the operation of radio frequency systems by reducing the inductance and capacitance of integrated circuit leads.
COB effectively merges two levels of electronic packaging: level 1 (components) and level 2 (wiring boards), and may be referred to as "level 1.5".
Construction
A finished semiconductor wafer is cut into dies. Each die is then physically bonded to the PCB.
Three different methods are used to connect the terminal pads of the integrated circuit (or other semiconductor device) with the conductive traces of the printed circuit board.
Flip chip
In "flip chip on board", the device is inverted, with the top layer of metallization facing the circuit board. Small balls of solder are placed on the circuit board traces where connections to the chip are required. The chip and board are passed through a reflow soldering process to make the electrical connections.
Wire bonding
In "wire bonding", the chip is attached to the board with an adhesive. Each pad on the device is connected with a fine wire lead that is welded to the pad and to the circuit board. This is similar to the way that an integrated circuit is connected to its lead frame, but instead the chip is wire-bonded directly to the circuit board.
Glob-top
Flexible circuit board
In "tape-automated bonding", thin flat metal tape leads are attached to the semiconductor device pads, then welded to the printed circuit board.
In all cases, the chip and connections are covered with an encapsulant to reduce entry of moisture or corrosive gases to the chip, to protect the wire bonds or tape leads from physical damage, and to help dissipate heat.
The printed circuit board substrate may be assembled into the final product, for example, as in a pocket calculator, or, in the case of a multi-chip module, the module may be inserted in a socket or otherwise attached to yet another circuit board. The substrate wiring board may include heat-dissipating layers where the mounted devices handle significant power, such as in LED lighting or power semiconductors. Or, the substrate may have low-loss properties required at microwave radio frequencies.
COB LED modules
COBs containing arrays of light-emitting diodes have made LED lighting more efficient.
LED COBs include a layer of silicone containing yellow Ce:YAG phosphor that encapsulates the LEDs and turns the blue light of the LEDs into white light. The COB is usually built on an aluminum PCB that provides good thermal conductivity to a heatsink. COB LEDs could be compared with multi chip modules or hybrid integrated circuits since all three can incorporate multiple dies into a single unit.
COB variants are also used in newer LED bulbs as in this case the substrate can be either glass, sapphire or sometimes regular phenolic.
With a transparent substrate the LED chips may be installed "upside down" shining through for higher outcoupling. Typically they are glued to the substrate with UV setting glue, interconnects attached, and the encapsulant and phosphor applied in a single step with a back reflective coating applied to channel light out of the device.
References
Electronics manufacturing
Printed circuit board manufacturing | Chip on board | [
"Engineering"
] | 751 | [
"Electrical engineering",
"Electronic engineering",
"Electronics manufacturing",
"Printed circuit board manufacturing"
] |
59,538,271 | https://en.wikipedia.org/wiki/Newest%20vertex%20bisection | Newest Vertex Bisection is an algorithmic method to locally refine triangulations. It is widely used in computational science, numerical simulation, and computer graphics. The advantage of newest vertex bisection is that it allows local refinement of triangulations without degenerating the shape of the triangles after repeated usage.
In newest vertex bisection, whenever a triangle is to be split into smaller triangles, it will be bisected by drawing a line from the newest vertex to the midpoint of the edge opposite to that vertex. That midpoint becomes the newest vertex of the two newer triangles. One can show that repeating this procedure for a given triangulation leads to triangles that belong to only a finite number of similarity classes.
Generalizations of newest vertex bisection to dimension three and higher are known. Newest vertex bisection is used in local mesh refinement for adaptive finite element methods, where it is an alternative to red-green refinement and uniform mesh refinement.
References
Algorithms | Newest vertex bisection | [
"Mathematics"
] | 206 | [
"Applied mathematics",
"Algorithms",
"Mathematical logic"
] |
59,539,440 | https://en.wikipedia.org/wiki/Artificial%20intelligence%20in%20government | Artificial intelligence (AI) has a range of uses in government. It can be used to further public policy objectives (in areas such as emergency services, health and welfare), as well as assist the public to interact with the government (through the use of virtual assistants, for example). According to the Harvard Business Review, "Applications of artificial intelligence to the public sector are broad and growing, with early experiments taking place around the world." Hila Mehr from the Ash Center for Democratic Governance and Innovation at Harvard University notes that AI in government is not new, with postal services using machine methods in the late 1990s to recognise handwriting on envelopes to automatically route letters. The use of AI in government comes with significant benefits, including efficiencies resulting in cost savings (for instance by reducing the number of front office staff), and reducing the opportunities for corruption. However, it also carries risks (described below).
Uses of AI in government
The potential uses of AI in government are wide and varied, with Deloitte considering that "Cognitive technologies could eventually revolutionize every facet of government operations". Mehr suggests that six types of government problems are appropriate for AI applications:
Resource allocation - such as where administrative support is required to complete tasks more quickly.
Large datasets - where these are too large for employees to work efficiently and multiple datasets could be combined to provide greater insights.
Experts shortage - including where basic questions could be answered and niche issues can be learned.
Predictable scenario - historical data makes the situation predictable.
Procedural - repetitive tasks where inputs or outputs have a binary answer.
Diverse data - where data takes a variety of forms (such as visual and linguistic) and needs to be summarised regularly.
Mehr states that "While applications of AI in government work have not kept pace with the rapid expansion of AI in the private sector, the potential use cases in the public sector mirror common applications in the private sector."
Potential and actual uses of AI in government can be divided into three broad categories: those that contribute to public policy objectives; those that assist public interactions with the government; and other uses.
Contributing to public policy objectives
There are a range of examples of where AI can contribute to public policy objectives. These include:
Receiving benefits at job loss, retirement, bereavement and child birth almost immediately, in an automated way (thus without requiring any actions from citizens at all)
Social insurance service provision
Classifying emergency calls based on their urgency (like the system used by the Cincinnati Fire Department in the United States)
Detecting and preventing the spread of diseases
Assisting public servants in making welfare payments and immigration decisions
Adjudicating bail hearings
Triaging health care cases
Monitoring social media for public feedback on policies
Monitoring social media to identify emergency situations
Identifying fraudulent benefits claims
Predicting a crime and recommending optimal police presence
Predicting traffic congestion and car accidents
Anticipating road maintenance requirements
Identifying breaches of health regulations
Providing personalised education to students
Marking exam papers
Assisting with defence and national security (see and respectively)
Assisting public interactions with government
AI can be used to assist members of the public to interact with government and access government services, for example by:
Answering questions using virtual assistants or chatbots (see below)
Directing requests to the appropriate area within government
Filling out forms
Assisting with searching documents (e.g. IP Australia's trade mark search)
Scheduling appointments
Various governments, including those of Australia and Estonia, have implemented virtual assistants to aid citizens in navigating services, with applications ranging from tax inquiries to life-event registrations.
Gerrymandering
Gerrymandering is an insidious method of influencing political process. Depending on the objective of its use, the application of artificial intelligence to redraw districts based on voter distribution and demographic datasets can either contribute to impartiality, or sustain partisan gains for interested stakeholders in the election process.
Other uses
Other uses of AI in government include:
Translation
Language interpretation pioneered by the European Commission's Directorate General for Interpretation and Florika Fink-Hooijer.
Drafting documents
Potential benefits
AI offers potential efficiencies and costs savings for the government. For example, Deloitte has estimated that automation could save US Government employees between 96.7 million to 1.2 billion hours a year, resulting in potential savings of between $3.3 billion to $41.1 billion a year. The Harvard Business Review has stated that while this may lead a government to reduce employee numbers, "Governments could instead choose to invest in the quality of its services. They can re-employ workers' time towards more rewarding work that requires lateral thinking, empathy, and creativity — all things at which humans continue to outperform even the most sophisticated AI program."
Risks
Risks associated with the use of AI in government include AI becoming susceptible to bias, a lack of transparency in how an AI application may make decisions, and the accountability for any such decisions.
AI in governance and the economic world might make the market more difficult for companies to keep up with the increases in technology. Large U.S. companies like Apple and Google are able to dominate the market with their latest and most advanced technologies. This gives them an advantage over smaller companies that do not have the means of advancing as far in the digital technology fields with AI.
See also
AI for Good
Applications of artificial intelligence
Artificial general intelligence
Artificial intelligence and elections
Civic technology
e-government
Existential risk from artificial general intelligence
Government by algorithm
Lawbot
Project Cybersyn
Regulation of artificial intelligence
Singleton (global governance)
References
Further reading
Applications of artificial intelligence
Government
E-government
Government by algorithm | Artificial intelligence in government | [
"Engineering"
] | 1,128 | [
"Government by algorithm",
"Automation"
] |
59,539,544 | https://en.wikipedia.org/wiki/Carbon%20pricing%20in%20Canada | Carbon pricing in Canada is implemented either as a regulatory fee or tax levied on the carbon content of fuels at the Canadian provincial, territorial or federal level. Provinces and territories of Canada are allowed to create their own system of carbon pricing as long as they comply with the minimum requirements set by the federal government; individual provinces and territories thus may have a higher tax than the federally mandated one but not a lower one. Currently, all provinces and territories are subject to a carbon pricing mechanism, either by an in-province program or by one of two federal programs. , the federal minimum tax was set at per tonne of equivalent, set to increase to in 2030.
In the absence of a provincial system, or in provinces and territories whose carbon pricing system does not meet federal requirements, a regulatory fee is implemented by the federal Greenhouse Gas Pollution Pricing Act (GHGPPA), which passed in December 2018. In provinces where the fee is levied, 90% of the revenues are returned to tax-payers.
The carbon tax is levied because of a need to combat climate change, which resulted in federal commitments to the Paris Agreement. According to NASA's Jet Propulsion Laboratory (JPL), the air today contains 400 ppm of while the CO2 level average over the past 400,000 years was between 200 ppm and 280 ppm.
Saskatchewan never had a carbon pricing system and other provinces—Manitoba, Ontario, New Brunswick, and Alberta—have opted out of previous provincial carbon tax systems. Revenue from the federal GHGPPA, which came into effect in April 2019, is redistributed to the provinces, either through tax credits to individual residents or to businesses and organizations that are affected by the tax but are unable to pass on the cost by raising consumer prices.
The introduction of the tax was met with political resistance, mainly by the Conservative Party of Canada which attempted to "make the carbon tax the single issue" of the 2019 federal election campaign. This argument did not succeed, as the Canadian voting public supported parties that also supported the carbon tax, leading CBC News to declare Canada's carbon tax to be "the big election winner" and "the only landslide victor" in this election. Similarly, legal challenges to the law failed on March 25, 2021, when the Supreme Court of Canada rejected the 2019 appeal of the provinces of Manitoba, Ontario, Alberta, and Saskatchewan, ruling in Reference re Greenhouse Gas Pollution Pricing Act that GHGPPA was constitutional.
History
Alberta becomes first jurisdiction in North America to put price on carbon
In 2003, Alberta signaled its commitment to manage greenhouse gas emissions by passing the Climate Change and Emissions Management Act. One of the first actions taken under this legislation was to develop a mandatory reporting program for large emitters in Alberta.
In March 2007, Alberta passed Specified Gas Emitters Regulation. The first compliance cycle was from July 1 to December 31, 2007.
Quebec implements first carbon tax
In June 2007, Quebec implemented the first carbon tax in Canada which was expected to generate $2 million annually.
On December 11, 2008, ExxonMobil CEO Rex Tillerson said that a carbon tax is preferable to a cap-and-trade program which "inevitably introduces unnecessary cost and complexity". A carbon tax is "a more direct, more transparent and more effective approach". Tillerson added that he hoped that the revenues from a carbon tax would be used to lower other taxes so as to be revenue neutral.
2008: Dion election proposal
An unpopular revenue-neutral carbon tax was proposed in 2008 during the Canadian federal election, by Stéphane Dion, then leader of the Liberal Party. It was Dion's main platform and it allegedly contributed to the defeat of the Liberal Party with its worst share of the popular vote in the country's history.
The Conservative party, who won the 2008 election, had promised to implement a North American-wide cap-and-trade system for greenhouse gases. During the 2008 Canadian federal election, the Conservative party promised to develop and implement greenhouse gas emissions trading by 2015, also known as cap and trade, that encourage a certain type of behaviour through economic incentives regarding the control of emissions and pollution.
2014 Ecofiscal Commission
In 2014, public policy economists and superannuated politicians came together to begin discussions on what would become the Canada's Ecofiscal Commission. The Commission was established with the participation of Paul Martin, Jim Dinning, Preston Manning, and Jack Mintz on November 4, 2014, and became the leading advocacy group in Canada for carbon pricing. They published reports in 2015, 2016, and 2017.
2015: Trudeau pledges to act if elected
In February 2015, Justin Trudeau announced that he would impose carbon pricing if elected. The proposed system would resemble the medicare model in which provinces would design systems suitable for their needs with the federal government setting national targets and enforcing principles.
2016: Paris Agreement
The Paris Agreement () is an agreement within the United Nations Framework Convention on Climate Change (UNFCCC), dealing with greenhouse-gas-emissions mitigation, adaptation, and finance, signed in 2016. The agreement's language was negotiated by representatives of 196 state parties at the 21st Conference of the Parties of the UNFCCC in Le Bourget, near Paris, France, and adopted by consensus on 12 December 2015. Under the Paris Agreement, each country must determine, plan, and regularly report on the contribution that it undertakes to mitigate global warming. No mechanism forces a country to set a specific target by a specific date.
A special report by The Guardian in partnership with Climate Action Tracker, compared pledges made by some 200 countries that participated in the 2015 United Nations round of talks on a "new climate deal" hosted in Paris. The co-authors wrote an in-depth analysis of 14 key countries and blocs, including Canada. The article, which summarized the report, said that Canada climate targets were the "weakest ... of any major industrialised economy which experts say was a "direct result" of Stephen Harper government's hard line policies" and its "promotion" of the "vast reserves of tar sands in Alberta" that are highly polluting".
By December 2016, the ten provinces and the Canadian government presented their "executive, mitigation and adaptation" strategies towards a clean economy. The "extensive document"—"Pan-Canadian Framework on Clean Growth and Climate Change"—"lean[-ed] heavily on carbon pricing".
In 2018, Canada passed the GHGPPA, implementing a revenue-neutral carbon tax starting in 2019, which applies only to provinces whose carbon pricing systems created for their jurisdictions did not meet federal requirements. Revenue from the carbon tax was to be redistributed to the provinces.
According to a report by the Canadian Chamber of Commerce (CCC) released on December 13, 2018, Canada's largest business group endorsed the carbon pricing introduced by the federal government saying it offers flexibility and is the "most efficient way to cut emissions" and "solidly backs carbon pricing." According to a December 13 CTV News article, Stewart Elgie, from the Ottawa-based Environment Institute at the University of Ottawa, the CCC's "endorsement of the carbon tax as the most efficient emissions-cutting tool" and its support of "Canada's investments in clean technology at home and abroad", provides the Canadian economy with a "major opportunity...to market itself in a low-carbon future".
In December 2018, the Senate Committee on Agriculture and Forestry submitted their report based on a year-long study on the "impacts of climate change and carbon pricing on agriculture, agri-food and forestry". Although some witnesses raised concerns that Canada's international competitiveness could be diminished compared with producers "who do not bear these additional, carbon-related costs". The Committee noted that a "study of the effects of British Columbia's carbon tax — which launched in 2008 — suggested the province's international competitiveness was not diminished". The report recommended that Environment and Climate Change Canada, formerly known as Environment Canada, or EC consider exemptions for agricultural activities under the GHGPPA, with "special attention to competitiveness for producers and food affordability for Canadians". The Committee recommended exempting fuels used for heating or transportation in farming activities.
2018: Canadian government enacts GHGPPA
The Parliament of Canada passed the Greenhouse Gas Pollution Pricing Act (GHGPPA) in the fall of 2018 under Bill C-74. The GHGPPA refers to charge or pricing instead of taxation. The charge which will rise to $50 per tonne of CO2 by 2022, begins at in 2019 and increases by per year until 2022. Through the GHGPPA, provinces have the flexibility to create their own solutions to deal with GHG emissions in their own jurisdictions. Through the GHGPPA all provinces are required to place a minimum price of a tonne of GHG emissions by January 1, 2019. The tax will be retroactive to January. The tax has increased to in 2020 and to per tonne as of April 2021.
The federal government plans to send an annual rebate ranging from adequate emissions pricing plans. For example, if a family of 4 in Ontario pays per month extra for gas, home heating and other costs, that same family will receive in annual rebates. Compared to the in costs, the GHGPPA should leave them better off in 2019. The rebate benefit increases each year as the carbon price and the rebate both gradually rise. Taxpayers had to request the Climate Action Incentive Payment (CAIP) rebate on their annual income tax return until filing their 2021 tax return, from which time eligibility for the rebate is automatic and the taxpayer sent a cheque or a direct deposit is made into their bank account.
In her October 23, 2018 Power & Politics podcast, Vassy Kapelos interviewed Dominic LeBlanc, the Minister of Intergovernmental Affairs, Northern Affairs and Internal Trade, Saskatchewan Premier Scott Moe, and Ontario Minister of Environment Rod Phillips.
Carbon pricing in Canada is forecast by Environment Canada to remove 50-60 MT of emissions from the air annually by 2022, which represents about 12% of all Canadian emissions. However, Canada needs to reduce emissions to 512 MT by 2030 to meet its Paris Climate Change accord. This would mean reducing annual emissions by about 200MT from the 2018 levels. In addition to carbon pricing, the government is pursuing a range of additional policies including improving fuel standards, energy efficiency, and closing coal plants.
Forecast economic impact
A May 22, 2018 report by the Parliamentary Budget Officer (OFC) showed that carbon pricing would have at most a minor impact on the economy, with an increase in GDP in 2022 of about , or 0.1% of GDP.
According to a 2018 report, British Columbia, which has had a carbon price since 2008, had the fastest growing economy in Canada.
In their April 25, 2019 report, Canada's Parliamentary Budget Officer estimated that the federal government "will generate in carbon pricing revenues in 2019-20." The report said that the "vast majority of revenues () will be generated through the fuel charge; the balance, roughly , will be generated by output-based pricing." According to the PBO report, there will be an estimated increase in carbon pricing revenues of by 2023-24.— from the fuel charge proceed and the rest from the OBPS—a "trading system for large industry, known as the output-based pricing system (OBPS)".
However, the Canadian Revenue Agency has declared that, as of June 3, 2019, the average payment to households was less than previously estimated. It amounted to in New Brunswick, in Ontario, in Manitoba and in Saskatchewan.
2018: Constitutional challenges of GHGPPA
In 2019, the provinces of Manitoba, Ontario, Saskatchewan brought their case to the Supreme Court of Canada. On March 25, 2021, the justices rejected their appeal, ruling in Reference re Greenhouse Gas Pollution Pricing Act that the GHGPPA was constitutional.
2020: Updated federal carbon price, reaching $170 in 2030
In December 2020, the federal government released an updated plan with a per year increase in the carbon pricing, reaching in 2025 and in 2030.
2023 targeted relief for low-income and rural households
In October 2023 Prime Minister Justin Trudeau announced that the federal government was granting a carbon exemption on heating oil from 2023 through 2027 because the price of heating oil increased by 75% in 2022. Natural gas, which is used by households that are better off, now costs one-half to one-quarter the cost of heating oil. There are only about 3% of Canadians who still use heating oil, and they are mainly located in the Atlantic provinces. They are also mainly low-income and rural, so the exemption was intended for this demographic. Opposition critics say that this move is politically motivated, as the Liberal government has more Members of Parliament in the Atlantic provinces. Environmentalists criticize the decision, saying that it undermines the carbon pricing scheme.
Carbon price in individual provinces and territories
By 2018, Quebec (2007), British Columbia (2008), Alberta, Ontario, Manitoba and Nova Scotia had carbon-pricing policies in place. By 2017, Metro Vancouver was "exploring road fares and other fee-based mechanisms to address traffic congestion". Ontario cancelled their cap and trade system in 2018. The outlines of a new climate plan for Ontario, which did not include any carbon pricing system, was unveiled in November 2018.
Manitoba, Ontario, Saskatchewan, and New Brunswick refused to impose their own emissions pricing so the federal pricing came into effect on April 1. Residents of the four provinces pay more for gasoline and heating fuel. The "starting rate added 4.4 cents to the price of a litre of gas, about four cents to a cubic metre of natural gas". The price of propane, butane and aviation fuel will also increase. Residents will receive rebates on their income tax returns. Amounts will vary with each province. In Saskatchewan for example, a family of four will receive $609 in 2019.
British Columbia
The Government of British Columbia introduced a carbon tax in 2008.
British Columbia was the first Canadian province to join the Western Climate Initiative (WCI), which was established in February 2007 by the governors of Arizona, California, New Mexico, Oregon, and Washington to reduce greenhouse gas emissions. The WCI became an international partnership when BC joined. By 2011, BC's preference was for its existing carbon tax as opposed to the cap and trade proposed by the WCI.
In 2013, Angel Gurría, then-Secretary-General of the Organisation for Economic Co-operation and Development (OECD), said that the "implementation of British Columbia's carbon tax is as near as we have to a textbook case, with wide coverage across sectors and a steady increase in the rate" over a period of five years.
According to a November 2015 article in The Atlantic, after British Columbia's provincial government introduced a carbon tax in 2008, greenhouse emissions were reduced, "fossil fuel use in British Columbia [had fallen] by 16 percent, as compared to a 3 percent increase in the rest of Canada, and its economy ... outperformed the rest of the country." This proved that carbon tax benefits were "no longer theoretical" and that they did not hinder economic growth.
Quebec
Quebec participates in an international emissions trading scheme with the US state of California.
In June 2007, Quebec implemented a carbon tax on energy distributors, producers, and refiners, the first Canadian province to do so. When announcing the new tax, Quebec Natural Resources Minister Claude Béchard said that industries would absorb the tax, which would total in revenue annually, instead of passing on the cost to consumers. Of the 50 companies affected, the hardest hit would be oil companies, who would pay "about a year for gasoline, for diesel fuel, and for heating oil". The tax would also affect natural gas distributors who would pay about and electricity distributor Hydro-Québec who would pay for its Sorel-Tracy, Quebec-based thermal energy plant.
Saskatchewan
The Premier of Saskatchewan, Scott Moe, has spoken emphatically against the GHGPPA. The Government of Saskatchewan released a report entitled "Prairie Resilience: A Made-in-Saskatchewan Climate Change Strategy" which he said in an October 23, 2018 interview with CBC's Vassy Kapelos, has been accepted by the federal government as meeting GHGPPA requirements. The federal government assured residents of Saskatchewan that "all direct proceeds collected in Saskatchewan under the federal pollution pricing backstop system" would be paid "through direct payments to individuals and families and investments to reduce emissions, save money, and create jobs". For example, a family of four would "receive $609 in 2019".
Alberta
In July 2007, Alberta enacted the Specified Gas Emitters Regulation, Alta. Reg. 139/2007, (SGER). This tax exacts a $15/tonne contribution by companies that emit more than 100,000 tonnes of greenhouse gas annually that do not reduce their CO2 emissions per barrel by 12 percent, or buy an offset. In January 2016, the contribution required by large emitters increased to $20/tonne. The tax fell heavily on oil companies and coal-fired electricity plants. It was intended to encourage companies to lower emissions while fostering new technology. The plan only covered the largest emitters, who produced 70% of Alberta's emissions. Critics charged that the smallest energy producers are often the most casual about emissions and pollution. The carbon tax is currently $20 per tonne. Because Alberta's economy is dependent on oil extraction, the majority of Albertans opposed a nationwide carbon tax. Alberta also opposed a national cap and trade system. The local tax retains the proceeds within Alberta.
On 23 November 2015, the Alberta government announced a carbon tax scheme similar to British Columbia's in that it would apply to the entire economy. All businesses and residents paid tax based upon equivalent emissions, including the burning of wood and biofuels. The tax came into force in 2017 at $20 per tonne.
On 4 June 2019 a carbon tax repeal bill was enacted.
In November 2015 Premier Rachel Notley and Alberta Environment Minister Shannon Phillips announced Alberta's carbon tax.
In his Maclean's 2015 article, economist Trevor Tombe wrote that "[p]ricing carbon is one of the most sensible policy prescriptions to address greenhouse gas emissions". Tombe listed the advantages and disadvantages. The carbon tax provides a "new source of revenue for the government". The tax is a "far more efficient means of lowering greenhouse gas emissions than regulatory approaches." As part of the process of researching and implementing the carbon tax, the Alberta government worked with a panel chaired by University of Alberta economist Andrew Leach to study a carbon tax based on "sensible, evidence-based policy advice", which Tombe described as "a model for other jurisdictions". The price of the carbon tax began at a tonne in 2017, rose to a ton in 2018 and was tied to a 2% increase based on rising inflation, which Tombe considered to be "reasonable". Tombe estimated the impact of the carbon tax on the 3 "most carbon-intensive consumer purchases". He estimated an increase in the price of gasoline of c. 6.7 cents per litre when the a tonne tax came into effect. Natural gas prices would increase by about . "[L]ow to middle-income households" would "receive compensation".
Premier Kenney joined like-minded premiers, including Doug Ford of Ontario, Scott Moe of Saskatchewan and Brian Pallister of Manitoba, in a lawsuit against the federal Liberal government on the carbon tax. The Court of Appeal of Alberta ruled against the federal government. This decision was later overturned when the Supreme Court of Canada ruled that the federal carbon tax was constitutional.
The first piece of legislation introduced by the newly-elected Premier of Alberta, Jason Kenney, was Bill 1: An Act to Repeal the Carbon Tax. The bill repeals the provincial carbon tax, but it will be replaced by the federal carbon levy.
Ontario
The Ontario Climate Change Mitigation and Low-Carbon Economy Act, 2016 passed by the government of Kathleen Wynne established a standard cap and trade system which integrates with the Western Climate Initiative (WCI) providing access to an "even greater market to buy and sell the most cost effective carbon credits." Gary Goodwin called it the "best and most integrated solution to the problem of emissions."
In September 2017, the Wynne government of Ontario joined the Western Climate Initiative (WCI), which was established in February 2007 by the governors of Arizona, California, New Mexico, Oregon, and Washington to reduce greenhouse gas emissions. *April 24, 2007: British Columbia joined with the five western states, turning the WCI into an international partnership with the goal of developing a multi-sector, market-based program to reduce greenhouse gas emissions.and link its cap-and-trade system with Quebec's and California's in January 2018. This harmonized carbon market will be the second largest in the world, trailing only the EU Emissions Trading System (ETS) and will feature joint permit auctions. Because it allows for permit trading between jurisdictions, linked cap-and-trade systems achieve lower-cost mitigation actions across jurisdictions than an unlinked system.
In October 2018, the newly-elected Progressive Conservative government under premier Doug Ford, cancelled the previous cap and trade system as he had promised in his electoral campaign. In November, the Ontario government unveiled a climate plan which did "not include any kind of price on emissions".
Gas station decals
In April 2019, the provincial government introduced the Federal Carbon Tax Transparency Act as part of its budget, which makes it mandatory for all gas stations (excluding those situated on Indian reserves) to display government-commissioned decals on their pumps informing customers of the claimed "cost" of the carbon tax—increasing gas prices by 4.4 cents per-litre, and increasing gas prices by up to 11 cents per-litre by 2022. The decals contain a URL for a page on the Ontario web site that explains its positions on the tax, but the decals do not mention the rebate programs. Gas stations may be inspected at "all reasonable times" for compliance with the Act, and owners may be fined for their first violation, and per-day if they persist. The fines increase to for corporations. The act became effective August 30, 2019.
Federal Minister of Environment and Climate Change Catherine McKenna accused the Ford government of "wasting taxpayers' dollars on misleading stickers" which failed to acknowledge the rebate programs "or the cost of inaction on climate change". The Act was criticized by the Ontario NDP, with MPP Peter Tabuns accusing Ford of "threatening private business owners with massive fines for failing to post Conservative Party advertisement[s]". Fellow MPP Taras Natyshak issued a letter to the Chief Electoral Officer, alleging that the decals should be considered partisan campaign advertising under the Canada Elections Act due to the then-upcoming federal election. The government defended the decals and Act, considering it "transparency" that reminds Ontario residents of the "costs" of the Liberal carbon tax. Green Party of Ontario leader Mike Schreiner accused Ford of "forcing businesses to be complicit in his anti-climate misinformation campaign", and invited gas stations to help him inform the public that "climate change will cost us more" with his own version of the decal.
The Canadian Civil Liberties Association took the Ontario government to court over the mandatory stickers, arguing the messages were “a form of compelled political expression.” In September 2020, the Ontario Superior Court of Justice sided with CCLA, ruling that Ford's mandatory gas-pump decals attacking federal carbon-pricing measures are unconstitutional and violated business owners' freedom of expression.
Northwest Territories
The Government of the Northwest Territories implemented a carbon price that took effect in September 2019.
Output Based Pricing System (OBPS)
Most aspects of the federal government's Output Based Pricing System (OBPS) announced in December 2018, "which targets greenhouse gas emissions from large, industrial facilities", are similar to Alberta's Carbon Competitiveness Incentive Regulation (CCIR) which was also similar to Alberta's 2007 Specified Gas Emitters Regulation (SGER). The three programs had a "price on carbon emissions" and a "system of allocations through which firms receive some number of emissions credits for free." The OBPS rules apply to large facilities in Ontario, New Brunswick, Manitoba, Prince Edward Island, Saskatchewan, Yukon and Nunavut—the "provinces covered by the federal backstop policy." The OBPS covers a "relatively small share of emissions in the provinces it affects." Most emissions come from smaller emitters which "will be covered in large part by the carbon price". A University of Alberta professor of economics named Andrew Leach blogged that "Much of the coverage of this system has framed the OBPS as an exemption from emissions pricing for large emitters, but that hides the importance of the two, linked programs – the carbon price and the output-based allocation of credits."
In the spring of 2018, the federal government had "proposed that all fossil fuel-burning generating stations be treated the same with the first 420 tonnes of greenhouse gases per gigawatt hour of electricity produced exempt from carbon taxes and everything above that subject to a charge."
CBC reported in October 2018 that "natural gas stations face carbon taxes on emissions above 370 tonnes, oil on emissions above 550 tonnes and coal above 800 tonnes, a major concession to coal plants."
Carbon tax and the 2019 federal election
In June 2018, John Ivison wrote in the National Post that the Conservative Party were attempting to make the carbon tax "the single issue" of the 2019 federal election campaign. He argued that Andrew Scheer's leadership had interpreted Doug Ford's election as premier of Ontario as "an explicit rejection of the carbon tax".
Carbon tax debate
The federal carbon pricing system in Canada has been the subject of significant debate and controversy.
Since 2016, the Mining Association of Canada, has supported carbon pricing as a way of responding to climate change. A 2024 Ecological Economics journal literature review based on public communications on carbon pricing of the 100 largest oil and gas companies said that 54% of those oil and gas companies with a stated policy on carbon taxes express support for such measures, with the percentage rising to 78% among the top 50 companies.
The debate around carbon pricing intensified in early February 2023, with a polar vortex causing record-breaking cold weather. Pierre Poilievre, who has been the leader of the Conservative Party of Canada and the leader of the Official Opposition since 2022, blamed the dramatic increase in heating bills on the carbon price, commonly referred to as the "carbon tax," on his social media accounts, which reached half a million viewers. In June 2023, Poilievre launched his 'Axe the Tax' campaign in the Atlantic provinces, just days before the region faced increased gas prices when carbon pricing came into force in that region on 1 July 2023, following four years of an exemption.
Poilievre pledged in July 2023, that he would repeal the carbon tax if the Conservatives form government under him in the 2025 federal election.
In March 2024, Poilievre called for a non-confidence vote in the federal government in the House of Commons to prevent the 1 April increase in the carbon price. Prior to the April 1 carbon tax increase, Poilievre crossed the country with his 'Axe the Tax' rallies.
With the backing of both the Bloc and the NDP, the government survived.
A group, called Nationwide Protest Against Carbon Tax, organized protests that took place at about fifteen locations across Canada, with dozens of partipants at some locations. Their goal was to slow traffic on major highways and at borders to protest the increase of the federal consumer carbon price of $15-per-tonne.
By 2 April 2024, two hundred economists had signed an open letter refuting Poilievre's stance on carbon pricing.
See also
Climate change in Canada
Acts and Regulations for carbon pricing
Notes
References
Emissions reduction
Taxation in Canada
Environmental tax
Environmental law in Canada
Carbon finance
Low-carbon economy
Energy policy of Canada | Carbon pricing in Canada | [
"Chemistry"
] | 5,794 | [
"Greenhouse gases",
"Emissions reduction"
] |
53,288,657 | https://en.wikipedia.org/wiki/Khirbet%20Almit | Khirbet Almit is an archaeological site in the West Bank, occupied from the Middle Bronze Age to the Ottoman period. It is located in the Judaean Desert about 4 km northeast of Mount Scopus and about 1.5 km southeast of 'Anata. The site is situated on the top of two peaks of one hill at an altitude of 638 meters above sea level, near Nahal Zimri and on the border of the Nahal Prat Nature Reserve.
Excavation history
The site of Khirbet Almit has been excavated several times. Rescue excavations were conducted in the years 1973, 1981, and 1999, in various areas in the site.
Archeology
The center of the site is on the southwestern peak, where there are remains of buildings, a hiding complex dating to the Bar Kokhba revolt, residential and storage caves, rock-cut tombs and additional graves, water cisterns, and terraces. Excavations has also found Yehud coins.
Apart from the excavated caves, the surveyors noted a burial cave on the western slope with five steps at its entrance. Inside the cave, there is a small hall with a small burial chamber, which includes four niches. Near the burial cave, there is a columbarium cave with about 70 niches. In the northwestern part of the peak, two water cisterns are carved into the chalk rock. To the south of them are the remains of a winepress, including a treading floor, a collection pit, and a section of mosaic.
At the top of the peak is a square structure with 4 meters long walls. In the northeastern part at the top of the peak, there is an industrial underground complex that had several agricaltural uses, including an oil press.
To the south of the southwestern peak is the tomb of Sheikh 'Abd es-Sallam, a Muslim saint who migrated from Morocco and founded the village of 'Anata. Next to this tomb are modern Arab graves.
References
Iron Age Asia
Coordinates on Wikidata
Coinage metals and alloys
Judea (Roman province)
Jewish Ptolemaic history
Ancient Jewish Persian history
Bar Kokhba revolt
Bar Kokhba hiding complexes | Khirbet Almit | [
"Chemistry"
] | 443 | [
"Alloys",
"Coinage metals and alloys"
] |
53,288,998 | https://en.wikipedia.org/wiki/Ofranergene%20obadenovec | Ofranergene obadenovec, also known as VB-111, is an anti-angiogenic gene therapy.
The vector is a non-replicating adenovirus 5. The payload is a chimeric gene encoding a fusion protein that combines the extracellular and intramembrane domains of the human TNF receptor 1 and the intracellular domain of the Fas receptor, under the control of a modified version of the murine promoter for endothelin-1, which is called PPE-1. PPE-1 drives tissues specific expression and also has a hypoxia responsive element. The FasR part of the payload is intended to drive cell death in the endothelium of blood vessels where the chimeric protein is expressed; the TNF-R1 part is intended to provide some tumor specificity.
Phase I trial results were presented in 2010 and as of 2011 Phase II trials in metastatic thyroid cancer had been started.
It was granted fast track designation and orphan drug status by the FDA in 2013 for treatment of glioblastoma multiforme.
It is under development by an Israeli company called Vascular Biogenics, also called VBL Therapeutics. The company was founded in 2000 by Dror Harats and Jacob George; it tried to hold an IPO on NASDAQ under the Jobs Act in August 2014, but the offering failed and was withdrawn after the stock had traded for six days. The company made a successful offering in September 2014 and raised $40 million.
References
Experimental cancer drugs
Angiogenesis inhibitors | Ofranergene obadenovec | [
"Biology"
] | 319 | [
"Angiogenesis",
"Angiogenesis inhibitors"
] |
53,289,561 | https://en.wikipedia.org/wiki/Bat%20flight | Bats are the only mammal capable of true flight. Bats use flight for capturing prey, breeding, avoiding predators, and long-distance migration. Bat wing morphology is often highly specialized to the needs of the species.
Evolution
Charles Darwin foresaw an issue with his theory of evolution by natural selection in the evolution of complex traits such as eyes or "the structure and habits of a bat." Indeed, the oldest bat fossils are very similar in wing morphology to the bats of today, despite living and dying 52.5 million years ago. Onychonycteris finneyi, the earliest known bat, already possessed powered flight. O. finneyi likely had an undulating flight style that alternated periods of fluttering with gliding. Evidence for this lies in the broad and short nature of O. finneyi wing morphology, which would have made it difficult to efficiently maneuver in the air or sustain flight. Additionally claws were seen on the ends of their forelimb digits (which have since disappeared in modern-day bats) giving evidence that O. finneyi was a skilled climber. The common ancestor of all bats is hypothesized to have been an arboreal quadruped of the northern hemisphere. This ancestor is predicted to have lived 64 million years ago at the border of the Cretaceous and Paleogene, based on molecular and paleontological data. There is a gap in the fossil record, and no transitional fossils exist from this quadrupedal ancestor to the appearance of the modern bat. It is unclear how long the transition from quadrupedalism to powered flight took. Based on a phylogenetic analysis of wing aerodynamics, the ancestral Chiropteran had wings with a low aspect ratio and rounded wingtips; this indicates it had slow but maneuverable and agile flight. After evolving powered flight, bats underwent massive adaptive radiation, becoming the second-most speciose mammal order, after rodents.
A 2011 study hypothesized that, rather than having evolved from gliders, the ancestors of bats were flutterers, although the researchers did not find any actual evidence for this theory. A 2020 study proposed that flight in bats might have originated independently at least three times, in the groups Yangochiroptera, Pteropodidae and Rhinolophoidea. A response paper rejected this hypothesis based on paleontological and developmental data. Stem-bats such as Onychonycteris and Icaronycteris were already capable of flying and the latter was a laryngeal echolocator. Contrary to the hypothesis of multiple flight origins, which assumes a bat ancestor with only handwings and no plagiopatagia, embryonic development shows the plagiopatagium appearing before the dactyloptagium. A model was used to test the viability of a handwings-only glider and found it ineffective as an actual gliding animal.
The expansion of the long bones in bat wings is at least partly attributed to paired-box (Pax) homeodomain transcription factor, PRX1. It is believed that changes in the PRX1 enhancer along with other molecular factors lead to the morphological separation of bats from their ancestors. Up-regulation of the bone morphogenetic protein (BMP) signaling pathway is also crucial in developmental and evolutionary elongation of bat forelimb digits.FGF10 signaling is also likely required for the development of bat wing membrane and muscles.
To make powered flight possible, bats had to evolve several features. Bat flight necessitated the increase of membrane surface area between the digits of the forelimbs, between the forelimbs and hindlimbs, and between the hindlimbs. Bats also had to evolve a thinner cortical bone to reduce torsional stresses produced by propulsive downstroke movements. Bats had to reroute innervation to their wing muscles to allow for control of powered flight. The strength and mass of forelimb musculature also had to be increased to allow powerful upstrokes and downstrokes. To provide sufficient oxygen supply to its body, bats also had to make several metabolic adaptations to provide for the increased energy cost of flight including high metabolic rate, increased lung capacity, and aerobic respiration.
Bats are the only mammals specialized for flight for a few reasons. They have specialized forelimbs, membranes, large pectoral muscles and large back muscles used for powering their wingbeats in flight. Both of these muscle groups are similar in appearance among vertebrates. However, bats have a unique muscle group known as the occipito-pollicalis, a necessary muscle group for mammalian flight. These muscle groups act to power flight and utilize the plagiopatagium which is the skin overlapping the forelimb, similar to the skin on species of flying squirrels. The skin located on the bat wing is called the patagium. It is composed of elastin fibers along with connective tissue, and provides durability and flexibility for the bat to lift itself easily.
Wing shape
Wing chord
The chord length of a bat wing is the distance from the leading edge to the trailing edge measured parallel to the direction of flight. The mean chord length is a standardized measure which captures a representative chord length over a whole flap cycle. Given wing area S, and wingspan b, the mean chord can be calculated by,
Aspect ratio
Aspect ratio has been calculated with different definitions. The two methods outlined here give different, non-comparable values. The first method of calculation uses the wingspan b, and the wing area S, and is given by,
Using this definition, typical values of aspect ratio fall between 5 and 11 depending on the wing morphology of a given species. Faster flight speed is significantly correlated with higher aspect ratios. Higher aspect ratios decrease the energetic costs of flight, which is beneficial to migratory species.
Another way to calculate the wing aspect ratio is by taking the length of the wrist to the tip of the third finger, adding the length of the forearm, and then dividing that total by the distance from the wrist to the fifth finger.
Wing loading
Wing loading is the weight of the bat divided by the wing area and is expressed using the unit N/m2 (newtons per square metre). Given a bat of mass m, the wing loading Q is,
For bats, wing loading values typically range from 4 to 35 N/m2 depending on the bat species. Mass loading differs only by a constant g, and is expressed in kg/m2.
In a meta analysis covering 257 species of bats, higher relative wing loading values were observed in bats which fly at higher velocities, while lower wing loading values were correlated with improved flight maneuverability. Additionally, bats with lower wing loading were seen to have better mass-carrying ability, and were able carry larger prey while flying.
Wingtips
Bats with larger wingtips have slower flight speeds. Wings with rounded tips have lower aspect ratios, and are associated with slower, more maneuverable flight.
Wing morphology as it relates to ecology
Fast hawking
Bats that consume insects by hawking (aerial pursuit and capture) must be able to travel at fast speeds, and must employ a high level of maneuverability. Morphological adaptations that favor this style of flight include high wing loading, long and pointed wingtips, and wings with high aspect ratios. The bat family Molossidae is considered highly specialized at hawking, with unusually high aspect ratios and wing loading. These traits make them capable of incredibly fast speeds. Mexican free-tailed bats are thought to be the fastest mammal on earth, capable of horizontal flight speeds over a level surface up to 160 km/h (100 mph).
Gleaning
Bats that glean insects capture stationary prey on a solid substrate. This foraging method requires bats to hover above the substrate and listen for insect noises. Short, rounded wingtips in gleaning bats may be advantageous to allow maneuverability of flight in cluttered airspace. Pointed wingtips may be detrimental to a bat's ability to glean insects.
Trawling
Bats with this foraging style pluck insects off the surface of a body of water. Piscivores employ the same flight style to catch fish just below the water's surface. Trawling bats travel at slower speeds, which means that they require low wing loading.
Frugivory
Frugivores have below-average aspect ratios. Fruit-eating bats have variable wing-loading, which corresponds to vertical stratification of rain forests. Fruit-eating bats that travel below the canopy have higher wing-loading; bats that travel above the canopy have intermediate wing-loading; bats that travel in the understory have low wing-loading. This pattern of decreasing wing-loading as airspace becomes more cluttered is consistent with data that suggest that lower wing-loading is associated with greater maneuverability.
Nectarivory
Nectarivores, like gleaners, will frequently employ hovering during foraging. Hovering nectarivores are more likely to have rounded wingtips, which aids in maneuverability. Nectarivores that land on the flower before feeding have worse maneuverability. Nectarivores in general have lower aspect ratios, which makes them more suited to flight in a cluttered environment. Nectarivores that migrate to seasonal food resources, such as the genus Leptonycteris, have lower wing-loading than nectarivorous species with small home ranges.
Carnivory
Bats that consume non-insect animal prey are benefited by low wing-loading, which allows them to lift and carry larger prey items. This increased capacity for lift even allows them to take flight from the ground while carrying a prey item that is half of their body weight.
Sanguinivory
The three species of sanguinivorous bats belong to the subfamily Desmodontinae. These bats are characterized by relatively high wing-loading and short or average wingspans. The high wing-loading allows them faster flight speeds, which is advantageous when they have to commute long distances from their roosts to find prey. The common vampire bat has an average aspect ratio and very short, slightly rounded wingtips. The hairy-legged vampire bat has the lowest aspect ratio of the three species; it also has relatively long and rounded wingtips. Hairy-legged vampire bats are more adapted to maneuverable flights than the other two species. The white-winged vampire bat has the highest aspect ratio of the three species, which means it is most adapted to long flights.
References
Animal flight
Morphology (biology) | Bat flight | [
"Biology"
] | 2,144 | [
"Morphology (biology)"
] |
53,290,169 | https://en.wikipedia.org/wiki/CFexpress | CFexpress is a standard for removable media cards proposed by the CompactFlash Association (CFA). The standard uses the NVM Express protocol over a PCIe 3.0 interface with 1 to 4 lanes where 1 GB/s data can be provided per lane. There are multiple form factors that feature different PCIe lane counts. One of the goals is to unify the ecosystem of removable storage by being compatible with standards already widely adopted, such as PCIe and NVMe. There already is a wide range of controllers, software and devices that use these standards, accelerating adoption.
History
On 7 September 2016, the CompactFlash Association announced CFexpress. The specification would be based on the PCI Express interface and NVM Express protocol.
On 18 April 2017 the CompactFlash Association published the CFexpress 1.0 specification. Version 1.0 will use the XQD form-factor (38.5 mm × 29.8 mm × 3.8 mm) with two PCIe 3.0 lanes for speeds up to 2 GB/s. NVMe 1.2 is used for low-latency access, low overhead and highly parallel access.
On 13 June 2017, Delkin introduced the first CFexpress cards based on the CFexpress 1.0 specification. In February 2018, they released benchmarks, with sample units introduced in the second quarter of 2018, and production scheduled for the third quarter.
The CFexpress 2.0 standard was announced on 28 February 2019. It features two new card formats ("type A", one lane, more compact and "type C", four lanes, bigger and thicker, up to 4 GB/s), with the existing cards designated as "type B". The NVM Express protocol was upgraded to 1.3.
CFexpress 2.0 type B Gen4 Cards are basically already available in the form of the Seagate Storage Expansion Card for Xbox Series X and Xbox Series S, which are mechanically incompatible to most slots because of their lengthened housing.
The CFexpress 4.0 standard was announced on 28 August 2023. CFexpress 4.0 supports up to four PCIe 4.0 lanes, 2 GB/s per lane. The NVM Express protocol was upgraded to 1.4c.
Comparison
Form factors
CFexpress supports the following card sizes. The second column lists the oldest CFexpress version
that includes the form factor.
The larger form factors have more electrical contacts, allowing more PCIe lanes to be used.
Form factor B has the same size and contacts as an XQD card, allowing a single card slot to accept both XQD and CFexpress-B cards.
Compatible devices
A variety of memory card readers and memory cards were published.
Cards
Delkin
On 13 June 2017, Delkin introduced the first CFexpress cards, which were on the CFexpress 1.0 specification. The cards have a XQD form factor and use two PCIe 3.0 lanes. They come in 32 GB, 64 GB, 128 GB and 256 GB capacities.
More details on Delkin's CFexpress cards were revealed in February 2018. The cards should be able to be read from and written to with respectively up to 1.6 GB/s and up to 1.0 GB/s benchmarked with CrystalDiskMark 5.2.1. Sample units will be available in Q2 2018 and production is scheduled for Q3 2018.
Delkin's 512 GB Power CFexpress Type B card was reviewed along with several others in the early fall of 2020. Camnostic.com rated it the recommended buy due to generally doing well in its tests, but also because it was the cheaper of the alternatives. The article mentioned a firmware upgrade to address compatibility with the Canon EOS R5 camera in late September 2020.
ProGrade Digital
ProGrade Digital announced it would begin production and sale of CFexpress cards in 2018 with the Type-B form-factor (the same as XQD).
The 1 TB CFexpress card that ProGrade Digital showed at the Spring NAB show in 2018 demonstrated 1,400 Mbyte/sec read speed and over 700 Mbyte/sec burst write speed. This demonstration was performed using a Thunderbolt 3 CFexpress/XQD reader on a MacBook Pro computer.
Apacer
On 11 December 2018, Apacer announced its first CFexpress card, the PV130-CFX.
Wise Advanced
On 7 April 2019, Wise Advanced announced it was producing CFexpress cards with 512 GB, 256 GB, and 128 GB capacities, as well as a CFexpress Card Reader, all using CFexpress Type B.
Readers
CFexpress Type A
Sony MRW-G2
CFexpress Type B
BLACKJET TX-1CXQ
Sony MRW-G1. Compatible with both XQD and CFexpress Type B cards.
Delkin CF Express Reader (DDREADER-54)
SanDisk Professional PRO-READER CFexpress
Angelbird CFexpress Card Reader MK2 | Type B
Lexar Professional CFexpress Type B USB 3.1 Reader
Lexar Professional CFexpress Type B USB 3.2 Gen 2×2 Reader
Parts
On October 2, 2017, Rego Electronics announced CFexpress host connectors and card cardkits, parts that manufacturers can use for their CFexpress devices and cards.
Client devices
As of October 2017, there were no CFexpress client devices released. However, in late October 2017 a Lexar employee stated to Nikon Rumors:CFExpress is essentially the next revision of XQD, and there should be full backward compatibility with XQD, and that getting D4/D5/500/D850’s to work with CFE cards should be a simple software patch.
On 23 August 2018, Nikon announced their new mirrorless cameras, the Z6 and Z7. At launch they only supported XQD cards, but a later firmware update enabled support for CFexpress. On 13 February 2019, Nikon further confirmed that CFexpress support via a firmware update will also be coming to the D5, D850 and D500. On 16 December 2019, Nikon released firmware version 2.20 for the Z6 and Z7, adding support for CFExpress. In December 2020, Nikon released firmware version 1.20 for the Nikon D850 DSLR that added support from CFexpress-B in the camera's XQD slot.
On 28 August 2018, Phase One announced the XF IQ4 camera system (three bodies). Like the Nikon cameras, future support for CFexpress was added in a later firmware update.
On 24 October 2019, Canon announced the development of the EOS-1D X Mark III with dual CFexpress slots. The camera was officially released on 6 January 2020, with availability set for February.
On 12 February 2020, Nikon announced the Nikon D6, which uses dual CFexpress slots.
On 20 April 2020, Canon announced that the EOS R5, a hybrid mirrorless camera, will support CFexpress and SD UHS-II.
On 28 July 2020, Sony announced the α7S III, a mirrorless camera that will support dual CFexpress Type A and SD cards.
On 26 January 2021, Sony announced the α1, a mirrorless camera that will support dual CFexpress Type A and SD cards.
On 23 February 2021, Sony announced the FX3, a mirrorless camera that will support dual CFexpress Type A and SD cards.
On 14 September 2021, Canon announced the EOS R3, a mirrorless camera which has one CF Express Type B slot and one SD format slot.
On November 10, 2020, Microsoft launched the Xbox Series X and Series S with a slot for semi-proprietary Expansion Cards based on a CFexpress Type B form factor. These Cards only support PCIe Gen4.
On 21 October 2021, Sony announced the α7 IV, a mirrorless camera that will support single CFexpress Type A and SD cards.
On 28 October 2021, Nikon announced the Nikon Z 9 flagship mirrorless camera, which uses dual CFexpress Type B slots.
See also
CompactFlash
Memory cards
PCI Express
NVM Express
XQD card
SD Express
References
Computer-related introductions in 2016
Solid-state computer storage media
Computer standards | CFexpress | [
"Technology"
] | 1,742 | [
"Computer standards"
] |
53,290,292 | https://en.wikipedia.org/wiki/Museum%20of%20Space%20Exploration | The Museum of Space Exploration is a museum in Ukraine that is located in a former church. It is one of over 30 museums in the "museum city" of Pereiaslav. The church was originally built in 1891, moved in 1971 when the region it was built in was flooded, and reconstructed in 1973.
Location
The museum is located in the "museum city" of Pereiaslav, Ukraine, where it is one of over 30 museums as part of the "Museum of Folk Architecture and Life of the Middle Dnieper National Historical-Ethnographic Reserve".
Church
The building used for the museum was originally a wooden village church named after Saint Paraskeva. It was originally built in 1891. When the region that the church was originally located in was flooded in 1971, the church was moved and was reconstructed in 1973.
The church has a crucifix layout, with a bell tower made with pine scaffold. It has a porch on three sides; the one on the fourth side was lost when the museum was relocated.
Museum
The museum opened in the hall of the relocated church in 1979. It has memorial rooms that recreate the times of Sergei Korolev and Alexander Ishlinsky, as well as an RD-219 rocket engine, a Minsk-32 computer system, a Foucault pendulum, Devices used on space vehicles, and an SK-II Space suit from Soyuz 23. It also has displays of photos of the moon passing the Earth, as well as from Mars 5, Mars 6 and Venera 9.
References
Museums in Kyiv Oblast
Space exploration
Aerospace museums in Ukraine | Museum of Space Exploration | [
"Astronomy"
] | 325 | [
"Space exploration",
"Outer space"
] |
53,290,451 | https://en.wikipedia.org/wiki/NBA%20InfoCenter | NBA InfoCenter is a professional social media outlet that reports news, trades and scores for the National Basketball Association. Since January 2016, NBA InfoCenter has given NBA fans the coverage of news on social media app Instagram, and has since expanded to Snapchat and Facebook. On December 4, 2016, the account reached 10,000 followers on Instagram
References
SMMFlare
National Basketball Association
Social media | NBA InfoCenter | [
"Technology"
] | 85 | [
"Computing and society",
"Social media"
] |
53,292,889 | https://en.wikipedia.org/wiki/Applications%20of%203D%20printing | In recent years, 3D printing has developed significantly and can now perform crucial roles in many applications, with the most common applications being manufacturing, medicine, architecture, custom art and design, and can vary from fully functional to purely aesthetic applications.
3D printing processes are finally catching up to their full potential, and are currently being used in manufacturing and medical industries, as well as by sociocultural sectors which facilitate 3D printing for commercial purposes. There has been a lot of hype in the last decade when referring to the possibilities we can achieve by adopting 3D printing as one of the main manufacturing technologies. Utilizing this technology would replace traditional methods that can be costly and time consuming. There have been case studies outlining how the customization abilities of 3D printing through modifiable files have been beneficial for cost and time effectiveness in a healthcare applications.
There are different types of 3D printing such as fused filament fabrication (FFF), stereolithography (SLA), selective laser sintering (SLS), polyjet printing, Multi-Jet Fusion (MJF), Direct Metal Laser Sintering (DMLS), and Electron Beam Melting (EBM).
For a long time, the issue with 3D printing was that it has demanded very high entry costs, which does not allow profitable implementation to mass-manufacturers when compared to standard processes. However, recent market trends spotted have found that this is finally changing. As the market for 3D printing has shown some of the quickest growth within the manufacturing industry in recent years. The applications of 3D printing are vast due to the ability to print complex pieces with a use of a wide range of materials. Materials can range from plastic and polymers as thermoplastic filaments, to resins, and even stem cells.
Manufacturing applications
AM technologies found applications starting in the 1980s in product development, data visualization, rapid prototyping, and specialized manufacturing. Their expansion into production (job production, mass production, and distributed manufacturing) has been under development in the decades since. Industrial production roles within the metalworking industries achieved significant scale for the first time in the early 2010s. Since the start of the 21st century there has been a large growth in the sales of AM machines, and their price has dropped substantially. According to Wohlers Associates, a consultancy, the market for 3D printers and services was worth $2.2 billion worldwide in 2012, up 29% from 2011. McKinsey predicts that additive manufacturing could have an economic impact of $550 billion annually by 2025. There are many applications for AM technologies, including architecture, construction (AEC), industrial design, automotive, aerospace, military, engineering, dental and medical industries, biotech (human tissue replacement), fashion, footwear, jewelry, eyewear, education, geographic information systems, food, and many other fields.
Additive manufacturing's earliest applications have been on the toolroom end of the manufacturing spectrum. For example, rapid prototyping was one of the earliest additive variants, and its mission was to reduce the lead time and cost of developing prototypes of new parts and devices, which was earlier only done with subtractive toolroom methods such as CNC milling and turning, and precision grinding, far more accurate than 3D printing with accuracy down to 0.00005" and creating better quality parts faster, but sometimes too expensive for low accuracy prototype parts. With technological advances in additive manufacturing, however, and the dissemination of those advances into the business world, additive methods are moving ever further into the production end of manufacturing in creative and sometimes unexpected ways. Parts that were formerly the sole province of subtractive methods can now in some cases be made more profitably via additive ones. In addition, new developments in RepRap technology allow the same device to perform both additive and subtractive manufacturing by swapping magnetic-mounted tool heads.
Cloud-based additive manufacturing
Additive manufacturing in combination with cloud computing technologies allows decentralized and geographically independent distributed production. Cloud-based additive manufacturing refers to a service-oriented networked manufacturing model in which service consumers are able to build parts through Infrastructure-as-a-Service (IaaS), Platform-as-a-Service (PaaS), Hardware-as-a-Service (HaaS), and Software-as-a-Service (SaaS). Distributed manufacturing as such is carried out by some enterprises; there is also a services like 3D Hubs that put people needing 3D printing in contact with owners of printers.
Some companies offer online 3D printing services to both commercial and private customers, working from 3D designs uploaded to the company website. 3D-printed designs are either shipped to the customer or picked up from the service provider.
There are many open source websites that have downloadable STL files which are able to be modified or printed as is. Files ranging from functional tools to aesthetic figurines are available to the general public. Open source files can be beneficial for the user as the printed object can be more cost effective than commercial counterparts.
Mass customization
Companies have created services where consumers can customize objects using simplified web based customization software, and order the resulting items as 3D printed unique objects. This now allows consumers to create things like custom cases for their mobile phones or scans of their brains. Nokia has released the 3D designs for its case so that owners can customize their own case and have it 3D printed.
Rapid manufacturing
Advances in RP technology have introduced materials that are appropriate for final manufacture, which has in turn introduced the possibility of directly manufacturing finished components. One advantage of 3D printing for rapid manufacturing lies in the relatively quick and inexpensive production of small numbers of parts.
Rapid manufacturing is a new method of manufacturing and many of its processes remain unproven. 3D printing is now entering the field of rapid manufacturing and was identified as a "next level" technology by many experts in a 2009 report. One of the most promising processes looks to be the adaptation of selective laser sintering (SLS), or direct metal laser sintering (DMLS) some of the better-established rapid prototyping methods. , however, these techniques were still very much in their infancy, with many obstacles to be overcome before RM could be considered a realistic manufacturing method.
There have been patent lawsuits concerning 3-D printing for manufacturing.
Rapid prototyping
Industrial 3D printers have existed since the early 1980s and have been used extensively for rapid prototyping and research purposes. These are generally larger machines that use proprietary powdered metals, casting media (e.g. sand), plastics, paper or cartridges, and are used for rapid prototyping by universities and commercial companies.
Research
3D printing can be particularly useful in research labs due to its ability to make specialized, bespoke geometries. In 2012 a proof of principle project at the University of Glasgow, UK, showed that it is possible to use 3D printing techniques to assist in the production of chemical compounds. They first printed chemical reaction vessels, then used the printer to deposit reactants into them. They have produced new compounds to verify the validity of the process, but have not pursued anything with a particular application.
Usually, the FDM process is used to print hollow reaction vessels or microreactors. If the 3D print is performed within an inert gas atmosphere, the reaction vessels can be filled with highly reactive substances during the print. The 3D printed objects are air- and watertight for several weeks. By the print of reaction vessels in the geometry of common cuvettes or measurement tubes, routine analytical measurements such as UV/VIS-, IR- and NMR-spectroscopy can be performed directly in the 3D printed vessel.
In addition, 3D printing has been used in research labs as alternative method to manufacture components for use in experiments, such as magnetic shielding and vacuum components with demonstrated performance comparable to traditionally produced parts.
Food
Additive manufacturing of food is being developed by squeezing out food, layer by layer, into three-dimensional objects. A large variety of foods are appropriate candidates, such as chocolate and candy, and flat foods such as crackers, pasta, and pizza. NASA has considered the versatility of the concept, awarding a contract to the Systems and Materials Research Consultancy to study the feasibility of printing food in space. NASA is also looking into the technology in order to create 3D printed food to limit food waste and to make food that are designed to fit an astronaut's dietary needs. A food-tech startup Novameat from Barcelona 3D-printed a steak from peas, rice, seaweed, and some other ingredients that were laid down criss-cross, imitating the intracellular proteins. One of the problems with food printing is the nature of the texture of a food. For example, foods that are not strong enough to be filed are not appropriate for 3D printing.
Agile tooling
Agile tooling is the process of using modular means to design tooling that is produced by additive manufacturing or 3D printing methods to enable quick prototyping and responses to tooling and fixture needs. Agile tooling uses a cost-effective and high-quality method to quickly respond to customer and market needs. It can be used in hydro-forming, stamping, injection molding and other manufacturing processes.
Medical applications
Surgical uses of 3D printing-centric therapies have a history beginning in the mid-1990s with anatomical modeling for bony reconstructive surgery planning. By practicing on a tactile model before surgery, surgeons were more prepared and patients received better care. Patient-matched implants were a natural extension of this work, leading to truly personalized implants that fit one unique individual. Virtual planning of surgery and guidance using 3D printed, personalized instruments have been applied to many areas of surgery including total joint replacement and craniomaxillofacial reconstruction with great success. Further study of the use of models for planning heart and solid organ surgery has led to increased use in these areas. Hospital-based 3D printing is now of great interest and many institutions are pursuing adding this specialty within individual radiology departments. The technology is being used to create unique, patient-matched devices for rare illnesses. One example of this is the bioresorbable trachial splint to treat newborns with tracheobronchomalacia developed at the University of Michigan. Several devices manufacturers have also begun using 3D printing for patient-matched surgical guides (polymers). The use of additive manufacturing for serialized production of orthopedic implants (metals) is also increasing due to the ability to efficiently create porous surface structures that facilitate osseointegration. Printed casts for broken bones can be custom-fitted and open, letting the wearer scratch any itches, wash and ventilate the damaged area. They can also be recycled.
Fused filament fabrication (FFF) has been used to create microstructures with a three-dimensional internal geometry. Sacrificial structures or additional support materials are not needed. Structure using polylactic acid (PLA) can have fully controllable porosity in the range 20%–60%. Such scaffolds could serve as biomedical templates for cell culturing, or biodegradable implants for tissue engineering.
3D printing has been used to print patient-specific implant and device for medical use. Successful operations include a titanium pelvis implanted into a British patient, titanium lower jaw transplanted to a Dutch patient, and a plastic tracheal splint for an American infant. The hearing aid and dental industries are expected to be the biggest areas of future development using custom 3D printing technology. In March 2014, surgeons in Swansea used 3D printed parts to rebuild the face of a motorcyclist who had been seriously injured in a road accident. Research is also being conducted on methods to bio-print replacements for lost tissue due to arthritis and cancer .
3D printing technology can now be used to make exact replicas of organs. The printer uses images from patients' MRI or CT scan images as a template and lays down layers of rubber or plastic. These models can be used to plan difficult operations, as was the case in May 2018, when surgeons used a 3D printed replica of a kidney to practice a kidney transplant on a three-year-old boy.
Thermal degradation during 3D printing of resorbable polymers, same as in surgical sutures, has been studied, and parameters can be adjusted to minimize the degradation during processing. Soft pliable scaffold structures for cell cultures can be printed.
In 3D printing, computer-simulated microstructures are commonly used to fabricate objects with spatially varying properties. This is achieved by dividing the volume of the desired object into smaller subcells using computer aided simulation tools and then filling these cells with appropriate microstructures during fabrication. Several different candidate structures with similar behaviours are checked against each other and the object is fabricated when an optimal set of structures are found. Advanced topology optimization methods are used to ensure the compatibility of structures in adjacent cells. This flexible approach to 3D fabrication is widely used across various disciplines from biomedical sciences where they are used to create complex bone structures and human tissue to robotics where they are used in the creation of soft robots with movable parts. 3D printing also finds its uses more and more in design and fabrication of laboratory apparatuses.
3D printing technology can also be used to produce personal protective equipment, also known as PPE, is worn by medical and laboratory professionals to protect themselves from infection when they are treating patients. Examples of PPE include face masks, face shields, connectors, gowns, and goggles. The most popular forms of 3D printed PPE are face masks, face shields, and connectors.
Nowadays, Additive Manufacturing is also employed in the field of pharmaceutical sciences to create 3D printed medication. Different techniques of 3D printing (e.g. FDM, SLS, Inkjet Printing etc) are utilized according to their respective advantages and drawbacks for various applications regarding drug delivery.
Bio-printing
In 2006, researchers at Cornell University published some of the pioneer work in 3D printing for tissue fabrication, successfully printing hydrogel bio-inks. The work at Cornell was expanded using specialized bioprinters produced by Seraph Robotics, Inc., a university spin-out, which helped to catalyze a global interest in biomedical 3D printing research.
3D printing has been considered as a method of implanting stem cells capable of generating new tissues and organs in living humans. With their ability to transform into any other kind of cell in the human body, stem cells offer huge potential in 3D bioprinting. Professor Leroy Cronin of Glasgow University proposed in a 2012 TED Talk that it was possible to use chemical inks to print medicine. In 2015 the FDA approved Spritam ®, a 3D printed drug also known as levetiracetam. Currently, there are three methods of 3D printing that have been explored for the production of drug making: laser based writing systems, printing-based inkjet systems, and nozzle based systems.
, 3D bio-printing technology has been studied by biotechnology firms and academia for possible use in tissue engineering applications in which organs and body parts are built using inkjet techniques. In this process, layers of living cells are deposited onto a gel medium or sugar matrix and slowly built up to form three-dimensional structures including vascular systems. The first production system for 3D tissue printing was delivered in 2009, based on NovoGen bioprinting technology. Several terms have been used to refer to this field of research: organ printing, bio-printing, body part printing, and computer-aided tissue engineering, among others. The possibility of using 3D tissue printing to create soft tissue architectures for reconstructive surgery is also being explored.
In 2013, Chinese scientists began printing ears, livers and kidneys, with living tissue. Researchers in China have been able to successfully print human organs using specialized 3D bioprinters that use living cells instead of plastic . Researchers at Hangzhou Dianzi University designed the "3D bioprinter" dubbed the "Regenovo". Xu Mingen, Regenovo's developer, said that it can produce a miniature sample of liver tissue or ear cartilage in less than an hour, predicting that fully functional printed organs might take 10 to 20 years to develop.
Medical devices
On October 24, 2014, a five-year-old girl born without fully formed fingers on her left hand became the first child in the UK to have a prosthetic hand made with 3D printing technology. Her hand was designed by US-based e-NABLE, an open source design organisation which uses a network of volunteers to design and make prosthetics mainly for children. The prosthetic hand was based on a plaster cast made by her parents. A boy named Alex was also born with a missing arm from just above the elbow. The team was able to use 3D printing to upload an e-NABLE Myoelectric arm that runs off of servos and batteries that are actuated by the electromyography muscle. With the use of 3D printers, e-NABLE has so far distributed thousands of plastic hands to children. Another example is Open Bionics, a company that makes fully functional bionic arms through 3D printing technology. 3D printing allows Open Bionics to create personalized designs for their clients, as there can be different colours, textures, patterns, and even "Hero Arms" that emulate superheroes like Ironman or characters from Star Wars.
Printed prosthetics have been used in rehabilitation of crippled animals. In 2013, a 3D printed foot let a crippled duckling walk again. 3D printed hermit crab shells let hermit crabs inhabit a new style home. A prosthetic beak was another tool developed by the use of 3D printing to help aid a bald eagle named Beauty, whose beak was severely mutilated from a shot in the face. Since 2014, commercially available titanium knee implants made with 3D printer for dogs have been used to restore the animals' mobility. Over 10,000 dogs in Europe and the United States have been treated after only one year.
In February 2015, FDA approved the marketing of a surgical bolt which facilitates less-invasive foot surgery and eliminates the need to drill through bone. The 3D printed titanium device, 'FastForward Bone Tether Plate' is approved to use in correction surgery to treat bunion. In October 2015, the group of Professor Andreas Herrmann at the University of Groningen has developed the first 3D printable resins with antimicrobial properties. Employing stereolithography, quaternary ammonium groups are incorporated into dental appliances that kill bacteria on contact. This type of material can be further applied in medical devices and implants.
3D Printing has been especially beneficial for the creation of patient specific prosthetics for large or invasive surgeries. In a case study published in 2020 about the benefits of 3D printing for hip prostheses, three patients with acetabular defects needed revisions of total hip arthroplasty (THA). 3D printing was utilized to produce prostheses that were specific to each of the three patients and their complex bone defect, which resulted in better post procedure recovery and prognosis of the individual.
In a case study about the applications of 3D printing in occupational therapy, the aspect of customization and quick fabrication at a low cost is utilized in different tools such as customized scissor handles and bottle openers for someone with hand motor complications. Beverage holders, writing guides, grip strengtheners, and other occupational therapy items were designed, printed, and compared with commercially available counterparts in a cost analysis. It found that the 3D printed items were on average 10.5 times more cost effective than commercial alternatives.
3D printing for medical devices can range from human prosthetics applications, to animal prostheses, to medical machine tools: On June 6, 2011, the company Xilloc Medical together with researchers at the University of Hasselt, in Belgium had successfully printed a new jawbone for an 83-year-old Dutch woman from the province of Limburg. 3D printing has been used to produce prosthetic beaks for eagles, a Brazilian goose named Victoria, and a Costa Rican toucan called Grecia. In March 2020, the Isinnova company in Italy printed 100 respirator valves in 24 hours for a hospital that lacked them in the midst of the coronavirus outbreak. It's clear that 3D printing technology is beneficial in many areas of healthcare.
Pharmaceutical Formulations
In May 2015 the first formulation manufactured by 3D printing was produced. In August 2015 the FDA approved the first 3D printed tablet. Binder-jetting into a powder bed of the drug allows very porous tablets to be produced, which enables high drug doses in a single formulation that rapidly dissolves and is easily absorbed. This has been demonstrated for Spritam, a reformulation of levetiracetam for the treatment of epilepsy.
Additive Manufacturing has been increasingly utilized by scientists in the pharmaceutical field. However, after the first FDA approval of a 3D printed formulation, scientific interest for 3D applications in drug delivery grew even bigger. Research groups around the world are studying different ways of incorporating drugs within a 3D printed formulation, for example by incorporating poorly water-soluble drugs in self-emulsifying systems or emulsion gels. 3D printing technology allows scientists to develop formulations with a personalized approach, i.e. dosage forms tailored specifically to an individual patient. Moreover, according to the advantages of the diverse utilized techniques, formulations with various properties can be achieved. These may contain multiple drugs in a single dosage form, multi-compartmental designs, drug delivery systems with distinct release characteristics, etc. During the earlier years, researchers have mainly focused on the Fused Deposition Modelling (FDM) technique. Nowadays, other printing techniques such as Selective Laser Sintering (SLS), Stereolithography (SLA) and Semi-solid extrusion (SSE) are also gaining traction and are being used for pharmaceutical applications.
Industrial applications
Apparel
3D printing has entered the world of clothing with fashion designers experimenting with 3D-printed bikinis, shoes, and dresses. In commercial production, Nike used 3D printing to prototype and manufacture the 2012 Vapor Laser Talon football shoe for players of American football, and New Balance is 3D manufacturing custom-fit shoes for athletes.
3D printing has come to the point where companies are printing consumer grade eyewear with on-demand custom fit and styling (although they cannot print the lenses). On-demand customization of glasses is possible with rapid prototyping.
However, comments have been made in academic circles as to the potential limitation of the human acceptance of such mass customized apparel items due to the potential reduction of brand value communication.
In the world of high fashion courtiers such as Karl Lagerfeld designing for Chanel, Iris van Herpen and Noa Raviv working with technology from Stratasys, have employed and featured 3d printing in their collections. Selections from their lines and other working with 3d printing were showcased at
the 2016 Metropolitan Museum of Art Anna Wintour Costume Center, exhibition "Manus X Machina".
Vanessa Friedman, fashion director and chief fashion critic at The New York Times, says 3D printing will have a significant value for fashion companies down the road, especially if it transforms into a print-it-yourself tool for shoppers. "There's real sense that this is not going to happen anytime soon," she says, "but it will happen, and it will create dramatic change in how we think both about intellectual property and how things are in the supply chain". She adds: "Certainly some of the fabrications that brands can use will be dramatically changed by technology."
During the COVID-19 pandemic, the Ukrainian-American undergraduate Karina Popovich founded Markers for COVID-19 which used 3D printing to create face shields, face masks and other items of personal protective equipment.
Industrial art and jewelry
3D printing is used to manufacture moulds for making jewelry, and even the jewelry itself. 3D printing is becoming popular in the customisable gifts industry, with products such as personalized models of art and dolls, in many shapes: in metal or plastic, or as consumable art, such as 3D printed chocolate.
Transportation Industries
In cars, trucks, and aircraft, additive manufacturing is beginning to transform both unibody and fuselage design and production, and powertrain design and production. For example, General Electric uses high-end 3D printers to build parts for turbines. Many of these systems are used for rapid prototyping before mass production methods are employed.
In early 2014, Swedish supercar manufacturer Koenigsegg announced the One:1, a supercar that utilizes many components that were 3D printed. In the limited run of vehicles Koenigsegg produces, the One:1 has side-mirror internals, air ducts, titanium exhaust components, and complete turbocharger assemblies that were 3D printed as part of the manufacturing process.
Urbee is the name of the first car in the world car mounted using the technology 3D printing (its bodywork and car windows were "printed"). Created in 2010 through the partnership between the US engineering group Kor Ecologic and the company Stratasys (manufacturer of printers Stratasys 3D), it is a hybrid vehicle with futuristic look.
In 2014, Local Motors debuted Strati, a functioning vehicle that was entirely 3D Printed using ABS plastic and carbon fiber, except the powertrain. In 2015, the company produced another iteration known as the LM3D Swim that was 80 percent 3D-printed. In 2016, the company has used 3D printing in the creation of automotive parts, such ones used in Olli, a self-driving vehicle developed by the company.
In May 2015 Airbus announced that its new Airbus A350 XWB included over 1000 components manufactured by 3D printing.
3D printing is also being utilized by air forces to print spare parts for planes. In 2015, a Royal Air Force Eurofighter Typhoon fighter jet flew with printed parts. The United States Air Force has begun to work with 3D printers, and the Israeli Air Force has also purchased a 3D printer to print spare parts.
In 2017, GE Aviation revealed that it had used design for additive manufacturing to create a helicopter engine with 16 parts instead of 900, weighing 40% lighter and being 60% cheaper. This also led to a simplified supply chain with less support from outer suppliers, as many of the parts could be produced in-house.
Construction, home development
The use of 3D printing to produce scale models within architecture and construction has steadily increased in popularity as the cost of 3D printers has reduced. This has enabled faster turn around of such scale models and allowed a steady increase in the speed of production and the complexity of the objects being produced.
Construction 3D printing, the application of 3D printing to fabricate construction components or entire buildings has been in development since the mid-1990s, development of new technologies has steadily gained pace since 2012 and the sub-sector of 3D printing is beginning to mature.
Firearms
In 2012, the US-based group Defense Distributed disclosed plans to "design a working plastic gun that could be downloaded and reproduced by anybody with a 3D printer." Defense Distributed has also designed a 3D printable AR-15 type rifle lower receiver (capable of lasting more than 650 rounds) and a 30-round M16 magazine. The AR-15 has multiple receivers (both an upper and lower receiver), but the legally controlled part is the one that is serialized (the lower, in the AR-15's case). Soon after Defense Distributed succeeded in designing the first working blueprint to produce a plastic gun with a 3D printer in May 2013, the United States Department of State demanded that they remove the instructions from their website. After Defense Distributed released their plans, questions were raised regarding the effects that 3D printing and widespread consumer-level CNC machining may have on gun control effectiveness.
In 2014, a man from Japan became the first person in the world to be imprisoned for making 3D printed firearms. Yoshitomo Imura posted videos and blueprints of the gun online and was sentenced to jail for two years. Police found at least two guns in his household that were capable of firing bullets.
Computers and robots
3D printing can also be used to make laptops and other computers and cases. For example, Novena and VIA OpenBook standard laptop cases. I.e. a Novena motherboard can be bought and be used in a printed VIA OpenBook case.
Open-source robots are built using 3D printers. Double Robotics grant access to their technology (an open SDK). On the other hand, 3&DBot is an Arduino 3D printer-robot with wheels and ODOI is a 3D printed humanoid robot.
Soft sensors and actuators
3D printing has found its place in soft sensors and actuators manufacturing inspired by 4D printing concept. The majority of the conventional soft sensors and actuators are fabricated using multistep low yield processes entailing manual fabrication, post-processing/assembly, and lengthy iterations with less flexibility in customization and reproducibility of final products. 3D printing has been a game changer in these fields with introducing the custom geometrical, functional, and control properties to avoid the tedious and time-consuming aspects of the earlier fabrication processes.
Sociocultural applications
In 2005, a rapidly expanding hobbyist and home-use market was established with the inauguration of the open-source RepRap and Fab@Home projects. Virtually all home-use 3D printers released to-date have their technical roots in the ongoing RepRap Project and associated open-source software initiatives. In distributed manufacturing, one study has found that 3D printing could become a mass market product enabling consumers to save money associated with purchasing common household objects. For example, instead of going to a store to buy an object made in a factory by injection molding (such as a measuring cup or a funnel), a person might instead print it at home from a downloaded 3D model.
Art and jewellery
In 2005, academic journals began to report on the possible artistic applications of 3D printing technology, being used by artists such as Martin John Callanan at The Bartlett school of architecture. By 2007 the mass media followed with an article in the Wall Street Journal and Time magazine, listing a printed design among their 100 most influential designs of the year. During the 2011 London Design Festival, an installation, curated by Murray Moss and focused on 3D Printing, was held in the Victoria and Albert Museum (the V&A). The installation was called Industrial Revolution 2.0: How the Material World will Newly Materialize.
At the 3DPrintshow in London, which took place in November 2013 and 2014, the art sections had works made with 3D printed plastic and metal. Several artists such as Joshua Harker, Davide Prete, Sophie Kahn, Helena Lukasova, Foteini Setaki showed how 3D printing can modify aesthetic and art processes. In 2015, engineers and designers at MIT's Mediated Matter Group and Glass Lab created an additive 3D printer that prints with glass, called G3DP. The results can be structural as well as artistic. Transparent glass vessels printed on it are part of some museum collections.
The use of 3D scanning technologies allows the replication of real objects without the use of moulding techniques that in many cases can be more expensive, more difficult, or too invasive to be performed, particularly for precious artwork or delicate cultural heritage artifacts where direct contact with the moulding substances could harm the original object's surface.
3D selfies
A 3D photo booth such as the Fantasitron located at Madurodam, the miniature park, generates 3D selfie models from 2D pictures of customers. These selfies are often printed by dedicated 3D printing companies such as Shapeways. These models are also known as 3D portraits, 3D figurines or mini-me figurines.
Communication
Employing additive layer technology offered by 3D printing, Terahertz devices which act as waveguides, couplers and bends have been created. The complex shape of these devices could not be achieved using conventional fabrication techniques. Commercially available professional grade printer EDEN 260V was used to create structures with minimum feature size of 100 μm. The printed structures were later DC sputter coated with gold (or any other metal) to create a Terahertz Plasmonic Device.
In 2016 artist/scientist Janine Carr Created the first 3d printed vocal percussion (beatbox) as a waveform, with the ability to play the soundwave by laser, along with four vocalised emotions these were also playable by laser.
Domestic use
Some early consumer examples of 3d printing include the 64DD released in 1999 in Japan. As of 2012, domestic 3D printing was mainly practiced by hobbyists and enthusiasts. However, little was used for practical household applications, for example, ornamental objects. Some practical examples include a working clock and gears printed for home woodworking machines among other purposes. Web sites associated with home 3D printing tended to include backscratchers, coat hooks, door knobs, etc.
As of 2023 consumer 3D printing has become increasingly common, an estimated 85% of 3D printers sold now are of the personal/desktop markets. Now more than ever its increasingly common to see 3D printing utilized by at home DIY/maker communities as 3D printers have become significantly more affordable for consumer audiences in recent years.
The open source Fab@Home project has developed printers for general use. They have been used in research environments to produce chemical compounds with 3D printing technology, including new ones, initially without immediate application as proof of principle. The printer can print with anything that can be dispensed from a syringe as liquid or paste. The developers of the chemical application envisage both industrial and domestic use for this technology, including enabling users in remote locations to be able to produce their own medicine or household chemicals.
3D printing is now working its way into households, and more and more children are being introduced to the concept of 3D printing at earlier ages. The prospects of 3D printing are growing, and as more people have access to this new innovation, new uses in households will emerge.
The OpenReflex SLR film camera was developed for 3D printing as an open-source student project.
Education and research
3D printing, and open source 3D printers in particular, are the latest technology making inroads into the classroom. 3D printing allows students to create prototypes of items without the use of expensive tooling required in subtractive methods. Students design and produce actual models they can hold. The classroom environment allows students to learn and employ new applications for 3D printing. RepRaps, for example, have already been used for an educational mobile robotics platform.
Some authors have claimed that 3D printers offer an unprecedented "revolution" in STEM education. The evidence for such claims comes from both the low cost ability for rapid prototyping in the classroom by students, but also the fabrication of low-cost high-quality scientific equipment from open hardware designs forming open-source labs. Engineering and design principles are explored as well as architectural planning. Students recreate duplicates of museum items such as fossils and historical artifacts for study in the classroom without possibly damaging sensitive collections. Other students interested in graphic designing can construct models with complex working parts easily. 3D printing gives students a new perspective with topographic maps. Science students can study cross-sections of internal organs of the human body and other biological specimens. And chemistry students can explore 3D models of molecules and the relationship within chemical compounds. The true representation of exactly scaled bond length and bond angles in 3D printed molecular models can be used in organic chemistry lecture courses to explain molecular geometry and reactivity.
According to a recent paper by Kostakis et al., 3D printing and design can electrify various literacies and creative capacities of children in accordance with the spirit of the interconnected, information-based world.
Future applications for 3D printing might include creating open-source scientific equipment.
Environmental use
In Bahrain, large-scale 3D printing using a sandstone-like material has been used to create unique coral-shaped structures, which encourage coral polyps to colonize and regenerate damaged reefs. These structures have a much more natural shape than other structures used to create artificial reefs, and, unlike concrete, are neither acid nor alkaline with neutral pH.
Cultural heritage
In the last several years 3D printing has been intensively used by in the cultural heritage field for preservation, restoration and dissemination purposes. Many Europeans and North American Museums have purchased 3D printers and actively recreate missing pieces of their relics.
Scan the World is the largest archive of 3D printable objects of cultural significance from across the globe. Each object, originating from 3D scan data provided by their community, is optimised for 3D printing and free to download on MyMiniFactory. Through working alongside museums, such as The Victoria and Albert Museum and private collectors, the initiative serves as a platform for democratizing the art object.
The Metropolitan Museum of Art and the British Museum have started using their 3D printers to create museum souvenirs that are available in the museum shops. Other museums, like the National Museum of Military History and Varna Historical Museum, have gone further and sell through the online platform Threeding digital models of their artifacts, created using Artec 3D scanners, in 3D printing friendly file format, which everyone can 3D print at home.
Specialty materials
Consumer grade 3D printing has resulted in new materials that have been developed specifically for 3D printers. For example, filament materials have been developed to imitate wood in its appearance as well as its texture. Furthermore, new technologies, such as infusing carbon fiber into printable plastics, allowing for a stronger, lighter material. In addition to new structural materials that have been developed due to 3D printing, new technologies have allowed for patterns to be applied directly to 3D printed parts. Iron oxide-free Portland cement powder has been used to create architectural structures up to 9 feet in height.
See also
3D printing processes
3D printing
Construction 3D printing
Health and safety hazards of 3D printing
References
Sources
3D printing
Industrial design
Industrial processes | Applications of 3D printing | [
"Engineering"
] | 7,761 | [
"Industrial design",
"Design engineering",
"Design"
] |
53,293,034 | https://en.wikipedia.org/wiki/NGC%202357 | NGC 2357 is a spiral galaxy located in the constellation of Gemini. It was discovered by Édouard Stephan on 6 February 1885.
Supernovae
SN 2010bj, a Type II-P supernova, was detected in February 2010, and SN 2015I, a Type Ia supernova was detected in May 2015.
References
Unbarred spiral galaxies
Gemini (constellation)
2357
3782
20592
Discoveries by Édouard Stephan | NGC 2357 | [
"Astronomy"
] | 89 | [
"Gemini (constellation)",
"Constellations"
] |
53,293,378 | https://en.wikipedia.org/wiki/Position-specific%20isotope%20analysis | Position-specific isotope analysis, also called site-specific isotope analysis, is a branch of isotope analysis aimed at determining the isotopic composition of a particular atom position in a molecule. Isotopes are elemental variants with different numbers of neutrons in their nuclei, thereby having different atomic masses. Isotopes are found in varying natural abundances depending on the element; their abundances in specific compounds can vary from random distributions (i.e., stochastic distribution) due to environmental conditions that act on the mass variations differently. These differences in abundances are called "fractionations," which are characterized via stable isotope analysis.
Isotope abundances can vary across an entire substrate (i.e., “bulk” isotope variation), specific compounds within a substrate (i.e., compound-specific isotope variation), or across positions within specific molecules (i.e., position specific isotope variation). Isotope abundances can be measured in a variety of ways (e.g., isotope ratio mass spectrometry, laser spectrometry, NMR, ESI-MS). Early analyses varied in technique, but were commonly limited by their ability to only measure average isotope compositions over molecules or samples. While this allows isotope analysis of the bulk substrate, it eliminates the ability to distinguish variation between different sites of the same element within the molecule. The field of position-specific isotope biogeochemistry studies these intramolecular variations, known as “position-specific isotope” and “site-specific isotope” enrichments. It focuses on position-specific isotope fractionations in many contexts, development of technologies to measure these fractionations and the application of position-specific isotope enrichments to questions surrounding biogeochemistry, microbiology, enzymology, medicinal chemistry, and earth history.
Position-specific isotope enrichments can retain critical information about synthesis and source of the atoms in the molecule. Indeed, bulk isotope analysis averages site-specific isotope effects across the molecule, and so while all those values have an influence on the bulk value, signatures of specific processes may be diluted or indistinguishable. While the theory of position-specific isotope analysis has existed for decades, new technologies exist now to allow these methods to be much more common. The potential applications of this approach are widespread, such as understanding metabolism in biomolecules, environmental pollutants in air, inorganic reaction mechanisms, etc. Clumped isotope analysis, a subset of position-specific isotope analysis, has already proven useful in characterizing sources of methane, paleoenvironment, paleoaltimetry, among many other applications. More specific case studies of position-specific isotope fractionation are detailed below.
Theory
Stable isotopes do not decay, and the heavy and light isotope masses affect how they partition within the environment. Any deviation from a random distribution of the light and heavy isotopes within the environment is called fractionation, and consistent fractionations as a result of a particular process or reaction are called "isotope effects."
Isotope Effects
Isotope effects are recurring patterns in the partitioning of heavy and light isotopes across different chemical species or compounds, or between atomic sites within a molecule. These isotope effects can come about from a near infinite number of processes, but most of them can be narrowed down into two main categories, based on the nature of the chemical reaction creating or destroying the compound of interest:
(1) Kinetic isotope effects manifest in irreversible reactions, when one isotopologue is preferred in the transition state due to the lowest energy state. The preferred isotopologue will depend on whether the transition state of the molecule during a chemical reaction is more like the reactant or the product. Normal isotope effects are defined as those which partition the lighter isotope into the products of the reaction. Inverse isotope effects are less common as they preferentially partition the heavier isotope into the products.
(2) Equilibrium isotope effects manifest in reversible reactions, when molecules can exchange freely to reach the lowest possible energy state.
These variations can occur on a compound-specific level, but also on a position-specific level within a molecule. For instance, the carboxyl site of amino acids is exchangeable and therefore its carbon isotope signature can change over time and may not represent the original carbon source of the molecule.
Biological fractionation
Chemical reactions in biological processes are controlled by enzymes that catalyze the conversion of substrate to product. Since enzymes can alter the transition state structure for reactions, they also change kinetic and equilibrium isotope effects. Placed in the context of a metabolism, the expression of isotope effects on biomolecules is further controlled by branch points. Different pathways of biosynthesis will use different enzymes, yielding a range of position specific isotope enrichments. This variability allows position-specific isotope measurements to discern multiple biosynthetic pathways from the same metabolic product. Biogeochemists use position specific isotope enrichments from amino acids, lipids, and sugars in nature to interpret the relative importance of different metabolisms.
Mechanism
The position-specific isotope effect of an enzymatic reaction is expressed as the ratio of rate constants for a monoisotopic substrate and a substrate substituted with one rare isotope. For example, enzyme formate dehydrogenase catalyzes the reaction of formate and NAD+ to carbon dioxide and NADH. The hydrogen of formate is directly transferred to NAD+. This step has an isotope effect, because the rate of protium transfer from formate to NAD+ is nearly three times faster than the rate of the same reaction with a deuterium transfer. This is also an example of a primary isotope effect. A primary isotope effect is one in which the rare isotope is substituted where a bond is broken or formed. Secondary isotope effects occur on other positions in the molecule and are controlled by the molecular geometry of the transition state. These are generally considered to be negligible but do arise in certain cases, especially for hydrogen isotopes.
Unlike abiotic reactions, enzymatic reactions occur through a series of steps, including substrate-enzyme binding, conversion of substrate to product, and dissociation of enzyme-product complex. The observed isotope effect of an enzyme will be controlled by the rate limiting step in this mechanism. If the step that converts substrate to product is rate limiting, the enzyme will express its intrinsic isotope effect, that of the bond forming or breaking reaction.
Abiological fractionation
Like biotic molecules, position specific isotope enrichments in abiotic molecules can reflect the source of chemical precursors and synthesis pathways. The energy for abiotic reactions can come from many different sources, which will affect fractionation. For instance, metal catalysts can speed up abiotic reactions. Reactions can be slowed down or sped up by different temperature and pressure conditions, which will affect the equilibrium constant or activation energy of reversible and irreversible reactions, respectively.
For example, carbon in the interstellar medium and solar nebula partition into distinct states based on thermodynamic favorability. Measuring site-specific isotope enrichments of carbon from organic molecules extracted from carbonaceous chondrites can elucidate where each carbon atom comes from, and how organic molecules can be synthesized abiotically. More broadly, these isotope enrichments can provide information about physical processes in the region where the molecular precursors were formed, and where the molecule formed in the solar system (i.e., nucleosynthetic heterogeneity, mass independent fractionation, self-shielding, etc.).
Another example of distinct site-specific fractionations in abiotic molecules is Fischer-Tropsch-type synthesis, which is thought to produce abiogenic hydrocarbon chains. Through this reaction mechanism, site enrichments of carbon would deplete as carbon chain length increases, and be distinct from site-specific enrichments of hydrocarbons of biological origins.
Analysis
Substrates need to be prepared and analyzed in a specific way to elucidate site specific isotope enrichments. This requires clean separation of the compound of interest from the original sample, which can require a variety of different preparatory chemistries. Once isolated, position-specific isotope enrichments can be analyzed with a variety of instruments, which all have different advantages and provide varying degrees of precision.
Enzymatic Reaction
To measure the kinetic isotope effects of enzymatic reactions, biochemists perform in vitro experiments with enzymes and substrates. The goal of these experiments is to measure the difference in the enzymatic reaction rates for the monoisotopic substrate and the substrate with one rare isotope. There are two popularly used techniques in these experiments: Internal competition studies and direct comparison experiments. Both measure position-specific isotope effects.
Direct Comparison
Direct comparison experiments are primarily used for measuring hydrogen/deuterium isotope effects in enzymatic reactions. The monoisotopic substrate and a deuterated form of the substrate are separately exposed to the enzyme of interest over a range of concentrations. The Michaelis-Menten kinetic parameters for both substrates are determined and the position-specific isotope effect at the site of deuteration is expressed as the ratio of the monoisotopic rate constant over the rare isotope rate constant.
Internal Competition
For isotopes of elements like carbon and sulfur, the difference in kinetic parameters is too small, and the measurement precision too low, to measure an isotope effect by directly comparing the rates of the monoisotopic and rare isotope substrates. Instead, the two are mixed together using the natural abundance of stable isotopes in molecules. The enzyme is exposed to both isotopes simultaneously and its preference for the light isotope is analyzed by collecting the product of the reaction and measuring its isotope composition. For example, if an enzyme removes a carbon from a molecule by turning it into carbon dioxide, that carbon dioxide product can be collected and measured on an Isotope Ratio Mass Spectrometer for its carbon isotope composition. If the carbon dioxide has less 13C than the substrate mixture, the enzyme has preferentially reacted with the substrate that has a 12C at the site that is decarboxylated. In this way, internal competition experiments are also position-specific. If only the CO2 is measured, then only the isotope effect on the site of decarboxylation is recorded.
Chemical degradation
Before the advent of technologies that analyze whole molecules for their intramolecular isotopic structure, molecules were sequentially degraded and converted to CO2 and measured on an Isotope Ratio Mass Spectrometer, revealing position-specific 13C enrichments.
Ninhydrin Reaction
In 1961, Abelson and Hoering developed a technique for removing the carboxylic acid of amino acids using the ninhydrin reaction. This reaction converts the carboxylic acid to a molecule of CO2 which is measured via an Isotope Ratio Mass Spectrometer.
Ozonolysis Reaction
Lipids are of particular interest to stable isotope geochemists because they are preserved in rocks for millions of years. Monson & Hayes used ozonolysis to characterize the position-specific isotope abundances of unsaturated fatty acids, turning different carbon positions into carbon dioxide. Using this technique, they directly measured an isotopic pattern in fatty acids that had been predicted for years.
Preparatory Chemistry
Derivatization
In some cases, additional functional groups will need to be added to molecules to facilitate the other separation and analysis methods. Derivatization can change the properties of an analyte; for instance, it would make a polar and non-volatile compound non-polar and more volatile, which would be necessary for analysis in certain types of chromatography. It is important to note, however, that derivatization is not ideal for site-specific analyses as it adds additional elements that must be accounted for in analyses.
Chromatography
Chromatography facilitates separation of distinct molecules within a mixture based on their respective chemical properties, and how those properties interact with the substrate coating the chromatographic column. This separation can happen “on-line,” during the measurement itself, or prior to measurements to isolate a pure compound. Gas and liquid chromatography have distinct advantages, based on the molecules of interest. For example, aqueously soluble molecules are more easily separated with liquid chromatography, while volatile, nonpolar molecules like propane or ethane are separated with gas chromatography.
Instrumental Analysis
A variety of different instruments can be used to perform position-specific isotope analysis, and each have distinct advantages and drawbacks. Many of them require comparison the sample of interest to a standard of known isotopic composition; fractionation within the instrument and variation of instrumental conditions over time can affect accuracy of individual measurements if not standardized.
GC-IRMS and LC-MS
Initial measurements of position specific isotope enrichments were measured using isotope ratio mass spectrometry in which sites on a molecule were first degraded to , the was captured and purified, and then the CO2 was measured for its isotope composition on an Isotope Ratio Mass Spectrometer (IRMS). Py-GC-MS was also used in these experiments to degrade molecules even further and characterize their intramolecular isotopic distributions. Both GC-MS and LC-MS are capable of characterizing position specific isotope enrichments in isotopically labelled molecules. In these molecules, 13C is so abundant that it can be seen on a mass spectrometer with low sensitivity. The resolution of these instruments can distinguish two molecules with a 1 Dalton difference in their molecular masses; however, this difference could arise from the addition of many rare isotopes (17O, 13C, 2H, etc.). For this reason, mass spectrometers using quadrupoles or time-of-flight detection techniques cannot be used for measuring position-specific enrichments at natural abundances.
Spectroscopy
Laser spectroscopy can be used to measure isotope enrichments of gases in the environment. Laser spectroscopy takes advantage of the different vibrational frequencies of isotopologues which cause them to absorb different wavelengths of light. Transmission of light through the gaseous sample at a controlled temperature can be quantitatively converted into a statement about isotopic composition. For N2O, these measurements can determine the position specific isotope enrichments of (15N. These measurements are fast and can reach relatively good precision (1-10 per mille). It is used to characterize environmental gas fluxes, and effects on these fluxes. This method is limited to measurement and characterization of gases.
Nuclear magnetic resonance (NMR)
Nuclear magnetic resonance observes small differences in molecular reactions to oscillating magnetic fields. It is able to characterize atoms with active nuclides that have a non-zero nuclear spin (e.g., 13C, 1H, 17O 35Cl, 15N, 37Cl), which makes it particularly useful for identifying certain isotopes. In typical proton or 13C NMR, the chemical shifts of protiums (1H) and carbon-13 atoms within a molecule are measured, respectively, as they are excited by a magnetic field and then relax with a diagnostic resonance frequency. With site specific natural isotope fractionation (SNIF) NMR, the relaxation resonances of the deuterium and 13C atoms. NMR does not have the sensitivity to detect isotopologues with multiple rare isotopes. The only peaks that appear in a SNIF-NMR spectra are those of the isotopologues with a single rare isotope. Since the instrument is only measuring the resonances of the rare isotopes, each isotopologue will have one peak. For example, a molecule with six chemically unique carbon atoms will have six peaks in a 13C SNIF NMR spectrum. The site of 13C substitution can be determined by the chemical shift of each of the peaks. As a result, NMR is able to identify site specific isotope enrichments within molecules.
Orbitrap Mass Spectrometry
The Orbitrap is a high-resolution Fourier transform mass spectrometer that has recently been adapted to allow for site-specific analyses. Molecules introduced into the Orbitrap are fragmented, accelerated, and analyzed. Because the Orbitrap characterizes molecular masses by measuring oscillations at radio frequencies, it is able to reach very high levels of precision, depending on measurement method (i.e., down to 0.1 per mille for long integration times). It is significantly faster than site-specific isotope measurements that can be performed using NMR, and can measure molecules with different rare isotopes but the same nominal mass at natural abundances (unlike GC and LCMS). It is also widely generalizable to molecules that can be introduced via gas or liquid solvent. Resolution of the Orbitrap is such that nominal isobars (e.g., 2H versus 15N versus 13C enrichments) can be distinguished from one another, and so molecules do not need to be converted into a homogeneous substrate to facilitate isotope analysis. Like other isotope measurements, measurements of site-specific enrichments on the Orbitrap should be compared to a standard of known composition.
Case studies
To illustrate the utility of position-specific isotope enrichments, several case studies are described below in which scientists used position-specific isotope analyses to answer important questions about biochemistry, pollution, and climate.
Phosphoenolpyruvate carboxylase
Phosphoenolpyruvate carboxylase (PEPC) is an enzyme that combines bicarbonate and phosphoenolpyruvate (PEP) to form the four-carbon acid, oxaloacetate. It is an important enzyme in C4 photosynthesis and anaplerotic pathways. It is also responsible for the position-specific enrichment of oxaloacetate, due to the equilibrium isotope effect of converting the linear molecule CO2 into the trigonal planar molecule HCO3-, which partitions 13C into bicarbonate. Inside the PEPC enzyme, H12CO3- reacts 1.0022 times faster than H13CO3- so that PEPC has a 0.22% kinetic isotope effect. This is not enough to compensate for the 13C enrichment in bicarbonate. Thus, oxaloacetate is left with a 13C-enriched carbon at the C4 position. However, the C1 site experiences a small inverse secondary isotope effect due to its bonding environment in the transition state, leaving the C1 site of oxaloacetate enriched in 13C. In this way, PEPC simultaneously partitions 12C into the C4 site and 13C into the C1 site of oxaloacetate, an example of multiple position-specific isotope effects.
Amino acids
The first paper on site-specific enrichment used the ninhydrin reaction to cleave the carboxyl site off alpha-amino acids in photosynthetic organisms. The authors demonstrated an enriched carboxyl site relative to the bulk δ13C of the molecules, which they attribute to uptake of heavier CO2 through the Calvin cycle. A recent study applied similar theory to understand enrichments in methionine, which they suggested would be powerful in origin and synthesis studies.
Carbohydrates
In 2012, a team of scientists used NMR spectroscopy to measure all of the position-specific carbon isotope abundances of glucose and other sugars. It was shown that the isotope abundances are heterogeneous. Different portions of the sugar molecules are used for biosynthesis based on the metabolic pathway an organism uses. Therefore, any interpretations of position-specific isotopes of molecules downstream of glucose have to consider this intramolecular heterogeneity.
Glucose is the monomer of cellulose, the polymer that makes plants and trees rigid. After the advent of position-specific analyses of glucose, biogeochemists from Sweden looked the concentric tree rings of a Pinus nigra that recorded yearly growth between 1961 and 1995. They digested the cellulose down to its glucose units and used NMR spectroscopy to analyze its intramolecular isotopic patterns. They found correlations with position-specific isotope enrichments that were not apparent with whole molecule carbon isotope analysis of glucose. By measuring position-specific enrichments in the 6-carbon glucose molecule, they gathered six times more information from the same sample.
Fatty acids
The biosynthesis of fatty acids begins with acetyl-CoA precursors that are brought together to make long straight chain lipids. Acetyl-CoA is produced in aerobic organisms by pyruvate dehydrogenase, an enzyme that has been shown to express a large, 2.3% isotope effect on the C2 site of pyruvate and a small fractionation on the C3 site. These become the odd and even carbon positions of fatty acids respectively and in theory would result in a pattern of 13C depletions and enrichments at odd and even positions, respectively. In 1982, Monson and Hayes developed technology for measuring the position specific carbon isotope abundances of fatty acids. Their experiments on Escherichia coli revealed the predicted relative 13C enrichments at odd numbered carbon sites. However, this pattern was not found in Saccharomyces cerevisiae that were fed glucose. Instead, its fatty acids were 13C enriched at the odd positions. This has been interpreted as either a product of isotope effects during fatty acid degradation or the intramolecular isotopic heterogeneity of glucose that ultimately is reflected in the position-specific patterns of fatty acids.
Nitrous Oxide
Site specific isotope enrichments of N2O is measured in the environment to help disentangle microbial sources and sinks in the environment. Different isotopologues of N2O absorb light at different wavelengths. Laser spectroscopy converts these differences as it scans across wavelengths to measure the abundance of 14N-15N-16O vs. 15N-14N-16O, a distinction that is impossible on other instruments. These measurements have achieved very high precision, down to 0.2 per mille.
Environmental pollutants
Position-specific isotopes can be used to trace environmental pollutants through local and global environment. This is specifically useful as heavy isotopes are often used to synthesize chemicals and then will get incorporated into the natural environment through biodegradation. Thus, tracing position-specific isotopes in the environment can help trace the movement of these pollutants and chemical products.
Case study conclusions
These case studies represent some potential applications for position specific isotope analysis, but certainly not all. The opportunities for samples to measure and processes to characterize are virtually unlimited, and new methodological developments will help make these measurements possible going forward.
References
Analytical chemistry
Isotopes | Position-specific isotope analysis | [
"Physics",
"Chemistry"
] | 4,667 | [
"nan",
"Isotopes",
"Nuclear physics"
] |
53,294,175 | https://en.wikipedia.org/wiki/NGC%203464 | NGC 3464 is a barred spiral galaxy in the constellation of Hydra, discovered 14 January 1886 by Ormond Stone.
Supernovae
Four supernovae have been observed in NGC 3464. SN 2002J (type Ic, mag. 16.8), was detected 21 January 2002. SN 2002hy (type Ib, mag. 16.4) was detected 12 November 2002. SN 2015H (type Ia, mag. 16.9) was discovered 10 February 2015. SN 2019dxd (type II, mag.18.8) was discovered on 24 April 2019.
References
External links
Barred spiral galaxies
Hydra (constellation)
3464
32778
Discoveries by Ormond Stone | NGC 3464 | [
"Astronomy"
] | 144 | [
"Hydra (constellation)",
"Constellations"
] |
53,294,475 | https://en.wikipedia.org/wiki/NGC%20420 | NGC 420 is a lenticular galaxy of type S0 located in the constellation Pisces. It was discovered on September 12, 1784 by William Herschel. It was described by Dreyer as "faint, pretty small, round, brighter middle."
References
External links
0420
17840912
Pisces (constellation)
Lenticular galaxies
004320 | NGC 420 | [
"Astronomy"
] | 74 | [
"Pisces (constellation)",
"Constellations"
] |
53,295,359 | https://en.wikipedia.org/wiki/Invasin | Invasins are a class of bacterial proteins associated with the penetration of pathogens into host cells. Invasins play a role in promoting entry during the initial stage of infection.
In 2007, Als3 was identified as a fungal invasion allowing Candida albicans to infect host cells.
Invasin is a small membrane bound protein that enables the infiltration of cultured mammalian cells by enteric bacteria. The cellular entry of invasin is facilitated through the binding of multiple β1 chain integrins. The interplay between invasin and β1 integrins initiates a reconfiguration of the cytoskeleton in the target cell, culminating in the creation of a groove and the internalization of bacteria through endosomes by the cell. Invasin is expressed inYersinia enterocolitica and Yersinia pseudotuberculosis because of its outermembrane being chromosomally encoded. Invasin demonstrates a significantly enhanced binding affinity to β1 integrins compared to the natural ligands of the receptor. More precisely, it forms a robust attachment to the α5β1 integrin, typically employed by fibronectin, exhibiting roughly 100 times greater strength. This heightened binding capability arises from structural disparities between the two proteins. The extracellular region of invasin adopts a rod-like configuration, with dimensions measuring approximately 180 Å by 30 Å by 30 Å.
Examples
Yersinia pseudotuberculosis
Yersinia pseudotuberculosis, a Gram-negative bacterium and zoonotic pathogen, is accountable for various diseases, spanning mild diarrhea, enterocolitis, lymphatic adenitis, to enduring local inflammation. The invasin D molecule of Y. pseudotuberculosis (InvD) is classified under the invasin (InvA)-type autotransporter proteins, yet its structure and function remain undiscovered. This bacterium induces a food-borne infection marked by a self-limiting mesenteric lymphadenitis that imitates symptoms of appendicitis.
Yersinia enterocolitica
Yersinia enterocolitica is a gram-negative bacillus-shaped bacterium that gives rise to yersiniosis, a zoonotic disease. This infection presents as acute diarrhea, mesenteric adenitis, terminal ileitis, and pseudoappendicitis, occasionally progressing to sepsis. In certain regions, yersinia infections have surpassed shigella and salmonella species as the leading cause of bacterial gastroenteritis. While most cases occur sporadically, notable outbreaks are not uncommon. Humans typically contract yersinia through the consumption of contaminated food or blood transfusions. Y. enterocolitica has been detected in various animals, with pigs serving as the primary reservoir. The pathogen can disseminate within pig herds, contaminating pork products like neck trimmings, tongue, and tonsils, potentially spreading to other meat cuts during the slaughtering process.
Structure
The extracellular region of invasin, composed of the COOH-terminal 497 residues, can be expressed as a soluble protein (Inv497). This protein binds to integrins and facilitates uptake when attached to bacteria or beads. The shortest invasin fragment capable of integrin binding consists of the COOH-terminal 192 amino acids. Notably, this fragment lacks homology with the integrin-binding domains of fibronectin, specifically the fibronectin type III repeats 9 and 10 (Fn-III 9–10). However, invasin and fibronectin share binding sites on α3β1 and α5β1 integrins, with the integrin-binding region of invasin showing no significant sequence identity with the corresponding regions of intimins.
Invasin residues crucial for integrin binding are at positions 903 to 913, constituting helix 1 and the subsequent loop in D5. The disulfide bond between Cys906 and Cys982, a conserved feature in all CTLDs, is essential for integrin binding, likely due to its role in ensuring proper folding. Despite the absence of an Arg-Gly-Asp (RGD) sequence, a critical element in Fn-III 10 for interacting with integrins, invasin relies on Asp911 in Inv497 D5 for integrin binding. Similar to the aspartate in the Fn-III RGD sequence, Asp911 is situated within a loop. Another invasin region, approximately 100 amino acids from Asp911, contains additional residues implicated in integrin binding, including Asp811. This particular invasin segment bears a resemblance to the fibronectin synergy region in Fn-III 9, crucial for optimal α5β1 integrin-dependent cell spreading. Invasin Asp811, positioned in D4 between strands A" and A‴, shares the same surface as Asp911, separated by a distance of 32 Å. The distance between Fn-III 10 Asp1495 in the RGD sequence and Fn-III 9 Asp1373 in the synergy region is also 32 Å, although the side-chain orientation of Asp1373 differs from that of Asp811 in invasin. Within the Fn-III synergy region, the residue for integrin binding is Arg1379. Invasin and host proteins have integrin-binding features that are fairly similar.
The transmembrane segments of outer membrane proteins with known structures exhibit a β-barrel architecture, exemplified by porins. Assuming that the membrane-associated section of invasin also forms a β-barrel, with the cell-binding region extending approximately 180 Å from the bacterial surface, it is positioned to engage host cell integrins. The parallels between invasin and fibronectin indicate the convergent evolution of shared integrin-binding characteristics. Unlike the fibronectin-binding surface, the integrin-binding region of the invasin lacks a cleft; which can result in invasin binding integrins with a larger interface.
Mechanism of action
Entry into M-cells occurs by utilizing a small membrane-bound protein known as invasin. This protein exhibits a strong attraction to the b1 superfamily of integrins present on the outer surface of various mammalian cells. Interestingly, these integrins do not play a role in particle ingestion; instead, they are involved in processes like adhesion to the extracellular matrix, interactions with cell surfaces, migration, and differentiation. The natural partners of these receptors include fibronectin, collagen, vitronectin, and laminin, although invasin forms a stronger bond with them. Notably, invasin selectively binds to specific members within the β1 integrins family. Invasin will bind exclusively to a subset of the b1 subfamily of integrins, specifically α3β1, α4β1, α5β1, α6β1, and αVβ1.
Potential applications
The invasin protein has a particular interest in future use in oral gene discovery. Delivering genes non-virally through oral administration holds great promise for enhancing the efficacy of DNA vaccination and gene therapy applications. Unlike traditional parenteral routes, the oral approach is non-invasive, promoting increased patient compliance and simplified dosing. Furthermore, oral administration enables the production of therapeutic genes locally and systemically. In the case of DNA vaccination, it fosters the development of both mucosal and systemic immunity.
References
External links
Proteins
Virulence factors | Invasin | [
"Chemistry"
] | 1,642 | [
"Biomolecules by chemical classification",
"Proteins",
"Molecular biology"
] |
53,296,282 | https://en.wikipedia.org/wiki/Cloudbleed | Cloudbleed was a Cloudflare buffer overflow disclosed by Project Zero on February 17, 2017. Cloudflare's code disclosed the contents of memory that contained the private information of other customers, such as HTTP cookies, authentication tokens, HTTP POST bodies, and other sensitive data. As a result, data from Cloudflare customers was leaked to all other Cloudflare customers that had access to server memory. This occurred, according to numbers provided by Cloudflare at the time, more than 18,000,000 times before the problem was corrected. Some of the leaked data was cached by search engines.
Discovery
The discovery was reported by Google's Project Zero team. Tavis Ormandy posted the issue on his team's issue tracker and said that he informed Cloudflare of the problem on February 17. In his own proof-of-concept attack he got a Cloudflare server to return "private messages from major dating sites, full messages from a well-known chat service, online password manager data, frames from adult video sites, hotel bookings. We're talking full https requests, client IP addresses, full responses, cookies, passwords, keys, data, everything."
Similarities to Heartbleed
In its effects, Cloudbleed is comparable to the 2014 Heartbleed bug, in that it allowed unauthorized third parties to access data in the memory of programs running on web servers, including data which had been shielded while in transit by TLS. Cloudbleed also likely impacted as many users as Heartbleed since it affected a content delivery network serving nearly two million websites.
Tavis Ormandy, first to discover the vulnerability, immediately drew a comparison to Heartbleed, saying "it took every ounce of strength not to call this issue 'cloudbleed'" in his report.
Reactions
Cloudflare
On Thursday, February 23, 2017, Cloudflare wrote a post noting that:
The bug was serious because the leaked memory could contain private information and because it had been cached by search engines. We have also not discovered any evidence of malicious exploits of the bug or other reports of its existence.
The greatest period of impact was from February 13 and February 18 with around 1 in every 3,300,000 HTTP requests through Cloudflare potentially resulting in memory leakage (that’s about 0.00003% of requests).
Cloudflare acknowledged that the memory could have leaked as early as September 22, 2016. The company also stated that one of its own private keys, used for machine-to-machine encryption, was leaked.
It turned out that the underlying bug that caused the memory leak had been present in our Ragel-based parser for many years but no memory was leaked because of the way the internal NGINX buffers were used. Introducing cf-html subtly changed the buffering which enabled the leakage even though there were no problems in cf-html itself.
John Graham-Cumming, Cloudflare's CTO, noted that Cloudflare clients, such as Uber and OkCupid, weren't directly informed of the leaks due to the security risks involved in the situation. “There was no backdoor communication outside of Cloudflare — only with Google and other search engines,” he said.
Graham-Cumming also said that "Unfortunately, it was the ancient piece of software that contained a latent security problem and that problem only showed up as we were in the process of migrating away from it." He added that his team has already begun testing their software for other possible issues.
Google Project Zero team
Tavis Ormandy initially stated that he was "really impressed with Cloudflare's quick response, and how dedicated they are to cleaning up from this unfortunate issue." However, when Ormandy pressed Cloudflare for additional information, "They gave several excuses that didn't make sense," before sending a draft that "severely downplays the risk to customers."
Uber
Uber stated that the impact on its service was very limited. An Uber spokesperson added "only a handful of session tokens were involved and have since been changed. Passwords were not exposed."
OKCupid
OKCupid CEO Elie Seidman said: "CloudFlare alerted us last night of their bug and we've been looking into its impact on OkCupid members. Our initial investigation has revealed minimal, if any, exposure. If we determine that any of our users has been impacted we will promptly notify them and take action to protect them."
Fitbit
Fitbit stated that they had investigated the incident and only found that a "handful of people were affected". They recommended that concerned customers should change their passwords and clear session tokens by revoking and re-adding the app to their account.
1Password
In a blog post, Jeffery Goldberg stated that no data from 1Password would be at risk due to Cloudbleed, citing the service's use of Secure Remote Password protocol (SRP), in which the client and server prove their identity without sharing any secrets over the network. 1Password data is additionally encrypted using keys derived from the user's master password and a secret account code, which Goldberg claims would protect the credentials even if 1Password's own servers were breached. 1Password did not suggest users change their master password in response to a potential breach involving the bug.
Remediation
Many major news outlets advised users of sites hosted by Cloudflare to change their passwords, as even accounts protected by multi-factor authentication could be at risk. Passwords of mobile apps too could have been impacted. Researchers at Arbor Networks, in an alert, suggested that "For most of us, the only truly safe response to this large-scale information leak is to update our passwords for the Web sites and app-related services we use every day...Pretty much all of them."
Inc. Magazine cybersecurity columnist, Joseph Steinberg, however, advised people not to change their passwords, stating that "the current risk is much smaller than the price to be paid in increased 'cybersecurity fatigue' leading to much bigger problems in the future."
References
External links
List of domains using Cloudflare DNS on GitHub
Simple website that lets you check for affected domains quickly
A Chrome extension that checks bookmarks against potentially affected domains
Cloudbleed explained-How the biggest web cache leak on internet happened
Quantifying the impact of CloudBleed bug
Internet security
Software bugs
2017 in computing
Cloud infrastructure attacks and failures
Cloudflare
Computer security exploits | Cloudbleed | [
"Technology",
"Engineering"
] | 1,354 | [
"Cybersecurity engineering",
"Cloud infrastructure attacks and failures",
"Computer security exploits"
] |
53,299,610 | https://en.wikipedia.org/wiki/Tommy%20Gate | Tommy Gate is an American brand of hydraulic liftgate, or tail lift, manufactured by Woodbine Manufacturing Company. The company was formed in 1965 by Delbert "Bus" Brown and its production facility is located in Woodbine, Iowa.
History
Prior to founding Woodbine Manufacturing Company, Delbert Brown manufactured farming equipment under the name of Brown Manufacturing Company. After inventing what was then one of the first trenching machines, Brown Manufacturing Company was sold to Omaha Steel Works. Three years later, Brown founded Woodbine Manufacturing Company and launched the Tommy Gate brand.
Expansion
The Woodbine manufacturing facility was initially built in 1965 to occupy 70,000 square feet of production space. It expanded in 1980 to 90,000 square feet and once again in 2000 when it grew to 140,000 square feet. The most recent expansion, completed in 2011, grew the plant to an overall 200,000 square feet (including 40,000 square feet of warehouse space).
Products
Tommy Gate manufactures a variety of hydraulic liftgates for trucks and other vehicles. Their main product lines include:
Parallel-arm: Versatile and capable of handling heavy loads.
Rail-gate: Ideal for low-clearance items.
Tuckunder: Compact design for smaller vehicles.
They also offer specialized liftgates like dump-through, level-ride, and side-loader models. Tommy Gate focuses on durability, reliability, and ease of use, with options for customization like remote controls and platform extensions.
References
External links
Companies based in Iowa
Manufacturing companies based in Iowa
Logistics industry in the United States
Mechanical engineering
Hydraulics | Tommy Gate | [
"Physics",
"Chemistry",
"Engineering"
] | 319 | [
"Applied and interdisciplinary physics",
"Physical systems",
"Hydraulics",
"Mechanical engineering",
"Fluid dynamics"
] |
53,299,882 | https://en.wikipedia.org/wiki/Sharp%20pocket%20computer%20character%20sets | The Sharp pocket computer character sets are a number of 8-bit character sets used by various Sharp pocket computers and calculators in the 1980s and mid 1990s.
Character sets
PC-12xx and PC-14xx series
The Sharp PC-14xx series (like the Sharp PC-1403 (1986), PC-1403H or PC-1475) uses an 8-bit extended ASCII character set. With minor exceptions the lower half resembles the 7-bit ASCII character set. The upper half contains a full set of half-width Katakana glyphs as well as a number of graphical and mathematical symbols. The Japanese glyphs are not documented and are available only after enabling an undocumented Japanese mode.
PC-150x series
The Sharp PC-1500 series uses a 7-bit character set derived from ASCII. Differences show the Unicode code point below the glyph.
PC-160x series
The Sharp PC-1600 supports two character sets. In "MODE 0", the character set resembles code page 437, whereas in "MODE 1" certain code points are changed to become compatible with the character set of the predecessor, the PC-1500.
PC-E220 series
The Sharp PC-E220 uses an 8-bit character set where the lower half resembles ASCII and the upper half contains various Greek letters, super- and subscript digits as well as various mathematical symbols.
PC-E500 series
The Sharp PC-E500 (1989) and PC-E500S (1995) use an 8-bit character set almost identical to the IBM PC code page 437. Differences are highlighted.
See also
Calculator character sets
Notes
References
Calculator character sets | Sharp pocket computer character sets | [
"Mathematics"
] | 356 | [
"Calculators",
"Calculator character sets"
] |
53,302,281 | https://en.wikipedia.org/wiki/Optional%20prisoner%27s%20dilemma | The optional prisoner's dilemma (OPD) game models a situation of conflict involving two players in game theory. It can be seen as an extension of the standard prisoner's dilemma game, where players have the option to "reject the deal", that is, to abstain from playing the game. This type of game can be used as a model for a number of real world situations in which agents are afforded the third option of abstaining from a game interaction such as an election.
Payoff matrix
The structure of the optional prisoner's dilemma can be generalized from the standard prisoner's dilemma game setting. In this way, suppose that the two players are represented by the colors, red and blue, and that each player chooses to "Cooperate", "Defect" or "Abstain".
The payoff matrix for the game is shown below:
If both players cooperate, they both receive the reward R for mutual cooperation.
If both players defect, they both receive the punishment payoff P.
If Blue defects while Red cooperates, then Blue receives the temptation payoff T, while Red receives the "sucker's" payoff, S.
Similarly, if Blue cooperates while Red defects, then Blue receives the sucker's payoff S, while Red receives the temptation payoff T.
If one or both players abstain, both receive the loner's payoff L.
The following condition must hold for the payoffs:
T > R > L > P > S
References
Non-cooperative games
Dilemmas | Optional prisoner's dilemma | [
"Mathematics"
] | 311 | [
"Game theory",
"Non-cooperative games"
] |
53,302,354 | https://en.wikipedia.org/wiki/Polymerization-induced%20phase%20separation | Polymerization-induced phase separation (PIPS) is the occurrence of phase separation in a multicomponent mixture induced by the polymerization of one or more components. The increase in molecular weight of the reactive component renders one or more components to be mutually immiscible in one another, resulting in spontaneous phase segregation.
Types
Polymerization-induced phase separation can be initiated either through thermally induced polymerization or photopolymerization. The process general occurs through spinodal decomposition, commonly resulting in the formation of co-continuous phases.
Control over morphology
The morphology of the final phase separated structures are generally random owing to the stochastic nature of the onset and process of phase separation. Several approaches have been investigated to control morphology. Tran-Cong-Miyata and co-workers using periodic irradiation in photoreactive polymer blends to control morphology, specifically width of the resultant spinodal modes in the phase separated morphology. Li and co-workers employed holography, a process of holographic polymerization, in to order to direct the phase separated structure to have the same patterns as the holographic field. Recently, Hosein and co-workers demonstrated that nonlinear optical pattern formations that occur in photopolymer systems may be used to direct the organization of blends to have the same morphology as the light pattern.
Applications
The process is commonly used in control of the morphology of polymer blends, for applications in thermoelectrics, solid-state lighting, polymer electrolytes, composites, membrane formation, and surface pattern formations.
References
__notoc__
Polymer chemistry | Polymerization-induced phase separation | [
"Chemistry",
"Materials_science",
"Engineering"
] | 331 | [
"Materials science",
"Polymer chemistry"
] |
73,190,620 | https://en.wikipedia.org/wiki/Beta%20Cancri%20b | Beta Cancri b is a gas giant exoplanet that orbits the K-type giant Beta Cancri. Its mass is 7.8 Jupiters, it takes 1.7 years to complete one orbit of its star, and is 1.7 AU from its star. Its discovery was announced in 2014.
Discovery
In 2014 evidence was presented of a planet orbiting Beta Cancri. Using radial velocity data from repeated observations of the star, the planet is estimated to have a minimum mass of approximately 7.8 times that of Jupiter, and an orbital period of 605 days.
References
Cancer (constellation)
Exoplanets discovered in 2014
Exoplanets detected by radial velocity | Beta Cancri b | [
"Astronomy"
] | 141 | [
"Cancer (constellation)",
"Constellations"
] |
73,191,707 | https://en.wikipedia.org/wiki/Advanced%20Digital%20Corporation | Advanced Digital Corporation (ADC) was a privately owned American computer company based in California, active from the 1980s to the 1990s. The company was founded by 1980 by a group of engineers, in order to market their single-user and multi-user expansion cards and peripherals for S-100–based computers.
In 1983, ADC introduced a pair of their own S-100 computers, the Super Six and the Super Star. In 1984, they made the pivot to production of expansion cards for the IBM Personal Computer, with one (the PC II, co-produced by Link Technologies of Fremont) allowing the IBM PC to be used as a multi-user platform, with as many as 32 concurrent users. Toward the late 1980s, they introduced their own 386SX-based PC compatible systems under the PowerLite name, to critical acclaim in the tech press. ADC was initially based in Garden Grove, California, employing 35 by mid-1983. In late 1983, they moved to Huntington Beach. By April 1984, their employee headcount reached 75. Its president was Hossein Asadi (born 1961, also known as Hossein Asadibagheri). The company entered bankruptcy in 1990.
Their Huntington Beach headquarters were the subject of an armed robbery in September 1988, with Asadi being bound and gagged while various merchandise was stolen. Asadi sustained no physical injuries.
References
External links
Advanced Digital Corporation history at S100Computers.com
American companies established in 1980
American companies disestablished in 1990
Computer companies established in 1980
Computer companies disestablished in 1990
Defunct companies based in Greater Los Angeles
Defunct computer companies based in California
Defunct computer companies of the United States
Defunct computer hardware companies
Defunct computer systems companies | Advanced Digital Corporation | [
"Technology"
] | 353 | [
"Computing stubs",
"Computer company stubs"
] |
73,192,304 | https://en.wikipedia.org/wiki/HD%20170873 | HD 170873, also known as HR 6954 or rarely 19 G. Telescopii, is a solitary orange-hued star located in the southern constellation Telescopium. It has an apparent magnitude of 6.20, placing it near the limit for naked eye visibility. Gaia DR3 parallax measurements imply a distance of 551 light years and it is currently receding with a heliocentric radial velocity of . At its current distance, HD 170873's brightness is diminished by 0.39 magnitudes due to interstellar dust, and it has an absolute magnitude of −0.31.
HD 170873 is an evolved red giant with a stellar classification of K2 III. It has 3.2 times the mass of the Sun but at the age of 318 million years, it has expanded to 22.6 times the Sun's radius. It radiates 170 times the luminosity of the Sun from its enlarged photosphere at an effective temperature of . It has a near-solar metallicity at [Fe/H] = −0.01 and spins too slowly for its projected rotational velocity to be measured accurately.
References
K-type giants
Telescopium
Telescopii, 19
CD-52 08714
170873
091062
6954 | HD 170873 | [
"Astronomy"
] | 274 | [
"Telescopium",
"Constellations"
] |
73,192,604 | https://en.wikipedia.org/wiki/1945%E2%80%931998 | 1945–1998 is a piece created by Isao Hashimoto showing a time-lapse of every nuclear explosion between 1945 and 1998.
Contents
The piece begins with the two nuclear explosions at Hiroshima and Nagasaki. The United States conducts several nuclear tests after the war. The Soviet Union and United Kingdom then gain nuclear weapons, increasing the number of explosions. The piece continues until it gets to Pakistan's first nuclear test in 1998. The total number of weapons detonated is 2053.
The piece used sound and light to startle the viewer. Months (measured in seconds) are represented by a sound. When a nuclear explosion occurs, a musical sound plays. Different countries have different tones, which sometimes results in a polyphonic composition, overwhelming the viewer.
Reception
The piece is generally well received. The piece is praised for conveying the costs a nuclear war would cause. The piece has been described as "eerie", "scary", and "terrifying".
References
Nuclear weapons
Nuclear warfare | 1945–1998 | [
"Chemistry"
] | 199 | [
"Radioactivity",
"Nuclear warfare"
] |
73,193,257 | https://en.wikipedia.org/wiki/Boletus%20hiratsukae | Boletus hiratsukae is a basidiomycete fungus of the genus Boletus found in Japan. Described by Japanese mycologist Eiji Nagasawa in 1994, it is named after Naohide Hiratsuka. It is characterized by a grey-purple then brown pileipellis and a reticulated stem near the hymenium. It is close to Boletus edulis.
Description
B. hiratsukae is identified by a dark brown to sooty color of both the pileus and stipe, a "dry, pruinose-subvelutinous pileus without any rugosity throughout its development," and a "palisade trichodermium structure of pileipellis" where hyphae often form a bead-like structure with short, inflated terminal and sub-terminal cells.
The pileus is 5 to 13 cm in length and is occasionally depressed when old. The stem is purplish gray but turns distinctly dark gray to brown with age. The flesh is white, also when cut, with no distinct smell. The stipe is dark brown, reticulated with white veins towards the top of the stipe.
Related species
Populations of Boletus variipes found east of the Rocky Mountains are sister species to B. hiratsukae, with B. variipes from Central America and southeastern North America sister to the combined lineage. Within the genus Boletus, B. hiratsukae resembles B. aereus and B. variipes Pk. var. fagicola.
Habitat and distribution
B. hiratsukae is rarely solitary and has been known to reside near conifers.
Ecology
Mycorrhizal associations
B. hiratsukae may form mycorrhizal relationships with members of Pinaceae, particularly P. abies and P. pinus.
Radioactive cesium activity
A study investigating the spatial distribution of radiocaesium in wild mushrooms and soil contaminated by the Fukushima accident concluded that the concentration of radiocaesium in B. hiratsukae did not rely on the distance between the mushrooms.
See also
List of Boletus species
References
hiratsukae
Edible fungi
Fungi of Asia
Fungi described in 1994
Fungus species | Boletus hiratsukae | [
"Biology"
] | 462 | [
"Fungi",
"Fungus species"
] |
73,195,282 | https://en.wikipedia.org/wiki/Elaiophore | An elaiophore (from Gr. elaion -oil and phorein -carry) is a plant organ that secretes oil.
A distinction is made in:
epithelial elaiophors: oil glands
trichome eaiophores: glandular hairs.
The oils consist of fatty acids and/or glycerides, but may also contain other components such as aldehydes, amino acids, carbohydrates, carotenoids, hydrocarbons, ketones, phenolic compounds, saponins and terpenes.
Elaiophores occur in the flowers of some families, such as Malpighiaceae, Scrophulariaceae, Iridaceae, Cucurbitaceae, Primulaceae and Solanaceae. Elaiophores can be present on the axial part of the sepals or corollas, on the surface of the lip, at the base of stamens (as in Lysimachia vulgaris) and also on the callus.
The oils secreted by the elaiophores act as attractants for pollinating insects. Representatives of several bee families collect these oils to add to the food of the larvae or to line the nest, including the families and subfamilies Melittidae, Ctenoplectrini, Apidae and Anthophorini. Bees of the subfamily Ctenoplectrini have specialized oil-collecting structures such as pads or combs on the ventral thorax or on the front and middle legs. Bees visiting flowers with trichome elaiophores generally have pads, and bees visiting flowers with epithelial elaiophores have brush-like combs.
References
Sources
Gerhard Wagenitz: Wörterbuch der Botanik. Morphologie, Anatomie, Taxonomie, Evolution. 2., erweiterte Auflage. Nikol, Hamburg 2008, .
Vogel, S. 1969. Flowers offering fatty oil instead of nectar. XI Proc. Intl. Bot. Congress, Seattle, p. 229. Abstr.
Stephen L. Buchmann. 1987. The Ecology of Oil Flowers and their Bees. Annual Review of Ecology and Systematics, Vol. 18 pp. 343-369
Pacek-Bieniek A., Budowa i aktywność elajoforów w kwiatach wybranych gatunków z rodziny storczykowatych (Orchidaceae), Uniwersytet Przyrodniczy w Lublinie, 2011.
Plant morphology | Elaiophore | [
"Biology"
] | 542 | [
"Plant morphology",
"Plants"
] |
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