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Some research has suggested that a deregulation of cAMP pathways and an aberrant activation of cAMP-controlled genes is linked to the growth of some cancers. | 1 | Applied and Interdisciplinary Chemistry |
CKLF like MARVEL transmembrane domain-containing 7 (i.e. CMTM7), previously termed chemokine-like factor superfamily 7 (i.e. CKLFSF7), is a protein that in humans is encoded by the CMTM7 gene. This gene, which is located in band 22 on the short (i.e. "p") arm of chromosome 3, and the protein that it encodes belong to the CKLF-like MARVEL transmembrane domain-containing family. Through the process of alternative splicing, the CMTM7 gene encodes two isoforms, CMTM7-v1 and CMTM7-v2, with CMTM7-v1 being the main form expressed and studied. CMTM7 proteins are widely expressed in normal human tissues. | 1 | Applied and Interdisciplinary Chemistry |
Octafluoropropane can be produced either by electrochemical fluorination or by the Fowler process using cobalt fluoride. | 1 | Applied and Interdisciplinary Chemistry |
The L-arabinose operon houses genes coding for arabinose-digesting enzymes. These function to break down arabinose as an alternative source for energy when glucose is low or absent. The operon consists of a regulatory repressor gene (araC), three control sites (ara02, ara01, araI1, and araI2), two promoters (Parac/ParaBAD) and three structural genes (araBAD). Once produced, araC acts as repressor by binding to the araI region to form a loop which prevents polymerases from binding to the promotor and transcribing the structural genes into proteins.
In the absence of Arabinose and araC (repressor), loop formation is not initiated and structural gene expression will be lower. In the absence of Arabinose but presence of araC, araC regions form dimers, and bind to bring ara02 and araI1 domains closer by loop formation. In the presence of both Arabinose and araC, araC binds with the arabinose and acts as an activator. This conformational change in the araC no longer can form a loop, and the linear gene segment promotes RNA polymerase recruitment to the structural araBAD region. | 1 | Applied and Interdisciplinary Chemistry |
A large fraction of human tumor mutations are effectively patient-specific. Therefore, neoantigens may also be based on individual tumor genomes. Deep-sequencing technologies can identify mutations within the protein-coding part of the genome (the exome) and predict potential neoantigens. In mice models, for all novel protein sequences, potential MHC-binding peptides were predicted. The resulting set of potential neoantigens was used to assess T cell reactivity. Exome–based analyses were exploited in a clinical setting, to assess reactivity in patients treated by either tumor-infiltrating lymphocyte (TIL) cell therapy or checkpoint blockade. Neoantigen identification was successful for multiple experimental model systems and human malignancies.
The false-negative rate of cancer exome sequencing is low—i.e.: the majority of neoantigens occur within exonic sequence with sufficient coverage. However, the vast majority of mutations within expressed genes do not produce neoantigens that are recognized by autologous T cells.
As of 2015 mass spectrometry resolution is insufficient to exclude many false positives from the pool of peptides that may be presented by MHC molecules. Instead, algorithms are used to identify the most likely candidates. These algorithms consider factors such as the likelihood of proteasomal processing, transport into the endoplasmic reticulum, affinity for the relevant MHC class I alleles and gene expression or protein translation levels.
The majority of human neoantigens identified in unbiased screens display a high predicted MHC binding affinity. Minor histocompatibility antigens, a conceptually similar antigen class are also correctly identified by MHC binding algorithms. Another potential filter examines whether the mutation is expected to improve MHC binding. The nature of the central TCR-exposed residues of MHC-bound peptides is associated with peptide immunogenicity. | 1 | Applied and Interdisciplinary Chemistry |
Moissan published his first scientific paper, about carbon dioxide and oxygen metabolism in plants, with Dehérain in 1874. He left plant physiology and then turned towards inorganic chemistry; subsequently his research on pyrophoric iron was well received by the two most prominent French inorganic chemists of that time, Henri Étienne Sainte-Claire Deville and Jules Henri Debray. After Moissan received his Ph.D. on cyanogen and its reactions to form cyanures in 1880, his friend Landrine offered him a position at an analytic laboratory. | 0 | Theoretical and Fundamental Chemistry |
This element describes the impedance of a finite-length diffusion with transmissive boundary. It is described by the following equation: | 0 | Theoretical and Fundamental Chemistry |
For many decades, arsenic was used medicinally to treat syphilis. It is still used in sheep dips, rat poisons, wood preservatives, weed killers, and other pesticides. Arsenic is poisonous if it enters the human body. | 1 | Applied and Interdisciplinary Chemistry |
Commercial PCB mixtures were marketed under the following names:
Brazil
* Ascarel
Czech Republic and Slovakia
*Delor
France
*Phenoclor
*Pyralène (both used by Prodolec)
Germany
*Clophen (used by Bayer)
Italy
*Apirolio
*Fenclor
Japan
*Kanechlor (used by Kanegafuchi)
*Santotherm (used by Mitsubishi)
*Pyroclor
Former USSR
*Sovol
*Sovtol
United Kingdom
*Aroclor xxxx (used by Monsanto Company)
*Askarel
United States
*Aroclor xxxx (used by Monsanto Company)
*Asbestol
*Askarel
*Bakola131
*Chlorextol – Allis-Chalmers trade name
*Dykanol (Cornell-Dubilier)
*Hydol
*Inerteen (used by Westinghouse)
*Noflamol
*Pyranol/Pyrenol, Clorinol (used in General Electric's oil-filled "clorinol"-branded metal can capacitors. Utilized from the early 1960s to late 1970s in air conditioning units, Seeburg jukeboxes and Zenith televisions)
* Saf-T-Kuhl
*Therminol FR Series (Monsanto ceased production in 1971). | 1 | Applied and Interdisciplinary Chemistry |
Caesium-134 is found in spent nuclear fuel but is not produced by nuclear weapon explosions, as it is only formed by neutron capture on stable Cs-133, which is only produced by beta decay of Xe-133 with a half-life of 3 days. Cs-134 has a half-life of 2 years and may be a major source of gamma radiation in the first 20 years after discharge.
Caesium-135 is a long-lived fission product with much weaker radioactivity. Neutron capture inside the reactor transmutes much of the xenon-135 that would otherwise decay to Cs-135.
Caesium-137, with a half-life of 30 years, is the main medium-lived fission product, along with Sr-90.
Cs-137 is the primary source of penetrating gamma radiation from spent fuel from 10 years to about 300 years after discharge.
It is the most significant radioisotope left in the area around Chernobyl. | 0 | Theoretical and Fundamental Chemistry |
Early studies of the bioluminescence of Aequorea by E. Newton Harvey had noted that the bioluminescence appears as a ring around the bell, and occurs even in the absence of air. This was remarkable because most bioluminescence reactions require oxygen, and led to the idea that the animals somehow store oxygen. It was later discovered that the apoprotein can stably bind coelenterazine-2-hydroperoxide, and oxygen is required for the regeneration to this active form of aequorin. However, in the presence of calcium ions, the protein undergoes a conformational change and converts its prosthetic group, coelenterazine-2-hydroperoxide, into excited coelenteramide and CO. As the excited coelenteramide relaxes to the ground state, blue light (wavelength of 465 nm) is emitted. Before coelenteramide is exchanged out, the entire protein is still fluorescent blue. because of the connection between bioluminescence and fluorescence, this property was ultimately important in the discovery of the luciferin coelenterazine. | 1 | Applied and Interdisciplinary Chemistry |
The Lagrangian motion of a fluid parcel with position vector x = ξ(α, t) in the Eulerian coordinates is given by
where
: ∂ξ/∂t is the partial derivative of ξ(α, t) with respect to t,
: ξ(α, t) is the Lagrangian position vector of a fluid parcel,
: u(x, t) is the Eulerian velocity,
: x is the position vector in the Eulerian coordinate system,
: α is the position vector in the Lagrangian coordinate system,
: t is time.
Often, the Lagrangian coordinates α are chosen to coincide with the Eulerian coordinates x at the initial time t = t:
If the average value of a quantity is denoted by an overbar, then the average Eulerian velocity vector ū and average Lagrangian velocity vector ū are
Different definitions of the average may be used, depending on the subject of study (see ergodic theory):
* time average,
* space average,
* ensemble average,
* phase average.
The Stokes drift velocity ū is defined as the difference between the average Eulerian velocity and the average Lagrangian velocity:
In many situations, the mapping of average quantities from some Eulerian position x to a corresponding Lagrangian position α forms a problem. Since a fluid parcel with label α traverses along a path of many different Eulerian positions x, it is not possible to assign α to a unique x.
A mathematically sound basis for an unambiguous mapping between average Lagrangian and Eulerian quantities is provided by the theory of the generalized Lagrangian mean (GLM) by Andrews and McIntyre (1978). | 1 | Applied and Interdisciplinary Chemistry |
ClSOOH is used to prepare alkyl sulfates, which are useful as detergents and as chemical intermediates:
:ROH + ClSOH → ROSOH + HCl
An early synthesis of saccharin begins with the reaction of toluene with ClSOOH to give the ortho- and para-toluenesulfonyl chloride derivatives:
:CHCH + 2 ClSOOH → CHCHSOCl + HSO + HCl
Oxidation of the ortho isomer gives the benzoic acid derivative that then is cyclized with ammonia and neutralized with base to afford saccharin.
Reaction with hydrogen peroxide is used to produce peroxydisulfuric acid ("persulfuric acid") and peroxydisulfates. These are used as oxidizing agents and for initiating free radical polymerization, for example to produce polytetrafluoroethylene (Teflon).
Chlorosulfonic acid has been used as an anti-contrail agent in Ryan Model 147 reconnaissance drones, and to produce smoke screens. | 0 | Theoretical and Fundamental Chemistry |
With regard to light sensitivity, particularly in red light which is associated with hypocotyl lengthening, all PRR mutants were observed to be hypo-sensitive with PRR9 showing to be less sensitive. All the double mutants were equal in hyposensitivity as the PRR5 or PRR7 mutants; the triple mutant is extremely hypo-sensitive. | 1 | Applied and Interdisciplinary Chemistry |
CNS is a mixture of chloroacetophenone, chloropicrin and chloroform that is used as a chemical warfare agent. CNS has the lachrymatory effects of chloroacetophenone and choking effects of chloropicrin. It has a flypaper-like odor.
CNS was used as a riot control agent, but it's no longer used now. | 1 | Applied and Interdisciplinary Chemistry |
Hess's law states that the change of enthalpy in a chemical reaction is the same regardless of whether the reaction takes place in one step or several steps, provided the initial and final states of the reactants and products are the same. Enthalpy is an extensive property, meaning that its value is proportional to the system size. Because of this, the enthalpy change is proportional to the number of moles participating in a given reaction.
In other words, if a chemical change takes place by several different routes, the overall enthalpy change is the same, regardless of the route by which the chemical change occurs (provided the initial and final condition are the same). If this were not true, then one could violate the first law of thermodynamics.
Hesss law allows the enthalpy change (ΔH') for a reaction to be calculated even when it cannot be measured directly. This is accomplished by performing basic algebraic operations based on the chemical equations of reactions using previously determined values for the enthalpies of formation.
Combination of chemical equations leads to a net or overall equation. If the enthalpy changes are known for all the equations in the sequence, their sum will be the enthalpy change for the net equation. If the net enthalpy change is negative (), the reaction is exothermic and is more likely to be spontaneous; positive ΔH values correspond to endothermic reactions. (Entropy also plays an important role in determining spontaneity, as some reactions with a positive enthalpy change are nevertheless spontaneous due to an entropy increase in the reaction system.) | 0 | Theoretical and Fundamental Chemistry |
In general, three different excitation conditions are distinguished: resonant, quasi-resonant, and non-resonant. For the resonant excitation, the central energy of the laser corresponds to the lowest exciton resonance of the quantum well. No, or only a negligible amount of the excess, energy is injected to the carrier system. For these conditions, coherent processes contribute significantly to the spontaneous emission. The decay of polarization creates excitons directly. The detection of PL is challenging for resonant excitation as it is difficult to discriminate contributions from the excitation, i.e., stray-light and diffuse scattering from surface roughness. Thus, speckle and resonant Rayleigh-scattering are always superimposed to the incoherent emission.
In case of the non-resonant excitation, the structure is excited with some excess energy. This is the typical situation used in most PL experiments as the excitation energy can be discriminated using a spectrometer or an optical filter. One has to distinguish between quasi-resonant excitation and barrier excitation.
For quasi-resonant conditions, the energy of the excitation is tuned above the ground state but still below the barrier absorption edge, for example, into the continuum of the first subband. The polarization decay for these conditions is much faster than for resonant excitation and coherent contributions to the quantum well emission are negligible. The initial temperature of the carrier system is significantly higher than the lattice temperature due to the surplus energy of the injected carriers. Finally, only the electron-hole plasma is initially created. It is then followed by the formation of excitons.
In case of barrier excitation, the initial carrier distribution in the quantum well strongly depends on the carrier scattering between barrier and the well. | 0 | Theoretical and Fundamental Chemistry |
Studies from various international working groups have revealed a significantly increased amount of Tumor M2-PK in EDTA-plasma samples of patients with renal, lung, breast, cervical and gastrointestinal tumors (oesophagus, stomach, pancreas, colon, rectum), as well as melanoma, which correlated with the tumor stage.
The combination of Tumor M2-PK with the appropriate classical tumor marker, such as CEA for bowel cancer, CA 19-9 for pancreatic cancer and CA 72-4 for gastric cancer, significantly increases the sensitivity to detect various cancers.
An important application of the Tumor M2-PK test in EDTA-plasma is for follow-up during tumor therapy, to monitor the success or failure of the chosen treatment, as well as predicting the chances of a “cure” and survival.
If Tumor M2-PK levels decrease during therapy and then remain low after therapy it points towards successful treatment. An increase in the Tumor M2-PK values during or after therapy points towards relapse and/or metastasis.
Increased Tumor M2-PK values can sometimes also occur in severe inflammatory diseases, which must be excluded by differential diagnosis. | 1 | Applied and Interdisciplinary Chemistry |
In geometry, the mirror image of an object or two-dimensional figure is the virtual image formed by reflection in a plane mirror; it is of the same size as the original object, yet different, unless the object or figure has reflection symmetry (also known as a P-symmetry).
Two-dimensional mirror images can be seen in the reflections of mirrors or other reflecting surfaces, or on a printed surface seen inside-out. If we first look at an object that is effectively two-dimensional (such as the writing on a card) and then turn the card to face a mirror, the object turns through an angle of 180° and we see a left-right reversal in the mirror. In this example, it is the change in orientation rather than the mirror itself that causes the observed reversal. Another example is when we stand with our backs to the mirror and face an object that is in front of the mirror. Then we compare the object with its reflection by turning ourselves 180°, towards the mirror. Again we perceive a left-right reversal due to a change in our orientation. So, in these examples the mirror does not actually cause the observed reversals. | 0 | Theoretical and Fundamental Chemistry |
The instantaneous motion of a rigid body may be the combination of rotation about an axis (the screw axis) and a translation along that axis. This screw move is characterized by the velocity vector for the translation and the angular velocity vector in the same or opposite direction. If these two vectors are constant and along one of the principal axes of the body, no external forces are needed for this motion (moving and spinning]]). As an example, if gravity and drag are ignored, this is the motion of a bullet fired from a rifled gun. | 0 | Theoretical and Fundamental Chemistry |
In industrial processes, the reduction of metal oxides is often effected by a carbothermic reaction, using carbon as a reducing agent. Carbon is available cheaply as coal, which can be rendered to coke. When carbon reacts with oxygen it forms the gaseous oxides carbon monoxide and carbon dioxide, so the thermodynamics of its oxidation is different from that for metals: its oxidation has a more negative ΔG with the higher temperatures (above 700 °C). Carbon can thus serve as reducing agent. Using this property, reduction of metals may be performed as a double redox reaction at relatively low temperature. | 1 | Applied and Interdisciplinary Chemistry |
NAPCO began developing composite cow breeds in 1982 when they created the Alexandria composite by breeding Braham Bulls and Shorthorn cow herds. The Alexandria composite is a species of cow that is specific to the NAPCO. The composite was developed at NAPCOs Alexandria station in the Northern Territory. The Alexandria station possess a land mass of 1,641,416 hectares which are home to some 80,000 of the companys cattle. It exhibits features such as a stronger carcass yield, reduced fat cover, improved temperament and environmental adaptation, as well as improved fertility. The Barkalay Tableland in Australias Northern Rangeland industry is home to 3,000 Alexandria composites. In 1995 NAPCO also developed the Kynuna composite which is a product of the remaining Shorthorn Herd that were bread with Braham Bulls to produce the Alexandria composite. The Boomarra station in Queensland is the breeding headquarters for the companys Kynuna composite. It is currently in possession of 10,000 individual cows which NAPCO distributes amongst its other properties. The development of the Kynuna composite also utilised Tuli and Red Angus cows, breeding them with Shorthorn species. The composites are closely monitored according to three particular traits; reproductive rates, pasture and feedlot growth. The company also partakes in a carcass assessment which draws upon data extracted from analysing feedlot trials and the specie's overall climate durability. Female Kynunas are culled if they fall out of sync with regular times for calving, and therefore are without calves for an extended period of time. Bulls are also closely monitored, with particular attention given to testicle size, physical structure, feet composition and growth which is based on a predominantly grass based diet. | 1 | Applied and Interdisciplinary Chemistry |
where
* is the number of constituent quarks, and
* is the number of constituent antiquarks.
Beta decay just changes neutron to proton or, in the case of positive beta decay (electron capture) proton to neutron so the number of individual quarks doesn't change. It is only the baryon flavor that changes, here labelled as the isospin.
Up and down quarks have total isospin and isospin projections
All other quarks have .
In general | 0 | Theoretical and Fundamental Chemistry |
In crystallography and solid state physics, the Laue equations relate incoming waves to outgoing waves in the process of elastic scattering, where the photon energy or light temporal frequency does not change upon scattering by a crystal lattice. They are named after physicist Max von Laue (1879–1960).
The Laue equations can be written as as the condition of elastic wave scattering by a crystal lattice, where is the scattering vector, , are incoming and outgoing wave vectors (to the crystal and from the crystal, by scattering), and is a crystal reciprocal lattice vector. Due to elastic scattering , three vectors. , , and , form a rhombus if the equation is satisfied. If the scattering satisfies this equation, all the crystal lattice points scatter the incoming wave toward the scattering direction (the direction along ). If the equation is not satisfied, then for any scattering direction, only some lattice points scatter the incoming wave. (This physical interpretation of the equation is based on the assumption that scattering at a lattice point is made in a way that the scattering wave and the incoming wave have the same phase at the point.) It also can be seen as the conservation of momentum as since is the wave vector for a plane wave associated with parallel crystal lattice planes. (Wavefronts of the plane wave are coincident with these lattice planes.)
The equations are equivalent to Braggs law; the Laue equations are vector equations while Braggs law is in a form that is easier to solve, but these tell the same content. | 0 | Theoretical and Fundamental Chemistry |
A vacuum ceramic filter is designed to separate liquids from solids for dewatering of ore concentrates purposes. The device consists of a rotator, slurry tank, ceramic filter plate, distributor, discharge scraper, cleaning device, frame, agitating device, pipe system, vacuum system, automatic acid dosing system, automatic lubricating system, valve and discharge chute. The operation and construction principle of vacuum ceramic filter resemble those of a conventional disc filter, but the filter medium is replaced by a finely porous ceramic disc. The disc material is inert, has a long operational life and is resistant to almost all chemicals. Performance can be optimized by taking into account all those factors which affect the overall efficiency of the separation process. Some of the variables affecting the performance of a vacuum ceramic filter include the solid concentration, speed rotation of the disc, slurry level in the feed basin, temperature of the feed slurry, and the pressure during dewatering stages and filter cake formation. | 0 | Theoretical and Fundamental Chemistry |
Parasitoids have successfully been incorporated into biological pest control programs for many years. Plants can influence the effect of parasitoids on herbivores by releasing chemical cues that attract parasitoids and by providing food sources or domatia. Certain parasitoids may be dependent on this plant relationship. Therefore, in agricultural areas where parasitoid presence is desired, ensuring the crops being grown meet all of these requirements is likely to promote higher parasitoid populations and better pest control.
In a sugar beet crop, when only beets were grown, few aphids were parasitized. However, when collard crops were grown next to the sugar beets, parasitism of aphids increased. Collard crops release more VOCs than sugar beets. As a result, the companion collard plants attract more aphid parasitoids, which kill aphids in both the collard and the nearby sugar beets.
In a related study, ethylene and other compounds released by rice plants in response to brown planthopper feeding attracted a facultative parasitoid that parasitizes brown planthopper eggs.
In another study, the presence of plant extrafloral nectaries in cotton crops caused parasitoids to spend more time in the cotton and led to the parasitization of more moth larva than in cotton crops with no nectaries. Since the publication of this study, most farmers have switched to cotton varieties with nectaries. A separate study found that a naturalized cotton variety emitted seven times more VOCs than cultivated cotton varieties when experiencing feeding damage. It is unknown whether this generalizes to other crops; there are cases of other crops that do not show the same trend.
These findings reveal the specific variables a farmer can manipulate to influence parasitoid populations and illustrate the potential impact parasitoid habitat management can have on pest control. In the case of cotton and other similar high-VOC crop scenarios, there is interest in genetically engineering the chemical pathways of cultivated varieties to selectively produce the high VOC's that were observed in the naturalized varieties in order to attract greater natural enemy populations. This presents challenges but could produce promising pest control opportunities. | 1 | Applied and Interdisciplinary Chemistry |
In the United States, the Human Genome Project first took clear form in February of 1988, with the release of the National Research Council (NRC) report Mapping and Sequencing the Human Genome. YACs are significantly less stable than BACs, producing "chimeric effects" : artifacts where the sequence of the cloned DNA actually corresponds not to a single genomic region but to multiple regions. Chimerism may be due to either co-ligation of multiple genomic segments into a single YAC, or recombination of two or more YACs transformed in the same host Yeast cell. The incidence of chimerism may be as high as 50%. Other artifacts are deletion of segments from a cloned region, and rearrangement of genomic segments (such as inversion). In all these cases, the sequence as determined from the YAC clone is different from the original, natural sequence, leading to inconsistent results and errors in interpretation if the clone's information is relied upon. Due to these issues, the Human Genome Project ultimately abandoned the use of YACs and switched to bacterial artificial chromosomes, where the incidence of these artifacts is very low. In addition to stability issues, specifically the relatively frequent occurrence of chimeric events, YACs proved to be inefficient when generating the minimum tiling path covering the entire human genome. Generating the clone libraries is time consuming. Also, due to the nature of the reliance on sequence tagged sites (STS) as a reference point when selecting appropriate clones, there are large gaps that need further generation of libraries to span. It is this additional hindrance that drove the project to utilize BACs instead. This is due to two factors:
# BACs are much quicker to generate, and when generating redundant libraries of clones, this is essential
# BACs allow more dense coverage with STSs, resulting in more complete and efficient minimum tiling paths generated in silico.
However, it is possible to utilize both approaches, as was demonstrated when the genome of the nematode, C. elegans. There majority of the genome was tiled with BACs, and the gaps filled in with YACs. | 1 | Applied and Interdisciplinary Chemistry |
When a transcript attains the threshold length of ten nucleotides, it enters the RNA exit channel. The polymerase breaks its interactions with the promoter elements and any regulatory proteins associated with the initiation complex that it no longer needs. Promoter escape in eukaryotes requires ATP hydrolysis and, in the case of Pol II-phosphorylation of the CTD. Meanwhile, the transcription bubble collapses down to 12-14 nucleotides, providing kinetic energy required for the escape. | 1 | Applied and Interdisciplinary Chemistry |
Palierne equation connects the dynamic modulus of emulsions with the dynamic modulus of the two phases, size of the droplets and the interphase surface tension. The equation can also be used for suspensions of viscoelastic solid particles in viscoelastic fluids. The equation is named after French rheologist Jean-François Palierne, who proposed the equation in 1991.
For the dilute emulsions Palierne equation looks like:
where is the dynamic modulus of the emulsion, is the dynamic modulus of the continuous phase (matrix), is the volume fraction of the disperse phase and the is given as
where is the dynamic modulus of the disperse phase, is the surface tension between the phases and is the radius of the droplets.
For the suspension of solid particles the value of is given as
The Palierne equation is usually extended for the finite volume concentrations of the disperse phase as: | 0 | Theoretical and Fundamental Chemistry |
AS04-adjuvanted HBV vaccines may be relevant for patients that are non-responsive to other HBV vaccines, including those with immunodeficiency. | 1 | Applied and Interdisciplinary Chemistry |
Funded by the European Commission- Horizon 2020 and European Green Deal
Duration: 4 years (October 2021-September 2025)
Objective: The main scope of the project is to support the EU farm to fork sustainable strategy by providing technical, financial, and political tools and solutions to reduce GHG emissions (by 2030) and achieve carbon neutrality (by 2050) in the food industry. | 0 | Theoretical and Fundamental Chemistry |
The CARS process can be physically explained by using either a classical oscillator model or by using a quantum mechanical model that incorporates the energy levels of the molecule. Classically, the Raman active vibrator is modeled as a (damped) harmonic oscillator with a characteristic frequency of ω. In CARS, this oscillator is not driven by a single optical wave, but by the difference frequency (ω-ω) between the pump and the Stokes beams instead. This driving mechanism is similar to hearing the low combination tone when striking two different high tone piano keys: your ear is sensitive to the difference frequency of the high tones. Similarly, the Raman oscillator is susceptible to the difference frequency of two optical waves. When the difference frequency ω-ω approaches ω, the oscillator is driven very efficiently. On a molecular level, this implies that the electron cloud surrounding the chemical bond is vigorously oscillating with the frequency ω-ω. These electron motions alter the optical properties of the sample, i.e. there is a periodic modulation of the refractive index of the material. This periodic modulation can be probed by a third laser beam, the probe beam. When the probe beam is propagating through the periodically altered medium, it acquires the same modulation. Part of the probe, originally at ω will now get modified to ω+ω-ω, which is the observed anti-Stokes emission. Under certain beam geometries, the anti-Stokes emission may diffract away from the probe beam, and can be detected in a separate direction.
While intuitive, this classical picture does not take into account the quantum mechanical energy levels of the molecule. Quantum mechanically, the CARS process can be understood as follows. Our molecule is initially in the ground state, the lowest energy state of the molecule. The pump beam excites the molecule to a virtual state. A virtual state is not an eigenstate of the molecule and it can not be occupied but it does allow for transitions between otherwise unoccupied real states. If a Stokes beam is simultaneously present along with the pump, the virtual state can be used as an instantaneous gateway to address a vibrational eigenstate of the molecule. The joint action of the pump and the Stokes has effectively established a coupling between the ground state and the vibrationally excited state of the molecule. The molecule is now in two states at the same time: it resides in a coherent superposition of states. This coherence between the states can be probed by the probe beam, which promotes the system to a virtual state. Again, the molecule cannot stay in the virtual state and will fall back instantaneously to the ground state under the emission of a photon at the anti-Stokes frequency. The molecule is no longer in a superposition, as it resides again in one state, the ground state. In the quantum mechanical model, no energy is deposited in the molecule during the CARS process. Instead, the molecule acts like a medium for converting the frequencies of the three incoming waves into a CARS signal (a parametric process). There are, however, related coherent Raman processes that occur simultaneously which do deposit energy into the molecule. | 0 | Theoretical and Fundamental Chemistry |
Water waves of different wave lengths travel with different phase speeds, a phenomenon known as frequency dispersion. For the case of infinitesimal wave amplitude, the terminology is linear frequency dispersion. The frequency dispersion characteristics of a Boussinesq-type of equation can be used to determine the range of wave lengths, for which it is a valid approximation.
The linear frequency dispersion characteristics for the above set A of equations are:
with:
* the phase speed,
* the wave number (, with the wave length).
The relative error in the phase speed for set A, as compared with linear theory for water waves, is less than 4% for a relative wave number . So, in engineering applications, set A is valid for wavelengths larger than 4 times the water depth .
The linear frequency dispersion characteristics of equation B are:
The relative error in the phase speed for equation B is less than 4% for , equivalent to wave lengths longer than 7 times the water depth , called fairly long waves.
For short waves with equation B become physically meaningless, because there are no longer real-valued solutions of the phase speed.
The original set of two partial differential equations (Boussinesq, 1872, equation 25, see set A above) does not have this shortcoming.
The shallow water equations have a relative error in the phase speed less than 4% for wave lengths in excess of 13 times the water depth . | 1 | Applied and Interdisciplinary Chemistry |
By the 1930s, several large classes of natural products were known. Important milestones included:
* Terpenes, first systematically studied by Otto Wallach (Nobel Prize 1910) and later by Leopold Ružička (Nobel Prize 1939)
* Dyes based on porphins (including chlorophyll and heme), studied by Richard Willstätter (Nobel Prize 1915) and Hans Fischer (Nobel Prize 1930)
* Steroids, studied by Heinrich Otto Wieland (Nobel Prize 1927) and Adolf Windaus (Nobel Prize 1928)
* Carotenoids, studied by Paul Karrer (Nobel Prize 1937)
* Vitamins, studied among others by Paul Karrer, Adolf Windaus, Robert R. Williams, Norman Haworth (Nobel Prize 1937), Richard Kuhn (Nobel Prize 1938) and Albert Szent-Györgyi
* Hormones studied by Adolf Butenandt (Nobel Prize 1939) and Edward Calvin Kendall (Nobel Prize 1950)
* Alkaloids and anthocyanins, studied by, among others, Robert Robinson (Nobel Prize 1947) | 1 | Applied and Interdisciplinary Chemistry |
In a closed system, there is a difference observed in the anomeric effect for different substituents on a cyclohexane or tetrahydropyran ring (Y=Oxygen). When X=OH, the generic anomeric effect can be seen, as previously explained. When X=CN, the same results are seen, where the equatorial position is preferred on the cyclohexane ring, but the axial position is preferred on the tetrahydropyran ring. This is consistent with the anomeric effect stabilization. When X=F, the anomeric effect is in fact observed for both rings. However, when X=NH, no anomeric effect stabilization is observed and both systems prefer the equatorial position. This is attributed to both sterics and an effect called the reverse anomeric effect (see below). | 0 | Theoretical and Fundamental Chemistry |
The specification above is incomplete, because for any object or system the magnitude of the compressibility depends strongly on whether the process is isentropic or isothermal. Accordingly, isothermal compressibility is defined:
where the subscript indicates that the partial differential is to be taken at constant temperature.
Isentropic compressibility is defined:
where is entropy. For a solid, the distinction between the two is usually negligible.
Since the density of a material is inversely proportional to its volume, it can be shown that in both cases | 1 | Applied and Interdisciplinary Chemistry |
Nitrogen has two stable isotopes, N and N. The ratio between these is measured relative to nitrogen in ambient air. Nitrogen ratios are frequently linked to agricultural activities. Nitrogen isotope data has also been used to measure the amount of exchange of air between the stratosphere and troposphere using data from the greenhouse gas NO. | 0 | Theoretical and Fundamental Chemistry |
Crystal violet can be used as an alternative to Coomassie brilliant blue (CBB) in staining of proteins separated by SDS-PAGE, reportedly showing a 5x improved sensitivity vs CBB. | 0 | Theoretical and Fundamental Chemistry |
Calcium carbide is sometimes used as source of acetylene, which like ethylene gas, is a ripening agent. However, this is illegal in some countries as, in the production of acetylene from calcium carbide, contamination often leads to trace production of phosphine and arsine. These impurities can be removed by passing the acetylene gas through acidified copper sulfate solution, but, in developing countries, this precaution is often neglected.
Calcium carbide is used in toy cannons such as the Big-Bang Cannon, as well as in bamboo cannons. In the Netherlands calcium carbide is used around new-year to shoot with milk churns.
Calcium carbide, together with calcium phosphide, is used in floating, self-igniting naval signal flares, such as those produced by the Holmes' Marine Life Protection Association.
Calcium carbide is used to determine the moisture content of soil. When soil and calcium carbide are mixed in a closed pressure cylinder, the water content in soil reacts with calcium carbide to release acetylene whose pressure can be measured to determine the moisture content.
Calcium carbide is sold commercially as a mole repellent. When it comes into contact with water, the gas produced drives moles away. | 1 | Applied and Interdisciplinary Chemistry |
Mixtures of complex acids can be resolved by thermometric titration with standard NaOH in aqueous solution. In a mixture of nitric, acetic and phosphoric acids used in the fabrication of semi-conductors, three endpoints could be predicted on the basis of the dissociation constants of the acids:
The key to determine the amount of each acid present in the mixture is the ability to obtain an accurate value for the amount of phosphoric acid present, as revealed by titration of the third proton of HPO.
Figure 10 illustrates a titration plot of this mixture, showing 3 sharp endpoints. | 0 | Theoretical and Fundamental Chemistry |
In cities such as Chicago, green infrastructure projects are aimed at enhancing the environment through sustainability and livability, but often they create more social justice concerns like gentrification. This often happens when urban green spaces added in lower income communities attract wealthier residents, which causes the property values to increase and display the current residence of lower income communities. This often happens in communities that experience extreme heat therefore, green and infrastructure is incorporated, although it reshapes the demographic and the economic landscape of the community. The challenges with incorporating more green infrastructure with a beneficial goal for social justice is often due to how the government funds and fulfills projects. Many of the projects are managed by nonprofits so they are not the focus nor are the proper skills necessary acquired which creates a larger social justice issue like the decrease in affordable housing. This causes a focus on environmental and recreational improvements and neglects the socioeconomic dimensions of sustainability. The planning process of infrastructure should consider the environmental outcomes while also integrating social equity considerations.
The success of implementing green infrastructure within communities that have experienced environmental injustice, like excess exposure to pollution or toxic waste, is dependent on the interaction and collaboration of project managers overseeing green infrastructure sites alongside community residents. The most prominent concerns raised by residents in a community in New Jersey cited concerns regarding the maintenance and upkeep of future green stormwater infrastructure (GSI), the necessity for future GSI projects to be multifaceted rather than universal amongst communities, and advocacy for environmental justice to be implemented within project outlines, as "GSI projects, as part of broader community greening initiatives, do not automatically guarantee EJ and health equity, which may be absent in many shrinking cities." It is important to comprehend the environmental and economical capabilities that green infrastructure can provide, but the environmental inequity in respect to being able to access these spaces must be considered in application of green infrastructure within communities. The imperative need to focus on communities with less accessibilty to ecosystem services and green infrastructure is a major part of ensuring all communities and residents feel the benefits and effects of implementation. | 1 | Applied and Interdisciplinary Chemistry |
Fluorine is something of an anomaly in this circumstance. Above, it is described as a weak electron withdrawing group but this is only partly true. It is correct that fluorine has a -I effect, which results in electrons being withdrawn inductively. However, another effect that plays a role is the +M effect which adds electron density back into the benzene ring (thus having the opposite effect of the -I effect but by a different mechanism). This is called the mesomeric effect (hence +M) and the result for fluorine is that the +M effect approximately cancels out the -I effect. The effect of this for fluorobenzene at the para position is reactivity that is comparable to (or even higher than) that of benzene. Because inductive effects depends strongly on proximity, the meta and ortho positions of fluorobenzene are considerably less reactive than benzene. Thus, electrophilic aromatic substitution on fluorobenzene is strongly para selective.
This -I and +M effect is true for all halides - there is some electron withdrawing and donating character of each. To understand why the reactivity changes occur, we need to consider the orbital overlaps occurring in each. The valence orbitals of fluorine are the 2p orbitals which is the same for carbon - hence they will be very close in energy and orbital overlap will be favourable. Chlorine has 3p valence orbitals, hence the orbital energies will be further apart and the geometry less favourable, leading to less donation the stabilize the carbocationic intermediate, hence chlorobenzene is less reactive than fluorobenzene. However, bromobenzene and iodobenzene are about the same or a little more reactive than chlorobenzene, because although the resonance donation is even worse, the inductive effect is also weakened due to their lower electronegativities. Thus the overall order of reactivity is U-shaped, with a minimum at chlorobenzene/bromobenzene (relative nitration rates compared to benzene = 1 in parentheses): PhF (0.18) > PhCl (0.064) ~ PhBr (0.060) < PhI (0.12). But still, all halobenzenes reacts slower than benzene itself.
Notice that iodobenzene is still less reactive than fluorobenzene because polarizability plays a role as well. This can also explain why phosphorus in phosphanes cant donate electron density to carbon through induction (i.e. +I effect) although it is less electronegative than carbon (2.19 vs 2.55, see electronegativity list) and why hydroiodic acid (pKa = -10) being much more acidic than hydrofluoric acid (pKa = 3). (Thats 10 times more acidic than hydrofluoric acid) | 0 | Theoretical and Fundamental Chemistry |
If multiplexed paired-end sequencing is used, then demultiplexing needs to be done to sort reads for different samples to different files. After the demultiplexing, error correction and read pair elimination based on unique identifier and barcode matching of pairs can be done. Developers adapt the demultiplexing and error correction steps from the CAPP-seq demultiplexing pipeline. | 1 | Applied and Interdisciplinary Chemistry |
The measurement of Ki from dynamic PET scans require tracer kinetic modelling to obtain the model parameters describing the biological processes in bone, as described by Hawkins et al. Since this model has two tissue compartments, it is sometimes called a two-tissue compartmental model. Various different versions of this model exist; however, the most fundamental approach is considered here with two tissue compartments and four tracer-exchange parameters. The whole kinetic modelling process using Hawkins model can be summed up in a single image as seen on the right-hand-side. The following differential equations are solved to obtain the rate constants:
The rate constant K (in units: ml/min/ml) describes the unidirectional clearance of fluoride from plasma to the whole of the bone tissue, k (in units: min) describes the reverse transport of fluoride from the ECF compartment to plasma, k and k (in units min) describe the forward and backward transportation of fluoride from the bone mineral compartment.
K represents the net plasma clearance to bone mineral only. K is a function of both K, reflecting bone blood flow, and the fraction of the tracer that undergoes specific binding to the bone mineral k / (k + k). Therefore,
Hawkins et al. found that the inclusion of an additional parameter called fractional blood volume (BV), representing the vascular tissue spaces within the ROI, improved the data fitting problem, although this improvement was not statistically significant. | 1 | Applied and Interdisciplinary Chemistry |
LSD was evidently in limited recreational use in Australia in the early 1960s, but is believed to have been initially restricted to those with connections to the scientific and the medical communities. LSD overdose was suggested as a possible cause of the January 2, 1962 deaths of CSIRO scientists Gilbert Bogle and his lover, Margaret Chandler, but is very unlikely as there are no known cases of a LSD fatal overdose and other more likely causes of death have been suggested. Large quantities of LSD began to appear in Australia around 1968, and soon permeated the music scene and youth culture in general, especially in the capital cities. The major source of supply during this period is believed to have been American servicemen visiting Australia (mainly Sydney) from Vietnam on "rest and recreation" (R&R) leave, although the growing connections between American and Australian organized crime in the late 1960s may also have facilitated its importation. Recreational LSD use among young people was on a par with that in other countries in Australia by the early 1970s and continued until late in the decade. LSD is not believed to have been manufactured locally in a significant quantity (if at all) and most if not all supplies were sourced from overseas. | 1 | Applied and Interdisciplinary Chemistry |
The catalytic cycle begins with coordination of the Cu(I) species to the olefin, followed by oxidative addition at the γ position and an allylic shift to displace the leaving group. This generates a Cu(III) allyl complex intermediate. Finally, reductive elimination yields the final product and regenerates Cu(I). A Cu(III) intermediate has not been confirmed by isolation from allylic substitutions, but Cu(III) intermediates have been isolated before, thus providing credence to the proposed mechanism. If reductive elimination does not occur fast enough, the γ allyl complex can isomerize to the α allyl complex and yield the α substituted isomer as a byproduct. This side pathway can be prevented by using electron withdrawing ligands on copper, typically a cyanide or halide ligand, which promote reductive elimination. | 0 | Theoretical and Fundamental Chemistry |
The endothelial protease vasohibin uses a cysteine as the nucleophile, but a serine to coordinate the histidine base. Despite the serine being a poor acid, it is still effective in orienting the histidine in the catalytic triad. Some homologues alternatively have a threonine instead of serine at the acid location. | 1 | Applied and Interdisciplinary Chemistry |
The moving particle semi-implicit (MPS) method is a computational method for the simulation of incompressible free surface flows. It is a macroscopic, deterministic particle method (Lagrangian mesh-free method) developed by Koshizuka and Oka (1996). | 1 | Applied and Interdisciplinary Chemistry |
Companion planting approaches in use or being trialled include:
* Square foot gardening attempts to protect plants from issues such as weed infestation by packing them as closely together as possible. This is facilitated by using companion plants, which can be closer together than normal.
* Forest gardening, where companion plants are intermingled to simulate an ecosystem, emulates the interaction of plants of up to seven different heights in a woodland. | 1 | Applied and Interdisciplinary Chemistry |
Once the nucleotides are synthesized they can exchange phosphates among one another in order to create mono-, di-, and tri-phosphate molecules. The conversion of a nucleoside-diphosphate (NDP) to a nucleoside-triphosphate (NTP) is catalyzed by nucleoside diphosphate kinase, which uses ATP as the phosphate donor. Similarly, nucleoside-monophosphate kinase carries out the phosphorylation of nucleoside-monophosphates. Adenylate kinase is a specific nucleotide kinase used for regulating cellular energy fluctuations by the interconversion of 2ADP ⇔ ATP + AMP. | 1 | Applied and Interdisciplinary Chemistry |
Phosphorochloridites are produced by partial alcoholysis of phosphorus trichloride, which proceeds stepwise:
:PCl + ROH → HCl + (RO)PCl (phosphochloridite)
:(RO)PCl + ROH → HCl + (RO)PCl (phosphodichloridite)
:(RO)PCl + ROH → HCl + (RO)P (phosphite)
These reactions are readily controlled with aromatic diols, such as binaphthol and 2,2'-biphenol.
Phosphorochloridites are precursors to diphosphite ligands. When combined with rhodium precursors such as Rh(acac)(CO), these diphosphite ligands afford catalysts that are used industrially for the hydroformylation of alkenes. it and related ligands have become popular in hydroformylation catalysis. | 0 | Theoretical and Fundamental Chemistry |
Since 1980 two theories were worked on to explain adsorption and obtain equations that work. These two are referred to as the chi hypothesis, the quantum mechanical derivation, and excess surface work (ESW). Both these theories yield the same equation for flat surfaces:
where U is the unit step function. The definitions of the other symbols is as follows:
where "ads" stands for "adsorbed", "m" stands for "monolayer equivalence" and "vap" is reference to the vapor pressure of the liquid adsorptive at the same temperature as the solid sample. The unit function creates the definition of the molar energy of adsorption for the first adsorbed molecule by:
The plot of adsorbed versus is referred to as the chi plot. For flat surfaces, the slope of the chi plot yields the surface area. Empirically, this plot was noticed as being a very good fit to the isotherm by Michael Polanyi and also by Jan Hendrik de Boer and Cornelis Zwikker but not pursued. This was due to criticism in the former case by Albert Einstein and in the latter case by Brunauer. This flat surface equation may be used as a "standard curve" in the normal tradition of comparison curves, with the exception that the porous sample's early portion of the plot of versus acts as a self-standard. Ultramicroporous, microporous and mesoporous conditions may be analyzed using this technique. Typical standard deviations for full isotherm fits including porous samples are less than 2%.
Notice that in this description of physical adsorption, the entropy of adsorption is consistent with the Dubinin thermodynamic criterion, that is the entropy of adsorption from the liquid state to the adsorbed state is approximately zero. | 0 | Theoretical and Fundamental Chemistry |
MOBs have been incorporated into composites including cellulose. Additionally, MOBs composed of the copper-containing CuHARS have been shown to provide catalytic function to produce nitric oxide (NO).
Nitric Oxide production: This production of NO was shown to impart anti-microbial activity, and the CuHARS in this case were incorporated into a biodegradable, biocompatible, and renewable resource material, namely cellulose. The release of NO catalzyed by copper from CuHARS may have beneficial biomedical applications.
Anti-Cancer Effects: Both copper- and silver-containing MOBs were shown to have anti-cancer effect on cells in vitro. In the case of possible uses for CuHARS, copper may have a potential role in tumor immunity and for antitumor therapy. Since CuHARS are 100% biodegradable under physiological conditions, copper metabolism of CuHARS may have benefits as an approach for treating glioma.
MOBs as Green Materials using Self-Assembly: Green nanomedicine has been suggested as a path to the next generation of materials for diagnosing brain tumors and for therapeutics, including the use of CuHARS. | 0 | Theoretical and Fundamental Chemistry |
A cured-in-place pipe (CIPP) is a trenchless rehabilitation method used to repair existing pipelines. It is a jointless, seamless pipe lining within an existing pipe. As one of the most widely used rehabilitation methods, CIPP has applications in sewer, water, gas, chemical and district heating pipelines ranging in diameter from 0.1 to 2.8 meters (2–110 inches).
The process of CIPP involves inserting and running a felt lining into a preexisting pipe that is the subject of repair. Resin within the liner is then exposed to a curing element to make it attach to the inner walls of the pipe. Once fully cured, the lining now acts as a new pipeline. | 1 | Applied and Interdisciplinary Chemistry |
The identification of MEKK1-MKK1/2-MPK4 in pathogen signaling has been a tremendous finding. Mekk1, mkk1/mkk2 double and mpk4 mutations are dwarfed and acquire too much of reactive oxygen species. The mutations are considered to be from the enhancement of SA levels, which is partially reversed by bacterial SA hydrolase. Mekk1, mkk1/mkk2 double and mpk4 mutations have cell death occur spontaneously, pathogenesis-related genes and increased resistance to pathogens. MEKK1 appears to have deregulation pathways that are unknown and do not involve MKK1/MKK2 nor MPK4. MEKK1 interact with WRKY53, which is responsible for mekk1 genes set, and alter the activity of WRKY53 that is a short portion of MAPK signaling. Substrates of MPK4 are three proteins: WRKY33, WRKY25, and MKS1. Ternary MKS1-MPK4-WRKY33 complexes have been recognized by nuclear extracts. Recruitment of WRKY33 depends on the phosphorylation of MPK4. Once activated, MPK3 phosphorylates MKS1, which releases WRKY33 from the ternary complex. The free WRKY33 is believed to induce transcription on target genes., allowing for a negative regulation by MPK4. Pathogens have developed mechanisms that inactivate PAMP-induced signaling pathways through the MAPK networks. Andrea Pitzschke and her colleges claim “AvrPto and AvrPtoB interact with the FLS2 receptor and its co-receptor BAK1. AvrPtoB catalyzes the polyubiquitination and subsequent proteasome-dependent degradation of FLS2” (Pitzschke 3). AvrPto interacts with BAK1 and interrupts the binding of FLS2. Pseudomonas syringae have HopAI1, which is a phosphothreonin lyase, and dephosphorylates the threonine residue at the upstream MAPKKs. HopAI1 interacts with MPK3 and MPK6 allowing for flg22 activation to occur. In certain soil-borne pathogens that carry flagellin variants cannot be detected by FLS2, but there is still a triggered innate immune response. The immune response has been shown to be from the EF-Tu protein. Flg22, elf18, FLS2 and EFR have receptors that are in the same subfamily of LRR-RLKs, LRRXII. This means that elf18 and flg22 induce extracellular alkalization, rapid activation of MAPKs, and gene responses that are similar to each other. Although there appears to be an important relationship between MAPKs with EF-Tu-triggered defense, the evidence remains to be unclear. The reason for this unclear relationship is because of Agrobacterium tumefaciens, which infects into segments of plant DNA. EFR1 mutants do not recognize EF-Tu, but there is no research on MAPK activities and efr1. Initiation of defense signaling can be a positive effect to the plant pathogens because activating MPK3 in response to flg22 causes phosphorylation and translocation of virE2 interacting protein 1 (VIP1). VIP1 serves as a shuttle for the pathogenic T-DNA, but the induction of defense genes can occur as well. This allows for the spreading and cessation of the pathogen in the plant, but the pathogen can overcome the problem by attacking VIP1 for proteasome degradation by VirF, which is a virulence factor that encodes an F-box protein. | 1 | Applied and Interdisciplinary Chemistry |
The final case described by Asakura and Oosawa describes two large, hard spheres of diameter , in a solution of small, hard spheres of diameter . If the distance between the center of the spheres, , is less than , then the small spheres are excluded from the space between the large spheres. This results in the area between the large spheres having a reduced concentration of small spheres and therefore reduced entropy. This reduced entropy causes a force to act upon the large spheres pushing them together. This effect was convincingly demonstrated in experiments with vibrofluidized granular materials where attraction can be directly visualized. | 0 | Theoretical and Fundamental Chemistry |
Detection limits may vary greatly with the cross section of the core state of interest and the background signal level. In general, photoelectron cross sections increase with atomic number. The background increases with the atomic number of the matrix constituents as well as the binding energy, because of secondary emitted electrons. For example, in the case of gold on silicon where the high cross section Au4f peak is at a higher kinetic energy than the major silicon peaks, it sits on a very low background and detection limits of 1ppm or better may be achieved with reasonable acquisition times. Conversely for silicon on gold, where the modest cross section Si2p line sits on the large background below the Au4f lines, detection limits would be much worse for the same acquisition time. Detection limits are often quoted as 0.1–1.0 % atomic percent (0.1% = 1 part per thousand = 1000 ppm) for practical analyses, but lower limits may be achieved in many circumstances. | 0 | Theoretical and Fundamental Chemistry |
On metal, patina is a coating of various chemical compounds such as oxides, carbonates, sulfides, or sulfates formed on the surface during exposure to atmospheric elements (oxygen, rain, acid rain, carbon dioxide, sulfur-bearing compounds). In common parlance, weathering rust on steel is often mistakenly referred to as patina. Patina also refers to accumulated changes in surface texture and color that result from normal use of an object such as a coin or a piece of furniture over time.
Archaeologists also use the term patina to refer to a corticated layer that develops over time that is due to a range of complex factors on flint tools and ancient stone monuments. This has led stone tool analysts in recent times to generally prefer the term cortification as a better term to describe the process than patination.
In geology and geomorphology, the term patina is used to refer to discolored film or thin outer layer produced either on or within the surface of a rock or other material by either the development of a weathering rind within the surface of a rock, the formation of desert varnish on the surface of a rock, or combination of both. It also refers to development as the result of weathering of a case-hardened layer, called cortex by geologists, within the surface of either a flint or chert nodule. | 1 | Applied and Interdisciplinary Chemistry |
Roderick MacKinnon commissioned Birth of an Idea, a tall sculpture based on the KcsA potassium channel. The artwork contains a wire object representing the channel's interior with a blown glass object representing the main cavity of the channel structure. | 1 | Applied and Interdisciplinary Chemistry |
In vertebrates, calcium ions, like many other ions, are of such vital importance to many physiological processes that its concentration is maintained within specific limits to ensure adequate homeostasis. This is evidenced by human plasma calcium, which is one of the most closely regulated physiological variables in the human body. Normal plasma levels vary between 1 and 2% over any given time. Approximately half of all ionized calcium circulates in its unbound form, with the other half being complexed with plasma proteins such as albumin, as well as anions including bicarbonate, citrate, phosphate, and sulfate.
Different tissues contain calcium in different concentrations. For instance, Ca (mostly calcium phosphate and some calcium sulfate) is the most important (and specific) element of bone and calcified cartilage. In humans, the total body content of calcium is present mostly in the form of bone mineral (roughly 99%). In this state, it is largely unavailable for exchange/bioavailability. The way to overcome this is through the process of bone resorption, in which calcium is liberated into the bloodstream through the action of bone osteoclasts. The remainder of calcium is present within the extracellular and intracellular fluids.
Within a typical cell, the intracellular concentration of ionized calcium is roughly 100 nM, but is subject to increases of 10- to 100-fold during various cellular functions. The intracellular calcium level is kept relatively low with respect to the extracellular fluid, by an approximate magnitude of 12,000-fold. This gradient is maintained through various plasma membrane calcium pumps that utilize ATP for energy, as well as a sizable storage within intracellular compartments. In electrically excitable cells, such as skeletal and cardiac muscles and neurons, membrane depolarization leads to a Ca transient with cytosolic Ca concentration reaching around 1 µM. Mitochondria are capable of sequestering and storing some of that Ca. It has been estimated that mitochondrial matrix free calcium concentration rises to the tens of micromolar levels in situ during neuronal activity. | 1 | Applied and Interdisciplinary Chemistry |
In 1968, Vinograd was elected to the National Academy of Sciences. In 1970 he received the Kendall Award from the American Chemical Society. In 1972, the Helen Hay Whitney Foundation gave him the T. Duckett Jones Award. He was invited to give a number of honorary lectures, including the Burroughs Wellcome Lecture at Harvard in 1970, the Jesse W. Beams Lecture at the University of Virginia in 1972, and the Falk-Plaut Lecture at Columbia University in 1972. | 0 | Theoretical and Fundamental Chemistry |
Contaminants that may be in untreated water include microorganisms such as viruses, protozoa and bacteria; inorganic contaminants such as salts and metals; organic chemical contaminants from industrial processes and petroleum use; pesticides and herbicides; and radioactive contaminants. Water quality depends on the local geology and ecosystem, as well as human uses such as sewage dispersion, industrial pollution, use of water bodies as a heat sink, and overuse (which may lower the level of the water).
The United States Environmental Protection Agency (EPA) limits the amounts of certain contaminants in tap water provided by US public water systems. The Safe Drinking Water Act authorizes EPA to issue two types of standards:
* primary standards regulate substances that potentially affect human health;
* secondary standards prescribe aesthetic qualities, those that affect taste, odor, or appearance.
The U.S. Food and Drug Administration (FDA) regulations establish limits for contaminants in bottled water. Drinking water, including bottled water, may reasonably be expected to contain at least small amounts of some contaminants. The presence of these contaminants does not necessarily indicate that the water poses a health risk.
In urbanized areas around the world, water purification technology is used in municipal water systems to remove contaminants from the source water (surface water or groundwater) before it is distributed to homes, businesses, schools and other recipients. Water drawn directly from a stream, lake, or aquifer and that has no treatment will be of uncertain quality in terms of potability.
The burden of polluted drinking water disproportionally effects under-represented and vulnerable populations. Communities that lack these clean drinking-water services are at risk of contracting water-borne and pollution-related illnesses like Cholera, diarrhea, dysentery, hepatitis A, typhoid, and polio. These communities are often in low-income areas, where human wastewater is discharged into a nearby drainage channel or surface water drain without sufficient treatment, or is used in agricultural irrigation. | 0 | Theoretical and Fundamental Chemistry |
Solvents with a dielectric constant (more accurately, relative static permittivity) greater than 15 (i.e. polar or polarizable) can be further divided into protic and aprotic. Protic solvents, such as water, solvate anions (negatively charged solutes) strongly via hydrogen bonding. Polar aprotic solvents, such as acetone or dichloromethane, tend to have large dipole moments (separation of partial positive and partial negative charges within the same molecule) and solvate positively charged species via their negative dipole. In chemical reactions the use of polar protic solvents favors the S1 reaction mechanism, while polar aprotic solvents favor the S2 reaction mechanism. These polar solvents are capable of forming hydrogen bonds with water to dissolve in water whereas non-polar solvents are not capable of strong hydrogen bonds. | 1 | Applied and Interdisciplinary Chemistry |
The glycerol phosphate shuttle was first characterized as a major route of mitochondrial hydride transport in the flight muscles of blow flies. It was initially believed that the system would be inactive in mammals due to the predominance of lactate dehydrogenase activity over Glycerol-3-phosphate dehydrogenase 1 (GPD1) until high GPD1 and GPD2 activity were demonstrated in mammalian brown adipose tissue and pancreatic ß-islets. | 1 | Applied and Interdisciplinary Chemistry |
* (self-published)
* (self-published)
Editor: Spectroscopic Properties of Inorganic and Organometallic Compounds, Royal Society of Chemistry, Volume 1 (1968) to Volume 9 (1976) | 0 | Theoretical and Fundamental Chemistry |
Some anionic nitrito complexes undergo acid-induced deoxygenation to give the linear nitrosyl complex.
:[LMNO] + H → [LMNO] + OH
The reaction is reversible in some cases. | 0 | Theoretical and Fundamental Chemistry |
The first description of what would come to be called paramutation was given by William Bateson and Caroline Pellew in 1915, when they described "rogue" peas that always passed their "rogue" phenotype onto their progeny. However, the first formal description of paramutation was given by R.A. Brink at the University of Wisconsin–Madison in the 1950s, who did his work in maize (Zea mays). Brink noticed that specific weakly expressed alleles of the red1 (r1) locus in maize, which encodes a transcription factor that confers red pigment to corn kernels, can heritably change specific strongly expressed alleles to a weaker expression state. The weaker expression state adopted by the changed allele is heritable and can, in turn, change the expression state of other active alleles in a process termed secondary paramutation. Brink showed that the influence of the paramutagenic allele could persist for many generations. | 1 | Applied and Interdisciplinary Chemistry |
A vibration spectrum analyzer allows to analyze vibration amplitudes at various component frequencies, In this way, vibration occurring at specific frequencies can be identified and tracked. Since particular machinery problems generate vibration at specific frequencies, machinery faults can be detected or diagnosed. Vibration Spectrum Analyzers use the signal from different types of sensor, such as: accelerometers, velocity transducers and proximity sensors. The uses of a vibration spectrum analyzer in machine condition monitoring allows to detect and identify machine faults such as: rotor imbalance, shaft misalignment, mechanical looseness, bearing defects, among others. Vibration analysis can also be used in structures to identify structural resonances or to perform modal analysis. | 0 | Theoretical and Fundamental Chemistry |
Reduction may typically be carried out in a round-bottom flask equipped with a drying-tube-capped reflux condenser, a mercury-sealed mechanical stirrer, a thermometer, a nitrogen inlet, and an additional funnel with a pressure-equalizing side arm. The most common solvents used are tetrahydrofuran and diethyl ether. Whatever solvent is used should be anhydrous and pure. Alkoxyaluminium hydrides should be kept as dry as possible and represent a significant fire hazard, particularly when an excess of hydride is used (hydrogen evolves during workup). | 0 | Theoretical and Fundamental Chemistry |
In chemical engineering, a Stefan tube is a device that was devised by Josef Stefan in 1874. It is often used for measuring diffusion coefficients. It comprises a vertical tube, over the top of which a gas flows and at the bottom of which is a pool of volatile liquid that is maintained in a constant-temperature bath. The liquid in the pool evaporates, diffuses through the gas above it in the tube, and is carried away by the gas flow over the tube mouth at the top. One then measures the fall in the level of the liquid in the tube.
The tube conventionally has a narrow diameter, in order to suppress convection.
The way that a Stefan tube is modelled, mathematically, is very similar to how one can model the diffusion of perfume fragrance molecules from (say) a drop of perfume on skin or clothes, evaporating up through the air to a person's nose. There are some differences between the models. However, they turn out to have little effect on results at highly dilute vapour concentrations. | 1 | Applied and Interdisciplinary Chemistry |
Microdialysis takes advantage of a semi-permeable membrane, across which small molecules and ions can pass, while proteins and large polymers cannot cross. By establishing a gradient of solute concentration across the membrane and allowing the system to progress toward equilibrium, the system can slowly move toward supersaturation, at which point protein crystals may form.
Microdialysis can produce crystals by salting out, employing high concentrations of salt or other small membrane-permeable compounds that decrease the solubility of the protein. Very occasionally, some proteins can be crystallized by dialysis salting in, by dialyzing against pure water, removing solutes, driving self-association and crystallization. | 0 | Theoretical and Fundamental Chemistry |
In a bacterium without the proper mutation(s) in rpoB rifampicin binds to a site near the fork in the β subunit and prevents the polymerase from transcribing more than two or three base pairs of any RNA sequence and stopping production of proteins within the cell. Bacteria with mutations in the proper loci along the rpoB gene are resistant to this effect.
Initial studies were done by Jin and Gross to generate rpoB mutations in E. coli that conferred resistance to rifampicin. Three clusters of mutations were identified, cluster I at codons 507-533, cluster II at codons 563-572, and cluster III at codon 687. The majority of these mutations are located within an 81 base pair(bp) region in cluster I dubbed the "Rifampicin Resistance Determining Region (RRDR)". This resistance is typically associated with a mutation wherein a base in the DNA is substituted for another one and the new sequence codes for an amino acid with a large side chain that inhibits the rifampicin molecules from binding to the polymerase.
There are additional mutations which can occur in the β subunit of the polymerase which are located away from the rifampicin binding site that can also result in mild resistance. Potentially indicating that the shape of these areas may affect the formation of the rifampicin binding site.
Nucleic acid probes can detect mutations in rpoB that confer rifampicin resistance. For Mycobacterium tuberculosis, the rifamycin-resistant mutations most commonly encountered involve codons 516, 526, and 531 (numbered, by convention, as in Escherichia coli rpoB). These mutations result in high rifampicin resistance with a relatively low loss of fitness. For Staphylococcus aureus, the rifamycin-resistant mutation most commonly encountered involves codon 526.
In addition to imparting resistance to rifampicin, certain rpoB mutations have been identified in 70% of Vancomycin Intermediate S. aureus (VISA) strains. | 1 | Applied and Interdisciplinary Chemistry |
Anions that interact weakly with cations are termed non-coordinating anions, although a more accurate term is weakly coordinating anion. Non-coordinating anions are useful in studying the reactivity of electrophilic cations. They are commonly found as counterions for cationic metal complexes with an unsaturated coordination sphere. These special anions are essential components of homogeneous alkene polymerisation catalysts, where the active catalyst is a coordinatively unsaturated, cationic transition metal complex. For example, they are employed as counterions for the 14 valence electron cations [(CH)ZrR] (R = methyl or a growing polyethylene chain). Complexes derived from non-coordinating anions have been used to catalyze hydrogenation, hydrosilylation, oligomerization, and the living polymerization of alkenes. The popularization of non-coordinating anions has contributed to increased understanding of agostic complexes wherein hydrocarbons and hydrogen serve as ligands. Non-coordinating anions are important components of many superacids, which result from the combination of Brønsted acids and Lewis acids. | 0 | Theoretical and Fundamental Chemistry |
The Kubelka–Munk equation describes the remission from a sample composed of an infinite number of infinitesimal layers, each having as an absorption fraction, and as a remission fraction. | 0 | Theoretical and Fundamental Chemistry |
Symptoms of mold exposure can include:
* Nasal and sinus congestion, runny nose
* Respiratory problems, such as wheezing and difficulty breathing, chest tightness
* Cough
* Throat irritation
* Sneezing / Sneezing fits | 1 | Applied and Interdisciplinary Chemistry |
When one is considering allylic strain, one needs to consider the possible conformers and the possible stereoelectronic demand of the reaction. For example, in the conformation of (Z)-4-methylpent-2-ene, the molecule isn't frozen in the favored conformer but rotates in the dihedral angle around 30° at <1kcal/mol cost. In stereoselective reactions, there are 2 effects of allylic strain on the reaction which is the sterics effect and the electronic effects. The sterics effect is where the largest group prefer to be the farthest from the alkene. The electronic effect is where the orbitals of the substituents prefer to align anti or outside of the orbitals depending on the reaction. | 0 | Theoretical and Fundamental Chemistry |
Some researchers have examined the use of antimatter as an alternative fusion trigger, mainly in the context of antimatter-catalyzed nuclear pulse propulsion but also nuclear weapons. Such a system, in a weapons context, would have many of the desired properties of a pure fusion weapon. The technical barriers to producing and containing the required quantities of antimatter appear formidable, well beyond present capabilities.
Induced gamma emission is another approach that is currently being researched. Very high energy-density chemicals such as ballotechnics and others have also been suggested as a means of triggering a pure fusion weapon.
Nuclear isomers have also been investigated for use in pure fusion weaponry. Hafnium and tantalum isomers can be induced to emit very strong gamma radiation. Gamma emission from these isomers may have enough energy to start a thermonuclear reaction, without requiring any fissile material. | 0 | Theoretical and Fundamental Chemistry |
In the medical field, "lost" tubes are tubes which have to be replaced after single use. This is not genuine tube cleaning in the proper sense and is very often applied in the medical sector, for instance with cannulas of syringes, infusion needles or medical appliances, such as kidney machines at dialysis. The reasons for the single use are primarily the elimination of infection risks but also the fact that cleaning would be very expensive and, particularly with cheap mass products, out of all proportion in terms of cost. Single use is therefore common practice with tubes of up to 20 mm diameter. For the same reasons as in the medical sector, single use may also be applicable in the food and pharmaceutical process technology, however in these sectors the tube diameters may exceed 20 mm.
In other fields (e.g., in heat exchangers), tubing may also sometimes need to be replaced (or removed, plugged, etc.), but this typically occurs only after a prolonged use, when the tube develops serious flaws (e.g., due to corrosion). | 1 | Applied and Interdisciplinary Chemistry |
Like some other ethers, dioxane combines with atmospheric oxygen upon prolonged exposure to air to form potentially explosive peroxides. Distillation of these mixtures is dangerous. Storage over metallic sodium could limit the risk of peroxide accumulation. | 0 | Theoretical and Fundamental Chemistry |
Conventional nitrogen removal from ammonium-rich wastewater is accomplished in two separate steps: nitrification, which is mediated by aerobic ammonia- and nitrite-oxidizing bacteria and denitrification carried out by denitrifiers, which reduce nitrate to with the input of suitable electron donors. Aeration and input of organic substrates (typically methanol) show that these two processes are:
# Highly energy consuming.
# Associated with the production of excess sludge.
# Produce significant amounts of green-house gases such as and and ozone-depleting NO.
Because anammox bacteria convert ammonium and nitrite directly to anaerobically, this process does not require aeration and other electron donors. Nevertheless, oxygen is still required for the production of nitrite by ammonia-oxidizing bacteria. However, in partial nitritation/anammox systems, oxygen demand is greatly reduced because only half of the ammonium needs to be oxidized to nitrite instead of full conversion to nitrate. The autotrophic nature of anammox bacteria and ammonia-oxidizing bacteria guarantee a low yield and thus less sludge production. Additionally, anammox bacteria easily form stable self-aggregated biofilm (granules) allowing reliable operation of compact systems characterized by high biomass concentration and conversion rate up to 5–10 kg N m. Overall, it has been shown that efficient application of the anammox process in wastewater treatment results in a cost reduction of up to 60% as well as lower emissions. | 1 | Applied and Interdisciplinary Chemistry |
The term shock polar is generally used with the graphical representation of the Rankine–Hugoniot equations in either the hodograph plane or the pressure ratio-flow deflection angle plane. The polar itself is the locus of all possible states after an oblique shock. The shock polar was first introduced by Adolf Busemann in 1929. | 1 | Applied and Interdisciplinary Chemistry |
Metals can be heat-treated to alter the properties of strength, ductility, toughness, hardness and resistance to corrosion. Common heat treatment processes include annealing, precipitation strengthening, quenching, and tempering:
* Annealing process softens the metal by heating it and then allowing it to cool very slowly, which gets rid of stresses in the metal and makes the grain structure large and soft-edged so that, when the metal is hit or stressed it dents or perhaps bends, rather than breaking; it is also easier to sand, grind, or cut annealed metal.
* Quenching is the process of cooling metal very quickly after heating, thus "freezing" the metal's molecules in the very hard martensite form, which makes the metal harder.
* Tempering relieves stresses in the metal that were caused by the hardening process; tempering makes the metal less hard while making it better able to sustain impacts without breaking.
Often, mechanical and thermal treatments are combined in what are known as thermo-mechanical treatments for better properties and more efficient processing of materials. These processes are common to high-alloy special steels, superalloys and titanium alloys. | 1 | Applied and Interdisciplinary Chemistry |
Spore-forming bacteria are of particular concern in the context of planetary protection because their tough endospores may withstand certain sterilization procedures as well as the harsh environments of outer space or planetary surfaces. To test their hardiness on a hypothetical mission to Mars, spores of Bacillus subtilis 168 and Bacillus pumilus SAFR-032 were exposed for 1.5 years to selected parameters of space. It was clearly shown that solar extraterrestrial UV radiation (λ ≥110 nm) as well as the Martian UV spectrum (λ ≥200 nm) was the most deleterious factor applied; in some samples only a few survivors were recovered from spores exposed in monolayers. Spores in multilayers survived better by several orders of magnitude. All other environmental parameters encountered did little harm to the spores, which showed about 50% survival or more. The data demonstrate the high chance of survival of spores on a Mars mission, if protected against solar irradiation. These results will have implications for planetary protection considerations.
The mutagenic efficiency of space was also studied in spores of Bacillus subtilis 168. The data show the unique mutagenic power of space and Martian surface conditions as a consequence of DNA injuries induced by solar UV radiation and space vacuum or the low pressure of Mars. Spores exposed to space demonstrated a much broader and more severe stress response than spores exposed to simulated Martian conditions.
A comparative protein analysis (proteomics) of Bacillus pumilus SAFR-032 spores indicated that proteins conferring resistant traits (superoxide dismutase) were present in higher concentration in space-exposed spores when compared to controls. Also, the first-generation cells and spores derived from space-exposed samples exhibited elevated ultraviolet-C resistance when compared with their ground control counterparts. The data generated are important for calculating the probability and mechanisms of microbial survival in space conditions and assessing microbial contaminants as risks for forward contamination and in situ life detection. | 1 | Applied and Interdisciplinary Chemistry |
The pillar was installed as a trophy in building the Quwwat-ul-Islam mosque and the Qutb complex by Sultan Iltutmish in the 13th century. Its original location, whether on the site itself or from elsewhere, is debated.
According to the inscription of king Chandra, the pillar was erected at Vishnupadagiri (Vishnupada). J. F. Fleet (1898) identified this place with Mathura, because of its proximity to Delhi (the find spot of the inscription) and the citys reputation as a Vaishnavite pilgrimage centre. However, archaeological evidence indicates that during the Gupta period, Mathura was a major centre of Buddhism, although Vaishnavism may have existed there. Moreover, Mathura lies in plains, and only contains some small hillocks and mounds: there is no true giri' (hill) in Mathura.
Based on paleographic similarity to the dated inscriptions from Udayagiri, the Gupta-era iconography, analysis of metallurgy and other evidence, Meera Dass and R. Balasubramaniam (2004) theorized that the iron pillar was originally erected at Udayagiri. According to them, the pillar, with a wheel or discus at the top, was originally located at the Udayagiri Caves. This conclusion was partly based on the fact that the inscription mentions Vishnupada-giri (IAST: Viṣṇupadagiri, meaning "hill with footprint of Viṣṇu"). This conclusion was endorsed and elaborated by Michael D. Willis in his The Archaeology of Hindu Ritual, published in 2009.
The key point in favour of placing the iron pillar at Udayagiri is that this site was closely associated with Chandragupta and the worship of Vishnu in the Gupta period. In addition, there are well-established traditions of mining and working iron in central India, documented particularly by the iron pillar at Dhar and local place names like Lohapura and Lohangī Pīr (see Vidisha). The king of Delhi, Iltutmish, is known to have attacked and sacked Vidisha in the thirteenth century and this would have given him an opportunity to remove the pillar as a trophy to Delhi, just as the Tughluq rulers brought Asokan pillars to Delhi in the 1300s. | 1 | Applied and Interdisciplinary Chemistry |
Combustion spraying equipment produces an intense flame, which may have a peak temperature more than 3,100 °C and is very bright. Electric arc spraying produces ultra-violet light which may damage delicate body tissues. Plasma also generates quite a lot of UV radiation, easily burning exposed skin and can also cause "flash burn" to the eyes. Spray booths and enclosures should be fitted with ultra-violet absorbent dark glass. Where this is not possible, operators, and others in the vicinity should wear protective goggles containing BS grade 6 green glass. Opaque screens should be placed around spraying areas. The nozzle of an arc pistol should never be viewed directly unless it is certain that no power is available to the equipment. | 1 | Applied and Interdisciplinary Chemistry |
In B. Neritina, bryostatin biosynthesis is carried out through a type I polyketide synthase cluster, bry. BryR is the secondary metabolism homolog of HMG-CoA synthase, which is the PKS in bacterial primary metabolism. In the bryostatin pathway, the BryR module catalyzes β-Branching between a local acetoacetyl acceptor acyl carrier protein (ACP-a) and an appropriate donor BryU acetyl-ACP (ACP-d).
The first step involves the loading of a malonyl unit onto a discrete BryU ACP-d within an initial BryA module. The extended BryU product in BryA is then loaded onto a cysteine sidechain of BryR for interaction with ACP-a. Upon interaction, BryR then catalyzes β-Branching, facilitating an aldol reaction between the alpha-carbon of the BryU unit and the β-ketone of ACP-a, yielding a product similar to HMGS products in primary metabolism. After β-Branching, subsequent dehydration by a BryT enoyl-CoA hydratase homolog (ECH), as well as BryA O-methylation and BryB double bond isomerization of the generated HMGS product, are carried out in specific domains of the bry cluster. These post-β-Branching steps generate the vinyl methylester moieties which are found in all natural product bryostatins. Finally, BryC and BryD are responsible for further extension, pyran ring closure, and cyclization of the HMGS product to produce the novel bryostatin product.
In the presence of BryR, ACP-d conversion to holo-ACP-d was observed prior to β-Branching. BryR was shown to have high specificity for ACP-d only after this conversion. Specificity for these protein-bound groups is a feature that differentiates the HMGS homologs found in primary metabolism, where HMGS typically acts on substrates linked to Coenzyme A, from those found in non-ribosomal peptide synthase (NRPS) or PKS pathways such as the bryostatin pathway. | 0 | Theoretical and Fundamental Chemistry |
In the United States, modafinil is classified as a schedule IV controlled substance under US federal law. This means that the drug has a low potential for abuse and dependence compared to other controlled substances. However, it still requires a prescription from a licensed healthcare provider to obtain.
It is illegal to import modafinil to the United States without a Drug Enforcement Administration (DEA)-registered importer and a prescription. Individuals may legally bring modafinil into the US from a foreign country for personal use, limited to 50 dosage units, with a prescription and proper declaration at the border. Under the Pure Food and Drug Act, marketing drugs for off-label uses is prohibited. Cephalon, the manufacturer of Provigil, faced legal issues for promoting off-label uses and paid significant fines in 2008. | 0 | Theoretical and Fundamental Chemistry |
TPVs have been proposed for use in recreational vehicles. Their ability to use multiple fuel sources makes them interesting as more sustainable fuels emerge. TPVs silent operation allows them to replace noisy conventional generators (i.e. during "quiet hours" in national park campgrounds). However, the emitter temperatures required for practical efficiencies make TPVs on this scale unlikely. | 0 | Theoretical and Fundamental Chemistry |
* The process is prone to bulking of solids and the treatment system can become overloaded.
* This can cause the dissolved oxygen content to drop; this may reduce the efficiency of nitrification and the settleability of the sludge.
* Excessive aeration will be required which wastes electricity.
it will create thick foam on upper surface layer. | 0 | Theoretical and Fundamental Chemistry |
Recently, a well-studied quorum quenching bacterial strain (KM1S) was isolated and its AHL degradation kinetics were studied using rapid resolution liquid chromatography (RRLC). RRLC efficiently separates components of a mixture to a high degree of sensitivity, based on their affinities for different liquid phases. It was found that the genome of this strain encoded an inactivation enzyme with distinct motifs targeting the degradation of AHLs. | 1 | Applied and Interdisciplinary Chemistry |
Hexamethyltungsten (W(CH)) was the first example of a molecular trigonal prismatic complex. The figure shows the six carbon atoms arranged at the vertices of a triangular prism with the tungsten at the centre. The hydrogen atoms are not shown.
Some other transition metals have trigonal prismatic hexamethyl complexes, including both neutral molecules such as Mo(CH) and Re(CH) and ions such as and .
The complex Mo(S−CH=CH−S) is also trigonal prismatic, with each S−CH=CH−S group acting as a bidentate ligand with two sulfur atoms binding the metal atom. Here the coordination geometry of the six sulfur atoms around the molybdenum is similar to that in the extended structure of molybdenum disulfide (MoS). | 0 | Theoretical and Fundamental Chemistry |
Iodolactonization (or, more generally, halolactonization) is an organic reaction that forms a ring (the lactone) by the addition of an oxygen and iodine across a carbon-carbon double bond. It is an intramolecular variant of the halohydrin synthesis reaction. The reaction was first reported by M. J. Bougalt in 1904 and has since become one of the most effective ways to synthesize lactones. Strengths of the reaction include the mild conditions and incorporation of the versatile iodine atom into the product.
Iodolactonization has been used in the synthesis of many natural products including those with medicinal applications such as vernolepin and vernomenin, two compounds used in tumor growth inhibition, and vibralactone, a pancreatic lipase inhibitor. Iodolactonization has also been used by Elias James Corey to synthesize numerous prostaglandins. | 0 | Theoretical and Fundamental Chemistry |
The 3-Hydroxypropionate bicycle, also known as 3-HP/malyl-CoA cycle, discovered only in 1989, is utilized by green non-sulfur phototrophs of Chloroflexaceae family, including the maximum exponent of this family Chloroflexus auranticus by which this way was discovered and demonstrated. The 3-Hydroxipropionate bicycle is composed of two cycles and the name of this way comes from the 3-Hydroxyporopionate which corresponds to an intermediate characteristic of it.
The first cycle is a way of synthesis of glyoxylate. During this cycle, two equivalents of bicarbonate are fixed by the action of two enzymes: the Acetyl-CoA carboxylase catalyzes the carboxylation of the Acetyl-CoA to Malonyl-CoA and Propionyl-CoA carboxylase catalyses the carboxylation of propionyl-CoA to methylamalonyl-CoA. From this point a series of reactions lead to the formation of glyoxylate which will thus become part of the second cycle.
In the second cycle, glyoxylate is approximately one equivalent of propionyl-CoA forming methylamalonyl-CoA. This, in turn, is then converted through a series of reactions into citramalyl-CoA. The citramalyl-CoA is split into pyruvate and Acetyl-CoA thanks to the enzyme MMC lyase. At this point the pyruvate is released, while the Acetyl-CoA is reused and carboxylated again at Malonyl-CoA thus reconstituting the cycle.
A total of 19 reactions are involved in 3-hydroxypropionate bicycle and 13 multifunctional enzymes are used. The multifunctionality of these enzymes is an important feature of this pathway which thus allows the fixation of three bicarbonate molecules.
It is a very expensive pathway: 7 ATP molecules are used for the synthesis of the new pyruvate and 3 ATP for the phosphate triose.
An important characteristic of this cycle is that it allows the co-assimilation of numerous compounds making it suitable for the mixotrophic organisms. | 0 | Theoretical and Fundamental Chemistry |
In performance evaluations, LeDock demonstrated strong sampling power and outperformed other commercial and academic alternatives, including, notably Autodock Vina. According to a review from 2017, LeDock was noted for its effectiveness in sampling ligand conformational space, identifying near-native binding poses, and having a flexible docking protocol. The Linux version includes tools for high-throughput virtual screening in the cloud. | 1 | Applied and Interdisciplinary Chemistry |
Khalil Ahmad Qureshi (Urdu: خليل احمد قريشى; HI, SI), is a Pakistani physical chemist and the professor of physical chemistry at the Punjab University. He has published notable papers in nuclear physical chemistry in international scientific journals as well contributing in the advancement of the scientific applications of the civilian usage of the fuel cycle. | 0 | Theoretical and Fundamental Chemistry |
A key concept that might be used for applications is the (numerical) derivative of the solid fraction fs with temperature. A numerical example using a copper zinc alloy at composition Zn 30% in weight is proposed as an example here using the opposite sign for using both temperature and its derivative in the same graph.
Kozlov and Schmid-Fetzer have calculated numerically the derivative of the Scheil curve in an open paper https://iopscience.iop.org/article/10.1088/1757-899X/27/1/012001 and applied it to the growth restriction factor Q in Al-Si-Mg-Cu alloys. | 1 | Applied and Interdisciplinary Chemistry |
The third and last stop codon in the standard genetic code was discovered soon after, and corresponds to the nucleotide triplet "UGA".
To continue matching with the theme of colored minerals, the third nonsense codon came to be known as "opal", which is a type of silica showing a variety of colors. Nonsense mutations that created this premature stop codon were later called opal mutations or umber mutations. | 1 | Applied and Interdisciplinary Chemistry |
Optimal eastern meadow vole habitat consists of moist, dense grassland with substantial amounts of plant litter. Habitat selection is largely influenced by relative ground cover of grasses and forbs; soil temperature, moisture, sodium, potassium, and pH levels; humidity; and interspecific competition. Eastern meadow voles are most commonly associated with sites having high soil moisture. They are often restricted to the wetter microsites when they occur in sympatry with prairie voles (Microtus ochrogaster) or montane voles.
In eastern Massachusetts, eastern meadow vole density on a mosaic of grassy fields and mixed woods was positively correlated with decreasing vertical woody stem density and decreasing shrub cover. Density was highest on plots with more forbs and grasses and less with woody cover; eastern meadow voles preferred woody cover over sparse vegetation where grassy cover was not available.
In West Virginia, the only forested habitats in which eastern meadow voles were captured were seedling stands.
In Pennsylvania, three subadult eastern meadow voles were captured at least 1.6 miles (2.6 km) from the nearest appreciable suitable eastern meadow vole habitat, suggesting they are adapted to long-distance dispersal.
In Ohio, the effects of patch shape and proportion of edge were investigated by mowing strips between study plots. The square plots were 132 feet per side (40 m x 40 m), and the rectangular patches were 52.8 feet by 330 feet (16 m x 100 m). Square habitat patches were not significantly different from rectangular patches in eastern meadow vole density. Edge effects in patches of this size were not found, suggesting eastern meadow voles are edge-tolerant. Habitat patch shape did affect dispersal and space use behaviors. In rectangular patches, home ranges were similar in size to those in square patches, but were elongated.
Eastern meadow voles tend to remain in home ranges and defend at least a portion of their home ranges from conspecifics. Home ranges overlap and have irregular shapes. Home range size depends on season, habitat, and population density: ranges are larger in summer than winter, those in marshes are larger than in meadows, and are smaller at higher population densities. Home ranges vary in size from 0.08 to 2.3 hectares (0.32-0.9 ac). Females have smaller home ranges than males, but are more highly territorial than males; often, juveniles from one litter are still present in the adult female's home range when the next litter is born. Female territoriality tends to determine density in suboptimal habitats; the amount of available forage may be the determining factor in female territory size, so determines reproductive success. | 1 | Applied and Interdisciplinary Chemistry |
Crotonyl-coenzyme A is an intermediate in the fermentation of butyric acid, and in the metabolism of lysine and tryptophan. It is important in the metabolism of fatty acids and amino acids. | 1 | Applied and Interdisciplinary Chemistry |
Copper and its alloys are readily joined by mechanical techniques, such as crimping, staking, riveting, and bolting; or by bonding techniques, such as soldering, brazing and welding. Selection of the best joining technique is determined by service requirements, joint configuration, thickness of components, and alloy composition.
Soldering is the preferred joining method where strong, watertight joints are required, such as for internal gutters, roofing, and flashing applications. A soldered seam joins two pieces of copper into a cohesive unit that expands and contracts as one piece. Well-soldered seams are often stronger than the original base material and provide many years of service.
Mechanical fasteners, such as screws, bolts, and rivets, are often used to strengthen the joints and seams. Continuous, long runs of soldered seams can cause stress fractures and should therefore be avoided.
Common 50-50 tin-lead bar solder is often used for uncoated copper; 60-40 tin-lead solder is used for lead-coated copper. Many lead-free solders are also acceptable.
Adhesives can be used in certain applications. Relatively thin sheet alloys can be bonded to plywood or certain types of foam which act as rigid insulation.
Brazing is the preferred method for joining pipe and tube copper alloys. Copper metal sections are joined with a non-ferrous filler material with a melting point above 800 degrees Fahrenheit but below the melting point of the base metals. Blind or concealed joints are recommended since the color match of silver filler material is fair to poor.
Welding is a process where pieces of copper are effectively melted together, either by flame, electricity, or high pressure. With increasing availability of modern TIG welding equipment, welding of even light-gauge copper decorative elements is gaining acceptance.
Instructional videos are available regarding fluxing and soldering techniques; how to make flat seam solder joints, double-lock standing seams, lap seams, soldering vertical sheet copper lap seams, and stitches (including the butterfly stitch); as well as copper tinning, bending, flaring, and brazing. | 1 | Applied and Interdisciplinary Chemistry |
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