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Quartz fiber filter paper has a high resistance to chemicals, does not absorb NO and SO dioxides, is unaffected by humidity and is easily sterilized. Thus, it is mostly used for air pollution analysis. | 0 | Theoretical and Fundamental Chemistry |
Two RNA genomes are packaged into each retrovirus particle, but, after an infection, each virus generates only one provirus. After infection, reverse transcription is accompanied by template switching between the two genome copies (copy choice recombination). There are two models that suggest why RNA transcriptase switches templates. The first, the forced copy-choice model, proposes that reverse transcriptase changes the RNA template when it encounters a nick, implying that recombination is obligatory to maintaining virus genome integrity. The second, the dynamic choice model, suggests that reverse transcriptase changes templates when the RNAse function and the polymerase function are not in sync rate-wise, implying that recombination occurs at random and is not in response to genomic damage. A study by Rawson et al. supported both models of recombination. From 5 to 14 recombination events per genome occur at each replication cycle. Template switching (recombination) appears to be necessary for maintaining genome integrity and as a repair mechanism for salvaging damaged genomes. | 1 | Applied and Interdisciplinary Chemistry |
There are several software packages in different programming languages that allow easy use of Blosum matrices.
Examples are the [https://pypi.org/project/blosum/ blosum] module for Python, or the BioJava library for Java. | 1 | Applied and Interdisciplinary Chemistry |
As the Mach number of the upstream flow becomes increasingly hypersonic, the equations for the pressure, density, and temperature after the oblique shock wave reach a mathematical limit. The pressure and density ratios can then be expressed as:
For a perfect atmospheric gas approximation using γ = 1.4, the hypersonic limit for the density ratio is 6. However, hypersonic post-shock dissociation of O and N into O and N lowers γ, allowing for higher density ratios in nature. The hypersonic temperature ratio is: | 1 | Applied and Interdisciplinary Chemistry |
The Baldwin–Lomax model is a 0-equation turbulence model used in computational fluid dynamics analysis of turbulent boundary layer flows. | 1 | Applied and Interdisciplinary Chemistry |
A photocyte is a cell that specializes in catalyzing enzymes to produce light (bioluminescence). Photocytes typically occur in select layers of epithelial tissue, functioning singly or in a group, or as part of a larger apparatus (a photophore). They contain special structures termed as photocyte granules. These specialized cells are found in a range of multicellular animals including ctenophora, coelenterates (cnidaria), annelids, arthropoda (including insects) and fishes. Although some fungi are bioluminescent, they do not have such specialized cells. | 1 | Applied and Interdisciplinary Chemistry |
Atmospheric hypoxia occurs naturally at high altitudes. Total atmospheric pressure decreases as altitude increases, causing a lower partial pressure of oxygen, which is defined as hypobaric hypoxia. Oxygen remains at 20.9% of the total gas mixture, differing from hypoxic hypoxia, where the percentage of oxygen in the air (or blood) is decreased. This is common in the sealed burrows of some subterranean animals, such as blesmols. Atmospheric hypoxia is also the basis of altitude training, which is a standard part of training for elite athletes. Several companies mimic hypoxia using normobaric artificial atmosphere. | 0 | Theoretical and Fundamental Chemistry |
In 1802, Joseph Louis Gay-Lussac published results of similar, though more extensive experiments. Gay-Lussac credited Charles earlier work by naming the law in his honor. Gay-Lussac himself is credited with the law describing pressure, which he found in 1809. It states that the pressure exerted on a containers sides by an ideal gas is proportional to its temperature. | 0 | Theoretical and Fundamental Chemistry |
In 1985, the Society used the proceeds from the 10th International Mass Spectrometry Conference to establish 7 Beynon PhD Studentships. In 2007, the Society announced they would initiate summer studentship projects and in 2012 they announced BMSS research grants. | 1 | Applied and Interdisciplinary Chemistry |
Semiconductor materials have energy band gaps, and will generate a pair of electron and hole for each absorbed photon if the energy of the photon is higher than the band gap energy of the semiconductor. This property of semiconductor materials has been successfully used to convert solar energy into electrical energy by photovoltaic devices.
In photocatalysis the electron-hole pair is immediately used to drive a redox reaction. However, the electron-hole pairs suffer from fast recombination. In photoelectrocatalysis, a differential potential is applied to diminish the number of recombinations between the electrons and the holes. This allows an increase in the yield of light's conversion into chemical energy. | 0 | Theoretical and Fundamental Chemistry |
Bacteria, fungi, allergens, and particle-bound semi-volatile organic compounds (SVOCs) can all be found in bedding and pillows with possible consequences for human health given the high amount of exposure each day. Over 47 species of fungi have been identified in pillows, although the typical range of species found in a single pillow varied between four and sixteen. Compared to feather pillows, synthetic pillows typically display a slightly greater variety of fungal species and significantly higher levels of β‐(1,3)‐glucan, which can cause inflammatory responses. The authors concluded that these and related results suggest feather bedding might be a more appropriate choice for asthmatics than synthetics. Some newer bedding products incorporate silver nanoparticles due to their antibacterial, antifungal, and antiviral properties; however, the long-term safety of this additional exposure to these nanoparticles is relatively unknown, and a conservative approach to the use of these products is recommended. | 1 | Applied and Interdisciplinary Chemistry |
It is a tabular and numerical alternative to the water surplus diagram in Water Pinch which can be used to identify opportunities for reduction in feedwater usage and the design of water distribution networks. The WCA is done in three steps, a global analysis of water distribution and consumption in the network, establishing baseline minimum water targets and redesign of the water network to achieve these targets. | 1 | Applied and Interdisciplinary Chemistry |
If there are additional factors preventing boundary movement, such as Zener pinning by particles, then the grain size may be restricted to a much lower value than might otherwise be expected. This is an important industrial mechanism in preventing the softening of materials at high temperature. | 1 | Applied and Interdisciplinary Chemistry |
PDE5 degrades cGMP and therefore inhibits erection. As demonstrated in , inhibition of PDE5 reduces degradation of cGMP and leads to penile erection.
Because of this action PDE5 inhibitors have been developed for the treatment of penile erectile dysfunction. | 1 | Applied and Interdisciplinary Chemistry |
In the greenhouse effect, long wave radiation emitted by a planet is absorbed by certain gases in the atmosphere, reducing longwave emissions to space. Planets with substantial greenhouse atmospheres emit more longwave radiation at the surface than what reaches space. Consequently, such planets have surface temperatures higher than their effective radiation emission temperature. For example, Venus has an effective temperature of approximately , but a surface temperature of . Similarly, Earth has an effective temperature of , but a surface temperature of about due to the greenhouse effect in our lower atmosphere. The surface temperatures of such planets are more accurately estimated by modeling thermal radiation transport through the atmosphere. | 0 | Theoretical and Fundamental Chemistry |
Rett syndrome is a neurodevelopmental disorder involving deterioration of learned language and motor skills, autism, and seizures starting in infancy. Many cases of Rett syndrome are associated with mutations in MECP2, a gene encoding a transcriptional repressor. Mutations in this gene decrease the levels of MeCP2 binding to different promoter sequences, resulting in their overall derepression. The increased expression of these MeCP2 regulated genes in neurons contribute to the Rett syndrome phenotype. | 1 | Applied and Interdisciplinary Chemistry |
In 2007 it was reported that a preliminary dating of a Pločnik copper workshop with a furnace and copper tools to 5,500 BCE, if correct, indicated the Copper Age could have started in Europe 500 years or more earlier than previously thought. The sophisticated furnace and smelter featured earthen pipe-like air vents with hundreds of tiny holes in them. Also there was a chimney to ensure that air goes into the furnace to feed the fire, and smoke comes out away from the workers. Copper workshops from later periods thought to indicate the beginning of the Copper Age were less advanced, lacked chimneys and workers blew air on the fire with bellows.
In 2008, a copper axe was found at Pločnik that was dated to 5,500 BC. This pushed back the start of the Copper Age by 500 years.
A study published in December 2013 reported an in situ discovery of a tin bronze foil from Plocnik dated to . This is the oldest tin bronze so far found in the world - a significant technological advance.
This discovery was further supported by a reanalysis of 14 other tin bronze artefacts from neighbouring sites in Bulgaria and Serbia dated to before 4000 BC. This showed that early tin bronze was more common than previously thought, and developed independently in Europe 1,500 years before the first tin bronze alloys in the Near East.
Another artifact similar to the Plocnik foil is a bronze ring from :fr:Gomolava in Serbia. When analyzed, the ring showed that it has above 8% tin content. The Plocnik foil has 11.7% tin. Tin bronzes above 8% tin require the high annealing temperatures in the range of 500–800C, so this was the temperatures already achieved at that time. These are considerably higher that the temperatures needed for the production of copper artifacts.
According to the authors, the next horizon of bronzes in Serbia is dated to the third millennium BC, so this means there was a significant interruption, when this technology appears to have been lost. In Bulgaria, on the other hand, the production of bronze continued in the fourth millennium BC, but only arsenic bronzes were produced; so this was a different technology. In Serbia, likewise, mostly arsenical bronzes were produced in later times. | 1 | Applied and Interdisciplinary Chemistry |
Lu is a member of the American Chemical Society and the Royal Chemical Society, and has served on the editorial advisory board of Chemical Society Reviews since 2016. She also served on the Inorganic Chemistry editorial advisory board from 2016 to 2018. | 0 | Theoretical and Fundamental Chemistry |
Regarding the volume-temperature relationship, Gay-Lussac attributed his findings to Jacques Charles because he used much of Charless unpublished data from 1787 – hence, the law became known as Charless law or the Law of Charles and Gay-Lussac.
Amontonss, Charles, and Boyles law form the combined gas law. These three gas laws in combination with Avogadros law can be generalized by the ideal gas law.
Gay-Lussac used the formula acquired from ΔV/V = αΔT to define the rate of expansion α for gases. For air, he found a relative expansion ΔV/V = 37.50% and obtained a value of α = 37.50%/100 °C = 1/266.66 °C which indicated that the value of absolute zero was approximately 266.66 °C below 0 °C. The value of the rate of expansion α is approximately the same for all gases and this is also sometimes referred to as Gay-Lussacs Law. See the introduction to this article, and Charless Law. | 0 | Theoretical and Fundamental Chemistry |
A medication (also called medicament, medicine, pharmaceutical drug, medicinal drug or simply drug) is a drug used to diagnose, cure, treat, or prevent disease. Drug therapy (pharmacotherapy) is an important part of the medical field and relies on the science of pharmacology for continual advancement and on pharmacy for appropriate management.
Drugs are classified in many ways. One of the key divisions is by level of control, which distinguishes prescription drugs (those that a pharmacist dispenses only on the order of a physician, physician assistant, or qualified nurse) from over-the-counter drugs (those that consumers can order for themselves). Another key distinction is between traditional small molecule drugs, usually derived from chemical synthesis, and biopharmaceuticals, which include recombinant proteins, vaccines, blood products used therapeutically (such as IVIG), gene therapy, monoclonal antibodies and cell therapy (for instance, stem cell therapies). Other ways to classify medicines are by mode of action, route of administration, biological system affected, or therapeutic effects. An elaborate and widely used classification system is the Anatomical Therapeutic Chemical Classification System. The World Health Organization keeps a list of essential medicines.
Drug discovery and drug development are complex and expensive endeavors undertaken by pharmaceutical companies, academic scientists, and governments. As a result of this complex path from discovery to commercialization, partnering has become a standard practice for advancing drug candidates through development pipelines. Governments generally regulate what drugs can be marketed, how drugs are marketed, and in some jurisdictions, drug pricing. Controversies have arisen over drug pricing and disposal of used drugs. | 1 | Applied and Interdisciplinary Chemistry |
Hybridization is the process of establishing a non-covalent, sequence-specific interaction between two or more complementary strands of nucleic acids into a single complex, which in the case of two strands is referred to as a duplex. Oligonucleotides, DNA, or RNA will bind to their complement under normal conditions, so two perfectly complementary strands will bind to each other readily. In order to reduce the diversity and obtain the most energetically preferred complexes, a technique called annealing is used in laboratory practice. However, due to the different molecular geometries of the nucleotides, a single inconsistency between the two strands will make binding between them less energetically favorable. Measuring the effects of base incompatibility by quantifying the temperature at which two strands anneal can provide information as to the similarity in base sequence between the two strands being annealed. The complexes may be dissociated by thermal denaturation, also referred to as melting. In the absence of external negative factors, the processes of hybridization and melting may be repeated in succession indefinitely, which lays the ground for polymerase chain reaction. Most commonly, the pairs of nucleic bases A=T and G≡C are formed, of which the latter is more stable. | 1 | Applied and Interdisciplinary Chemistry |
Imidazoline is a class of heterocycles formally derived from imidazoles by the reduction of one of the two double bonds. Three isomers are known, 2-imidazolines, 3-imidazolines, and 4-imidazolines. The 2- and 3-imidazolines contain an imine center, whereas the 4-imidazolines contain an alkene group. The 2-Imidazoline group occurs in several drugs. | 0 | Theoretical and Fundamental Chemistry |
Thomson scattering is the elastic scattering of electromagnetic radiation by a free charged particle, as described by classical electromagnetism. It is the low-energy limit of Compton scattering: the particle's kinetic energy and photon frequency do not change as a result of the scattering. This limit is valid as long as the photon energy is much smaller than the mass energy of the particle: , or equivalently, if the wavelength of the light is much greater than the Compton wavelength of the particle (e.g., for electrons, longer wavelengths than hard x-rays). | 0 | Theoretical and Fundamental Chemistry |
Neurotransmitter systems are systems of neurons in the brain expressing certain types of neurotransmitters, and thus form distinct systems. Activation of the system causes effects in large volumes of the brain, called volume transmission. Volume transmission is the diffusion of neurotransmitters through the brain extracellular fluid released at points that may be remote from the target cells with the resulting activation of extrasynaptic receptors, and with a longer time course than for transmission at a single synapse. Such prolonged transmitter action is called tonic transmission, in contrast to the phasic transmission that occurs rapidly at single synapses. | 1 | Applied and Interdisciplinary Chemistry |
Adjusting for inflation, it cost $96 per watt for a solar module in the mid-1970s. Process improvements and a very large boost in production have brought that figure down more than 99%, to 30¢ per watt in 2018
and as low as 20¢ per watt in 2020.
Swansons law is an observation similar to Moores Law that states that solar cell prices fall 20% for every doubling of industry capacity. It was featured in an article in the British weekly newspaper The Economist in late 2012. Balance of system costs were then higher than those of the panels. Large commercial arrays could be built, as of 2018, at below $1.00 a watt, fully commissioned.
As the semiconductor industry moved to ever-larger boules, older equipment became inexpensive. Cell sizes grew as equipment became available on the surplus market; ARCO Solar's original panels used cells in diameter. Panels in the 1990s and early 2000s generally used 125 mm wafers; since 2008, almost all new panels use 156 mm cells. The widespread introduction of flat screen televisions in the late 1990s and early 2000s led to the wide availability of large, high-quality glass sheets to cover the panels.
During the 1990s, polysilicon ("poly") cells became increasingly popular. These cells offer less efficiency than their monosilicon ("mono") counterparts, but they are grown in large vats that reduce cost. By the mid-2000s, poly was dominant in the low-cost panel market, but more recently the mono returned to widespread use.
Manufacturers of wafer-based cells responded to high silicon prices in 2004–2008 with rapid reductions in silicon consumption. In 2008, according to Jef Poortmans, director of IMEC's organic and solar department, current cells use of silicon per watt of power generation, with wafer thicknesses in the neighborhood of 200 microns. Crystalline silicon panels dominate worldwide markets and are mostly manufactured in China and Taiwan. By late 2011, a drop in European demand dropped prices for crystalline solar modules to about $1.09 per watt down sharply from 2010. Prices continued to fall in 2012, reaching $0.62/watt by 4Q2012.
Solar PV is growing fastest in Asia, with China and Japan currently accounting for half of worldwide deployment. Global installed PV capacity reached at least 301 gigawatts in 2016, and grew to supply 1.3% of global power by 2016.
It was anticipated that electricity from PV will be competitive with wholesale electricity costs all across Europe and the energy payback time of crystalline silicon modules can be reduced to below 0.5 years by 2020.
Falling costs are considered one of the biggest factors in the rapid growth of renewable energy, with the cost of solar photovoltaic electricity falling by ~85% between 2010 (when solar and wind made up 1.7% of global electricity generation) and 2021 (where they made up 8.7%). In 2019 solar cells accounted for ~3 % of the world's electricity generation. | 0 | Theoretical and Fundamental Chemistry |
In 1945, Folch married Willa Babcock, who was also a scholar in her own right (in the field of Romance languages) and would later become the academic dean of Tufts University. The couple had three children. Folch died in Boston, Massachusetts on October 3, 1979 at 69 years of age. | 1 | Applied and Interdisciplinary Chemistry |
The Award for Encouraging Disadvantaged Students into Careers in the Chemical Sciences is an American Chemical Society (ACS) award sponsored by The Camille and Henry Dreyfus Foundation, it was instituted in 1993 with the intention of recognizing "significant accomplishments by individuals in stimulating students, underrepresented in the profession, to elect careers in the chemical sciences and engineering." It is awarded by the American Chemical Society as part of their national awards program. Recipients receive $5,000, a certificate, up to $1,500 for travel expenses, and a grant of $10,000 to their designee of choice. The first recipient was Henry C. McBay. | 1 | Applied and Interdisciplinary Chemistry |
Rho-related GTPases from plants, otherwise known as ROPs, are involved in cell polarity through the regulation of cytoskeleton components like actin and microtubules. Unlike mammalian cells, plant cells do not contain heterotrimeric G proteins like Cdc42, Rac, and Rho that are known to regulate cellular polarity.
__TOC__ | 1 | Applied and Interdisciplinary Chemistry |
Sulfur-35 is used to label proteins and nucleic acids. Cysteine is an amino acid containing a thiol group which can be labeled by sulfur-35. For nucleotides that do not contain a sulfur group, the oxygen on one of the phosphate groups can be substituted with a sulfur. This thiophosphate acts the same as a normal phosphate group, although there is a slight bias against it by most polymerases. The maximum theoretical specific activity is . | 0 | Theoretical and Fundamental Chemistry |
mTORC1 activation is required for myofibrillar muscle protein synthesis and skeletal muscle hypertrophy in humans in response to both physical exercise and ingestion of certain amino acids or amino acid derivatives. Persistent inactivation of mTORC1 signaling in skeletal muscle facilitates the loss of muscle mass and strength during muscle wasting in old age, cancer cachexia, and muscle atrophy from physical inactivity. mTORC2 activation appears to mediate neurite outgrowth in differentiated mouse neuro2a cells. Intermittent mTOR activation in prefrontal neurons by β-hydroxy β-methylbutyrate inhibits age-related cognitive decline associated with dendritic pruning in animals, which is a phenomenon also observed in humans. | 1 | Applied and Interdisciplinary Chemistry |
2-Methoxy-1,3-butadiene and ethyl-2-butynoate undergo a Diels-Alder reaction to generate a precursor which is hydrolyzed to obtain Hagemanns ester. By varying the substituents on the butynoate starting material, this approach allows for different C2 alkylated Hagemanns ester derivatives to be synthesized. | 0 | Theoretical and Fundamental Chemistry |
Already in 1914, Wilton extended the Stokes expansion for deep-water surface gravity waves to tenth order, although introducing errors at the eight order. A fifth-order theory for finite depth was derived by De in 1955. For engineering use, the fifth-order formulations of Fenton are convenient, applicable to both Stokes first and second definition of phase speed (celerity). The demarcation between when fifth-order Stokes theory is preferable over fifth-order cnoidal wave theory is for Ursell parameters below about 40.
Different choices for the frame of reference and expansion parameters are possible in Stokes-like approaches to the nonlinear wave problem. In 1880, Stokes himself inverted the dependent and independent variables, by taking the velocity potential and stream function as the independent variables, and the coordinates (x,z) as the dependent variables, with x and z being the horizontal and vertical coordinates respectively. This has the advantage that the free surface, in a frame of reference in which the wave is steady (i.e. moving with the phase velocity), corresponds with a line on which the stream function is a constant. Then the free surface location is known beforehand, and not an unknown part of the solution. The disadvantage is that the radius of convergence of the rephrased series expansion reduces.
Another approach is by using the Lagrangian frame of reference, following the fluid parcels. The Lagrangian formulations show enhanced convergence, as compared to the formulations in both the Eulerian frame, and in the frame with the potential and streamfunction as independent variables.
An exact solution for nonlinear pure capillary waves of permanent form, and for infinite fluid depth, was obtained by Crapper in 1957. Note that these capillary waves – being short waves forced by surface tension, if gravity effects are negligible – have sharp troughs and flat crests. This contrasts with nonlinear surface gravity waves, which have sharp crests and flat troughs.
By use of computer models, the Stokes expansion for surface gravity waves has been continued, up to high (117th) order by . Schwartz has found that the amplitude a (or a) of the first-order fundamental reaches a maximum before the maximum wave height H is reached. Consequently, the wave steepness ka in terms of wave amplitude is not a monotone function up to the highest wave, and Schwartz utilizes instead kH as the expansion parameter. To estimate the highest wave in deep water, Schwartz has used Padé approximants and Domb–Sykes plots in order to improve the convergence of the Stokes expansion.
Extended tables of Stokes waves on various depths, computed by a different method (but in accordance with the results by others), are provided in .
Several exact relationships exist between integral properties – such as kinetic and potential energy, horizontal wave momentum and radiation stress – as found by . He shows, for deep-water waves, that many of these integral properties have a maximum before the maximum wave height is reached (in support of Schwartzs findings). , using a method similar to the one of Schwartz, computed and tabulated integral properties for a wide range of finite water depths (all reaching maxima below the highest wave height). Further, these integral properties play an important role in the conservation laws for water waves, through Noethers theorem.
In 2005, Hammack, Henderson and Segur have provided the first experimental evidence for the existence of three-dimensional progressive waves of permanent form in deep water – that is bi-periodic and two-dimensional progressive wave patterns of permanent form. The existence of these three-dimensional steady deep-water waves has been revealed in 2002, from a bifurcation study of two-dimensional Stokes waves by Craig and Nicholls, using numerical methods. | 1 | Applied and Interdisciplinary Chemistry |
Porphyrins are often used to construct structures in supramolecular chemistry. These systems take advantage of the Lewis acidity of the metal, typically zinc. An example of a host–guest complex that was constructed from a macrocycle composed of four porphyrins. A guest-free base porphyrin is bound to the center by coordination with its four-pyridine substituents. | 1 | Applied and Interdisciplinary Chemistry |
Radiosensitivity is the relative susceptibility of cells, tissues, organs or organisms to the harmful effect of ionizing radiation. | 0 | Theoretical and Fundamental Chemistry |
As they are inert, perfluoroalkanes have essentially no chemical uses, but their physical properties have led to their use in many diverse applications. These include:
*Perfluorocarbon tracer
*Liquid dielectric
*Chemical vapor deposition
*Organic Rankine cycle
*Fluorous biphasic catalysis
*Cosmetics
*Ski waxes
As well as several medical uses:
*Contrast-enhanced ultrasound
*Oxygen Therapeutics
*Blood substitute
*Liquid breathing
*Eye surgery
*Tattoo removal | 1 | Applied and Interdisciplinary Chemistry |
UPdAl is a heavy-fermion superconductor with a hexagonal crystal structure and critical temperature T=2.0K that was discovered in 1991. Furthermore, UPdAl orders antiferromagnetically at T=14K, and UPdAl thus features the unusual behavior that this material, at temperatures below 2K, is simultaneously superconducting and magnetically ordered.
Later experiments demonstrated that superconductivity in UPdAl is magnetically mediated, and UPdAl therefore serves as a prime example for non-phonon-mediated superconductors. | 1 | Applied and Interdisciplinary Chemistry |
In 1856, Robert Forester Mushet "used manganese to improve the ability of steel produced by the Bessemer process to withstand rolling and forging at elevated temperatures."
In 1860, Henry Bessemer invented the use of ferromanganese as a method of introducing manganese in controlled proportions during the production of steel. The advantage of combining powdered iron oxide and manganese oxide together is the lower melting point of the combined alloy compared to pure manganese oxide.
In 1872, Lambert von Pantz produced ferromanganese in a blast furnace, with significantly higher manganese content than was previously possible (37% instead of the previous 12%). This won his company international recognition, including a gold medal at the 1873 World Exposition in Vienna and a certificate of award at the 1876 Centennial Exposition in Pennsylvania.
In an 1876 article, MF Gautier explained that the magnetic oxide needs to be slagged off by the addition of manganese (then in the form of spiegel iron) in order to befit it for rolling. | 1 | Applied and Interdisciplinary Chemistry |
Twintrons were discovered by Donald W. Copertino and Richard B. Hallick as a group II intron within another group II intron in Euglena chloroplast genome. They found that splicing of both the internal and external introns occurs via lariat intermediates. Additionally, twintron splicing was found to proceed by a sequential pathway, the internal intron being removed prior to the excision of the external intron.
Since the original discovery, there have been other reports of Group III twintrons and GroupII/III twintrons in the chloroplast of Euglena gracilis. In 1993 a new type of complex twintron composed of four individual group III introns has been characterized. The external intron was interrupted by an internal intron containing two additional introns. In 1995 scientists discovered the first non-Euglena twintron in cryptomonad alga Pyrenomonas salina. In 2004, several twintrons were discovered in Drosophila. | 1 | Applied and Interdisciplinary Chemistry |
The Heck reaction is the palladium-catalyzed coupling of an aryl or alkenyl halide with an alkene to form a substituted alkene. Intramolecular variants of the reaction may be used to generate cyclic products containing endo or exo double bonds. Ring sizes produced by the intramolecular Heck reaction range from four to twenty-seven atoms. Additionally, in the presence of a chiral palladium catalyst, the intramolecular Heck reaction may be used to establish tertiary or quaternary stereocenters with high enantioselectivity. A number of tandem reactions, in which the intermediate alkylpalladium complex is intercepted either intra- or intermolecularly before β-hydride elimination, have also been developed. | 0 | Theoretical and Fundamental Chemistry |
Once a vortex sheet, it will diffuse due to viscous action. Consider a planar unidirectional flow at ,
impling the presence of a vortex sheet at . The velocity discontinuity smooths out according to
where is the kinematic viscosity. The only non-zero vorticity component is in the direction, given by | 1 | Applied and Interdisciplinary Chemistry |
A sulfite ester (also known as an organosulfite) is a functional group with the structure (RO)(R'O)SO. They are in principle the esters of sulfurous acid, however as the acid cannot be produced they are in practice made via other routes.
They adopt a trigonal pyramidal molecular geometry due to the presence of lone pairs on the sulphur atom.
When substituents R and R' differ, the compound is chiral owing to the stereogenic sulphur centre; when the R groups are the same the compound will have idealised C molecular symmetry.
They are commonly prepared by the reaction of thionyl chloride with alcohols. The reaction is typically performed at room temperature to prevent the alcohol being converted into a chloroalkane. Bases such as pyridine can also be used to promote the reaction:
: 2 ROH + SOCl → (RO)SO + 2 HCl
The pesticides endosulfan and propargite are sulfite esters. Other simple members include ethylene sulfite, dimethyl sulfite, and diphenylsulfite. Many examples have been prepared from diols, such as sugars. Sulfite esters can be powerful alkylation and hydroxyalkylation reagents. | 0 | Theoretical and Fundamental Chemistry |
In the long term, sustainable use of the soil must be guaranteed in order to meet the needs of the world's population. The project brings together numerous universities, research institutions, companies and stakeholders with the aim of creating a web-based, free system to support practical agriculture and land users in making decisions about sustainable land use, environmental protection and agricultural use.
With the active participation of various and numerous stakeholders in and outside Europe, the consortium also aims at legislation at European level, based on scientific data that is processed and modeled in the system.
In the research framework program Horizon 2020, the project is organized under the direction of Fabio Terribile at the University of Naples Federico II. | 1 | Applied and Interdisciplinary Chemistry |
There are various mechanisms for glycosylation, although most share several common features:
*Glycosylation, unlike glycation, is an enzymatic process. Indeed, glycosylation is thought to be the most complex post-translational modification, because of the large number of enzymatic steps involved.
*The donor molecule is often an activated nucleotide sugar.
*The process is non-templated (unlike DNA transcription or protein translation); instead, the cell relies on segregating enzymes into different cellular compartments (e.g., endoplasmic reticulum, cisternae in Golgi apparatus). Therefore, glycosylation is a site-specific modification. | 0 | Theoretical and Fundamental Chemistry |
In 1941, Tisza immigrated to the United States and joined the faculty at the Massachusetts Institute of Technology. His research areas included theoretical physics and the history and philosophy of science, specifically on the foundation of thermodynamics and quantum mechanics. He taught at MIT until 1973. | 0 | Theoretical and Fundamental Chemistry |
Typical domestic exposures are of around 100Bq/m indoors, but specifics of construction and ventilation strongly affect levels of accumulation; a further complication for risk assessment is that concentrations in a single location may differ by a factor of two over an hour, and concentrations can vary greatly even between two adjoining rooms in the same structure.
The distribution of radon concentrations is highly skewed: the larger concentrations have a disproportionately greater weight. Indoor radon concentration is usually assumed to follow a lognormal distribution on a given territory. Thus, the geometric mean is generally used to estimate the "average" radon concentration in an area.
The mean concentration ranges from less than 10 Bq/m to over 100 Bq/m in some European countries. Typical geometric standard deviations found in studies range between 2 and 3, meaning (given the 68–95–99.7 rule) that the radon concentration is expected to be more than a hundred times the mean concentration for 2 to 3% of the cases.
The so-called "Watras incident" in 1984 is named for American construction engineer Stanley Watras, an employee at the Limerick nuclear power plant in the United States, who triggered radiation monitors while leaving work over several days—even though the plant had not yet been fueled, and despite Watras being decontaminated and sent home "clean" each evening. This pointed to a source of contamination outside the power plant, which turned out to be radon levels of 100,000 Bq/m (2.7 nCi/L) in the basement of his home. He was told that living in the home was the equivalent of smoking 135 packs of cigarettes a day, and he and his family had increased their risk of developing lung cancer by 13 or 14 percent. The incident dramatized the fact that radon levels in particular dwellings can occasionally be orders of magnitude higher than typical. Radon soon became a standard homeowner concern, though typical domestic exposures are two to three orders of magnitude lower (100 Bq/m, or 2.5 pCi/L), making individual testing essential to assessment of radon risk in any particular dwelling.
Radon exists in every U.S. state, and about 6% of American houses have elevated levels. The highest average radon concentrations in the United States are found in Iowa and in the Appalachian Mountain areas in southeastern Pennsylvania. Some of the highest readings have been recorded in Mallow, County Cork, Ireland. Iowa has the highest average radon concentrations in the United States due to significant glaciation that ground the granitic rocks from the Canadian Shield and deposited it as soils making up the rich Iowa farmland. Many cities within the state, such as Iowa City, have passed requirements for radon-resistant construction in new homes. In a few locations, uranium tailings have been used for landfills and were subsequently built on, resulting in possible increased exposure to radon. | 1 | Applied and Interdisciplinary Chemistry |
* Casting – molten metal is poured into a shaped mold. Variants of casting include sand casting, investment casting, also called the lost wax process, die casting, and continuous castings. Each of these forms has advantages for certain metals and applications considering factors like magnetism and corrosion.
* Forging – a red-hot billet is hammered into shape.
* Rolling – a billet is passed through successively narrower rollers to create a sheet.
* Extrusion – a hot and malleable metal is forced under pressure through a die, which shapes it before it cools.
* Machining – lathes, milling machines and drills cut the cold metal to shape.
* Sintering – a powdered metal is heated in a non-oxidizing environment after being compressed into a die.
* Fabrication – sheets of metal are cut with guillotines or gas cutters and bent and welded into structural shape.
* Laser cladding – metallic powder is blown through a movable laser beam (e.g. mounted on a NC 5-axis machine). The resulting melted metal reaches a substrate to form a melt pool. By moving the laser head, it is possible to stack the tracks and build up a three-dimensional piece.
* 3D printing – Sintering or melting amorphous powder metal in a 3D space to make any object to shape.
Cold-working processes, in which the product's shape is altered by rolling, fabrication or other processes, while the product is cold, can increase the strength of the product by a process called work hardening. Work hardening creates microscopic defects in the metal, which resist further changes of shape. | 1 | Applied and Interdisciplinary Chemistry |
Strong hydrogen bonds are revealed by downfield shifts in the H NMR spectrum. For example, the acidic proton in the enol tautomer of acetylacetone appears at 15.5, which is about 10 ppm downfield of a conventional alcohol.
In the IR spectrum, hydrogen bonding shifts the stretching frequency to lower energy (i.e. the vibration frequency decreases). This shift reflects a weakening of the bond. Certain hydrogen bonds - improper hydrogen bonds - show a blue shift of the stretching frequency and a decrease in the bond length. H-bonds can also be measured by IR vibrational mode shifts of the acceptor. The amide I mode of backbone carbonyls in α-helices shifts to lower frequencies when they form H-bonds with side-chain hydroxyl groups. The dynamics of hydrogen bond structures in water can be probed by this OH stretching vibration. In the hydrogen bonding network in protic organic ionic plastic crystals (POIPCs), which are a type of phase change material exhibiting solid-solid phase transitions prior to melting, variable-temperature infrared spectroscopy can reveal the temperature dependence of hydrogen bonds and the dynamics of both the anions and the cations. The sudden weakening of hydrogen bonds during the solid-solid phase transition seems to be coupled with the onset of orientational or rotational disorder of the ions. | 0 | Theoretical and Fundamental Chemistry |
The Gross–Pitaevskii model of BEC is a physical approximation valid for certain classes of BECs. By construction, the GPE uses the following simplifications: it assumes that interactions between condensate particles are of the contact two-body type and also neglects anomalous contributions to self-energy. These assumptions are suitable mostly for the dilute three-dimensional condensates. If one relaxes any of these assumptions, the equation for the condensate wavefunction acquires the terms containing higher-order powers of the wavefunction. Moreover, for some physical systems the amount of such terms turns out to be infinite, therefore, the equation becomes essentially non-polynomial. The examples where this could happen are the Bose–Fermi composite condensates, effectively lower-dimensional condensates, and dense condensates and superfluid clusters and droplets. It is found that one has to go beyond the Gross-Pitaevskii equation. For example, the logarithmic term found in the Logarithmic Schrödinger equation must be added to the Gross-Pitaevskii equation along with a Ginzburg-Sobyanin contribution to correctly determine that the speed of sound scales as the cubic root of pressure for Helium-4 at very low temperatures in close agreement with experiment. | 0 | Theoretical and Fundamental Chemistry |
The Swedish assay office, the SP Technical Research Institute of Sweden, is in Borås. The assay office is privatized and the concession, given to the Inspecta Corporation, is an independent, international qualification requirements fulfilling inspection, testing, measurement and certification services provider. Inspecta is accredited by SWEDAC. | 0 | Theoretical and Fundamental Chemistry |
Fast parallel proteolysis (FASTpp) is a method to determine the thermostability of proteins by measuring which fraction of protein resists rapid proteolytic digestion. | 1 | Applied and Interdisciplinary Chemistry |
The Gibbs free energy is so combining the previous results gives
This is the Gibbs free energy for a perfect vdW fluid, or in reduced form | 0 | Theoretical and Fundamental Chemistry |
In a recent publication, REMS technology has received the attention of the European Society for Clinical and Economic Aspects of Osteoporosis, Osteoarthritis and Musculoskeletal Diseases ([http://www.esceo.org/ ESCEO]). In this work, all the available technologies for bone strength assessment and fracture risk estimation have been reviewed and discussed in relation to the clinical needs currently unmet. In this context, REMS has been considered a valuable approach for osteoporosis diagnosis and for fracture risk assessment, at the same time overcoming several of the current limitations acknowledged for the currently available bone health assessment technologies. One example is the work of Degennaro et al. in which a significant BMD reduction has been detected in pregnant women compared to non-pregnant women for the very first time. Several international working groups has used REMS technology for research purposes: Bojincă et al. has proven the effectiveness of REMS BMD estimates in patients affected by rheumatoid arthritis. Kirilova et al. assessed the values of lumbar spine and hip REMS-based BMD in premenopausal and postmenopausal women. In Khu et al. REMS has been used for characterizing the relationship between body mass index and bone health. The growing interest towards REMS is also demonstrated by the publication of scientific review papers focused on this technology. | 0 | Theoretical and Fundamental Chemistry |
Flaviviruses constitute a family of linear, single-stranded RNA(+) viruses. Flaviviruses include the West Nile virus, dengue virus, Tick-borne Encephalitis Virus, Yellow Fever Virus, and several other viruses. Many flavivirus species can replicate in both mammalian and insect cells. Most flaviviruses are arthropod borne and multiply in both vertebrates and arthropods. The viruses in this family that are of veterinary importance include Japanese encephalitis virus, St. Louis encephalitis virus, West Nile virus, Israel turkey meningoencephalomyelitis virus, Sitiawan virus, Wesselsbron virus, yellow fever virus and the tick-borne flaviviruses e.g. louping ill virus. | 1 | Applied and Interdisciplinary Chemistry |
The following panels show sea surface concentrations of fields prepared by GLODAPv1.1. The "pre-industrial" is the 18th century, while "present-day" is approximately the 1990s.
The following panels show sea surface concentrations of fields prepared by GLODAPv2. The "pre-industrial" is the 18th century, while "present-day" is normalised to 2002. Note that these properties are shown in mass units (per kilogram of seawater) rather than the volume units (per cubic metre of seawater) used in the GLODAPv1.1 panels. | 0 | Theoretical and Fundamental Chemistry |
Toluene disproportionation (TDP) is the conversion of toluene to benzene and xylene.
Given that demand for para-xylene (p-xylene) substantially exceeds demand for other xylene isomers, a refinement of the TDP process called Selective TDP (STDP) may be used. In this process, the xylene stream exiting the TDP unit is approximately 90% p-xylene. In some systems, even the benzene-to-xylenes ratio is modified to favor xylenes. | 1 | Applied and Interdisciplinary Chemistry |
Fasteners join, or affix, two or more objects. Although they are usually used to attach pipe and fittings to mechanical supports in buildings, they do not connect the pipes. Fasteners commonly used with piping are a stud bolt with nuts (usually fully threaded, with two heavy, hexagonal nuts); a machine bolt and nut; or a powder-actuated tool (PAT) fastener (usually a nail or threaded stud, driven into concrete or masonry). | 1 | Applied and Interdisciplinary Chemistry |
Flowers of sulfur (FOS) testing was developed to determine the porosity of metallic coatings susceptible to sulfur induced corrosion [see below ASTM B809-95(2018)]. Applicable substrates are silver, copper, copper alloys and any other metal or metal alloy with which sulfur will react. For porosity testing, coatings can be single or multiple layers of any metal that is not corroded and sealed by a self-limiting reaction in the reducing sulfur environment of the FOS test. The simplest recommended technique is to identify any porosity of the coating as revealed by the presence of surface spots. These surface spots form where the environmental sulfur has penetrated and reacted with the base metal, producing a metal sulfide. Chalcocite, copper (I) sulfide is dark-grey to black. Silver (I) sulfide is also grey-black.
The adoption of lead-free solders and lead-free soldering motivated the further development and application of immersion silver plating. Immersion silver improves wettability and solderability. Mixed flowing gas testing failed to alert the electronics manufacturing industry to weaknesses in immersion silver plating (for example, see Reference 7). This furthered the application of FOS. In particular, it was determined that moist, high-sulfur environments facilitated creep corrosion. The development of FOS testing for creep corrosion was furthered by efforts under the auspices of the International Electronics Manufacturing Initiative (INEMI) and the Surface Mount Technology Association (SMTA) by Haley Fu, et al. and Prabjit Singh et al. MFG testing also proved unreliable for high-sulfur environmental testing of chip resistors and their certification as sulfur resistant. There has been recent development in utilizing FOS testing for porosity of conformal coatings.
The material under test is suspended inside a container over a source of powdered sulfur. The powdered sulfur is placed in a dish. The temperature and internal humidity of the container are regulated. Temperature is typically controlled by placing the container in a constant temperature oven. Humidity inside the container is typically controlled with a saturated salt solution whose vapor pressure is well characterized at the temperature of the test. Saturated potassium nitrate solution is standard practice for humidity control in humid sulfur vapor testing. The saturated salt solution is placed physically outside of the sulfur containing dish. The sulfur containing dish may “float” in the saturated salt solution. The dish should provide an ample, available powdered sulfur surface.
Recommended materials for the test chamber are glass and acrylic. The materials under test must be suspended or supported above the saturated salt solution. Suspension materials are also recommended fabricated from glass or plastic. Frames made out of 316 stainless steel have seen use for hanging specimens. Monofilament line has been used for hanging objects under test. Recommended specimen placement is at least 75 mm from the surfaces of the sulfur and the saturated salt solutions, at least 25 mm from all internal vessel surfaces and at least 10 mm spacing from specimen to specimen.
Standard test procedures call for performing the specimen exposure at 50 °C for at least 24 hours. Activity of the sulfur and its products with humid air increase with temperature. Exposure periods can be extended into the week range. Decisions on length of exposure is commonly motivated by observations from shorter-term tests. Standard procedure calls for equilibrating the test chamber at temperature and relative humidity before inserting the test specimens.
Porosity results are determined by the distribution, number and sizes of dark spots on the materials under test. Again, the dark spots are due to reaction of the moist sulfur vapors with the underlying silver or copper material. One may choose to include silver or both silver and copper reference coupons into the humid sulfur test. The accumulation of copper(I) sulfate and silver (I) sulfate deposits on the coupons, determined by weight change, allows comparisons to ISA 71.04 severity levels for mixed flowing gas testing. | 1 | Applied and Interdisciplinary Chemistry |
Flotufolastat F-18, sold under the brand name Posluma, is a radioactive diagnostic agent for use with positron emission tomography (PET) imaging for prostate cancer. The active ingredient is flotufolastat F-18 gallium.
Flotufolastat F-18 was approved for medical use in the United States in May 2023. | 1 | Applied and Interdisciplinary Chemistry |
More generally, systems in equilibrium at temperature have probability of occupying a state with energy weighted by the corresponding Boltzmann factor:
where is the partition function. Again, it is the energy-like quantity that takes central importance.
Consequences of this include (in addition to the results for ideal gases above) the Arrhenius equation in chemical kinetics. | 0 | Theoretical and Fundamental Chemistry |
Isotopic effect expressed with the equations given above only refer to reactions that can be described with first-order kinetics. In all instances in which this is not possible, transient kinetic isotope effects should be taken into account using the GEBIK and GEBIF equations. | 0 | Theoretical and Fundamental Chemistry |
ATP is a molecule found in and around living cells, and as such it gives a direct measure of biological concentration and health. ATP is quantified by measuring the light produced through its reaction with the naturally occurring firefly enzyme luciferase using a luminometer. The amount of light produced is directly proportional to the amount of ATP present in the sample.
ATP tests can be used to:
* Control biological treatment reactors
* Guide biocide dosing programs
* Determine drinking water cleanliness
* Manage fermentation processes
* Assess soil activity
* Determine corrosion / deposit process type
* Measure equipment or product sanitation | 1 | Applied and Interdisciplinary Chemistry |
Solving for yields two solutions. They must both be analyzed to determine which is the physical solution. One will usually be a subsonic root and the other a supersonic root. If it is not clear which value of velocity is correct, the second law of thermodynamics may be applied.
Second law of thermodynamics:
The values and are unknown and may be dropped from the formulation. The value of entropy is not necessary, only that the value is positive.
One possible unreal solution for the stream thrust averaged velocity yields a negative entropy. Another method of determining the proper solution is to take a simple average of the velocity and determining which value is closer to the stream thrust averaged velocity. | 1 | Applied and Interdisciplinary Chemistry |
The microdialysis technique has undergone much development since its first use in 1972, when it was first employed to monitor concentrations of endogenous biomolecules in the brain. Today's area of application has expanded to monitoring free concentrations of endogenous as well as exogenous compounds in virtually any tissue. Although microdialysis is still primarily used in preclinical animal studies (e.g. laboratory rodents, dogs, sheep, pigs), it is now increasingly employed in humans to monitor free, unbound drug tissue concentrations as well as interstitial concentrations of regulatory cytokines and metabolites in response to homeostatic perturbations such as feeding and/or exercise.
When employed in brain research, microdialysis is commonly used to measure neurotransmitters (e.g. dopamine, serotonin, norepinephrine, acetylcholine, glutamate, GABA) and their metabolites, as well as small neuromodulators (e.g. cAMP, cGMP, NO), amino acids (e.g. glycine, cysteine, tyrosine), and energy substrates (e.g. glucose, lactate, pyruvate). Exogenous drugs to be analyzed by microdialysis include new antidepressants, antipsychotics, as well as antibiotics and many other drugs that have their pharmacological effect site in the brain. The first non-metabolite to be analyzed by microdialysis in vivo in the human brain was rifampicin.
Applications in other organs include the skin (assessment of bioavailability and bioequivalence of topically applied dermatological drug products), and monitoring of glucose concentrations in patients with diabetes (intravascular or subcutaneous probe placement). The latter may even be incorporated into an artificial pancreas system for automated insulin administration.
Microdialysis has also found increasing application in environmental research, sampling a diversity of compounds from waste-water and soil solution, including saccharides, metal ions, micronutrients, organic acids, and low molecular weight nitrogen. Given the destructive nature of conventional soil sampling methods, microdialysis has potential to estimate fluxes of soil ions that better reflect an undisturbed soil environment. | 1 | Applied and Interdisciplinary Chemistry |
Some sources claim that the first production of hydrofluoric acid was by Heinrich Schwanhard, a German glass cutter, in 1670. A peer-reviewed study of Schwanhard's writings, though, showed no specific mention of fluorite and only discussion of an extremely strong acid. It was hypothesized that this was probably nitric acid or aqua regia, both capable of etching soft glass.
Andreas Sigismund Marggraf made the first definite preparation of hydrofluoric acid in 1764 when he heated fluorite with sulfuric acid in glass, which was greatly corroded by the product. In 1771, Swedish chemist Carl Wilhelm Scheele repeated this reaction. Scheele recognized the product of the reaction as an acid, which he called "fluss-spats-syran" (fluor-spar-acid); in English, it was known as "fluoric acid". | 1 | Applied and Interdisciplinary Chemistry |
Tumor necrosis factor ligand superfamily member 9 also known as 4-1BB ligand or 4-1BBL or CD137L is a protein that in humans is encoded by the TNFSF9 gene.
4-1BBL is a type 2 transmembrane glycoprotein receptor that is found on APCs (antigen presenting cells) and binds to 4-1BB (also known as CD137). The 4-1BB/4-1BBL complex belongs to the TNFR:TNF superfamily, which is expressed on activated T Lymphocytes. | 1 | Applied and Interdisciplinary Chemistry |
In chemistry, "activation" refers to the reversible transition of a molecule into a nearly identical chemical or physical state, with the defining characteristic being that this resultant state exhibits an increased propensity to undergo a specified chemical reaction. Thus, activation is conceptually the opposite of protection, in which the resulting state exhibits a decreased propensity to undergo a certain reaction.
The energy of activation specifies the amount of free energy the reactants must possess (in addition to their rest energy) in order to initiate their conversion into corresponding products—that is, in order to reach the transition state for the reaction. The energy needed for activation can be quite small, and often it is provided by the natural random thermal fluctuations of the molecules themselves (i.e. without any external sources of energy).
The branch of chemistry that deals with this topic is called chemical kinetics. | 0 | Theoretical and Fundamental Chemistry |
Hard soaps (), also termed soda soaps in older terminology, are categorized under soaps and are typically sodium salts of fatty acids. They vary in color from white to brownish and have a fatty acid content ranging from 72 to 75%. These soaps are typically made from lower-quality fats. Hard soaps serve as the foundation for products frequently labeled as fine soaps, which are fortified with nourishing additives, perfumes, and dyes. | 0 | Theoretical and Fundamental Chemistry |
Background radiation equivalent time (BRET) or background equivalent radiation time (BERT) is a unit of measurement of ionizing radiation dosage amounting to one day worth of average human exposure to background radiation.
BRET units are used as a measure of low level radiation exposure. The health hazards of low doses of ionizing radiation are unknown and controversial, because the effects, mainly cancer and genetic damage, take many years to appear, and the incidence due to radiation exposure can't be statistically separated from the many other causes of these diseases. The purpose of the BRET measure is to allow a low level dose to be easily compared with a universal yardstick: the average dose of background radiation, mostly from natural sources, that every human unavoidably receives during daily life. Background radiation level is widely used in radiological health fields as a standard for setting exposure limits. Presumably, a dose of radiation which is equivalent to what a person would receive in a few days of ordinary life will not increase their rate of disease measurably. | 0 | Theoretical and Fundamental Chemistry |
; (2001 September); Magnum opus
Pereras Magnum opus never loses sight of what is required to make a complete cricketer – in every sense of the word. Former England skipper Mike Brearley OBE has contributed the preface while the then Sri Lankas cricket coach, Davenall Whatmore, the foreword. It is the only self study training guide by an umpire for the players. It has won admiration and gained much recognition to the country from the cricketing world, which includes the ICC, MCC, ECB and even the prestigious Wisden Cricketers' Almanack (2002).
;Further Reading
* [http://thinkingcricket2.tripod.com/THINKING%20CRICKET.htm Thinking Cricket (February 2004)] Retrieved on 12 March 2009
* [http://www.island.lk/2001/11/11/sports05.html This is no ordinary cricket book but a well-thought out book of instructions. By Mahinda Wijesinghe (2001 November)] Retrieved on 12 March 2009 | 0 | Theoretical and Fundamental Chemistry |
The European Fusion Development Agreement (EFDA) was created in 1999.
Until 2008 EFDA was responsible for the exploitation of the Joint European Torus, the coordination and support of fusion-related research & development activities carried out by the Associations and by European Industry and coordination of the European contribution to large scale international collaborations, such as the ITER-project.
2008 has brought a significant change to the structure of the European Fusion Programme. The change was triggered by the signature of the ITER agreement at the end of 2006. The ITER parties had agreed to provide contributions to ITER through legal entities referred to as "Domestic Agencies". Europe has fulfilled its obligation by launching the European Domestic Agency called "[http://fusionforenergy.europa.eu/ Fusion for Energy]", also called F4E, in March 2007.
With the appearance of F4E EFDA´s role has changed and it has been reorganised. A revised European Fusion Development Agreement entered into force on 1 January 2008 focuses on research coordination with two main objectives: to prepare for the operation and exploitation of ITER and to further develop and consolidate the knowledge base needed for overall fusion development and in particular for DEMO, the first electricity producing experimental fusion power plant being built after ITER. | 0 | Theoretical and Fundamental Chemistry |
Surface tension describes how difficult it is to extend the area of a surface (by stretching or distorting it). If surface tension is high, there is a large free energy required to increase the surface area, so the surface will tend to contract and hold together like a rubber sheet.
There are various factors affecting surface tension, one of which is that the composition of the surface may be different from the bulk. For example, if water is mixed with a tiny amount of surfactants (for example, hand soap), the bulk water may be 99% water molecules and 1% soap molecules, but the topmost surface of the water may be 50% water molecules and 50% soap molecules. In this case, the soap has a large and positive "surface excess". In other examples, the surface excess may be negative: For example, if water is mixed with an inorganic salt like sodium chloride, the surface of the water is on average less salty and more pure than the bulk average.
Consider again the example of water with a bit of soap. Since the water surface needs to have higher concentration of soap than the bulk, whenever the water's surface area is increased, it is necessary to remove soap molecules from the bulk and add them to the new surface. If the concentration of soap is increased a bit, the soap molecules are more readily available (they have higher chemical potential), so it is easier to pull them from the bulk in order to create the new surface. Since it is easier to create new surface, the surface tension is lowered. The general principle is:
:When the surface excess of a component is positive, increasing the chemical potential of that component reduces the surface tension.
Next consider the example of water with salt. The water surface is less salty than bulk, so whenever the waters surface area is increased, it is necessary to remove salt molecules from the new surface and push them into bulk. If the concentration of salt is increased a bit (raising the salts chemical potential), it becomes harder to push away the salt molecules. Since it is now harder to create the new surface, the surface tension is higher. The general principle is:
:When the surface excess of a component is negative, increasing the chemical potential of that component increases the surface tension.
The Gibbs isotherm equation gives the exact quantitative relationship for these trends. | 0 | Theoretical and Fundamental Chemistry |
Non-specific acting modes of toxic action result in narcosis; therefore, narcosis is a mode of toxic action. Narcosis is defined as a generalized depression in biological activity due to the presence of toxicant molecules in the organism. The target site and mechanism of toxic action through which narcosis affects organisms are still unclear, but there are hypotheses that support that it occurs through alterations in the cell membranes at specific sites of the membranes, such as the lipid layers or the proteins bound to the membranes. Even though continuous exposure to a narcotic toxicant can produce death, if the exposure to the toxicant is stopped, narcosis can be reversible. | 1 | Applied and Interdisciplinary Chemistry |
The role of electricity in the nervous systems of animals was first observed in dissected frogs by Luigi Galvani, who studied it from 1791 to 1797. Galvani's results inspired Alessandro Volta to develop the Voltaic pile—the earliest-known electric battery—with which he studied animal electricity (such as electric eels) and the physiological responses to applied direct-current voltages.
In the 19th century scientists studied the propagation of electrical signals in whole nerves (i.e., bundles of neurons) and demonstrated that nervous tissue was made up of cells, instead of an interconnected network of tubes (a reticulum). Carlo Matteucci followed up Galvanis studies and demonstrated that injured nerves and muscles in frogs could produce direct current. Matteuccis work inspired the German physiologist, Emil du Bois-Reymond, who discovered in 1843 that stimulating these muscle and nerve preparations produced a notable diminution in their resting currents, making him the first researcher to identify the electrical nature of the action potential. The conduction velocity of action potentials was then measured in 1850 by du Bois-Reymond's friend, Hermann von Helmholtz. Progress in electrophysiology stagnated thereafter due to the limitations of chemical theory and experimental practice. To establish that nervous tissue is made up of discrete cells, the Spanish physician Santiago Ramón y Cajal and his students used a stain developed by Camillo Golgi to reveal the myriad shapes of neurons, which they rendered painstakingly. For their discoveries, Golgi and Ramón y Cajal were awarded the 1906 Nobel Prize in Physiology. Their work resolved a long-standing controversy in the neuroanatomy of the 19th century; Golgi himself had argued for the network model of the nervous system.
The 20th century saw significant breakthroughs in electrophysiology. In 1902 and again in 1912, Julius Bernstein advanced the hypothesis that the action potential resulted from a change in the permeability of the axonal membrane to ions. Bernsteins hypothesis was confirmed by Ken Cole and Howard Curtis, who showed that membrane conductance increases during an action potential. In 1907, Louis Lapicque suggested that the action potential was generated as a threshold was crossed, what would be later shown as a product of the dynamical systems of ionic conductances. In 1949, Alan Hodgkin and Bernard Katz refined Bernsteins hypothesis by considering that the axonal membrane might have different permeabilities to different ions; in particular, they demonstrated the crucial role of the sodium permeability for the action potential. They made the first actual recording of the electrical changes across the neuronal membrane that mediate the action potential. This line of research culminated in the five 1952 papers of Hodgkin, Katz and Andrew Huxley, in which they applied the voltage clamp technique to determine the dependence of the axonal membrane's permeabilities to sodium and potassium ions on voltage and time, from which they were able to reconstruct the action potential quantitatively. Hodgkin and Huxley correlated the properties of their mathematical model with discrete ion channels that could exist in several different states, including "open", "closed", and "inactivated". Their hypotheses were confirmed in the mid-1970s and 1980s by Erwin Neher and Bert Sakmann, who developed the technique of patch clamping to examine the conductance states of individual ion channels. In the 21st century, researchers are beginning to understand the structural basis for these conductance states and for the selectivity of channels for their species of ion, through the atomic-resolution crystal structures, fluorescence distance measurements and cryo-electron microscopy studies.
Julius Bernstein was also the first to introduce the Nernst equation for resting potential across the membrane; this was generalized by David E. Goldman to the eponymous Goldman equation in 1943. The sodium–potassium pump was identified in 1957 and its properties gradually elucidated, culminating in the determination of its atomic-resolution structure by X-ray crystallography. The crystal structures of related ionic pumps have also been solved, giving a broader view of how these molecular machines work. | 0 | Theoretical and Fundamental Chemistry |
Modafinil is sold under a variety of brand names worldwide, including Alertec, Alertex, Altasomil, Aspendos, Bravamax, Forcilin, Intensit, Karim, Mentix, Modafinilo, Modalert, Modanil, Modasomil, Modvigil, Modiodal, Modiwake, Movigil, Provigil, Resotyl, Stavigile, Vigia, Vigicer, Vigil, Vigimax, Waklert, and Zalux. | 0 | Theoretical and Fundamental Chemistry |
Lateral flow assays have a wide array of applications and can test a variety of samples like urine, blood, saliva, sweat, serum, and other fluids. They are currently used by clinical laboratories, hospitals, and physicians for quick and accurate tests for specific target molecules and gene expression. Other uses for lateral flow assays are food and environmental safety and veterinary medicine for chemicals such as diseases and toxins. LFTs are also commonly used for disease identification such as ebola, but the most common LFT are the home pregnancy and SARS-CoV-2 tests. | 1 | Applied and Interdisciplinary Chemistry |
* 1900 – Hugo de Vries, Carl Correns and Erich von Tschermak independently rediscovered Mendel's paper on heredity.
* 1902 – Walter Sutton and Theodor Boveri, independently proposed that the chromosomes carry the hereditary information.
* 1905 – William Bateson coined the term "genetics" to describe the study of biological inheritance.
* 1906 – Mikhail Tsvet discovered the chromatography technique for organic compound separation.
* 1907 – Ivan Pavlov demonstrated conditioned responses with salivating dogs.
* 1907 – Hermann Emil Fischer artificially synthesized peptide amino acid chains and thereby shows that amino acids in proteins are connected by amino group-acid group bonds.
* 1909 – Wilhelm Johannsen coined the word "gene."
* 1911 – Thomas Hunt Morgan proposed that genes are arranged in a line on the chromosomes.
* 1922 – Aleksandr Oparin proposed that the Earth's early atmosphere contained methane, ammonia, hydrogen, and water vapor, and that these were the raw materials for the origin of life.
* 1926 – James B. Sumner showed that the urease enzyme is a protein.
* 1928 – Otto Diels and Kurt Alder discovered the Diels-Alder cycloaddition reaction for forming ring molecules.
* 1928 – Alexander Fleming discovered the first antibiotic, penicillin
* 1929 – Phoebus Levene discovered the sugar deoxyribose in nucleic acids.
* 1929 – Edward Doisy and Adolf Butenandt independently discovered estrone.
* 1930 – John Howard Northrop showed that the pepsin enzyme is a protein.
* 1931 – Adolf Butenandt discovered androsterone.
* 1932 – Hans Adolf Krebs discovered the urea cycle.
* 1933 – Tadeus Reichstein artificially synthesized vitamin C; first vitamin synthesis.
* 1935 – Rudolf Schoenheimer used deuterium as a tracer to examine the fat storage system of rats.
* 1935 – Wendell Stanley crystallized the tobacco mosaic virus.
* 1935 – Konrad Lorenz described the imprinting behavior of young birds.
* 1937 – Dorothy Crowfoot Hodgkin discovered the three-dimensional structure of cholesterol.
* 1937 – Hans Adolf Krebs discovered the tricarboxylic acid cycle.
* 1937 – In Genetics and the Origin of Species, Theodosius Dobzhansky applies the chromosome theory and population genetics to natural populations in the first mature work of neo-Darwinism, also called the modern synthesis, a term coined by Julian Huxley.
* 1938 – Marjorie Courtenay-Latimer discovered a living coelacanth off the coast of southern Africa.
* 1940 – Donald Griffin and Robert Galambos announced their discovery of echolocation by bats.
* 1942 – Max Delbrück and Salvador Luria demonstrated that bacterial resistance to virus infection is caused by random mutation and not adaptive change.
* 1944 – Oswald Avery shows that DNA carried the hereditary information in pneumococcus bacteria.
* 1944 – Robert Burns Woodward and William von Eggers Doering synthesized quinine.
* 1945 – Dorothy Crowfoot Hodgkin discovered the three-dimensional structure of penicillin.
* 1948 – Erwin Chargaff showed that in DNA the number of guanine units equals the number of cytosine units and the number of adenine units equals the number of thymine units. | 1 | Applied and Interdisciplinary Chemistry |
Calibration materials are compounds whose isotopic composition is known extremely well relative to the primary reference materials or which define the isotopic composition of the primary reference materials but are not the isotopic ratios to which data are reported in the scientific literature. For example, the calibration material IAEA-S-1 defines the isotopic scale for sulfur but measurements are reported relative to VCDT, not relative to IAEA-S-1. The calibration material serves the function of the primary reference material when the primary reference is exhausted, unavailable, or never existed in physical form. | 0 | Theoretical and Fundamental Chemistry |
In 1799, Benjamin Thompson (Count Rumford) had proposed the establishment in London of an Institution for Diffusing Knowledge, i.e. the Royal Institution. The house in Albemarle Street was bought in April 1799. Rumford became secretary to the institution, and Dr Thomas Garnett was the first lecturer.
In February 1801 Davy was interviewed by the committee of the Royal Institution, comprising Joseph Banks, Benjamin Thompson and Henry Cavendish. Davy wrote to Davies Giddy on 8 March 1801 about the offers made by Banks and Thompson, a possible move to London and the promise of funding for his work in galvanism. He also mentioned that he might not be collaborating further with Beddoes on therapeutic gases. The next day Davy left Bristol to take up his new post at the Royal Institution, it having been resolved that Humphry Davy be engaged in the service of the Royal Institution in the capacity of assistant lecturer in chemistry, director of the chemical laboratory, and assistant editor of the journals of the institution, and that he be allowed to occupy a room in the house, and be furnished with coals and candles, and that he be paid a salary of 100l. per annum.
On 25 April 1801, Davy gave his first lecture on the relatively new subject of Galvanism. He and his friend Coleridge had had many conversations about the nature of human knowledge and progress, and Davy's lectures gave his audience a vision of human civilisation brought forward by scientific discovery. "It [science] has bestowed on him powers which may almost be called creative; which have enabled him to modify and change the beings surrounding him, and by his experiments to interrogate nature with power, not simply as a scholar, passive and seeking only to understand her operations, but rather as a master, active with his own instruments." The first lecture garnered rave reviews, and by the June lecture Davy wrote to John King that his last lecture had attendance of nearly 500 people. "There was Respiration, Nitrous Oxide, and unbounded Applause. Amen!" Davy revelled in his public status. | 1 | Applied and Interdisciplinary Chemistry |
Tamiflu is a carbocyclic mimic of the cell-surface carbohydrate sialic acid. Tamiflu is an enzyme inhibitor that blocks the action of influenza virus neuraminidases (sialidases). | 1 | Applied and Interdisciplinary Chemistry |
According to Thomson Reuters in their 2012 publication "The Economic Power of Orphan Drugs", there has been increased investment in orphan drug research and development, partly due to the U.S. Orphan Drug Act of 1983 (ODA) and similar acts in other regions of the world driven by "high-profile philanthropic funding".
According to Drug Discovery Today, the years 2001 to 2011 were the "most productive period in the history of orphan drug development, in terms of average annual orphan drug designations and orphan drug approvals". For the same decade the compound annual growth rate (CAGR) of the orphan drugs was an "impressive 25.8%, compared to only 20.1% for a matched control group of non-orphan drugs". By 2012, the market for orphan drugs was worth US$637 million, compared with US$638 million for a control group of non-orphan drugs.
By 2012,
According to a 2014 report, the orphan drug market has become increasingly lucrative for a number of reasons. The cost of clinical trials for orphan drugs is substantially lower than for other diseases because trial sizes are naturally much smaller than for more diseases with larger numbers of patients. Small clinical trials and minimal competition place orphan agents at an advantage in regulatory review.
Tax incentives reduce the cost of development. On average the cost per patient for orphan drugs is "six times that of non-orphan drugs, a clear indication of their pricing power". The cost of per-person outlays are large and are expected to increase with wider use of public subsidies.
The 2014 Orphan Drug report stated that the percentage of orphan drug sales as part of all prescription drug sales had been increasing at a rapid rate. The report projected a total of US$176 billion by 2020. Although orphan disease populations are the smallest, the cost of per-patient outlays among them are the largest and are expected to increase as more people with rare diseases become eligible for subsidies – in the U.S., for example, through the Affordable Care Act. | 1 | Applied and Interdisciplinary Chemistry |
The superoxide ion, is generated in biological systems by reduction of molecular oxygen. It has an unpaired electron, so it behaves as a free radical. It is a powerful oxidizing agent. These properties render the superoxide ion very toxic and are deployed to advantage by phagocytes to kill invading microorganisms. Otherwise, the superoxide ion must be destroyed before it does unwanted damage in a cell. The superoxide dismutase enzymes perform this function very efficiently.
The formal oxidation state of the oxygen atoms is −. In solutions at neutral pH, the superoxide ion disproportionates to molecular oxygen and hydrogen peroxide.
:2 + 2 H → O + HO
In biology this type of reaction is called a dismutation reaction. It involves both oxidation and reduction of superoxide ions. The superoxide dismutase (SOD) group of enzymes increase the rate of reaction to near the diffusion-limited rate. The key to the action of these enzymes is a metal ion with variable oxidation state that can act either as an oxidizing agent or as a reducing agent.
:Oxidation: M + → M + O
:Reduction: M + + 2 H → M + HO.
In human SOD, the active metal is copper, as Cu(II) or Cu(I), coordinated tetrahedrally by four histidine residues. This enzyme also contains zinc ions for stabilization and is activated by copper chaperone for superoxide dismutase (CCS). Other isozymes may contain iron, manganese or nickel. The activity of Ni-SOD involves nickel(III), an unusual oxidation state for this element. The active site nickel geometry cycles from square planar Ni(II), with thiolate (Cys and Cys) and backbone nitrogen (His and Cys) ligands, to square pyramidal Ni(III) with an added axial His side chain ligand. | 1 | Applied and Interdisciplinary Chemistry |
COMOS is a plant engineering software from Siemens. The applications for this software are in the process industries for the engineering, operation, and maintenance of process plants as well as their asset management. | 1 | Applied and Interdisciplinary Chemistry |
Beltrami fields are a classical steady solution to the Euler equation. Beltrami fields play an important role in (ideal) fluid mechanics in equilibrium, as complexity is only expected for these fields. | 1 | Applied and Interdisciplinary Chemistry |
Emulsified Fuels are emulsions composed of water and a combustible liquid, either oil or a fuel. Emulsions are a particular example of a dispersion comprising a continuous and a dispersed phase. The most commonly used emulsion fuel is water-in-diesel emulsion. In the case of emulsions, both phases are the immiscible liquids, oil and water. Emulsion fuels can be either a microemulsion or an ordinary emulsion (sometimes referred to as macroemulsion, to differentiate it from microemulsion). The essential differences between the two are stability (microemulsions are thermodynamically stable systems, whereas macroemulsions are kinetically stabilized) and particle size distribution (microemulsions are formed spontaneously and have dimensions of 10 to 200 nm, whereas macroemulsions are formed by a shearing process and have dimensions of 100 nm to over 1 micrometer). Microemulsions are isotropic whereas macroemulsions are prone to settling (or creaming) and changes in particle size over time. Both use surfactants (also called emulsifiers) and can be either water-in-oil (invert emulsions), or oil-in-water (regular emulsions) or bicontinuous (also called multiple or complex emulsions). | 0 | Theoretical and Fundamental Chemistry |
The complex [Ru(o-CHPPh)(H)(CO)(PPh)] catalyzes the Murai reaction at room temperature. For [Ru(H)(H)(PR)], the active complex is [Ru(H)(PR)].
After the active form of the ruthenium catalyst complex is generated from 1, acetophenone coordinates to the complex via its carbonyl oxygen and agostically via its ortho C-H bond (2). As in the Ru proposed mechanism, this agostic interaction leads to the oxidative addition of the ortho C-H. Reductive elimination releases H, which remains coordinated, giving complex 3. Coordination of ethylene and decoordination of the ketone results in complex 4 which then undergoes migratory insertion of ethylene into the hydride to give 5. Following oxidative addition of H (6), the complex reductively eliminates the product to give the product agostically bound to the complex. Coordination of another acetophenone molecule regenerates complex 2. | 0 | Theoretical and Fundamental Chemistry |
Transition state structures can be determined by searching for first-order saddle points on the potential energy surface (PES) of the chemical species of interest. A first-order saddle point is a critical point of index one, that is, a position on the PES corresponding to a minimum in all directions except one. This is further described in the article geometry optimization. | 0 | Theoretical and Fundamental Chemistry |
Surfactants are usually organic compounds that are akin to amphiphilic, which means that this molecule, being as double-agent, each contains a hydrophilic "water-seeking" group (the head), and a hydrophobic "water-avoiding" group (the tail). As a result, a surfactant contains both a water-soluble component and a water-insoluble component. Surfactants diffuse in water and get adsorbed at interfaces between air and water, or at the interface between oil and water in the case where water is mixed with oil. The water-insoluble hydrophobic group may extend out of the bulk water phase into a non-water phase such as air or oil phase, while the water-soluble head group remains bound in the water phase.
The hydrophobic tail may be either lipophilic ("oil-seeking") or lipophobic ("oil-avoiding") depending on its chemistry. Hydrocarbon groups are usually lipophilic, for use in soaps and detergents, while fluorocarbon groups are lipophobic, for use in repelling stains or reducing surface tension.
World production of surfactants is estimated at 15 million tons per year, of which about half are soaps. Other surfactants produced on a particularly large scale are linear alkylbenzene sulfonates (1.7 million tons/y), lignin sulfonates (600,000 tons/y), fatty alcohol ethoxylates (700,000 tons/y), and alkylphenol ethoxylates (500,000 tons/y). | 0 | Theoretical and Fundamental Chemistry |
Metalworking is the process of shaping and reshaping metals to create useful objects, parts, assemblies, and large scale structures. As a term it covers a wide and diverse range of processes, skills, and tools for producing objects on every scale: from huge ships, buildings, and bridges down to precise engine parts and delicate jewelry.
The historical roots of metalworking predate recorded history; its use spans cultures, civilizations and millennia. It has evolved from shaping soft, native metals like gold with simple hand tools, through the smelting of ores and hot forging of harder metals like iron, up to highly technical modern processes such as machining and welding. It has been used as an industry, a driver of trade, individual hobbies, and in the creation of art; it can be regarded as both a science and a craft.
Modern metalworking processes, though diverse and specialized, can be categorized into one of three broad areas known as forming, cutting, or joining processes. Modern metalworking workshops, typically known as machine shops, hold a wide variety of specialized or general-use machine tools capable of creating highly precise, useful products. Many simpler metalworking techniques, such as blacksmithing, are no longer economically competitive on a large scale in developed countries; some of them are still in use in less developed countries, for artisanal or hobby work, or for historical reenactment. | 1 | Applied and Interdisciplinary Chemistry |
The thermodynamic square (also known as the thermodynamic wheel, Guggenheim scheme or Born square) is a mnemonic diagram attributed to Max Born and used to help determine thermodynamic relations. Born presented the thermodynamic square in a 1929 lecture. The symmetry of thermodynamics appears in a paper by F.O. Koenig. The corners represent common conjugate variables while the sides represent thermodynamic potentials. The placement and relation among the variables serves as a key to recall the relations they constitute.
A mnemonic used by students to remember the Maxwell relations (in thermodynamics) is "Good Physicists Have Studied Under Very Fine Teachers", which helps them remember the order of the variables in the square, in clockwise direction. Another mnemonic used here is "Valid Facts and Theoretical Understanding Generate Solutions to Hard Problems", which gives the letter in the normal left-to-right writing direction. Both times A has to be identified with F, another common symbol for Helmholtz free energy. To prevent the need for this switch the following mnemonic is also widely used:"Good Physicists Have Studied Under Very Ambitious Teachers"; another one is Good Physicists Have SUVAT, in reference to the equations of motion. One other useful variation of the mnemonic when the symbol E is used for internal energy instead of U is the following: "Some Hard Problems Go To Finish Very Easy". | 0 | Theoretical and Fundamental Chemistry |
Jeanette Grasselli Brown (born Jeanette Gecsy; August 4, 1928) is an American analytical chemist and spectroscopist who is known for her work with Standard Oil of Ohio (now BP America) as an industrial researcher in the field of spectroscopy.
Spectroscopy is a technique used to measure the interaction of electromagnetic radiation with matter. Her areas of expertise encompass fields such as vibrational spectroscopy, combined instrumental techniques, computerized spectroscopy, and environmental spectroscopy. She developed new techniques to solve problems like identifying contaminants in gasoline, analyzing the makeup of new plastics, and analyzing environmental problems such as pollution.
During her career, Grasselli Brown has striven to bridge the gap between research and practical applications between industry and academia. She is considered one of the foremost contributors to infrared and Raman spectrometry of the 20th century. | 0 | Theoretical and Fundamental Chemistry |
Latimer diagrams can be used in the construction of Frost diagrams, as a concise summary of the standard electrode potentials relative to the element. Since ΔG to HO, then from HO to HO) is the same as the Gibbs energy change for the overall reduction (i.e. from O to HO), in accordance with Hess's law. This can be used to find the electrode potential for non-adjacent steps, which gives all the information necessary for the Frost diagram.
A simple examination of a Latimer diagram can also indicate if a species will disproportionate in solution under the conditions for which the electrode potentials are given: if the potential to the right of the species is higher than the potential on the left, it will disproportionate. Therefore, hydrogen peroxide is unstable and will disproportionate (see diagram above). | 0 | Theoretical and Fundamental Chemistry |
Organometallic compounds containing mercury (e.g., thiomersal) and arsenic (e.g. Salvarsan) had a long history of use in medicine as nonselective antimicrobials before the advent of modern antibiotics.
Titanocene dichloride displays anti-cancer activity, and [[dichloridobis((p-methoxybenzyl)cyclopentadienyl)titanium|dichloridobis[(p-methoxybenzyl)cyclopentadienyl]titanium]] is a current anticancer drug candidate. Arene- and cyclopentadienyl complexes are kinetically inert platforms for the design of new radiopharmaceuticals.
Furthermore, there have been made studies utilizing exogenous semi-synthetic ligands; specifically to the dopamine transporter, observing increased resultant efficacy in regard to reward facilitating behavior (incentive salience) and habituation, namely with the phenyltropane compound [[List of phenyltropanes#η6-3β-(transition metal complexed phenyl)tropanes|[η-(2β-carbomethoxy-3β-phenyl)tropane]tricarbonylchromium]].
Carbon monoxide releasing organometallic compounds are also actively investigated, due to the importance of carbon monoxide as a gasotransmitter. | 0 | Theoretical and Fundamental Chemistry |
An excess of acid is called acidosis or acidemia, while an excess in bases is called alkalosis or alkalemia. The process that causes the imbalance is classified based on the cause of the disturbance (respiratory or metabolic) and the direction of change in pH (acidosis or alkalosis). This yields the following four basic processes: | 0 | Theoretical and Fundamental Chemistry |
In the 1996 report of the method, thin films were coated with yttrium and lanthanum topped with a layer of palladium for the diffusion of hydrogen. The rate of absorption of hydrogen resulted in typical optical properties. In the 2008 report magnesium, titanium and nickel are eroded and sputtering deposited in different ratios onto a transparent film in a thin layer of 100 nanometres following exposure to hydrogen in different amounts resulting in optical differences. | 0 | Theoretical and Fundamental Chemistry |
Xe has not been detected in Venus's atmosphere. Xe has an upper limit of 10 parts per billion by volume. The absence of data on the abundance of Xe precludes us from evaluating if the abundance of Xe is close to solar values or if there is Xe paradox on Venus. The lack also prevents us from checking if the isotopic composition has been mass dependently fractionated, as in the case of Earth and Mars. | 0 | Theoretical and Fundamental Chemistry |
*Pavel Drašar (Chair), University of Chemistry and Technology, Prague, Czech Republic
*Reiner Salzer (Vice-Chair), TU Dresden, Dresden, Germany
*Richard Whewell (Secretary 2008), Strathclyde University, Glasgow, Scotland, UK
*Evangelia Varella (Secretary 2008–2013), University of Thessaloniki, Thessaloniki, Greece
*a number of members | 1 | Applied and Interdisciplinary Chemistry |
Because most heterocyclic bases contain multiple nucleophilic sites, site selectivity is an important issue in nucleoside synthesis. Purine bases, for instance, react kinetically at N and thermodynamically at N (see Eq. (4)). Glycosylation of thymine with protected 1-acetoxy ribose produced 60% of the N nucleoside and 23% of the N nucleoside. Closely related triazines, on the other hand, react with complete selectivity to afford the N nucleoside.
The most nucleophilic nitrogen can be blocked through alkylation prior to nucleoside synthesis. Heating the blocked nucleoside in Eq. (6) in the presence of a protected sugar chloride provides the nucleoside in 59% yield. Reactions of this type are hampered by alkylation of the heterocycle by incipient alkyl chloride.
Silylated heterocyclic bases are susceptible to hydrolysis and somewhat difficult to handle as a result; thus, the development of a one-pot, one-step method for silylation and nucleoside synthesis represented a significant advance. The combination of trifluoroacetic acid (TFA), trimethylsilyl chloride (TMSCl), and hexamethyldisilazide (HMDS) generates trimethylsilyl trifluoroacetate in situ, which accomplishes both the silylation of the heterocycle and its subsequent coupling with the sugar. | 0 | Theoretical and Fundamental Chemistry |
When using a 10 mm path length, simply multiply the OD by the conversion factor to determine the concentration. Example, a 2.0 OD dsDNA sample corresponds to a sample with a 100 µg/ml concentration.
When using a path length that is shorter than 10mm, the resultant OD will be reduced by a factor of 10/path length. Using the example above with a 3 mm path length, the OD for the 100 µg/ml sample would be reduced to 0.6. To normalize the concentration to a 10mm equivalent, the following is done:
0.6 OD X (10/3) * 50 µg/ml=100 µg/ml
Most spectrophotometers allow selection of the nucleic acid type and path length such that resultant concentration is normalized to the 10 mm path length which is based on the principles of Beer's law. | 0 | Theoretical and Fundamental Chemistry |
Peripheral expression of cannabinoid receptors led researchers to investigate the role of cannabinoids in the autonomic nervous system. Research found that the CB receptor is expressed presynaptically by motor neurons that innervate visceral organs. Cannabinoid-mediated inhibition of electric potentials results in a reduction in noradrenaline release from sympathetic nervous system nerves. Other studies have found similar effects in endocannabinoid regulation of intestinal motility, including the innervation of smooth muscles associated with the digestive, urinary, and reproductive systems. | 1 | Applied and Interdisciplinary Chemistry |
Tear gas generally consists of aerosolized solid or liquid compounds (bromoacetone or xylyl bromide), not gas. Tear gas works by irritating mucous membranes in the eyes, nose, mouth and lungs. It causes crying, sneezing, coughing, difficulty breathing, pain in the eyes, and temporary blindness. With CS gas, symptoms of irritation typically appear after 20 to 60 seconds of exposure and commonly resolve within 30 minutes of leaving (or being removed from) the area. | 1 | Applied and Interdisciplinary Chemistry |
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