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Guldberg has found that a rough estimate of the normal boiling point T, when expressed in kelvins (i.e., as an absolute temperature), is approximately two-thirds of the critical temperature T. Lydersen uses this basic idea but calculates more accurate values. | 0 | Theoretical and Fundamental Chemistry |
Chiral ligands are useful for inducing asymmetry within the coordination sphere. Often the ligand is employed as an optically pure group. In some cases, such as secondary amines, the asymmetry arises upon coordination. Chiral ligands are used in homogeneous catalysis, such as asymmetric hydrogenation. | 0 | Theoretical and Fundamental Chemistry |
More accurate description of double layer interactions can be put forward on the primitive model. This model treats the electrostatic and hard-core interactions between all individual ions explicitly. However, it includes the solvent only in a "primitive" way, namely as a dielectric continuum. This model was studied in much detail in the theoretical community. Explicit expressions for the forces are mostly not available, but they are accessible with computer simulations, integral equations, or density functional theories.
The important finding from these studies is that the PB description represents only a mean-field approximation. This approximation is excellent in the so-called weak coupling regime, that is for monovalent electrolytes and weakly charged surfaces. However, this description breaks down in the strong coupling regime, which may be encountered for multivalent electrolytes, highly charged systems, or non-aqueous solvents. In the strong coupling regime, the ions are strongly correlated, meaning that each ion has an exclusion hole around itself. These correlations lead to strong ion adsorption to charged surfaces, which may lead to charge reversal and crystallization of these ions on the surface. These correlations may also induce attractive forces. The range of these forces is typically below 1 nm. | 0 | Theoretical and Fundamental Chemistry |
In 1996, he was highly commended by the then Sri Lanka Cricket Board in becoming of great assistance to them, as single-handedly, Perera accepted and satisfactorily completed its highly technical assignment to streamline the rules and regulations governing 2, 3 and 4-day Division – 1, Division – 2 and under 24 Major Tournament Cricket in Sri Lanka.
Seated on a Wheelchair, battling paraplegia and balancing a laptop, he even Authored Two A – 4 size Internationally famed books on Cricket, The Golden Era of Sri Lankan Cricket (May 1999) and Thinking Cricket (September 2001) . They were also Published by him without any external financial support.
In December 1999, at the request of the Sri Lanka Cricket Board, Perera designed and conducted over four half-days the FIRST Formal Training and Evaluation Programme for the top Sri Lanka Cricket Scorers, in preparation for the under-19 Cricket World Cup Tournament that was held in Sri Lanka in January 2000.
Perera has also turned a pioneer dis-Ability Activist campaigning in Sri Lanka for Accessible built Sports Environments for Al and user-friendly Facilities. | 0 | Theoretical and Fundamental Chemistry |
The process of mechanical alloying involves the production of a composite powder particles by:
# Using a high energy mill to favor plastic deformation required for cold welding and reduce the process times
# Using a mixture of elemental and master alloy powders (the latter to reduce the activity of the element, since it is known that the activity in an alloy or a compound could be orders of magnitude less than in a pure metal)
# Eliminating the use of surface-active agents which would produce fine pyrophoric powder as well as contaminate the powder
# Relying on a constant interplay between welding and fracturing to yield a powder with a refined internal structure, typical of very fine powders normally produced, but having an overall particle size which was relatively coarse, and therefore stable. | 1 | Applied and Interdisciplinary Chemistry |
These properties of the genetic code make it more fault-tolerant for point mutations. For example, in theory, fourfold degenerate codons can tolerate any point mutation at the third position, although codon usage bias restricts this in practice in many organisms; twofold degenerate codons can withstand silence mutation rather than Missense or Nonsense point mutations at the third position. Since transition mutations (purine to purine or pyrimidine to pyrimidine mutations) are more likely than transversion (purine to pyrimidine or vice versa) mutations, the equivalence of purines or that of pyrimidines at twofold degenerate sites adds a further fault-tolerance.
A practical consequence of redundancy is that some errors in the genetic code cause only a synonymous mutation, or an error that would not affect the protein because the hydrophilicity or hydrophobicity is maintained by equivalent substitution of amino acids (conservative mutation). For example, a codon of NUN (where N = any nucleotide) tends to code for hydrophobic amino acids, NCN yields amino acid residues that are small in size and moderate in hydropathy, and NAN encodes average size hydrophilic residues. These tendencies may result from the shared ancestry of the aminoacyl tRNA synthetases related to these codons.
These variable codes for amino acids are allowed because of modified bases in the first base of the anticodon of the tRNA, and the base-pair formed is called a wobble base pair. The modified bases include inosine and the Non-Watson-Crick U-G basepair. | 1 | Applied and Interdisciplinary Chemistry |
Hellmut Friedrich Fischmeister (14 May 1927 – 6 November 2019) was an Austrian metallurgist who was a pioneer in powder metallurgy. | 1 | Applied and Interdisciplinary Chemistry |
Boyle was born at Lismore Castle, in County Waterford, Ireland, the seventh son and fourteenth child of The 1st Earl of Cork (the Great Earl of Cork) and Catherine Fenton. Lord Cork, then known simply as Richard Boyle, had arrived in Dublin from England in 1588 during the Tudor plantations of Ireland and obtained an appointment as a deputy escheator. He had amassed enormous wealth and landholdings by the time Robert was born and had been created Earl of Cork in October 1620. Catherine Fenton, Countess of Cork, was the daughter of Sir Geoffrey Fenton, the former Secretary of State for Ireland, who was born in Dublin in 1539, and Alice Weston, the daughter of Robert Weston, who was born in Lismore in 1541.
As a child, Boyle was raised by a wet nurse, as were his elder brothers. Boyle received private tutoring in Latin, Greek, and French and when he was eight years old, following the death of his mother, he, and his brother Francis, were sent to Eton College in England. His father's friend, Sir Henry Wotton, was then the provost of the college.
During this time, his father hired a private tutor, Robert Carew, who had knowledge of Irish, to act as private tutor to his sons in Eton. However, "only Mr. Robert sometimes desires it [Irish] and is a little entered in it", but despite the "many reasons" given by Carew to turn their attentions to it, "they practice the French and Latin but they affect not the Irish". After spending over three years at Eton, Robert travelled abroad with a French tutor. They visited Italy in 1641 and remained in Florence during the winter of that year studying the "paradoxes of the great star-gazer", the elderly Galileo Galilei. | 1 | Applied and Interdisciplinary Chemistry |
Astrophysical fluid dynamics applies fluid dynamics and its equations to the movement of the fluids in space. The applications are different from regular fluid mechanics in that nearly all calculations take place in a vacuum with zero gravity.
Most of the interstellar medium is not at rest, but is in supersonic motion due to supernova explosions, stellar winds, radiation fields and a time dependent gravitational field caused by spiral density waves in the stellar discs of galaxies. Since supersonic motions almost always involve shock waves, shock waves must be accounted for in calculations. The galaxy also contains a dynamically significant magnetic field, meaning that the dynamics are governed by the equations of compressible magnetohydrodynamics. In many cases, the electrical conductivity is large enough for the ideal MHD equations to be a good approximation, but this is not true in star forming regions where the gas density is high and the degree of ionization is low. | 1 | Applied and Interdisciplinary Chemistry |
Single-photon emission computed tomography (SPECT) is a nuclear medicine imaging technique using gamma rays. It may be used with any gamma-emitting isotope, including Tc. In the use of technetium-99m, the radioisotope is administered to the patient and the escaping gamma rays are incident upon a moving gamma camera which computes and processes the image. To acquire SPECT images, the gamma camera is rotated around the patient. Projections are acquired at defined points during the rotation, typically every three to six degrees. In most cases, a full 360° rotation is used to obtain an optimal reconstruction. The time taken to obtain each projection is also variable, but 15–20 seconds are typical. This gives a total scan time of 15–20 minutes.
The technetium-99m radioisotope is used predominantly in bone and brain scans. For bone scans, the pertechnetate ion is used directly, as it is taken up by osteoblasts attempting to heal a skeletal injury, or (in some cases) as a reaction of these cells to a tumor (either primary or metastatic) in the bone. In brain scanning, Tc is attached to the chelating agent HMPAO to create technetium (Tc) exametazime, an agent which localizes in the brain according to region blood flow, making it useful for the detection of stroke and dementing illnesses that decrease regional brain flow and metabolism.
Most recently, technetium-99m scintigraphy has been combined with CT coregistration technology to produce SPECT/CT scans. These employ the same radioligands and have the same uses as SPECT scanning, but are able to provide even finer 3-D localization of high-uptake tissues, in cases where finer resolution is needed. An example is the sestamibi parathyroid scan which is performed using the Tc radioligand sestamibi, and can be done in either SPECT or SPECT/CT machines. | 0 | Theoretical and Fundamental Chemistry |
Fast Lic ( FLIC)
The computation can be significantly accelerated by re-using parts of already computed field lines, specializing to a box function as convolution kernel and avoiding redundant computations during convolution. The resulting fast LIC method can be generalized to convolution kernels that are arbitrary polynomials. | 1 | Applied and Interdisciplinary Chemistry |
*2023 Peter R. Griffiths
*2022 Martin Zanni
*2021 Rohit Bhargava
*2020 Volker Deckert
*2019 Ji-Xin Cheng
*2018 Peter Hamm
*2017 Roberto Merlin
*2016 Thomas Elsaesser
*2013 Xiaoliang Sunney Xie
*2012 Keith A. Nelson
*2011 Isao Noda
*2009 Michael D. Fayer
*2008 Richard P. Van Duyne
*2007 Jonathan Tennyson
*2006 Hai-Lung Dai
*2003 Shaul Mukamel
*2001 Lester Andrews
*2000 Donald Levy
*1999 Mitsuo Tasumi
*1998 Takeshi Oka
*1997 Robin Hochstrasser
*1995 Giacinto Scoles
*1994 Herbert L. Strauss
*1992 Richard Saykally
*1990 Robert W. Field
*1989 Marilyn E. Jacox
*1988 Andreas C. Albrecht
*1987 C. Bradley Moore
*1986 Wolfgang Kaiser
*1984 Jon T. Hougen
*1980 George C. Pimentel
*1979 E. Bright Wilson
*1978 Bryce L. Crawford, Jr.
*1976 Richard C. Lord | 0 | Theoretical and Fundamental Chemistry |
It has been observed that the stereoelectronic environment at the β-carbon of can also direct asymmetric induction. A number of predictive models have evolved over the years to define the stereoselectivity of such reactions. | 0 | Theoretical and Fundamental Chemistry |
In interferometric microscopy, the image of a micro-object is synthesized numerically as a coherent combination
of partial images with registered amplitude and phase.
For registration of partial images, a conventional holographic set-up is used with a reference wave, as is usual in optical holography. Capturing multiple exposures allows the numerical emulation of a large numerical aperture objective from images obtained with an objective lens with smaller-value numerical aperture.
Similar techniques allows scanning and precise detection of small particles.
As the combined image keeps both amplitude and phase information, the interferometric microscopy can be especially efficient for the phase objects, allowing detection of light variations of index of refraction, which cause the phase shift or the light passing through for a small fraction of a radian. | 0 | Theoretical and Fundamental Chemistry |
Liddle is known for his work on The Periodic Table of Videos, a series of videos from the University of Nottingham presented on YouTube, which feature educational vignettes on the periodic table.
He is executive producer for Chemistry at Manchester Explains Research Advances (CAMERA), a series of videos from the University of Manchester presented on YouTube, which feature videos explaining chemistry research papers published from the University of Manchester.
He is a National Co-ordinating Centre for Public Engagement Ambassador (2013–). | 0 | Theoretical and Fundamental Chemistry |
Chromatin immunoprecipitation (ChIP) techniques have been in use since 1984 to detect protein-DNA interactions. There have been many variations on ChIP to improve the quality of results. One such improvement, ChIP-on-chip (ChIP-chip), combines ChIP with microarray technology. This technique has limited sensitivity and specificity, especially in vivo where microarrays are constrained by thousands of proteins present in the nuclear compartment, resulting in a high rate of false positives. Next came ChIP-sequencing (ChIP-seq), which combines ChIP with high-throughput sequencing. However, the heterogeneous nature of sheared DNA fragments maps binding sites to within ±300 base pairs, limiting specificity. Secondly, contaminating DNA presents a grave problem since so few genetic loci are cross-linked to the protein of interest, making any non-specific genomic DNA a significant source of background noise.
To address these problems, Rhee and Pugh revised the classic nuclease protection assay to develop ChIP-exo. This new ChIP technique relies on a lambda exonuclease that degrades only, and all, unbound double-stranded DNA in the 5′-3′ direction. Briefly, a protein of interest (engineering one with an epitope tag can be useful for immunoprecipitation) is crosslinked in vivo to its natural binding locations across a genome using formaldehyde.
Cells are then collected, broken open, and the chromatin sheared and solubilized by sonication. An antibody is then used to immunoprecipitate the protein of interest, along with the crosslinked DNA. DNA PCR adaptors are then ligated to the ends, which serve as a priming point for second strand DNA synthesis after the exonuclease digestion. Lambda exonuclease then digests double DNA strands from the 5′ end until digestion is blocked at the border of the protein-DNA covalent interaction. Most contaminating DNA is degraded by the addition of a second single-strand specific exonuclease. After the cross-linking is reversed, the primers to the PCR adaptors are extended to form double stranded DNA, and a second adaptor is ligated to 5′ ends to demarcate the precise location of exonuclease digestion cessation. The library is then amplified by PCR, and the products are identified by high throughput sequencing. This method allows for resolution of up to a single base pair for any protein binding site within any genome, which is a much higher resolution than either ChIP-chip or ChIP-seq. | 1 | Applied and Interdisciplinary Chemistry |
1916 - A.M. Butlerov Small Prize of the Russian Physics and Chemistry Society (for the research on the composition of oil of plant species of the same family)
1953 - Order of Lenin
1954 - Prize of the D.I. Mendeleev All-Union Chemical Society | 0 | Theoretical and Fundamental Chemistry |
Fischer's lab team designed the material by building compounds made of individual copper and aluminum atoms. For this superatom, a mixture of aluminium atoms complexed with pentamethylcyclopentadiene (Cp*) and copper atoms complexed with mesitylene (Mes) were combined in an inert atmosphere.
:[AlCp*] + [CuMes] → [CuAl](Cp*)
After adding a solvent, the copper and aluminum atoms spontaneously separated from the organic compounds and formed the superatom cluster. The exergonic nature of the reaction demonstratesg that this specific arrangement of copper and aluminum atoms is stable. | 0 | Theoretical and Fundamental Chemistry |
The area of hypoxic bottom water that occurs for several weeks each summer in the Gulf of Mexico has been mapped most years from 1985 through 2017. The size varies annually from a record high in 2017 when it encompassed more than 22,730 square kilometers (8,776 square miles) to a record low in 1988 of 39 square kilometers (15 square miles). The 2015 dead zone measured 16,760 square kilometers (6,474 square miles).
Nancy Rabalais of the Louisiana Universities Marine Consortium in Cocodrie, Louisiana predicted the dead zone or hypoxic zone in 2012 will cover an area of 17,353 square kilometers (6,700 square miles) which is larger than Connecticut; however, when the measurements were completed, the area of hypoxic bottom water in 2012 only totaled 7,480 square kilometers. The models using the nitrogen flux from the Mississippi River to predict the "dead zone" areas have been criticized for being systematically high from 2006 to 2014, having predicted record areas in 2007, 2008, 2009, 2011, and 2013 that were never realized.
In late summer 1988 the dead zone disappeared as the great drought caused the flow of Mississippi to fall to its lowest level since 1933. During times of heavy flooding in the Mississippi River Basin, as in 1993, "the "dead zone"
dramatically increased in size, approximately larger than the previous year". | 0 | Theoretical and Fundamental Chemistry |
Amino acids are a key nutrient in ecosystems. Some are essential to animals, meaning that these organisms cannot synthesize them de novo. Instead, animals rely on their diet to acquire these molecules, creating strong interdependencies between animals and organisms with complete amino acid synthesis capabilities. In a study of bacteria and archaea at Antarctica's McMurdo Dry Valleys, the distribution of C between their amino acids reflected the biosynthetic pathways employed by these organisms. Autotrophs and heterotrophs had distinct isotopic fingerprints, as did organisms that employed alternatives to the citric acid cycle to ferment or produce acetate. Plants, fungi, and bacteria are also distinguishable by their amino acid carbon isotopes. The compositions of the essential amino acids, which have more complex biosynthetic pathways, are particularly informative. Lysine, isoleucine, leucine, threonine, and valine all had significantly different δC values between at least two of these groups. It is important to note that the fungi and bacteria in this study were grown on amino acid-free media to ensure that all the amino acids were synthesized by the organisms of interest. Bacteria and fungi can also scavenge amino acids from the environment, complicating the interpretation of data from field samples. Nevertheless, researchers have successfully used these differences to identify the sources of amino acids in food webs. Terrestrial and marine producers in a mangrove forest had different patterns of C enrichment in their amino acids. Fishes from a coral reef with diets containing different carbon sources also had variable amino acid δC values. Furthermore, one study observed distinct amino acid isotopic compositions for desert C, C, and CAM plants. These applications in diverse ecosystems highlight the versatility of compound-specific amino acid isotope analysis. | 0 | Theoretical and Fundamental Chemistry |
Strickland Landis Kneass was a civil engineer, experimenter, and author, with many accomplishments involving railroading. Kneass began publishing a mathematical model of the physics of the injector, which he had verified by experimenting with steam. A steam injector has three primary sections:
*Steam nozzle, a diverging duct, which converts high pressure steam to low pressure, high velocity steam
*Combining tube, a converging duct, which mixes high velocity steam and cold water
*Delivery tube, a diverging duct, where a high velocity stream of steam and cold water become a slow high pressure stream of water | 1 | Applied and Interdisciplinary Chemistry |
Gestonorone caproate was first described in 1960. It was developed by Schering and has been marketed since at least 1968. | 0 | Theoretical and Fundamental Chemistry |
Erwin Nick Hiebert (May 27, 1919 – November 28, 2012) was a Canadian-American physical chemist and professor of the history of science. He was the president of the History of Science Society for a two-year term from 1973 to 1974. | 0 | Theoretical and Fundamental Chemistry |
Pseudouridine, or Ψ, the overall most abundant post-translational RNA modification, is created when a uridine base is isomerised. In eukaryotes, this can occur by either of two distinct mechanisms; it is sometimes referred to as the ‘fifth RNA nucleotide’. It is incorporated into stable non-coding RNAs such as tRNA, rRNA, and snRNA, with roles in ribosomal ligand binding and translational fidelity in tRNA, and in fine-tuning branching events and splicing events in snRNAs. Pseudouridine has one more hydrogen bond donor from an imino group and a more stable C–C bond, since a C-glycosidic linkage has replaced the N-glycosidic linkage found in its counterpart (regular uridine). As neither of these changes affect its base-pairing properties, both will have the same output when directly sequenced; therefore methods for its detection involve prior biochemical modification. | 1 | Applied and Interdisciplinary Chemistry |
In an idealized system, all nuclei in a given chemical environment, in a magnetic field, precess with the same frequency. However, in real systems, there are minor differences in chemical environment which can lead to a distribution of resonance frequencies around the ideal. Over time, this distribution can lead to a dispersion of the tight distribution of magnetic spin vectors, and loss of signal (free induction decay). In fact, for most magnetic resonance experiments, this "relaxation" dominates. This results in dephasing.
However, decoherence because of magnetic field inhomogeneity is not a true "relaxation" process; it is not random, but dependent on the location of the molecule in the magnet. For molecules that aren't moving, the deviation from ideal relaxation is consistent over time, and the signal can be recovered by performing a spin echo experiment.
The corresponding transverse relaxation time constant is thus T, which is usually much smaller than T. The relation between them is:
where γ represents gyromagnetic ratio, and ΔB the difference in strength of the locally varying field.
Unlike T, T* is influenced by magnetic field gradient irregularities. The T* relaxation time is always shorter than the T relaxation time and is typically milliseconds for water samples in imaging magnets. | 0 | Theoretical and Fundamental Chemistry |
The electrical double layer can be regarded as behaving like a parallel plate capacitor with a compressible dielectric filling. When sound waves induce a local pressure variation, the spacing of the plates varies at the frequency of the excitation, generating an AC displacement current normal to the interface. For practical reasons this is most readily observed at a conducting surface. It is therefore possible to use an electrode immersed in a conducting electrolyte as a microphone, or indeed as a loudspeaker when the effect is applied in reverse. | 0 | Theoretical and Fundamental Chemistry |
Titan tholins are nitrogen-rich organic substances produced by the irradiation of the gaseous mixtures of nitrogen and methane found in the atmosphere and surface of Titan. Titan's atmosphere is about 97% nitrogen, 2.7±0.1% methane and the remaining trace amounts of other gases. In the case of Titan, the haze and orange-red color of its atmosphere are both thought to be caused by the presence of tholins. | 0 | Theoretical and Fundamental Chemistry |
Tyrocinium Chymicum was a published set of chemistry lecture notes started by Jean Beguin in 1610 in Paris, France. It has been cited as the first chemistry textbook (as opposed to that for alchemy). Many of the preparations were pharmaceutical in nature. | 1 | Applied and Interdisciplinary Chemistry |
In order to conduct DNA separation by silica adsorption, a sample (this may be anything from purified cells to a tissue specimen) is lysed, releasing proteins, DNA, phospholipids, etc. from the cells. The remaining tissue is discarded. The supernatant containing the DNA is then exposed to silica in a solution with high ionic strength. The highest DNA adsorption efficiencies occur in the presence of buffer solution with a pH at or below the pKa of the surface silanol groups.
The mechanism behind DNA adsorption onto silica is not fully understood; one possible explanation involves reduction of the silica surface's negative charge due to the high ionic strength of the buffer. This decrease in surface charge leads to a decrease in the electrostatic repulsion between the negatively charged DNA and the negatively charged silica. Meanwhile, the buffer also reduces the activity of water by formatting hydrated ions. This leads to the silica surface and DNA becoming dehydrated. These conditions lead to an energetically favorable situation for DNA to adsorb to the silica surface.
A further explanation of how DNA binds to silica is based on the action of guanidinium chloride (GuHCl), which acts as a chaotrope. A chaotrope denatures biomolecules by disrupting the shell of hydration around them. This allows positively charged ions to form a salt bridge between the negatively charged silica and the negatively charged DNA backbone in high salt concentration. The DNA can then be washed with high salt and ethanol, and ultimately eluted with low salt.
After the DNA is bound to the silica it is then washed to remove contaminants and finally eluted using an elution buffer or distilled water. | 1 | Applied and Interdisciplinary Chemistry |
may be used in combination with vibrational spectroscopy techniques to understand the origins of vibrations within crystals. The combination of techniques provides detailed information about crystal structures, similar to what can be achieved with x-ray crystallography. In addition to using computational methods for enhancing the understanding of spectroscopic data, the latest development in identifying polymorphism in crystals is the field of . This technique uses computational chemistry to model the formation of crystals and predict the existence of specific polymorphs of a compound before they have been observed experimentally by scientists. | 0 | Theoretical and Fundamental Chemistry |
The human asialoglycoprotein receptors composed of two units, H1 and H2. Each of these units have their N-terminus within the cytoplasm of a liver cell, and a carbohydrate recognition domain (CRD) on the extracellular side. The CRD functions to bind to asialoglycoproteins through a calcium ion-mediated interaction. In particular, the hydroxyl groups of the terminal sugars (usually galactose) of the asialoglycoprotein form hydrogen bonds with the CRD of the asialoglycoprotein receptor; proper positioning and facilitation of these hydrogen bonds is caused by the presence of Ca2+. | 1 | Applied and Interdisciplinary Chemistry |
D. C. Grahame modified the Stern model in 1947. He proposed that some ionic or uncharged species can penetrate the Stern layer, although the closest approach to the electrode is normally occupied by solvent molecules. This could occur if ions lose their solvation shell as they approach the electrode. He called ions in direct contact with the electrode "specifically adsorbed ions". This model proposed the existence of three regions. The inner Helmholtz plane (IHP) passes through the centres of the specifically adsorbed ions. The outer Helmholtz plane (OHP) passes through the centres of solvated ions at the distance of their closest approach to the electrode. Finally the diffuse layer is the region beyond the OHP. | 0 | Theoretical and Fundamental Chemistry |
For diamagnetic molecules at moderate field strengths, molecules have little preference in orientation, the tumbling samples a nearly isotropic distribution, and average dipolar couplings goes to zero. Actually, most molecules have preferred orientations in the presence of a magnetic field, because most have anisotropic magnetic susceptibility tensors, Χ.
The method is most suitable for systems with large values for magnetic susceptibility tensor. This includes: Protein-nucleic acid complex, nucleic acids, proteins with large number of aromatic residues, porphyrin containing proteins and metal binding proteins (metal may be replaced by lanthanides).
For a fully oriented molecule, the dipolar coupling for an H-N amide group would be over 20 kHz, and a pair of protons separated by 5 Å would have up to ~1 kHz coupling. However the degree of alignment achieved by applying magnetic field is so low that the largest H-N or H-C dipolar couplings are <5 Hz. Therefore, many different alignment media have been designed:
*Lipid bicelles (with large magnetic susceptibility): measured RDCs were of the order of hundreds of Hz.
*Liquid crystalline bicelles: measured RDCs were between -40 and +20 Hz.
*Rod-shaped viruses, including filamentous bacteriophage (large anisotropic magnetic susceptibility).
*DNA nanotubes (compatible with detergents used to solubilize membrane proteins) | 0 | Theoretical and Fundamental Chemistry |
If the underlying infertility is related to abnormalities in spermatogenesis, it is plausible, but too early to examine that male offspring are at higher risk for sperm abnormalities.
IVF does not seem to confer any risks regarding cognitive development, school performance, social functioning, and behaviour. Also, IVF infants are known to be as securely attached to their parents as those who were naturally conceived, and IVF adolescents are as well-adjusted as those who have been naturally conceived.
Limited long-term follow-up data suggest that IVF may be associated with an increased incidence of hypertension, impaired fasting glucose, increase in total body fat composition, advancement of bone age, subclinical thyroid disorder, early adulthood clinical depression and binge drinking in the offspring. It is not known, however, whether these potential associations are caused by the IVF procedure in itself, by adverse obstetric outcomes associated with IVF, by the genetic origin of the children or by yet unknown IVF-associated causes. Increases in embryo manipulation during IVF result in more deviant fetal growth curves, but birth weight does not seem to be a reliable marker of fetal stress.
IVF, including ICSI, is associated with an increased risk of imprinting disorders (including Prader–Willi syndrome and Angelman syndrome), with an odds ratio of 3.7 (95% confidence interval 1.4 to 9.7).
An IVF-associated incidence of cerebral palsy and neurodevelopmental delay are believed to be related to the confounders of prematurity and low birthweight. Similarly, an IVF-associated incidence of autism and attention-deficit disorder are believed to be related to confounders of maternal and obstetric factors.
Overall, IVF does not cause an increased risk of childhood cancer. Studies have shown a decrease in the risk of certain cancers and an increased risks of certain others including retinoblastoma, hepatoblastoma and rhabdomyosarcoma. | 1 | Applied and Interdisciplinary Chemistry |
Strained cyclooctenes and other activated alkenes react with tetrazines in an inverse electron-demand Diels-Alder followed by a retro [4+2] cycloaddition (see figure). Like the other reactions of the trans-cyclooctene, ring strain release is a driving force for this reaction. Thus, three-membered and four-membered cycloalkenes, due to their high ring strain, make ideal alkene substrates.
Similar to other [4+2] cycloadditions, electron-donating substituents on the dienophile and electron-withdrawing substituents on the diene accelerate the inverse-demand Diels-Alder. The diene, the tetrazine, by virtue of having the additional nitrogens, is a good diene for this reaction. The dienophile, the activated alkene, can often be attached to electron-donating alkyl groups on target molecules, thus making the dienophile more suitable for the reaction. | 0 | Theoretical and Fundamental Chemistry |
In molecular biology, an interactome is the whole set of molecular interactions in a particular cell. The term specifically refers to physical interactions among molecules (such as those among proteins, also known as protein–protein interactions, PPIs; or between small molecules and proteins) but can also describe sets of indirect interactions among genes (genetic interactions).
The word "interactome" was originally coined in 1999 by a group of French scientists headed by Bernard Jacq. Mathematically, interactomes are generally displayed as graphs. Though interactomes may be described as biological networks, they should not be confused with other networks such as neural networks or food webs. | 1 | Applied and Interdisciplinary Chemistry |
These two pathways, with the same effect on RuBisCO, evolved a number of times independently – indeed, C alone arose 62 times in 18 different plant families. A number of pre-adaptations seem to have paved the way for C, leading to its clustering in certain clades: it has most frequently developed in plants that already had features such as extensive vascular bundle sheath tissue. Whole-genome and individual gene duplication are also associated with C evolution. Many potential evolutionary pathways resulting in the phenotype are possible and have been characterised using Bayesian inference, confirming that non-photosynthetic adaptations often provide evolutionary stepping stones for the further evolution of .
The C construction is most famously used by a subset of grasses, while CAM is employed by many succulents and cacti. The trait appears to have emerged during the Oligocene, around ; however, they did not become ecologically significant until the Miocene, . Remarkably, some charcoalified fossils preserve tissue organised into the Kranz anatomy, with intact bundle sheath cells, allowing the presence C metabolism to be identified without doubt at this time. Isotopic markers are used to deduce their distribution and significance.
C plants preferentially use the lighter of two isotopes of carbon in the atmosphere, C, which is more readily involved in the chemical pathways involved in its fixation. Because C metabolism involves a further chemical step, this effect is accentuated. Plant material can be analysed to deduce the ratio of the heavier C to C. This ratio is denoted . C plants are on average around 14‰ (parts per thousand) lighter than the atmospheric ratio, while C plants are about 28‰ lighter. The of CAM plants depends on the percentage of carbon fixed at night relative to what is fixed in the day, being closer to C plants if they fix most carbon in the day and closer to C plants if they fix all their carbon at night.
It is troublesome procuring original fossil material in sufficient quantity to analyse the grass itself, but fortunately there is a good proxy: horses. Horses were globally widespread in the period of interest, and browsed almost exclusively on grasses. There's an old phrase in isotope palæontology, "you are what you eat (plus a little bit)" – this refers to the fact that organisms reflect the isotopic composition of whatever they eat, plus a small adjustment factor. There is a good record of horse teeth throughout the globe, and their has been measured. The record shows a sharp negative inflection around , during the Messinian, and this is interpreted as the rise of C plants on a global scale. | 0 | Theoretical and Fundamental Chemistry |
Biogas is a renewable energy that is a byproduct of the anaerobic digestion process.
Treated effluent can be used for agricultural or landscape irrigation. | 1 | Applied and Interdisciplinary Chemistry |
Foams can form following the degradation of harmful algal blooms (HABs). These are primarily composed of algal species, but can also consist of dinoflagellates and cyanobacteria. Biomass from algae in the bloom is integrated into sea foam in the sea surface microlayer. When the impacted sea foam breaks down, toxins from the algae are released into the air causing respiratory issues and occasionally initiating asthma attacks. Phaeocystis globosa is one algal species that is considered problematic, as observed in a study in the Netherlands. Its high biomass accumulation allows it to create large quantities of toxic foam that often wash onto beaches. P. globosa blooms are initiated in areas of high nutrient availability, often affiliated with coastal locations with a lot of stormwater runoff and eutrophication. Studies suggest that the development of foam is directly correlated to blooms caused by P. globosa, despite that foam formation typically occurs approximately two weeks after the appearance of an algal bloom offshore. Organic material from P. globosa was observed decomposing while suspended at the sea surface, but was not observed lower in the water column. P. globosa is also considered a nuisance species because its large foam formations impair the public's ability to enjoy the beach. | 0 | Theoretical and Fundamental Chemistry |
In the context of scattering light on extended bodies, the scattering cross section, , describes the likelihood of light being scattered by a macroscopic particle. In general, the scattering cross section is different from the geometrical cross section of a particle, as it depends upon the wavelength of light and the permittivity in addition to the shape and size of the particle. The total amount of scattering in a sparse medium is determined by the product of the scattering cross section and the number of particles present. In terms of area, the total cross section () is the sum of the cross sections due to absorption, scattering, and luminescence:
The total cross section is related to the absorbance of the light intensity through the Beer–Lambert law, which says that absorbance is proportional to concentration: , where is the absorbance at a given wavelength , is the concentration as a number density, and is the path length. The extinction or absorbance of the radiation is the logarithm (decadic or, more usually, natural) of the reciprocal of the transmittance : | 0 | Theoretical and Fundamental Chemistry |
Gadolinium is given to patients for magnetic resonance imaging, or an MRI.It is used as a contrast agent for the exam to improve clarity of the images formed. However, it can react in the human body and have detrimental effects. Therefore, the agent should be removed. One of these gadolinium based agents is gadodiamide. Calcium in the body should be determined accurately to ensure that the Gadodiamide does not have adverse effects on the patient. There are two o-cresolphthalein methods to determine amount of calcium. The o-cresolpthalein methods are effective because it is a calcium binding dye. The gadolinium ion with a charge of +3 can be removed from gadodiamide using o-cresolphthalein. For these methods, glomerular filtration rate, or GFR, and time since gadodiamide was given should be recorded. Ultimately, these two factors and the impact of gadodiamide on calcium levels calculated by the o-cresolphthalein method helps to reveal an amount of time that patients must wait after receiving gadodiamide to have blood drawn again, or avoid pseudohypocalcemia. | 0 | Theoretical and Fundamental Chemistry |
Uzer has more than 80 referenced Journal articles, in a number of highly respected scientific journals.
* [http://link.aps.org/abstract/PRE/v48/p3414 appeared in PRE] Chaotic billiards with neutral boundaries
* [http://www.sciencemag.org/cgi/content/abstract/253/5015/42 appeared in Science] Celestial Mechanics on a Microscopic Scale
* [http://link.aip.org/link/?JCPSA6/81/5013/1 appeared in JCP] Quantization with operators appropriate to shapes of trajectories and classical perturbation theory | 0 | Theoretical and Fundamental Chemistry |
Stable and transient transfection differ in their long term effects on a cell; a stably transfected cell will continuously express transfected DNA and pass it on to daughter cells, while a transiently transfected cell will express transfected DNA for a short amount of time and not pass it on to daughter cells.
For some applications of transfection, it is sufficient if the transfected genetic material is only transiently expressed. Since the DNA introduced in the transfection process is usually not integrated into the nuclear genome, the foreign DNA will be diluted through mitosis or degraded. Cell lines expressing the Epstein–Barr virus (EBV) nuclear antigen 1 (EBNA1) or the SV40 large-T antigen allow episomal amplification of plasmids containing the viral EBV (293E) or SV40 (293T) origins of replication, greatly reducing the rate of dilution.
If it is desired that the transfected gene actually remain in the genome of the cell and its daughter cells, a stable transfection must occur. To accomplish this, a marker gene is co-transfected, which gives the cell some selectable advantage, such as resistance towards a certain toxin. Some (very few) of the transfected cells will, by chance, have integrated the foreign genetic material into their genome. If the toxin is then added to the cell culture, only those few cells with the marker gene integrated into their genomes will be able to proliferate, while other cells will die. After applying this selective stress (selection pressure) for some time, only the cells with a stable transfection remain and can be cultivated further.
Common agents for selecting stable transfection are:
* Geneticin, or G418, neutralized by the product of the neomycin resistance gene
* Puromycin
* Zeocin
* Hygromycin B
* Blasticidin S | 1 | Applied and Interdisciplinary Chemistry |
A rheometer is a laboratory device used to measure the way in which a viscous fluid (a liquid, suspension or slurry) flows in response to applied forces. It is used for those fluids which cannot be defined by a single value of viscosity and therefore require more parameters to be set and measured than is the case for a viscometer. It measures the rheology of the fluid.
There are two distinctively different types of rheometers. Rheometers that control the applied shear stress or shear strain are called rotational or shear rheometers, whereas rheometers that apply extensional stress or extensional strain are extensional rheometers.
Rotational or shear type rheometers are usually designed as either a native strain-controlled instrument (control and apply a user-defined shear strain which can then measure the resulting shear stress) or a native stress-controlled instrument (control and apply a user-defined shear stress and measure the resulting shear strain). | 1 | Applied and Interdisciplinary Chemistry |
The GFP comprises 7 regional sections, covering different geographical areas of France (Grand Ouest, Nord, Ile de France, Est, Rhône-Alpes-Auvergne, Méditerranée, Sud Ouest). Each section elects a president who participates in the Administrative Council of the GFP. Organisation of national events (the Colloque national and JEPO) rotates between the sections, while each section organises local events. | 1 | Applied and Interdisciplinary Chemistry |
Formally, the Department of Chemistry has been created as a separate entity of Saint Petersburg State University (then Leningrad State University) in 1929. However, the history of chemistry at Saint Petersburg State University began much earlier. First chemistry laboratory and lectures in chemistry were introduced at the University in 1833. Many Russian chemists began their career and/or worked there. Among them are Nikolay Zinin, Alexey Favorsky, Lev Aleksandrovich Chugaev, Sergei Vasiljevich Lebedev, Vyacheslav Tishchenko, Vladimir Ipatieff, Nikolay Semyonov, Boris Nikolsky, Mikhail Shultz. In the Soviet era, the Department of Chemistry continued to grow with new divisions: colloid chemistry (1939), electrochemistry (1940), chemistry of macromolecular compounds (1944), radiochemistry (1945), physical organic chemistry (1946), theory of solutions (1950), chemistry of natural compounds (1963), quantum chemistry (1967), solid state chemistry (1978). | 1 | Applied and Interdisciplinary Chemistry |
Linear triatomic molecules owe their geometry to their sp or spd hybridised central atoms. Well-known linear triatomic molecules include carbon dioxide (CO) and hydrogen cyanide (HCN).
Xenon difluoride (XeF) is one of the rare examples of a linear triatomic molecule possessing non-bonded pairs of electrons on the central atom. | 0 | Theoretical and Fundamental Chemistry |
Boronic esters are oxidized to the corresponding alcohols with base and hydrogen peroxide (for an example see: carbenoid) | 0 | Theoretical and Fundamental Chemistry |
Fatty acid oxidation also occurs in peroxisomes when the fatty acid chains are too long to be processed by the mitochondria. The same enzymes are used in peroxisomes as in the mitochondrial matrix and acetyl-CoA is generated. Very long chain (greater than C-22) fatty acids, branched fatty acids, some prostaglandins and leukotrienes undergo initial oxidation in peroxisomes until octanoyl-CoA is formed, at which point it undergoes mitochondrial oxidation.
One significant difference is that oxidation in peroxisomes is not coupled to ATP synthesis. Instead, the high-potential electrons are transferred to O, which yields hydrogen peroxide. The enzyme catalase, found primarily in peroxisomes and the cytosol of erythrocytes (and sometimes in mitochondria), converts the hydrogen peroxide into water and oxygen.
Peroxisomal β-oxidation also requires enzymes specific to the peroxisome and to very long fatty acids. There are four key differences between the enzymes used for mitochondrial and peroxisomal β-oxidation:
# The NADH formed in the third oxidative step cannot be reoxidized in the peroxisome, so reducing equivalents are exported to the cytosol.
# β-oxidation in the peroxisome requires the use of a peroxisomal carnitine acyltransferase (instead of carnitine acyltransferase I and II used by the mitochondria) for transport of the activated acyl group into the mitochondria for further breakdown.
# The first oxidation step in the peroxisome is catalyzed by the enzyme acyl-CoA oxidase.
# The β-ketothiolase used in peroxisomal β-oxidation has an altered substrate specificity, different from the mitochondrial β-ketothiolase.
Peroxisomal oxidation is induced by a high-fat diet and administration of hypolipidemic drugs like clofibrate. | 1 | Applied and Interdisciplinary Chemistry |
Initial CO injection rates in the Weyburn field amounted to ~5,000 tonnes/day or 95 million scf/day (2.7 million m3/d); this would otherwise have been vented to the atmosphere from the Dakota Gasification facility. At one point, CO injection by Cenovus at Weyburn was at ~6,500 tonnes per day. Apache Canada is injecting approximately 1,500 tonnes/day into the Midale field.
Overall, it is anticipated that some 40 Mt of carbon dioxide will be permanently sequestered over the lifespan of the project in the Weyburn and Midale fields. The gas is being supplied via a 320 kilometre mile long pipeline (completed in 1999) from the lignite-fired Dakota Gasification Company synfuels plant site in Beulah, North Dakota (See attached image). The company is a subsidiary of Basin Electric Power Co-operative. At the plant, CO is produced from a Rectisol unit in the gas cleanup train. The CO project adds about $30 million of gross revenue to the gasification plant's cash flow each year. Approximately 8000 tonnes/day of compressed CO (in liquid form) is provided to the Weyburn and Midale fields via the pipeline.
During its life, the Weyburn and Midale fields combined are expected to produce at least 220 million additional barrels of incremental oil, through miscible or near-miscible displacement with CO, from a fields that have already produced over since discovery in 1954. This will extend the life of the Weyburn field by approximately 20–25 years. It is estimated that ultimate oil recovery will increase to 34% of the oil-in-place. It has been estimated that, on a full life-cycle basis, the oil produced at Weyburn by CO EOR will release only two-thirds as much CO to the atmosphere compared to oil produced using conventional technology.
This is the first instance of cross-border transfer of CO from the US to Canada and highlights the ability for international cooperation with GHG mitigation technologies. Whilst there are emissions trading projects being developed within countries such as Canada, the Weyburn project is essentially the first international project where physical quantities of CO are being sold commercially for enhanced oil recovery, with the added benefit of carbon sequestration. | 1 | Applied and Interdisciplinary Chemistry |
Structure field maps (SFMs) or structure maps are visualizations of the relationship between ionic radii and crystal structures for representing classes of materials. The SFM and its extensions has found broad applications in geochemistry, mineralogy, chemical synthesis of materials, and nowadays in materials informatics. | 0 | Theoretical and Fundamental Chemistry |
Although a number of surrogate biomarkers exist for measuring the metabolic products of bone resorption, the serum CTX marker was chosen because it is both highly correlated to bone turnover rate and already available for detection in a laboratory test carried out by a major lab testing corporation.
The CTX test measures for the presence and concentration of a crosslink peptide sequence of type I collagen, found, among other tissues, in bone. This specific peptide sequence relates to bone turnover because it is the portion that is cleaved by osteoclasts during bone resorption, and its serum levels are therefore proportional to osteoclastic activity at the time the blood sample is drawn. Serum levels in healthy patients not taking bisphosphonates tends to hover above 300 pg/mL.
Patients who are placed on a 6-month drug holiday exhibit marked improvements in their serum CTX values; in one study, patients showed an improvement of 155.3 pg/mL over 6 months or a rate of 25.9 pg/mL each month.
Initially, urinary CTX levels were sought, but this proved to offer no greater value than urinary NTX values—both tests suffered from large spontaneous fluctuations unrelated to therapy or intervention, and were therefore largely unreliable. In contrast, the monoclonal antibody test for detecting serum CTX levels features minimal spontaneous disruption yet remarkable change to antiresorptive therapy, making the serum CTX assay both highly sensitive and specific. | 1 | Applied and Interdisciplinary Chemistry |
JAKs range from 120-140 kDa in size and have seven defined regions of homology called Janus homology domains 1 to 7 (JH1-7). JH1 is the kinase domain important for the enzymatic activity of the JAK and contains typical features of a tyrosine kinase such as conserved tyrosines necessary for JAK activation (e.g., Y1038/Y1039 in JAK1, Y1007/Y1008 in JAK2, Y980/Y981 in JAK3, and Y1054/Y1055 in Tyk2). Phosphorylation of these dual tyrosines leads to the conformational changes in the JAK protein to facilitate binding of substrate. JH2 is a "pseudokinase domain", a domain structurally similar to a tyrosine kinase and essential for a normal kinase activity, yet lacks enzymatic activity. This domain may be involved in regulating the activity of JH1, and was likely a duplication of the JH1 domain which has undergone mutation post-duplication. The JH3-JH4 domains of JAKs share homology with Src-homology-2 (SH2) domains. The amino terminal (NH) end (JH4-JH7) of Jaks is called a FERM domain (short for band 4.1, ezrin, radixin and moesin); this domain is also found in the focal adhesion kinase (FAK) family and is involved in association of JAKs with cytokine receptors and/or other kinases. | 1 | Applied and Interdisciplinary Chemistry |
Failures due to service or operation conditions includes using a component outside of its intended conditions, such as an impact force or a high load. It can also include failures due to unexpected conditions in usage, such as an unexpected contact point that causes wear and abrasion or an unexpected humidity level or chemical presence that causes corrosion. These factors result in the component failing at an earlier time than expected. | 1 | Applied and Interdisciplinary Chemistry |
Exorphins can cause various symptoms of schizophrenia if mutation occurs at a few selected loci. Genetic mutation at one of these loci can lead to increased absorption of exorphins via receptor mediated endocytosis. Another possibility from these particular loci is that catabolization of exorphins can be disrupted thus allowing the exorphin to persist in the body. This would lead to exorphins entering the brain capillary, bypassing the blood brain barrier, and inflicting negative repercussion on the brain. This does not mean that exorphin will necessarily cause schizophrenia, as susceptibility to the disease is dependent on an individual's genetic makeup. However, by increasing the probability that exorphins enter the brain, it will also increase the chance of an individual displaying schizophrenic symptoms. | 1 | Applied and Interdisciplinary Chemistry |
* Ebrey, Walthall, Palais (2006). East Asia: A Cultural, Social, and Political History. Boston: Houghton Mifflin Company.
* Needham, Joseph (1986). Science and Civilization in China: Volume 4, Part 2; Needham, Joseph (1986). Science and Civilization in China: Volume 4, Part 3. | 1 | Applied and Interdisciplinary Chemistry |
Aziridine is an organic compound consisting of the three-membered heterocycle . It is a colorless, toxic, volatile liquid that is of significant practical interest. Aziridine was discovered in 1888 by the chemist Siegmund Gabriel. Its derivatives, also referred to as aziridines, are of broader interest in medicinal chemistry. | 0 | Theoretical and Fundamental Chemistry |
The National Radon Action Plan, also known as NRAP, was created in 2014 and launched in 2015. It is led by The American Lung Association with collaborative efforts from the American Association of Radon Scientists and Technologists, American Society of Home Inspectors, Cancer Survivors Against Radon, Children's Environmental Health Network, Citizens for Radioactive Radon Reduction, Conference of Radiation Control Program Directors, Environmental Law Institute, National Center for Healthy Housing, U.S. Environmental Protection Agency, U.S. Department of Health and Human Services, and U.S. Department of Housing and Urban Development. The goals of NRAP are to continue efforts set forth by FRAP to eliminate radon induced cancer that can be prevented by expanding radon testing, mitigating high levels of radon exposure, and developing radon resistant construction. NRAP also aims to reduce radon risk in 5 million homes, and save 3,200 lives by 2020. To complete these goals, representatives from each organization have established the following action plans: embed radon risk reduction as a standard practice across housing sectors, provide incentives and support to test and mitigate radon, promote the use of certified radon services and build the industry, and increase public attention to radon risk and the importance of reduction. The NRAP is currently in action, implementing programs, identifying approaches, and collaborating across organizations to achieve these goals. | 1 | Applied and Interdisciplinary Chemistry |
Similar to the polar sensitivity factor, the steric sensitivity factor δ for a new reaction series will describe to what magnitude the reaction rate is influenced by steric effects. When a reaction series is not significantly influenced by polar effects, the Taft equation reduces to:
A plot of the ratio of the rates versus the E value for the substituent will give a straight line with a slope equal to δ. Similarly to the Hammett ρ value, the magnitude of δ will reflect to what extent a reaction is influenced by steric effects:
*A very steep slope will correspond to high steric sensitivity, while a shallow slope will correspond to little to no sensitivity.
Since E values are large and negative for bulkier substituents, it follows that:
*If δ is positive, increasing steric bulk decreases the reaction rate and steric effects are greater in the transition state.
*If δ is negative, increasing steric bulk increases the reaction rate and steric effects are lessened in the transition state. | 0 | Theoretical and Fundamental Chemistry |
A thermodynamic system consisting of a single phase, in the absence of external forces, in its own state of internal thermodynamic equilibrium, is homogeneous. This means that the material in any region of the system can be interchanged with the material of any congruent and parallel region of the system, and the effect is to leave the system thermodynamically unchanged. The thermodynamic operation of scaling is the creation of a new homogeneous system whose size is a multiple of the old size, and whose intensive variables have the same values. Traditionally the size is stated by the mass of the system, but sometimes it is stated by the entropy, or by the volume. For a given such system , scaled by the real number to yield a new one , a state function, , such that , is said to be extensive. Such a function as is called a homogeneous function of degree 1. There are two different concepts mentioned here, sharing the same name: (a) the mathematical concept of degree-1 homogeneity in the scaling function; and (b) the physical concept of the spatial homogeneity of the system. It happens that the two agree here, but that is not because they are tautologous. It is a contingent fact of thermodynamics. | 0 | Theoretical and Fundamental Chemistry |
Nitrogen nucleophiles include ammonia, azide, amines, nitrites, hydroxylamine, hydrazine, carbazide, phenylhydrazine, semicarbazide, and amide. | 0 | Theoretical and Fundamental Chemistry |
The concept of an acid–base reaction was first proposed in 1754 by Guillaume-François Rouelle, who introduced the word "base" into chemistry to mean a substance which reacts with an acid to give it solid form (as a salt). Bases are mostly bitter in nature. | 0 | Theoretical and Fundamental Chemistry |
The H function can be approximated up to an order as
where are the zeros of Legendre polynomials and are the positive, non vanishing roots of the associated characteristic equation
where are the quadrature weights given by | 0 | Theoretical and Fundamental Chemistry |
9-Crown-3, also called 1,4,7-trioxonane or 1,4,7-trioxacyclononane is a crown ether with the formula (CHO). A colorless liquid, it is obtained in low yield by the acid-catalyzed oligomerization of ethylene oxide.
In contrast to larger crown ethers (12-crown-4, and 18-crown-6), 9-crown-3 has elicited very little interest, except from theorists. | 0 | Theoretical and Fundamental Chemistry |
Chloromethane, also called methyl chloride, Refrigerant-40, R-40 or HCC 40, is an organic compound with the chemical formula . One of the haloalkanes, it is a colorless, sweet-smelling, flammable gas. Methyl chloride is a crucial reagent in industrial chemistry, although it is rarely present in consumer products, and was formerly utilized as a refrigerant. Most chloromethane is biogenic. | 1 | Applied and Interdisciplinary Chemistry |
The Petasis reagent, named after Nicos A. Petasis, is an organotitanium compound with the formula CpTi(CH). It is an orange-colored solid. | 0 | Theoretical and Fundamental Chemistry |
Ethylene – π
In the most simple linear π systems, bonding to metals takes place by two interactions. Electron density is donated directly to the metal like a sigma bond would be formed. Also, the metal can donate electron density back to the linear π system (ethylene) from the metal's d orbital to the empty π* orbital of ethylene.
Allyl–π
Allyl groups can bond to metals as trihapto or monohapto ligands. Monohapto ligands bind mostly sigma orbitals and trihapto ligands bind using delocalized π orbitals. In essence the monohapto ligand binds the metal as an allyl group and the trihapto ligand binds over all three carbons, where the lowest energy π orbital donates electron density and the highest energy π orbital accepts electron density.
The allyl complex is diverse because it can alter the metal's electron count by transferring between a monohapto (1 electron, η) and trihapto ligand (3 electrons, η). This fluctuation allows stability when a two-electron-donating group bonds or breaks from the metal. | 0 | Theoretical and Fundamental Chemistry |
Copper(II) borate can be prepared by heating a stoichiometric mixture of copper(II) oxide and diboron trioxide to 900 °C. | 0 | Theoretical and Fundamental Chemistry |
*1960–61 – Fulbright–Smith–Mundt Fellowship
*1962–63 – Harrison Fellowship at University of Pennsylvania
*1986 – Guggenheim Fellowship
*2000 – Sir Edward Frankland Prize Lectureship
*2009 – Invited Lectureship, 4th Mitsui International Catalysis Symposium (MICS-4), Kisarazu, Japan
*2010 – Order of Culture
*2010 – Person of Cultural Merit
*2011 – Sagamore of the Wabash
*2011 – Order of the Griffin, Purdue University
*2011 – Fellow, American Academy of Arts & Sciences
*2011 – Honorary doctor of science, University of Pennsylvania.
*2012 – Honorary Fellow of Royal Society of Chemistry (RSC)
*2014 – Foreign Associate of the National Academy of Sciences | 0 | Theoretical and Fundamental Chemistry |
Samy El-Shall (Mohamed Samy El-Shall) is an Egyptian-American physical chemist and a researcher in nanoscience, heterogeneous catalysis, molecular clusters and cluster ions, nucleation and ion mobility. He is the Mary Eugenia Kapp Endowed Chair in Chemistry and Commonwealth Professor at Virginia Commonwealth University (VCU). | 0 | Theoretical and Fundamental Chemistry |
Gas in scattering media absorption spectroscopy (GASMAS) is an optical technique for sensing and analysis of gas located within porous and highly scattering solids, e.g. powders, ceramics, wood, fruit, translucent packages, pharmaceutical tablets, foams, human paranasal sinuses etc. It was introduced in 2001 by Prof. Sune Svanberg and co-workers at Lund University (Sweden). The technique is related to conventional high-resolution laser spectroscopy for sensing and spectroscopy of gas (e.g. tunable diode laser absorption spectroscopy, TDLAS), but the fact that the gas here is "hidden" inside solid materials give rise to important differences. | 0 | Theoretical and Fundamental Chemistry |
PDE3a expression has been described as a biomarker for sensitivity for PDE3-inhibitor Zardaverine in different types of cancer. | 1 | Applied and Interdisciplinary Chemistry |
Digital genetic sequences may be analyzed using the tools of bioinformatics to attempt to determine its function. | 1 | Applied and Interdisciplinary Chemistry |
A reaction mixture
containing 1 ml of 0.05% O-Phenanthroline in methanol, 2 ml ferric chloride (200 M) and 2 ml of various concentrations ranging from 10 to 1000 g was incubated at room temperature for 10 min and the absorbance of the same was measured at 510 nm. EDTA was used as a classical metal chelator. The experiment was performed in triplicates. The ferric reducing activity of date seed extract was estimated based on the method of Benzie and Strain (1999). The FRAP reagent was prepared by mixing 50 ml of acetate buffer (0.3 M) at pH 3.6, 5 ml of tripyridyltriazine (TPTZ) solution 10 mM prepared in HCl (40 mM) and 5 ml of ferric chloride solution (FeCl) (20 mM). 2 ml of the freshly prepared FRAP reagent was added to 10 lL of the extract. Then the absorbance was measured at 593 nm against the blank after 10 min at room temperature. The standard curve was constructed using Trolox. The result was expressed as Trolox equivalent in mg/100 g of dry weight (DW) date seed. | 1 | Applied and Interdisciplinary Chemistry |
A vortex is a region where the fluid flows around an imaginary axis.
For an irrotational vortex, the flow at every point is such that a small particle placed there undergoes pure translation and does not rotate.
Velocity varies inversely with radius in this case. Velocity will tend to at that is the reason for center being a singular point. The velocity is mathematically expressed as –
Since the fluid flows around an axis,
The stream function for irrotational vortices is given by –
While the velocity potential is expressed as –
For the closed curve enclosing origin, circulation (line integral of velocity field) and for any other closed curves, | 1 | Applied and Interdisciplinary Chemistry |
Effect of turbulence on dispersion – turbulence increases the entrainment and mixing of unpolluted air into the plume and thereby acts to reduce the concentration of pollutants in the plume (i.e., enhances the plume dispersion). It is therefore important to categorize the amount of atmospheric turbulence present at any given time. This type of dispersion is scale dependent. Such that, for flows where the cloud of pollutant is smaller than the largest eddies present, there will be mixing. There is no limit on the size on mixing motions in the atmosphere and therefore bigger clouds will experience larger and stronger mixing motions. And hence, this type of dispersion is scale dependent. | 1 | Applied and Interdisciplinary Chemistry |
Vincenzo Balzani (born 15 November 1936 in Forlimpopoli, Italy) is an Italian chemist, now emeritus professor at the University of Bologna. | 0 | Theoretical and Fundamental Chemistry |
Human neuraminidase (hNEU) shares many similar features with vNEU. The human genome has four different neuraminidase enzymes (NEU1, NEU2, NEU3, NEU4) and only one of them (NEU2) is not membrane-associated or in a membrane-complex and has been studied with X-ray crystallography. The three arginine residues that bind the C1 acid-group with salt bridges in vNEU are also present in hNEU. Active site topology and interactions with the substrate are very similar with the exception of the glycerol side chain which offers some strategic options in designing inhibitors targeting either vNEU or hNEU. In hNEU the glycerol hydroxyl-groups are bound via several tyrosine residues but in vNEU the main interaction is with a glutamic acid residue. These overall similarities have called for concerns over potential side effects from drugs targeting vNEU. Nevertheless, most of the well studied vNEU inhibitors have shown very little affinity for hNEU except for the influenza drug Zanamivir which is an effective inhibitor for hNEU2. | 1 | Applied and Interdisciplinary Chemistry |
Chemical analysis typically involves sampling some part of the environment and using lab equipment to figure out how much of a certain target compound exists. Chemical analysis may be used to assess pollution levels for remediation, or to make sure groundwater is safe for drinking.
Biological surveys typically includes a measurement of the abundance of a certain species within a certain area to confirm information about the ecosystem for specific reasons. Analysis like this could be used in efforts to understand species abundance, or to look at how external effects from the environment are affecting an ecosystem.
Soil tests may involve chemical analysis, but most often soil tests involve removing a section of soil to understand what each layer of soil is composed of for specific reasons. Soil samples might be needed when determining whether they can build on a certain site, or just to produce a model of an area, or to determine possible crop production considering nutrient levels.
Vegetation surveys are quite similar to a biosurvey, it's the process of measuring the abundance of plant species and trees within a specific area to understand more about the ecosystem for specific reasons. Sometimes these are done to understand ecological effects from outside factors, or to just determine overall ecosystem health.
Remote sensing can be used for environmental analysis by taking imagery shot by satellites in multiple wavelengths to assess areas of different scales for a certain objective. Remote sensing can be used to identify land use, it can be used to determine damages from forest fires, it can be used for weather systems and meteorology, and also for atmospheric composition. Recent advances in remote sensing field has also led to the development of autonomous devices for the analysis of physical and chemical parameters of the environment using the sensors. | 0 | Theoretical and Fundamental Chemistry |
Researching jelly-falls relies on direct observational data such as video, photography, or benthic trawls. A complication with trawling for jelly-falls is the gelatinous carcass easily falls apart and as a result, opportunistic photography, videography, and chemical analysis have been primary methods of monitoring. This means that jelly-falls are not always observed in the time period in which they exist. Because jelly-falls can be fully processed and degraded within a number of hours by scavengers and the fact that some jelly-falls will not sink below 500 m in tropical and subtropical waters, the importance and prevalence of jelly-falls may be underestimated. | 0 | Theoretical and Fundamental Chemistry |
Photonic crystals allow precise control of electromagnetic wave properties. These materials give rise to the photonic bandgap (PBG). In the spectral range of the PBG, electromagnetic waves cannot propagate. Engineering these materials allows some ability to tailor their emission and absorption properties, allowing for more effective emitter design. Selective emitters with peaks at higher energy than the black body peak (for practical TPV temperatures) allow for wider bandgap converters. These converters are traditionally cheaper to manufacture and less temperature sensitive. Researchers at Sandia Labs predicted a high-efficiency (34% of light emitted converted to electricity) based on TPV emitter demonstrated using tungsten photonic crystals. However, manufacturing of these devices is difficult and not commercially feasible. | 0 | Theoretical and Fundamental Chemistry |
An implant is a medical device manufactured to replace a missing biological structure, support a damaged biological structure, or enhance an existing biological structure. For example, an implant may be a rod, used to strengthen weak bones. Medical implants are human-made devices, in contrast to a transplant, which is a transplanted biomedical tissue. The surface of implants that contact the body might be made of a biomedical material such as titanium, silicone, or apatite depending on what is the most functional. In 2018, for example, American Elements developed a nickel alloy powder for 3D printing robust, long-lasting, and biocompatible medical implants. In some cases implants contain electronics, e.g. artificial pacemaker and cochlear implants. Some implants are bioactive, such as subcutaneous drug delivery devices in the form of implantable pills or drug-eluting stents. | 1 | Applied and Interdisciplinary Chemistry |
In diazo transfer certain carbon acids react with tosyl azide in the presence of a weak base like triethylamine or DBU. The byproduct is the corresponding tosylamide (p-toluenesulfonamide). This reaction is also called the Regitz diazo transfer. Examples are the synthesis of tert-butyl diazoacetate and diazomalonate. Methyl phenyldiazoacetate is generated in this way by treating methyl phenylacetate with p-acetamidobenzenesulfonyl azide in the presence of base.
The mechanism involves attack of the enolate at the terminal nitrogen, proton transfer, and expulsion of the anion of the sulfonamide. Use of the β-carbonyl aldehyde leads to a deformylative variant of the Regitz transfer, which is useful for the preparation of diazo compounds stabilized by only one carbonyl group. | 0 | Theoretical and Fundamental Chemistry |
Commercial tanning services are banned in all states, except the Northern Territory where no salons are in operation. Private ownership of tanning beds is permitted. | 0 | Theoretical and Fundamental Chemistry |
In Kinematical theory an approximation is made that the electrons are only scattered once. For transmission electron diffraction it is common to assume a constant thickness , and also what is called the Column Approximation (e.g. references and further reading). For a perfect crystal the intensity for each diffraction spot is then:<math display="block">I_{g} = \left|\phi(\mathbf k)\right|^2 \propto \left|F_{g}\frac{\sin(\pi t s_z)}{\pi s_z}\right|^2
is the magnitude of the excitation error along z, the distance along the beam direction (z-axis by convention) from the diffraction spot to the Ewald sphere, and is the structure factor:the sum being over all the atoms in the unit cell with the form factors, the reciprocal lattice vector, is a simplified form of the Debye–Waller factor, and is the wavevector for the diffraction beam which is:for an incident wavevector of , as in Figure 6 and above. The excitation error comes in as the outgoing wavevector has to have the same modulus (i.e. energy) as the incoming wavevector . The intensity in transmission electron diffraction oscillates as a function of thickness, which can be confusing; there can similarly be intensity changes due to variations in orientation and also structural defects such as dislocations. If a diffraction spot is strong it could be because it has a larger structure factor, or it could be because the combination of thickness and excitation error is "right". Similarly the observed intensity can be small, even though the structure factor is large. This can complicate interpretation of the intensities. By comparison, these effects are much smaller in x-ray diffraction or neutron diffraction because they interact with matter far less and often Bragg's law is adequate.
This form is a reasonable first approximation which is qualitatively correct in many cases, but more accurate forms including multiple scattering (dynamical diffraction) of the electrons are needed to properly understand the intensities. | 0 | Theoretical and Fundamental Chemistry |
Lithium burning is a nucleosynthetic process in which lithium is depleted in a star. Lithium is generally present in brown dwarfs and not in older low-mass stars. Stars, which by definition must achieve the high temperature (2.5 × 10 K) necessary for fusing hydrogen, rapidly deplete their lithium. | 0 | Theoretical and Fundamental Chemistry |
Due to defining molecule-framework interactions, COFs can be used as chemical sensors in a wide range of environments and applications. Properties of the COF change when their functionalities interact with various analytes enabling the materials to serve as devices in various conditions: as chemiresistive sensors, as well as electrochemical sensors for small molecules. | 0 | Theoretical and Fundamental Chemistry |
The first pass through the hepatic portal vein results in some of the drug being metabolized by O-demethylation into an active metabolite of dextromethorphan called dextrorphan, the 3-hydroxy derivative of dextromethorphan. The therapeutic activity of dextromethorphan is believed to be caused by both the drug and this metabolite. Dextromethorphan also undergoes N-demethylation (to 3-methoxymorphinan or MEM), and partial conjugation with glucuronic acid and sulfate ions. Hours after dextromethorphan therapy, (in humans) the metabolites (+)-3-hydroxy-N-methylmorphinan, (+)-3-morphinan, and traces of the unchanged drug are detectable in the urine.
A major metabolic catalyst involved is the cytochrome P450 enzyme known as 2D6, or CYP2D6. A significant portion of the population has a functional deficiency in this enzyme and are known as poor CYP2D6 metabolizers. O-demethylation of dextromethorphan to dextrorphan contributes to at least 80% of the dextrorphan formed during dextromethorphan metabolism. As CYP2D6 is a major metabolic pathway in the inactivation of dextromethorphan, the duration of action and effects of dextromethorphan can be increased by as much as three times in such poor metabolizers. In one study on 252 Americans, 84.3% were found to be "fast" (extensive) metabolizers, 6.8% to be "intermediate" metabolizers, and 8.8% were "slow" metabolizers of dextromethorphan. A number of alleles for CYP2D6 are known, including several completely inactive variants. The distribution of alleles is uneven amongst ethnic groups.
A large number of medications are potent inhibitors of CYP2D6. Some types of medications known to inhibit CYP2D6 include certain SSRIs and tricyclic antidepressants, some antipsychotics, and the commonly available antihistamine diphenhydramine. Therefore, the potential of interactions exists between dextromethorphan and medications that inhibit this enzyme, particularly in slow metabolizers.
Dextromethorphan is also metabolized by CYP3A4. N-demethylation is primarily accomplished by CYP3A4, contributing to at least 90% of the MEM formed as a primary metabolite of dextromethorphan.
A number of other CYP enzymes are implicated as minor pathways of dextromethorphan metabolism. CYP2D6 is more effective than CYP3A4 at N-demethylation of dextromethorphan, but since the average individual has a much lower CYP2D6 content in the liver compared to CYP3A4, most N-demethylation of dextromethorphan is catalyzed by CYP3A4. | 0 | Theoretical and Fundamental Chemistry |
Most H-NMR experiments with deuterated phospholipids demonstrate that the presence of proteins has little effect on either the order parameter of the lipids in the bilayer or the lipid dynamics, as measured by relaxation times. The overall view resulting from NMR experiments is 1) that the exchange rate between boundary and free lipids is rapid, (10 sec), 2) that the order parameters of the bound lipid are barely affected by being adjacent to proteins, 3) that the dynamics of the acyl chain reorientations are slowed only slightly in the frequency range of 10 sec, and 4) that the orientation and the dynamics of the polar headgroups are similarly unaffected in any substantial manner by being adjacent to transmembrane proteins. 13C-NMR spectrum also gives information on specific lipid-protein interactions of biomembranes
Recent results using non labeled optical methods such as Dual Polarisation Interferometry which measure the birefringence(or order) within lipid bilayers have been used to show how peptide and protein interactions can influence bilayer order, specifically demonstrating the real time association to bilayer and critical peptide concentration after which the peptides penetrate and disrupt the bilayer order. | 1 | Applied and Interdisciplinary Chemistry |
* Lehrbuch der Stereochemie . Fischer, Jena 1904 [http://nbn-resolving.de/urn:nbn:de:hbz:061:2-19527 Digital edition] by the University and State Library Düsseldorf | 0 | Theoretical and Fundamental Chemistry |
Mass cytometry has research applications in medical fields including immunology, hematology, and oncology. It has been used in studies of hematopoiesis, cell cycle, cytokine expression, and differential signaling responses.
MC has been used in various research fields, such as cancer biology, immunology, and neuroscience, to provide a more comprehensive understanding of tissue architecture and cellular interactions. | 0 | Theoretical and Fundamental Chemistry |
In organic chemistry, cyclopentanonide is a functional group which is composed of a cyclic ketal of a diol with cyclopentanone. It is seen in amcinonide (triamcinolone acetate cyclopentanonide). | 0 | Theoretical and Fundamental Chemistry |
In genetics, a mutagen is a physical or chemical agent that permanently changes genetic material, usually DNA, in an organism and thus increases the frequency of mutations above the natural background level. As many mutations can cause cancer in animals, such mutagens can therefore be carcinogens, although not all necessarily are. All mutagens have characteristic mutational signatures with some chemicals becoming mutagenic through cellular processes.
The process of DNA becoming modified is called mutagenesis. Not all mutations are caused by mutagens: so-called "spontaneous mutations" occur due to spontaneous hydrolysis, errors in DNA replication, repair and recombination. | 0 | Theoretical and Fundamental Chemistry |
In organic chemistry, isothiouronium is a functional group with the formula [RSC(NH)] (R = alkyl, aryl) and is the acid salt of isothiourea. The H centres can also be replaced by alkyl and aryl. Structurally, these cations resemble guanidinium cations. The CNS core is planar and the C–N bonds are short. | 0 | Theoretical and Fundamental Chemistry |
Using ostracod crustaceans as palaeoclimate proxies has been well established for the Quaternary. Not only their indicator species, but also the trace element and stable isotope geochemistry of their shells have been documented as evidence of past climate fluctuations. | 0 | Theoretical and Fundamental Chemistry |
Dexmedetomidine may enhance the effects of other sedatives and anesthetics when co-administered. Similarly, drugs that lower blood pressure and heart rate, such as beta blockers, may also have enhanced effects when co-administered with dexmedetomidine. | 0 | Theoretical and Fundamental Chemistry |
Recognition of the field of Transition Engineering and Energy Transition Engineering started in 2010 when the Institution of Engineering and Technology (IET) Prestige Lecture in NZ was given by Associate Professor Susan Krumdieck, University of Canterbury.
In 2014 the engineering text book, "Principles of Sustainable Energy Systems" by Professor Frank Kreith, featured Chapter 13 on Transition Engineering.
In 2017, Transition Engineering was invited for Chapter 32 the book "Energy Solutions to Combat Global Warming".
In 2019, a full text on the methodologies and principles of transition engineering was published, "Transition Engineering, Building a Sustainable Future".
Since 2015, Transition Engineering has been taught at the university level in a range of full courses, workshops, guest lectures and seminars. Courses have been held in Grenoble INP, France; Munich University of Applied Sciences, Germany; University of Duisburg-Essen, Germany; Bristol University, UK; at University of Canterbury, New Zealand, and Heriot-Watt University, Scotland. In 2020 the first on-line courses were offered continuing professional development for engineers and other professionals. | 1 | Applied and Interdisciplinary Chemistry |
As of 2016, the U.S. Environmental Protection Agency had conditionally registered, for a period of four years, only two nanomaterial pesticides as ingredients. The EPA differentiates nanoscale ingredients from non-nanoscale forms of the ingredient, but there is little scientific data about potential variation in toxicity. Testing protocols still need to be developed. | 0 | Theoretical and Fundamental Chemistry |
* (German) Richard van Basshuysen: Handbuch Verbrennungsmotor, Fred Schäfer; 3. Auflage; 2005; Vieweg Verlag | 0 | Theoretical and Fundamental Chemistry |
In 2009, Erik Verlinde proposed a conceptual model that describes gravity as an entropic force. He argues (similar to Jacobsons result) that gravity is a consequence of the "information associated with the positions of material bodies". This model combines the thermodynamic approach to gravity with Gerard t Hoofts holographic principle. It implies that gravity is not a fundamental interaction, but an emergent phenomenon which arises from the statistical behavior of microscopic degrees of freedom encoded on a holographic screen. The paper drew a variety of responses from the scientific community. Andrew Strominger, a string theorist at Harvard said "Some people have said it cant be right, others that it's right and we already knew it – that it’s right and profound, right and trivial."
In July 2011, Verlinde presented the further development of his ideas in a contribution to the Strings 2011 conference, including an explanation for the origin of dark matter.
Verlinde's article also attracted a large amount of media exposure, and led to immediate follow-up work in cosmology, the dark energy hypothesis, cosmological acceleration, cosmological inflation, and loop quantum gravity. Also, a specific microscopic model has been proposed that indeed leads to entropic gravity emerging at large scales. Entropic gravity can emerge from quantum entanglement of local Rindler horizons. | 0 | Theoretical and Fundamental Chemistry |
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