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In 1986, Novotny was given the Award in Chromatography from the American Chemical Society. Novotny received the ANACHEM award in 1992. This award is given to outstanding analytical chemists for teaching, research, administration or other activities which have advanced of the field.
Novotny was also selected as the LCGC Lifetime Achievement award recipient in 2019. | 0 | Theoretical and Fundamental Chemistry |
Arenediazonium salts have been reported as an alternative to aryl halides for the Sonogashira coupling reaction. Gold(I) chloride has been used as co-catalyst combined with palladium(II) chloride in the coupling of arenediazonium salts with terminal alkynes, a process carried out in the presence of bis-2,6-diisopropylphenyl dihydroimidazolium chloride (IPr NHC) (5 mol%) to in situ generate a NHC–palladium complex, and 2,6-di-tert-butyl-4-methylpyridine (DBMP) as base in acetonitrile as solvent at room temperature. This coupling can be carried out starting from anilines by formation of the diazonium salt followed by in situ
Sonogashira coupling, where anilines are transformed into diazonium salt and furtherly converted into alkyne by coupling with phenylacetylene. | 0 | Theoretical and Fundamental Chemistry |
Algae biodiesel is still a fairly new technology. Despite the fact that research began over 30 years ago, it was put on hold during the mid-1990s, mainly due to a lack of funding and a relatively low petroleum cost. For the next few years algae biofuels saw little attention; it was not until the gas peak of the early 2000s that it eventually had a revitalization in the search for alternative fuel sources.
Increasing interest in seaweed farming for carbon sequestration, eutrophication reduction and production of food has resulted in the creation of commercial seaweed cultivation since 2017. Reductions in the cost of cultivation and harvesting as well as the development of commercial industry will improve the economics of macroalgae biofuels. Climate change has created a proliferation of brown macroalgae mats, which wash up on the shores of the Caribbean. Currently these mats are disposed of but there is interest in developing them into a feedstock for biofuel production. | 1 | Applied and Interdisciplinary Chemistry |
Many nickel-based superalloys depend on solid solution as a strengthening mechanism. The most popular example is the Inconel family, where many of these alloys contain chromium and iron and some other additions of cobalt, molybdenum, niobium, and titanium. The nickel-based superalloys are well known for their intensive use in the industrial field especially the aeronautical and the aerospace industry due to their superior mechanical and corrosion properties at high temperatures. | 1 | Applied and Interdisciplinary Chemistry |
* The Tarot, Magic, Alchemy, Hermeticism, and Neoplatonism, Second Edition 2019,
*Alchemy and the Tarot: An Examination of the Historic Connection between Alchemy and the Tarot, with a Guide to The Alchemical Tarot, 2011,
* The Fools Journey: the History, Art, & Symbolism of the Tarot', 2010,
* Mysteries, Legends, and Unexplained Phenomena Series: Magic and Alchemy, 2009,
* The Vampire Tarot, 2009,
* Mysteries, Legends, and Unexplained Phenomena Series: Shamanism, 2008,
* Mysteries, Legends, and Unexplained Phenomena Series: Astrology and Divination, 2008,
* The Tarot: History, Symbolism, and Divination, 2005,
* The Buddha Tarot Companion: A Mandala of Cards, 2004,
* A Gnostic Book of Saints, 2001,
* The Angels Tarot, coauthored with Rosemary Ellen Guiley, 1995,
* The Alchemical Tarot, coauthored with Rosemary Ellen Guiley, 1995, | 1 | Applied and Interdisciplinary Chemistry |
In swimming or flying animals, Strouhal number is defined as
where,
: f = oscillation frequency (tail-beat, wing-flapping, etc.),
: U = flow rate,
: A = peak-to-peak oscillation amplitude.
In animal flight or swimming, propulsive efficiency is high over a narrow range of Strouhal constants, generally peaking in the 0.2 < St < 0.4 range. This range is used in the swimming of dolphins, sharks, and bony fish, and in the cruising flight of birds, bats and insects. However, in other forms of flight other values are found. Intuitively the ratio measures the steepness of the strokes, viewed from the side (e.g., assuming movement through a stationary fluid) – f is the stroke frequency, A is the amplitude, so the numerator fA is half the vertical speed of the wing tip, while the denominator V is the horizontal speed. Thus the graph of the wing tip forms an approximate sinusoid with aspect (maximal slope) twice the Strouhal constant. | 1 | Applied and Interdisciplinary Chemistry |
These catalysts are metallocenes together with a cocatalyst, typically MAO, −[O−Al(CH)]−. The idealized metallocene catalysts have the composition CpMCl (M = Ti, Zr, Hf) such as titanocene dichloride. Typically, the organic ligands are derivatives of cyclopentadienyl. In some complexes, the two cyclopentadiene (Cp) rings are linked with bridges, like −CH−CH− or >SiPh. Depending on the type of their cyclopentadienyl ligands, for example by using an ansa-bridge, metallocene catalysts can produce either isotactic or syndiotactic polymers of propylene and other 1-alkenes. | 0 | Theoretical and Fundamental Chemistry |
A number of distinct reactions are associated with the term ATP-dependent chromatin remodeling. Remodeling enzymes have been shown to slide nucleosomes along DNA, disrupt histone-DNA contacts to the extent of destabilizing the H2A/H2B dimer and to generate negative superhelical torsion in DNA and chromatin. Recently, the Swr1 remodeling enzyme has been shown to introduce the variant histone H2A.Z into nucleosomes. At present, it is not clear if all of these represent distinct reactions or merely alternative outcomes of a common mechanism. What is shared between all, and indeed the hallmark of ATP-dependent chromatin remodeling, is that they all result in altered DNA accessibility.
Studies looking at gene activation in vivo and, more astonishingly, remodeling in vitro have revealed that chromatin remodeling events and transcription-factor binding are cyclical and periodic in nature. While the consequences of this for the reaction mechanism of chromatin remodeling are not known, the dynamic nature of the system may allow it to respond faster to external stimuli. A recent study indicates that nucleosome positions change significantly during mouse embryonic stem cell development, and these changes are related to binding of developmental transcription factors. | 1 | Applied and Interdisciplinary Chemistry |
In molecular biology and physiology, something is GABAergic or GABAnergic if it pertains to or affects the neurotransmitter gamma-aminobutyric acid (GABA). For example, a synapse is GABAergic if it uses GABA as its neurotransmitter, and a GABAergic neuron produces GABA. A substance is GABAergic if it produces its effects via interactions with the GABA system, such as by stimulating or blocking neurotransmission.
A GABAergic or GABAnergic agent is any chemical that modifies the effects of GABA in the body or brain. Some different classes of GABAergic drugs include agonists, antagonists, modulators, reuptake inhibitors and enzymes. | 1 | Applied and Interdisciplinary Chemistry |
Dr. Norbert Bischofberger (born 10 January 1956 in Mellau, Austria) is an Austrian scientist and one of the inventors of the antiviral drug Tamiflu generically known as oseltamivir, which is, as of 2009, the only oral medication on the market to treat influenza A and B as well as the 2009 Pandemic H1N1 (swine flu), the spread of which caused an ongoing pandemic in 2009. Bischofberger is currently the President & Chief Executive Officer of Kronos Bio, and previously was the Executive Vice President, Research and Development and Chief Scientific Officer at Gilead Sciences, a biopharmaceutical company specializing in antivirals. | 0 | Theoretical and Fundamental Chemistry |
* Bacteroides spp., including B. fragilis
* Enterobacter spp.
* Escherichia coli
* Haemophilus influenzae
* Klebsiella species
* Morganella morganii
* Neisseria gonorrhoeae
* Proteus mirabilis
* Proteus vulgaris
* Providencia rettgeri
* Pseudomonas spp., including P. aeruginosa
* Serratia marcescens | 0 | Theoretical and Fundamental Chemistry |
The ascidian mitochondrial code (translation table 13) is a genetic code found in the mitochondria of Ascidia. | 1 | Applied and Interdisciplinary Chemistry |
The 4-1BB/4-1BBL complex consists of three monomeric 4-1BBs bound to a trimeric 4-1BBL. Each 4-1BB monomer binds to two 4-1BBLs via cysteine-rich domains (CRDs). The interaction between 4-1BB and the second 4-1BBL is required to stabilize their interactions. The link with 4-1BBL is largely made up of amino acids from the dynamic loops of the CRD2 and the β sheet of CRD3 of 4-1BB, according to a detailed study of the binding between the 4-1BB and 4-1BBL interface. CRD2 amino acids (T61, Q67, and K69) interact with the AA′ loop (Y110 and G114) and the intra-H-strand loop (Q227 and Q230) of 4-1BBL to form various hydrogen bond interactions. | 1 | Applied and Interdisciplinary Chemistry |
A nanodomain is a nanometer-sized cluster of proteins found in a cell membrane. They are associated with the signal which occurs when a single calcium ion channel opens on a cell membrane, allowing an influx of calcium ions (Ca) which extend in a plume a few tens of nanometres from the channel pore. In a nanodomain, the coupling distance, that is, the distance between the calcium-binding proteins which sense the calcium, and the calcium channel, is very small, less than , which allows rapid signalling. The formation of a nanodomain signal is virtually instantaneous following the opening of the calcium channel, as calcium ions move rapidly into the cell along a steep concentration gradient. The nanodomain signal collapses just as quickly when the calcium channel closes, as the ions rapidly diffuse away from the pore. Formation of a nanodomain signal requires the influx of only approximately 1000 calcium ions.
Coupling distances greater than , mediated by a larger number of channels, are referred to as microdomains. nanodomain | 1 | Applied and Interdisciplinary Chemistry |
The Stillson wrench is an adjustable wrench (spanner) with hardened serrated teeth on its jaws. The hard teeth bite into the softer metal of the round pipe and provide the grip needed to turn a pipe, even against fair resistance. The design of the adjustable jaw, which permits a certain amount of intentional play out of square, allows it to bind on the pipe, with forward pressure on the handle pulling the jaws tighter. On some models, two leaf springs, above and below the knurled adjusting knob, help unlock the jaw when pressure on the handle of the wrench is released.
Pipe wrenches are not intended for regular use on hex nuts or other fittings. However, if a hex nut becomes rounded (stripped) so that it cannot be moved by standard wrenches, a pipe wrench can be used to free the bolt or nut, because the pipe wrench is designed to bite into rounded metal surfaces.
Pipe wrenches are classified by the length of the handle. They are generally available in sizes from to or larger. They are usually made of forged steel. Today, aluminium might be substituted to reduce the weight of the body of the wrench, although the teeth and jaw remain steel. Teeth and jaw kits (which also contain adjustment rings and springs) can be bought to repair broken wrenches. | 1 | Applied and Interdisciplinary Chemistry |
This includes screws, as well as bolts. This is often used as it requires relatively little specialist equipment, and are therefore often used in flat-pack furniture. It can also be used when a metal is joined to another material (such as wood) or a particular metal does not weld well (such as aluminum). This can be done to directly join metals, or with an intermediate material such as nylon. While often weaker than other methods such as welding or brazing, the metal can easily be removed and therefore reused or recycled. It can also be done in conjunction with an epoxy or glue, reverting its ecological benefits. | 1 | Applied and Interdisciplinary Chemistry |
Carolinium and berzelium were the proposed names for new chemical elements that Charles Baskerville believed he had isolated from the already known element thorium.
During his time at the University of North Carolina, Baskerville experimented with thorium and published his results in 1901. He reported having separated thorium into three fractions with slightly different chemical properties: the known thorium and two new elements, carolinium (symbol Cn) and berzelium (symbol Bz).
The names derived from two sources:
# the first element was named for the State in which the university was located at which the experiments were done, North Carolina, and
# the other element was named after Jöns Jakob Berzelius, a renowned Swedish chemist and discoverer of silicon, selenium, cerium and thorium.
As a response to the publication Bohuslav Brauner claimed that he already stated the fact that thorium should be a mixture of several elements.
In 1905, R. J. Meyer and A. Gumperz failed to replicate the results, and showed that thorium is only one element and not a mixture.
H. G. Wellss 1914 novel The World Set Free' features an atomic bomb based on the similarly named "Carolinum". When detonated, the bomb continues to explode indefinitely. | 1 | Applied and Interdisciplinary Chemistry |
The sum of the mass concentrations of all components (including the solvent) gives the density of the solution:
Thus, for pure component the mass concentration equals the density of the pure component. | 0 | Theoretical and Fundamental Chemistry |
The IGSN was developed as part of SESAR with the support of the National Science Foundation at the Lamont–Doherty Earth Observatory. The project was initiated and managed by the Geoinformatics for Geochemistry Program under the direction of Kerstin Lehnert to address data curation obstacles such as different samples that share the same name, and samples that are renamed as they move between laboratories and thus generating analyses that are published under different aliases. As a result, metadata that ensure unique identification are often missing and this causes irritation for future reuse of data from a sample or the sample itself. Sample databases, such as the SESAR database, are designed to address these issues.
At a workshop hosted at the San Diego Supercomputer Center in 2011, a group of experts met to discuss how to transition the IGSN project into a sustainable infrastructure. The group recommended opening the system to other IGSN registration agents, making it international and transferring the operation and governance of the IGSN to an independent body. This recommendation led to the foundation of the International Geo Sample Implementation Organization e.V. (IGSN e.V.) and the founding event was held at the American Geophysical Union Fall Meeting 2011 in San Francisco, California. The IGSN e.V. is an incorporated organisation under German law and is registered at the Magistrates Court in Potsdam, Germany.
Membership in the organisation is open only to institutions, not to individuals. At present, IGSN e.V. has 16 full members.
In 2018, the Alfred P. Sloan Foundation awarded Columbia University's Lamont–Doherty Earth Observatory a grant for a project to modernise the IGSN business model and system architecture. The funding from the Sloan Foundation will support a series of workshops, at which international experts will come together to redesign the IGSN system and its management to allow researchers world-wide use the IGSN with confidence.
In September 2021, IGSN e.V. and DataCite entered a partnership under which DataCite will provide the IGSN ID registration services and supporting technology to enable the ongoing sustainability of the IGSN PID infrastructure. The IGSN e.V. will facilitate a Community of Communities to promote and support new research and innovation for standard methods of identifying, citing, and locating physical samples. The partnership allows IGSN to leverage DataCite DOI registration services and to focus community efforts on advocacy and expanding the global samples ecosystem.
IGSN and DataCite have a common purpose, and a close relationship in the future will provide mutual benefit to our shared vision of connecting research and identifying knowledge. The partnership brings years of experience across our organizations and communities to scale sample community engagement, develop sample identifier practice standards, and increase adoption globally. In a study published 2023 by [https://www.knowledge-exchange.info/ Knowledge Exchange] it is highlighted that IGSN IDs point to physical objects instead of intellectual property or outcomes (as DOIs mostly do) or their creators. Besides, the report emphasized that the service itself and its organisational framework were developed bottom-up in a sheer community-based effort. | 0 | Theoretical and Fundamental Chemistry |
Due to their ability to scatter light back into the photovoltaic structure and low absorption, plasmonic nanoparticles are under investigation as a method for increasing solar cell efficiency. Forcing more light to be absorbed by the dielectric increases efficiency.
Plasmons can be excited by optical radiation and induce an electric current from hot electrons in materials fabricated from gold particles and light-sensitive molecules of porphin, of precise sizes and specific patterns. The wavelength to which the plasmon responds is a function of the size and spacing of the particles. The material is fabricated using ferroelectric nanolithography. Compared to conventional photoexcitation, the material produced three to 10 times the current. | 0 | Theoretical and Fundamental Chemistry |
Cytidine residues, modified once to m5C (discussed above), can be further modified: either oxidised once for 5-hydroxylmethylcytidine (hm5C), or oxidised twice for 5-formylcytidine (f5C). Arising from the oxidative processing of m5C enacted in mammals by ten-eleven translocation (TET) family enzymes, hm5C is known to occur in all three kingdoms and to have roles in regulation. While 5-hydroxymethylcytidine (hm5dC) is known to be found in DNA in a widespread manner, hm5C is also found in organisms for which no hm5dC has been detected, indicating it is a separate process with distinct regulatory stipulations. To observe the in vivo addition of methyl groups to cytosine RNA residues followed by oxidative processing, mice can be fed on a diet incorporating particular isotopes and these be traced by LC-MS/MS analysis. Since the metabolic pathway from nutritional intake to nucleotide incorporation is known to progress from dietary methionine --> S-adenosylmethionine (SAM) --> methyl group on RNA base, the labelling of dietary methionine with C and D means these will end up in hm5C residues that have been altered since the addition of these into the diet. In contrast to m5C, a large quantity of hm5C modifications have been recorded within coding sequences. | 1 | Applied and Interdisciplinary Chemistry |
The anabaseine molecule consists of a non-aromatic tetrahydropyridine ring connected to the 3rd carbon of a 3-pyridyl ring. It can exist in three forms at physiological pH: a ketone, imine, or iminium structure. Due to conjugation between the imine and 3-pyridyl ring, anabaseine exists as a nearly coplanar molecule. | 1 | Applied and Interdisciplinary Chemistry |
Biosurfactants enhance the emulsification of hydrocarbons, thus they have the potential to solubilise hydrocarbon contaminants and increase their availability for microbial degradation. In addition, biosurfactants can modify the cell surface of bacteria that biodegrade hydrocarbons, which can also increase the biodegradability of these pollutants to cells. These compounds can also be used in enhanced oil recovery and may be considered for other potential applications in environmental protection. | 0 | Theoretical and Fundamental Chemistry |
Plastid terminal oxidase or plastoquinol terminal oxidase (PTOX) is an enzyme that resides on the thylakoid membranes of plant and algae chloroplasts and on the membranes of cyanobacteria. The enzyme was hypothesized to exist as a photosynthetic oxidase in 1982 and was verified by sequence similarity to the mitochondrial alternative oxidase (AOX). The two oxidases evolved from a common ancestral protein in prokaryotes, and they are so functionally and structurally similar that a thylakoid-localized AOX can restore the function of a PTOX knockout. | 0 | Theoretical and Fundamental Chemistry |
Research based on the split gene theory sheds light on other basic questions of exons and introns. The exons of eukaryotes are generally short (human exons average ~120 bases, and can be as short as 10 bases) and introns are usually long (average of ~3,000 bases, and can be several hundred thousands bases long), for example genes RBFOX1, CNTNAP2, PTPRD and DLG2. Senapathy provided a plausible answer to these questions, the only explanation to date. If eukaryotic genes originated from random DNA sequences, they have to match the lengths of ORFs from random sequences, and possibly should be around 100 bases (close to the median length of ORFs in random sequence). The genome sequences of living organisms exhibit exactly the same average lengths of 120 bases for exons, and the longest exons of 600 bases (with few exceptions), which is the same length as that of the longest random ORFs.
If split genes originated in random DNA sequences, then introns would be long for several reasons. The stop codons occur in clusters leading to numerous consecutive short ORFs: longer ORFs that could be defined as exons would be rarer. Furthermore, the best of the coding sequence parameters for functional proteins would be chosen from the long ORFs in random sequence, which may occur rarely. In addition, the combination of donor and acceptor splice junction sequences within short lengths of coding sequence segments that would define exon boundaries would occur rarely in a random sequence. These combined reasons would make introns long compared to exons. | 1 | Applied and Interdisciplinary Chemistry |
Mach reflection can exist in steady, pseudo-steady and unsteady flows. When a shock wave, which is moving with a constant velocity, propagates over a solid wedge, the flow generated by the shock impinges
on the wedge thus generating a second reflected shock, which ensures that the velocity of
the flow is parallel to the wedge surface. Viewed in the frame of the reflection point, this
flow is locally steady, and the flow is referred to as pseudosteady. When
the angle between the wedge and the primary shock is sufficiently large, a single reflected
shock is not able to turn the flow to a direction parallel to the wall and a transition to Mach
reflection occurs.
In a steady flow situation, if a wedge is placed into a steady supersonic flow in such
a way that its oblique attached shock impinges on a flat wall parallel to the free stream,
the shock turns the flow toward the wall and a reflected shock is required to turn the flow
back to a direction parallel to the wall. When the shock angle exceeds a certain value, the
deflection achievable by a single reflected shock is insufficient to turn the flow back to a
direction parallel to the wall and transition to Mach reflection is observed.
Mach reflection consists of three shocks, namely the incident shock, the reflected shock and a Mach stem, as well as a slip plane. The point where the three shocks meet is known as the triple point in two dimensions, or a shock-shock in three dimensions. | 1 | Applied and Interdisciplinary Chemistry |
Cyanophages are viruses that infect cyanobacteria. Cyanophages can be found in both freshwater and marine environments. Marine and freshwater cyanophages have icosahedral heads, which contain double-stranded DNA, attached to a tail by connector proteins. The size of the head and tail vary among species of cyanophages.
Cyanophages, like other bacteriophages, rely on Brownian motion to collide with bacteria, and then use receptor binding proteins to recognize cell surface proteins, which leads to adherence. Viruses with contractile tails then rely on receptors found on their tails to recognize highly conserved proteins on the surface of the host cell.
Cyanophages infect a wide range of cyanobacteria and are key regulators of the cyanobacterial populations in aquatic environments, and may aid in the prevention of cyanobacterial blooms in freshwater and marine ecosystems. These blooms can pose a danger to humans and other animals, particularly in eutrophic freshwater lakes. Infection by these viruses is highly prevalent in cells belonging to Synechococcus spp. in marine environments, where up to 5% of cells belonging to marine cyanobacterial cells have been reported to contain mature phage particles.
The first cyanophage, LPP-1, was discovered in 1963. Cyanophages are classified within the bacteriophage families Myoviridae (e.g. AS-1, N-1), Podoviridae (e.g. LPP-1) and Siphoviridae (e.g. S-1). | 0 | Theoretical and Fundamental Chemistry |
A galvanic cell or voltaic cell, named after the scientists Luigi Galvani and Alessandro Volta, respectively, is an electrochemical cell in which an electric current is generated from spontaneous oxidation–reduction reactions. A common apparatus generally consists of two different metals, each immersed in separate beakers containing their respective metal ions in solution that are connected by a salt bridge or separated by a porous membrane.
Volta was the inventor of the voltaic pile, the first electrical battery. Common usage of the word battery has evolved to include a single Galvanic cell, but the first batteries had many Galvanic cells. | 1 | Applied and Interdisciplinary Chemistry |
Intron-mediated enhancement (IME) is the ability of an intron sequence to enhance the expression of a gene containing that intron. In particular, the intron must be present in the transcribed region of the gene for enhancement to occur, differentiating IME from the action of typical transcriptional enhancers. Descriptions of this phenomenon were first published in cultured maize cells in 1987, and the term "intron-mediated enhancement" was subsequently coined in 1990. A number of publications have demonstrated that this phenomenon is conserved across eukaryotes, including humans, mice, Arabidopsis, rice, and C. elegans. However, the mechanism(s) by which IME works are still not completely understood.
When testing to see whether any given intron enhances the expression of a gene, it is typical to compare the expression of two constructs, one containing the intron and one without it, and to express the difference between the two results as a "fold increase" in enhancement. Further experiments can specifically point to IME as the cause of expression enhancement - one of the most common is to move the intron upstream of the transcription start site, removing it from the transcript. If the intron can no longer enhance expression, then inclusion of the intron in the transcript is important, and the intron probably causes IME.
Not all introns enhance gene expression, but those that do can enhance expression between 2– and >1,000–fold relative to an intronless control. In Arabidopsis and other plant species, the [http://korflab.ucdavis.edu/cgi-bin/IMEter_2014/web-imeter2.1.pl IMEter] has been developed to calculate the likelihood that an intron sequence will enhance gene expression. It does this by calculating a score based on the patterns of nucleotide sequences within the target sequence. The position of an intron within the transcript is also important - the closer an intron is to the start (5' end) of a transcript, the greater its enhancement of gene expression. | 1 | Applied and Interdisciplinary Chemistry |
Amidrazones are a class of chemical compounds formally derived from carboxylic acids. Amidrazones can exists in two tautomeric forms: hydrazide imides (RC(=NH)NHNH) and amide hydrazones (RC(NH)=NNH). | 0 | Theoretical and Fundamental Chemistry |
1,4-alpha-glucan-branching enzyme, also known as brancher enzyme or glycogen-branching enzyme is an enzyme that in humans is encoded by the GBE1 gene.
Glycogen branching enzyme is an enzyme that adds branches to the growing glycogen molecule during the synthesis of glycogen, a storage form of glucose. More specifically, during glycogen synthesis, a glucose 1-phosphate molecule reacts with uridine triphosphate (UTP) to become UDP-glucose, an activated form of glucose. The activated glucosyl unit of UDP-glucose is then transferred to the hydroxyl group at the C-4 of a terminal residue of glycogen to form an α-1,4-glycosidic linkage, a reaction catalyzed by glycogen synthase. Importantly, glycogen synthase can only catalyze the synthesis of α-1,4-glycosidic linkages. Since glycogen is a readily mobilized storage form of glucose, the extended glycogen polymer is branched by glycogen branching enzyme to provide glycogen breakdown enzymes, such as glycogen phosphorylase, with many terminal residues for rapid degradation. Branching also importantly increases the solubility and decreases the osmotic strength of glycogen.
The protein encoded by this gene is a glycogen branching enzyme that catalyzes the transfer of alpha-1,4-linked glucosyl units from the outer end of a glycogen chain to an alpha-1,6 position on the same or a neighboring glycogen chain. Branching of the chains is essential to increase the solubility of the glycogen molecule and, consequently, in reducing the osmotic pressure within cells. The highest levels of this enzyme are found in liver and muscle cells. Mutations in this gene are associated with glycogen storage disease type IV (also known as Andersen's disease). | 1 | Applied and Interdisciplinary Chemistry |
Winifred Burks-Houck (August 20, 1950 – May 6, 2004) was an environmental organic chemist and the first female president of National Organization for the Professional Advancement of Black Chemists and Chemical Engineers (NOBCChE), serving from 1993 – 2001. | 0 | Theoretical and Fundamental Chemistry |
The viperwolf (Nantang in Navi) is a hexapodal nocturnal carnivore. The species is scientifically known as Caniferratus costatus. It has bioluminescence for pack identification. Cameron described the viperwolves: "[They are] hairless with shiny skin that looks like overlapped armor. Most disturbing are its paws, which are like leathery hands." They are vicious in combat but treat their babies in a loving, nurturing way. Their first appearance is when Jake is lost at night and he is attacked by an angry pack of viper wolves, after which he is rescued by Neytiri. They are seen in the daytime caring for their babies and have green eyes. They have a laugh which sounds like Earths hyenas. Like most Pandoran creatures, they have antennae. They have opposable thumbs allowing them to climb trees as well as stalk from the ground, thereby are able to create a three-dimensional hunting field. | 1 | Applied and Interdisciplinary Chemistry |
Common high-activity activators are mineral acids, often together with halides, amines, water or alcohols:
* hydrochloric acid, most common
* phosphoric acid, less common, use limited by its polymerization at higher temperatures
Inorganic acids are highly corrosive to metals even at room temperature, which causes issues during storage, handling and applications. As soldering involves high temperatures, compounds that decompose or react, with acids as products, are frequently used:
* zinc chloride, which at high temperatures reacts with moisture, forming oxychloride and hydrochloric acid
* ammonium chloride, thermally decomposing to ammonia and hydrochloric acid
* amine hydrochlorides, decomposing to the amine and hydrochloric acid | 1 | Applied and Interdisciplinary Chemistry |
2,3-butanediol has a variety of industrial applications and products it can produce. The levo isomer of butanediol has a low freezing point of -60 °C, which allows it to work as an antifreeze agent. Through catalytic dehydrogenation, butanediol can form diacetyl. Diacetyl is a food additive that can be used to add flavor. 0.1% butanediol will kill most pathogenic bacteria due to its antiseptic properties. Through esterification, forms of precursors of polyurethane foams are produced. These can be used in various applications, including in pharmaceuticals, cosmetics, lotions, ointments, and antiperspirants. Butanediol itself even has applications in the pharmaceutical industry as a drug carrier. | 1 | Applied and Interdisciplinary Chemistry |
Another route to isocyanides entails deprotonation of oxazoles and benzoxazoles in the 2-position. The resulting organolithium compound exists in chemical equilibrium with the 2-isocyanophenolate, which can be captured by an electrophile such as an acid chloride. | 0 | Theoretical and Fundamental Chemistry |
The original incarnation of FutureGen was as a public-private partnership to build the world's first near zero-emissions coal-fueled power plant. The 275-megawatt plant would be intended to prove the feasibility of producing electricity and hydrogen from coal while capturing and permanently storing carbon dioxide underground. The Alliance intended to build the plant in Mattoon Township, Coles County, Illinois northwest of Mattoon, Illinois, subject to necessary approvals (issuing a “Record of Decision”) by the Department of Energy (DOE) as part of the National Environmental Policy Act (NEPA) process.
FutureGen was to be designed, developed and operated by the FutureGen Industrial Alliance, a non-profit consortium of coal mining and electric utility companies formed to partner with the DOE on the FutureGen project. The project was still in the development stage when its funding was cancelled in January 2008. The Alliance decision of the location of the host site, subject to DOE's completing NEPA environmental reviews, was announced in December 2007 after a two-year bidding and review process. Construction was scheduled to begin in 2009, with full-scale plant operations to begin in 2012.
The estimated gross project cost, including construction and operations, and excluding offsetting revenue, was $1.65 billion. The project was governed by a legally binding cooperative agreement between DOE and the Alliance. Under the agreement, DOE was to provide 74% of the project’s cost, with private industry contributing the other 26%. The DOE also planned to solicit the financial support and participation of international governments in the FutureGen project, since by 2020 more than 60% of man-made greenhouse gas emissions are expected to come from developing countries. Foreign financial support was to offset a portion of DOE’s cost-share. As of January 2008, the foreign governments of China, India, Australia, South Korea, and Japan had expressed interest in participating and sharing the cost of the project.
FutureGen was to sequester carbon dioxide emissions at a rate of one million metric tons per year for four years, which is the scale a Massachusetts Institute of Technology (MIT) report cites as appropriate for proving sequestration. The MIT report also states that “the priority objective with respect to coal should be the successful large-scale demonstration of the technical, economic, and environmental performance of the technologies that make up all of the major components of a large-scale integrated CCS system — capture, transportation and storage.” An injection field test similar to this was done in Norway.
In March 2009 Washington Post reported that U.S. Secretary of Energy Steven Chu expressed support for continuing the project using stimulus funds (after some changes that have not yet been specified) and making it a part of a larger portfolio of research plants developed in collaboration with other countries.
Following the successful completion of the first phase, in February 2013, the Energy Department announced the beginning of Phase II of the project development with a new cooperative agreement between the FutureGen Industrial Alliance and the Department of Energy. This means that the FutureGen project has government support as it moves into its third phase, deployment of the project. | 1 | Applied and Interdisciplinary Chemistry |
When coal is burned, various chemicals are released into the air. These chemicals include mercury, lead and other heavy metals, sulfur dioxide, and nitrogen oxides, the primary molecules contributing to the formation of acid rain. Additionally, an abundance of (CO), the primary greenhouse gas associated with burning fossil fuels, enters the atmosphere, contributing to smog. Finally, the burning of coal can lead to the release of small amounts of radioactive materials occurring naturally within anthracite.
Coal pollution mitigation is a series of systems and technologies that seek to mitigate the Health and environmental impact of the coal industry|health and environmental impact of coal; in particular, air pollution from coal-fired power stations and from coal burnt by heavy industry. Systems of coal pollution mitigation primarily focus on mitigating the release of sulfur dioxide, nitrogen oxides, and particulates comprising chemical smog, which cause visible air pollution, illness, and premature deaths.
Sulfur dioxide can be removed by flue-gas desulfurization and nitrogen oxides by selective catalytic reduction (SCR). Particulates can be removed with electrostatic precipitators. Although perhaps less efficient, wet scrubbers can remove both gasses and particulates. Reducing fly ash reduces emissions of naturally occurring radioactive materials. Mercury emissions can be reduced by up to 95%. Capturing carbon dioxide emissions from coal is a process in which a relatively pure stream of carbon dioxide from industrial sources is separated, treated, and transported to a long-term storage location. | 1 | Applied and Interdisciplinary Chemistry |
Philippe Gengembre (1764–1838), a student of Lavoisier, first obtained phosphine in 1783 by heating white phosphorus in an aqueous solution of potash (potassium carbonate).
Perhaps because of its strong association with elemental phosphorus, phosphine was once regarded as a gaseous form of the element, but Lavoisier (1789) recognised it as a combination of phosphorus with hydrogen and described it as phosphure dhydrogène' (phosphide of hydrogen).
In 1844, Paul Thénard, son of the French chemist Louis Jacques Thénard, used a cold trap to separate diphosphine from phosphine that had been generated from calcium phosphide, thereby demonstrating that is responsible for spontaneous flammability associated with , and also for the characteristic orange/brown color that can form on surfaces, which is a polymerisation product. He considered diphosphine's formula to be , and thus an intermediate between elemental phosphorus, the higher polymers, and phosphine. Calcium phosphide (nominally ) produces more than other phosphides because of the preponderance of P-P bonds in the starting material.
The name "phosphine" was first used for organophosphorus compounds in 1857, being analogous to organic amines (). The gas was named "phosphine" by 1865 (or earlier). | 0 | Theoretical and Fundamental Chemistry |
Pentaoxidane is an inorganic compound of hydrogen and oxygen with the chemical formula . This is one of the most unstable hydrogen polyoxides. | 0 | Theoretical and Fundamental Chemistry |
Suction cavitation occurs when the pump suction is under a low-pressure/high-vacuum condition where the liquid turns into a vapor at the eye of the pump impeller. This vapor is carried over to the discharge side of the pump, where it no longer sees vacuum and is compressed back into a liquid by the discharge pressure. This imploding action occurs violently and attacks the face of the impeller. An impeller that has been operating under a suction cavitation condition can have large chunks of material removed from its face or very small bits of material removed, causing the impeller to look spongelike. Both cases will cause premature failure of the pump, often due to bearing failure. Suction cavitation is often identified by a sound like gravel or marbles in the pump casing.
Common causes of suction cavitation can include clogged filters, pipe blockage on the suction side, poor piping design, pump running too far right on the pump curve, or conditions not meeting NPSH (net positive suction head) requirements.
In automotive applications, a clogged filter in a hydraulic system (power steering, power brakes) can cause suction cavitation making a noise that rises and falls in synch with engine RPM. It is fairly often a high pitched whine, like set of nylon gears not quite meshing correctly. | 1 | Applied and Interdisciplinary Chemistry |
Biolistics introduces DNA randomly into the target cells. Thus the DNA may be transformed into whatever genomes are present in the cell, be they nuclear, mitochondrial, plasmid or any others, in any combination, though proper construct design may mitigate this. The delivery and integration of multiple templates of the DNA construct is a distinct possibility, resulting in potential variable expression levels and copy numbers of the inserted gene. This is due to the ability of the constructs to give and take genetic material from other constructs, causing some to carry no transgene and others to carry multiple copies; the number of copies inserted depends on both how many copies of the transgene an inserted construct has, and how many were inserted. Also, because eukaryotic constructs rely on illegitimate recombination—a process by which the transgene is integrated into the genome without similar genetic sequences—and not homologous recombination, they cannot be targeted to specific locations within the genome, unless the transgene is co-delivered with genome editing reagents. | 1 | Applied and Interdisciplinary Chemistry |
The majority of drugs either
There are 7 main drug actions:
*stimulating action through direct receptor agonism and downstream effects
*depressing action through direct receptor agonism and downstream effects (ex.: inverse agonist)
*blocking/antagonizing action (as with silent antagonists), the drug binds the receptor but does not activate it
*stabilizing action, the drug seems to act neither as a stimulant or as a depressant (ex.: some drugs possess receptor activity that allows them to stabilize general receptor activation, like buprenorphine in opioid dependent individuals or aripiprazole in schizophrenia, all depending on the dose and the recipient)
*exchanging/replacing substances or accumulating them to form a reserve (ex.: glycogen storage)
*direct beneficial chemical reaction as in free radical scavenging
*direct harmful chemical reaction which might result in damage or destruction of the cells, through induced toxic or lethal damage (cytotoxicity or irritation) | 1 | Applied and Interdisciplinary Chemistry |
Natural phenols show optical properties characteristic of benzene, e.g. absorption near 270 nm. According to Woodward's rules, bathochromic shifts often also happen suggesting the presence of delocalised π electrons arising from a conjugation between the benzene and vinyls groups.
As molecules with higher conjugation levels undergo this bathochromic shift phenomenon, a part of the visible spectrum is absorbed. The wavelengths left in the process (generally in red section of the spectrum) recompose the color of the particular substance. Acylation with cinnamic acids of anthocyanidins shifted color tonality (CIE Lab hue angle) to purple.
Here is a series of UV visible spectra of molecules classified from left to right according to their conjugation level:
The absorbance pattern responsible for the red color of anthocyanins may be complementary to that of green chlorophyll in photosynthetically active tissues such as young Quercus coccifera leaves. | 0 | Theoretical and Fundamental Chemistry |
In silico experiments with Monte Carlo simulations demonstrated that both SPINA-GT and SPINA-GD can be estimated with sufficient reliability, even if laboratory assays have limited accuracy. This was confirmed by longitudinal in vivo studies that showed that GT has lower intraindividual variation (i.e. higher reliability) than TSH, FT4 or FT3. | 1 | Applied and Interdisciplinary Chemistry |
An algae scrubber is a water filtering device (not to be confused with a scrubber pad used to clean glass) which uses light to grow algae; in this process, undesirable chemicals are removed from the water. Algae scrubbers allow saltwater, freshwater and pond hobbyists to operate their tanks using natural filtration in the form of primary production, much like oceans and lakes. | 0 | Theoretical and Fundamental Chemistry |
When the speed of sound is known, the Mach number at which an aircraft is flying can be calculated by
where:
: M is the Mach number
: u is velocity of the moving aircraft and
: c is the speed of sound at the given altitude (more properly temperature)
and the speed of sound varies with the thermodynamic temperature as:
where:
: is the ratio of specific heat of a gas at a constant pressure to heat at a constant volume (1.4 for air)
: is the specific gas constant for air.
: is the static air temperature.
If the speed of sound is not known, Mach number may be determined by measuring the various air pressures (static and dynamic) and using the following formula that is derived from Bernoulli's equation for Mach numbers less than 1.0. Assuming air to be an ideal gas, the formula to compute Mach number in a subsonic compressible flow is:
where:
: q is impact pressure (dynamic pressure) and
: p is static pressure
: is the ratio of specific heat of a gas at a constant pressure to heat at a constant volume (1.4 for air)
The formula to compute Mach number in a supersonic compressible flow is derived from the Rayleigh supersonic pitot equation: | 1 | Applied and Interdisciplinary Chemistry |
acid is a member of the carboxylic acid family of organic compounds. It is a structural analog of butyric acid with a hydroxyl functional group and a methyl substituent located on its beta carbon. By extension, other structural analogs include acid and acid. | 1 | Applied and Interdisciplinary Chemistry |
Delapril (INN, also known as alindapril) is an ACE inhibitor used as an antihypertensive drug in some European and Asian countries but not in America. It is taken orally, available in 15 mg and 30 mg tablets. | 0 | Theoretical and Fundamental Chemistry |
Solid materials typically come in two main types: crystalline and amorphous. In either case, a lattice or network of atoms and molecules form. In crystals, the lattice is a very neat, uniform assembly. However, nearly all crystals have defects in the stacking sequence of these molecules and atoms. A vacancy defect, where an atom is simply missing from its place, leaving an empty "hole", is one type of defect. Sometimes atoms can move from place to place within the lattice, creating Schottky defects or Frenkel defects. Other defects can occur from impurities in the lattice. For example, when a normal atom is substituted by a different atom of much larger or smaller size, a substitutional defect occurs, while an interstitial defect occurs when a much smaller atom gets trapped in the "interstices", or the spaces between atoms. In contrast, amorphous materials have no "long-range order" (beyond the space of a few atoms in any direction), thus by definition are filled with defects.
When a defect occurs, depending on the type and material, it can create a hole, or a "trap". For example, a missing oxygen atom from a zinc oxide compound creates a hole in the lattice, surrounded by unbound zinc-atoms. This creates a net force or attraction that can be measured in electron-volts. When a high-energy photon strikes one of the zinc atoms, its electron absorbs the photon and is thrown out into a higher orbit. The electron may then enter the trap and be held in place (out of its normal orbit) by the attraction. To trigger the release of the energy, a random spike in thermal energy is needed of sufficient magnitude to boost the electron out of the trap and back into its normal orbit. Once in orbit, the electron's energy can drop back to normal (ground state) resulting in the release of a photon.
The release of energy in this way is a completely random process, governed mostly by the average temperature of the material versus the "depth" of the trap, or how many electron-volts it exerts. A trap that has a depth of 2.0 electron-volts would require a great amount of thermal energy (very high temperatures) to overcome the attraction, while at a depth of 0.1 electron-volts very little heat (very cold temperatures) are needed for the trap to even hold an electron. Higher temperatures may cause the faster release of energy, resulting in a brighter yet short-lived emission, while lower temperatures may produce dimmer but longer-lasting glows. Temperatures that are too hot or cold, depending on the substance, may not allow the accumulation or release of energy at all. The ideal depth of trap for persistent phosphorescence at room temperature is typically between 0.6 and 0.7 electron-volts. If the phosphorescent quantum yield is high, that is, if the substance has a large number of traps of the correct depth, these substances will release significant amounts of light over long time scales, creating so-called "glow in the dark" materials.
Persistent phosphorescence is the mechanism of most anything commonly referred to as glow in the dark. Typical uses include toys, frisbees and balls, safety signs, paints and markings, make-ups, art and décor, and a variety of other uses. | 0 | Theoretical and Fundamental Chemistry |
PAC has 2 loxP sites, which can be used by phage recombinases to form the product from its cre-gene recognition during Cre-Lox recombination. This process circularizes the DNA strand, forming a plasmid, which can then be inserted into bacteria such as Escherichia coli. The transformation is usually done by electroporation, which uses electricity to allow the plasmids permeate into the cells. If high expression levels are desired, the P1 lytic replicon can be used in constructs. Electroporation allows for lysogeny of PACs so that they can replicate within cells without disturbing other chromosomes. | 1 | Applied and Interdisciplinary Chemistry |
All these analyses pointed out even that there are some elephant families friendlier than others and showed how there are dominant families that settle down in the best places, where there is plenty of food and water. | 0 | Theoretical and Fundamental Chemistry |
Plasmids are known to have very similar structure when under control of Iterons. This structure consists of an origin of replication upstream of a gene that codes for a replication initiator protein. The iterons themselves are known to cover about half of the origin of replication. Usually, iterons on the same plasmid are highly conserved, whereas comparing iterons on different plasmids still exhibit homology yet are not as highly conserved. This suggests that iterons could be evolutionarily related. | 1 | Applied and Interdisciplinary Chemistry |
Sludge bulking can occur which makes activated sludge difficult to settle and frequently has an adverse impact on final effluent quality. Treating sludge bulking and managing the plant to avoid a recurrence requires skilled management and may require full-time staffing of a works to allow immediate intervention.
The discharge of toxic industrial pollution to treatment plants designed primarily to treat domestic sewage can create process upsets. | 1 | Applied and Interdisciplinary Chemistry |
End sequence profiling (ESP) can be used to detect structural variations such as insertions, deletions, and chromosomal rearrangement. Compare to other methods that look at chromosomal abnormalities, ESP is particularly useful to identify copy neutral abnormalities such as inversions and translocations that would not be apparent when looking at copy number variation. From the BAC library, both ends of the inserted fragments are sequenced using a sequencing platform. Detection of variations is then achieved by mapping the sequenced reads onto a reference genome. | 1 | Applied and Interdisciplinary Chemistry |
In the neighborhood of the origin, , Chandrasekhar provided an asymptotic expansion as
where . He also provided numerical solutions for the range . | 1 | Applied and Interdisciplinary Chemistry |
The research communities of vertebrate model organisms have adopted guidelines whereby genes in these species are given, whenever possible, the same names as their human orthologs. The use of prefixes on gene symbols to indicate species (e.g., "Z" for zebrafish) is discouraged. The recommended formatting of printed gene and protein symbols varies between species. | 1 | Applied and Interdisciplinary Chemistry |
This is the fourth member of the polyoxidanes. The first three are water [(mon)oxidane], hydrogen peroxide (dioxidane), and trioxidane. Tetroxidane is more unstable than the previous compounds. The term "tetraoxidane" extends beyond the parent compound to several daughter compounds of the general formula , where R can be hydrogen, halogen atoms, or various inorganic and organic monovalent radicals. The two Rs together can be replaced by a divalent radical, so heterocyclic tetroxidanes also exist. | 0 | Theoretical and Fundamental Chemistry |
Glide symmetry can be observed in nature among certain fossils of the Ediacara biota; the machaeridians; and certain palaeoscolecid worms. It can also be seen in many extant groups of sea pens.
In Conway's Game of Life, a commonly occurring pattern called the glider is so named because it repeats its configuration of cells, shifted by a glide reflection, after two steps of the automaton. After four steps and two glide reflections, the pattern returns to its original orientation, shifted diagonally by one unit. Continuing in this way, it moves across the array of the game. | 0 | Theoretical and Fundamental Chemistry |
Gravitational sinking of organisms (or the remains of organisms) transfers particulate organic carbon from the surface waters of the ocean to its deep interior. This process is known as the biological pump, and quantifying it is of interest to scientists because it is an important aspect of the Earths carbon cycle. Essentially, this is because carbon transported to the deep ocean is isolated from the atmosphere, allowing the ocean to act as a reservoir of carbon. This biological mechanism is accompanied by a physico-chemical mechanism known as the solubility pump which also acts to transfer carbon to the oceans deep interior.
Measuring the flux of sinking material (so-called marine snow) is usually done by deploying sediment traps which intercept and store material as it sinks down the water column. However, this is a relatively difficult process, since traps can be awkward to deploy or recover, and they must be left in situ over a long period to integrate the sinking flux. Furthermore, they are known to experience biases and to integrate horizontal as well as vertical fluxes because of water currents. For this reason, scientists are interested in ocean properties that can be more easily measured, and that act as a proxy for the sinking flux. The f-ratio is one such proxy. | 0 | Theoretical and Fundamental Chemistry |
MLSS (g/L) = SV [mL/L]/SVI [mL/g] or SVI [mL/g] = SV30 [mL/L]/MLSS (g/L)
Where:<br />
SVI = sludge volume index (mL/g)<br />
SV30 = Volume of settled solids per 1 litre after 30 minutes
In fact SVI is a calculation from two analyses : SV30 and MLSS.
0=(Q+Q)(X)-(QX+QX')
Where: <br />
Q = wastewater flow rate (m/d)<br />
Q = return sludge flow rate (m/d)<br />
X' = MLSS (kg/m)<br />
X' = return sludge concentration (kg/m)<br />
Q = sludge surplus (or excess) flow rate (m/d)<br />
This equilibrium formula for settling tanks is mostly calculated for the initial flows in m3/h.
This formula describes that the incoming amount of MLSS in a settler should be equivalent to the outcoming amount of MLSS via the return sludge flow. This equilibrium is only valid if the effluent water contains a low concentration in suspended solids. In normal conditions the excess amount is very low in comparison to the return amount, and for that reason many times the excess amount is neglected.
In that case the formula will be : (Q+Q)(X) = (QX) | 0 | Theoretical and Fundamental Chemistry |
The sterically encumbered germylene ligand (Dipp)PH, where Dipp=2,6-iPrCH, was synthesized by the addition of PCl to DippLi-(OEt), followed by the addition of LiAlH. (Dipp)PH was added to PhCHK, which is combined with GeCl to provide (DippP)Ge. The synthesis resulted in dark red crystals suitable for x-ray crystallography. The identity of the compound was confirmed by elemental analysis, multinuclear NMR, and x-ray crystallography. This compound is stable in the absence of air and water. | 0 | Theoretical and Fundamental Chemistry |
Phytoplankton are mostly made up of lignin and cellulose, which are broken down by oxidative mechanism, which consume oxygen. | 0 | Theoretical and Fundamental Chemistry |
Droplet-based microfluidics is a subcategory of microfluidics in contrast with continuous microfluidics; droplet-based microfluidics manipulates discrete volumes of fluids in immiscible phases with low Reynolds number and laminar flow regimes. Interest in droplet-based microfluidics systems has been growing substantially in past decades. Microdroplets allow for handling miniature volumes (μl to fl) of fluids conveniently, provide better mixing, encapsulation, sorting, and sensing, and suit high throughput experiments. Exploiting the benefits of droplet-based microfluidics efficiently requires a deep understanding of droplet generation to perform various logical operations such as droplet manipulation, droplet sorting, droplet merging, and droplet breakup. | 1 | Applied and Interdisciplinary Chemistry |
Harry Clary Jones (11 November 1865 – 9 April 1916) was an American physical chemist and a professor of chemistry at Johns Hopkins University. He worked extensively on the chemistry of solutions. His textbook Elements of Physical Chemistry was influential in its day. In 1913, he published a vision of chemistry in his book A new era in chemistry in which he noted the gaps of contemporary chemistry and indicated directions for work. | 0 | Theoretical and Fundamental Chemistry |
Polyfluorenes often show both excimer and aggregate formation upon thermal annealing or when current is passed through them. Excimer formation involves the generation of dimerized units of the polymer which emit light at lower energies than the polymer itself. This hinders the use of polyfluorenes for most applications, including light-emitting diodes (LED). When excimer or aggregate formation occurs this lowers the efficiency of the LEDs by decreasing the efficiency of charge carrier recombination. Excimer formation also causes a red shift in the emission spectrum.
Polyfluorenes can also undergo decomposition. There are two known ways in which decomposition can occur. The first involves the oxidation of the polymer that leads to the formation of an aromatic ketone, quenching the fluorescence. The second decomposition process results in aggregation leading to a red-shifted fluorescence, reduced intensity, exciton migration and relaxation through excimers.
Researchers have attempted to eliminate excimer formation and enhance the efficiency of polyfluorenes by copolymerizing polyfluorene with anthracene and end-capping polyfluorenes with bulky groups which could sterically hinder excimer formation. Additionally, researchers have tried adding large substituents at the nine position of the fluorene in order to inhibit excimer and aggregate formation. Furthermore, researchers have tried to improve LEDs by synthesizing fluorene-triarylamine copolymers and other multilayer devices that are based on polyfluorenes that can be cross-linked. These have been found to have brighter fluorescence and reasonable efficiencies.
Aggregation has also been combated by varying the chemical structure. For example, when conjugated polymers aggregate, which is natural in the solid state, their emission can be self-quenched, reducing luminescent quantum yields and reducing luminescent device performance. In opposition to this tendency, researchers have used tri-functional monomers to create highly branched polyfluorenes which do not aggregate due to the bulkiness of the substituents. This design strategy has achieved luminescent quantum yields of 42% in the solid state.
This solution reduces the ease of processability of the material because branched polymers have increased chain entanglement and poor solubility.
Another problem commonly encountered by polyfluorenes is an observed broad green, parasitic emission which detracts from the color purity and efficiency needed for an OLED.
Initially attributed to excimer emission, this green emission has been shown to be due to the formation of ketone defects along the fluorene polymer backbone (oxidation of the nine position on the monomer) when there are incomplete substitution at the nine positions of the fluorene monomer. Routes to combat this involve ensuring full substitution of the monomer’s active site, or including aromatic substituents. These solutions may present structures that lack optimal bulkiness or may be synthetically difficult. | 0 | Theoretical and Fundamental Chemistry |
A Woods lamp is a diagnostic tool used in dermatology by which ultraviolet light is shone (at a wavelength of approximately 365 nanometers) onto the skin of the patient; a technician then observes any subsequent fluorescence. For example, porphyrins—associated with some skin diseases—will fluoresce pink. Though the technique for producing a source of ultraviolet light was devised by Robert Williams Wood in 1903 using "Woods glass", it was in 1925 that the technique was used in dermatology by Margarot and Deveze for the detection of fungal infection of hair. It has many uses, both in distinguishing fluorescent conditions from other conditions and in locating the precise boundaries of the condition. | 0 | Theoretical and Fundamental Chemistry |
Ionizing radiation has deterministic and stochastic effects on human health. Deterministic (acute tissue effect) events happen with certainty, with the resulting health conditions occurring in every individual who received the same high dose. Stochastic (cancer induction and genetic) events are inherently random, with most individuals in a group failing to ever exhibit any causal negative health effects after exposure, while an indeterministic random minority do, often with the resulting subtle negative health effects being observable only after large detailed epidemiology studies.
The use of the sievert implies that only stochastic effects are being considered, and to avoid confusion deterministic effects are conventionally compared to values of absorbed dose expressed by the SI unit gray (Gy). | 0 | Theoretical and Fundamental Chemistry |
Since 2008, there is a discussion about a hypothetical precursor state of the quark–gluon plasma, the so-called "Glasma", where the dressed particles are condensed into some kind of glassy (or amorphous) state, below the genuine transition between the confined state and the plasma liquid. This would be analogous to the formation of metallic glasses, or amorphous alloys of them, below the genuine onset of the liquid metallic state.
Although the experimental high temperatures and densities predicted as producing a quark–gluon plasma have been realized in the laboratory, the resulting matter does not behave as a quasi-ideal state of free quarks and gluons, but, rather, as an almost perfect dense fluid. Actually, the fact that the quark–gluon plasma will not yet be "free" at temperatures realized at present accelerators was predicted in 1984 as a consequence of the remnant effects of confinement. | 0 | Theoretical and Fundamental Chemistry |
Oxaziridines undergo cycloaddition reactions with heterocumulenes to afford a number of unique five membered heterocycles, as shown in the figure below. This reactivity is due to the strained three membered ring and weak N-O bond. | 0 | Theoretical and Fundamental Chemistry |
Transition metal complexes of thiocyanate describes coordination complexes containing one or more thiocyanate (SCN) ligands. The topic also includes transition metal complexes of isothiocyanate. These complexes have few applications but played significant role in the development of coordination chemistry. | 0 | Theoretical and Fundamental Chemistry |
The set of databases includes data from International Tables of Crystallography, Vol. A: Space-Group Symmetry, and the data of maximal subgroups of space groups as listed in International Tables of Crystallography, Vol. A1: Symmetry relations between space groups. A k-vector database with Brillouin zone figures and classification tables of the k-vectors for space groups is also available via the [http://www.cryst.ehu.es/cryst/get_kvec.html KVEC] tool. | 0 | Theoretical and Fundamental Chemistry |
EFDA has two locations, which each house a so-called Close Support Unit (CSU), responsible for part of EFDA's activities. The EFDA-CSU Garching is located in Garching, near Munich (Germany), and is hosted by the German [http://www.ipp.mpg.de/ Max-Planck Institut für Plasmaphysik]. [https://web.archive.org/web/20090723101818/http://www.jet.efda.org/ EFDA-CSU Culham] is hosted by the [http://www.ccfe.ac.uk/ CCFE] laboratory in Culham (UK), home of the Joint European Torus facilities.
A large number of scientists and engineers from the associated laboratories work together on different projects of EFDA. The main task of the Close Support Units is to ensure that these diverse activities are integrated in a coordinated European Fusion Programme.
The EFDA management consists of the EFDA Leader (Dr. Francesco Romanelli) and the EFDA-Associate Leader for JET (Dr. Francesco Romanelli). | 0 | Theoretical and Fundamental Chemistry |
Since the discovery of ribozymes that exist in living organisms, there has been interest in the study of new synthetic ribozymes made in the laboratory. For example, artificially produced self-cleaving RNAs with good enzymatic activity have been produced. Tang and Breaker isolated self-cleaving RNAs by in vitro selection of RNAs originating from random-sequence RNAs. Some of the synthetic ribozymes that were produced had novel structures, while some were similar to the naturally occurring hammerhead ribozyme.
In 2015, researchers at Northwestern University and the University of Illinois Chicago engineered a tethered ribosome that works nearly as well as the authentic cellular component that produces all the proteins and enzymes within the cell. Called Ribosome-T, or Ribo-T, the artificial ribosome was created by Michael Jewett and Alexander Mankin. The techniques used to create artificial ribozymes involve directed evolution. This approach takes advantage of RNA's dual nature as both a catalyst and an informational polymer, making it easy for an investigator to produce vast populations of RNA catalysts using polymerase enzymes. The ribozymes are mutated by reverse transcribing them with reverse transcriptase into various cDNA and amplified with error-prone PCR. The selection parameters in these experiments often differ. One approach for selecting a ligase ribozyme involves using biotin tags, which are covalently linked to the substrate. If a molecule possesses the desired ligase activity, a streptavidin matrix can be used to recover the active molecules.
Lincoln and Joyce used in vitro evolution to develop ribozyme ligases capable of self-replication in about an hour, via the joining of pre-synthesized highly complementary oligonucleotides.
Although not true catalysts, the creation of artificial self-cleaving riboswitches, termed aptazymes, has also been an active area of research. Riboswitches are regulatory RNA motifs that change their structure in response to a small molecule ligand to regulate translation. While there are many known natural riboswitches that bind a wide array of metabolites and other small organic molecules, only one ribozyme based on a riboswitch has been described: glmS. Early work in characterizing self-cleaving riboswitches was focused on using theophylline as the ligand. In these studies, an RNA hairpin is formed which blocks the ribosome binding site, thus inhibiting translation. In the presence of the ligand, in these cases theophylline, the regulatory RNA region is cleaved off, allowing the ribosome to bind and translate the target gene. Much of this RNA engineering work was based on rational design and previously determined RNA structures rather than directed evolution as in the above examples. More recent work has broadened the ligands used in ribozyme riboswitches to include thymine pyrophosphate. Fluorescence-activated cell sorting has also been used to engineering aptazymes. | 0 | Theoretical and Fundamental Chemistry |
Different species use a wide variety of chemical substances to send sexual signals. The first to be described chemically was bombykol, the silkworm moth's sex pheromone, which is a complex alcohol, (E,Z)-10,12-hexadecadienol, discovered in 1959. It is detected in the antennae of the male moth by a pheromone-binding protein which carries the bombykol to a receptor bound to the membrane of a nerve cell.
The chemicals used by other moths are species-specific. For example, the Eastern spruce budworm Choristoneura fumiferana female pheromones contain a 95:5 mix of E- and Z 11-tetradecenal aldehydes, while the sex pheromones of other species of spruce budworm contain acetates and alcohols.
Sexual development in the freshwater green alga Volvox is initiated by a glycoprotein pheromone. It is one of the most potent known biological effector molecules, as it can trigger sexual development at a concentration as low as 10 moles per litre. Kirk and Kirk showed that sex-inducing pheromone production can be triggered experimentally in somatic cells by heat shock. | 1 | Applied and Interdisciplinary Chemistry |
Penetration enhancers have been applied to improve the absorption of poorly permeable, hydrophilic drugs or macromolecules. Permeation enhancers that have been used successfully for oral drug development include medium-chain fatty acids like caprylic acid or caprate, or its amino acid ester like Salcaprozate sodium (SNAC). The above-mentioned permeation/penetration enhancers have a surfactant-like activity where they perturb the intestinal epithelium, promoting transcellular or paracellular absorption. | 1 | Applied and Interdisciplinary Chemistry |
Because the solvent fraction of dilbit typically comprises volatile aromatics like naptha and benzene, reasonably rapid carrier vaporization can be expected to follow an above-ground spill—ostensibly enabling timely intervention by leaving only a viscous residue that is slow to migrate. Effective protocols to minimize exposure to petrochemical vapours are well-established, and oil spilled from the pipeline would be unlikely to reach the aquifer unless incomplete remediation were followed by the introduction of another carrier (e.g. a series of torrential downpours).
The introduction of benzene and other volatile organic compounds (collectively BTEX) to the subterranean environment compounds the threat posed by a pipeline leak. Particularly if followed by rain, a pipeline breach would result in BTEX dissolution and equilibration of benzene in water, followed by percolation of the admixture into the aquifer. Benzene can cause many health problems and is carcinogenic with EPA Maximum Contaminant Level (MCL) set at 5 μg/L for potable water. Although it is not well studied, single benzene exposure events have been linked to acute carcinogenesis. Additionally, the exposure of livestock, mainly cattle, to benzene has been shown to cause many health issues, such as neurotoxicity, fetal damage and fatal poisoning.
The entire surface of an above-ground pipeline can be directly examined for material breach. Pooled petroleum is unambiguous, readily spotted, and indicates the location of required repairs. Because the effectiveness of remote inspection is limited by the cost of monitoring equipment, gaps between sensors, and data that requires interpretation, small leaks in buried pipe can sometimes go undetected
Pipeline developers do not always prioritize effective surveillance against leaks. Buried pipes draw fewer complaints. They are insulated from extremes in ambient temperature, they are shielded from ultraviolet rays, and they are less exposed to photodegradation. Buried pipes are isolated from airborne debris, electrical storms, tornadoes, hurricanes, hail, and acid rain. They are protected from nesting birds, rutting mammals, and stray buckshot. Buried pipe is less vulnerable to accident damage (e.g. automobile collisions) and less accessible to vandals, saboteurs, and terrorists. | 1 | Applied and Interdisciplinary Chemistry |
Minister for the Environment, Heritage and Local Government Dick Roche criticised the show for "portraying Irish people as barbaric". The accident scenario is considered outlandish. In addition, the Irish government are currently attempting through a court action to close the Sellafield nuclear plant; the topic of the programme may be regarded as being sub judice.
When attempting to stem leaks found in the Sellafield facility, an explosion occurs. This sets off a further chain of explosions in the HASTs (Highly Active Storage Tank), resulting in the release of a highly radioactive plume. A north-easterly wind carries this radioactive material over the Irish Sea, which hits Irelands eastern coast, particularly County Louth and the Dublin area (Irelands main population centre) causing widespread chaos.
The Radiological Protection Institute of Ireland also voiced criticisms at the time of airing, Dr Ann McGarry, chief executive of the Radiological Protection Institute of Ireland, said: The RPII was also concerned that the programme appeared to suggest that evacuation would be the appropriate response to an accident at Sellafield. With Dr. McGarry explaining that International best practice indicates that evacuation would not be required as Ireland is at sufficient distance from the British nuclear facilities, that radiation levels arising from an accident would never be sufficiently high to give rise to the effects displayed in the programme. | 0 | Theoretical and Fundamental Chemistry |
The condition relates activity coefficients in liquid phase to total pressure and the vapour pressures of pure components.
Azeotropes can form only when a mixture deviates from Raoults law, the equality of compositions in liquid phase and vapor phases, in vapour-liquid equilibrium and Daltons law the equality of pressures for total pressure being equal to the sum of the partial pressures in real mixtures.
In other words: Raoults law predicts the vapor pressures of ideal mixtures as a function of composition ratio. More simply: per Raoults law molecules of the constituents stick to each other to the same degree as they do to themselves. For example, if the constituents are X and Y, then X sticks to Y with roughly equal energy as X does with X and Y does with Y. A positive deviation from Raoults law results when the constituents have a disaffinity for each other – that is X sticks to X and Y to Y better than X sticks to Y. Because this results in the mixture having less total affinity of the molecules than the pure constituents, they more readily escape from the stuck-together phase, which is to say the liquid phase, and into the vapor phase. When X sticks to Y more aggressively than X does to X and Y does to Y, the result is a negative deviation from Raoults law. In this case because the molecules in the mixture are sticking together more than in the pure constituents, they are more reluctant to escape the stuck-together liquid phase.
When the deviation is great enough to cause a maximum or minimum in the vapor pressure versus composition function, it is a mathematical consequence that at that point, the vapor will have the same composition as the liquid, resulting in an azeotrope.
The adjacent diagram illustrates total vapor pressure of three hypothetical mixtures of constituents, X, and Y. The temperature throughout the plot is assumed to be constant. The center trace is a straight line, which is what Raoults law predicts for an ideal mixture. In general solely mixtures of chemically similar solvents, such as n-hexane with n-heptane, form nearly ideal mixtures that come close to obeying Raoults law. The top trace illustrates a nonideal mixture that has a positive deviation from Raoults law, where the total combined vapor pressure of constituents, X and Y, is greater than what is predicted by Raoults law. The top trace deviates sufficiently that there is a point on the curve where its tangent is horizontal. Whenever a mixture has a positive deviation and has a point at which the tangent is horizontal, the composition at that point is a positive azeotrope. At that point the total vapor pressure is at a maximum. Likewise the bottom trace illustrates a nonideal mixture that has a negative deviation from Raoult's law, and at the composition where tangent to the trace is horizontal there is a negative azeotrope. This is also the point where total vapor pressure is minimum. | 1 | Applied and Interdisciplinary Chemistry |
After ingestion, ethyl eicosapentaenoic acid (E-EPA) is metabolized to eicosapentaenoic acid (EPA). EPA is absorbed in the small intestine and enters circulation. Peak plasma concentration occurs about five hours after ingestion, and the half-life is about 89 hours. EPA is lipolyzed mostly in the liver. | 1 | Applied and Interdisciplinary Chemistry |
In the early 11th century, the Islamic medical philosopher Avicenna wrote extensively on many subjects including medicine. Forty of these treatises on medicine survive, and in the most famous one titled the Canon of Medicine he discusses "rising gas". Avicenna believed that digestive system dysfunction was responsible for the overproduction of gas in the gastrointestinal tract. He suggested lifestyle changes and a compound of herbal drugs for its treatment.
In 1497, Alessandro Benedetti viewed the stomach as an unclean organ separated off by the diaphragm. This view of the stomach and intestines as being base organs was generally held until the mid-17th century.
In the Renaissance of the 16th century, Leonardo da Vinci produced some early drawings of the stomach and intestines. He thought that the digestive system aided the respiratory system. Andreas Vesalius provided some early anatomical drawings of the abdominal organs in the 16th century.
In the middle of the 17th century, a Flemish physician Jan Baptist van Helmont offered the first chemical account of digestion which was later described as being very close to the later conceptualised enzyme.
In 1653, William Harvey described the intestines in terms of their length, their blood supply, the mesenteries, and fat (adenylyl cyclase).
In 1823, William Prout discovered hydrochloric acid in the gastric juice. In 1895, Ivan Pavlov described its secretion as being stimulated by a neurologic reflex with the vagus nerve having a crucial role. Black in the 19th century suggested an association of histamine with this secretion. In 1916, Popielski described histamine as a gastric secretagogue of hydrochloric acid.
William Beaumont was an army surgeon who in 1825, was able to observe digestion as it took place in the stomach. This was made possible by experiments on a man with a stomach wound that did not fully heal leaving an opening into the stomach. The churning motion of the stomach was described among other findings.
In the 19th century, it was accepted that chemical processes were involved in the process of digestion. Physiological research into secretion and the gastrointestinal tract was pursued with experiments undertaken by Claude Bernard, Rudolph Heidenhain and Ivan Pavlov.
The rest of the 20th century was dominated by research into enzymes. The first to be discovered was secretin by Ernest Starling in 1902, with ensuing results from John Edkins in 1905 who first suggested gastrin with its structure being determined in 1964. Andre Latarjet and Lester Dragstedt found a role for acetylcholine in the digestive system. In 1972, H2 receptor agonists were described by J. Black, that block the action of histamine and decrease the production of hydrochloric acid. In 1980, proton pump inhibitors were described by Sachs. In 1983, the role of Helicobacter pylori in the formation of ulcers was described by Barry Marshall, and Robin Warren.
Art historians have often noted that banqueters on iconographic records of ancient Mediterranean societies almost always appear to be lying down on their left sides. One possible explanation could lie in the anatomy of the stomach and in the digestive mechanism. When lying on the left, the food has room to expand because the curvature of the stomach is enhanced in that position. | 1 | Applied and Interdisciplinary Chemistry |
The Kröhnke method is featured in a solvent-free synthesis of triarylpyridines that proceeds via a homo-coupling of two diaryl substituted α, β-unsaturated carbonyl compounds. This strategy offers a facile means for preparation of pyridnyl aryl systems that are important fragments of many useful drug scaffolds.
In 1992, Robinson and co-workers developed a similar pyridine synthesis using enamino nitriles as one of the three-carbon fragments in place of an α-pyridinium methyl ketone. This improvement increases the reactivity of the system and allows for formation of fully substituted pyridines whereas use of an α-pyridinium methyl ketone requires that the 3- or 5- position on the resulting pyridine be unsubstituted. Kröhnke condensation of enamino nitrile 20 with enone 21 yielded fused pyridine 22.
The mechanism of this Kröhnke-type reaction likely proceeds via a vinylogous cyanamide 23 which undergoes elimination of hydrocyanic acid, deprotonation to form enamine 24 and cyclization to form intermediate 25, which is then dehydrated to form the desired pyridine product.
A clean one-pot Kröhnke method in aqueous media generates 4’-aryl-2,2’:6’, 2’’-terpyridines. Reaction of aryl aldehyde 26 with two equivalents of 2-acetylpyridine (27) yielded terpyridines of the form 28.
In addition to variations on the original method, a number of combinatorial studies using the Kröhnke synthesis and its variations have been employed to synthesize vast libraries of highly functionalized pyridines. Janda and co-workers utilized the general Kröhnke reaction scheme to generate a 220 compound library. Various methyl ketones 29 and aldehydes 30 were coupled via aldol condensation to give enones of the form 31. These compounds were then reacted with various α-pyridinium methyl ketones 32 to give the desired tri-substituted pyridine 33.
In 2009, Tu and coworkers developed a 3 fragment, one-pot combinatorial strategy for developing 3-cyanoterpyridines 34and 1-amino-2-acylterpyridines 35. These combinatorial variations of the Kröhnke reaction provide an efficient synthetic strategy to poly arylpyridine scaffolds. This methodology would also be advantageous for biological assays and screening experiments. | 0 | Theoretical and Fundamental Chemistry |
The Dean number appears in the so-called Dean equations. These are an approximation to the full Navier–Stokes equations for the steady axially uniform flow of a Newtonian fluid in a toroidal pipe, obtained by retaining just the leading order curvature effects (i.e. the leading-order equations for ).
We use orthogonal coordinates with corresponding unit vectors aligned with the centre-line of the pipe at each point. The axial direction is , with being the normal in the plane of the centre-line, and the binormal. For an axial flow driven by a pressure gradient , the axial velocity is scaled with . The cross-stream velocities are scaled with , and cross-stream pressures with . Lengths are scaled with the tube radius .
In terms of these non-dimensional variables and coordinates, the Dean equations are then
where
is the convective derivative.
The Dean number De is the only parameter left in the system, and encapsulates the leading order curvature effects. Higher-order approximations will involve additional parameters.
For weak curvature effects (small De), the Dean equations can be solved as a series expansion in De. The first correction to the leading-order axial Poiseuille flow is a pair of vortices in the cross-section carrying flow from the inside to the outside of the bend across the centre and back around the edges. This solution is stable up to a critical Dean number . For larger De, there are multiple solutions, many of which are unstable. | 1 | Applied and Interdisciplinary Chemistry |
Atmospheric dynamics is the study of motion systems of meteorological importance, integrating observations at multiple locations and times and theories. Common topics studied include diverse phenomena such as thunderstorms, tornadoes, gravity waves, tropical cyclones, extratropical cyclones, jet streams, and global-scale circulations. The goal of dynamical studies is to explain the observed circulations on the basis of fundamental principles from physics. The objectives of such studies incorporate improving weather forecasting, developing methods for predicting seasonal and interannual climate fluctuations, and understanding the implications of human-induced perturbations (e.g., increased carbon dioxide concentrations or depletion of the ozone layer) on the global climate. | 1 | Applied and Interdisciplinary Chemistry |
2-Oxoadipic acid, also known as α-ketoadipic acid, is an intermediate in the metabolism of lysine and tryptophan. The conjugate base and carboxylate is 2-oxoadipate or α-ketoadipate, which is the biochemically relevant form. | 1 | Applied and Interdisciplinary Chemistry |
Plants respond and adapt to environmental factors, such as light and mechanical stress from wind. Leaves need to support their own mass and align themselves in such a way as to optimize their exposure to the sun, generally more or less horizontally. However, horizontal alignment maximizes exposure to bending forces and failure from stresses such as wind, snow, hail, falling debris, animals, and abrasion from surrounding foliage and plant structures. Overall leaves are relatively flimsy with regard to other plant structures such as stems, branches and roots.
Both leaf blade and petiole structure influence the leaf's response to forces such as wind, allowing a degree of repositioning to minimize drag and damage, as opposed to resistance. Leaf movement like this may also increase turbulence of the air close to the surface of the leaf, which thins the boundary layer of air immediately adjacent to the surface, increasing the capacity for gas and heat exchange, as well as photosynthesis. Strong wind forces may result in diminished leaf number and surface area, which while reducing drag, involves a trade off of also reducing photosynthesis. Thus, leaf design may involve compromise between carbon gain, thermoregulation and water loss on the one hand, and the cost of sustaining both static and dynamic loads. In vascular plants, perpendicular forces are spread over a larger area and are relatively flexible in both bending and torsion, enabling elastic deforming without damage.
Many leaves rely on hydrostatic support arranged around a skeleton of vascular tissue for their strength, which depends on maintaining leaf water status. Both the mechanics and architecture of the leaf reflect the need for transportation and support. Read and Stokes (2006) consider two basic models, the "hydrostatic" and "I-beam leaf" form (see Fig 1). Hydrostatic leaves such as in Prostanthera lasianthos are large and thin, and may involve the need for multiple leaves rather single large leaves because of the amount of veins needed to support the periphery of large leaves. But large leaf size favors efficiency in photosynthesis and water conservation, involving further trade offs. On the other hand, I-beam leaves such as Banksia marginata involve specialized structures to stiffen them. These I-beams are formed from bundle sheath extensions of sclerenchyma meeting stiffened sub-epidermal layers. This shifts the balance from reliance on hydrostatic pressure to structural support, an obvious advantage where water is relatively scarce.
Long narrow leaves bend more easily than ovate leaf blades of the same area. Monocots typically have such linear leaves that maximize surface area while minimising self-shading. In these a high proportion of longitudinal main veins provide additional support. | 0 | Theoretical and Fundamental Chemistry |
The SAT Subject Test in Chemistry was a one-hour multiple choice test given on chemistry by The College Board. A student chose whether to take the test depending upon college entrance requirements for the schools in which the student was planning to apply. Until 1994, the SAT Subject Tests were known as Achievement Tests; until January 2005, they were known as SAT 2s; they are still well known by the latter name. On January 19 2021, the College Board discontinued all SAT Subject tests, including the SAT Subject Test in Chemistry. This was effective immediately in the United States, and the tests were to be phased out by the following summer for international students. This was done as a response to changes in college admissions due to the impact of the COVID-19 pandemic on education. | 1 | Applied and Interdisciplinary Chemistry |
A thiosemicarbazone is an organosulfur compound with the formula HNC(S)NHN=CR. Many variations exist, including those where some or all of the NH centers are substituted by organic groups. Thiosemicarbazones are usually produced by condensation of a thiosemicarbazide with an aldehyde or ketone:
: HNC(S)NHNH + O=CR → HNC(S)NHN=CR + HO
In terms of their chemical structures, the CSN3 core atoms are coplanar. | 0 | Theoretical and Fundamental Chemistry |
Tristructural-isotropic (TRISO) fuel is a type of micro-particle fuel. A particle consists of a kernel of UO fuel (sometimes UC or UCO), which has been coated with four layers of three isotropic materials deposited through fluidized chemical vapor deposition (FCVD). The four layers are a porous buffer layer made of carbon that absorbs fission product recoils, followed by a dense inner layer of protective pyrolytic carbon (PyC), followed by a ceramic layer of SiC to retain fission products at elevated temperatures and to give the TRISO particle more structural integrity, followed by a dense outer layer of PyC. TRISO particles are then encapsulated into cylindrical or spherical graphite pellets. TRISO fuel particles are designed not to crack due to the stresses from processes (such as differential thermal expansion or fission gas pressure) at temperatures up to 1600 °C, and therefore can contain the fuel in the worst of accident scenarios in a properly designed reactor. Two such reactor designs are the prismatic-block gas-cooled reactor (such as the GT-MHR) and the pebble-bed reactor (PBR). Both of these reactor designs are high temperature gas reactors (HTGRs). These are also the basic reactor designs of very-high-temperature reactors (VHTRs), one of the six classes of reactor designs in the Generation IV initiative that is attempting to reach even higher HTGR outlet temperatures.
TRISO fuel particles were originally developed in the United Kingdom as part of the Dragon reactor project. The inclusion of the SiC as diffusion barrier was first suggested by D. T. Livey. The first nuclear reactor to use TRISO fuels was the Dragon reactor and the first powerplant was the THTR-300. Currently, TRISO fuel compacts are being used in some experimental reactors, such as the HTR-10 in China and the high-temperature engineering test reactor in Japan. In the United States, spherical fuel elements utilizing a TRISO particle with a UO and UC solid solution kernel are being used in the Xe-100, and Kairos Power is developing a 140 MWE nuclear reactor that uses TRISO. | 0 | Theoretical and Fundamental Chemistry |
He was born on April 1, 1917, in Fukuoka Prefecture, Japan. He died on April 16, 2001, at his home in Las Vegas, Nevada. | 0 | Theoretical and Fundamental Chemistry |
Several hormones can affect insulin secretion. Estrogen is correlated with an increase of insulin secretion by depolarizing the β-cells membrane and enhancing the entry of Ca+2. In contrast, growth hormone is known to lower the serum level of insulin by promoting the production of insulin-like growth factor-I (IGF-I). IGF-I, in turn, suppresses the insulin secretion. | 1 | Applied and Interdisciplinary Chemistry |
Random coil index (RCI) predicts protein flexibility by calculating an inverse weighted average of backbone secondary chemical shifts and predicting values of model-free order parameters as well as per-residue RMSD of NMR and molecular dynamics ensembles from this parameter.
The key advantages of this protocol over existing methods of studying protein flexibility are
# it does not require prior knowledge of a protein's tertiary structure,
# it is not sensitive to the protein's overall tumbling and
# it does not require additional NMR measurements beyond the standard experiments for backbone assignments.
The application of secondary chemical shifts to characterize protein flexibility is based on an assumption that the proximity of chemical shifts to random coil values is a manifestation of increased protein mobility, while significant differences from random coil values are an indication of a relatively rigid structure.
Even though chemical shifts of rigid residues may adopt random coil values as a result of comparable contributions of shielding and deshielding effects (e.g. from torsion angles, hydrogen bonds, ring currents, etc.), combining the chemical shifts from multiple nuclei into a single parameter allows one to decrease the influence of these flexibility false positives. The improved performance originates from the different probabilities of random coil chemical shifts from different nuclei being found among amino acid residues in flexible regions versus rigid regions. Typically, residues in rigid helices or rigid beta-strands are less likely to have more than one random coil chemical shift among their backbone shifts than residues in mobile regions.
The actual calculation of the RCI involves several additional steps including the smoothing of secondary shifts over several adjacent residues, the use of neighboring residue corrections, chemical shift re-referencing, gap filling, chemical shift scaling and numeric adjustments to prevent divide-by-zero problems. 13C, 15 N and 1H secondary chemical shifts are then scaled to account for the characteristic resonance frequencies of these nuclei and to provide numeric consistency among different parts of the protocol. Once these scaling corrections have been done, the RCI is calculated. The ‘‘end-effect correction’’ can also be applied at this point. The last step of the protocol involves smoothing the initial set of RCI values by three-point averaging. | 0 | Theoretical and Fundamental Chemistry |
While there is a national policy in the United States regarding mold, each state is responsible for independently creating and administering its policy. For example, following Hurricane Harvey, the governor of Texas sought to expand the emergency response to allow mold-remediation companies to come from out of state.
Under Section 17920.3 of the California Health & Safety Code, visible mold growth and dampness of habitable rooms can be sufficient for a home to be declared as a "substandard building", offering legal recourse for those affected, such as tenants in moldy apartments. Notably, California recognizes by law not only that dampness and mold exacerbate asthma but can cause its development. | 1 | Applied and Interdisciplinary Chemistry |
Carbohydrates are reactants in many organic reactions. For example:
* Cyanohydrin reaction
* Lobry-de Bruyn-van Ekenstein transformation
* Amadori rearrangement
* Wohl degradation
* Tipson-Cohen reaction
* Ferrier rearrangement
* Ferrier II reaction | 0 | Theoretical and Fundamental Chemistry |
Chromosome jumping is a tool of molecular biology that is used in the physical mapping of genomes. It is related to several other tools used for the same purpose, including chromosome walking.
Chromosome jumping is used to bypass regions difficult to clone, such as those containing repetitive DNA, that cannot be easily mapped by chromosome walking, and is useful in moving along a chromosome rapidly in search of a particular gene. Unlike chromosome walking, chromosome jumping is able to start on one point of the chromosome in order to traverse potential distant point of the same chromosome without cloning the intervening sequences. The ends of a large DNA fragment is the target cloning section of the chromosome jumping while the middle section gets removed by sequences of chemical manipulations prior to the cloning step. | 1 | Applied and Interdisciplinary Chemistry |
Nitrogen entering the euphotic zone is referred to as new nitrogen because it is newly arrived from outside the productive layer. The new nitrogen can come from below the euphotic zone or from outside sources. Outside sources are upwelling from deep water and nitrogen fixation. If the organic matter is eaten, respired, delivered to the water as ammonia, and re-incorporated into organic matter by phytoplankton it is considered recycled/regenerated production.
New production is an important component of the marine environment. One reason is that only continual input of new nitrogen can determine the total capacity of the ocean to produce a sustainable fish harvest. Harvesting fish from regenerated nitrogen areas will lead to a decrease in nitrogen and therefore a decrease in primary production. This will have a negative effect on the system. However, if fish are harvested from areas of new nitrogen the nitrogen will be replenished. | 1 | Applied and Interdisciplinary Chemistry |
Particular disadvantages of the powder technology include:
# 100% sintered (iron ore) cannot be charged in the blast furnace
# sintering cannot create uniform sizes
# micro- and nanostructures produced before sintering are often destroyed. | 1 | Applied and Interdisciplinary Chemistry |
In the direct enantiomer separation the most popular approach is use of chiral stationary phases. In this case the site of the chiral selector is on the stationary phase. Stationary phase consist of an inert solid support (usually silica microparticles) on to the surface of which a single enantiomer of a chiral molecule (selector) is either coated/adsorbed or chemically linked and that forms the chiral stationary phase. Commonly used chiral selectors include polysaccharides, proteins, cyclodextrins, etc. An interesting review of chiral stationary phase development and application in chiral analysis appeared in [https://www.chromatographyonline.com/view/review-chiral-stationary-phase-development-and-chiral-applications LCGC] magazine, 2011. | 0 | Theoretical and Fundamental Chemistry |
Berberine bridge enzyme (BBE) is a central enzyme in the biosynthesis of berberine, a pharmaceutically important alkaloid. The enzyme itself hasn't had extensive research carried on, and has very limited, if any, specific medical application. On the other hand, berberine is highly regarded for its interactions with several diseases. Berberine has been known to influence weight loss, and this antiobesity effect may benefit all conditions related to increased body mass such as hypertension, dyslipidemia or pre-diabetes. This may reduce the likelihood of getting sedentary diseases such as heart failure or other problems related to this issue. By being an AMPK activator like Metformin, it acts similar, affecting metabolism in a way that may reveal useful applications to treat type-2 diabetes.
Overall, this alkaloid might be useful in the treatment and study of diseases like polycystic ovary syndrome (PCOS), some types of cancer, heart problems or dyslipidemia. | 1 | Applied and Interdisciplinary Chemistry |
In fluid dynamics, drag crisis (also known as the Eiffel paradox) is a phenomenon in which drag coefficient drops off suddenly as Reynolds number increases. This has been well studied for round bodies like spheres and cylinders. The drag coefficient of a sphere will change rapidly from about 0.5 to 0.2 at a Reynolds number in the range of 300000. This corresponds to the point where the flow pattern changes, leaving a narrower turbulent wake. The behavior is highly dependent on small differences in the condition of the surface of the sphere. | 1 | Applied and Interdisciplinary Chemistry |
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