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The cytoplasmic polyhedrosis viruses (CPVs) form the genus Cypovirus of the family Reoviridae. CPVs are classified into 14 species based on the electrophoretic migration profiles of their genome segments. Cypovirus has only a single capsid shell, which is similar to the orthoreovirus inner core. CPV exhibits striking capsid stability and is fully capable of endogenous RNA transcription and processing. The overall folds of CPV proteins are similar to those of other reoviruses. However, CPV proteins have insertional domains and unique structures that contribute to their extensive intermolecular interactions. The CPV turret protein contains two methylase domains with a highly conserved helix-pair/β-sheet/helix-pair sandwich fold but lacks the β-barrel flap present in orthoreovirus λ2. The stacking of turret protein functional domains and the presence of constrictions and A spikes along the mRNA release pathway indicate a mechanism that uses pores and channels to regulate the highly coordinated steps of RNA transcription, processing, and release. | 1 | Biochemistry |
Bioretrosynthesis is a technique for synthesizing organic chemicals from inexpensive precursors and evolved enzymes. The technique builds on the retro-evolution hypothesis proposed in 1945 by geneticist Norman Horowitz. | 0 | Organic Chemistry |
At first, the PDE3s were purified and described as enzymes that hydrolyse both cGMP and cAMP with K values of 0.1–0.8 μM. However the V for cAMP hydrolysis is 4–10 times higher than V for cGMP hydrolysis.
When different PDEs were first identified, two types of PDEs (PDE3 and PDE4) that exhibited high affinities for cAMP were isolated. PDE3 exhibited high affinity for both cGMP and cAMP, but PDE4 had high affinity for only cAMP. For that reason, the PDE3 was called the cGMP-inhibited PDE to distinguish it from PDE4.
The 44-amino acid insertion in the catalytic domain of PDE3s is believed to be involved in PDE3's interaction with its substrate and inhibitors, but that remains to be established.
The proposed molecular mechanism of cyclic nucleotide specificity of PDEs is the so-called glutamine switch mechanism.
In the PDEs that have had their structure solved, there seems to be an invariant glutamine residue that stabilizes the binding of the purine ring in the active site (binding pocket). The g-amino group of the glutamine residue can alternatively adopt two different orientations:
# The hydrogen bond network supports guanine binding – cGMP selectivity
# The hydrogen bond network supports adenine binding – cAMP selectivity.
In PDEs that can hydrolyse both cGMP and cAMP (PDE3s), the glutamine can rotate freely and therefore switch between orientations. | 1 | Biochemistry |
Two types mannose-6-phosphate can recognize phosphorylated saccharide. One is cation-dependent and the other does not require cation to activate. | 0 | Organic Chemistry |
Aromatic nitriles are often prepared in the laboratory from the aniline via diazonium compounds. This is the Sandmeyer reaction. It requires transition metal cyanides. | 0 | Organic Chemistry |
The grain size, shape and distribution of the foundry sand, the type and quantity of bonding materials, the density to which the sand is rammed, and the percentage of moisture used for tempering the sand are important factors in regulating the degree of permeability. | 8 | Metallurgy |
In heap leaching processes, crushed (and sometimes agglomerated) ore is piled in a heap which is lined with an impervious layer. Leach solution is sprayed over the top of the heap, and allowed to percolate downward through the heap. The heap design usually incorporates collection sumps, which allow the "pregnant" leach solution (i.e. solution with dissolved valuable metals) to be pumped for further processing. An example is gold cyanidation, where pulverized ores are extracted with a solution of sodium cyanide, which, in the presence of air, dissolves the gold, leaving behind the nonprecious residue. | 8 | Metallurgy |
Bases: adenine (A), cytosine (C), guanine (G) and thymine (T) or uracil (U).
Amino acids: Alanine (Ala, A), Arginine (Arg, R), Asparagine (Asn, N), Aspartic acid (Asp, D), Cysteine (Cys, C), Glutamic acid (Glu, E), Glutamine (Gln, Q), Glycine (Gly, G), Histidine (His, H), Isoleucine (Ile, I), Leucine (Leu, L), Lysine (Lys, K), Methionine (Met, M), Phenylalanine (Phe, F), Proline (Pro, P), Serine (Ser, S), Threonine (Thr, T), Tryptophan (Trp, W), Tyrosine (Tyr, Y), Valine (Val, V) | 1 | Biochemistry |
The behavior of quantum dots (QDs) in solution and their interaction with other surfaces is of great importance to biological and industrial applications, such as optical displays, animal tagging, anti-counterfeiting dyes and paints, chemical sensing, and fluorescent tagging. However, unmodified quantum dots tend to be hydrophobic, which precludes their use in stable, water-based colloids. Furthermore, because the ratio of surface area to volume in a quantum dot is much higher than for larger particles, the thermodynamic free energy associated with dangling bonds on the surface is sufficient to impede the quantum confinement of excitons. Once solubilized by encapsulation in either a hydrophobic interior micelle or a hydrophilic exterior micelle, the QDs can be successfully introduced into an aqueous medium, in which they form an extended hydrogel network. In this form, quantum dots can be utilized in several applications that benefit from their unique properties, such as medical imaging and thermal destruction of malignant cancers. | 7 | Physical Chemistry |
One major complications to the use of herbicides for weed control is the ability of plants to evolve herbicide resistance, rendering the herbicides ineffective against target plants. Out of 31 known herbicide modes of action, weeds have evolved resistance to 21. 268 plant species are known to have evolved herbicide resistance at least once. Herbicide resistance was first observed in 1957, and since has evolved repeatedly in weed species from 30 families across the globe. Weed resistance to herbicides has become a major concern in crop production worldwide.
Resistance to herbicides is often attributed to overuse as well as the strong evolutionary pressure on the affected weeds. Three agricultural practices account for the evolutionary pressure upon weeds to evolve resistance: monoculture, neglecting non-herbicide weed control practices, and reliance on one herbicide for weed control. To minimize resistance, rotational programs of herbicide application, where herbicides with multiple modes of action are used, have been widely promoted. In particular, glyphosate resistance evolved rapidly in part because when glyphosate use first began, it was continuously and heavily relied upon for weed control. This caused incredibly strong selective pressure upon weeds, encouraging mutations conferring glyphosate resistance to persist and spread.
However, in 2015, an expansive study showed an increase in herbicide resistance as a result of rotation, and instead recommended mixing multiple herbicides for simultaneous application. As of 2023, the effectiveness of combining herbicides is also questioned, particularly in light of the rise of non-target site resistance.
Plants developed resistance to atrazine and to ALS-inhibitors relatively early, but more recently, glyphosate resistance has dramatically risen. Marestail is one weed that has developed glyphosate resistance. Glyphosate-resistant weeds are present in the vast majority of soybean, cotton and corn farms in some U.S. states. Weeds that can resist multiple other herbicides are spreading. Few new herbicides are near commercialization, and none with a molecular mode of action for which there is no resistance. Because most herbicides could not kill all weeds, farmers rotate crops and herbicides to stop the development of resistant weeds.
A 2008–2009 survey of 144 populations of waterhemp in 41 Missouri counties revealed glyphosate resistance in 69%. Weeds from some 500 sites throughout Iowa in 2011 and 2012 revealed glyphosate resistance in approximately 64% of waterhemp samples. As of 2023, 58 weed species have developed glyphosate resistance. Weeds resistant to multiple herbicides with completely different biological action modes are on the rise. In Missouri, 43% of waterhemp samples were resistant to two different herbicides; 6% resisted three; and 0.5% resisted four. In Iowa 89% of waterhemp samples resist two or more herbicides, 25% resist three, and 10% resist five.
As of 2023, Palmer amaranth with resistance to six different herbicide modes of action has emerged. Annual bluegrass collected from a golf course in the U.S. state of Tennessee was found in 2020 to be resistant to seven herbicides at once. Rigid ryegrass and annual bluegrass share the distinction of the species with confirmed resistance to the largest number of herbicide modes of action, both with confirmed resistance to 12 different modes of action; however, this number references how many forms of herbicide resistance are known to have emerged in the species at some point, not how many have been found simultaneously in a single plant.
In 2015, Monsanto released crop seed varieties resistant to both dicamba and glyphosate, allowing for use of a greater variety of herbicides on fields without harming the crops. By 2020, five years after the release of dicamba-resistant seed, the first example of dicamba-resistant Palmer amaranth was found in one location. | 2 | Environmental Chemistry |
Some common analytes that clinical chemistry tests analyze include:
;Electrolytes
*Sodium
*Potassium
*Chloride
*Bicarbonate
;Renal (kidney) function tests
*Creatinine
*Blood urea nitrogen
;Liver function tests
*Total protein (serum)
**Albumin
**Globulins
**A/G ratio (albumin-globulin)
**Protein electrophoresis
**Urine protein
*Bilirubin; direct; indirect; total
*Aspartate transaminase (AST)
*Alanine transaminase (ALT)
*Gamma-glutamyl transpeptidase (GGT)
*Alkaline phosphatase (ALP)
;Cardiac markers
*H-FABP
*Troponin
*Myoglobin
*CK-MB
*B-type natriuretic peptide (BNP)
;Minerals
*Calcium
*Magnesium
*Phosphate
*Potassium
;Blood disorders
*Iron
*Transferrin
*TIBC
*Vitamin B12
*Vitamin D
*Folic acid
;Miscellaneous
*Glucose
*C-reactive protein
*Glycated hemoglobin (HbA1c)
*Uric acid
*Arterial blood gases ([H], P</sub>)
*Adrenocorticotropic hormone (ACTH)
*Toxicological screening and forensic toxicology (drugs and toxins)
*Neuron-specific enolase (NSE)
*fecal occult blood test (FOBT) | 1 | Biochemistry |
A ninhydrin solution is commonly used by forensic investigators in the analysis of latent fingerprints on porous surfaces such as paper. The amino acids present in the minute sweat secretions that gather on the finger's unique ridges transfer to surfaces that are touched. Exposure of the surface to ninhydrin converts the amino acids into visibly colored products and thus reveals the print. The test solutions suffer from poor long-term stability, especially if not kept cold.
To further enhance the ability of ninhydrin, a solution of 1,2-indandione and zinc chloride (IND-Zn) can be used prior to ninhydrin. This sequence leads to greater overall reaction of the amino acids, possibly by IND-Zn helping to release them from the surface for the subsequent ninhydrin reaction. | 0 | Organic Chemistry |
An equilibrium constant is related to the standard Gibbs free energy of reaction change, , for the reaction by the expression
Therefore, K, must be a dimensionless number from which a logarithm can be derived. In the case of a simple equilibrium
the thermodynamic equilibrium constant is defined in terms of the activities, {AB}, {A} and {B}, of the species in equilibrium with each other:
Now, each activity term can be expressed as a product of a concentration and a corresponding activity coefficient, . Therefore,
When , the quotient of activity coefficients, is set equal to 1, we get
K then appears to have the dimension of 1/concentration. This is what usually happens in practice when an equilibrium constant is calculated as a quotient of concentration values. This can be avoided by dividing each concentration by its standard-state value (usually mol/L or bar), which is standard practice in chemistry.
The assumption underlying this practice is that the quotient of activities is constant under the conditions in which the equilibrium constant value is determined. These conditions are usually achieved by keeping the reaction temperature constant and by using a medium of relatively high ionic strength as the solvent. It is not unusual, particularly in texts relating to biochemical equilibria, to see an equilibrium constant value quoted with a dimension. The justification for this practice is that the concentration scale used may be either mol dm or mmol dm, so that the concentration unit has to be stated in order to avoid there being any ambiguity.
Note. When the concentration values are measured on the mole fraction scale all concentrations and activity coefficients are dimensionless quantities.
In general equilibria between two reagents can be expressed as
in which case the equilibrium constant is defined, in terms of numerical concentration values, as
The apparent dimension of this K value is concentration; this may be written as M or mM, where the symbol M signifies a molar concentration (). The apparent dimension of a dissociation constant is the reciprocal of the apparent dimension of the corresponding association constant, and vice versa.
When discussing the thermodynamics of chemical equilibria it is necessary to take dimensionality into account. There are two possible approaches.
# Set the dimension of to be the reciprocal of the dimension of the concentration quotient. This is almost universal practice in the field of stability constant determinations. The "equilibrium constant" , is dimensionless. It will be a function of the ionic strength of the medium used for the determination. Setting the numerical value of to be 1 is equivalent to re-defining the standard states.
# Replace each concentration term by the dimensionless quotient , where is the concentration of reagent in its standard state (usually 1 mol/L or 1 bar). By definition the numerical value of is 1, so also has a numerical value of 1.
In both approaches the numerical value of the stability constant is unchanged. The first is more useful for practical purposes; in fact, the unit of the concentration quotient is often attached to a published stability constant value in the biochemical literature. The second approach is consistent with the standard exposition of Debye–Hückel theory, where , etc. are taken to be pure numbers. | 7 | Physical Chemistry |
Prime editors may be used in gene drives. A prime editor may be incorporated into the Cleaver half of a Cleave and Rescue/ClvR system. In this case it is not meant to perform a precise alteration but instead to merely disrupt.
PE is among recently introduced technologies which allow the transfer of single-nucleotide polymorphisms (SNPs) from one individual crop plant to another. PE is precise enough to be used to recreate an arbitrary SNP in an arbitrary target, including deletions, insertions, and all 12 point mutations without also needing to perform a double-stranded break or carry a donating template. | 1 | Biochemistry |
Proteins that are to be targeted to a particular organelle or for secretion have an N-terminal signal peptide that directs the protein to its final destination. This signal peptide is removed by proteolysis after their transport through a membrane. | 1 | Biochemistry |
The theory is a powerful theoretical framework used to predict and analyze the intensities of electronic transitions within the 4f electron shell of rare-earth ions in solid-state materials. The transitions, which are parity forbidden in free ions, are made partially allowed in a solid matrix due to the effects of the crystal field. This field induces a mixing of electronic states, allowing transitions that would not occur in an isolated ion. The theory quantitatively describes this mixing using three phenomenological parameters, denoted as (where ). These parameters account for the asymmetric nature of the crystal field and enable the calculation of transition probabilities, oscillator strengths, and radiative lifetimes of excited states, which are crucial for the development of various photonic devices such as lasers and optical amplifiers.
The theory is named after Brian G. Judd and George S. Ofelt, who independently developed it in 1962. It has become a standard tool in the field of lanthanide spectroscopy, providing insights into the optical properties of rare earth-doped materials and aiding in the design of materials for color display systems, fluorescent lamps, and lasers. | 7 | Physical Chemistry |
* Quantification of analytes (e.g. proteins, peptides, DNA, nanoparticles) in complex solutions (e.g. plasma and fermentation broth )
* Determination of
** affinity constants
** binding kinetics
** molecular size (hydrodynamic radius)
**oligomeric state
** diffusion coefficient | 1 | Biochemistry |
After the expression of the gene product, it may be necessary to purify the expressed protein; however, separating the protein of interest from the great majority of proteins of the host cell can be a protracted process. To make this purification process easier, a purification tag may be added to the cloned gene. This tag could be histidine (His) tag, other marker peptides, or a fusion partners such as glutathione S-transferase or maltose-binding protein. Some of these fusion partners may also help to increase the solubility of some expressed proteins. Other fusion proteins such as green fluorescent protein may act as a reporter gene for the identification of successful cloned genes, or they may be used to study protein expression in cellular imaging. | 1 | Biochemistry |
The Geneva rules for nomenclature were described in 62 paragraphs. Some of these rules were:
* Saturated hydrocarbons would have names ending in -ane.
* The traditional names of the first 4 in the series was to be kept (methane, ethane, propane and butane)
* Longer chains were to have their names derived from the appropriate Greek numeral e.g. pent (pentane), hex (hexane) etc.
* When naming compounds with side chains the name would be determined by the longest straight chain with a substituted group e.g. methyl propane (CHCH(CH)CH)
* The endings ene and ine were indicative of the presence of a double and triple bond respectively.
* For closed chain hydrocarbons the term "cyclo" was to be used meaning what was known as hexamethylene (CH) would now be called cyclohexane | 0 | Organic Chemistry |
The protein CTCF plays a heavy role in repressing the insulin-like growth factor 2 gene, by binding to the H-19 imprinting control region (ICR) along with differentially-methylated region-1 (DMR1) and MAR3. | 1 | Biochemistry |
Peter Bernard David de la Mare (3 September 1920 – 13 December 1989) was a New Zealand physical organic chemist.
Born in Hamilton in 1920, he was the son of Sophia Ruth de la Mare (née Child), a medical practitioner, and Frederick Archibald de la Mare, a lawyer. He was educated at Hamilton High School, and then attended Victoria University College, from where he graduated in 1942 with an MSc in chemistry, winning the Shirtcliffe Fellowship and the Jacob Joseph Scholarship. His master's research was supervised by Philip Robertson. He worked at the Department of Scientific and Industrial Research in the agricultural department at Wellington and Ruakura, before undertaking PhD studies at University College London between 1946 and 1948, supervised by Christopher Ingold.
He was appointed as an assistant lecturer in the University College London department of chemistry in 1948, and was promoted to lecturer in 1949 and reader in 1957. In 1960 he moved to Bedford College, University of London, becoming professor and head of chemistry. He was appointed professor and head of chemistry at the University of Auckland in 1967, stepping down as head of department in 1980 and retiring in 1981.
De la Mare was awarded a DSc by thesis from the University of London in 1955. He was elected a Fellow of the Royal Society of New Zealand in 1970, and in 1985 he won the society's Hector Medal, then the highest award in New Zealand science. In 1983 he was awarded an honorary DSc by Victoria University of Wellington. | 0 | Organic Chemistry |
There are two Dutch assay offices located in the city of Gouda and Joure. The Dutch recognize platinum, gold, silver and palladium as precious metals. | 3 | Analytical Chemistry |
In the Atlantic Ocean, intermediate and deep waters are characterized by a lower content in DSi, compared to the modern Pacific and Southern Ocean. This lower interbasin difference in DSi has the effect of decreasing the preservation potential of opal in the Atlantic compared to its Pacific and Southern ocean counterparts. Atlantic DSi depleted waters tends to produce relatively less silicified organisms, which has a strong influence on the preservation of their frustules. This mechanism in best illustrated when comparing the Peru and northwest Africa upwelling systems. The dissolution/production ratio is much higher in the Atlantic upwelling than in the Pacific upwelling. This is due to the fact that coastal upwelling source waters are much richer in DSi off Peru, than off NW Africa. | 1 | Biochemistry |
Generally, the Koenigs–Knorr reaction refers to the use of glycosyl chlorides, bromides and more recently iodides as glycosyl donors. The Koenigs–Knorr reaction can be performed with alternative promoters such as various heavy metal salts including mercuric bromide/mercuric oxide, mercuric cyanide and silver triflate. When mercury salts are used, the reaction is normally called the Helferich method.
Other glycosidation methods are Fischer glycosidation, use of glycosyl acetates, thioglycosides, glycosyl trichloroacetimidates, glycosyl fluorides or n-pentenyl glycosides as glycosyl donors, or intramolecular aglycon delivery. | 0 | Organic Chemistry |
In stereochemistry, a stereocenter of a molecule is an atom (center), axis or plane that is the focus of stereoisomerism; that is, when having at least three different groups bound to the stereocenter, interchanging any two different groups creates a new stereoisomer. Stereocenters are also referred to as stereogenic centers.
A stereocenter is geometrically defined as a point (location) in a molecule; a stereocenter is usually but not always a specific atom, often carbon. Stereocenters can exist on chiral or achiral molecules; stereocenters can contain single bonds or double bonds. The number of hypothetical stereoisomers can be predicted by using 2, with n being the number of tetrahedral stereocenters; however, exceptions such as meso compounds can reduce the prediction to below the expected 2.
Chirality centers are a type of stereocenter with four different substituent groups; chirality centers are a specific subset of stereocenters because they can only have sp hybridization, meaning that they can only have single bonds. | 4 | Stereochemistry |
In 1971, just after what a later study would identify as the point when the lakes eutrophication began in earnest, M.C. Healey and W.L. Woodall, two researchers from the Fisheries Research Board of Canada, considered Frame in a limnological study of seven lakes in and around Yellowknife that their agency was considering as sites for an experimental fishery. Among the others studied were the larger Kam Lake to the south, and five others outside city limits. Their analysis, published in 1973, showed that while Frames water quality was still good enough to support the recreational use that was still occurring, there were already some signs of decline.
Chemical analysis of the water showed similarities to Kam Lake. Like the larger lake, it had a notably alkaline pH of 8.5, reflecting higher concentrations of salts, and a specific conductance of 332, well below Kam but around three times the values obtained for the other four lakes. Its calcium, magnesium, potassium, and sodium levels were higher than any other lake except Kam, and it had the highest bicarbonate levels at 132.4 mg/L. The lake was found to be generally isothermal, although its depths cooled significantly in August, when the later of two samples was taken. Plenty of oxygen was still in the water. The researchers attributed Frames high biochemical oxygen demand and "peculiar chemical characteristics" to not only the proximity of downtown but the citys use of the lake as a dump for plowed snow.
"Frame Lake had the most peculiar species assemblage for the region", the two wrote of the results of their zooplankton findings. Daphnia middendoffiana, the only Cladocera species found in Frame, was present in only that lake of the seven. Likewise, several copepods—Heterecope sententrionalis and Diaptomus pribilofensis and leptopus—were unique to Frame. Cyclops vernalis was the only species the lake shared with any of the others. "The species in Frame Lake are typical of a lake west of the continental divide, in Alaska or northern British Columbia, but extremely uncommon east of the divide", they observed.
Benthos species in Frame were more similar to the other lakes. Frame shared with the other lakes a high mollusk population, predominantly in the Sphaeriidae and Valvatidae families. Lymnaeidae were unique to it, however. Insect populations around the lake are dominated by non-biting midges, especially the Chironominae and Tanypodinae subfamilies. Healey and Woodall also found significant populations of mayflies, damselflies, and water boatmen in the lake.
They did not find any fish, the only one of the seven lakes where this was the case. Frame nevertheless recorded the highest biomass count of the seven lakes, 7.32 grams of dry weight per square meter of bed, more than three times the second highest reading, on the second of two sampling periods in summer 1971. At the same time, that biomass had the lowest ash content of any of the sampled lakes as well. | 2 | Environmental Chemistry |
A hybridization assay comprises any form of quantifiable hybridization i.e. the quantitative annealing of two complementary strands of nucleic acids, known as nucleic acid hybridization. | 1 | Biochemistry |
The fluorenylmethoxycarbonyl protecting group (Fmoc) is a base-labile protecting group used in organic synthesis. | 1 | Biochemistry |
Dopplerite is a naturally occurring organic substance found in amorphous, elastic or jelly-like masses, of brownish-black color, in peat beds in Styria and in Switzerland. It is tasteless, insoluble in alcohol and ether, and is described by James Dwight Dana as an acid substance, or mixture of different acids, related to humic acid. It is named after the physicist and mathematician Christian Doppler. | 9 | Geochemistry |
Identification, sampling and analysis of acid sulfate soils should be conducted in line with:
* the National acid sulfate soils sampling and identification methods manual;
* the National acid sulfate soils identification and laboratory methods manual; and
* the National Environment Protection (Assessment of Site Contamination) Measure 1999 (Cth) (Site Contamination NEPM).
The Site Contamination NEPM is not specific to acid sulfate soils and is not discussed here.
The national sampling and identification manual provides: background information on acid sulfate soil formation and disturbance processes and environmental impacts; the minimum requirements of a desktop assessment and site inspection; and a guide to sampling and field testing.
Key features of the national laboratory methods manual are:
* the action criteria triggering the need for an Acid Sulfate Soil Management Plan (ASSMP);
* a description of the key pools of actual and potential acidity; an overview of the hazards associated with the disturbance of acid sulfate soils (e.g., acidification, deoxygenation, and salinisation of soil/water systems, and mobilisation of metals/metalloids); and
* a description of the standard analytical techniques used to quantify these hazards (e.g., Acid Base Accounting, Acid Volatile Sulfide analysis, and sequential metal/metalloid extraction).
These manuals do not provide guidance on the management of acid sulfate soils. For topic-specific management strategies see:
* Guidance for the Dredging of Acid Sulfate Soil Sediments and Associated Dredge Spoil Management;
* Guidance for the Dewatering of Acid Sulfate Soils in Shallow Groundwater Environments; and
* Overview and Management of Monosulfidic Black Ooze (MBO) Accumulation in Waterways and Wetlands.
These documents are comprehensive and publicly available through the Water Quality Australia website. | 9 | Geochemistry |
The Baeyer–Drewsen indigo synthesis (1882) is an organic reaction in which indigo is prepared from 2-nitrobenzaldehyde and acetone The reaction was developed by von Baeyer in 1880 to produce the first synthetic indigo at laboratory scale. This procedure is not used at industrial scale.
The reaction is classified as an aldol condensation. As a practical route to indigo, this method was displaced by routes from aniline. | 0 | Organic Chemistry |
NADH:ubiquinone oxidoreductase complex assembly factor 6 is a protein that in humans is encoded by the NDUFAF6 gene. The protein is involved in the assembly of complex I in the mitochondrial electron transport chain. Mutations in the NDUFAF6 gene have been shown to cause Complex I deficiency, Leigh syndrome, and Acadian variant Fanconi Syndrome. | 1 | Biochemistry |
Depending upon the desired product, either the solvent or solute stream of RO will be waste. For food concentration applications, the concentrated solute stream is the product and the solvent stream is waste. For water treatment applications, the solvent stream is purified water and the solute stream is concentrated waste. The solvent waste stream from food processing may be used as reclaimed water, but there may be fewer options for disposal of a concentrated waste solute stream. Ships may use marine dumping and coastal desalination plants typically use marine outfalls. Landlocked RO plants may require evaporation ponds or injection wells to avoid polluting groundwater or surface runoff. | 3 | Analytical Chemistry |
The potential difference at each pole of the BPE (which may or may not be enough for electrochemical reactions).
Note that the solution potential is not directly controlled by a power source (e.g. potentiostat) because it depends also on the solution composition. Therefore, for electrons to transfer to reduce species in the solution, the potential of the working electrode need to be set to a value more negative than of an electroactive molecule in the solution, and then – depending on the kinetics – electrons may transfer. In similar fashion, oxidation reactions occur. Also, according to Ohm’s law, the electric field and solution potential (V) will increase with increasing solution resistivity and the applied current at the outer-circuit. | 7 | Physical Chemistry |
Before August 1993, LAAM was classified as a schedule I drug in the United States. LAAM is not approved for use in Australia and Canada. At present, it is a Schedule II Narcotic controlled substance in the United States with a DEA ACSCN of 9648 and a national aggregate annual manufacturing quota of 4 grammes as of 2013. | 4 | Stereochemistry |
Salt hydrates (MN·nHO)
*Advantages
** High volumetric latent heat storage capacity
** Availability and low cost
** Sharp melting point
** High thermal conductivity
** High heat of fusion
** Non-flammable
** Sustainability
* Disadvantages
** Difficult to prevent incongruent melting and phase separation upon cycling, which can cause a significant loss in latent heat enthalpy.
** Can be corrosive to many other materials, such as metals. This can be overcome by only using specific metal-PCM pairings or encapsulation in small quantities in non-reactive plastic.
** Change of volume is very high in some mixtures
** Super cooling can be a problem in solid–liquid transition, necessitating the use of nucleating agents which may become inoperative after repeated cycling | 7 | Physical Chemistry |
The final strategy focuses not on the deposition or removal of SAMS, but the modification of terminal groups. In the first case the terminal group can be modified to remove functionality so that SAM molecule will be inert. In the same regards the terminal group can be modified to add functionality so it can accept different materials or have different properties than the original SAM terminal group. The major techniques that use this strategy are:
* Focused electron beam and ultraviolet irradiation
:Exposure to electron beams and UV light changes the terminal group chemistry. Some of the changes that can occur include the cleavage of bonds, the forming of double carbon bonds, cross-linking of adjacent molecules, fragmentation of molecules, and confromational disorder.
* Atomic force microscope
:A conductive AFM tip can create an electrochemical reaction that can change the terminal group. | 6 | Supramolecular Chemistry |
Flaviviruses constitute a family of linear, single-stranded RNA(+) viruses. Flaviviruses include the West Nile virus, dengue virus, Tick-borne Encephalitis Virus, Yellow Fever Virus, and several other viruses. Many flavivirus species can replicate in both mammalian and insect cells. Most flaviviruses are arthropod borne and multiply in both vertebrates and arthropods. The viruses in this family that are of veterinary importance include Japanese encephalitis virus, St. Louis encephalitis virus, West Nile virus, Israel turkey meningoencephalomyelitis virus, Sitiawan virus, Wesselsbron virus, yellow fever virus and the tick-borne flaviviruses e.g. louping ill virus. | 1 | Biochemistry |
DCCC has been employed to separate a wide variety of phytochemicals from their crude extracts. The long list of natural product separations includes: saponins, alkaloids, senna glycosides, monosaccarides, triterpene glycosides, flavone glycosides, xanthones, iridoid glycosides, vitamin B, lignans, imbricatolic acid, gallic acid, carotenoids, and triterpenoids.
DCCC instruments have been commercially manufactured and distributed by Büchi and Tokyo Rikakikai (Eyela). | 3 | Analytical Chemistry |
Several pseudo-response regulators have been found in Selaginella, but their function has not yet been explored. | 1 | Biochemistry |
UV/Vis spectroscopy is widely used as a technique in chemistry to analyze chemical structure, the most notable one being conjugated systems. UV radiation is often used to excite a given sample where the fluorescent emission is measured with a spectrofluorometer. In biological research, UV radiation is used for quantification of nucleic acids or proteins. In environmental chemistry, UV radiation could also be used to detect Contaminants of emerging concern in water samples.
In pollution control applications, ultraviolet analyzers are used to detect emissions of nitrogen oxides, sulfur compounds, mercury, and ammonia, for example in the flue gas of fossil-fired power plants. Ultraviolet radiation can detect thin sheens of spilled oil on water, either by the high reflectivity of oil films at UV wavelengths, fluorescence of compounds in oil, or by absorbing of UV created by Raman scattering in water. UV absorbance can also be uesd to quantify contaminants in wastewater. Most commonly used 254 nm UV absorbance is genrally used as a surrogate parameters to quantify NOM. Another form of light-based detection method uses a wide spectrum of excitation emission matrix (EEM) to detect and identify contaminants based on their flourense properties. EEM could be used to discriminate different groups of NOM based on the difference in light emission and excitation of fluorophores. NOMs with certain molecular structures are reported to have fluorescent properties in a wide range of excitation/emission wavelengths.
Ultraviolet lamps are also used as part of the analysis of some minerals and gems. | 5 | Photochemistry |
C-reactive protein (CRP), a marker of systemic inflammation, is also increased in obstructive sleep apnea (OSA). CRP and interleukin-6 (IL-6) levels were significantly higher in patients with OSA compared to obese control subjects. Patients with OSA have higher plasma CRP concentrations that increased corresponding to the severity of their apnea-hypopnea index score. Treatment of OSA with CPAP (continuous positive airway pressure) significantly alleviated the effect of OSA on CRP and IL-6 levels. | 1 | Biochemistry |
QuEChERS is a solid phase extraction method for detection of biocide residues in food. The name is a portmanteau word formed from "quick, easy, cheap, effective, rugged, and safe".
__TOC__ | 3 | Analytical Chemistry |
RNA-targeting small molecules represent a class of small molecules, organic compounds with traditional drug properties (e.g., Lipinski's rule of five) that can bind to RNA secondary or tertiary structures and alter translation patterns, localization, and degradation. | 1 | Biochemistry |
The mitochondrial targeting signal also known as presequence is a 10-70 amino acid long peptide that directs a newly synthesized protein to the mitochondria. It is found at the N-terminus end consists of an alternating pattern of hydrophobic and positively charged amino acids to form what is called an amphipathic helix. Mitochondrial targeting signals can contain additional signals that subsequently target the protein to different regions of the mitochondria, such as the mitochondrial matrix or inner membrane. In plants, an N-terminal signal (or transit peptide) targets to the plastid in a similar manner. Like most signal peptides, mitochondrial targeting signals and plastid specific transit peptides are cleaved once targeting is complete. Some plant proteins have an N-terminal transport signal that targets both organelles often referred to as dual-targeted transit peptide. Approximately 5% of total organelle proteins are predicted to be dual-targeted however the specific number could be higher considering the variable degree of accumulation of passenger proteins in both organelles. The targeting specificity of these transit peptides depends on many factors including net charge and affinity between transit peptides and organelle transport machinery. | 1 | Biochemistry |
The hypothesized existence of an RNA world does not exclude a "Pre-RNA world", where a metabolic system based on a different nucleic acid is proposed to pre-date RNA. A candidate nucleic acid is peptide nucleic acid (PNA), which uses simple peptide bonds to link nucleobases. PNA is more stable than RNA, but its ability to be generated under prebiological conditions has yet to be demonstrated experimentally.
Threose nucleic acid (TNA) has also been proposed as a starting point, as has glycol nucleic acid (GNA), and like PNA, also lack experimental evidence for their respective abiogenesis.
An alternative—or complementary—theory of RNA origin is proposed in the PAH world hypothesis, whereby polycyclic aromatic hydrocarbons (PAHs) mediate the synthesis of RNA molecules. PAHs are the most common and abundant of the known polyatomic molecules in the visible Universe and are a likely constituent of the primordial sea. PAHs and fullerenes (also implicated in the origin of life) have been detected in nebulae.
The iron-sulfur world theory proposes that simple metabolic processes developed before genetic materials did, and these energy-producing cycles catalyzed the production of genes.
Some of the difficulties of producing the precursors on earth are bypassed by another alternative or complementary theory for their origin, panspermia. It discusses the possibility that the earliest life on this planet was carried here from somewhere else in the galaxy, possibly on meteorites similar to the Murchison meteorite. Sugar molecules, including ribose, have been found in meteorites. Panspermia does not invalidate the concept of an RNA world, but posits that this world or its precursors originated not on Earth but rather another, probably older, planet.
The relative chemical complexity of the nucleotide and the unlikelihood of it spontaneously arising, along with the limited number of combinations possible among four base forms, as well as the need for RNA polymers of some length before seeing enzymatic activity, have led some to reject the RNA world hypothesis in favor of a metabolism-first hypothesis, where the chemistry underlying cellular function arose first, along with the ability to replicate and facilitate this metabolism. | 9 | Geochemistry |
Drospirenone was patented in 1976 and introduced for medical use in 2000. Schering AG of Germany has been granted several patents on the production of drospirenone, including WIPO and US patents, granted in 1998 and 2000, respectively. It was introduced for medical use in combination with ethinylestradiol as a combined birth control pill in 2000. Drospirenone is sometimes described as a "fourth-generation" progestin based on its time of introduction. The medication was approved for use in menopausal hormone therapy in combination with estradiol in 2005. Drospirenone was introduced for use as a progestogen-only birth control pill in 2019. A combined birth control pill containing estetrol and drospirenone was approved in 2021. | 4 | Stereochemistry |
Another idea proposed was that ERVs from the same family played a role in recruiting multiple genes into the same network of regulation. It was found that MER41 elements provided addition redundant regulatory enhancement to the genes located near STAT1 binding sites. | 1 | Biochemistry |
Grasselli Brown has over ninety publications, nine books, and a patent in the field of infrared and Raman spectroscopy.
In 1985, she was selected as one of the Foremost Women of the 20th Century. She is the first woman to be inducted into the Hungarian and Austrian Chemical Societies.
In 2002, Grasselli Brown received the National Ellis Medal of Honor and was selected as an International Scientist of the Year.
In 1991, Grasselli Brown was the first woman to be inducted into the Ohio Science and Technology Hall of Fame. She was inducted into the Ohio Women's Hall of Fame in 1989 and is also a member of the Cleveland International Hall of Fame.
In 2004, Grasselli Brown was chosen to be a part of the book "Ohio 200 years, 200 Women: Ohio's First and Finest."
As of 2013, Jeanette Grasselli Brown donated her papers to the Mahn Center for Archives and Special Collections at her alma mater, Ohio University.
In 2022, a permanent exhibit at the Great Lakes Science Center, entitled "Interactive Periodic Table of Element", was created through a donation by the Northeastern Ohio Science & Engineering Fair, in honor of Dr. Jeanette Grasselli Brown and her husband Dr. Glenn Brown. | 3 | Analytical Chemistry |
A creamed emulsion increases the likelihood of coalescence due to the close proximity of the globules in the cream. Factors that influence the rate of creaming are similar to those involved in the sedimentation rate of suspension particles. Stokes Law is inadequate to predict creaming but can be used to identify these factors.
Creaming of an emulsion also increases the tendency of an emulsion to inversion. This class of process occurs mainly in special cases, when both the continuous and dispersed phases of an emulsion are liquid, as commonly is the state in dairy cream. It is common where the volume of the two fluid components is about the same or the volume of the dispersed phase is larger than that of the continuous phase. The process of emulsion inversion occurs when the dispersed droplets unite, but retain the formerly continuous material as droplets within the mass.
This is an "invert emulsion" or "inverted emulsion", in which the formerly continuous phase has become the dispersed phase and vice versa. Inversion happens in dairy cream when the butterfat concentration is too high and the resulting invert emulsion looks much like butter.
Commonly invert emulsions look much like a paste or thick cream and typical examples are mayonnaise, margarine (especially "low-fat" grades of margarine), pharmaceutical ointments, and cosmetic "creams".
Emulsion inversion differs from emulsion breaking in that a breaking emulsion tends to separate the two phases into un-emulsified continuous phases. Inversion of an emulsion may or may not be difficult to invert, but generally more difficult than creaming. | 7 | Physical Chemistry |
β-Fe and the A critical temperature are important in induction heating of steel, such as for surface-hardening heat treatments. Steel is typically austenitized at 900–1000 °C before it is quenched and tempered. The high-frequency alternating magnetic field of induction heating heats the steel by two mechanisms below the Curie temperature: resistance or Joule heating and ferromagnetic hysteresis losses. Above the A boundary, the hysteresis mechanism disappears and the required amount of energy per degree of temperature increase is thus substantially larger than below A. Load-matching circuits may be needed to vary the impedance in the induction power source to compensate for the change. | 8 | Metallurgy |
As a chiral derivatizing agent, it reacts with an alcohol or amine of unknown stereochemistry to form an ester or amide. The absolute configuration of the ester or amide is then determined by proton and/or F NMR spectroscopy.
Mosher's acid chloride, the acid chloride form, is sometimes used because it has better reactivity. | 4 | Stereochemistry |
In response to decreasing dissolved oxygen level in the environment, fish swim up to the surface of the water column and ventilate at the top layer of the water where it contains relatively higher level of dissolved oxygen, a behavior called aquatic surface respiration (ASR). Oxygen diffuses into water from air and therefore the top layer of water in contact with air contains more oxygen. This is true only in stagnant water; in running water all layers are mixed together and oxygen levels are the same throughout the water column. One environment where ASR often takes place is tidepools, particularly at night. Separation from the sea at low tide means that water is not renewed, fish crowding within the pool means that oxygen is quickly depleted, and absence of light at night means that there is no photosynthesis to replenish the oxygen. Examples of tidepool species that perform ASR include the tidepool sculpin, the three-spined stickleback, and the mummichog.
But ASR is not limited to the intertidal environment. Most tropical and temperate fish species living in stagnant waters engage in ASR during hypoxia. One study looked at 26 species representing eight families of non-air breathing fishes from the North American great plains, and found that all but four of them performed ASR during hypoxia. Another study looked at 24 species of tropical fish common to the pet trade, from tetras to barbs to cichlids, and found that all of them performed ASR. An unusual situation in which ASR is performed is during winter, in lakes covered by ice, at the interface between water and ice or near air bubbles trapped underneath the ice.
Some species may show morphological adaptations, such as a flat head and an upturned mouth, that allow them to perform ASR without breaking the water surface (which would make them more visible to aerial predators). One example is the mummichog, whose upturned mouth suggests surface feeding, but whose feeding habits are not particularly restricted to the surface. In the tambaqui, a South American species, exposure to hypoxia induces within hours the development of additional blood vessels inside the lower lip, enhancing its ability to take up oxygen during ASR. Swimming upside down may also help fishes perform ASR, as in some upside-down catfish.
Some species may hold an air bubble within the mouth during ASR. This may assist buoyancy as well as increase the oxygen content of the water passing over the bubble on its way to the gills. Another way to reduce buoyancy costs is to perform ASR on rocks or plants that provide support near the water surface.
ASR significantly affects survival of fish during severe hypoxia. In the shortfin molly for example, survival was approximately four times higher in individuals able to perform ASR as compared to fish not allowed to perform ASR during their exposure to extreme hypoxia.
ASR may be performed more often when the need for oxygen is higher. In the sailfin molly, gestating females (this species is a livebearer) spend about 50% of their time in ASR as compared to only 15% in non-gestating females under the same low levels of oxygen. | 9 | Geochemistry |
Some may use the terms biogeochemical cycle and geochemical cycle interchangeably because both cycles deal with Earth's reservoirs. However, a biogeochemical cycle refers to the chemical interactions in surface reservoirs such as the atmosphere, hydrosphere, lithosphere, and biosphere whereas a geochemical cycle refers to the chemical interactions that exist in crustal and sub crustal reservoirs such as the deep earth and lithosphere. | 9 | Geochemistry |
While the anomeric effect is a general explanation for this type of stabilization for a molecule, the type and amount of stabilization can be affected by the substituents being examined as well as the solvent being studied. | 7 | Physical Chemistry |
Let be the effective absorption cross-section be effective emission cross-sections at frequency , and let be the effective temperature of the medium. The McCumber relation is
where
is thermal steady-state ratio of populations; frequency is called "zero-line" frequency;
is the Planck constant and
is the Boltzmann constant. Note that the right-hand side of Equation (1) does not depend on . | 7 | Physical Chemistry |
In 1926, Raymond Pearl proposed that longevity varies inversely with basal metabolic rate (the "rate of living hypothesis"). Support for this hypothesis comes from the fact that mammals with larger body size have longer maximum life spans (large animals do have higher total metabolic rates, but the metabolic rate at the cellular level is much lower, and the breathing rate and heartbeat are slower in larger animals) and the fact that the longevity of fruit flies varies inversely with ambient temperature. Additionally, the life span of houseflies can be extended by preventing physical activity. This theory has been bolstered by several new studies linking lower basal metabolic rate to increased life expectancy, across the animal kingdom—including humans. Calorie restriction and reduced thyroid hormone levels, both of which decrease the metabolic rate, have been associated with higher longevity in animals.
However, the ratio of total daily energy expenditure to resting metabolic rate can vary between 1.6 and 8.0 between species of mammals. Animals also vary in the degree of coupling between oxidative phosphorylation and ATP production, the amount of saturated fat in mitochondrial membranes, the amount of DNA repair, and many other factors that affect maximum life span.
One problem with understanding the associations of lifespan and metabolism is that changes in metabolism are often confounded by other factors that may affect lifespan. For example under calorie restriction whole body metabolic rate goes down with increasing levels of restriction, but body temperature also follows the same pattern. By manipulating the ambient temperature and exposure to wind it was shown in mice and hamsters that body temperature is a more important modulator of lifespan than metabolic rate. | 1 | Biochemistry |
EPA issued a drinking water health advisory for MTBE, a guidance document for water utilities and the public, in 1997. The Agency first listed MTBE in 1998 as a candidate for development of a national Maximum Contaminant Level (MCL) standard in drinking water. As of 2020 EPA has not announced whether it will develop an MCL. EPA uses toxicity data in developing MCLs for public water systems.
California established a state-level MCL for MTBE in 2000. | 2 | Environmental Chemistry |
Understanding the interfacial energy of materials with different types of interphase boundaries (IPBs) provides valuable insights into several aspects of their behavior, including thermodynamic stability, deformation behavior, and phase evolution. | 8 | Metallurgy |
# Substrate for deubiquitinylating enzyme activity assays.
# Identification/confirmation of enzyme deubiquitinylation activity.
# Investigation of deconjugating enzyme substrate specificity in comparison with alternative UBL-AMC substrates (e.g. NEDD8-AMC) | 1 | Biochemistry |
Large temperature gradients exist in the electrofusion joint during the fusion cycle. The low thermal conductivity of polymers is the main cause of these large gradients. Recent efforts to model the thermal history at various locations using finite element modeling have been successful. | 7 | Physical Chemistry |
AFPs create a difference between the melting point and freezing point (busting temperature of AFP bound ice crystal) known as thermal hysteresis. The addition of AFPs at the interface between solid ice and liquid water inhibits the thermodynamically favored growth of the ice crystal. Ice growth is kinetically inhibited by the AFPs covering the water-accessible surfaces of ice.
Thermal hysteresis is easily measured in the lab with a nanolitre osmometer. Organisms differ in their values of thermal hysteresis. The maximum level of thermal hysteresis shown by fish AFP is approximately −3.5 °C (Sheikh Mahatabuddin et al., SciRep)(29.3 °F). In contrast, aquatic organisms are exposed only to −1 to −2 °C below freezing. During the extreme winter months, the spruce budworm resists freezing at temperatures approaching −30 °C.
The rate of cooling can influence the thermal hysteresis value of AFPs. Rapid cooling can substantially decrease the nonequilibrium freezing point, and hence the thermal hysteresis value. Consequently, organisms cannot necessarily adapt to their subzero environment if the temperature drops abruptly. | 1 | Biochemistry |
In the 1980s, the company began piping wastewater up to 14 miles to evaporation ponds on or near Ivanpah Dry Lake, east of Interstate 15 near Nevada. This pipeline repeatedly ruptured during cleaning operations to remove mineral deposits called scale. The scale is radioactive because of the presence of thorium and radium, which occur naturally in the rare-earth ore. A federal investigation later found that some 60 spills—some unreported—occurred between 1984 and 1998, when the pipeline and chemical processing at the mine were shut down. In all, about 600,000 gallons of radioactive and other hazardous waste flowed onto the desert floor, according to federal authorities. By the end of the 1990s, Unocal was served with a cleanup order and a San Bernardino County district attorney's lawsuit. The company paid more than $1.4 million in fines and settlements. After preparing a cleanup plan and completing an extensive environmental study, Unocal in 2004 won approval of a county permit that allowed the mine to operate for another 30 years. The mine passed a key county inspection in 2007. | 8 | Metallurgy |
For GPCRs generally, each mechanism of homologous desensitization begins with receptor phosphorylation by an associated G protein-coupled receptor kinase (GRK). GRKs selectively modify activated receptors such that no heterogeneous desensitization will occur. This phosphorylation then acts to recruit other proteins, such as arrestins, that participate in one or more of the following mechanisms. | 1 | Biochemistry |
In organic chemistry, a carbyne is a general term for any compound whose structure consists of an electrically neutral carbon atom connected by a single covalent bond and has three non-bonded electrons. The carbon atom has either one or three unpaired electrons, depending on its excitation state; making it a radical. The chemical formula can be written or (also written as ), or just CH.
Carbynes can be seen as derivatives of the simplest such compound, the methylidyne radical or unsubstituted carbyne or , in which the functional group is a hydrogen atom.
Reported for the first time back in 1967 by Kasatochkin, carbyne is an infinite sp1 hybridized long linear chain of carbon, where each link is just a single carbon atom. | 0 | Organic Chemistry |
Imine hydrogenation provides a practical route to chiral amines.
Metolachlor is the active ingredient in the widely used herbicide Dual Magnum. A key step in its industrial production involves the enantioselective reduction of an N-aryl imine. This reduction is achieved with extremely high turnover number (albeit moderate enantioselectivity) through the use of a specialized catalyst system consisting of [Ir(COD)Cl], modified Josiphos ligand 3, and acid and iodide additives. | 0 | Organic Chemistry |
Naomi Chayen is a biochemist and structural biologist. She is a professor of Biomedical Sciences at Imperial College London, where she leads the Crystallization Group in Computational and Systems Medicine. She is best known for developing the microbatch method and inventing novel nucleants for protein crystallization which have been applied to high-throughput screening for rational drug design. | 1 | Biochemistry |
Medical uses include:
* High blood pressure
* Congestive heart failure
* Following heart attack in people with evidence of heart failure
* People over 55 years at high risk: prevention of heart attack, stroke, cardiovascular death, or in need of revascularization procedures
* Prevent the onset and/or delay the progression of diabetic kidney disease, with or without proteinuria. Randomized trial evidence suggests that a maximum tolerable dose prevents cardiovascular events and death in patients with diabetic kidney disease. | 4 | Stereochemistry |
In photo reduction the promoted electron of the metal oxide is accepted by an acceptor species. In the case of CO reduction, shown in the table below, the absence of dissolved oxygen in the aqueous system favors reduction of protons to form hydrogen radicals which then go on to reduce CO to HCOOH. HCOOH can then be further reduced to HCOH and water. Further reduction leads to the production of CH that can combine in a number of ways to produce CH or CH, etc. | 7 | Physical Chemistry |
Yttrium is a chemical element; it has symbol Y and atomic number 39. It is a silvery-metallic transition metal chemically similar to the lanthanides and has often been classified as a "rare-earth element". Yttrium is almost always found in combination with lanthanide elements in rare-earth minerals and is never found in nature as a free element. Y is the only stable isotope and the only isotope found in the Earth's crust.
The most important present-day use of yttrium is as a component of phosphors, especially those used in LEDs. Historically, it was once widely used in the red phosphors in television set cathode ray tube displays. Yttrium is also used in the production of electrodes, electrolytes, electronic filters, lasers, superconductors, various medical applications, and tracing various materials to enhance their properties.
Yttrium has no known biological role. Exposure to yttrium compounds can cause lung disease in humans. | 8 | Metallurgy |
Like other β-lactam antibiotics, dicloxacillin acts by inhibiting the synthesis of bacterial cell walls. It inhibits cross-linkage between the linear peptidoglycan polymer chains that make up a major component of the cell wall of Gram-positive bacteria. | 4 | Stereochemistry |
The majority of synthetic ion channels follow an Eisenman I sequence (Cs > Rb > K > Na >> Li) in their selectivity for alkali metal cations, suggesting that the origin of the selectivity is governed by the difference in energy required to remove water from a fully hydrated cation. A few synthetic channels show other patterns of ion selectivity, and only a single instance in which a synthetic channel following the opposite selectivity sequence (Eisenman XI; Cs ) had been reported. | 6 | Supramolecular Chemistry |
Preoperative administration of Lugols solution decreases intraoperative blood loss during thyroidectomy in patients with Graves disease. However, it appears ineffective in patients who are already euthyroid on anti-thyroid drugs and levothyroxine.
* During colposcopy, Lugols iodine is applied to the vagina and cervix. Normal vaginal tissue stains brown due to its high glycogen content, while tissue suspicious for cancer does not stain, and thus appears pale compared to the surrounding tissue. Biopsy of suspicious tissue can then be performed. This is called a Schillers test.
* Patients at high risk of oesophageal squamous cell carcinoma are usually followed using a combination of Lugol’s chromoendoscopy and narrow-band imaging. With Lugol’s iodine, low-grade dysplasia appears as an unstained or weakly stained area; high-grade dysplasia is consistently unstained.
* Lugol's iodine may also be used to better visualize the mucogingival junction in the mouth. Similar to the method of staining mentioned above regarding a colposcopy, alveolar mucosa has a high glycogen content that gives a positive iodine reaction vs. the keratinized gingiva.
* Lugol's iodine may also be used as an oxidizing germicide, however it is somewhat undesirable in that it may lead to scarring and discolors the skin temporarily. One way to avoid this problem is by using a solution of 70% ethanol to wash off the iodine later.
* Lugols iodine was distributed in Polish Peoples Republic after the Chernobyl catastrophe, due to government not being informed of how severe the event was and overestimating radiation, and unavailability of iodine tablets. | 3 | Analytical Chemistry |
Water continuous (oil-in-water) emulsified fuels are exemplified by the Orimulsion system and bitumen emulsions. These are often described as a high internal phase emulsion (HIPE) because the continuous phase is around 30% of the composition of the fuel, whereas it is more usual for the dispersed phase to be the minor component. Water continuous emulsions of very heavy crudes, bitumen are easier to pump than the original fuel, which would require considerable heating and / or dilution with a distilled product (kerosene or light crude) in order to make them easy to handle. Water continuous emulsions of residual fuel, heavy fuel oils etc. which have a calorific value and are used in industrial applications can also be converted to emulsified fuels, thus reducing the need to use cutter fluids and improving the combustion emissions associated with the inferior fuels.
Oil continuous (water-in-oil) emulsified fuels are exemplified by diesel (or biodiesel blended fuels) and water emulsions. These emulsified fuels were recognized in Europe (France and Italy) and CEN workshop standard was established (CWA 15145:2004). Other types of fuels have been emulsified contain between 5 and 30% water (by mass) in the overall fuel emulsion. Water-in-diesel fuel emulsion could be used as an alternative fuel for low emissions and high brake thermal efficiency.
Emulsion to combustion (E2C) or on-demand water-in-fuel emulsions for HFO and Diesel for shipping and stationary boilers are available from Nonox Ltd. since 2006. The advantage of mixing on demand is no chemical surfactants are required, water/fuel ratio can be adjusted to load for maximum efficiency and no chance of separation in storage. This proven system reduces soot emissions up to 90%, NOx 40% and offers fuel savings which vary depending on the baseline efficiency of the load.
Microemulsions of fuels have also been prepared. The type of surfactants and quantities required to make these emulsion fuels sets them apart from other commercial emulsion fuels. These are considered where safety issues (e.g. fire prevention;) or commercial return justify the extra costs (e.g. enhance oil recovery, surfactant flooding;). | 7 | Physical Chemistry |
In electrochemistry, the Randles–Ševčík equation describes the effect of scan rate on the peak current for a cyclic voltammetry experiment. For simple redox events such as the ferrocene/ferrocenium couple, depends not only on the concentration and diffusional properties of the electroactive species but also on scan rate.
Or if the solution is at 25 °C:
* = current maximum in amps
* = number of electrons transferred in the redox event (usually 1)
* = electrode area in cm
* = Faraday constant in C mol
* = diffusion coefficient in cm/s
* = concentration in mol/cm
* = scan rate in V/s
* = Gas constant in J K mol
* = temperature in K
* The constant with a value of 2.69x10 has units of C mol V
For novices in electrochemistry, the predictions of this equation appear counter-intuitive, i.e. that increases at faster voltage scan rates. It is important to remember that current, i, is charge (or electrons passed) per unit time. In cyclic voltammetry, the current passing through the electrode is limited by the diffusion of species to the electrode surface. This diffusion flux is influenced by the concentration gradient near the electrode. The concentration gradient, in turn, is affected by the concentration of species at the electrode, and how fast the species can diffuse through solution. By changing the cell voltage, the concentration of the species at the electrode surface is also changed, as set by the Nernst equation. Therefore, a faster voltage sweep causes a larger concentration gradient near the electrode, resulting in a higher current. | 3 | Analytical Chemistry |
The PI3K pathway is a major source of drug resistance in prostate cancer. This is particularly true in castration-resistant prostate cancer, where tumours become resistant to androgen-deprivation therapy, which block the tumours ability to utilise the hormone androgen to grow. This is due to a complex feedback mechanism which exists between the androgen receptor and the PI3K pathway. As in other tumour types, mutations in key genes of this pathway can lead to hyperactivation of this pathway, for example in PIK3CA, Increases in the copy number of PIK3CA and increased mRNA expression also increases pathway activation in prostate cancers among others. Gains in the nearby genetic region 3q26.31-32 have been shown to co-occur with a number of nearby PI3K family members including PIK3CA, PIK3CB and PIK3R4, leading to transcriptional changes in PIK3C2G, PIK3CA, PIK3CB, PIK3R4 as well as pathways associated with cell proliferation. These large spanning gains associate with Gleason grade, tumour stage, lymph node metastasis and other aggressive clinical features. In patients treated with PI3K inhibitors, those with copy number gains in PIK3CB appear to have increased drug susceptibility. | 1 | Biochemistry |
Volume Bragg gratings (VBG) or volume holographic gratings (VHG) consist of a volume where there is a periodic change in the refractive index. Depending on the orientation of the refractive index modulation, VBG can be used either to transmit or reflect a small bandwidth of wavelengths. Bragg's law (adapted for volume hologram) dictates which wavelength will be diffracted:
where is the Bragg order (a positive integer), the diffracted wavelength, Λ the fringe spacing of the grating, the angle between the incident beam and the normal () of the entrance surface and the angle between the normal and the grating vector (). Radiation that does not match Bragg's law will pass through the VBG undiffracted. The output wavelength can be tuned over a few hundred nanometers by changing the incident angle (). VBG are being used to produce widely tunable laser source or perform global hyperspectral imagery (see Photon etc.). | 3 | Analytical Chemistry |
Ring-opening polymerization that involves β-alkyl elimination can be catalyzed by Ti, Zr, Pd-based catalyst, and some Lanthanide-based metallocene catalyst, where different polymerization patterns vary when catalysts are different. Examples of copolymerization with alkene or carbon monoxide were also reported. The key step of this kind of ROP is string-driven β-alkyl elimination, which provides linear polymer with unsaturation in the polymer chain. | 0 | Organic Chemistry |
The museum is also home to a large number of old tractors. Two D8 Caterpillars, a D9, a few large 1930s Caterpillars, some Best crawlers and many other examples of tracked tractors can be seen at the museum. The typical tractors such as Farmall, John Deere, Oliver, and Allis-Chalmers can be seen out at the museum, but there are more than a few rarer examples too. There is a 1924 Buffalo-Springfield road roller, a gigantic 1918 30-60 Aultman-Taylor gas tractor, a 1911 Fairbanks-Morse 15-25 kerosene tractor, a 1915 International Harvester Mogul 8-16, several Rumely Oil-Pulls, and many more. | 8 | Metallurgy |
Most transcription factors function in cooperation with other factors by protein–protein interactions. Association of MITF with other proteins is a critical step in the regulation of MITF-mediated transcriptional activity. Some commonly studied MITF interactions include those with MAZR, PIAS3, Tfe3, hUBC9, PKC1, and LEF1. Looking at the variety of structures gives insight into MITF's varied roles in the cell.
The Myc-associated zinc-finger protein related factor (MAZR) interacts with the Zip domain of MITF. When expressed together, both MAZR and MITF increase promoter activity of the mMCP-6 gene. MAZR and MITF together transactivate the mMCP-6 gene. MAZR also plays a role in the phenotypic expression of mast cells in association with MITF.
PIAS3 is a transcriptional inhibiter that acts by inhibiting STAT3's DNA binding activity. PIAS3 directly interacts with MITF, and STAT3 does not interfere with the interaction between PIAS3 and MITF. PIAS3 functions as a key molecule in suppressing the transcriptional activity of MITF. This is important when considering mast cell and melanocyte development.
MITF, TFE3 and TFEB are part of the basic helix-loop-helix-leucine zipper family of transcription factors. Each protein encoded by the family of transcription factors can bind DNA. MITF is necessary for melanocyte and eye development and new research suggests that TFE3 is also required for osteoclast development, a function redundant of MITF. The combined loss of both genes results in severe osteopetrosis, pointing to an interaction between MITF and other members of its transcription factor family. In turn, TFEB has been termed as the master regulator of lysosome biogenesis and autophagy. Interestingly, MITF, TFEB and TFE3 separate roles in modulating starvation-induced autophagy have been described in melanoma. Moreover, MITF and TFEB proteins, directly regulate each other’s mRNA and protein expression while their subcellular localization and transcriptional activity are subject to similar modulation, such as the mTOR signaling pathway.
UBC9 is a ubiquitin conjugating enzyme whose proteins associates with MITF. Although hUBC9 is known to act preferentially with SENTRIN/SUMO1, an in vitro analysis demonstrated greater actual association with MITF. hUBC9 is a critical regulator of melanocyte differentiation. To do this, it targets MITF for proteasome degradation.
Protein kinase C-interacting protein 1 (PKC1) associates with MITF. Their association is reduced upon cell activation. When this happens MITF disengages from PKC1. PKC1 by itself, found in the cytosol and nucleus, has no known physiological function. It does, however, have the ability to suppress MITF transcriptional activity and can function as an in vivo negative regulator of MITF induced transcriptional activity.
The functional cooperation between MITF and the lymphoid enhancing factor (LEF-1) results in a synergistic transactivation of the dopachrome tautomerase gene promoter, which is an early melanoblast marker. LEF-1 is involved in the process of regulation by Wnt signaling. LEF-1 also cooperates with MITF-related proteins like TFE3. MITF is a modulator of LEF-1, and this regulation ensures efficient propagation of Wnt signals in many cells. | 1 | Biochemistry |
Chemokine-like factor (CKLF) is a member of the CKLF-like MARVEL transmembrane domain-containing family of proteins that in humans is encoded by the CKLF gene. This gene is located on band 22.1 in the long (i.e. "q") arm of chromosome 16. | 1 | Biochemistry |
An electrophoretic mobility shift assay (EMSA) or mobility shift electrophoresis, also referred as a gel shift assay, gel mobility shift assay, band shift assay, or gel retardation assay, is a common affinity electrophoresis technique used to study protein–DNA or protein–RNA interactions. This procedure can determine if a protein or mixture of proteins is capable of binding to a given DNA or RNA sequence, and can sometimes indicate if more than one protein molecule is involved in the binding complex. Gel shift assays are often performed in vitro concurrently with DNase footprinting, primer extension, and promoter-probe experiments when studying transcription initiation, DNA gang replication, DNA repair or RNA processing and maturation, as well as pre-mRNA splicing. Although precursors can be found in earlier literature, most current assays are based on methods described by Garner and Revzin and Fried and Crothers. | 1 | Biochemistry |
Lipid droplets bud off the membrane of the endoplasmic reticulum. Initially, a lens is formed by accumulation of TAGs between the two layers of its phospholipid membrane. Nascent lipid droplets may grow by diffusion of fatty acids, endocytosis of sterols, or fusion of smaller lipid droplets through the aid of SNARE proteins. The budding of lipid droplets is promoted by an asymmetric accumulation of phospholipids that decrease surface tension towards the cytosol. Lipid droplets have also been observed to be created by the fission of existing lipid droplets, though this is thought to be less common than de novo formation.
The formation of lipid droplets from the endoplasmic reticulum begins with the synthesis of the neutral lipids to be transported. The manufacture of TAGs from diacylglycerol (by the addition of a fatty acyl chain) is catalyzed by the DGAT proteins, though the extent to which these and other proteins are required depends on cell type. Neither DGAT1 nor DGAT2 is singularly essential for TAG synthesis or droplet formation, though mammalian cells lacking both cannot form lipid droplets and have severely stunted TAG synthesis. DGAT1, which seems to prefer exogenous fatty acid substrates, is not essential for life; DGAT2, which seems to prefer endogenously synthesized fatty acids, is.
In non-adipocytes, lipid storage, lipid droplet synthesis and lipid droplet growth can be induced by various stimuli including growth factors, long-chain unsaturated fatty acids (including oleic acid and arachidonic acid), oxidative stress and inflammatory stimuli such bacterial lipopolysaccharides, various microbial pathogens, platelet-activating factor, eicosanoids, and cytokines.
An example is the endocannabinoids that are unsaturated fatty acid derivatives, which mainly are considered to be synthesised “on demand” from phospholipid precursors residing in the cell membrane, but may also be synthesised and stored in intracellular lipid droplets and released from those stores under appropriate conditions.
It is possible to observe the formation of lipid droplets, live and label-free, using label-free live-cell imaging. | 1 | Biochemistry |
The Grieco three-component condensation is an organic chemistry reaction that produces nitrogen-containing six-member heterocycles via a multi-component reaction of an aldehyde, a nitrogen component, such as aniline, and an electron-rich alkene. The reaction is catalyzed by trifluoroacetic acid or Lewis acids such as ytterbium trifluoromethanesulfonate (Yb(OTf)). The reaction is named for Paul Grieco, who first reported it in 1985. In the original paper the nitrogen component were benzylamine, methyl amine or ammonium chloride, the reaction now also include anilines, similar to the earlier Povarov reaction.
The reaction process involves the formation of an aryl immonium ion intermediate followed by an aza Diels-Alder reaction with an alkene. Imines are electron-poor, and thus usually function as the dienophile. Here, however, the alkene is electron-rich, so it reacts well with the immonium diene in an Inverse electron-demand Diels–Alder reaction.
Researchers have extended the Grieco three-component reaction to reactants or catalysts immobilized on solid support, which greatly expands the application of this reaction to various combinatorial chemistry settings. Kielyov and Armstrong were the first to report a solid-supported version of this reaction, they found that this reaction works well for each reactants immobilized on solid support. Kobayashi and co-workers show that a polymer-supported scandium catalyst catalyze the Grieco reaction with high efficiency.
Given the effectiveness of the reaction and the commercial availability of various Grieco partners, the Grieco three-component coupling is very useful for preparing quinoline libraries for drug discovery. | 0 | Organic Chemistry |
Chloroplasts are one of many types of organelles in the plant cell. They are considered to have evolved from endosymbiotic cyanobacteria. Mitochondria are thought to have come from a similar endosymbiosis event, where an aerobic prokaryote was engulfed. This origin of chloroplasts was first suggested by the Russian biologist Konstantin Mereschkowski in 1905 after Andreas Franz Wilhelm Schimper observed in 1883 that chloroplasts closely resemble cyanobacteria. Chloroplasts are only found in plants, algae, and three species of amoeba – Paulinella chromatophora, P. micropora, and marine P. longichromatophora. | 5 | Photochemistry |
Although histones are remarkably conserved throughout evolution, several variant forms have been identified. This diversification of histone function is restricted to H2A and H3, with H2B and H4 being mostly invariant. H2A can be replaced by H2AZ (which leads to reduced nucleosome stability) or H2AX (which is associated with DNA repair and T cell differentiation), whereas the inactive X chromosomes in mammals are enriched in macroH2A. H3 can be replaced by H3.3 (which correlates with activate genes and regulatory elements) and in centromeres H3 is replaced by CENPA. | 1 | Biochemistry |
On September 11, 2007, Sepracor signed a marketing deal with British pharmaceutical company GlaxoSmithKline for the rights to sell eszopiclone (under the name Lunivia rather than Lunesta) in Europe. Sepracor was expected to receive approximately $155 million if the deal went through. In 2008 Sepracor submitted an application to the EMA (the European Unions equivalent to the U.S. FDA) for authorization to market the drug in the EU, and initially received a favorable response. However, Sepracor withdrew its authorization application in 2009 after the EMA stated it would not be granting eszopiclone new active substance status, as it was essentially pharmacologically and therapeutically too similar to zopiclone to be considered a new patentable product. Since the patent on zopiclone has expired, this ruling would have allowed rival companies to also legally produce cheaper generic versions of eszopiclone for the European market. , Sepracor has not resubmitted its authorization application and eszopiclone is not available in Europe. The deal with GSK fell through, and GSK instead launched a $3.3 billion deal to market Actelions almorexant sleeping tablet, which entered phase 3 medical trials before development was abandoned due to side effects. | 4 | Stereochemistry |
A chromatin variant corresponds to a section of the genome that differs in chromatin states across cell types/states within an individual (intra-individual) or between individuals for a given cell type/state (inter-individual). Chromatin variants distinguish DNA sequences that differ in their function in one cell type/state versus another. Chromatin variants are found across the genome, inclusive of repetitive and non-repetitive DNA sequence. Chromatin variants range in sizes. The smallest chromatin variants cover a few hundred DNA base pairs, such as seen at promoters, enhancers or insulators. The largest chromatin variants capture a few thousand DNA base pairs, such as seen at Large Organized Chromatin Lysine domains (LOCKs) and Clusters Of Cis-Regulatory Elements (COREs), such as super-enhancer. | 1 | Biochemistry |
RPB3 is involved in RNA polymerase II assembly. A subcomplex of RPB2 and RPB3 appears soon after subunit synthesis. This complex subsequently interacts with RPB1. RPB3, RPB5, and RPB7 interact with themselves to form homodimers, and RPB3 and RPB5 together are able to contact all of the other RPB subunits, except RPB9. Only RPB1 strongly binds to RPB5. The RPB1 subunit also contacts RPB7, RPB10, and more weakly but most efficiently with RPB8. Once RPB1 enters the complex, other subunits such as RPB5 and RPB7 can enter, where RPB5 binds to RPB6 and RPB8 and RPB3 brings in RPB10, RPB 11, and RPB12. RPB4 and RPB9 may enter once most of the complex is assembled. RPB4 forms a complex with RPB7. | 1 | Biochemistry |
The hydrogen ion, or hydronium ion, is a Brønsted–Lowry acid when dissolved in HO and the hydroxide ion is a base because of the self-separating reaction
An analogous reaction occurs in liquid ammonia
Thus, the ammonium ion, , in liquid ammonia corresponds to the hydronium ion in water and the amide ion, in ammonia, to the hydroxide ion in water. Ammonium salts behave as acids, and amides behave as bases.
Some non-aqueous solvents can behave as bases, i.e. accept protons, in relation to Brønsted–Lowry acids.
where S stands for a solvent molecule. The most important of such solvents are dimethylsulfoxide, DMSO, and acetonitrile, , as these solvents have been widely used to measure the acid dissociation constants of carbon-containing molecules. Because DMSO accepts protons more strongly than the acid becomes stronger in this solvent than in water. Indeed, many molecules behave as acids in non-aqueous solutions but not in aqueous solutions. An extreme case occurs with carbon acids, where a proton is extracted from a bond.
Some non-aqueous solvents can behave as acids. An acidic solvent will make dissolved substances more basic. For example, the compound is known as acetic acid since it behaves as an acid in water. However it behaves as a base in liquid hydrogen chloride, a much more acidic solvent. | 7 | Physical Chemistry |
MP Materials is 51.8%-owned by US hedge funds JHL Capital Group (and its CEO James Litinsky) and QVT Financial LP, while Shenghe Resources Holding Co. Ltd., a partially state-owned enterprise of the Government of China, holds an 8.0% stake. Apart from institutions, the public owns 18%. | 8 | Metallurgy |
This area of study has recently gained more importance due to the increasing evidence that post-transcriptional regulation plays a larger role than previously expected. Even though protein with DNA binding domains are more abundant than protein with RNA binding domains, a recent study by Cheadle et al. (2005) showed that during T-cell activation 55% of significant changes at the steady-state level had no corresponding changes at the transcriptional level, meaning they were a result of stability regulation alone.
Furthermore, RNA found in the nucleus is more complex than that found in the cytoplasm: more than 95% (bases) of the RNA synthesized by RNA polymerase II never reaches the cytoplasm. The main reason for this is due to the removal of introns which account for 80% of the total bases. Some studies have shown that even after processing the levels of mRNA between the cytoplasm and the nucleus differ greatly.
Developmental biology is a good source of models of regulation, but due to the technical difficulties it was easier to determine the transcription factor cascades than regulation at the RNA level. In fact several key genes such as nanos are known to bind RNA but often their targets are unknown. Although RNA binding proteins may regulate post transcriptionally large amount of the transcriptome, the targeting of a single gene is of interest to the scientific community for medical reasons, this is RNA interference and microRNAs which are both examples of posttranscriptional regulation, which regulate the destruction of RNA and change the chromatin structure. To study post-transcriptional regulation several techniques are used, such as RIP-Chip (RNA immunoprecipitation on chip). | 1 | Biochemistry |
In deep mutational scanning every possible amino acid change in a given protein is first synthesized. The activity of each of these protein variants is assayed in parallel using barcodes for each variant. By comparing the activity to the wild-type protein, the effect of each mutation is identified. While it is possible to assay every possible single amino-acid change due to combinatorics two or more concurrent mutations are hard to test. Deep mutational scanning experiments have also been used to infer protein structure and protein-protein interactions | 1 | Biochemistry |
Stress corrosion cracking (SCC) is the growth of a crack in a corrosive environment. It requires three conditions to take place: 1)corrosive environment 2)stress 3)susceptible material. SCC can lead to unexpected sudden and hence catastrophic failure of normally ductile metals under tensile stress. This is usually exacerbated at elevated temperature. SCC is highly chemically specific in that certain alloys are likely to undergo SCC only when exposed to a small number of chemical environments. It is common for SCC to go undetected prior to failure. SCC usually quite progresses rapidly after initial crack initiation, and is seen more often in alloys as opposed to pure metals. The corrosion engineer thus must be aware of this phenomenon. | 8 | Metallurgy |
Conditional mutations can be produced in mice which affect only specific cells or tissues at specific times, so that the mouse can develop to adulthood and the adult phenotype can be studied. In one case, MED1 was found to participate in controlling the timing of events of meiosis in male mice. Conditional mutants in keratinocytes show differences in skin wound healing. A conditional mutant in mice was found to change dental epithelium into epidermal epithelium, which caused hair to grow associated with the incisors. | 1 | Biochemistry |
Simultaneous measurement of and for 1:1 adducts is routinely carried out using isothermal titration calorimetry. Extension to more complex systems is limited by the availability of suitable software. | 7 | Physical Chemistry |
At and below, pure tin transforms from the silvery, ductile metallic allotrope of β-form white tin to the brittle, nonmetallic, α-form grey tin with a diamond cubic structure. The transformation is slow to initiate due to a high activation energy but the presence of germanium (or crystal structures of similar form and size) or very low temperatures of roughly −30 °C aids the initiation. There is also a large volume increase of about 27% associated with the phase change to the nonmetallic low temperature allotrope. This frequently makes tin objects (like buttons) decompose into powder during the transformation, hence the name tin pest. The decomposition will catalyze itself, which is why the reaction accelerates once it starts. The mere presence of tin pest leads to tin pest. Tin objects at low temperatures will simply disintegrate. | 8 | Metallurgy |
AGEs are the subject of ongoing research. There are three therapeutic approaches: preventing the formation of AGEs, breaking crosslinks after they are formed and preventing their negative effects.
Compounds that have been found to inhibit AGE formation in the laboratory include Vitamin C, Agmatine, benfotiamine, pyridoxamine, alpha-lipoic acid, taurine, pimagedine, aspirin, carnosine, metformin, pioglitazone, and pentoxifylline. Activation of the TRPA-1 receptor by lipoic acid or podocarpic acid has been shown to reduce the levels of AGES by enhancing the detoxification of methylglyoxal, a major precursor of several AGEs.
Studies in rats and mice have found that natural phenols such as resveratrol and curcumin can prevent the negative effects of the AGEs.
Compounds that are thought to break some existing AGE crosslinks include Alagebrium (and related ALT-462, ALT-486, and ALT-946) and N-phenacyl thiazolium bromide. One in vitro study shows that rosmarinic acid out performs the AGE breaking potential of ALT-711.
There is, however, no agent known that can break down the most common AGE, glucosepane, which appears 10 to 1,000 times more common in human tissue than any other cross-linking AGE.
Some chemicals, on the other hand, like aminoguanidine, might limit the formation of AGEs by reacting with 3-deoxyglucosone. | 1 | Biochemistry |
With few exceptions, most chloroplasts have their entire chloroplast genome combined into a single large circular DNA molecule, typically 120,000–170,000 base pairs long. They can have a contour length of around 30–60 micrometers, and have a mass of about 80–130 million daltons.
While usually thought of as a circular molecule, there is some evidence that chloroplast DNA molecules more often take on a linear shape. | 5 | Photochemistry |
There are several models used to predict liquidus and solidus curves for various systems.
Detailed measurements of solidus and liquidus can be made using techniques such as differential scanning calorimetry and differential thermal analysis. | 7 | Physical Chemistry |
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