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Single molecule fluorescent sequencing is one method of DNA sequencing. The core principle is the imaging of individual fluorophore molecules, each corresponding to one base. By working on single molecule level, amplification of DNA is not required, avoiding amplification bias. The method lends itself to parallelization by probing many sequences simultaneously, imaging all of them at the same time.
The principle can be applied stepwise (e.g. the Helicos implementation), or in real time (as in the Pacific Biosciences implementation). | 1 | Applied and Interdisciplinary Chemistry |
Mitochondrial replacement therapy has been used to prevent the transmission of mitochondrial diseases from mother to child; it could only be performed in clinics licensed by the UK's Human Fertilisation and Embryology Authority (HFEA), only for people individually approved by the HFEA, for whom preimplantation genetic diagnosis is unlikely to be helpful, and only with informed consent that the risks and benefits are not well understood.
Relevant mutations are found in about 0.5% of the population and disease affects around one in 5000 individuals (0.02%)—the percentage of people affected is much smaller because cells contain many mitochondria, only some of which carry mutations, and the number of mutated mitochondria need to reach a threshold in order to affect the entire cell, and many cells need to be affected for the person to show disease.
The average number of births per year among women at risk for transmitting mtDNA disease is estimated to approximately 150 in the United Kingdom and 800 in the United States.
Prior to the development of MRT, and in places where it is not legal or feasible, the reproductive options for women who are at risk for transmitting mtDNA disease and who want to prevent transmission were using an egg from another woman, adoption, or childlessness. | 1 | Applied and Interdisciplinary Chemistry |
Source:
Falkner and Skan generalized the Blasius boundary layer by considering a wedge with an angle of from some uniform velocity field . Falkner and Skans first key assumption was that the pressure gradient term in the Prandtl x'-momentum equation could be replaced by the differential form of the Bernoulli equation in the high Reynolds number limit. Thus:
Here is the velocity of at the boundary layer edge and is the solution the Euler equations (fluid dynamics) in the outer region.
Having made the Bernoulli equation substitution, Falkner and Skan pointed out that similarity solutions are obtained when the boundary layer thickness and velocity scaling factors are assumed to be simple power functions of x. That is, they assumed the velocity similarity scaling factor is given by:
where is the wedge length and m is a dimensionless constant. Falkner and Skan also assumed the boundary layer thickness scaling factor is porpotional to:
Mass conservation is automatically ensured when the Prandtl momentum boundary layer equations are solved using a stream function approach. The stream function, in terms of the scaling factors, is given by:
where and the velocities are given by:
This means
The non-dimensionalized Prandtl x-momentum equation using the similarity length and velocity scaling factors together with the stream function based velocities results in an equation known as the Falkner–Skan equation and is given by:
where each dash represents differentiation with respect to (Note that another equivalent equation with a different involving an is sometimes used. This changes f and its derivatives but ultimately results in the same backed-out and solutions). This equation can be solved for certain as an ODE with boundary conditions:
The wedge angle, after some manipulation, is given by:
The case corresponds to the Blasius boundary layer solution. When , the problem reduces to the Hiemenz flow. Here, m . For more negative values of m, that is, for stronger adverse pressure gradients, all solutions satisfying the boundary conditions at η = 0 have the property that f(η) > 1 for a range of values of η. This is physically unacceptable because it implies that the velocity in the boundary layer is greater than in the main flow. Further details may be found in Wilcox (2007).
With the solution for f and its derivatives in hand, the Falkner and Skan velocities become:
and
The Prandtl -momentum equation can be rearranged to obtain the -pressure gradient, /, (this is the formula appropriate for the =1 and =2m/(m+1) case) as
where the displacement thickness, , for the Falkner-Skan profile is given by:
and the shear stress acting at the wedge is given by | 1 | Applied and Interdisciplinary Chemistry |
A primary example of lithotrophs that contribute to soil formation is Cyanobacteria. This group of bacteria are nitrogen-fixing photolithotrophs that are capable of using energy from sunlight and inorganic nutrients from rocks as reductants. This capability allows for their growth and development on native, oligotrophic rocks and aids in the subsequent deposition of their organic matter (nutrients) for other organisms to colonize. Colonization can initiate the process of organic compound decomposition: a primary factor for soil genesis. Such a mechanism has been attributed as part of the early evolutionary processes that helped shape the biological Earth. | 1 | Applied and Interdisciplinary Chemistry |
A sequence space is usually laid out as a grid. For protein sequence spaces, each residue in the protein is represented by a dimension with 20 possible positions along that axis corresponding to the possible amino acids. Hence there are 400 possible dipeptides arranged in a 20x20 space but that expands to 10 for even a small protein of 100 amino acids arranged in a space with 100 dimensions. Although such overwhelming multidimensionality cannot be visualised or represented diagrammatically, it provides a useful abstract model to think about the range of proteins and evolution from one sequence to another.
These highly multidimensional spaces can be compressed to 2 or 3 dimensions using principal component analysis. A fitness landscape is simply a sequence space with an extra vertical axis of fitness added for each sequence. | 1 | Applied and Interdisciplinary Chemistry |
The second stage is the oxidation of the carbon in the remaining sample in the form of carbon dioxide (CO) and other gases. Modern TOC analyzers perform this oxidation step by several processes:
* High temperature combustion
* High temperature catalytic oxidation (HTCO)
* Photo-oxidation alone
* Thermo-chemical oxidation
* Photo-chemical oxidation
* Electrolytic oxidation | 0 | Theoretical and Fundamental Chemistry |
Müller as the Austrian chief surveyor of mines in Transylvania was responsible for the analysis of ore samples. He analyzed gold ore from Kleinschlatten (today Zlatna, Romania). This ore was known as "Faczebajer weißes blättriges Golderz" (white leafy gold ore from Faczebaja) or antimonalischer Goldkies (antimonic gold pyrite), and, according to Anton von Rupprecht, was Spießglaskönig (argent molybdique), containing native antimony. Müller concluded that the ore did not contain antimony, but that it was bismuth sulfide. The following year, he reported that this was erroneous and that the ore contained mostly gold and an unknown metal very similar to antimony. After a thorough investigation which lasted for three years and consisted of more than fifty tests, Müller determined the specific gravity of the mineral and noted the radish-like odor of the white smoke which passed off when the new metal was heated, the red color which the metal imparts to sulfuric acid, and the black precipitate which this solution gives when diluted with water. Nevertheless, he was not able to identify this metal and gave it the names and , as it did not show the properties predicted for the expected antimony.
In 1798, the German chemist Martin Heinrich Klaproth isolated the new element from a sample sent by Müller. After a thorough examination of the material he concluded that a new metal was present in the sample. He called it tellurium, but gave the credit of the discovery to Müller. | 1 | Applied and Interdisciplinary Chemistry |
The genomic basis of the Crabtree effect is still being investigated, and its evolution likely involved multiple successive molecular steps that increased the efficiency of the lifestyle. | 1 | Applied and Interdisciplinary Chemistry |
The isomerization of uridine to pseudoridine is the second most common rRNA modification. These pseudoridines are also introduced by the same classes of snoRNPs that participate in methylation. Psuedouridine synthases are the major participating enzymes in the reaction. The H/ACA box snoRNPs introduce guide sequences that are about 14-15 nucleotides long. Pseudouridylation is triggered in numerous places of rRNAs at once to preserve the thermal stability of RNA. Pseudouridine allows for increased hydrogen bonding and alters translation in rRNA and tRNA. It alters translation by increasing the affinity of the ribosome subunit to specific mRNAs.
Base Editing:
Base editing is the third major class of rRNA modification, specifically in eukaryotes. There are 8 categories of base edits that can occur at the gap between the small and large ribosomal subunits. RNA methyltransferases are the enzymes that introduce base methylation. Acetyltransferases are the enzymes responsible for acetylation of cytosine in rRNA. Base methylation plays a role in translation. These base modifications all work in conjunction with the two other main classes of modification to contribute to RNA structural stability. An example of this occurs in N7-methylation, which increases the nucleotide's charge to increase ionic interactions of proteins attaching to the RNA before translation. | 1 | Applied and Interdisciplinary Chemistry |
Allyl complexes are often generated by oxidative addition of allylic halides to low-valent metal complexes. This route is used to prepare (allyl)NiCl:
:2 Ni(CO) + 2 ClCHCH=CH → Ni(μ-Cl)(η-CH) + 8 CO
A similar oxidative addition involves the reaction of allyl bromide to diiron nonacarbonyl. Oxidative addition route has been used for Mo(II) allyl complexes as well:
Other methods of synthesis involve addition of nucleophiles to η-diene complexes and hydride abstraction from alkene complexes. For example, palladium(II) chloride attacks alkenes to give first an alkene complex, but then abstracts hydrogen to give a dichlorohydridopalladium alkene complex, and then eliminates hydrogen chloride:
:PdCl + >C=CHCHPd–(η-(>CCHCHPd(H)⚟(>CCHC<) → ClPd⚟(>CCHC<) + HCl
One allyl complex can transfer an allyl ligand to another complex. An anionic metal complex can displace a halide, to give an allyl complex. However, if the metal center is coordinated to 6 or more other ligands, the allyl may end up "trapped" as a σ (η-) ligand. In such circumstances, heating or irradiation can dislocate another ligand to free up space for the alkene-metal bond.
In principle, salt metathesis reactions can adjoin an allyl ligand from an allylmagnesium bromide or related allyl lithium reagent. However, the carbanion salt precursors require careful synthesis, as allyl halides readily undergo Wurtz coupling. Mercury and tin allyl halides appear to avoid this side-reaction. | 0 | Theoretical and Fundamental Chemistry |
Heating a lactone with a base (sodium hydroxide) will hydrolyse the lactone to its parent compound, the straight chained bifunctional compound. Like straight-chained esters, the hydrolysis-condensation reaction of lactones is a reversible reaction, with an equilibrium. However, the equilibrium constant of the hydrolysis reaction of the lactone is lower than that of the straight-chained ester i.e. the products (hydroxyacids) are less favored in the case of the lactones. This is because although the enthalpies of the hydrolysis of esters and lactones are about the same, the entropy of the hydrolysis of lactones is less than the entropy of straight-chained esters. Straight-chained esters give two products upon hydrolysis, making the entropy change more favorable than in the case of lactones which gives only a single product.
Lactones also react with amines to give the ring-opened alcohol and amide. | 0 | Theoretical and Fundamental Chemistry |
It is sometimes possible to convert an inexact differential into an exact one by means of an integrating factor.
The most common example of this in thermodynamics is the definition of entropy:
In this case, is an inexact differential, because its effect on the state of the system can be compensated by .
However, when divided by the absolute temperature and when the exchange occurs at reversible conditions (therefore the subscript), it produces an exact differential: the entropy is also a state function. | 0 | Theoretical and Fundamental Chemistry |
Measuring LDH in fluid aspirated from a pleural effusion (or pericardial effusion) can help in the distinction between exudates (actively secreted fluid, e.g., due to inflammation) or transudates (passively secreted fluid, due to a high hydrostatic pressure or a low oncotic pressure). The usual criterion (included in Light's criteria) is that a ratio of pleural LDH to serum LDH greater than 0.6 or the upper limit of the normal laboratory value for serum LDH indicates an exudate, while a ratio of less indicates a transudate. Different laboratories have different values for the upper limit of serum LDH, but examples include 200 and 300 IU/L. In empyema, the LDH levels, in general, will exceed 1000 IU/L. | 1 | Applied and Interdisciplinary Chemistry |
The Enders SAMP/RAMP hydrazone alkylation begins with the synthesis of the hydrazone from a N,N-dialkylhydrazine and a ketone or aldehyde
The hydrazone is then deprotonated on the α-carbon position by a strong base, such as lithium diisopropylamide (LDA), leading to the formation of a resonance stabilized anion - an azaenolate. This anion is a very good nucleophile and readily attacks electrophiles, such as alkyl halides, to generate alkylated hydrazones with simultaneous creation of a new chiral center at the α-carbon.
The stereochemistry of this reaction is discussed in detail in next section. | 0 | Theoretical and Fundamental Chemistry |
In the human genome, all genes get transcribed into RNA because that's how the molecular gene is defined. (See Gene.) The transcriptome consists of coding regions of mRNA plus non-coding UTRs, introns, non-coding RNAs, and spurious non-functional transcripts.
Several factors render the content of the transcriptome difficult to establish. These include alternative splicing, RNA editing and alternative transcription among others. Additionally, transcriptome techniques are capable of capturing transcription occurring in a sample at a specific time point, although the content of the transcriptome can change during differentiation. The main aims of transcriptomics are the following: "catalogue all species of transcript, including mRNAs, non-coding RNAs and small RNAs; to determine the transcriptional structure of genes, in terms of their start sites, 5′ and 3′ ends, splicing patterns and other post-transcriptional modifications; and to quantify the changing expression levels of each transcript during development and under different conditions".
The term can be applied to the total set of transcripts in a given organism, or to the specific subset of transcripts present in a particular cell type. Unlike the genome, which is roughly fixed for a given cell line (excluding mutations), the transcriptome can vary with external environmental conditions. Because it includes all mRNA transcripts in the cell, the transcriptome reflects the genes that are being actively expressed at any given time, with the exception of mRNA degradation phenomena such as transcriptional attenuation. The study of transcriptomics, (which includes expression profiling, splice variant analysis etc.), examines the expression level of RNAs in a given cell population, often focusing on mRNA, but sometimes including others such as tRNAs and sRNAs. | 1 | Applied and Interdisciplinary Chemistry |
Phosphoric acid units can be bonded together in rings (cyclic structures). The simplest such compound is trimetaphosphoric acid or cyclo-triphosphoric acid having the formula . Its structure is shown in the illustration. Since the ends are condensed, its formula has one less (water) than tripolyphosphoric acid.
The general formula of a phosphoric acid is , where n is the number of phosphorus atoms and x is the number of fundamental cycles in the molecule's structure; that is, the minimum number of bonds that would have to be broken to eliminate all cycles.
The limiting case of internal condensation, where all oxygen atoms are shared and there are no hydrogen atoms (x = ) is an anhydride , phosphorus pentoxide . | 0 | Theoretical and Fundamental Chemistry |
When referring to the genotype (the gene) the mnemonic is italicized and not capitalised. When referring to the gene product or phenotype, the mnemonic is first-letter capitalised and not italicized (e.g. DnaA – the protein produced by the dnaA gene; LeuA – the phenotype of a leuA mutant; Amp – the ampicillin-resistance phenotype of the β-lactamase gene bla). | 1 | Applied and Interdisciplinary Chemistry |
A number of chelators of divalent cations have different fluorescence spectra in the bound and unbound states. Chelators for Ca are well established, have high affinity for the cation, and low interference from other ions. Mg chelators lag behind and the major fluorescence dye for Mg (mag-fura 2) actually has a higher affinity for Ca. This limits the application of this dye to cell types where the resting level of Ca is is to be measured. Recently, Otten et al. (2001) have described work into a new class of compounds that may prove more useful, having significantly better binding affinities for Mg. The use of the fluorescent dyes is limited to measuring the free Mg. If the ion concentration is buffered by the cell by chelation or removal to subcellular compartments, the measured rate of uptake will give only minimum values of km and Vmax. | 1 | Applied and Interdisciplinary Chemistry |
Transcription produces a single-stranded RNA molecule known as messenger RNA, whose nucleotide sequence is complementary to the DNA from which it was transcribed. The mRNA acts as an intermediate between the DNA gene and its final protein product. The genes DNA is used as a template to generate a complementary mRNA. The mRNA matches the sequence of the genes DNA coding strand because it is synthesised as the complement of the template strand. Transcription is performed by an enzyme called an RNA polymerase, which reads the template strand in the 3 to 5 direction and synthesizes the RNA from 5 to 3. To initiate transcription, the polymerase first recognizes and binds a promoter region of the gene. Thus, a major mechanism of gene regulation is the blocking or sequestering the promoter region, either by tight binding by repressor molecules that physically block the polymerase or by organizing the DNA so that the promoter region is not accessible.
In prokaryotes, transcription occurs in the cytoplasm; for very long transcripts, translation may begin at the 5 end of the RNA while the 3 end is still being transcribed. In eukaryotes, transcription occurs in the nucleus, where the cell's DNA is stored. The RNA molecule produced by the polymerase is known as the primary transcript and undergoes post-transcriptional modifications before being exported to the cytoplasm for translation. One of the modifications performed is the splicing of introns which are sequences in the transcribed region that do not encode a protein. Alternative splicing mechanisms can result in mature transcripts from the same gene having different sequences and thus coding for different proteins. This is a major form of regulation in eukaryotic cells and also occurs in some prokaryotes. | 1 | Applied and Interdisciplinary Chemistry |
Milton M. Conger in 1881 patented and supposedly built a motor that ran off compressed air or steam that using a flexible tubing which will form a wedge-shaped or inclined wall or abutment in the rear of the tangential bearing of the wheel, and propel it with greater or less speed according to the pressure of the propelling medium. | 1 | Applied and Interdisciplinary Chemistry |
McGraw-Hill Dictionary of Scientific & Technical Terms (6. ed.). The McGraw-Hill Companies, Inc. 2003. [http://encyclopedia2.thefreedictionary.com/aquametry] (online May 6, 2011) | 0 | Theoretical and Fundamental Chemistry |
Ionic compounds in the solid state form lattice structures. The two principal factors in determining the form of the lattice are the relative charges of the ions and their relative sizes. Some structures are adopted by a number of compounds; for example, the structure of the rock salt sodium chloride is also adopted by many alkali halides, and binary oxides such as magnesium oxide. Pauling's rules provide guidelines for predicting and rationalizing the crystal structures of ionic crystals | 0 | Theoretical and Fundamental Chemistry |
eIF2B is a protein complex found in eukaryotes. It is the guanine nucleotide exchange factor for the eukaryotic initiation factor 2 and therefore converts the inactive eIF2-GDP to the active eIF2-GTP. This activation is hindered by phosphorylation of the alpha subunit of eIF2, which leads to a stable eIF2α-P-GDP-eIF2B complex and therefore inhibits translation initiation.
Human genes which encode eIF-2B proteins include:
* EIF2B1 – alpha subunit (26kDa)
* EIF2B2 – beta subunit (39kDa)
* EIF2B3 – gamma subunit (58kDa)
* EIF2B4 – delta subunit (67kDa)
* EIF2B5 – epsilon subunit (82kDa) | 1 | Applied and Interdisciplinary Chemistry |
In primary aluminium production, aluminium carbides (AlC) originates from the reduction of alumina where carbon anodes and cathodes are in contact with the mix. Later in the process, any carbon tools in contact with the liquid aluminium can react and create carbides. | 1 | Applied and Interdisciplinary Chemistry |
Triatomic hydrogen will be formed during the neutralization of . This ion will be neutralised in the presence of gasses other than He or H, as it can abstract an electron. Thus H is formed in the aurora in the ionosphere of Jupiter and Saturn. | 0 | Theoretical and Fundamental Chemistry |
The ratio of Fe to Fe within a rock determines, in part, the silicate mineral and oxide mineral assemblage of the rock. Within a rock of a given chemical composition, iron enters minerals based on the bulk chemical composition and the mineral phases which are stable at that temperature and pressure. For instance, at redox conditions more oxidizing than the MH (magnetite-hematite) buffer, at least much of the iron is likely to be present as Fe and hematite is a likely mineral in iron-bearing rocks. Iron may only enter minerals such as olivine if it is present as Fe; Fe cannot enter the lattice of fayalite olivine. Elements in olivine such as magnesium, however, stabilize olivine containing Fe to conditions more oxidizing than those required for fayalite stability. Solid solution between magnetite and the titanium-bearing endmember, ulvospinel, enlarges the stability field of magnetite. Likewise, at conditions more reducing than the IW (iron-wustite) buffer, minerals such as pyroxene can still contain Fe. The redox buffers therefore are only approximate guides to the proportions of Fe and Fe in minerals and rocks. | 0 | Theoretical and Fundamental Chemistry |
Lipofectamine or Lipofectamine 2000 is a common transfection reagent, produced and sold by Invitrogen, used in molecular and cellular biology. It is used to increase the transfection efficiency of RNA (including mRNA and siRNA) or plasmid DNA into in vitro cell cultures by lipofection. Lipofectamine contains lipid subunits that can form liposomes in an aqueous environment, which entrap the transfection payload, e.g. DNA plasmids.
Lipofectamine consists of a 3:1 mixture of DOSPA (2,3‐dioleoyloxy‐N‐ [2(sperminecarboxamido)ethyl]‐N,N‐dimethyl‐1‐propaniminium trifluoroacetate) and DOPE, which complexes with negatively charged nucleic acid molecules to allow them to overcome the electrostatic repulsion of the cell membrane. Lipofectamine's cationic lipid molecules are formulated with a neutral co-lipid (helper lipid). The DNA-containing liposomes (positively charged on their surface) can fuse with the negatively charged plasma membrane of living cells, due to the neutral co-lipid mediating fusion of the liposome with the cell membrane, allowing nucleic acid cargo molecules to cross into the cytoplasm for replication or expression.
In order for a cell to express a transgene, the nucleic acid must reach the nucleus of the cell to begin transcription. However, the transfected genetic material may never reach the nucleus in the first place, instead being disrupted somewhere along the delivery process. In dividing cells, the material may reach the nucleus by being trapped in the reassembling nuclear envelope following mitosis. But also in non-dividing cells, research has shown that Lipofectamine improves the efficiency of transfection, which suggests that it additionally helps the transfected genetic material penetrate the intact nuclear envelope.
This method of transfection was invented by Dr. Yongliang Chu. | 1 | Applied and Interdisciplinary Chemistry |
Heavy-fermion superconductivity was discovered already in the late 1970s (with CeCuSi being the first example), but the number of heavy-fermion compounds known to superconduct was still very small in the early 1990s, when Christoph Geibel in the group of Frank Steglich found two closely related heavy-fermion superconductors, UNiAl (T=1K) and UPdAl (T=2K), which were published in 1991. At that point, the T=2.0K of UPdAl was the highest critical temperature amongst all known heavy-fermion superconductors, and this record would stand for 10 years until CeCoIn was discovered in 2001. | 1 | Applied and Interdisciplinary Chemistry |
Functional isomers are structural isomers which have different functional groups, resulting in significantly different chemical and physical properties.
An example is the pair propanal HC–CH–C(=O)-H and acetone HC–C(=O)–CH: the first has a –C(=O)H functional group, which makes it an aldehyde, whereas the second has a C–C(=O)–C group, that makes it a ketone.
Another example is the pair ethanol HC–CH–OH (an alcohol) and dimethyl ether HC–O–CHH (an ether). In contrast, 1-propanol and 2-propanol are structural isomers, but not functional isomers, since they have the same significant functional group (the hydroxyl –OH) and are both alcohols.
Besides the different chemistry, functional isomers typically have very different infrared spectra. The infrared spectrum is largely determined by the vibration modes of the molecule, and functional groups like hydroxyl and esters have very different vibration modes. Thus 1-propanol and 2-propanol have relatively similar infrared spectra because of the hydroxyl group, which are fairly different from that of methyl ethyl ether. | 0 | Theoretical and Fundamental Chemistry |
A typical titration begins with a beaker or Erlenmeyer flask containing a very precise amount of the analyte and a small amount of indicator (such as phenolphthalein) placed underneath a calibrated burette or chemistry pipetting syringe containing the titrant. Small volumes of the titrant are then added to the analyte and indicator until the indicator changes color in reaction to the titrant saturation threshold, representing arrival at the endpoint of the titration, meaning the amount of titrant balances the amount of analyte present, according to the reaction between the two. Depending on the endpoint desired, single drops or less than a single drop of the titrant can make the difference between a permanent and temporary change in the indicator. | 0 | Theoretical and Fundamental Chemistry |
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 | Applied and Interdisciplinary Chemistry |
In organic chemistry, amine value is a measure of the nitrogen content of an organic molecule. Specifically, it is usually used to measure the amine content of amine functional compounds. It may be defined as the number of milligrams of potassium hydroxide (KOH) equivalent to one gram of epoxy hardener resin. The units are thus mg KOH/g. | 0 | Theoretical and Fundamental Chemistry |
Streptavidin is a protein purified from the bacterium Streptomyces avidinii, which has a high affinity for biotin. By covalently linking streptavidin and polymers, well defined supramolecular constructs can be created due to the high specificity of
Streptavidin for both biotin and its analogues.
Building upon the covalent core shell strategy, several polymer–streptavidin systems have been developed for affinity separation, bio-sensors and diagnostic applications due to the robust binding conditions and stability of the protein.
Streptavidin can be used as a macro-initiator for in situ ATRP, through grafting from strategy, a stoichiometrically well defined polymer-protein conjugate can be synthesized. Polymer streptavidin systems can also be empowered to cross the cellular membrane by conjugating with cell penetrating molecules such as peptides and membrane disturbing polymers.
Polymer streptavidin systems can also be modulated to respond to certain environmental changes such as pH. By incorporating pH responsive poly(propylacrylic acid) (PPAAc) into the system, tumor cell suppressor p53 and cytochrome C can be delivered into cancer cells efficiently.
For biomolecules that are not hampered by the biotin-streptavidin interaction, iminobiotin, an analogue of biotin, has been applied as a pH-sensitive linker that allows the controlled and reversible assembly and intracellular release of cargo molecules in acidic intracellular compartments. | 1 | Applied and Interdisciplinary Chemistry |
Protein degradation may take place intracellularly or extracellularly. In digestion of food, digestive enzymes may be released into the environment for extracellular digestion whereby proteolytic cleavage breaks proteins into smaller peptides and amino acids so that they may be absorbed and used. In animals the food may be processed extracellularly in specialized organs or guts, but in many bacteria the food may be internalized via phagocytosis. Microbial degradation of protein in the environment can be regulated by nutrient availability. For example, limitation for major elements in proteins (carbon, nitrogen, and sulfur) induces proteolytic activity in the fungus Neurospora crassa as well as in of soil organism communities.
Proteins in cells are broken into amino acids. This intracellular degradation of protein serves multiple functions: It removes damaged and abnormal proteins and prevents their accumulation. It also serves to regulate cellular processes by removing enzymes and regulatory proteins that are no longer needed. The amino acids may then be reused for protein synthesis. | 1 | Applied and Interdisciplinary Chemistry |
Within the focus of bioengineering, various cell modification methods are utilized to alter inherent properties of cells such as growth density, growth rate, growth yield, temperature resistance, freezing tolerance, chemical sensitivity, and vulnerability to pathogens. For example, in 1988 one group of researchers from the Illinois Institute of Technology successfully expressed a Vitreoscilla hemoglobin gene in E. Coli to create a strain that was more tolerant to low-oxygen conditions such as those found in high density industrial bioreactors. | 1 | Applied and Interdisciplinary Chemistry |
Protoplast (), is a biological term coined by Hanstein in 1880 to refer to the entire cell, excluding the cell wall. Protoplasts can be generated by stripping the cell wall from plant, bacterial, or fungal cells by mechanical, chemical or enzymatic means.
Protoplasts differ from spheroplasts in that their cell wall has been completely removed. Spheroplasts retain part of their cell wall. In the case of Gram-negative bacterial spheroplasts, for example, the peptidoglycan component of the cell wall has been removed but the outer membrane component has not. | 1 | Applied and Interdisciplinary Chemistry |
When nutrients build up in a lake, eutrophication occurs, and this generally occurs in the top layer of a lake. The nutrients come both naturally and artificially and usually contain phosphates. The artificial nutrients can come from sewage and fertilizers, from agricultural runoff. Phosphorus from the phosphates causes algae to grow rapidly and spread throughout the top layer of the lake. Algal blooms have negative effects on both the aesthetics and the ecology of the lake. Aesthetically, the lake is not pleasing because it is covered with algae. Ecologically, eutrophication causes organisms in the lake to die because the algae deplete the dissolved oxygen in the lake. | 1 | Applied and Interdisciplinary Chemistry |
There are 4 superfamilies of viruses that cover all RNA-containing viruses with no DNA stage:
* Viruses containing positive-strand RNA or double-strand RNA, except retroviruses and Birnaviridae
** All positive-strand RNA eukaryotic viruses with no DNA stage
** All RNA-containing bacteriophages; there are two families of RNA-containing bacteriophages: Leviviridae (positive ssRNA phages) and Cystoviridae (dsRNA phages)
** dsRNA virus family Reoviridae, Totiviridae, Hypoviridae, Partitiviridae
* Mononegavirales (negative-strand RNA viruses with non-segmented genomes; )
* Negative-strand RNA viruses with segmented genomes (), such as orthomyxoviruses and bunyaviruses
* dsRNA virus family Birnaviridae ()
Flaviviruses produce a polyprotein from the ssRNA genome. The polyprotein is cleaved to a number of products, one of which is NS5, an RNA-dependent RNA polymerase. This RNA-directed RNA polymerase possesses a number of short regions and motifs homologous to other RNA-directed RNA polymerases.
RNA replicase found in positive-strand ssRNA viruses are related to each other, forming three large superfamilies. Birnaviral RNA replicase is unique in that it lacks motif C (GDD) in the palm. Mononegaviral RdRp (PDB 5A22) has been automatically classified as similar to (+)−ssRNA RdRps, specifically one from Pestivirus and one from Leviviridae. Bunyaviral RdRp monomer (PDB 5AMQ) resembles the heterotrimeric complex of Orthomyxoviral (Influenza; PDB 4WSB) RdRp.
Since it is a protein universal to RNA-containing viruses, RdRp is a useful marker for understanding their evolution. The overall structural evolution of viral RdRps has been reviewed. | 1 | Applied and Interdisciplinary Chemistry |
Copper phosphide, , also copper(I) phosphide, cuprous phosphide, cuprophosphorus and phosphor copper, is a compound of copper and phosphorus, a phosphide of copper. It has the appearance of yellowish-grey very brittle mass of crystalline structure. It does not react with water.
Recent crystallographic investigations have proven CuP to be copper deficient, which means that the sum formula of this compound is more accurately expressed as CuP.
Copper phosphide has a role in copper alloys, namely in phosphor bronze. It is a very good deoxidizer of copper.
Copper phosphide can be produced in a reverberatory furnace or in a crucible, e.g. by a reaction of red phosphorus with a copper-rich material. It can also be prepared photochemically, by irradiating cupric hypophosphite with ultraviolet radiation. It can also be produced by reducing copper(II) phosphate with aluminum.
When subjected to ultraviolet light, copper phosphide shows fluorescence.
A blue-black film of copper phosphide forms on white phosphorus when subjected to a solution of copper salt; wounds containing particles of phosphorus therefore have to be washed with 1% solution of copper sulfate. The particles then can be easily removed, which is helped by their fluorescence. Formation of protective layer of copper phosphide is also used in cases of phosphorus ingestion, when gastric lavage with copper sulfate is employed as part of the cure. | 1 | Applied and Interdisciplinary Chemistry |
The Maximum Entropy thermodynamics has some important opposition, in part because of the relative paucity of published results from the MaxEnt school, especially with regard to new testable predictions far-from-equilibrium.
The theory has also been criticized in the grounds of internal consistency. For instance, Radu Balescu provides a strong criticism of the MaxEnt School and of Jaynes work. Balescu states that Jaynes and coworkers theory is based on a non-transitive evolution law that produces ambiguous results. Although some difficulties of the theory can be cured, the theory "lacks a solid foundation" and "has not led to any new concrete result".
Though the maximum entropy approach is based directly on informational entropy, it is applicable to physics only when there is a clear physical definition of entropy. There is no clear unique general physical definition of entropy for non-equilibrium systems, which are general physical systems considered during a process rather than thermodynamic systems in their own internal states of thermodynamic equilibrium. It follows that the maximum entropy approach will not be applicable to non-equilibrium systems until there is found a clear physical definition of entropy. This problem is related to the fact that heat may be transferred from a hotter to a colder physical system even when local thermodynamic equilibrium does not hold so that neither system has a well defined temperature. Classical entropy is defined for a system in its own internal state of thermodynamic equilibrium, which is defined by state variables, with no non-zero fluxes, so that flux variables do not appear as state variables. But for a strongly non-equilibrium system, during a process, the state variables must include non-zero flux variables. Classical physical definitions of entropy do not cover this case, especially when the fluxes are large enough to destroy local thermodynamic equilibrium. In other words, for entropy for non-equilibrium systems in general, the definition will need at least to involve specification of the process including non-zero fluxes, beyond the classical static thermodynamic state variables. The entropy that is maximized needs to be defined suitably for the problem at hand. If an inappropriate entropy is maximized, a wrong result is likely. In principle, maximum entropy thermodynamics does not refer narrowly and only to classical thermodynamic entropy. It is about informational entropy applied to physics, explicitly depending on the data used to formulate the problem at hand. According to Attard, for physical problems analyzed by strongly non-equilibrium thermodynamics, several physically distinct kinds of entropy need to be considered, including what he calls second entropy. Attard writes: "Maximizing the second entropy over the microstates in the given initial macrostate gives the most likely target macrostate.". The physically defined second entropy can also be considered from an informational viewpoint. | 0 | Theoretical and Fundamental Chemistry |
The melting point of ice is at standard pressure; however, pure liquid water can be supercooled well below that temperature without freezing if the liquid is not mechanically disturbed. It can remain in a fluid state down to its homogeneous nucleation point of about . The melting point of ordinary hexagonal ice falls slightly under moderately high pressures, by /atm or about /70 atm as the stabilization energy of hydrogen bonding is exceeded by intermolecular repulsion, but as ice transforms into its polymorphs (see crystalline states of ice) above , the melting point increases markedly with pressure, i.e., reaching at (triple point of Ice VII). | 1 | Applied and Interdisciplinary Chemistry |
An amphoteric substance is one that can act as an acid or as a base, depending on pH. Water (below) is amphoteric. Another example of an amphoteric molecule is the bicarbonate ion that is the conjugate base of the carbonic acid molecule H2CO3 in the equilibrium
but also the conjugate acid of the carbonate ion in (the reverse of) the equilibrium
Carbonic acid equilibria are important for acid–base homeostasis in the human body.
An amino acid is also amphoteric with the added complication that the neutral molecule is subject to an internal acid–base equilibrium in which the basic amino group attracts and binds the proton from the acidic carboxyl group, forming a zwitterion.
At pH less than about 5 both the carboxylate group and the amino group are protonated. As pH increases the acid dissociates according to
At high pH a second dissociation may take place.
Thus the amino acid molecule is amphoteric because it may either be protonated or deprotonated. | 0 | Theoretical and Fundamental Chemistry |
Currently, the stability of most ionic liquids under practical electrochemical conditions is unknown, and the fundamental choice of ionic fluid is still empirical as there is almost no data on metal ion thermodynamics to feed into solubility and speciation models. Also, there are no Pourbaix diagrams available, no standard redox potentials, and bare knowledge of speciation or pH-values. It must be noticed that most processes reported in the literature involving ionic fluids have a Technology Readiness Level (TRL) 3 (experimental proof-of-concept) or 4 (technology validated in the lab), which is a disadvantage for short-term implementation. However, ionometallurgy has the potential to effectively recover metals in a more selective and sustainable way, as it considers environmentally benign solvents, reduction of greenhouse gas emissions and avoidance of corrosive and harmful reagents. | 1 | Applied and Interdisciplinary Chemistry |
In quantum field theory (QFT), the fabric of "empty" space is visualized as consisting of fields, with the field at every point in space and time being a quantum harmonic oscillator, with neighboring oscillators interacting with each other. According to QFT the universe is made up of matter fields whose quanta are fermions (e.g. electrons and quarks), force fields whose quanta are bosons (i.e. photons and gluons) and a Higgs field whose quantum is the Higgs boson. The matter and force fields have zero-point energy. A related term is zero-point field (ZPF), which is the lowest energy state of a particular field. The vacuum can be viewed not as empty space, but as the combination of all zero-point fields.
In QFT the zero-point energy of the vacuum state is called the vacuum energy and the average expectation value of the Hamiltonian is called the vacuum expectation value (also called condensate or simply VEV). The QED vacuum is a part of the vacuum state which specifically deals with quantum electrodynamics (e.g. electromagnetic interactions between photons, electrons and the vacuum) and the QCD vacuum deals with quantum chromodynamics (e.g. color charge interactions between quarks, gluons and the vacuum). Recent experiments advocate the idea that particles themselves can be thought of as excited states of the underlying quantum vacuum, and that all properties of matter are merely vacuum fluctuations arising from interactions with the zero-point field.
Each point in space makes a contribution of , resulting in a calculation of infinite zero-point energy in any finite volume; this is one reason renormalization is needed to make sense of quantum field theories. In cosmology, the vacuum energy is one possible explanation for the cosmological constant and the source of dark energy.
Scientists are not in agreement about how much energy is contained in the vacuum. Quantum mechanics requires the energy to be large as Paul Dirac claimed it is, like a sea of energy. Other scientists specializing in General Relativity require the energy to be small enough for curvature of space to agree with observed astronomy. The Heisenberg uncertainty principle allows the energy to be as large as needed to promote quantum actions for a brief moment of time, even if the average energy is small enough to satisfy relativity and flat space. To cope with disagreements, the vacuum energy is described as a virtual energy potential of positive and negative energy.
In quantum perturbation theory, it is sometimes said that the contribution of one-loop and multi-loop Feynman diagrams to elementary particle propagators are the contribution of vacuum fluctuations, or the zero-point energy to the particle masses. | 0 | Theoretical and Fundamental Chemistry |
The optical absorption spectrum of pyridine in hexane consists of bands at the wavelengths of 195, 251, and 270 nm. With respective extinction coefficients (ε) of 7500, 2000, and 450 L·mol·cm, these bands are assigned to π → π*, π → π*, and n → π* transitions.
The H nuclear magnetic resonance (NMR) spectrum shows signals for α-(δ 8.5), γ-(δ7.5) and β-protons (δ7). By contrast, the proton signal for benzene is found at δ7.27. The larger chemical shifts of the α- and γ-protons in comparison to benzene result from the lower electron density in the α- and γ-positions, which can be derived from the resonance structures. The situation is rather similar for the C NMR spectra of pyridine and benzene: pyridine shows a triplet at δ(α-C) = 150 ppm, δ(β-C) = 124 ppm and δ(γ-C) = 136 ppm, whereas benzene has a single line at 129 ppm. All shifts are quoted for the solvent-free substances. Pyridine is conventionally detected by the gas chromatography and mass spectrometry methods. | 0 | Theoretical and Fundamental Chemistry |
It was historically used as a first-line treatment for hyperthyroidism, as the administration of pharmacologic amounts of iodine leads to temporary inhibition of iodine organification in the thyroid gland, caused by phenomena including the Wolff–Chaikoff effect and the Plummer effect. However it is not used to treat certain autoimmune causes of thyroid disease as iodine-induced blockade of iodine organification may result in hypothyroidism. They are not considered as a first line therapy because of possible induction of resistant hyperthyroidism but may be considered as an adjuvant therapy when used together with other hyperthyroidism medications.
Lugol's iodine has been used traditionally to replenish iodine deficiency. Because of its wide availability as a drinking-water decontaminant, and high content of potassium iodide, emergency use of it was at first recommended to the Polish government in 1986, after the Chernobyl disaster to replace and block any intake of radioactive , even though it was known to be a non-optimal agent, due to its somewhat toxic free-iodine content. Other sources state that pure potassium iodide solution in water (SSKI) was eventually used for most of the thyroid protection after this accident. There is "strong scientific evidence" for potassium iodide thyroid protection to help prevent thyroid cancer. Potassium iodide does not provide immediate protection but can be a component of a general strategy in a radiation emergency.
Historically, Lugols iodine solution has been widely available and used for a number of health problems with some precautions. Lugols is sometimes prescribed in a variety of alternative medical treatments. Only since the end of the Cold War has the compound become subject to national regulation in the English-speaking world. | 0 | Theoretical and Fundamental Chemistry |
The synthesis of borjatriol involved the rare isolation of a migrated epoxide. The diastereomeric mixture of rearrangement products was carried through the remainder of the synthesis.
The final two steps in the total synthesis of spatol involved intramolecular electrophilic trapping of an alkoxide derived from a rearranged epoxide. Attack of the intermediate alkoxide on the adjacent mesylate afforded a bis(epoxide), and debenzylation provided the target compound. | 0 | Theoretical and Fundamental Chemistry |
The leading hadron results from the hadronization of the struck quark. This latter retains the information on its motion inside the nucleon, including its transverse momentum which allows to access the transverse momentum distributions (TMDs) of partons.
Likewise, by detecting the leading hadron, one essentially tags (i.e. identifies) the quark on which the scattering occurred. For example, if the leading hadron is a kaon, we know that the scattering occurred on one of the strange quarks of the nucleon's quark sea. In DIS the struck quark is not identified and the information is an indistinguishable sum over all the quark flavors. SIDIS allows to disentangle this information. | 0 | Theoretical and Fundamental Chemistry |
*Adsorptionsversuche an Gläsern and Filtersubstanzen nach der Methode der radioaktiven Indikatoren. (Adsorption experiments on glasses and filter substances according to the method of radioactive indicators.)
*Radioactive indicators, enteric coatings and intestinal absorption.
*A new method of testing enteric coatings.
*On the Existence of Single Magnetic Poles.
*Pioneer woman in nuclear science. | 0 | Theoretical and Fundamental Chemistry |
He taught courses on General and Inorganic Chemistry, Photochemistry, Supramolecular chemistry. He was chairman of the PhD course on Chemical Sciences from 2002 to 2007 and of the “laurea specialistica” in Photochemistry and Material Chemistry from 2004 to 2007. In the Academic Year 2008–2009, he founded at the University of Bologna an interdisciplinary course on Science and Society. | 0 | Theoretical and Fundamental Chemistry |
Seaborg Technologies is working on a nuclear reactor design in which NaOH is used as a neutron moderator. | 0 | Theoretical and Fundamental Chemistry |
* Protolysis mechanism of cis- and trans-β-chlorovinylmercury chlorides when acted upon by HCl and DCl
* Pd-Catalyzed amination of dibromobiphenyls in the synthesis of macrocycles comprising two biphenyl and two polyamine moieties
* The influence of the substituents in the electrofilic bimolecular reaction
* New trends in the cross-coupling and other catalytic reactions | 0 | Theoretical and Fundamental Chemistry |
Outfalls vary in diameter from as narrow as 15 cm to as wide as 8 m; the widest registered outfall in the world with 8 m diameter is located in Navia (Spain) for the discharge of industrial wastewater. Outfalls vary in length from 50 m to 55 km, the longest registered outfalls being the Boston outfall with a length of 16 km and an industrial outfall in Ankleshwar (India) with a length of 55 km. The depth of the deepest point of an outfall varies from 3 m to up to 60 m, the deepest registered outfall being located in Macuto, Vargas (Venezuela) for the discharge of untreated municipal wastewater.
Outfall materials include polyethylene, stainless steel, carbon steel, glass-reinforced plastic, reinforced concrete, cast iron or tunnels through rock. Common installation methods for pipelines are float and sink, bottom pull and top pull. | 1 | Applied and Interdisciplinary Chemistry |
Gases exhibit by far the greatest space (and, consequently, the weakest intermolecular forces) between their atoms or molecules; since intermolecular interactions are minuscule in comparison to those in liquids and solids, dilute gases very easily form solutions with one another. Air is one such example: it can be more specifically described as a gaseous solution of oxygen and other gases dissolved in nitrogen (its major component). | 0 | Theoretical and Fundamental Chemistry |
Cell-free production of proteins is performed in vitro using purified RNA polymerase, ribosomes, tRNA and ribonucleotides. These reagents may be produced by extraction from cells or from a cell-based expression system. Due to the low expression levels and high cost of cell-free systems, cell-based systems are more widely used. | 1 | Applied and Interdisciplinary Chemistry |
The toxicity of metal carbonyls is due to toxicity of carbon monoxide, the metal, and because of the volatility and instability of the complexes, any inherent toxicity of the metal is generally made much more severe due to ease of exposure. Exposure occurs by inhalation, or for liquid metal carbonyls by ingestion or due to the good fat solubility by skin resorption. Most clinical experience were gained from toxicological poisoning with nickel tetracarbonyl and iron pentacarbonyl due to their use in industry. Nickel tetracarbonyl is considered as one of the strongest inhalation poisons.
Inhalation of nickel tetracarbonyl causes acute non-specific symptoms similar to a carbon monoxide poisoning, such as nausea, cough, headache, fever, and dizziness. After some time, severe pulmonary symptoms such as cough, tachycardia, and cyanosis, or problems in the gastrointestinal tract occur. In addition to pathological alterations of the lung, such as by metalation of the alveoli, damages are observed in the brain, liver, kidneys, adrenal glands, and spleen. A metal carbonyl poisoning often necessitates a lengthy recovery.
Chronic exposure by inhalation of low concentrations of nickel tetracarbonyl can cause neurological symptoms such as insomnia, headaches, dizziness and memory loss. Nickel tetracarbonyl is considered carcinogenic, but it can take 20 to 30 years from the start of exposure to the clinical manifestation of cancer. | 0 | Theoretical and Fundamental Chemistry |
Primary, calibration, and reference materials are only available in small quantities and purchase is often limited to once every few years. Depending on the specific isotope systems and instrumentation, a shortage of available reference materials can be problematic for daily instrument calibrations or for researchers attempting to measure isotope ratios in a large number of natural samples. Rather than using primary materials or reference materials, a laboratory measuring stable isotope ratios will typically purchase a small quantity of the relevant reference materials and measure the isotope ratio of an in-house material against the reference, making that material into a working standard specific to that analytical facility. Once this lab-specific working standard has been calibrated to the international scale the standard is used to measure the isotopic composition of unknown samples. After measurement of both sample and working standard against a third material (commonly called the working gas or the transfer gas) the recorded isotopic distributions are mathematically corrected back to the international scale. It is thus critical to measure the isotopic composition of the working standard with high precision and accuracy (as well as possible given the precision of the instrument and the accuracy of the purchased reference material) because the working standard forms the ultimate basis for accuracy of most mass spectrometric observations. Unlike reference materials, working standards are typically not calibrated across multiple analytical facilities and the accepted δ value measured in a given laboratory could reflect bias specific to a single instrument. However, within a single analytical facility this bias can be removed during data reduction. Because each laboratory defines unique working standards the primary, calibration, and reference materials are long-lived while still ensuring that the isotopic composition of unknown samples can be compared across laboratories. | 0 | Theoretical and Fundamental Chemistry |
A polyoxyanion is a polymeric oxyanion in which multiple oxyanion monomers, usually regarded as polyhedra, are joined by sharing corners or edges. When two corners of a polyhedron are shared the resulting structure may be a chain or a ring. Short chains occur, for example, in polyphosphates. Inosilicates, such as pyroxenes, have a long chain of tetrahedra each sharing two corners. The same structure occurs in so-called meta-vanadates, such as ammonium metavanadate, .
The formula of the oxyanion is obtained as follows: each nominal silicon ion () is attached to two nominal oxide ions () and has a half share in two others. Thus the stoichiometry and charge are given by:
A ring can be viewed as a chain in which the two ends have been joined. Cyclic triphosphate, is an example.
When three corners are shared the structure extends into two dimensions. In amphiboles, (of which asbestos is an example) two chains are linked together by sharing of a third corner on alternate places along the chain. This results in an ideal formula and a linear chain structure which explains the fibrous nature of these minerals. Sharing of all three corners can result in a sheet structure, as in mica, , in which each silicon has one oxygen to itself and a half-share in three others. Crystalline mica can be cleaved into very thin sheets.
The sharing of all four corners of the tetrahedra results in a 3-dimensional structure, such as in quartz. Aluminosilicates are minerals in which some silicon is replaced by aluminium. However, the oxidation state of aluminium is one less than that of silicon, so the replacement must be accompanied by the addition of another cation. The number of possible combinations of such a structure is very large, which is, in part, the reason why there are so many aluminosilicates.
Octahedral units are common in oxyanions of the larger transition metals. Some compounds, such as salts of the chain-polymeric ion, even contain both tetrahedral and octahedral units. Edge-sharing is common in ions containing octahedral building blocks and the octahedra are usually distorted to reduce the strain at the bridging oxygen atoms. This results in 3-dimensional structures called polyoxometalates. Typical examples occur in the Keggin structure of the phosphomolybdate ion. Edge sharing is an effective means of reducing electrical charge density, as can be seen with the hypothetical condensation reaction involving two octahedra:
Here, the average charge on each M atom is reduced by 2. The efficacy of edge-sharing is demonstrated by the following reaction, which occurs when an alkaline aqueous solution of molybdate is acidified.
The tetrahedral molybdate ion is converted into a cluster of 7 edge-linked octahedra giving an average charge on each molybdenum of . The heptamolybdate cluster is so stable that clusters with between 2 and 6 molybdate units have not been detected even though they must be formed as intermediates. | 0 | Theoretical and Fundamental Chemistry |
Iodine gradually sublimes and produces visible fumes on gentle heating at standard atmospheric temperature. It is possible to obtain liquid iodine at atmospheric pressure by controlling the temperature at just between the melting point and the boiling point of iodine. In forensic science, iodine vapor can reveal latent fingerprints on paper. | 0 | Theoretical and Fundamental Chemistry |
Alogliptin, sold under the brand names Nesina and Vipidia, is an oral anti-diabetic drug in the DPP-4 inhibitor (gliptin) class. Like other members of the gliptin class, it causes little or no weight gain, exhibits relatively little risk of hypoglycemia, and has relatively modest glucose-lowering activity. Alogliptin and other gliptins are commonly used in combination with metformin in people whose diabetes cannot adequately be controlled with metformin alone.
In April 2016, the U.S. Food and Drug Administration (FDA) added a warning about increased risk of heart failure. It was developed by Syrrx, a company which was acquired by Takeda Pharmaceutical Company in 2005. In 2020, it was the 295th most commonly prescribed medication in the United States, with more than 1million prescriptions. | 0 | Theoretical and Fundamental Chemistry |
β decay had been first described theoretically by Fermis original ansatz which was Lorentz-invariant and involved a 4-point fermion vector current. However, this did not incorporate parity violation within the matrix element in Fermis Golden Rule seen in weak interactions. The Gamow–Teller theory was necessary for the inclusion of parity violation by modifying the matrix element to include vector and axial-vector couplings of fermions.
This formed the matrix element that completed the Fermi theory of β decay and described parity violation, neutrino helicity, muon decay properties along with the concept of lepton universality. Before the Standard Model of Particle Physics was developed, George Sudarshan and Robert Marshak, and also independently Richard Feynman and Murray Gell-Mann, determined the correct tensor structure (vector minus axial vector, ) of the four-fermion interaction.
From there modern electroweak theory was developed, which described the weak interaction in terms of massive gauge bosons which was required for describing high energy particle cross-sections. | 0 | Theoretical and Fundamental Chemistry |
A rotating-vane vorticity meter was invented by Russian hydraulic engineer A. Ya. Milovich (1874–1958). In 1913 he proposed a cork with four blades attached as a device qualitatively showing the magnitude of the vertical projection of the vorticity and demonstrated a motion-picture photography of the float's motion on the water surface in a model of a river bend.
Rotating-vane vorticity meters are commonly shown in educational films on continuum mechanics (famous examples include the NCFMF's "Vorticity" and "Fundamental Principles of Flow" by Iowa Institute of Hydraulic Research). | 1 | Applied and Interdisciplinary Chemistry |
Charles Moureu attended school in Bayonne. At 17, he apprenticed with his older brother, Félix Moureu, in his brother's pharmacy in Biarritz, in preparation for studies in pharmacy.
From 1884 to 1891 Moureu studied at the École Supérieure de Pharmacie in Paris. He received the school's silver medal in 1886, and both its gold medal and the Laillet Prize in 1887.
In addition, he interned in the Hôpitaux de Paris from 1886 to 1891, where he was given first place rank of the interns in 1887 and in 1889.
Moureu received a degree in 1888 and graduated as a pharmacist first class in 1891, whereupon he was given a position as chief pharmacist of the public asylum of the Seine (des Asiles de la Seine). He remained in this position from 1891 to 1907. This allowed him to continue his research, studying organic chemistry with and Charles Friedel. He received his doctorate in physical sciences in 1893 from the Sorbonne, with the dissertation Contribution à létude de lacide acrylique et de ses dérivés (Contribution to the study of acrylic acid and its derivatives).
He obtained his agrégation in 1899. | 0 | Theoretical and Fundamental Chemistry |
Silicified carbonates can appear as silicified carbonate rock layers, or in the form of silicified karsts. The Paleogene Madrid Basin in Central Spain is a foreland basin resulted from the Alpine uplift, an example of silicified carbonates in rock layers. The lithology consists of carbonate and detritus units that were formed in a lacustrine environment. The rock units are silicified where cherts, quartz, and opaline minerals are found in the layers. It is conformable with the underlying evaporitic beds, also dated from similar ages. It is found that there were two stages of silicification within the rock strata. The earlier stage of silicification provided a better condition and site for the precipitation of silica. The source of silica is still uncertain. There are no biogenic silica detected from the carbonates. However, microbial films in carbonates are found, which could suggest the presence of diatoms.
Karsts are carbonate caves formed from a dissolution of carbonate rocks such as limestones and dolomites. They are usually susceptible to groundwater and are dissolved in these drainage. Silicified karsts and cave deposits are formed when siliceous fluids enter karsts through faults and cracks. The Mid-Proterozoic Mescal Limestone from the Apache Group in central Arizona is classic examples of silicified karsts. A portion of the carbonates are replaced by cherts in early diagenesis and the remaining portion is completely silicified in later stages. The source of silica in carbonates are usually associated with the presence of biogenetic silica; however, the source of silica in Mescal Limestone is from weathering of overlying basalts, which are extrusive igneous rocks that have high silica content. | 0 | Theoretical and Fundamental Chemistry |
The pipette itself is an apparatus comprising following members (see Fig. 2).
: pipette tip configured to be able to access and aspirate/discharge liquid from/into each of vessels, having
::a front end portion,
::a reservoir portion,
::a liquid passage
:::connecting the front end portion and the reservoir portion,
::a separation region
:::in the liquid passage subjected to an action of a magnetic field, and
::a mechanism
:::for applying a negative or positive pressure to the interior of the pipette portion to draw or discharge a magnetic substance suspended liquid into or from the pipette portion
:magnetic field Source
::arranged on the outside of and adjacent to pipette tip; and
:magnetic field source driving device
::for driving the magnetic field source to apply or remove a magnetic field to or from the separation region from outside the liquid passage. When the magnet is brought close to the pipette tip, a magnetic field is applied; when retracted away from the pipette tip, that magnetic field is removed.
A nucleic acid extraction apparatus incorporating Tajima pipettes typically consists of:
:Above mentioned Tajima pipette,
:Plurality of tubes.
: Plurality of tube holder for above mentioned tubes,
:Transport mean
::to transport Tajima pipette among that plurality of tubes (tubes are supported by tube holder), and
:Control device
::for controlling abovementioned devices. | 1 | Applied and Interdisciplinary Chemistry |
Green engineering follows nine guiding principles:
#Engineer processes and products holistically, use systems analysis and integrate environmental impact assessment tools.
#Conserve and improve natural ecosystems while protecting human health and well-being.
#Use life-cycle thinking in all engineering activities.
#Ensure that all material and energy inputs and outputs are as inherently safe and benign as possible.
#Minimize the depletion of natural resources.
#Prevent waste.
#Develop and apply engineering solutions while being cognizant of local geography, aspirations, and cultures.
#Create engineering solutions beyond current or dominant technologies; improve, innovate, and invent (technologies) to achieve sustainability.
#Actively engage communities and stakeholders in development of engineering solutions.
In 2003, The American Chemical Society introduced a new list of twelve principles:
# Inherent Rather Than Circumstantial – Designers need to strive to ensure that all materials and energy inputs and outputs are as inherently nonhazardous as possible.
# Prevention Instead of Treatment – It is better to prevent waste than to treat or clean up waste after it is formed.
# Design for Separation – Separation and purification operations should be designed to minimize energy consumption and materials use.
# Maximize Efficiency – Products, processes, and systems should be designed to maximize mass, energy, space, and time efficiency.
# Output-Pulled Versus Input-Pushed – Products, processes, and systems should be "output pulled" rather than "input pushed" through the use of energy and materials.
# Conserve Complexity – Embedded entropy and complexity must be viewed as an investment when making design choices on recycling, reuse, or beneficial disposition.
# Durability Rather Than Immortality – Targeted durability, not immortality, should be a design goal.
# Meet Need, Minimize Excess – Design for unnecessary capacity or capability (e.g., "one size fits all") solutions should be considered a design flaw.
# Minimize Material Diversity – Material diversity in multicomponent products should be minimized to promote disassembly and value retention.
# Integrate Material and Energy Flows – Design of products, processes, and systems must include integration and interconnectivity with available energy and materials flows.
# Design for Commercial "Afterlife" – Products, processes, and systems should be designed for performance in a commercial "afterlife."
# Renewable Rather Than Depleting – Material and energy inputs should be renewable rather than depleting. | 1 | Applied and Interdisciplinary Chemistry |
In chemical synthesis, click chemistry is a class of simple, atom-economy reactions commonly used for joining two molecular entities of choice. Click chemistry is not a single specific reaction, but describes a way of generating products that follow examples in nature, which also generates substances by joining small modular units. In many applications, click reactions join a biomolecule and a reporter molecule. Click chemistry is not limited to biological conditions: the concept of a "click" reaction has been used in chemoproteomic, pharmacological, biomimetic and molecular machinery applications. However, they have been made notably useful in the detection, localization and qualification of biomolecules.
Click reactions occur in one pot, are not disturbed by water, generate minimal and inoffensive byproducts, and are "spring-loaded"—characterized by a high thermodynamic driving force that drives it quickly and irreversibly to high yield of a single reaction product, with high reaction specificity (in some cases, with both regio- and stereo-specificity). These qualities make click reactions particularly suitable to the problem of isolating and targeting molecules in complex biological environments. In such environments, products accordingly need to be physiologically stable and any byproducts need to be non-toxic (for in vivo systems).
By developing specific and controllable bioorthogonal reactions, scientists have opened up the possibility of hitting particular targets in complex cell lysates. Recently, scientists have adapted click chemistry for use in live cells, for example using small molecule probes that find and attach to their targets by click reactions. Despite challenges of cell permeability, bioorthogonality, background labeling, and reaction efficiency, click reactions have already proven useful in a new generation of pulldown experiments (in which particular targets can be isolated using, for instance, reporter molecules which bind to a certain column), and fluorescence spectrometry (in which the fluorophore is attached to a target of interest and the target quantified or located). More recently, novel methods have been used to incorporate click reaction partners onto and into biomolecules, including the incorporation of unnatural amino acids containing reactive groups into proteins and the modification of nucleotides. These techniques represent a part of the field of chemical biology, in which click chemistry plays a fundamental role by intentionally and specifically coupling modular units to various ends.
The term "click chemistry" was coined by K. Barry Sharpless' wife, Jan Dueser, in 1998, and was first fully described by Sharpless, Hartmuth C. Kolb, and M.G. Finn of The Scripps Research Institute in 2001. In 2022, the Nobel Prize in Chemistry was jointly awarded to Carolyn R. Bertozzi, Morten P. Meldal and K. Barry Sharpless, "for the development of click chemistry and bioorthogonal chemistry". | 0 | Theoretical and Fundamental Chemistry |
A depolarizing neuromuscular blocking agent is a form of neuromuscular blocker that depolarizes the motor end plate. An example is succinylcholine. Depolarizing blocking agents work by depolarizing the plasma membrane of the muscle fiber, similar to acetylcholine. However, these agents are more resistant to degradation by acetylcholinesterase, the enzyme responsible for degrading acetylcholine, and can thus more persistently depolarize the muscle fibers. This differs from acetylcholine, which is rapidly degraded and only transiently depolarizes the muscle.
There are two phases to the depolarizing block. During phase I (depolarizing phase), succinylcholine interacts with nicotinic receptor to open the channel and cause depolarization of the end plate, which later spread to and result in depolarization of adjacent membranes. As a result, there is disorganisation of contraction of muscle motor unit. This causes muscular fasciculations (muscle twitches) while they are depolarizing the muscle fibers. Eventually, after sufficient depolarization has occurred, phase II (desensitizing phase) sets in and the muscle is no longer responsive to acetylcholine released by the motoneurons. At this point, full neuromuscular block has been achieved. Phase I block effect can be increased by cholinesterase inhibitors which further delay the action of metabolism and removal by cholinesterase.
Under continuous exposure to succinylcholine, the initial end plate depolarization is reduced, and repolarisation process is initiated. As a result of the widespread sustained depolarization the synapses ultimately begin repolarization. Once repolarized, the membrane is still less susceptible to additional depolarization (phase II block).
The prototypical depolarizing blocking drug is succinylcholine (suxamethonium). It is the only such drug used clinically. It has a rapid onset (30 seconds) but very short duration of action (5–10 minutes) because of hydrolysis by various cholinesterases (such as butyrylcholinesterase in the blood). The patient will experience fasciculation due to the depolarisation of muscle neurone fibres and seconds later, flaccid paralysis will occur. Succinylcholine was originally known as diacetylcholine because structurally it is composed of two acetylcholine molecules joined with a methyl group. Decamethonium is sometimes, but rarely, used in clinical practice.
It is indicated for rapid sequence intubation. | 1 | Applied and Interdisciplinary Chemistry |
Boundary conditions in fluid dynamics are the set of constraints to boundary value problems in computational fluid dynamics. These boundary conditions include inlet boundary conditions, outlet boundary conditions, wall boundary conditions, constant pressure boundary conditions, axisymmetric boundary conditions, symmetric boundary conditions, and periodic or cyclic boundary conditions.
Transient problems require one more thing i.e., initial conditions where initial values of flow variables are specified at nodes in the flow domain. Various types of boundary conditions are used in CFD for different conditions and purposes and are discussed as follows. | 1 | Applied and Interdisciplinary Chemistry |
Many carbonyl compounds exhibit keto–enol tautomerism. This effect is especially pronounced in 1,3-dicarbonyl compounds that can form hydrogen-bonded enols. The equilibrium constant is dependent upon the solvent polarity, with the cis-enol form predominating at low polarity and the diketo form predominating at high polarity. The intramolecular H-bond formed in the cis-enol form is more pronounced when there is no competition for intermolecular H-bonding with the solvent. As a result, solvents of low polarity that do not readily participate in H-bonding allow cis-enolic stabilization by intramolecular H-bonding. | 0 | Theoretical and Fundamental Chemistry |
In New Zealand, pseudoephedrine is currently classified as a Class B Part II controlled drug in the Misuse of Drugs Act 1975, making it illegal to supply or possess except on prescription.
Pseudoephedrine, ephedrine, and any product containing these substances, e.g. cold and flu medicines, were first classified in October 2004 as Class C Part III (partially exempted) controlled drugs, due to being the principal ingredient in methamphetamine. New Zealand Customs and police officers continued to make large interceptions of precursor substances believed to be destined for methamphetamine production. On 9 October 2009, Prime Minister John Key announced pseudoephedrine-based cold and flu tablets would become prescription-only drugs and reclassified as a class B2 drug. The law was amended by The Misuse of Drugs Amendment Bill 2010, which passed in August 2011.
On 24 November 2023, the recently-formed National-led coalition government announced that the sale of cold medication containing pseudoephedrine would be allowed (as part of the coalition agreement between the National and ACT parties). | 0 | Theoretical and Fundamental Chemistry |
All redox reactions take place in the hydrophilic domain of complex I. NADH initially binds to complex I, and transfers two electrons to the flavin mononucleotide (FMN) prosthetic group of the enzyme, creating FMNH. The electron acceptor – the isoalloxazine ring – of FMN is identical to that of FAD. The electrons are then transferred through the FMN via a series of iron-sulfur (Fe-S) clusters, and finally to coenzyme Q10 (ubiquinone). This electron flow changes the redox state of the protein, inducing conformational changes of the protein which alters the pK values of ionizable side chain, and causes four hydrogen ions to be pumped out of the mitochondrial matrix. Ubiquinone (CoQ) accepts two electrons to be reduced to ubiquinol (CoQH). | 1 | Applied and Interdisciplinary Chemistry |
Total inorganic carbon (C or TIC) is the sum of the inorganic carbon species.
Carbon compounds can be distinguished as either organic or inorganic, and dissolved or particulate, depending on their composition. Organic carbon forms the backbone of key components of organic compounds such as proteins, lipids, carbohydrates, and nucleic acids. Inorganic carbon is found primarily in simple compounds such as carbon dioxide (), carbonic acid (), bicarbonate (), and carbonate (). | 0 | Theoretical and Fundamental Chemistry |
The Australasian Institute of Mining and Metallurgy (AusIMM) provides services to professionals engaged in all facets of the global minerals sector and is based in Carlton, Victoria, Australia. | 1 | Applied and Interdisciplinary Chemistry |
Hypothermia is often defined as any body temperature below . With this method it is divided into degrees of severity based on the core temperature.
Another classification system, the Swiss staging system, divides hypothermia based on the presenting symptoms which is preferred when it is not possible to determine an accurate core temperature.
Other cold-related injuries that can be present either alone or in combination with hypothermia include:
*Chilblains: condition caused by repeated exposure of skin to temperatures just above freezing. The cold causes damage to small blood vessels in the skin. This damage is permanent and the redness and itching will return with additional exposure. The redness and itching typically occurs on cheeks, ears, fingers, and toes.
*Frostbite: the freezing and destruction of tissue, which happens below the freezing point of water
*Frostnip: a superficial cooling of tissues without cellular destruction
*Trench foot or immersion foot: a condition caused by repetitive exposure to water at non-freezing temperatures
The normal human body temperature is often stated as . Hyperthermia and fever, are defined as a temperature of greater than . | 1 | Applied and Interdisciplinary Chemistry |
Both the vancomycin aglycone and the complete vancomycin molecule have been targets successfully reached by total synthesis. The target was first achieved by David Evans in October 1998, KC Nicolaou in December 1998, Dale Boger in 1999, and has recently been more selectively synthesized again by Dale Boger in 2020. | 0 | Theoretical and Fundamental Chemistry |
The sponge bomb was developed by the Israel Defense Forces (IDF) to address the use of tunnels by Hamas in Gaza. | 0 | Theoretical and Fundamental Chemistry |
The energy U stored in an electrostatic field distribution is:Knowing the magnitude of the electric field of an ion in a medium of dielectric constant ε is and the volume element can be expressed as , the energy can be written as: Thus, the energy of solvation of the ion from gas phase (ε =1) to a medium of dielectric constant ε is: | 0 | Theoretical and Fundamental Chemistry |
Methane, the main constituent of natural gas can be produced from algae in various methods, namely gasification, pyrolysis and anaerobic digestion. In gasification and pyrolysis methods methane is extracted under high temperature and pressure. Anaerobic digestion is a straightforward method involved in decomposition of algae into simple components then transforming it into fatty acids using microbes like acidogenic bacteria followed by removing any solid particles and finally adding methanogenic archaea to release a gas mixture containing methane. A number of studies have successfully shown that biomass from microalgae can be converted into biogas via anaerobic digestion. Therefore, in order to improve the overall energy balance of microalgae cultivation operations, it has been proposed to recover the energy contained in waste biomass via anaerobic digestion to methane for generating electricity. | 1 | Applied and Interdisciplinary Chemistry |
Aequorin is a holoprotein composed of two distinct units, the apoprotein that is called apoaequorin, which has an approximate molecular weight of 21 kDa, and the prosthetic group coelenterazine, the luciferin. This is to say, apoaequorin is the enzyme produced in the photocytes of the animal, and coelenterazine is the substrate whose oxidation the enzyme catalyzes. When coelenterazine is bound, it is called aequorin. Notably, the protein contains three EF hand motifs that function as binding sites for Ca ions. The protein is a member of the superfamily of the calcium-binding proteins, of which there are some 66 subfamilies.
The crystal structure revealed that aequorin binds coelenterazine and oxygen in the form of a peroxide, coelenterazine-2-hydroperoxide. The binding site for the first two calcium atoms show a 20 times greater affinity for calcium than the third site. However, earlier claims that only two EF-hands bind calcium were questioned when later structures indicated that all three sites can indeed bind calcium. Thus, titration studies show that all three calcium-binding sites are active but only two ions are needed to trigger the enzymatic reaction.
Other studies have shown the presence of an internal cysteine bond that maintains the structure of aequorin. This has also explained the need for a thiol reagent like beta mercaptoethanol in the regeneration of the protein since such reagents weaken the sulfhydryl bonds between cysteine residues, expediting the regeneration of the aequorin.
Chemical characterization of aequorin indicates the protein is somewhat resilient to harsh treatments. Aequorin is heat resistant. Held at 95 °C for 2 minutes the protein lost only 25% activity. Denaturants such as 6-M urea or 4-M guanidine hydrochloride did not destroy the protein. | 1 | Applied and Interdisciplinary Chemistry |
3α-Etiocholanediol, or simply etiocholanediol, also known as 3α,5β-androstanediol or as etiocholane-3α,17β-diol, is a naturally occurring etiocholane (5β-androstane) steroid and an endogenous metabolite of testosterone. It is formed from 5β-dihydrotestosterone (after 5β-reduction of testosterone) and is further transformed into etiocholanolone. | 1 | Applied and Interdisciplinary Chemistry |
The impetus for development of selective COX-2 inhibitors was the adverse gastrointestinal side-effects of NSAIDs. Soon after the discovery of the mechanism of action of NSAIDs, strong indications emerged for alternative forms of COX, but little supporting evidence was found. COX enzyme proved to be difficult to purify and was not sequenced until 1988. In 1991 the existence of the COX-2 enzyme was confirmed by being cloned by Dr. Dan Simmons at Brigham Young University. Before the confirmation of COX-2 existence, the Dupont company had developed a compound, DuP-697, that was potent in many anti-inflammatory assays but did not have the ulcerogenic effects of NSAIDs. Once the COX-2 enzyme was identified, Dup-697 became the building-block for synthesis of COX-2 inhibitors. Celecoxib and rofecoxib, the first COX-2 inhibitors to reach market, were based on DuP-697. It took less than eight years to develop and market the first COX-2 inhibitor, with Celebrex (celecoxib) launched in December 1998 and Vioxx (rofecoxib) launched in May 1999. Celecoxib and other COX-2 selective inhibitors, valdecoxib, parecoxib, and mavacoxib, were discovered by a team at the Searle division of Monsanto led by John Talley. | 1 | Applied and Interdisciplinary Chemistry |
Serinolamide A is a cannabinoid structurally related to endocannabinoids found in cyanobacteria such as Lyngbya majuscula and other species in the Oscillatoria family. | 1 | Applied and Interdisciplinary Chemistry |
Type P (55%Pd/31%Pt/14%Au–65%Au/35%Pd, by weight) thermocouples give a thermoelectric voltage that mimics the type K over the range 500 °C to 1400 °C, however they are constructed purely of noble metals and so shows enhanced corrosion resistance. This combination is also known as Platinel II. | 1 | Applied and Interdisciplinary Chemistry |
Dispersion is a process that occurs in soils that are particularly vulnerable to erosion by water. In soil layers where clays are saturated with sodium ions ("sodic soils"), soil can break down very easily into fine particles and wash away. This can lead to a variety of soil and water quality problems, including:
* large soil losses by gully erosion and tunnel erosion
* Soil structural degradation, clogging and sealing where dispersed particles settle
* Suspended soil causing turbidity in water and transporting nutrients off the land. | 0 | Theoretical and Fundamental Chemistry |
Clinical trials are classified by the research objective created by the investigators.
* In an observational study, the investigators observe the subjects and measure their outcomes. The researchers do not actively manage the study.
* In an interventional study, the investigators give the research subjects an experimental drug, surgical procedure, use of a medical device, diagnostic or other intervention to compare the treated subjects with those receiving no treatment or the standard treatment. Then the researchers assess how the subjects' health changes.
Trials are classified by their purpose. After approval for human research is granted to the trial sponsor, the U.S. Food and Drug Administration (FDA) organizes and monitors the results of trials according to type:
* Prevention trials look for ways to prevent disease in people who have never had the disease or to prevent a disease from returning. These approaches may include drugs, vitamins or other micronutrients, vaccines, or lifestyle changes.
* Screening trials test for ways to identify certain diseases or health conditions.
* Diagnostic trials are conducted to find better tests or procedures for diagnosing a particular disease or condition.
* Treatment trials test experimental drugs, new combinations of drugs, or new approaches to surgery or radiation therapy.
* Quality of life trials (supportive care trials) evaluate how to improve comfort and quality of care for people with a chronic illness.
* Genetic trials are conducted to assess the prediction accuracy of genetic disorders making a person more or less likely to develop a disease.
* Epidemiological trials have the goal of identifying the general causes, patterns or control of diseases in large numbers of people.
* Compassionate use trials or expanded access trials provide partially tested, unapproved therapeutics to a small number of patients who have no other realistic options. Usually, this involves a disease for which no effective therapy has been approved, or a patient who has already failed all standard treatments and whose health is too compromised to qualify for participation in randomized clinical trials. Usually, case-by-case approval must be granted by both the FDA and the pharmaceutical company for such exceptions.
* Fixed trials consider existing data only during the trial's design, do not modify the trial after it begins, and do not assess the results until the study is completed.
* Adaptive clinical trials use existing data to design the trial, and then use interim results to modify the trial as it proceeds. Modifications include dosage, sample size, drug undergoing trial, patient selection criteria and "cocktail" mix. Adaptive trials often employ a Bayesian experimental design to assess the trial's progress. In some cases, trials have become an ongoing process that regularly adds and drops therapies and patient groups as more information is gained. The aim is to more quickly identify drugs that have a therapeutic effect and to zero in on patient populations for whom the drug is appropriate.
Clinical trials are conducted typically in four phases, with each phase using different numbers of subjects and having a different purpose to construct focus on identifying a specific effect. | 1 | Applied and Interdisciplinary Chemistry |
Many microbes (phototrophs) are capable of using light as a source of energy to produce ATP and organic compounds such as carbohydrates, lipids, and proteins. Of these, algae are particularly significant because they are oxygenic, using water as an electron donor for electron transfer during photosynthesis. Phototrophic bacteria are found in the phyla "Cyanobacteria", Chlorobiota, Pseudomonadota, Chloroflexota, and Bacillota. Along with plants these microbes are responsible for all biological generation of oxygen gas on Earth. Because chloroplasts were derived from a lineage of the Cyanobacteria, the general principles of metabolism in these endosymbionts can also be applied to chloroplasts. In addition to oxygenic photosynthesis, many bacteria can also photosynthesize anaerobically, typically using sulfide () as an electron donor to produce sulfate. Inorganic sulfur (), thiosulfate () and ferrous iron () can also be used by some organisms. Phylogenetically, all oxygenic photosynthetic bacteria are Cyanobacteria, while anoxygenic photosynthetic bacteria belong to the purple bacteria (Pseudomonadota), Green sulfur bacteria (e.g., Chlorobium), Green non-sulfur bacteria (e.g., Chloroflexus), or the heliobacteria (Low %G+C Gram positives). In addition to these organisms, some microbes (e.g. the Archaeon Halobacterium or the bacterium Roseobacter, among others) can utilize light to produce energy using the enzyme bacteriorhodopsin, a light-driven proton pump. However, there are no known Archaea that carry out photosynthesis.
As befits the large diversity of photosynthetic bacteria, there are many different mechanisms by which light is converted into energy for metabolism. All photosynthetic organisms locate their photosynthetic reaction centers within a membrane, which may be invaginations of the cytoplasmic membrane (Pseudomonadota), thylakoid membranes ("Cyanobacteria"), specialized antenna structures called chlorosomes (Green sulfur and non-sulfur bacteria), or the cytoplasmic membrane itself (heliobacteria). Different photosynthetic bacteria also contain different photosynthetic pigments, such as chlorophylls and carotenoids, allowing them to take advantage of different portions of the electromagnetic spectrum and thereby inhabit different niches. Some groups of organisms contain more specialized light-harvesting structures (e.g. phycobilisomes in Cyanobacteria and chlorosomes in Green sulfur and non-sulfur bacteria), allowing for increased efficiency in light utilization.
Biochemically, anoxygenic photosynthesis is very different from oxygenic photosynthesis. Cyanobacteria (and by extension, chloroplasts) use the Z scheme of electron flow in which electrons eventually are used to form NADH. Two different reaction centers (photosystems) are used and proton motive force is generated both by using cyclic electron flow and the quinone pool. In anoxygenic photosynthetic bacteria, electron flow is cyclic, with all electrons used in photosynthesis eventually being transferred back to the single reaction center. A proton motive force is generated using only the quinone pool. In heliobacteria, Green sulfur, and Green non-sulfur bacteria, NADH is formed using the protein ferredoxin, an energetically favorable reaction. In purple bacteria, NADH is formed by reverse electron flow due to the lower chemical potential of this reaction center. In all cases, however, a proton motive force is generated and used to drive ATP production via an ATPase.
Most photosynthetic microbes are autotrophic, fixing carbon dioxide via the Calvin cycle. Some photosynthetic bacteria (e.g. Chloroflexus) are photoheterotrophs, meaning that they use organic carbon compounds as a carbon source for growth. Some photosynthetic organisms also fix nitrogen (see below). | 1 | Applied and Interdisciplinary Chemistry |
In 1540, Vannoccio Biringuccio publishes his De la pirotechnia, the first systematic book on metallurgy, in 1556 Georg Agricola writes De Re Metallica, an influential book on metallurgy and mining, and glass lens are developed in the Netherlands and used for the first time in microscopes and telescopes.
In the 17th century, Galileo's Two New Sciences (strength of materials and kinematics) includes the first quantitative statements in the science of materials.
In the 18th century, William Champion patents a process for the production of metallic zinc by distillation from calamine and charcoal, Bryan Higgins was issued a patent for hydraulic cement (stucco) for use as an exterior plaster, and Alessandro Volta makes a copper or zinc acid battery.
In the 19th century, Thomas Johann Seebeck invents the thermocouple, Joseph Aspin invents Portland cement, Charles Goodyear invents vulcanized rubber, Louis Daguerre and William Fox Talbot invent silver-based photographic processes, James Clerk Maxwell demonstrates color photography, and Charles Fritts makes the first solar cells using selenium waffles.
Before the early 1800s, aluminum had not been produced as an isolated metal. It wasn't until 1825 that; Hans Christian Ørsted discovered how to create elemental aluminum via the reduction of aluminum chloride. Since aluminum is a light element with good mechanical properties, it was widely sought to replace heavier less functional metals like silver and gold. Napoleon III used aluminum plates and utensils for his honored guests, while the rest were given silver. However, this process was still expensive and was still not able to produce the metal in large quantities.
In 1886, American Charles Martin Hall and Frenchman Paul Héroult invented a process completely independent of each other to produce aluminum from aluminum oxide via electrolysis. This process would allow aluminum to be manufactured cheaper than ever before, and laid the groundwork for turning the element from a precious metal into an easily obtainable commodity. Around the same time in 1888, Carl Josef Bayer was working in St Petersburg, Russia to develop a method to make pure alumina for the textile industry. This process involved dissolving the aluminum oxide out of the bauxite mineral to produce gibbsite, which can then be purified back into raw alumina. The Bayer process and the Hall-Héroult process are still used today to produce a majority of the world's alumina and aluminum. | 1 | Applied and Interdisciplinary Chemistry |
Because the hypothalamus/osmoreceptor system ordinarily works well to cause drinking or urination to restore the bodys sodium concentrations to normal, this system can be used in medical treatment to regulate the bodys total fluid content, by first controlling the body's sodium content. Thus, when a powerful diuretic drug is given which causes the kidneys to excrete sodium, the effect is accompanied by an excretion of body water (water loss accompanies sodium loss). This happens because the kidney is unable to efficiently retain water while excreting large amounts of sodium. In addition, after sodium excretion, the osmoreceptor system may sense lowered sodium concentration in the blood and then direct compensatory urinary water loss in order to correct the hyponatremic (low blood sodium) state. | 1 | Applied and Interdisciplinary Chemistry |
PCAF has been shown to interact with:
* BRCA2,
* CTNNB1,
* CREBBP,
* EVI1,
* HNF1A,
* IRF1,
* IRF2,
* KLF13,
* Mdm2
* Myc,
* NCOA1,
* POLR2A,
* RBPJ,
* TCF3,
* TRRAP, and
* TWIST1. | 1 | Applied and Interdisciplinary Chemistry |
In chemistry, a hydride is formally the anion of hydrogen (H), a hydrogen atom with two electrons. The term is applied loosely. At one extreme, all compounds containing covalently bound H atoms are also called hydrides: water (HO) is a hydride of oxygen, ammonia is a hydride of nitrogen, etc. For inorganic chemists, hydrides refer to compounds and ions in which hydrogen is covalently attached to a less electronegative element. In such cases, the H centre has nucleophilic character, which contrasts with the protic character of acids. The hydride anion is very rarely observed.
Almost all of the elements form binary compounds with hydrogen, the exceptions being He, Ne, Ar, Kr, Pm, Os, Ir, Rn, Fr, and Ra. Exotic molecules such as positronium hydride have also been made. | 0 | Theoretical and Fundamental Chemistry |
The Society of Chemical Industry (America Section) or SCI America is an independent learned society inspired by the creation of the Society of Chemical Industry (SCI) in London in 1881. Originally known as the New York Section, it was formed in 1894 and officially renamed the America Section in 1919. The main activity of the America Section is the awarding of several prizes in chemistry: the Perkin Medal, the Chemical Industry Medal and the Gordon E. Moore Medal. The America Section also works with the American Chemical Society (ACS) and the American Institute of Chemical Engineers (AIChE) to support underserved and Black scholars in chemistry and chemical engineering. | 1 | Applied and Interdisciplinary Chemistry |
In chemistry, the empirical formula of a chemical compound is the simplest whole number ratio of atoms present in a compound. A simple example of this concept is that the empirical formula of sulfur monoxide, or SO, would simply be SO, as is the empirical formula of disulfur dioxide, SO. Thus, sulfur monoxide and disulfur dioxide, both compounds of sulfur and oxygen, have the same empirical formula. However, their molecular formulas, which express the number of atoms in each molecule of a chemical compound, are not the same.
An empirical formula makes no mention of the arrangement or number of atoms. It is standard for many ionic compounds, like calcium chloride (CaCl), and for macromolecules, such as silicon dioxide (SiO).
The molecular formula, on the other hand, shows the number of each type of atom in a molecule. The structural formula shows the arrangement of the molecule. It is also possible for different types of compounds to have equal empirical formulas.
In the early days of chemistry, information regarding the composition of compounds came from elemental analysis, which gives information about the relative amounts of elements present in a compound, which can be written as percentages or mole ratios. However, chemists were not able to determine the exact amounts of these elements and were only able to know their ratios, hence the name "empirical formula". Since ionic compounds are extended networks of anions and cations, all formulas of ionic compounds are empirical. | 0 | Theoretical and Fundamental Chemistry |
Structural isomers have the same number of atoms of each element (hence the same molecular formula), but the atoms are connected in distinct ways. | 0 | Theoretical and Fundamental Chemistry |
Stakeholder Program on Agent Detection Assays (SPADA) brings together expert stakeholders from the biothreat community to foster a comprehensive and uniform approach to scientific analysis and detection of biothreat agents. | 0 | Theoretical and Fundamental Chemistry |
RNA-Seq (named as an abbreviation of RNA sequencing) is a technique that uses next-generation sequencing to reveal the presence and quantity of RNA molecules in a biological sample, providing a snapshot of gene expression in the sample, also known as transcriptome.
Specifically, RNA-Seq facilitates the ability to look at alternative gene spliced transcripts, post-transcriptional modifications, gene fusion, mutations/SNPs and changes in gene expression over time, or differences in gene expression in different groups or treatments. In addition to mRNA transcripts, RNA-Seq can look at different populations of RNA to include total RNA, small RNA, such as miRNA, tRNA, and ribosomal profiling. RNA-Seq can also be used to determine exon/intron boundaries and verify or amend previously annotated 5 and 3 gene boundaries. Recent advances in RNA-Seq include single cell sequencing, bulk RNA sequencing, in situ sequencing of fixed tissue, and native RNA molecule sequencing with single-molecule real-time sequencing. Other examples of emerging RNA-Seq applications due to the advancement of bioinformatics algorithms are copy number alteration, microbial contamination, transposable elements, cell type (deconvolution) and the presence of neoantigens.
Prior to RNA-Seq, gene expression studies were done with hybridization-based microarrays. Issues with microarrays include cross-hybridization artifacts, poor quantification of lowly and highly expressed genes, and needing to know the sequence a priori. Because of these technical issues, transcriptomics transitioned to sequencing-based methods. These progressed from Sanger sequencing of Expressed sequence tag libraries, to chemical tag-based methods (e.g., serial analysis of gene expression), and finally to the current technology, next-gen sequencing of complementary DNA (cDNA), notably RNA-Seq. | 1 | Applied and Interdisciplinary Chemistry |
Defining non-dimensional plate length , non-dimensional plate edge depth , and non-dimensional load , Burton and Bush derived the following analytical results:
<br />
<br />
The equations for and give the configuration parameters that give the maximum value of . For further insight, it is helpful to examine various regimes of the non-dimensional plate length, . | 1 | Applied and Interdisciplinary Chemistry |
Flash vacuum pyrolysis (FVP) is a technique in organic synthesis. It entails heating a precursor molecule intensely and briefly. Two key parameters are the temperature and duration (or residence time), which are adjusted to optimize yield, conversion, and avoidance of intractable products. Often the experiment entails volatilizing a precursor, which is drawn through a "hot zone" followed by rapid condensation. The apparatus typically is conducted under dynamic vacuum. The hot zone must impart heat to the gaseous molecules, so it is generally packed with solids to induce gas-solid collisions. The packing material is generally chemically inert, such as quartz. The precursor (i) volatilizes with gentle heating and under vacuum, (ii) the precursor fragments or rearranges in the hot zone, and finally (iii) the products are collected by rapid cooling. Rapid post-reaction cooling and the dilution inherent in gases both suppress bimolecular degradation pathways. | 0 | Theoretical and Fundamental Chemistry |
Alkali metal nitrates are chemical compounds consisting of an alkali metal (lithium, sodium, potassium, rubidium and caesium) and the nitrate ion. Only two are of major commercial value, the sodium and potassium salts. They are white, water-soluble salts with melting points ranging from 255 °C () to 414 °C () on a relatively narrow span of 159 °C
The melting point of the alkali metal nitrates tends to increase from 255 °C to 414 °C (with an anomaly for rubidium being not properly aligned in the series) as the atomic mass and the ionic radius (naked cation) of the alkaline metal increases, going down in the column. Similarly, but not presented here in the table, the solubility of these salts in water also decreases with the atomic mass of the metal. | 0 | Theoretical and Fundamental Chemistry |
The study of MA structure and function is challenging, in particular because of their megadalton size, but also because of their complex compositions and varying dynamic natures. Most have had standard chemical and biochemical methods applied (methods of protein purification and centrifugation, chemical and electrochemical characterization, etc.). In addition, their methods of study include modern proteomic approaches, computational and atomic-resolution structural methods (e.g., X-ray crystallography), small-angle X-ray scattering (SAXS) and small-angle neutron scattering (SANS), force spectroscopy, and transmission electron microscopy and cryo-electron microscopy. Aaron Klug was recognized with the 1982 Nobel Prize in Chemistry for his work on structural elucidation using electron microscopy, in particular for protein-nucleic acid MAs including the tobacco mosaic virus (a structure containing a 6400 base ssRNA molecule and >2000 coat protein molecules). The crystallization and structure solution for the ribosome, MW ~ 2.5 MDa, an example of part of the protein synthetic machinery of living cells, was object of the 2009 Nobel Prize in Chemistry awarded to Venkatraman Ramakrishnan, Thomas A. Steitz, and Ada E. Yonath. | 1 | Applied and Interdisciplinary Chemistry |
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