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Only 20.35% of the catchment of the lake is covered by forest.
Demographic growth and lack of employment are some of the factors that have promoted conversion of forested areas into subsistence agriculture, especially following the coffee price crisis.
The loss of forest cover is particularly critical on steep terrains, which are most susceptible to overland flow and erosion. Soil loss results in siltation farther downslope, as well as in streams and in the lake. It also decreases water recharge of the deep aquifers. | 1 | Applied and Interdisciplinary Chemistry |
In coordination chemistry, a pi-donor ligand is a kind of ligand endowed with filled non-bonding orbitals that overlap with metal-based orbitals. Their interaction is complementary to the behavior of pi-acceptor ligands. The existence of terminal oxo ligands for the early transition metals is one consequence of this kind of bonding. Classic pi-donor ligands are oxide (O), nitride (N), imide (RN), alkoxide (RO), amide (RN), and fluoride. For late transition metals, strong pi-donors form anti-bonding interactions with the filled d-levels, with consequences for spin state, redox potentials, and ligand exchange rates. Pi-donor ligands are low in the spectrochemical series. | 0 | Theoretical and Fundamental Chemistry |
After graduating the Winter school 2, students take Final KChO. It is held on January or February. It is divided into two parts; Theories and Experiments. Organic Chemistry and Inorganic Chemistry questions in the theory are important for choosing the representatives. In the experiment, students solve one Organic Chemistry experiment and one Quantitative Chemistry experiment. Four students who got a high score represents South Korea in IChO. If all the four representatives are the same gender, the student who got a highest score between the other gender who ranked eighth or higher becomes the representative instead of the fourth student. | 1 | Applied and Interdisciplinary Chemistry |
Neurotransmitters are tiny signal molecules stored in membrane-enclosed synaptic vesicles and released via exocytosis. Indeed, a change in electrical potential in the presynaptic cell triggers the release of these molecules. By attaching to transmitter-gated ion channels, the neurotransmitter causes an electrical alteration in the postsynaptic cell and rapidly diffuses across the synaptic cleft. Once released, the neurotransmitter is swiftly eliminated, either by being absorbed by the nerve terminal that produced it, taken up by nearby glial cells, or broken down by specific enzymes in the synaptic cleft. Numerous Na+-dependent neurotransmitter carrier proteins recycle the neurotransmitters and enable the cells to maintain rapid rates of release.
At chemical synapses, transmitter-gated ion channels play a vital role in rapidly converting extracellular chemical impulses into electrical signals. These channels are located in the postsynaptic cells plasma membrane at the synapse region, and they temporarily open in response to neurotransmitter molecule binding, causing a momentary alteration in the membranes permeability. Additionally, transmitter-gated channels are comparatively less sensitive to the membrane potential than voltage-gated channels, which is why they are unable to generate self-amplifying excitement on their own. However, they result in graded variations in membrane potential due to local permeability, influenced by the amount and duration of neurotransmitter released at the synapse.
Recently, mechanical tension, a phenomenon never thought relevant to synapse function has been found to be required for those on hippocampal neurons to fire. | 1 | Applied and Interdisciplinary Chemistry |
Superfluidity is the characteristic property of a fluid with zero viscosity which therefore flows without any loss of kinetic energy. When stirred, a superfluid forms vortices that continue to rotate indefinitely. Superfluidity occurs in two isotopes of helium (helium-3 and helium-4) when they are liquefied by cooling to cryogenic temperatures. It is also a property of various other exotic states of matter theorized to exist in astrophysics, high-energy physics, and theories of quantum gravity. The theory of superfluidity was developed by Soviet theoretical physicists Lev Landau and Isaak Khalatnikov.
Superfluidity often co-occurs with Bose–Einstein condensation, but neither phenomenon is directly related to the other; not all Bose–Einstein condensates can be regarded as superfluids, and not all superfluids are Bose–Einstein condensates. Superfluids have some potential practical uses, such as dissolving substances in a quantum solvent. | 0 | Theoretical and Fundamental Chemistry |
When several species are compared, similarity values allow organisms to be arranged in a phylogenetic tree; it is therefore one possible approach to carrying out molecular systematics. | 1 | Applied and Interdisciplinary Chemistry |
Radon has been produced commercially for use in radiation therapy, but for the most part has been replaced by radionuclides made in particle accelerators and nuclear reactors. Radon has been used in implantable seeds, made of gold or glass, primarily used to treat cancers.
The gold seeds were produced by filling a long tube with radon pumped from a radium source, the tube being then divided into short sections by crimping and cutting. The gold layer keeps the radon within, and filters out the alpha and beta radiation, while allowing the gamma rays to escape (which kill the diseased tissue). The activities might range from 2 to 200 MBq/seed. The gamma rays are produced by radon and the first short-lived elements of its decay chain (Po, Pb, Bi, Po).
Radon and its first decay products being very short-lived, the seed is left in place. After 11 half-lives (42 days), radon radioactivity is at 1/2 000 of its original level. At this stage, the predominant residual activity is due to the radon decay product Pb, whose half-life (22.3 years) is 2 000 times that of radon, and its descendants Bi and Po, totalling 0.03% of the initial seed activity. | 1 | Applied and Interdisciplinary Chemistry |
In organic chemistry, an alkyl group is an alkane missing one hydrogen.
The term alkyl is intentionally unspecific to include many possible substitutions.
An acyclic alkyl has the general formula of . A cycloalkyl group is derived from a cycloalkane by removal of a hydrogen atom from a ring and has the general formula .
Typically an alkyl is a part of a larger molecule. In structural formulae, the symbol R is used to designate a generic (unspecified) alkyl group. The smallest alkyl group is methyl, with the formula . | 0 | Theoretical and Fundamental Chemistry |
Transcriptional initiation, termination and regulation are mediated by “DNA looping” which brings together promoters, enhancers, transcription factors and RNA processing factors to accurately regulate gene expression. Chromosome conformation capture (3C) and more recently Hi-C techniques provided evidence that active chromatin regions are “compacted” in nuclear domains or bodies where transcriptional regulation is enhanced. The configuration of the genome is essential for enhancer-promoter proximity. Cell-fate decisions are mediated upon highly dynamic genomic reorganizations at interphase to modularly switch on or off entire gene regulatory networks through short to long range chromatin rearrangements. Related studies demonstrate that metazoan genomes are partitioned in structural and functional units around a megabase long called Topological association domains (TADs) containing dozens of genes regulated by hundreds of enhancers distributed within large genomic regions containing only non-coding sequences. The function of TADs is to regroup enhancers and promoters interacting together within a single large functional domain instead of having them spread in different TADs. However, studies of mouse development point out that two adjacent TADs may regulate the same gene cluster. The most relevant study on limb evolution shows that the TAD at the 5’ of the HoxD gene cluster in tetrapod genomes drives its expression in the distal limb bud embryos, giving rise to the hand, while the one located at 3’ side does it in the proximal limb bud, giving rise to the arm. Still, it is not known whether TADs are an adaptive strategy to enhance regulatory interactions or an effect of the constrains on these same interactions.
TAD boundaries are often composed by housekeeping genes, tRNAs, other highly expressed sequences and Short Interspersed Elements (SINE). While these genes may take advantage of their border position to be ubiquitously expressed, they are not directly linked with TAD edge formation. The specific molecules identified at boundaries of TADs are called insulators or architectural proteins because they not only block enhancer leaky expression but also ensure an accurate compartmentalization of cis-regulatory inputs to the targeted promoter. These insulators are DNA-binding proteins like CTCF and TFIIIC that help recruiting structural partners such as cohesins and condensins. The localization and binding of architectural proteins to their corresponding binding sites is regulated by post-translational modifications. DNA binding motifs recognized by architectural proteins are either of high occupancy and at around a megabase of each other or of low occupancy and inside TADs. High occupancy sites are usually conserved and static while intra-TADs sites are dynamic according to the state of the cell therefore TADs themselves are compartmentalized in subdomains that can be called subTADs from few kb up to a TAD long (19). When architectural binding sites are at less than 100 kb from each other, Mediator proteins are the architectural proteins cooperate with cohesin. For subTADs larger than 100 kb and TAD boundaries, CTCF is the typical insulator found to interact with cohesion. | 1 | Applied and Interdisciplinary Chemistry |
Foldit is an online puzzle video game about protein folding. It is part of an experimental research project developed by the University of Washington, Center for Game Science, in collaboration with the UW Department of Biochemistry. The objective of Foldit is to fold the structures of selected proteins as perfectly as possible, using tools provided in the game. The highest scoring solutions are analyzed by researchers, who determine whether or not there is a native structural configuration (native state) that can be applied to relevant proteins in the real world. Scientists can then use these solutions to target and eradicate diseases and create biological innovations. A 2010 paper in the science journal Nature credited Foldit's 57,000 players with providing useful results that matched or outperformed algorithmically computed solutions. | 1 | Applied and Interdisciplinary Chemistry |
Double-stranded DNA is sheared using one of these methods: sonication, enzymatic digestion, or nebulization. Fragments are size selected using Ampure XP beads. Gel-based size selection is not recommended since it can cause melting of DNA double strands and DNA damage due to UV exposure. The size of selected fragments of DNA are subjected to 3’-end-dA-tailing. | 1 | Applied and Interdisciplinary Chemistry |
Gram-negative bacteria produce N-acyl homoserine lactones (AHL) as their signaling molecule. Usually AHLs do not need additional processing, and bind directly to transcription factors to regulate gene expression.
Some gram-negative bacteria may use the two-component system as well. | 1 | Applied and Interdisciplinary Chemistry |
The objective of acoustic foam is to enhance the sonic properties of a room by effectively managing unwanted reverberations. For this reason, acoustic foam is often used in restaurants, performance spaces, and recording studios. Acoustic foam is also often installed in large rooms with large, reverberative surfaces like gymnasiums, churches, synagogues, theaters, and concert halls where excess reverberation is prone to arise. The purpose is to reduce, but not entirely eliminate, resonance within the room. In unmanaged spaces without acoustic foam or similar sound absorbing materials, sound waves reflect off of surfaces and continue to bounce around in the room. When a wave encounters a change in acoustic impedance, such as hitting a solid surface, acoustic reflections transpire. These reflections will occur many times before the wave becomes inaudible. Reflections can cause acoustic problems such as phase summation and phase cancellation. A new complex wave originates when the direct source wave coincides with the reflected waves. This complex wave will change the frequency response of the source material. | 0 | Theoretical and Fundamental Chemistry |
The Batchelor vortex is an approximate solution to the Navier–Stokes equations obtained using a boundary layer approximation. The physical reasoning behind this approximation is the assumption that the axial gradient of the flow field of interest is of much smaller magnitude than the radial gradient.
<br>
The axial, radial and azimuthal velocity components of the vortex are denoted , and respectively and can be represented in cylindrical coordinates as follows:<br>
The parameters in the above equations are
* , the free-stream axial velocity,
* , the velocity scale (used for nondimensionalization),
* , the length scale (used for nondimensionalization),
* , a measure of the core size, with initial core size and representing viscosity,
* , the swirl strength, given as a ratio between the maximum tangential velocity and the core velocity.
<br>
Note that the radial component of the velocity is zero and that the axial and azimuthal components depend only on .
<br>
We now write the system above in dimensionless form by scaling time by a factor . Using the same symbols for the dimensionless variables, the Batchelor vortex can be expressed in terms of the dimensionless variables as
<br>
where denotes the free stream axial velocity and is the Reynolds number.
If one lets and considers an infinitely large swirl number then the Batchelor vortex simplifies to the Lamb–Oseen vortex for the azimuthal velocity:
where is the circulation. | 1 | Applied and Interdisciplinary Chemistry |
TTFB (4,5,6,7-Tetrachloro-2-trifluoromethylbenzimidazole) is a halogenated benzimidazole derivative that acts as an uncoupling agent. | 1 | Applied and Interdisciplinary Chemistry |
The regulation of Ler and its transcript, ler, is complex and many-fold. The plasmid encoded regulator (per) directly activates the region of the LEE1 operon which encodes Ler. Integration host factor is also a direct activator of ler and binds upstream of its promoter.
Jeannette Barba and her colleagues at the National Autonomous University of Mexico elucidated a positive regulatory loop between Ler, ler, GrlA, and grlRA. GrlA is also a LEE encoded regulator of the LEE pathogenicity island. They found that GrlA activates ler, and that Ler activates grlRA indicating a loop of activation wherein a protein product activates a transcript whose protein product activates the transcript of the original protein. Ler activates grlRA only if H-NS is present, this is not the case for GrlA activation of ler.
Quorum sensing plays a role in Ler regulation. LuxS is an important protein involved in quorum sensing, particularly in the synthesis of autoinducer molecules. Quorum-sensing E. coli regulator A (QseA) is found in LuxS systems and activates transcription of ler. Fis, a nucleoid associated protein essential for EPEC's ability to form attaching and effacing lesions, partly acts through activation of Ler expression. BipA, a ribosomal binding GTPase and prolific regulator of EPEC virulence, transcriptionally regulates Ler from an upstream position where it also regulates other genes.
The Ler protein also represses its own transcript on the LEE1 operon through DNA looping which prevents RNA polymerase from completing transcription. | 1 | Applied and Interdisciplinary Chemistry |
Some examples of macromolecules are synthetic polymers (plastics, synthetic fibers, and synthetic rubber), graphene, and carbon nanotubes. Polymers may be prepared from inorganic matter as well as for instance in inorganic polymers and geopolymers. The incorporation of inorganic elements enables the tunability of properties and/or responsive behavior as for instance in smart inorganic polymers. | 0 | Theoretical and Fundamental Chemistry |
In biochemistry, equilibrium unfolding is the process of unfolding a protein or RNA molecule by gradually changing its environment, such as by changing the temperature or pressure, pH, adding chemical denaturants, or applying force as with an atomic force microscope tip. If the equilibrium was maintained at all steps, the process theoretically should be reversible during equilibrium folding. Equilibrium unfolding can be used to determine the thermodynamic stability of the protein or RNA structure, i.e. free energy difference between the folded and unfolded states. | 0 | Theoretical and Fundamental Chemistry |
The Key Centre for Polymers and Colloids (KCPC) is a research centre of the School of Chemistry established by the Australian Research Council Research Centres Program. While the KCPC is known for polymers and colloids, it comprises several groups that can specialise in different areas like self-assembly, virus mimics, emulsions, and surfactants. The KCPC has attracted various industry support such as Orica, Nuplex Industries, and others. Currently, faculty members involved in KCPC research are: A/Prof. Brian Hawkett, A/Prof. Chiara Neto, Dr. Mohammad Choucair, Prof. Greg Warr, Dr. Markus Muellner, and E/Prof. Les Copeland.
The current KCPC Director is A/Prof. Brian Hawkett. | 1 | Applied and Interdisciplinary Chemistry |
A supersonic wind tunnel is a wind tunnel that produces supersonic speeds (1.2<M<5)
The Mach number and flow are determined by the nozzle geometry. The Reynolds number is varied by changing the density level (pressure in the settling chamber). Therefore, a high pressure ratio is required (for a supersonic regime at M=4, this ratio is of the order of 10). Apart from that, condensation of moisture or even gas liquefaction can occur if the static temperature becomes cold enough. This means that a supersonic wind tunnel usually needs a drying or a pre-heating facility.
A supersonic wind tunnel has a large power demand, so most are designed for intermittent instead of continuous operation.
The first supersonic wind tunnel (with a cross section of 2 cm) was built in National Physical Laboratory in England, and started working in 1922. | 1 | Applied and Interdisciplinary Chemistry |
First Example: Let gas 1 be H and gas 2 be O. (This example is solving for the ratio between the rates of the two gases)
Therefore, hydrogen molecules effuse four times faster than those of oxygen.
Graham's Law can also be used to find the approximate molecular weight of a gas if one gas is a known species, and if there is a specific ratio between the rates of two gases (such as in the previous example). The equation can be solved for the unknown molecular weight.
Graham's law was the basis for separating uranium-235 from uranium-238 found in natural uraninite (uranium ore) during the Manhattan Project to build the first atomic bomb. The United States government built a gaseous diffusion plant at the Clinton Engineer Works in Oak Ridge, Tennessee, at the cost of $479 million (equivalent to $ in ). In this plant, uranium from uranium ore was first converted to uranium hexafluoride and then forced repeatedly to diffuse through porous barriers, each time becoming a little more enriched in the slightly lighter uranium-235 isotope.
Second Example: An unknown gas diffuses 0.25 times as fast as He. What is the molar mass of the unknown gas?
Using the formula of gaseous diffusion, we can set up this equation.
Which is the same as the following because the problem states that the rate of diffusion of the unknown gas relative to the helium gas is 0.25.
Rearranging the equation results in | 0 | Theoretical and Fundamental Chemistry |
Within mathematics, inexact differentials are usually just referred more generally to as differential forms which are often written just as . | 0 | Theoretical and Fundamental Chemistry |
If the disturbances to the steady planar flame sheet are of the form , where is the transverse coordinate system that lies on the undisturbed stationary flame sheet, is the time, is the wavevector of the disturbance and is the temporal growth rate of the disturbance, then the dispersion relation is given by
where is the laminar burning velocity (or, the flow velocity far upstream of the flame in a frame that is fixed to the flame), and is the ratio of unburnt to burnt gas density. In combustion always and therefore the growth rate for all wavenumbers. This implies that a plane sheet of flame with a burning velocity is unstable for all wavenumbers. In fact, Amable Liñán and Forman A. Williams quote in their book that in view of laboratory observations of stable, planar, laminar flames, publication of their theoretical predictions required courage on the part of Darrieus and Landau.
If the buoyancy forces are taken into account (in others words, accounts of Rayleigh–Taylor instability are considered) for planar flames that are perpendicular to the gravity vector, then some level of stability can be anticipated for flames propagating vertically downwards (or flames that held stationary by a vertically upward flow) since in these cases, the denser unburnt gas lies beneath the lighter burnt gas mixture. Of course, flames that are propagating vertically upwards or those that are held stationary by a vertically downward flow, both the Darrieus–Landau mechanism and the Rayleigh–Taylor mechanism contributes to the destabilizing effect. The dispersion relation when buoyance forces are included becomes
where corresponds to gravitational acceleration for flames propagating downwards and corresponds to gravitational acceleration for flames propagating upwards. The above dispersion implies that gravity introduces stability for downward propagating flames when , where is a characteristic buoyancy length scale.
Darrieus and Landau's analysis treats the flame as a plane sheet to investigate its stability with the neglect of diffusion effects, whereas in reality, the flame has a definite thickness, say the laminar flame thickness , where is the thermal diffusivity, wherein diffusion effects cannot be neglected. Accounting for the flame structure, are found to stabilize the flames for small wavelengths , except when fuel diffusion coefficient and thermal diffusivity differ from each other significantly leading to the so-called (Turing) diffusive-thermal instability.
Darrieus–Landau instability manifests in the range for downward propagating flames and for upward propagating flames. | 1 | Applied and Interdisciplinary Chemistry |
SK3 (small conductance calcium-activated potassium channel 3) also known as K2.3 is a protein that in humans is encoded by the KCNN3 gene.
SK3 is a small-conductance calcium-activated potassium channel partly responsible for the calcium-dependent after hyperpolarisation current (I). It belongs to a family of channels known as small-conductance potassium channels, which consists of three members – SK1, SK2 and SK3 (encoded by the KCNN1, 2 and 3 genes respectively), which share a 60-70% sequence identity. These channels have acquired a number of alternative names, however a NC-IUPHAR has recently achieved consensus on the best names, K2.1 (SK1), K2.2 (SK2) and K2.3 (SK3). Small conductance channels are responsible for the medium and possibly the slow components of the I. | 1 | Applied and Interdisciplinary Chemistry |
*Hollow tube dispensers are plastic twist-tie type dispensers, plastic hollow fibers or plastic hollow microfibers fibers, filled with synthetic sex pheromone and placed throughout the area to be protected.
*Pheromone Baits and Stations are a stationary, attract and kill type of dispensers. Some are relatively large platform, containing a pheromone lure inside a glue board that ensnares the attracted insect. Other pheromone bait stations contain a pheromone lure in conjunction with a surface containing a dose of insecticide that reduces the attracted insect's fitness, thus reducing its ability to mate and reproduce.
*High-emission dispensers There are several very high dose pheromone dispensers, some do it passively, like pheromone sachets and large dollops of SPLAT pheromone formulations, others do it be actively releasing bursts of sex pheromone at timed intervals. | 1 | Applied and Interdisciplinary Chemistry |
Moroidin is a biologically active compound found in the plants Dendrocnide moroides and Celosia argentea. It is a peptide composed of eight amino acids, with unusual leucine-tryptophan and tryptophan-histidine cross-links that form its two rings. Moroidin has been shown to be at least one of several bioactive compounds responsible for the painful sting of the Dendrocnide moroides plant. It also has demonstrated anti-mitotic properties, specifically by inhibition of tubulin polymerization. Anti-mitotic activity gives moroidin potential as a chemotherapy drug, and this property combined with its unusual chemical structure has made it a target for organic synthesis. | 0 | Theoretical and Fundamental Chemistry |
Particles can be electrically charged or uncharged:
Particle radiation can be emitted by an unstable atomic nucleus (via radioactive decay), or it can be produced from some other kind of nuclear reaction. Many types of particles may be emitted:
*protons and other hydrogen nuclei stripped of their electrons
*positively charged alpha particles (α), equivalent to a helium-4 nucleus
*helium ions at high energy levels
*HZE ions, which are nuclei heavier than helium
*positively or negatively charged beta particles (high-energy positrons β or electrons β; the latter being more common)
*high-speed electrons that are not from the beta decay process, but others such as internal conversion and Auger effect
*neutrons, subatomic particles which have no charge; neutron radiation
*neutrinos
*mesons
*muons
Mechanisms that produce particle radiation include:
*alpha decay
*Auger effect
*beta decay
*cluster decay
*internal conversion
*neutron emission
*nuclear fission and spontaneous fission
*nuclear fusion
*particle colliders in which streams of high energy particles are smashed
*proton emission
*solar flares
*solar particle events
*supernova explosions
*Additionally, galactic cosmic rays include these particles, but many are from unknown mechanisms
Charged particles (electrons, mesons, protons, alpha particles, heavier HZE ions, etc.) can be produced by particle accelerators. Ion irradiation is widely used in the semiconductor industry to introduce dopants into
materials, a method known as ion implantation.
Particle accelerators can also produce neutrino beams. Neutron beams are mostly produced by nuclear reactors. | 0 | Theoretical and Fundamental Chemistry |
The type II receptors phosphorylate the type I receptors; the type I receptors are then enabled to phosphorylate cytoplasmic R-Smads, which then act as transcriptional regulators. Signaling is initiated by the binding of TGF-β to its serine/threonine receptors. The serene/threonine receptors are the type II and type I receptors on the cell membrane. Binding of a TGF-β members induces assembly of a heterotetrameric complex of two type I and two type II receptors at the plasma membrane. Individual members of the TGF-β family bind to a certain set of characteristic combination of these type I and type II receptors. The type I receptors can be divided into two groups, which depends on the cytoplasmic R-Smads that they bind and phosphorylate. The first group of type I receptors (Alk1/2/3/6) bind and activate the R-Smads, Smad1/5/8. The second group of type I reactors (Alk4/5/7) act on the R-Smads, Smad2/3. The phosphorylated R-Smads then form complexes and the signals are funneled through two regulatory Smad (R-Smad) channels (Smad1/5/8 or Smad2/3). After the ligand-receptor complexes phosphorylate the cytoplasmic R-Smads, the signal is then sent through Smad 1/5/8 or Smad 2/3. This leads to the downstream signal cascade and cellular gene targeting. | 1 | Applied and Interdisciplinary Chemistry |
Bacteriological water analysis is a method of analysing water to estimate the numbers of bacteria present and, if needed, to find out what sort of bacteria they are. It represents one aspect of water quality. It is a microbiological analytical procedure which uses samples of water and from these samples determines the concentration of bacteria. It is then possible to draw inferences about the suitability of the water for use from these concentrations. This process is used, for example, to routinely confirm that water is safe for human consumption or that bathing and recreational waters are safe to use.
The interpretation and the action trigger levels for different waters vary depending on the use made of the water. Whilst very stringent levels apply to drinking water, more relaxed levels apply to marine bathing waters, where much lower volumes of water are expected to be ingested by users. | 0 | Theoretical and Fundamental Chemistry |
Laser Doppler velocimetry is used in hemodynamics research as a technique to partially quantify blood flow in human tissues such as skin or the eye fundus. Within the clinical environment, the technology is often referred to as laser Doppler flowmetry; when images are made, it is referred to as laser Doppler imaging. The beam from a low-power laser (usually a laser diode) penetrates the skin sufficiently to be scattered with a Doppler shift by the red blood cells and return to be concentrated on a detector. These measurements are useful to monitor the effect of exercise, drug treatments, environmental, or physical manipulations on targeted micro-sized vascular areas.
The laser Doppler vibrometer is being used in clinical otology for the measurement of tympanic membrane (eardrum), malleus (hammer), and prosthesis head displacement in response to sound inputs of 80- to 100-dB sound-pressure level. It also has potential use in the operating room to perform measurements of prosthesis and stapes (stirrup) displacement. | 1 | Applied and Interdisciplinary Chemistry |
Trimethylenemethane cycloaddition is the formal (3+2) annulation of trimethylenemethane (TMM) derivatives to two-atom pi systems. Although TMM itself is too reactive and unstable to be stored, reagents which can generate TMM or TMM synthons in situ can be used to effect cycloaddition reactions with appropriate electron acceptors. Generally, electron-deficient pi bonds undergo cyclization with TMMs more easily than electron-rich pi bonds. | 0 | Theoretical and Fundamental Chemistry |
The slides are then immersed in a solution that cause the cells to lyse. The lysis solution often used in the comet assay consists of a highly concentrated aqueous salt (often, common table salt can be used) and a detergent (such as Triton X-100 or sarcosinate). The pH of the lysis solution can be adjusted (usually between neutral and alkaline pH) depending upon the type of damage the researcher is investigating.
The aqueous salt disrupts proteins and their bonding patterns within the cell as well as disrupting the RNA content of the cell. The detergent dissolves the cellular membranes. Through the action of the lysis solution the cells are destroyed. All proteins, RNA, membranes and cytoplasmic and nucleoplasmic constituents are disrupted and diffuse into the agarose matrix. Only the DNA of the cell remains, and unravels to fill the cavity in the agarose that the whole cell formerly filled. This structure is called nucleoid (a general term for a structure in which DNA is concentrated). | 1 | Applied and Interdisciplinary Chemistry |
Charge exchange (or charge exchange collision) is a process in which a neutral atom or molecule collides with an ion, resulting in the neutral atom acquiring the charge of the ion. The reaction is typically expressed as
This reaction has various diagnostic applications, such as in plasma physics and mass spectrometry. | 0 | Theoretical and Fundamental Chemistry |
DNA-dependent ATPase, abbreviated Dda and also known as Dda helicase and Dda DNA helicase, is the 439-amino acid 49,897-atomic mass unit protein coded by the Dda gene of the bacteriophage T4 phage, a virus that infects enterobacteria. | 1 | Applied and Interdisciplinary Chemistry |
Biological oxidation of organic matters has led to the innovation of a low cost secondary treatment of the waste water emissions and industrial air emissions. The process of biodegradation offers a very fast method which typically offers 4,000 catalytic cycles per minute. Destruction rate efficiency is generally greater than 99% on most biodegradable organics emissions. The biological oxidation technology is free from secondary emissions () with limited production. While other oxidation technologies such as thermal oxidation produces CO, NO and CO. | 1 | Applied and Interdisciplinary Chemistry |
Stills
*Alembic
*Retort
**Retort stand
Vessels
*Aludel
*Crucible
**Hessian crucible
*Cupels
*Mortar and pestle
Heating devices
*Athanor
*Bain-marie
*Sand bath | 1 | Applied and Interdisciplinary Chemistry |
Several formulas are used to calculate T values. Some formulas are more accurate in predicting melting temperatures of DNA duplexes. For DNA oligonucleotides, i.e. short sequences of DNA, the thermodynamics of hybridization can be accurately described as a two-state process. In this approximation one neglects the possibility of intermediate partial binding states in the formation of a double strand state from two single stranded oligonucleotides. Under this assumption one can elegantly describe the thermodynamic parameters for forming double-stranded nucleic acid AB from single-stranded nucleic acids A and B.
:AB ↔ A + B
The equilibrium constant for this reaction is . According to the Van´t Hoff equation, the relation between free energy, ΔG, and K is ΔG° = -RTln K, where R is the ideal gas law constant, and T is the kelvin temperature of the reaction. This gives, for the nucleic acid system,
The melting temperature, T, occurs when half of the double-stranded nucleic acid has dissociated. If no additional nucleic acids are present, then [A], [B], and [AB] will be equal, and equal to half the initial concentration of double-stranded nucleic acid, [AB]. This gives an expression for the melting point of a nucleic acid duplex of
Because ΔG° = ΔH° -TΔS°, T is also given by
The terms ΔH° and ΔS° are usually given for the association and not the dissociation reaction (see the nearest-neighbor method for example). This formula then turns into:
, where [B] ≤ [A].
As mentioned, this equation is based on the assumption that only two states are involved in melting: the double stranded state and the random-coil state. However, nucleic acids may melt via several intermediate states. To account for such complicated behavior, the methods of statistical mechanics must be used, which is especially relevant for long sequences. | 1 | Applied and Interdisciplinary Chemistry |
Transport of material in stagnant fluid or across streamlines of a fluid in a laminar flow occurs by molecular diffusion. Two adjacent compartments separated by a partition, containing pure gases A or B may be envisaged. Random movement of all molecules occurs so that after a period molecules are found remote from their original positions. If the partition is removed, some molecules of A move towards the region occupied by B, their number depends on the number of molecules at the region considered. Concurrently, molecules of B diffuse toward regimens formerly occupied by pure A.
Finally, complete mixing occurs. Before this point in time, a gradual variation in the concentration of A occurs along an axis, designated x, which joins the original compartments. This variation, expressed mathematically as -dC/dx, where C is the concentration of A. The negative sign arises because the concentration of A decreases as the distance x increases. Similarly, the variation in the concentration of gas B is -dC/dx. The rate of diffusion of A, N, depend on concentration gradient and the average velocity with which the molecules of A moves in the x direction. This relationship is expressed by Fick's Law
: (only applicable for no bulk motion)
where D is the diffusivity of A through B, proportional to the average molecular velocity and, therefore dependent on the temperature and pressure of gases. The rate of diffusion N, is usually expressed as the number of moles diffusing across unit area in unit time. As with the basic equation of heat transfer, this indicates that the rate of force is directly proportional to the driving force, which is the concentration gradient.
This basic equation applies to a number of situations. Restricting discussion exclusively to steady state conditions, in which neither dC/dx or dC/dx change with time, equimolecular counterdiffusion is considered first. | 1 | Applied and Interdisciplinary Chemistry |
In the four tables below, the minor branches of decay (with the branching probability of less than 0.0001%) are omitted. The energy release includes the total kinetic energy of all the emitted particles (electrons, alpha particles, gamma quanta, neutrinos, Auger electrons and X-rays) and the recoil nucleus, assuming that the original nucleus was at rest. The letter a represents a year (from the Latin annus).
In the tables below (except neptunium), the historic names of the naturally occurring nuclides are also given. These names were used at the time when the decay chains were first discovered and investigated. From these historical names one can locate the particular chain to which the nuclide belongs, and replace it with its modern name.
The three naturally-occurring actinide alpha decay chains given below—thorium, uranium/radium (from uranium-238), and actinium (from uranium-235)—each ends with its own specific lead isotope (lead-208, lead-206, and lead-207 respectively). All these isotopes are stable and are also present in nature as primordial nuclides, but their excess amounts in comparison with lead-204 (which has only a primordial origin) can be used in the technique of uranium–lead dating to date rocks. | 0 | Theoretical and Fundamental Chemistry |
In molecular biology, a stop codon (or termination codon) is a codon (nucleotide triplet within messenger RNA) that signals the termination of the translation process of the current protein. Most codons in messenger RNA correspond to the addition of an amino acid to a growing polypeptide chain, which may ultimately become a protein; stop codons signal the termination of this process by binding release factors, which cause the ribosomal subunits to disassociate, releasing the amino acid chain.
While start codons need nearby sequences or initiation factors to start translation, a stop codon alone is sufficient to initiate termination. | 1 | Applied and Interdisciplinary Chemistry |
Sustainable crop production is becoming increasingly important, if humans are to support a growing population and avoid a collapse of production systems. While the understanding and incorporation of tritrophic interactions in pest control offers a promising control option, the sustainable biological control of pests requires a dynamic approach that involves diversity in all of the species present, richness in natural enemies, and limited adverse activity (i.e., minimal pesticide use). This approach is especially important in conservation biological control efforts.
There are typically more than three trophic levels at play in a given production setting, so the tritrophic interaction model may represent an oversimplification. Furthermore, ecological complexity and interactions between species of the same trophic level can come into play. Research thus far has had a relatively narrow focus, which may be suitable for controlled environments such as greenhouses but which has not yet addressed multi-generational plant interactions with dynamic communities of organisms. | 1 | Applied and Interdisciplinary Chemistry |
A turbidity current is most typically an underwater current of usually rapidly moving, sediment-laden water moving down a slope; although current research (2018) indicates that water-saturated sediment may be the primary actor in the process. Turbidity currents can also occur in other fluids besides water.
Researchers from the Monterey Bay Aquarium Research Institute found that a layer of water-saturated sediment moved rapidly over the seafloor and mobilized the upper few meters of the preexisting seafloor. Plumes of sediment-laden water were observed during turbidity current events but they believe that these were secondary to the pulse of the seafloor sediment moving during the events. The belief of the researchers is that the water flow is the tail-end of the process that starts at the seafloor.
In the most typical case of oceanic turbidity currents, sediment laden waters situated over sloping ground will flow down-hill because they have a higher density than the adjacent waters. The driving force behind a turbidity current is gravity acting on the high density of the sediments temporarily suspended within a fluid. These semi-suspended solids make the average density of the sediment bearing water greater than that of the surrounding, undisturbed water.
As such currents flow, they often have a "snow-balling-effect", as they stir up the ground over which they flow, and gather even more sedimentary particles in their current. Their passage leaves the ground over which they flow scoured and eroded. Once an oceanic turbidity current reaches the calmer waters of the flatter area of the abyssal plain (main oceanic floor), the particles borne by the current settle out of the water column. The sedimentary deposit of a turbidity current is called a turbidite.
Seafloor turbidity currents are often the result of sediment-laden river outflows, and can sometimes be initiated by earthquakes, slumping and other soil disturbances. They are characterized by a well-defined advance-front, also known as the currents head, and are followed by the currents main body. In terms of the more often observed and more familiar above sea-level phenomenon, they somewhat resemble flash floods.
Turbidity currents can sometimes result from submarine seismic instability, which is common with steep underwater slopes, and especially with submarine trench slopes of convergent plate margins, continental slopes and submarine canyons of passive margins. With an increasing continental shelf slope, current velocity increases, as the velocity of the flow increases, turbulence increases, and the current draws up more sediment. The increase in sediment also adds to the density of the current, and thus increases its velocity even further. | 1 | Applied and Interdisciplinary Chemistry |
When a plant or animal dies or an animal expels waste, the initial form of nitrogen is organic. Bacteria or fungi convert the organic nitrogen within the remains back into ammonium (), a process called ammonification or mineralization. Enzymes involved are:
* GS: Gln Synthetase (cytosolic & plastic)
* GOGAT: Glu 2-oxoglutarate aminotransferase (Ferredoxin & NADH-dependent)
* GDH: Glu Dehydrogenase:
** Minor role in ammonium assimilation.
** Important in amino acid catabolism. | 1 | Applied and Interdisciplinary Chemistry |
The genomes of Melainabacteria organisms isolated from ground water indicate that the organism has the capacity to fix nitrogen. Melainabacteria lack linked electron transport chains but have multiple methods to generate a membrane potential which can then produce ATP via ATP synthase. They are able to use Fe hydrogenases for production that can be consumed by other microorganisms. Melainabacteria from the human gut also synthesize several B and K vitamins, which suggests that these bacteria are beneficial to their host because they are consumed along with plant fibers. | 1 | Applied and Interdisciplinary Chemistry |
An important occurrence of phosphates in biological systems is as the structural material of bone and teeth. These structures are made of crystalline calcium phosphate in the form of hydroxyapatite. The hard dense enamel of mammalian teeth may contain fluoroapatite, a hydroxy calcium phosphate where some of the hydroxyl groups have been replaced by fluoride ions. | 0 | Theoretical and Fundamental Chemistry |
An expression vector must have elements necessary for gene expression. These may include a promoter, the correct translation initiation sequence such as a ribosomal binding site and start codon, a termination codon, and a transcription termination sequence. There are differences in the machinery for protein synthesis between prokaryotes and eukaryotes, therefore the expression vectors must have the elements for expression that are appropriate for the chosen host. For example, prokaryotes expression vectors would have a Shine-Dalgarno sequence at its translation initiation site for the binding of ribosomes, while eukaryotes expression vectors would contain the Kozak consensus sequence.
The promoter initiates the transcription and is therefore the point of control for the expression of the cloned gene. The promoters used in expression vector are normally inducible, meaning that protein synthesis is only initiated when required by the introduction of an inducer such as IPTG. Gene expression however may also be constitutive (i.e. protein is constantly expressed) in some expression vectors. Low level of constitutive protein synthesis may occur even in expression vectors with tightly controlled promoters. | 1 | Applied and Interdisciplinary Chemistry |
The ratio average (RA) plot is an integer-based version of an MA plot for visualizing two-condition count data. Its distinctive arrow-like shape derives from the way it includes condition-unique (0,n) or (n,0) points into the plot via an epsilon factor. | 1 | Applied and Interdisciplinary Chemistry |
From studies and predictions such as Dreyer and Bennett's, it shows that the light chains and heavy chains are encoded by separate multigene families on different chromosomes. They are referred to as gene segments and are separated by non-coding regions. The rearrangement and organization of these gene segments during the maturation of B cells produce functional proteins. The entire process of rearrangement and organization of these gene segments is the vital source where our body immune system gets its capabilities to recognize and respond to variety of antigens. | 1 | Applied and Interdisciplinary Chemistry |
The binding constant is a special case of the equilibrium constant . It is associated with the binding and unbinding reaction of receptor (R) and ligand (L) molecules, which is formalized as:
The reaction is characterized by the on-rate constant and the off-rate constant , which have units of 1/(concentration time) and 1/time, respectively. In equilibrium, the forward binding transition should be balanced by the backward unbinding transition . That is,
where , and represent the concentration of unbound free receptors, the concentration of unbound free ligand and the concentration of receptor-ligand complexes. The binding constant, or the association constant is defined by | 0 | Theoretical and Fundamental Chemistry |
In the history of gunpowder there are a range of theories about the transmission of the knowledge of gunpowder and guns from Imperial China to the rest of the world following the Song, Jin and Yuan dynasties. The earliest bronze guns found in China date back to the 13th century, with archaeological and textual evidence for previous nascent gunpowder technology developed beforehand. Scholars note the scarcity of records for firearms in the Middle East prior to the mid-14th century, and in Russia before the late 14th century, yet cannons already appeared in Europe by the early 14th century. Less accepted theories include gunpowder as being independently invented in the Middle East or South Asia. | 1 | Applied and Interdisciplinary Chemistry |
Downregulation of protein kinase A occurs by a feedback mechanism and uses a number of cAMP hydrolyzing phosphodiesterase (PDE) enzymes, which belong to the substrates activated by PKA. Phosphodiesterase quickly converts cAMP to AMP, thus reducing the amount of cAMP that can activate protein kinase A. PKA is also regulated by a complex series of phosphorylation events, which can include modification by autophosphorylation and phosphorylation by regulatory kinases, such as PDK1.
Thus, PKA is controlled, in part, by the levels of cAMP. Also, the catalytic subunit itself can be down-regulated by phosphorylation. | 1 | Applied and Interdisciplinary Chemistry |
The multidisciplinary approach in Environmental Engineering Science gives the student expertise in technical fields related to their own personal interest. While some graduates choose to use this major to go to graduate school, students who choose to work often go into the fields of civil and environmental engineering, biotechnology, and research. However, the less technical math, programming and writing background gives the students opportunities to pursue IT work and technical writing. | 1 | Applied and Interdisciplinary Chemistry |
Since the start of the Industrial Revolution, atmospheric concentration have been increasing, causing global warming and ocean acidification. In October 2023 the average level of in Earth's atmosphere, adjusted for seasonal variation, was 422.17 parts per million by volume (ppm). Figures are published monthly by the National Oceanic & Atmospheric Administration (NOAA). The value had been about 280 ppm during the 10,000 years up to the mid-18th century.
Each part per million of in the atmosphere represents approximately 2.13 gigatonnes of carbon, or 7.82 gigatonnes of .
It was pointed out in 2021 that "the current rates of increase of the concentration of the major greenhouse gases (carbon dioxide, methane and nitrous oxide) are unprecedented over at least the last 800,000 years".
It has been estimated that 2,400 gigatons of CO₂ have been emitted by human activity since 1850, with some absorbed by oceans and land, and about 950 gigatons remaining in the atmosphere. Around 2020 the emission rate was over 40 gigatons per year.
Some fraction (a projected 20–35%) of the fossil carbon transferred thus far will persist in the atmosphere as elevated levels for many thousands of years after these carbon transfer activities begin to subside. | 1 | Applied and Interdisciplinary Chemistry |
Found within The Chronology of Ancient Kingdoms Amended, are several passages that directly mention the land of Atlantis. The first such passage is part of his Short Chronicle which indicates his belief that Homer's Ulysses left the island of Ogygia in 896 BC. In Greek mythology, Ogygia was home to Calypso, the daughter of Atlas (after whom Atlantis was named). Some scholars have suggested that Ogygia and Atlantis are locationally connected, or possibly the same island. From his writings it appears Newton may have shared this belief. Newton also lists Cadis or Cales as possible candidates for Ogygia, though does not cite his reasons for believing so. | 1 | Applied and Interdisciplinary Chemistry |
She earned her PhD in chemical sciences at the University of Florence in 2004. She was a postdoctoral fellow at the University of Pisa, where she worked on the mechanisms by which metal-complexes that are used as anti-cancer agents activate. She used both spectroscopy, including mass spectrometry imaging, and molecular biology. | 0 | Theoretical and Fundamental Chemistry |
SPR can be used to study the real-time kinetics of molecular interactions. Determining the affinity between two ligands involves establishing the equilibrium dissociation constant, representing the equilibrium value for the product quotient. This constant can be determined using dynamic SPR parameters, calculated as the dissociation rate divided by the association rate.
In this process, a ligand is immobilized on the dextran surface of the SPR crystal. Through a microflow system, a solution with the analyte is injected over the ligand-covered surface. The binding of the analyte to the ligand causes an increase in the SPR signal (expressed in response units, RU). Following the association time, a solution without the analyte (typically a buffer) is introduced into the microfluidics to initiate the dissociation of the bound complex between the ligand and analyte. As the analyte dissociates from the ligand, the SPR signal decreases. From these association (on rate, ) and dissociation rates (off rate, ), the equilibrium dissociation constant (binding constant, ) can be calculated.
The detected SPR signal is a consequence of the electromagnetic coupling of the incident light with the surface plasmon of the gold layer. This interaction is particularly sensitive to the characteristics of the layer at the gold–solution interface, which is usually just a few nanometers thick. When substances bind to the surface, it alters the way light is reflected, causing a change in the reflection angle, which can be measured as a signal in SPR experiments. One common application is measuring the kinetics of antibody-antigen interactions. | 0 | Theoretical and Fundamental Chemistry |
The most important aspect of disulfide bonds is their scission, as the bond is usually the weakest bond in a molecule. Many specialized organic reactions have been developed to cleave the bond.
A variety of reductants reduce disulfides to thiols. Hydride agents are typical reagents, and a common laboratory demonstration "uncooks" eggs with sodium borohydride. Alkali metals effect the same reaction more aggressively: followed by protonation of the resulting metal thiolate:
In biochemistry labwork, thiols such as β-mercaptoethanol (β-ME) or dithiothreitol (DTT) serve as reductants through thiol-disulfide exchange. The thiol reagents are used in excess to drive the equilibrium to the right:
The reductant tris(2-carboxyethyl)phosphine (TCEP) is useful, beside being odorless compared to β-ME and DTT, because it is selective, working at both alkaline and acidic conditions (unlike DTT), is more hydrophilic and more resistant to oxidation in air. Furthermore, it is often not needed to remove TCEP before modification of protein thiols.
In Zincke cleavage, halogens oxidize disulfides to a sulfenyl halide:
More unusually, oxidation of disulfides gives first thiosulfinates and then thiosulfonates:
:RSSR + [O] → RS(=O)SR
:RS(=O)SR + [O] → RS(=O)SR | 0 | Theoretical and Fundamental Chemistry |
The development started with early work on the underlying sensor technology. One of the first portable, chemistry-based sensors was the glass pH electrode, invented in 1922 by Hughes. The basic concept of using exchange sites to create permselective membranes was used to develop other ion sensors in subsequent years. For example, a K sensor was produced by incorporating valinomycin into a thin membrane.
In 1953, Watson and Crick announced their discovery of the now familiar double helix structure of DNA molecules and set the stage for genetics research that continues to the present day. The development of sequencing techniques in 1977 by Gilbert and Sanger (working separately) enabled researchers to directly read the genetic codes that provide instructions for protein synthesis. This research showed how hybridization of complementary single oligonucleotide strands could be used as a basis for DNA sensing. Two additional developments enabled the technology used in modern DNA-based. First, in 1983 Kary Mullis invented the polymerase chain reaction (PCR) technique, a method for amplifying DNA concentrations. This discovery made possible the detection of extremely small quantities of DNA in samples. Secondly in 1986 Hood and co-workers devised a method to label DNA molecules with fluorescent tags instead of radiolabels, thus enabling hybridization experiments to be observed optically.
Figure 1 shows the make up of a typical biochip platform. The actual sensing component (or "chip") is just one piece of a complete analysis system. Transduction must be done to translate the actual sensing event (DNA binding, oxidation/reduction, etc.) into a format understandable by a computer (voltage, light intensity, mass, etc.), which then enables additional analysis and processing to produce a final, human-readable output. The multiple technologies needed to make a successful biochip—from sensing chemistry, to microarraying, to signal processing—require a true multidisciplinary approach, making the barrier to entry steep. One of the first commercial biochips was introduced by Affymetrix. Their "GeneChip" products contain thousands of individual DNA sensors for use in sensing defects, or single nucleotide polymorphisms (SNPs), in genes such as p53 (a tumor suppressor) and BRCA1 and BRCA2 (related to breast cancer). The chips are produced by using microlithography techniques traditionally used to fabricate integrated circuits (see below). | 1 | Applied and Interdisciplinary Chemistry |
* Fellow of the American Association for the Advancement of Science (1934)
* Fellow of the Indiana Academy of Science (1935)
* American Chemical Society
* Phi Beta Kappa
* Sigma Xi
* Tau Kappa Alpha
* Phi Lambda Upsilon
* Alpha Chi Sigma
* Lambda Chi Alpha | 0 | Theoretical and Fundamental Chemistry |
Alfred G. Gilman and Martin Rodbell received the 1994 Nobel Prize in Medicine and Physiology for the discovery of the G Protein System. | 1 | Applied and Interdisciplinary Chemistry |
Meyers early work featured explored the coordination chemistry of uranium with small molecules such as carbon dioxide and light alkanes. Additionally, Meyers group synthesized novel tripodal N-heterocyclic carbene ligands to stabilize reactive intermediates such as an iron(IV) nitride. In 2011, in collaboration with Prof. Jeremy M. Smith's group, Meyer achieved the first synthesis and characterization of a stable iron(V) nitride complex.
Other research highlights include:
* 2013: In collaboration with Prof. Ingo Krossing's group, the first crystallographic characterization of the 2-norbornyl cation, a prototypical non-classical carbocation whose exact structure has been debated for decades
* 2014: The synthesis of a novel tripodal redox-active ligand class, which was then used to stabilize a low-valent U(II) oxidation state complex
*2016: The first example of a uranium-based electrocatalyst for the reduction of water to dihydrogen, and the investigation of its reaction mechanism | 0 | Theoretical and Fundamental Chemistry |
Relatively few in-situ reactions have been reported involving gray arsenic due to its low solubility, although it reacts in air to form gaseous AsO . Two examples of the reactivity of gray arsenic towards transition metals are known. In these reactions, cyclopentadienyl complexes of molybdenum, tungsten and chromium proceed via loss of carbon monoxide to react with gray arsenic and form mono-, di-, and triarsenic compounds. | 0 | Theoretical and Fundamental Chemistry |
Spatiotemporal gene expression is the activation of genes within specific tissues of an organism at specific times during development. Gene activation patterns vary widely in complexity. Some are straightforward and static, such as the pattern of tubulin, which is expressed in all cells at all times in life. Some, on the other hand, are extraordinarily intricate and difficult to predict and model, with expression fluctuating wildly from minute to minute or from cell to cell. Spatiotemporal variation plays a key role in generating the diversity of cell types found in developed organisms; since the identity of a cell is specified by the collection of genes actively expressed within that cell, if gene expression was uniform spatially and temporally, there could be at most one kind of cell.
Consider the gene wingless, a member of the wnt family of genes. In the early embryonic development of the model organism Drosophila melanogaster, or fruit fly, wingless is expressed across almost the entire embryo in alternating stripes three cells separated. This pattern is lost by the time the organism develops into a larva, but wingless is still expressed in a variety of tissues such as the wing imaginal discs, patches of tissue that will develop into the adult wings. The spatiotemporal pattern of wingless gene expression is determined by a network of regulatory interactions consisting of the effects of many different genes such as even-skipped and Krüppel.
What causes spatial and temporal differences in the expression of a single gene? Because current expression patterns depend strictly on previous expression patterns, there is a regressive problem of explaining what caused the first differences in gene expression. The process by which uniform gene expression becomes spatially and temporally differential is known as symmetry breaking. For example, in the case of embryonic Drosophila development, the genes nanos and bicoid are asymmetrically expressed in the oocyte because maternal cells deposit messenger RNA (mRNA) for these genes in the poles of the egg before it is laid. | 1 | Applied and Interdisciplinary Chemistry |
Macrocycles can access a number of stable conformations, with preferences to reside in those that minimize the number of transannular nonbonded interactions within the ring. Medium rings (8-11 atoms) are the most strained with between 9-13 (kcal/mol) strain energy; analysis of the factors important in considering larger macrocyclic conformations can thus be modeled by looking at medium ring conformations. Conformational analysis of odd-membered rings suggests they tend to reside in less symmetrical forms with smaller energy differences between stable conformations. | 0 | Theoretical and Fundamental Chemistry |
Research chemicals are chemical substances scientists use for medical and scientific research purposes. One characteristic of a research chemical is that it is for laboratory research use only; a research chemical is not intended for human or veterinary use. This distinction is required on the labels of research chemicals and exempts them from regulation under parts 100-740 in Title 21 of the Code of Federal Regulations (21CFR). | 1 | Applied and Interdisciplinary Chemistry |
Anders Gustaf Ekeberg (16 January 1767 in Stockholm, Sweden – 11 February 1813 in Uppsala, Sweden) was a Swedish analytical chemist who discovered tantalum in 1802.
He was notably deaf. | 1 | Applied and Interdisciplinary Chemistry |
The town of Hinkley, California, located in the Mojave Desert, had its groundwater contaminated with hexavalent chromium starting in 1952, resulting in a legal case against Pacific Gas & Electric (PG&E) and a multimillion-dollar settlement in 1996. The legal case was dramatized in the film Erin Brockovich, released in 2000.
PG&E operates a compressor station in Hinkley for natural gas transmission pipelines. The natural gas has to be re-compressed approximately every , and the station uses large cooling towers to cool the gas after it has been compressed.
[http://www.swrcb.ca.gov/rwqcb6/water_issues/projects/pge/index.shtml Between 1952 and 1966], the water used in these cooling towers contained hexavalent chromium – now recognized as a carcinogen – to prevent rust in the machinery. The water was stored between uses in unlined ponds, which allowed it to percolate into the groundwater. This severely contaminated the groundwater, affecting soil and contaminating water wells near the compressor station, with a plume approximately long and nearly wide. | 1 | Applied and Interdisciplinary Chemistry |
Liquid is forced through a tube of constant cross-section and precisely known dimensions under conditions of laminar flow. Either the flow-rate or the pressure drop are fixed and the other measured. Knowing the dimensions, the flow-rate can be converted into a value for the shear rate and the pressure drop into a value for the shear stress. Varying the pressure or flow allows a flow curve to be determined. When a relatively small amount of fluid is available for rheometric characterization, a microfluidic rheometer with embedded pressure sensors can be used to measure pressure drop for a controlled flow rate.
Capillary rheometers are especially advantageous for characterization of therapeutic protein solutions since it determines the ability to be syringed. Additionally, there is an inverse relationship between the rheometry and solution stability, as well as thermodynamic interactions. | 1 | Applied and Interdisciplinary Chemistry |
Metal smiths demonstrated increasing technical sophistication, producing both utilitarian and status-linked items. During the latter phase, Michoacán emerged as a technological hub, with metal artifacts also appearing at the adjacent zones of Guerrero and Jalisco.
Alloys became more prevalent during the second phase, as metal workers experimented with color, strength and fluidity. Formerly utilitarian assemblages transformed, with new focus placed upon metallic status objects. Further, the appearance of a copper-tin bronze alloy suggests contact between West Mexico and Peru during this period. However, many of the alloys/alloy concentrations used in West Mexico appear to reflect local innovation.
Scholars such as Dorothy Hosler suggest that ancient Mesoamericans were unique in their attention to the peculiar aesthetic properties of metals, such as the brilliant sounds and colors evoked through the movement of metallic objects. The rather late emergence of metallurgy in ancient Mesoamerica likely contributed to its novelty and subsequent role as a marker of elite status.
It has been suggested that Mesoamerican metal smiths produced particular alloys with the chief aim of exploiting the alloys’ emergent color properties, particularly the vivid gold tones produced through infusion of tin, and the silver shades that develop at high arsenic concentrations. Notably, certain artifacts from West Mexico contain tin or arsenic at concentrations as high as 23 weight percent, while concentrations of alloying elements at roughly 2 to 5 weight percent are typically adequate for augmented strength and mechanical utility.
Metal smiths in pre-Columbian West Mexico particularly exploited the brilliance inherent in metallic sound and sheen, suggesting that their creations tended to occupy a sacred and symbolic space. Metallic colors, gold and silver, might have been connected with solar and lunar deities while bell sounds have been associated with fertility rituals and protection in warfare. | 1 | Applied and Interdisciplinary Chemistry |
A variety of minimally bioreactive metals are routinely implanted. The most commonly implanted form of stainless steel is 316L. Cobalt-chromium and titanium-based implant alloys are also permanently implanted. All of these are made passive by a thin layer of oxide on their surface. A consideration, however, is that metal ions diffuse outward through the oxide and end up in the surrounding tissue. Bioreaction to metal implants includes the formation of a small envelope of fibrous tissue. The thickness of this layer is determined by the products being dissolved, and the extent to which the implant moves around within the enclosing tissue. Pure titanium may have only a minimal fibrous encapsulation. Stainless steel, on the other hand, may elicit encapsulation of as much as 2 mm. | 1 | Applied and Interdisciplinary Chemistry |
Certain types of venom, such as those produced by venomous snakes, can also cause proteolysis. These venoms are, in fact, complex digestive fluids that begin their work outside of the body. Proteolytic venoms cause a wide range of toxic effects, including effects that are:
* cytotoxic (cell-destroying)
* hemotoxic (blood-destroying)
* myotoxic (muscle-destroying)
* hemorrhagic (bleeding) | 1 | Applied and Interdisciplinary Chemistry |
N-linked glycans have intrinsic and extrinsic functions.
Within the immune system, the N-linked glycans on an immune cell's surface will help dictate that migration pattern of the cell, e.g. immune cells that migrate to the skin have specific glycosylations that favor homing to that site. The glycosylation patterns on the various immunoglobulins including IgE, IgM, IgD, IgA, and IgG bestow them with unique effector functions by altering their affinities for Fc and other immune receptors. Glycans may also be involved in "self" and "non self" discrimination, which may be relevant to the pathophysiology of various autoimmune diseases.
In some cases, interaction between the N-glycan and the protein stabilizes the protein through complex electronic effects. | 0 | Theoretical and Fundamental Chemistry |
Ostrowska-Czubenko attended the Nicolaus Copernicus University in Toruń, majoring in chemistry. She graduated in 1972, defended her doctoral thesis eight years later, and completed her habilitation in 2002. She is associate professor in the Department of Chemistry at the Nicolaus Copernicus University, where she specializes in physical Chemistry and physicochemistry of polymers. | 0 | Theoretical and Fundamental Chemistry |
Carpanone is a naturally occurring lignan-type natural product most widely known for the remarkably complex way nature prepares it, and the similarly remarkable success that an early chemistry group, that of Orville L. Chapman, had at mimicking natures pathway. Carpanone is an organic compound first isolated from the carpano trees (Cinnamomum sp.') of Bougainville Island by Brophy and coworkers, trees from which the natural product derives its name. The hexacyclic lignan is one of a class of related diastereomers isolated from carpano bark as mixtures of equal proportion of the "handedness" of its components (i.e., racemic mixtures), and is notable in its stereochemical complexity, because it contains five contiguous stereogenic centers. The route by which this complex structure is achieved through biosynthesis involves a series of reactions that, almost instantly, take a molecule with little three-dimensionality to the complex final structure. Notably, Brophy and coworkers isolated the simpler carpacin, a phenylpropanoid with a 9-carbon framework, recognized its substructure as being dimerized within the complex carpanone structure, and proposed a hypothesis of how carpacin was converted to carpanone in plant cells:
* carpacin underwent loss of a methyl (-CH) group from the ring methoxy (-OCH) group to provide the phenol, desmethylcarpacin,
* this phenol intermediate then underwent a phenolic coupling to generate a dimeric intermediate, which was
* followed immediately by a Diels-Alder (4+2) cycloaddition reaction to create 2 new rings, to give the final carpanone product.
Remarkably, within two years, Chapman and coworkers were able to chemically design a route to mimic this proposed biosynthetic route, and achieved the synthesis of carpanone from carpacin in a single "pot", in about 50% yield.
Carpanone itself is limited in its pharmacologic and biologic activities, but related analogs arrived at by variations of the Brophy-Chapman approach have shown activities as tool compounds relevant to mammalian exocytosis and vesicular traffic, and provided therapeutic "hits" in antiinfective, antihypertensive, and hepatoprotective areas.
The original Chapman design and synthesis is considered a classic in total synthesis, and one that highlights the power of biomimetic synthesis. | 0 | Theoretical and Fundamental Chemistry |
Osteryoung was appointed to the faculty at Montana State University in 1967. She moved to Colorado State University a year later, where she worked in the Departments of Civil Engineering and Microbiology. In 1977, Osteryoung moved to the National Science Foundation, where she was the program director for chemical analysis.
Osteryoung was made associate professor at the State University of New York at Buffalo in 1979 and professor in 1982. In 1985 Osteryoung was awarded a Guggenheim Fellowship and spent a year at the University of Southampton, where she investigated the fundamentals of solid electrodes.
Osteryoung moved to North Carolina State University in 1992, where she served as head of department for two years. In 1994, she returned to the National Science Foundation, where she was made director of the division of chemistry. She was the first woman to win the Jacob F. Schoellkopf medal in 1992. | 0 | Theoretical and Fundamental Chemistry |
Jacques-Louis Soret died in Geneva on 13 May 1890.
His son was Charles Soret, a recognized physicist and chemist in his own right. | 1 | Applied and Interdisciplinary Chemistry |
Indene is deprotonated by butyl lithium and related reagents to give the equivalent of the indenyl anion:
:CH + BuLi → LiCH + BuH
The resulting lithium indenide can be used to prepare indenyl complexes by salt metathesis reactions of metal halides. When the metal halide is easily reduced, the trimethylstannylindenyl can be used as a source of indenyl anion:
:MeSnCH + TiCl → MeSnCl + CHTiCl
The M-C distances in indenyl complexes are comparable to those in cyclopentadienyl complexes. For the metallocenes M(Ind), ring slipping is evident for the case of M = Co and especially Ni, but not for M = Fe. A number of chelating or ansa-bis(indenyl complexes are known, such as those derived from 2,2'-bis(2-indenyl) biphenyl | 0 | Theoretical and Fundamental Chemistry |
The peptization of a liquid mixture is the process of converting the mixture into a colloid by shaking it with a suitable electrolyte called a peptizing agent. That is, the insoluble solid particles which have settled out of the mixture (i.e. the precipitate) are reformed into microscopic particles suspended in the mixture. Peptization is the reverse of flocculation, the aggregation of colloidal particles into precipitate; as such, it is also known as deflocculation.
This is particularly important in colloid chemistry or for precipitation reactions in an aqueous solution. When colloidal particles bear a same sign electric charge, they mutually repel each other and cannot aggregate together. Freshly precipitated aluminium or iron hydroxide is extremely difficult to filter because the very fine colloidal particles directly pass through a paper filter. To facilitate the filtration, the colloidal suspension must be first flocculated by adding a concentrated solution of salt to the system. Multivalent cations are more efficient flocculants than monovalent cations: . The electrical charges present at the surface of the particles are so "neutralised" and disappear. More correctly speaking, the electrical double layer existing at the surface of the particles is compressed by the added electrolyte and collapses at high ionic strength. The electrical repulsion no longer hinders the aggregation of particles and they can then coalesce to form a flocculent precipitate that is easy to filter. If the precipitate is washed with an excessive volume of deionised water, the electrical double layer present at the surface of the particles expands again and the electrical repulsion reappears: the precipitate peptizes and the particles pass again through the filter.
Peptization is also used in nanoparticle synthesis to make a large grouping of particles split into many primary particles. This is done by changing the surface properties, applying a charge, or by adding a surfactant.
In the synthesis of titania (titanium dioxide) nanoparticles, peptization involves adsorption of quaternary ammonium cation on the titania surface. This causes the surface to become positively charged. Electrostatic repulsion of the primary particles in the agglomerated titania breaks up the agglomerate into primary particles. The efficacy of adsorbates or suspension modification in imparting interparticle electrostatic repulsion is most commonly studied in terms of zeta potential. | 0 | Theoretical and Fundamental Chemistry |
A prominent early synthetic application of organoniobium chemistry was the use of dimethoxyethane niobium trichloride, NbCl(DME), as a reagent for the reductive coupling of imines with carbonyl compounds to form amino alcohols. This reagent has found further use in other pinacol-type reductive couplings. | 0 | Theoretical and Fundamental Chemistry |
Anomerization is the process of conversion of one anomer to the other. For reducing sugars, anomerization is referred to as mutarotation and occurs readily in solution and is catalyzed by acid and base. This reversible process typically leads to an anomeric mixture in which eventually an equilibrium is reached between the two single anomers.
The ratio of the two anomers is specific for the regarding sugar. For example, regardless of the configuration of the starting -glucose, a solution will gradually move towards being a mixture of approximately 64% β--glucopyranoside and 36% of α--glucopyranose. As the ratio changes, the optical rotation of the mixture changes; this phenomenon is called mutarotation. | 0 | Theoretical and Fundamental Chemistry |
The classic method for obtaining bismuthyl salts was the treatment of bismuth oxide () with nitric acid. This reaction produces bismuthyl salts such as BiO(NO and BiO(OH)(NO) as end products. The same bismuthyl salts precipitate when strongly acidic solutions of various bismuth compounds are diluted.
The formation of bismuthyl was also considered to be a process that constantly occurs as a result of hydrolysis. Thus, bismuth nitrate, Bi(NO</small> is often formed.
Bismuthyl chloride (BiOCl) is readily soluble in hydrochloric acid. Moreover, this process, like nitrate, proceeds through a reversible reaction; a shift of the reaction to the left or right also occurs along the line of hydrolysis, depending on the relative amount of water and the (residual) hydrochloric acid present. Adding water to a slightly acidic solution of ВіСl immediately causes the appearance of a white precipitate of basic bismuth chloride, BiOCl. When hydrochloric acid is added, the precipitate dissolves again, but it immediately falls out when more water is added. All other bismuth compounds behave in aqueous solutions similarly to chloride.
At elevated temperatures, the vapors of the metal combine rapidly with oxygen, forming the yellow trioxide, Bismuth(III) oxide|. When molten, at temperatures above 710 °C, this oxide corrodes any metal oxide and even platinum. On reaction with a base, it forms two series of oxyanions: , which is polymeric and forms linear chains, and . The anion in is a cubic octameric anion, , whereas the anion in is tetrameric.
In addition to bismuthyl itself, thiocompounds corresponding to bismuthyl salts are also considered indicative for the chemistry of bismuth, for example, gray thiobismuthyl chloride with the formula BiSCl and others similar to it. These substances, unlike bismuthyl salts, are very stable with respect to water, and can be easily prepared by the action of hydrogen sulfide gas on the corresponding bismuth trihalide. | 1 | Applied and Interdisciplinary Chemistry |
Pharmaceutical fraud involves deceptions which bring financial gain to a pharmaceutical company. It affects individuals and public and private insurers. There are several different schemes used to defraud the health care system which are particular to the pharmaceutical industry. These include: Good Manufacturing Practice (GMP) Violations, Off Label Marketing, Best Price Fraud, CME Fraud, Medicaid Price Reporting, and Manufactured Compound Drugs. Of this amount $2.5 billion was recovered through False Claims Act cases in FY 2010. Examples of fraud cases include the GlaxoSmithKline $3 billion settlement, Pfizer $2.3 billion settlement and Merck & Co. $650 million settlement. Damages from fraud can be recovered by use of the False Claims Act, most commonly under the qui tam provisions which rewards an individual for being a "whistleblower", or relator (law).
Every major company selling atypical antipsychotics—Bristol-Myers Squibb, Eli Lilly and Company, Pfizer, AstraZeneca and Johnson & Johnson—has either settled recent government cases, under the False Claims Act, for hundreds of millions of dollars or is currently under investigation for possible health care fraud. Following charges of illegal marketing, two of the settlements set records in 2009 for the largest criminal fines ever imposed on corporations. One involved Eli Lilly's antipsychotic Zyprexa, and the other involved Bextra, an anti-inflammatory medication used for arthritis. In the Bextra case, the government also charged Pfizer with illegally marketing another antipsychotic, Geodon; Pfizer settled that part of the claim for $301 million, without admitting any wrongdoing.
On 2 July 2012, GlaxoSmithKline pleaded guilty to criminal charges and agreed to a $3 billion settlement of the largest health-care fraud case in the U.S. and the largest payment by a drug company. The settlement is related to the company's illegal promotion of prescription drugs, its failure to report safety data, bribing doctors, and promoting medicines for uses for which they were not licensed. The drugs involved were Paxil, Wellbutrin, Advair, Lamictal, and Zofran for off-label, non-covered uses. Those and the drugs Imitrex, Lotronex, Flovent, and Valtrex were involved in the kickback scheme.
The following is a list of the four largest settlements reached with pharmaceutical companies from 1991 to 2012, rank ordered by the size of the total settlement. Legal claims against the pharmaceutical industry have varied widely over the past two decades, including Medicare and Medicaid fraud, off-label promotion, and inadequate manufacturing practices. | 1 | Applied and Interdisciplinary Chemistry |
The following were named after V. G. Khlopin:
*By resolution of the Presidium of the USSR Academy of Sciences, the Radium Institute was named after V. G. Khlopin (1950).
*The V. G. Khlopin Prize was established for the best work in the field of radiochemistry (1950).
*Since 1970, the Radium Institute has held Khlopin readings on radiochemistry and the chemistry of rare elements.
*Khlopin Street - in the Kalininsky district since 1972, from Polytechnicheskaya to Gzhatskaya streets.
*Radium Institute named after. V. G. Khlopin - 2nd Murinsky Avenue, building 28;
*Radium Institute named after. V. G. Khlopin (historical building) - Roentgen Street, building 1 (for more information about this building, see the article Roentgen Street). | 0 | Theoretical and Fundamental Chemistry |
The plate height given as:
with the column length and the number of theoretical plates can be estimated from a chromatogram by analysis of the retention time for each component and its standard deviation as a measure for peak width, provided that the elution curve represents a Gaussian curve.
In this case the plate count is given by:
By using the more practical peak width at half height the equation is:
or with the width at the base of the peak: | 0 | Theoretical and Fundamental Chemistry |
In biology, glycosylation is the process by which a carbohydrate is covalently attached to an organic molecule, creating structures such as glycoproteins and glycolipids. | 0 | Theoretical and Fundamental Chemistry |
In physical chemistry, when referring to surface processes, saturation denotes the degree at which a binding site is fully occupied. For example, base saturation refers to the fraction of exchangeable cations that are base cations. | 0 | Theoretical and Fundamental Chemistry |
In metazoans, in order to respond to environmental stress, differentiate properly, and progress normally through the cell cycle, a eukaryotic cell needs a specific and coordinated gene expression program, which involves the highly regulated transcription of thousands of genes. This gene regulation is in large part controlled, in a tissue-specific manner, by the binding of transcription factors to noncoding genomic regions referred to as cis-regulatory modules (CRMs), activating or repressing gene expression by modulating the structure of the chromatin and therefore having a positive or negative effect on transcription regulation. CRMs activating gene expression are often referred to as transcriptional enhancers, whereas those repressing gene expression are referred to as transcriptional silencers. | 1 | Applied and Interdisciplinary Chemistry |
For all human uses and all forms, selegiline is pregnancy category C: studies in pregnant lab animals have shown adverse effects on the fetus but there are no adequate studies in humans. | 0 | Theoretical and Fundamental Chemistry |
Experiments performed in microgravity on the Space Shuttle Columbia suggest that the typical face-centered cubic structure may be induced by gravitational stresses. Crystals tend to exhibit the hcp structure alone (random stacking of hexagonally close-packed crystal planes), in contrast with a mixture of (rhcp) and face-centred cubic packing when allowed sufficient time to reach mechanical equilibrium under gravitational forces on Earth. Glassy (disordered or amorphous) colloidal samples have become fully crystallized in microgravity in less than two weeks. | 0 | Theoretical and Fundamental Chemistry |
The Hammett substituent constant, , is composed of two independent terms: an inductive effect and a resonance polar effect . These components represent the consequences of the presence of a particular substituent on reactivity through sigma and pi bonds, respectively. For a particular substituent, the value of is generally assumed to be a constant, irrespective of the nature of the reaction; however, it has been shown that for reactions of para-substituted compounds in which the transition state bears a nearly full charge, does not remain constant, and thus, the sum is also variable. In other words, for such reactions, application of the standard Hammett Equation does not produce a linear plot. To correlate these deviations from linearity, Yasuhide Yukawa and Yuho Tsuno proposed a modification to the original Hammett equation which accounts exclusively for enhanced resonance effects due to the high electron demand during such reactions. | 0 | Theoretical and Fundamental Chemistry |
Cementite changes from ferromagnetic to paramagnetic upon heating to its Curie temperature of approximately .
A natural iron carbide (containing minor amounts of nickel and cobalt) occurs in iron meteorites and is called cohenite after the German mineralogist Emil Cohen, who first described it. | 1 | Applied and Interdisciplinary Chemistry |
Children and adolescents who use tanning beds are at greater risk because of biological vulnerability to UV radiation. Epidemiological studies have shown that exposure to artificial tanning increases the risk of malignant melanoma and that the longer the exposure, the greater the risk, particularly in individuals exposed before the age of 30 or who have been sunburned.
One study conducted among college students found that awareness of the risks of tanning beds did not deter the students from using them. Teenagers are frequent targets of tanning industry marketing, which includes offers of coupons and placing ads in high-school newspapers. Members of the United States House Committee on Energy and Commerce commissioned a "sting" operation in 2012, in which callers posing as a 16-year-old woman who wanted to tan for the first time called 300 tanning salons in the US. Staff reportedly failed to follow FDA recommendations, denied the risks of tanning, and offered misleading information about benefits. | 0 | Theoretical and Fundamental Chemistry |
A pneumatic gripper is a specific type of pneumatic actuator that typically involves either parallel or angular motion of surfaces, A.K.A. “tooling jaws or fingers” that will grip an object. The gripper makes use of compressed air which powers a piston rod inside the tool.Grippers exist both internal with and external bore grip with the same equipment because of an increased quantity of cross rollers in the parallel slide part. | 1 | Applied and Interdisciplinary Chemistry |
The NAPCO partnership was formed in 1877 by Queenslanders William Collins, William Forrest and Sir Thomas McIlwraith, with Englishmen John Warner and Sir William Ingram. The first station acquired was Alexandria Downs in the Northern Territory.
Francis Foster invested in NAPCO in 1937 taking an 18% interest which grew through his lifetime to 43%, bringing with it exceptional pastoral skills and a long-term vision.
Monkira and Coorabulka were acquired in 1939 as part of their plan to breed cattle at Alexandria and then fatten and sell from the Channel Country.
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In 1968 the company acquired Glenormiston along with the adjoining property, Marion Downs, at about the same time.
In May 2016, Queensland Investment Corporation acquired a 79% interest in NAPCO with the Foster family owning the remaining 21%.
In 2016 NAPCO was inducted into the Queensland Business Leaders Hall of Fame.
In January 2020 NAPCO announced it was purchasing Mantuan Downs, a large-scale cattle breeding and finishing property in Central Queensland. The property consists of two pastoral leases, known as Mantuan Downs and Castlevale as well as the freehold Semper Idem. | 1 | Applied and Interdisciplinary Chemistry |
The term clone is used in horticulture to refer to descendants of a single plant which were produced by vegetative reproduction or apomixis. Many horticultural plant cultivars are clones, having been derived from a single individual, multiplied by some process other than sexual reproduction. As an example, some European cultivars of grapes represent clones that have been propagated for over two millennia. Other examples are potato and banana.
Grafting can be regarded as cloning, since all the shoots and branches coming from the graft are genetically a clone of a single individual, but this particular kind of cloning has not come under ethical scrutiny and is generally treated as an entirely different kind of operation.
Many trees, shrubs, vines, ferns and other herbaceous perennials form clonal colonies naturally. Parts of an individual plant may become detached by fragmentation and grow on to become separate clonal individuals. A common example is in the vegetative reproduction of moss and liverwort gametophyte clones by means of gemmae. Some vascular plants e.g. dandelion and certain viviparous grasses also form seeds asexually, termed apomixis, resulting in clonal populations of genetically identical individuals. | 1 | Applied and Interdisciplinary Chemistry |
An easy way to produce fermented water is to obtain turbo yeast kits (contains Saccharomyces cerevisiae yeast strain, enzymes, vitamins, and minerals) that instructs on the package the quantity of white sugar, and tap water needed.
* Inverted sugar syrup
** Water
** Sugars in wine: White sugar (or crystallized sucrose) is cheap and common. Also, partial refined sugar like brown sugar should be avoided, for example molasses produces a distinct flavor in rum. Using plain sugar is beneficial over whole fruit; Methanol is a major occurrence in fruit spirits.
* Yeast in winemaking: The most common yeast associated with winemaking is Saccharomyces cerevisiae. Saccharomyces cerevisiae is excellent at producing ethanol. Yeast are dependent on a few nutrients (often included in yeast kit sanchets) to produce as much ethanol as possible, the most important ones are:
** Invertase is an enzyme that cleaves the glycosidic linkage between the glucose and fructose molecules in sucrose. This helps the yeast metabolize the sugars faster.
** Thiamine: Increases the resistance of the yeast Saccharomyces cerevisiae against oxidative, osmotic and thermal stress.
** Yeast assimilable nitrogen (YAN), is the combination of free amino nitrogen (FAN), ammonia (NH) and ammonium (NH) that is available for the wine yeast Saccharomyces cerevisiae to use during fermentation. Outside the sugars in wine, nitrogen is the most important nutrient needed to carry out a successful fermentation that doesn't end prior to the intended point of dryness or sees the development of off-odors and related wine faults. | 1 | Applied and Interdisciplinary Chemistry |
Silver overlay is an electroplated coating of silver on a non-conductive surface such as porcelain or glass. Most techniques used to create silver overlay involve the use of special flux which contains silver and turpentine oil. This is then painted on the glass ornament as a design. After the painting is complete, the entire ornament is fired under relatively low heat, it is then cleaned after being quenched and cooled, then it is placed in a solution of silver. A low voltage current is run through the solution and the silver binds in the design, creating a permanent fusion of the silver with the glass.
A much older technique of overlay, which was commonly used in the Indian subcontinent since ancient times, involves the use of a silver sheet wrapped around the ornament and then the design beaten onto the sheet or it may be burnished. This technique renders the design silhouetted against a dark backdrop and was commonly called the Aftabi design technique. This technique of overlay predates the technique that is common today, but without the use of electroplating, it was a time consuming and tedious process, which could only be accomplished by skilled artisans. | 1 | Applied and Interdisciplinary Chemistry |
The rotary kiln was invented in 1873 by Frederick Ransome. He filed several patents in 1885-1887, but his experiments with the idea were not a commercial success. Nevertheless, his designs provided the basis for successful kilns in the US from 1891, subsequently emulated worldwide. | 1 | Applied and Interdisciplinary Chemistry |
Oxaloacetate forms in several ways in nature. A principal route is upon oxidation of -malate, catalyzed by malate dehydrogenase, in the citric acid cycle. Malate is also oxidized by succinate dehydrogenase in a slow reaction with the initial product being enol-oxaloacetate. <br>
It also arises from the condensation of pyruvate with carbonic acid, driven by the hydrolysis of ATP:
:CHC(O)CO + HCO + ATP → OCCHC(O)CO + ADP + Pi
Occurring in the mesophyll of plants, this process proceeds via phosphoenolpyruvate, catalysed by phosphoenolpyruvate carboxylase. <br>Oxaloacetate can also arise from trans- or de- amination of aspartic acid. | 1 | Applied and Interdisciplinary Chemistry |
The Pasteur point is a level of oxygen (about 0.3% by volume which is less than 1% of Present Atmospheric Level or PAL) above which facultative aerobic microorganisms and facultative anaerobes adapt from fermentation to aerobic respiration. It is also used to mark the level of oxygen in the early atmosphere of the Earth that is believed to have led to major evolutionary changes. It is named after Louis Pasteur, the French microbiologist who studied anaerobic microbial fermentation, and is related to the Pasteur effect.
It was once supposed that about 400 million years ago, in the Cambrian period, the level of oxygen in the atmosphere rose from 0.1 to 1 percent of present atmospheric level. Supposedly, this led to many organisms adapting from fermentation to respiration, leading to organisms evolving photosynthesis and what is termed the Cambrian explosion of species. It has also been suggested that this increased oxygen level reduced the influence of ultraviolet radiation.
It is now well documented that oxygen level reached at least 10% of the present value 2.4 billion years ago (for details see Great Oxygenation Event). | 1 | Applied and Interdisciplinary Chemistry |
Subsets and Splits