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Arner et al. identified 65,423 transcribed enhancers (producing eRNA) among 33 different cell types under different conditions and different timings of stimulation. The transcription of enhancers generally preceded transcription of transcription factors which, in turn, generally preceded messenger RNA(mRNA) transcription of genes.
Carullo et al. examined one particular cell type, neurons (from primary neuron cultures). They exhibited 28,492 putative enhancers generating eRNAs. These eRNAs were often transcribed from both strands of the enhancer DNA in opposite directions. Carullo et al. used these cultured neurons to examine the timing of specific enhancer eRNAs compared to the mRNAs of their target genes. The cultured neurons were activated and RNA was isolated from those neurons at 0, 3.75, 5, 7.5, 15, 30, and 60 minutes after activation. In these experimental conditions, they found that 2 of the 5 enhancers of the immediate early gene (IEG) FOS, that is FOS enhancer 1 and FOS enhancer 3, became activated and initiated transcription of their eRNAs (eRNA1 and eRNA3). FOS eRNA1 and eRNA3 were significantly up-regulated within 7.5 minutes, whereas FOS mRNA was only upregulated 15 minutes after stimulation. Similar patterns occurred at IEGs FOSb and NR4A1, indicating that for many IEGs, eRNA induction precedes mRNA induction in response to neuronal activation.
While some enhancers can activate their target promoters at their target genes without transcribing eRNA, most active enhancers do transcribe eRNA during activation of their target promoters. | 1 | Applied and Interdisciplinary Chemistry |
Ring-shaped phosphorus was theoretically predicted in 2007. The ring-shaped phosphorus was self-assembled inside evacuated multi-walled carbon nanotubes with inner diameters of 5–8 nm using a vapor encapsulation method. A ring with a diameter of 5.30 nm, consisting of 23 and 23 units with a total of 230 P atoms, was observed inside a multi-walled carbon nanotube with an inner diameter of 5.90 nm in atomic scale. The distance between neighboring rings is 6.4 Å.
The Hexaphosphabenzene| ring shaped molecule is not stable in isolation. | 0 | Theoretical and Fundamental Chemistry |
There is no limit to the number of possible organic reactions and mechanisms. However, certain general patterns are observed that can be used to describe many common or useful reactions. Each reaction has a stepwise reaction mechanism that explains how it happens, although this detailed description of steps is not always clear from a list of reactants alone. Organic reactions can be organized into several basic types. Some reactions fit into more than one category. For example, some substitution reactions follow an addition-elimination pathway. This overview isn't intended to include every single organic reaction. Rather, it is intended to cover the basic reactions.
In condensation reactions a small molecule, usually water, is split off when two reactants combine in a chemical reaction. The opposite reaction, when water is consumed in a reaction, is called hydrolysis. Many polymerization reactions are derived from organic reactions. They are divided into addition polymerizations and step-growth polymerizations.
In general the stepwise progression of reaction mechanisms can be represented using arrow pushing techniques in which curved arrows are used to track the movement of electrons as starting materials transition to intermediates and products. | 0 | Theoretical and Fundamental Chemistry |
Evolution of microbial resistance to vancomycin is a growing problem, in particular, within healthcare facilities such as hospitals. While newer alternatives to vancomycin exist, such as linezolid (2000) and daptomycin (2003), the widespread use of vancomycin makes resistance to the drug a significant worry, especially for individual patients if resistant infections are not quickly identified and the patient continues the ineffective treatment. Vancomycin-resistant Enterococcus emerged in 1986. Vancomycin resistance evolved in more common pathogenic organisms during the 1990s and 2000s, including vancomycin-intermediate S. aureus (VISA) and vancomycin-resistant S. aureus (VRSA). Agricultural use of avoparcin, another similar glycopeptide antibiotic, may have contributed to the evolution of vancomycin-resistant organisms.
One mechanism of resistance to vancomycin involves the alteration to the terminal amino acid residues of the NAM/NAG-peptide subunits, under normal conditions, -alanyl--alanine, to which vancomycin binds. The -alanyl--lactate variation results in the loss of one hydrogen-bonding interaction (4, as opposed to 5 for -alanyl--alanine) possible between vancomycin and the peptide. This loss of just one point of interaction results in a 1000-fold decrease in affinity. The -alanyl--serine variation causes a six-fold loss of affinity between vancomycin and the peptide, likely due to steric hindrance.
In enterococci, this modification appears to be due to the expression of an enzyme that alters the terminal residue. Three main resistance variants have been characterised to date among resistant Enterococcus faecium and E. faecalis populations:
* VanA - enterococcal resistance to vancomycin and teicoplanin; inducible on exposure to these agents
* VanB - lower-level enterococcal resistance; inducible by vancomycin, but strains may remain susceptible to teicoplanin
* VanC - least clinically important; enterococci resistant only to vancomycin; constitutive resistance
Variant of vancomycin has been tested that binds to the resistant D-lactic acid variation in vancomycin-resistant bacterial cell walls, and also binds well to the original target (vancomycin-susceptible bacteria). | 0 | Theoretical and Fundamental Chemistry |
Once correctly positioned in the membrane via binding of PIP3, Akt can then be phosphorylated by its activating kinases, phosphoinositide-dependent kinase 1 (PDK1) and PDK2. Serine473, the hydrophobic motif, is phosphorylated in an mTORC2-dependent manner, leading some investigators to hypothesize that mTORC2 is the long-sought PDK2 molecule. Threonine308, the activation loop, is phosphorylated by PDK1, allowing full Akt activation. Activated Akt can then go on to activate or deactivate its myriad substrates via its kinase activity. The PHLPPs therefore antagonize PDK1 and PDK2, since they dephosphorylate the site that PDK2 phosphorylates. | 1 | Applied and Interdisciplinary Chemistry |
A growing number of scientists agree that there is an urgent need to protect the public by being able to forecast harmful algal blooms. One way they hope to do that is with sophisticated sensors which can help warn about potential blooms. The same types of sensors can also be used by water treatment facilities to help them prepare for higher toxic levels.
The only sensors now in use are located in the Gulf of Mexico. In 2008 similar sensors in the Gulf forewarned of an increased level of toxins that led to a shutdown of shellfish harvesting in Texas along with a recall of mussels, clams, and oysters, possibly saving many lives. With an increase in the size and frequency of HABs, experts state the need for significantly more sensors located around the country. The same kinds of sensors can also be used to detect threats to drinking water from intentional contamination.
Satellite and remote sensing technologies are growing in importance for monitoring, tracking, and detecting HABs. Four U.S. federal agencies—EPA, the National Aeronautics and Space Administration (NASA), NOAA, and the U.S. Geological Survey (USGS)—are working on ways to detect and measure cyanobacteria blooms using satellite data. The data may help develop early-warning indicators of cyanobacteria blooms by monitoring both local and national coverage. In 2016 automated early-warning monitoring systems were successfully tested, and for the first time proven to identify the rapid growth of algae and the subsequent depletion of oxygen in the water. | 0 | Theoretical and Fundamental Chemistry |
Innate immune system senses intact peptidoglycan and peptidoglycan fragments using numerous PRRs (pattern recognition receptors) that are secreted, expressed intracellularly or expressed on the cell surface. | 1 | Applied and Interdisciplinary Chemistry |
Many studies have proposed that induction of EMT is the primary mechanism by which epithelial cancer cells acquire malignant phenotypes that promote metastasis. Drug development targeting the activation of EMT in cancer cells has thus become an aim of pharmaceutical companies. | 1 | Applied and Interdisciplinary Chemistry |
Single-Entity Electrochemistry (SEE) refers to the electroanalysis of an individual unit of interest. A unique feature of SEE is that it unifies multiple different branches of electrochemistry. Single-Entity Electrochemistry pushes the bounds of the field as it can measure entities on a scale of 100 microns to angstroms. Single-Entity Electrochemistry is important because it gives the ability to view how a single molecule, or cell, or "thing" affects the bulk response, and thus the chemistry that might have gone unknown otherwise. The ability to monitor the movement of one electron or ion from one unit to another is valuable, as many vital reactions and mechanisms undergo this process. Electrochemistry is well suited for this measurement due to its incredible sensitivity. Single-Entity Electrochemistry can be used to investigate nanoparticles, wires, vesicles, nanobubbles, nanotubes, cells, and viruses, and other small molecules and ions. Single-entity electrochemistry has been successfully used to determine the size distribution of particles as well as the number of particles present inside a vesicle or other similar structures | 0 | Theoretical and Fundamental Chemistry |
Biosensors are attached to a substance of interest. Normally, this substance would not be able to absorb light, but with the attached biosensor, light can be absorbed and emitted on a spectrophotometer. Additionally, biosensors that are fluorescent can be viewed with the naked eye. Some fluorescent biosensors also have the ability to change color in changing environments (ex: from blue to red). A researcher would be able to inspect and get data about the surrounding environment based on what color he or she could see visibly from the biosensor-molecule hybrid species.
Colorimetric assays are normally used to determine how much concentration of one species there is relative to another. | 1 | Applied and Interdisciplinary Chemistry |
The dynemicins are a sub-family of enediynes whose members are organic compounds generated in Micromonospora chersina. Dynemicin A was the first member of this sub-family to be discovered. It was isolated from M. chersina in a soil sample taken from the state of Gujarat in India. Dynemicins are violet in color because they contain anthraquinone as a variable group attached to the enediyne core. Dynemycins have demonstrated strong antitumor activity against leukemia and melanoma cells. | 0 | Theoretical and Fundamental Chemistry |
The HTL process differs from pyrolysis as it can process wet biomass and produce a bio-oil that contains approximately twice the energy density of pyrolysis oil. Pyrolysis is a related process to HTL, but biomass must be processed and dried in order to increase the yield. The presence of water in pyrolysis drastically increases the heat of vaporization of the organic material, increasing the energy required to decompose the biomass. Typical pyrolysis processes require a water content of less than 40% to suitably convert the biomass to bio-oil. This requires considerable pretreatment of wet biomass such as tropical grasses, which contain a water content as high as 80-85%, and even further treatment for aquatic species, which can contain higher than 90% water content.
The HTL oil can contain up to 80% of the feedstock carbon content (single pass). HTL oil has good potential to yield bio-oil with "drop-in" properties that can be directly distributed in existing petroleum infrastructure.
The energy returned on energy invested (EROEI) of these processes is uncertain and/or has not been measured. Furthermore, products of hydrous pyrolysis might not meet current fuel standards. Further processing may be required to produce fuels. | 0 | Theoretical and Fundamental Chemistry |
Infrared photodissociation spectroscopy maintains a powerful capability to study bond energies of coordination complexes. IRPD can measure varying bond energies of compounds, including dative bonds and coordination energies of molecular clusters. Structural information about analytes can acquired by using mass selectivity and interpreting fragmentation. The spectroscopic information usually resembles that of linear infrared spectra and can be used to obtain detailed structural information of gas-phase species, in case of metal complexes, insights into ligand coordination, bond activations and successive reactions can be obtained. | 0 | Theoretical and Fundamental Chemistry |
A series of samples are prepared with all the same receptor (R) concentration but in which the ligand (L) concentration is titrated. After equilibrium is reached each sample is measured by flowing it through the column (Figure 2).
For 1:1 reversible binding Equilibrium Kd is defined as
(1) K≡k/k =R*L/RL
the binding is reversible so conservation of mass can be written as
(2) R = R+RL
(3) L = L +RL
Where:
K = equilibrium dissociation constant
k = forward rate constant
k = reverse rate constant
R = free receptor site concentration at equilibrium
L = free ligand site concentration at equilibrium
RL = concentration of complex at equilibrium
R= total concentration of receptors
L = total concentration of ligand
A simple equation relating the free fraction of R (=R/R) to the K and L is then fit to the measured data to find the K of the interaction. | 1 | Applied and Interdisciplinary Chemistry |
Isomers having distinct biological properties are common; for example, the placement of methyl groups. In substituted xanthines, theobromine, found in chocolate, is a vasodilator with some effects in common with caffeine; but, if one of the two methyl groups is moved to a different position on the two-ring core, the isomer is theophylline, which has a variety of effects, including bronchodilation and anti-inflammatory action. Another example of this occurs in the phenethylamine-based stimulant drugs. Phentermine is a non-chiral compound with a weaker effect than that of amphetamine. It is used as an appetite-reducing medication and has mild or no stimulant properties. However, an alternate atomic arrangement gives dextromethamphetamine, which is a stronger stimulant than amphetamine.
In medicinal chemistry and biochemistry, enantiomers are a special concern because they may possess distinct biological activity. Many preparative procedures afford a mixture of equal amounts of both enantiomeric forms. In some cases, the enantiomers are separated by chromatography using chiral stationary phases. They may also be separated through the formation of diastereomeric salts. In other cases, enantioselective synthesis have been developed.
As an inorganic example, cisplatin (see structure above) is an important drug used in cancer chemotherapy, whereas the trans isomer (transplatin) has no useful pharmacological activity. | 0 | Theoretical and Fundamental Chemistry |
mTOR inhibitors are a class of drugs used to treat several human diseases, including cancer, autoimmune diseases, and neurodegeneration. They function by inhibiting the mammalian target of rapamycin (mTOR) (also known as the mechanistic target of rapamycin), which is a serine/threonine-specific protein kinase that belongs to the family of phosphatidylinositol-3 kinase (PI3K) related kinases (PIKKs). mTOR regulates cellular metabolism, growth, and proliferation by forming and signaling through two protein complexes, mTORC1 and mTORC2. The most established mTOR inhibitors are so-called rapalogs (rapamycin and its analogs), which have shown tumor responses in clinical trials against various tumor types. | 1 | Applied and Interdisciplinary Chemistry |
The KhAB-250 is the provisional naming of an aerial bomb developed by the Soviet Air Force to deliver the chemical weapon sarin.
The KhAB-250 operational weight has been reported as and . 24 could be carried by the Tupolev Tu-22.
The bomb uses a burst charge to detonate on impact with the ground. It contains a payload of of sarin.
The KhAB-250 was displayed at Shikani Test and Proving Grounds in 1986 as a component of the then-current Soviet chemical arsenal. Contemporary analysts noted that it appeared relatively unsophisticated compared to Soviet conventional munitions of the same time frame.
The bomb was removed from service as a result of the Chemical Weapons Convention in the early 1990s. | 1 | Applied and Interdisciplinary Chemistry |
MTBE is used as a fuel component in fuel for gasoline engines. It is one of a group of chemicals commonly known as oxygenates because they raise the oxygen content of gasoline. | 1 | Applied and Interdisciplinary Chemistry |
In the presence of very reactive dienes (for example 1,3-diphenylisobenzofuran) butadienesulfone behaves as a dienophile and forms the corresponding Diels-Alder adduct.
As early as 1938, Kurt Alder and co-workers reported Diels-Alder adducts from the isomeric 2-sulfolene with 1,3-butadiene and 2-sulfolene with cyclopentadiene. | 0 | Theoretical and Fundamental Chemistry |
Another approach to prevent or reduce PD formation is by modifying the primers so that annealing with themselves or each other does not cause extension.
HANDS (Homo-Tag Assisted Non-Dimer System): a nucleotide tail, complementary to the 3 end of the primer is added to the 5 end of the primer. Because of the close proximity of the 5 tail it anneals to the 3 end of the primer. The result is a stem-loop primer that excludes annealing involving shorter overlaps, but permits annealing of the primer to its fully complementary sequence in the target.
Chimeric primers: some DNA bases in the primer are replaced with RNA bases, creating a chimeric sequence. The melting temperature of a chimeric sequence with another chimeric sequence is lower than that of chimeric sequence with DNA. This difference enables setting the annealing temperature such that the primer will anneal to its target sequence, but not to other chimeric primers.
Blocked-cleavable primers: a method known as RNase H-dependent PCR (rhPCR), utilizes a thermostable RNase HII to remove a blocking group from the PCR primers at high temperature. This RNase HII enzyme displays almost no activity at low temperature, making the removal of the block only occur at high temperature. The enzyme also possess inherent primer:template mismatch discrimination, resulting in additional selection against primer-dimers.
Self-Avoiding molecular recognition systems :also known as SAMRS, eliminating primer dimers by introducing nucleotide analogues T*, A*, G* and C* into the primer. The SAMRS DNA could bind to natural DNA, but not to other members of the same SAMRS species. For example, T* could bind to A but not A*, and A* could bind to T but not T*. Thus, through careful design, primers build from SAMRS could avoid primer-primer interactions and allowing sensitive SNP detection as well as multiplex PCR. | 1 | Applied and Interdisciplinary Chemistry |
A Ludwieg tube is a wind tunnel that produces supersonic flow for short periods of time. A large evacuated dump tank is separated from the downstream end of a convergent-divergent nozzle by a diaphragm or fast acting valve. The upstream end of the nozzle connects to a long cylindrical tube, whose cross-sectional area is significantly larger than the throat area of the nozzle. Initially, the pressure in the nozzle and tube is high. To start the tunnel, the diaphragm is ruptured, e.g., by piercing it with a suitable cutting device, or opening the valve respectively. As always when a diaphragm ruptures, a shock wave propagates into the low-pressure region (here the dump tank) and an expansion wave propagates into the high-pressure region (here the nozzle and the long tube). As this unsteady expansion propagates through the long tube, it sets up a steady subsonic flow toward the nozzle, which is accelerated by the convergent-divergent nozzle to a supersonic condition. The flow is steady until the expansion, having been reflected from the far end of the tube, arrives at the nozzle again. For practical reasons, flow times are about 100 milliseconds for most Ludwieg tubes. For many purposes, this flow duration is sufficient. However, by taking advantage of multiple quasi-static flows between expansion wave reflections, experimentation times of up to 6 seconds can be achieved. | 1 | Applied and Interdisciplinary Chemistry |
PSII, PSI, and cytochrome bf are found in chloroplasts. All plants and all photosynthetic algae contain chloroplasts, which produce NADPH and ATP by the mechanisms described above. In essence, the same transmembrane structures are also found in cyanobacteria.
Unlike plants and algae, cyanobacteria are prokaryotes. They do not contain chloroplasts; rather, they bear a striking resemblance to chloroplasts themselves. This suggests that organisms resembling cyanobacteria were the evolutionary precursors of chloroplasts. One imagines primitive eukaryotic cells taking up cyanobacteria as intracellular symbionts in a process known as endosymbiosis. | 0 | Theoretical and Fundamental Chemistry |
Flockhart had joined John Duncan (also from Kinrosshire, who was 28 years his senior), as a partner in 1833, having started as an apprentice surgeon-apothecary and qualifying as a licenciate of the Royal College of Surgeons Edinburgh in 1830, when he was 22 years old. He did not practise as a surgeon, but with Duncan, worked closely with other doctors in Edinburgh on experimental drugs, which they then refined to improve in purity, following the medical experiments results. They were both among the nine founder members of the Northern British Branch of the Pharmaceutical Society (in 1841) and joined the Edinburgh Merchant Company. The second annual dinner of the Pharmaceutical Society included a toast to strangers present by Flockhart, and three years later he was elected president. In his inaugural speech he highlighted the issues on unregulated production, of poisons for example, and the risks from a lack of quality controls, and thus he proposed a Universal Phamacopoeia for Great Britain'. In December 1861, Flockhart was also elected to the Edinburgh Chamber of Commerce.
Duncan and Flockhart had premises at 52 North Bridge, Edinburgh (now the Balmoral Hotel) which has a plaque to the pharmacists, dedicated 1981, by the International Association for the Study of Pain.
The retail pharmacy business under Flockhart's management flourished and another branch at 139 Princes Street, Edinburgh opened in 1846. From 1855 to 1865, Flockhart managed the business and it moved to 6 North Bridge. Duncan, Flockhart and Company manufacturing partnership later extended to a factory at 1 Constitution Street, Leith. When Duncan died, Flockhart continued to partner with his son Doctor James Duncan, and the firm extended rapidly and grew its business on the back of the growing demand for chloroform and other drugs or analgesics.
Flockhart died at Annacroich, after sudden onset of severe stomach pains, although medical colleagues came from Edinburgh to his aid, in August 1871, aged 62, and was buried at Warriston Cemetery, Edinburgh, near to where James Young Simpson is also buried. His death announcement appeared in the Stonehaven Journal.
His son (also) William Flockhart took over the business of Duncan, Flockhart and Company Limited with James Duncan and he lived at 4 Gayfield Square, Edinburgh. The chemist company that Duncan and Flockhart had begun continued to operate in various forms in North Bridge, Edinburgh up until 1976, and later merged into large international pharma companies. | 1 | Applied and Interdisciplinary Chemistry |
A stratified fluid may be defined as the fluid with density variations in the vertical direction. For example, air and water; both are fluids and if we consider them together then they can be seen as a stratified fluid system. Density variations in the atmosphere profoundly affect the motion of water and air. Wave phenomena in air flow over the mountains and occurrence of smog are the examples of stratification effect in the atmosphere.
When a fluid system having a condition in which fluid density decreases with height, is disturbed, then the gravity and friction restore the undisturbed conditions. If however the fluid tends to be stable if density decreases with height. | 1 | Applied and Interdisciplinary Chemistry |
For black body emitters where photon recirculation is achieved via filters, Planck's law states that a black body emits light with a spectrum given by:
where I′ is the light flux of a specific wavelength, λ, given in units of 1 m⋅s. h is the Planck constant, k is the Boltzmann constant, c is the speed of light, and T is the emitter temperature. Thus, the light flux with wavelengths in a specific range can be found by integrating over the range. The peak wavelength is determined by the temperature, T based on Wien's displacement law:
where b is Wien's displacement constant. For most materials, the maximum temperature an emitter can stably operate at is about 1800 °C. This corresponds to an intensity that peaks at or an energy of ~0.75 eV. For more reasonable operating temperatures of 1200 °C, this drops to ~0.5 eV. These energies dictate the range of bandgaps that are needed for practical TPV converters (though the peak spectral power is slightly higher). Traditional PV materials such as Si (1.1 eV) and GaAs (1.4 eV) are substantially less practical for TPV systems, as the intensity of the black body spectrum is low at these energies for emitters at realistic temperatures. | 0 | Theoretical and Fundamental Chemistry |
Conversion of vegetable oil to biodiesel is via a transesterification reaction, where a triglyceride is converted to the methyl esters (of the fatty acids) plus glycerol. This is usually done using methanol and caustic or acid catalysts, but can be achieved using supercritical methanol without a catalyst. The method of using supercritical methanol for biodiesel production was first studied by Saka and his coworkers. This has the advantage of allowing a greater range and water content of feedstocks (in particular, used cooking oil), the product does not need to be washed to remove catalyst, and is easier to design as a continuous process. | 0 | Theoretical and Fundamental Chemistry |
Electrical pulses are also used to intracellularly deliver siRNA into cells. The cell membrane is made of phospholipids which makes it susceptible to an electric field. When quick but powerful electrical pulses are initiated the lipid molecules reorient themselves, while undergoing thermal phase transitions because of heating. This results in the making of hydrophilic pores and localized perturbations in the lipid bilayer cell membrane also causing a temporary loss of semipermeability. This allows for the escape of many intracellular contents, such as ions and metabolites as well as the simultaneous uptake of drugs, molecular probes, and nucleic acids. For cells that are difficult to transfect electroporation is advantageous however cell death is more probable under this technique.
This method has been used to deliver siRNA targeting VEGF into the xenografted tumors in nude mice, which resulted in a significant suppression of tumor growth. | 1 | Applied and Interdisciplinary Chemistry |
MgCu is a binary intermetallic compound of magnesium (Mg) and copper (Cu) adopting cubic crystal structure, more specifically the C15 Laves phase. The space group of MgCu is Fdm with lattice parameter a = 7.04 Å. | 1 | Applied and Interdisciplinary Chemistry |
In the electronics industry, octafluoropropane is mixed with oxygen and used as a plasma etching material for SiO layers in semiconductor applications, as oxides are selectively etched versus their metal substrates.
In medicine, octafluoropropane may compose the gas cores of microbubble contrast agents used in contrast-enhanced ultrasound. Octafluoropropane microbubbles reflect sound waves well and are used to improve the ultrasound signal backscatter.
It is used in eye surgery, such as pars plana vitrectomy procedures where a retina hole or tear is repaired. The gas provides a long-term tamponade, or plug, of a retinal hole or tear and allows re-attachment of the retina to occur over the several days following the procedure.
Under the name R-218, octafluoropropane is used in other industries as a component of refrigeration mixtures.
It has been featured in some plans for terraforming Mars. With a greenhouse gas effect 24,000 times greater than carbon dioxide (CO), octafluoropropane could dramatically reduce the time and resources it takes to terraform Mars.
It is the active liquid in PICO-2L dark matter bubble detector (joined PICASSO and COUPP collaborations). | 1 | Applied and Interdisciplinary Chemistry |
LEAPER is analogous to CRISPR Cas-13 in that it targets RNA before proteins are synthesized. However, LEAPER is simpler and more efficient as it only requires , rather than Cas and a guide RNA. According to the developers of LEAPER, it has the potential to be easier and more precise than any CRISPR technique.
LEAPER also eliminates health concerns and technical barriers arising from the introduction of exogenous proteins.
It has also been called more ethical as it does not change DNA and thus does not result in heritable changes, unlike methods using CRISPR Cas-9. | 1 | Applied and Interdisciplinary Chemistry |
There are seemingly two independent formulations of the third law of thermodynamics both originally were stated by Walther Nernst. The first formulation is known as the Nernst heat theorem, and can be phrased as:
*The entropy of any pure substance in thermodynamic equilibrium approaches zero as the temperature approaches zero.
The second formulation is dynamical, known as the unattainability principle
*It is impossible by any procedure, no matter how idealized, to reduce any assembly to absolute zero temperature in a finite number of operations.
At steady state the second law of thermodynamics implies that the total entropy production is non-negative.
When the cold bath approaches the absolute zero temperature,
it is necessary to eliminate the entropy production divergence at the cold side
when , therefore
For the fulfillment of the second law depends on the entropy production of the other baths,
which should compensate for the negative entropy production of the cold bath.
The first formulation of the third law modifies this restriction.
Instead of the third law imposes ,
guaranteeing that at absolute zero the entropy production at the cold bath is zero: .
This requirement leads to the scaling condition of the heat current .
The second formulation, known as the unattainability principle can be rephrased as;
*No refrigerator can cool a system to absolute zero temperature at finite time.
The dynamics of the cooling process is governed by the equation:
where is the heat capacity of the bath. Taking and with , we can quantify this formulation by evaluating the characteristic exponent of the cooling process,
This equation introduces the relation between the characteristic exponents and . When then the bath is cooled to zero temperature in a finite time, which implies a violation of the third law. It is apparent from the last equation, that the unattainability principle is more restrictive than the Nernst heat theorem. | 0 | Theoretical and Fundamental Chemistry |
The pillar does not bear an inscription mentioning its erector, date or purpose. It is located at Dhar, which was the capital of the Paramara dynasty. According to the local tradition, the pillar commemorates a military victory of the 11th century Paramara king Bhoja, whose knowledge of iron metallurgy can be seen in his book Yuktikalpataru. Henry Cousens of Archaeological Survey of India (ASI) theorized that it was constructed by the later Paramara king Arjunavarman in 1210 CE, from the molten arms of an enemy force.
The Lat Masjid, in whose compound the pillar is located, was constructed with spolia from Hindu and Jain temples. R. Balasubramaniam theorizes that a Shiva temple previously occupied the site, and the pillar was originally located at the front of this temple, with a trishula (trident) at the top.
The two largest fragments have a number of holes at irregular intervals, on all sides. The depth of the holes ranges from , and their diameter ranges from . Because they are distributed unevenly, they do not appear to be slots for lamps (as in a deepa-stambha). Cousens speculated that these were used by the forgers and welders to handle the pillar with their instruments during the manufacturing process. Roessler agreed with this hypothesis, and proposed that these slots were also used to hold the pillar upright using iron anchors.
The pillar appears to have been built using horizontal forge welding technique. Brahm Prakash theorized that smaller sections, measuring to in length, were joined together to form the pillar. | 1 | Applied and Interdisciplinary Chemistry |
The Deacon process, invented by Henry Deacon, is a process used during the manufacture of alkalis (the initial end product was sodium carbonate) by the Leblanc process. Hydrogen chloride gas was converted to chlorine gas, which was then used to manufacture a commercially valuable bleaching powder, and at the same time the emission of waste hydrochloric acid was curtailed. To some extent this technically sophisticated process superseded the earlier manganese dioxide process. | 0 | Theoretical and Fundamental Chemistry |
CK is often determined routinely in a medical laboratory. It used to be determined specifically in patients with chest pain, but this test has been replaced by troponin. Normal values at rest are usually between 60 and 400 IU/L, where one unit is enzyme activity, more specifically the amount of enzyme that will catalyze 1 μmol of substrate per minute under specified conditions (temperature, pH, substrate concentrations and activators.) This test is not specific for the type of CK that is elevated.
Creatine kinase in the blood may be high in health and disease. Exercise increases the outflow of creatine kinase to the blood stream for up to a week, and this is the most common cause of high CK in blood. Furthermore, high CK in the blood may be related to high intracellular CK such as in persons of African descent.
Finally, high CK in the blood may be an indication of damage to CK-rich tissue, such as in rhabdomyolysis, myocardial infarction, myositis and myocarditis. This means creatine kinase in blood may be elevated in a wide range of clinical conditions including the use of medication such as statins; endocrine disorders such as hypothyroidism; and skeletal muscle diseases and disorders including malignant hyperthermia, and neuroleptic malignant syndrome.
Furthermore, the isoenzyme determination has in the past been used extensively as an indication for myocardial damage in heart attacks. Troponin measurement has largely replaced this in many hospitals, although some centers still rely on CK-MB. | 1 | Applied and Interdisciplinary Chemistry |
In coordination chemistry, a transition metal NHC complex is a metal complex containing one or more N-heterocyclic carbene ligands. Such compounds are the subject of much research, in part because of prospective applications in homogeneous catalysis. One such success is the second generation Grubbs catalyst.
Historically, N-heterocyclic carbenes were thought to mimic properties of tertiary phosphines. Many steric and electronic differences exist between the two ligands. Compared to phosphine ligands, NHC ligands' cone angle is more complex. The imidazole ring of the NHC ligand is angled away from the metal center, yet the substituents at the 1,3 positions of the imidazole ring are angled towards it. The presence of the ligand inside of the metal coordination sphere affects the metal reactivity. In terms of electronic effects, NHC are often stronger sigma donation. | 0 | Theoretical and Fundamental Chemistry |
Laser light is sent to the sample and the outcoming transmitted or backscattered light is detected by an optoelectric sensor. The light intensity detected is the result of the interference of all the optical waves coming from the different light paths.
The signal is analysed by calculating the intensity autocorrelation function called g.
For the case of non-interacting particles suspended in a (complex) fluid a direct relation between g-1 and the mean squared displacement of the particles > can be established. Let us note P(s) the probability density function (PDF) of the photon path length s. The relation can be written as follows:
with and is the transport mean free path of scattered light.
For simple cell geometries, it is thus possible to calculate the mean squared displacement of the particles > from the measured g-1 values analytically. For example, for the backscattering geometry, an infinitely thick cell, large laser spot illumination and detection of photons coming from the center of the spot, the relationship between g-1 and > is:
, γ value is around 2.
For less thick cells and in transmission, the relationship depends also on l* (the transport length).
For quasi-transparent cells, an angle-independent variant method called cavity amplified scattering spectroscopy makes use of an integrating sphere to isotropically probe samples from all directions, elongating photon paths through the sample in the process, allowing for the study of low turbidity samples under the DWS formalism. | 0 | Theoretical and Fundamental Chemistry |
Perfusion-weighted imaging (PWI) is performed by 3 main techniques:
* Dynamic susceptibility contrast (DSC): Gadolinium contrast is injected, and rapid repeated imaging (generally gradient-echo echo-planar T2 weighted) quantifies susceptibility-induced signal loss.
* Dynamic contrast enhanced (DCE): Measuring shortening of the spin–lattice relaxation (T1) induced by a gadolinium contrast bolus.
* Arterial spin labelling (ASL): Magnetic labeling of arterial blood below the imaging slab, without the need of gadolinium contrast.
The acquired data is then postprocessed to obtain perfusion maps with different parameters, such as BV (blood volume), BF (blood flow), MTT (mean transit time) and TTP (time to peak).
In cerebral infarction, the penumbra has decreased perfusion. Another MRI sequence, diffusion-weighted MRI, estimates the amount of tissue that is already necrotic, and the combination of those sequences can therefore be used to estimate the amount of brain tissue that is salvageable by thrombolysis and/or thrombectomy. | 0 | Theoretical and Fundamental Chemistry |
Alessio Zaccone and collaborators investigated the effects of shear-flow on particle aggregation which can play an important role in applications e.g. microfluidics, chemical reactors, atmospheric and environmental flows. Their work showed a characteristic lag-time in the shear-induced aggregation of the particles, which decreases exponentially with the shear rate. | 0 | Theoretical and Fundamental Chemistry |
Barluenga was born in Tardienta (Huesca), Spain, where he spent his childhood and attended primary school.
He studied chemistry at the University of Zaragoza (B.Sc., 1963; Ph.D. 1966) with Professor V. Gómez Aranda. In 1967, he moved to Germany and, after a postdoctoral appointment at the Max-Planck Institut für Kohlenforschung in Mülheim an der Ruhr (1967–1970, Professor H. Hoberg), he returned to Spain to hold research positions at the Spanish Council for Scientific Research in Zaragoza (1970–1972) and University of Zaragoza (1972–1975). | 0 | Theoretical and Fundamental Chemistry |
Catabolite repression was extensively studied in Escherichia coli. E. coli grows faster on glucose than on any other carbon source. For example, if E. coli is placed on an agar plate containing only glucose and lactose, the bacteria will use glucose first and lactose second. When glucose is available in the environment, the synthesis of β-galactosidase is under repression due to the effect of catabolite repression caused by glucose. The catabolite repression in this case is achieved through the utilization of phosphotransferase system.
An important enzyme from the phosphotransferase system called Enzyme II A (EIIA) plays a central role in this mechanism. There are different catabolite-specific EIIA in a single cell, even though different bacterial groups have specificities to different sets of catabolites. In enteric bacteria one of the EIIA enzymes in their set is specific for glucose transport only. When glucose levels are high inside the bacteria, EIIA mostly exists in its unphosphorylated form. This leads to inhibition of adenylyl cyclase and lactose permease, therefore cAMP levels are low and lactose can not be transported inside the bacteria.
Once the glucose is all used up, the second preferred carbon source (i.e. lactose) has to be used by bacteria. Absence of glucose will "turn off" catabolite repression. When glucose levels are low, the phosphorylated form of EIIA accumulates and consequently activates the enzyme adenylyl cyclase, which will produce high levels of cAMP. cAMP binds to catabolite activator protein (CAP) and together they will bind to a promoter sequence on the lac operon. However, this is not enough for the lactose genes to be transcribed. Lactose must be present inside the cell to remove the lactose repressor from the operator sequence (transcriptional regulation). When these two conditions are satisfied, it means for the bacteria that glucose is absent and lactose is available. Next, bacteria start to transcribe the lac operon and produce β-galactosidase enzymes for lactose metabolism. The example above is a simplification of a complex process. Catabolite repression is considered to be a part of global control system and therefore it affects more genes rather than just lactose gene transcription. | 1 | Applied and Interdisciplinary Chemistry |
The two forms of inorganic arsenic, reduced (trivalent As(III)) and oxidized (pentavalent As(V)), can be absorbed, and accumulated in tissues and body fluids. In the liver, the metabolism of arsenic involves enzymatic and non-enzymatic methylation; the most frequently excreted metabolite (≥ 90%) in the urine of mammals is dimethylarsinic acid or cacodylic acid, DMA(V). Dimethylarsenic acid is also known as Agent Blue and was used as herbicide in the American war in Vietnam.
In humans inorganic arsenic is reduced nonenzymatically from pentoxide to trioxide, using glutathione or it is mediated by enzymes. Reduction of arsenic pentoxide to arsenic trioxide increases its toxicity and bio availability, Methylation occurs through methyltransferase enzymes. S-adenosylmethionine (SAM) may serve as methyl donor. Various pathways are used, the principal route being dependent on the current environment of the cell. Resulting metabolites are monomethylarsonous acid, MMA(III), and dimethylarsinous acid, DMA(III).
Methylation had been regarded as a detoxification process, but reduction from +5 As to +3 As may be considered as a bioactivation instead. Another suggestion is that methylation might be a detoxification if "As[III] intermediates are not permitted to accumulate" because the pentavalent organoarsenics have a lower affinity to thiol groups than inorganic pentavalent arsenics. Gebel (2002) stated that methylation is a detoxification through accelerated excretion. With regard to carcinogenicity it has been suggested that methylation should be regarded as a toxification.
Arsenic, especially +3 As, binds to single, but with higher affinity to vicinal sulfhydryl groups, thus reacts with a variety of proteins and inhibits their activity. It was also proposed that binding of arsenite at nonessential sites might contribute to detoxification. Arsenite inhibits members of the disulfide oxidoreductase family like glutathione reductase and thioredoxin reductase.
The remaining unbound arsenic (≤ 10%) accumulates in cells, which over time may lead to skin, bladder, kidney, liver, lung, and prostate cancers. Other forms of arsenic toxicity in humans have been observed in blood, bone marrow, cardiac, central nervous system, gastrointestinal, gonadal, kidney, liver, pancreatic, and skin tissues.
The acute minimal lethal dose of arsenic in adults is estimated to be 70 to 200 mg or 1 mg/kg/day. | 1 | Applied and Interdisciplinary Chemistry |
Newly created network of canals opens up new routes and ways of water navigation, which is generally more efficient and cheaper compared to road transport. | 1 | Applied and Interdisciplinary Chemistry |
Like all known forms of matter, liquids are fundamentally quantum mechanical. However, under standard conditions (near room temperature and pressure), much of the macroscopic behavior of liquids can be understood in terms of classical mechanics. The "classical picture" posits that the constituent molecules are discrete entities that interact through intermolecular forces according to Newton's laws of motion. As a result, their macroscopic properties can be described using classical statistical mechanics. While the intermolecular force law technically derives from quantum mechanics, it is usually understood as a model input to classical theory, obtained either from a fit to experimental data or from the classical limit of a quantum mechanical description. An illustrative, though highly simplified example is a collection of spherical molecules interacting through a Lennard-Jones potential.
For the classical limit to apply, a necessary condition is that the thermal de Broglie wavelength,
is small compared with the length scale under consideration. Here, is the Planck constant and is the molecule's mass. Typical values of are about 0.01-0.1 nanometers (Table 1). Hence, a high-resolution model of liquid structure at the nanoscale may require quantum mechanical considerations. A notable example is hydrogen bonding in associated liquids like water, where, due to the small mass of the proton, inherently quantum effects such as zero-point motion and tunneling are important.
For a liquid to behave classically at the macroscopic level, must be small compared with the average distance
between molecules. That is,
Representative values of this ratio for a few liquids are given in Table 1. The conclusion is that quantum effects are important for liquids at low temperatures and with small molecular mass. For dynamic processes, there is an additional timescale constraint:
where is the timescale of the process under consideration. For room-temperature liquids, the right-hand side is about 10 seconds, which generally means that time-dependent processes involving translational motion can be described classically.
At extremely low temperatures, even the macroscopic behavior of certain liquids deviates from classical mechanics. Notable examples are hydrogen and helium. Due to their low temperature and mass, such liquids have a thermal de Broglie wavelength comparable to the average distance between molecules. | 0 | Theoretical and Fundamental Chemistry |
The Purnell equation is an equation used in analytical chemistry to calculate the resolution R between two peaks in a chromatogram.
where
::R is the resolution between the two peaks
::N is the plate number of the second peak
::α is the separation factor between the two peaks
::k ' is the retention factor of the second peak.
The higher the resolution, the better the separation. | 0 | Theoretical and Fundamental Chemistry |
Friction stir processing (FSP) is a method of changing the properties of a metal through intense, localized plastic deformation. This deformation is produced by forcibly inserting a non-consumable tool into the workpiece, and revolving the tool in a stirring motion as it is pushed laterally through the workpiece. The precursor of this technique, friction stir welding, is used to join multiple pieces of metal without creating the heat affected zone typical of fusion welding.
When ideally implemented, this process mixes the material without changing the phase (by melting or otherwise) and creates a microstructure with fine, equiaxed grains. This homogeneous grain structure, separated by high-angle boundaries, allows some aluminium alloys to take on superplastic properties. Friction stir processing also enhances the tensile strength and fatigue strength of the metal. In tests with actively cooled magnesium-alloy workpieces, the microhardness was almost tripled in the area of the friction stir processed seam (to 120–130 Vickers hardness). | 1 | Applied and Interdisciplinary Chemistry |
Ulrike Diebold is well known for her influential work in the fields of surface science, materials and physical chemistry, and condensed matter physics. In particular, she has contributed greatly to the understanding of atomic-scale surface structure and electronic surface structure of metal oxides. For her work, she mainly employs Ultra-high vacuum technology and Scanning Tunneling Microscopy. | 0 | Theoretical and Fundamental Chemistry |
In 1994 Leonard Adleman presented the first prototype of a DNA computer. The TT-100 was a test tube filled with 100 microliters of a DNA solution. He managed to solve an instance of the directed Hamiltonian path problem. In Adlemans experiment, the Hamiltonian Path Problem was implemented notationally as the "travelling salesman problem". For this purpose, different DNA fragments were created, each one of them representing a city that had to be visited. Every one of these fragments is capable of a linkage with the other fragments created. These DNA fragments were produced and mixed in a test tube. Within seconds, the small fragments form bigger ones, representing the different travel routes. Through a chemical reaction, the DNA fragments representing the longer routes were eliminated. The remains are the solution to the problem, but overall, the experiment lasted a week. However, current technical limitations prevent the evaluation of the results. Therefore, the experiment isnt suitable for the application, but it is nevertheless a proof of concept. | 1 | Applied and Interdisciplinary Chemistry |
In metallurgy, non-ferrous metals are metals or alloys that do not contain iron (allotropes of iron, ferrite, and so on) in appreciable amounts.
Generally more costly than ferrous metals, non-ferrous metals are used because of desirable properties such as low weight (e.g. aluminium), higher conductivity (e.g. copper), non-magnetic properties or resistance to corrosion (e.g. zinc). Some non-ferrous materials are also used in the iron and steel industries. For example, bauxite is used as flux for blast furnaces, while others such as wolframite, pyrolusite, and chromite are used in making ferrous alloys.
Important non-ferrous metals include aluminium, copper, lead, tin, titanium, and zinc, and alloys such as brass. Precious metals such as gold, silver, and platinum and exotic or rare metals such as mercury, tungsten, beryllium, bismuth, cerium, cadmium, niobium, indium, gallium, germanium, lithium, selenium, tantalum, tellurium, vanadium, and zirconium are also non-ferrous. They are usually obtained through minerals such as sulfides, carbonates, and silicates. Non-ferrous metals are usually refined through electrolysis. | 1 | Applied and Interdisciplinary Chemistry |
Printing quality is highly influenced by the various treatments and methods used in creating paper and enhancing the paper surface. Consumers are most concerned with the paper-ink interactions which vary for certain types of paper due to different chemical properties of the surface. Inkjet paper is the most commercially used type of paper. Filter paper is another key type of paper whose surface chemistry affects its various forms and uses. The ability of adhesives to bond to a paper surface is also affected by the surface chemistry. | 0 | Theoretical and Fundamental Chemistry |
For hydrocarbons, the DBE (or IHD) tells us the number of rings and/or extra bonds in a non-saturated structure, which equals the number of hydrogen pairs that are required to make the structure saturated, simply because joining two elements to form a ring or adding one extra bond (e.g., a single bond changed to a double bond) in a structure reduces the need for two Hs. For non-hydrocarbons, the elements in a pair can include any elements in the lithium family and the fluorine family in the periodic table, not necessarily all Hs.
A popular form of the formula is as follows:
where , , and represent the number of carbon, nitrogen, hydrogen and halogen atoms, respectively. Each of the terms on the RHS can be explained, respectively, as follows:
*Except for the terminal carbons, every carbon chained to the structure with two single bonds requires a pair of hydrogen atoms attached to it. The number of carbons in the formula actually represents the number of hydrogen pairs required for that number of carbons to form a saturated structure. (This is also true if a carbon is added to the structure, whether it is inserted into a backbone chain, attached to a terminal to replace a hydrogen, or branched out from a carbon to replace a hydrogen.)
*Each of the two terminal carbons in the backbone chain needs one extra hydrogen – that is why "1" is added to the formula. (A branchs terminal doesnt need an H added in the calculation because the H replaced by the brunch can be counted as the H added to the brunch terminal. This is also true for a branch terminated with any element.)
*Except the terminal nitrogens, each nitrogen in the chain only requires one H attached to it, which is half a pair of hydrogens—that is why is in the formula, which gives a value of 1 for every two nitrogens. (This is also true if nitrogen is added into the structure, whether it is inserted into a backbone chain, attached to a terminal to replace an H, or branched out from a C to replace an H.)
*The represents the number of hydrogen pairs because it gives a value of 1 for every two hydrogen atoms. It is subtracted in the formula to count how many pairs of hydrogen atoms are missing in the unsaturated structure, which tells us the degree of hydrogen deficiency. (No hydrogen pair is missing if , which corresponds to no hydrogen deficiency.)
*The presence of is for a reason similar to .
Adding an oxygen atom to the structure requires no hydrogen added, which is why the number of oxygen atoms does not appear in the formula.
Furthermore, the formula can be generalised to include all elements of Group I (the hydrogen and lithium family), Group IV (the carbon family), Group V (the nitrogen family) and Group VII (the fluorine family) of CAS A group in the periodic table as follows:
Or simply, | 0 | Theoretical and Fundamental Chemistry |
The mechanism of the Cornforth rearrangement begins by a thermal pericyclic ring opening which furnishes a nitrile intermediate 1, which then undergoes rearrangement to the oxazole, which is isomeric to the starting compound.
The ylide intermediate has several resonance contributors and the stability of said structures affects the outcome of the reaction, since the intermediate will revert to the starting material if the third resonance structure is most stable. Whether the reaction takes place is dependent on the energy difference between the starting material and the product. | 0 | Theoretical and Fundamental Chemistry |
Potentiometric titrimetry has been the predominant automated titrimetric technique since the 1970s, so it is worthwhile considering the basic differences between it and thermometric titrimetry.
Potentiometrically-sensed titrations rely on a free energy change in the reaction system. Measurement of a free energy dependent term is necessary.
: ΔG = -RT lnK (1)
Where:
: ΔG = change on free energy
: R = universal gas constant
: T = temperature in kelvins (K) or degrees Rankine (°R)
: K = equilibrium constant at temperature T
: ln is the natural logarithm function
In order for a reaction to be amenable to potentiometric titrimetry, the free energy change must be sufficient for an appropriate sensor to respond with a significant inflection (or "kink") in the titration curve where sensor response is plotted against the amount of titrant delivered.
However, free energy is just one of three related parameters in describing any chemical reaction:
: ΔH = ΔG + TΔS (2)
where:
: ΔH = change in enthalpy
: ΔG = change in free energy
: ΔS = change in entropy
: T = temperature in K
For any reaction where the free energy is not opposed by the entropy change, the enthalpy change will be significantly greater than the free energy. Thus a titration based on a change in temperature (which permits observation of the enthalpy change) will show a greater inflection than will curves obtained from sensors reacting to free energy changes alone. | 0 | Theoretical and Fundamental Chemistry |
The third annual Empowering Women in Organic Chemistry Conference was held virtually on Thursday, June 24, and Friday, June 25, 2021.
2021 Career Panel featured Kay Brummond (Univ of Pittsburgh), Martha A. Sarpong (GlaxoSmithKline), Emma Radoux (Royal Society of Chemistry), Callie Bryan (Janssen), Kimberly Steward (Cargill) and Daisy Rosas Vargas (Ithaca College). | 0 | Theoretical and Fundamental Chemistry |
Population increase in India is the other driver of the need for river inter-linking. India's population growth rate has been falling but still continues to increase by about 10 to 15 million people every year. The resulting demand for food must be satisfied with higher yields and better crop security, both of which require adequate irrigation of about 140 million hectares of land. Currently, just a fraction of that land is irrigated, and most irrigation relies on monsoon. River interlinking is claimed to be a possible means of assured and better irrigation for more farmers, and thus better food security for a growing population. In a tropical country like India with high evapotranspiration, food security can be achieved with water security which in turn is achieved with energy security to pump water to uplands from water surplus lower elevation river points up to sea level. | 1 | Applied and Interdisciplinary Chemistry |
In insects, biliprotein lipocalins generally function to facilitate the changing of colours during camouflage, but other roles of biliproteins in insects have also been found. Functions such as preventing cellular damage, regulating guanylyl cyclase with biliverdin, among other roles associated with metabolic maintenance, have been hypothesised but yet to be proven. In the tobacco hornworm, the biliprotein insecticyanin (INS) was found to play a crucial part in embryonic development, as the absorption of INS into the moth eggs was observed. | 1 | Applied and Interdisciplinary Chemistry |
I-type lectin named from the immunoglobulin-like domain. Sialoadhesin is one of the I-type lectin, which binds specifically to sialic acid. | 0 | Theoretical and Fundamental Chemistry |
Amides are pervasive in nature and technology. Proteins and important plastics like Nylons, Aramid, Twaron, and Kevlar are polymers whose units are connected by amide groups (polyamides); these linkages are easily formed, confer structural rigidity, and resist hydrolysis. Amides include many other important biological compounds, as well as many drugs like paracetamol, penicillin and LSD. Low-molecular-weight amides, such as dimethylformamide, are common solvents. | 0 | Theoretical and Fundamental Chemistry |
* halocarbonates, including carbonate fluorides, carbonate chlorides, carbonate bromides
* phosphates, including fluoride phosphates, chloride phosphate, phosphate molybdates, phosphate arsenates
* borates
** halide borates, including fluoride borates borate chlorides, borate bromides, borate iodides
** chalcogenide borates, including sulfide borates
** borate carbonates, borate nitrates, borate sulfates, borate phosphates
** borate acetates
** Condensed borates: borosulfates, boroselenates, borotellurates, boroantimonates, borophosphates, boroselenites
* sulfates
** sulfate fluorides, sulfate chlorides
** sulfate arsenate
* selenite fluorides
* iodate fluorides
* Silicates
** sulfide silicates | 0 | Theoretical and Fundamental Chemistry |
The active site of PLE facilitates both substrate binding and hydrolysis. A key serine residue in the active site promotes hydrolysis, but the substrate must present an ester group to this residue after binding to the enzyme active site for hydrolysis to take place. Whether the substrate is able to present an ester group to the catalytic serine residue depends on its bound conformation in the active site, which is dictated by amino acid side-chains in the active site. Thus, active site models of PLE have been advanced with the goal of predicting from the structure of the substrate which of two enantiotopic ester groups will be hydrolyzed (or whether hydrolysis is likely to occur at all).
A simple model for the binding conformation of an ester in the active site of PLE is shown below. This model accurately predicts the configuration of hydrolyzed glutarates and similar substrates. | 0 | Theoretical and Fundamental Chemistry |
Purines are biologically synthesized as nucleotides and in particular as ribotides, i.e. bases attached to ribose 5-phosphate. Both adenine and guanine are derived from the nucleotide inosine monophosphate (IMP), which is the first compound in the pathway to have a completely formed purine ring system. | 1 | Applied and Interdisciplinary Chemistry |
The silver nanoparticles that pass through wastewater treatment plants undergo transformations in the environment through changes in aggregation state, oxidation state, precipitation of secondary phases, or sorption of organic species. These transformations can result in the formation of colloidal solutions. Each of these new species potentially have toxic effects which have yet to be fully examined.
Most silver nanoparticles in products have an organic shell structure around a core of Ag. This shell is often created with carboxylic acids functional groups, usually using citrate, leading to stabilization through adsorption or covalent attachment of organic compounds. In seawater, glutathione reacts with citrate to form a thioester via esterification.
Thioesters exhibit electrosteric repulsive forces due to amine functional groups and their size, which prevents aggregation. These electrostatic repulsive forces are weakened by counterions in solution, such as Ca found in seawater. Ca ions are naturally found in seawater due to the weathering of calcareous rocks, and allow for dissolution of the oxide-coated particle at low electrolyte concentrations.
This leads to the aggregation of silver nanoparticles onto thioesters in seawater. When aggregation occurs, the silver nanoparticles lose microbial toxicity, but have greater exposure in the environment for larger organisms. These effects have not been completely identified, but may be hazardous to an organism’s health via biological magnification. | 1 | Applied and Interdisciplinary Chemistry |
The triose phosphate translocator is an integral membrane protein found in the inner membrane of chloroplasts. It exports triose phosphate (Dihydroxyacetone phosphate) in exchange for inorganic phosphate and is therefore classified as an antiporter. The imported phosphate is then used for ATP regeneration via the light-dependent-reaction; the ATP may then for example be used for further reactions in the Calvin-cycle. The translocator protein is responsible for exporting all the carbohydrate produced in photosynthesis by plants and therefore most of the carbon in food that one eats has been transported by the triose phosphate translocator. Its three-dimensional structure was reported in 2017, revealing how it recognizes two different substrates to catalyze the strict 1:1 exchange. | 0 | Theoretical and Fundamental Chemistry |
The use of racemic amlodipine is commonly associated with adverse events like peripheral edema and other side effects like headache, dizziness, flushing and abdominal pain. Controlled clinical trials showed that levamlodipine is rarely associated with these side effects. No controlled clinical study of levamlodipine has been performed in patients with hepatic impairment and renal impairment. Clinical studies in patients with normal liver function have shown that there is no elevation in the hepatic enzymes with the use of levamlodipine. However, caution should be taken while administering levamlodipine to such patients.
In a postmarketing surveillance study, levamlodipine (2.5/5 mg) was found to be well tolerated (n = 1859) in patients with hypertension. Out of 314 patients, who reported peripheral edema with conventional amlodipine were switched over to levamlodipine and edema was resolved in 310 patients (98.72%) at the end of 4 weeks. Only in 4 patients was edema sustained. Only 30 patients (out of 1859) reported side effects. These side effects included vertigo, tachycardia, cough, headache, fever, mild difficulty in breathing and edema. Adverse events were mild in nature and no serious adverse events were reported. | 0 | Theoretical and Fundamental Chemistry |
Much of what are known as Isaac Newtons occult studies can largely be attributed to his study of alchemy. From a young age, Newton was deeply interested in all forms of natural sciences and materials science, an interest which would ultimately lead to some of his better-known contributions to science. His earliest encounters with certain alchemical theories and practices were during his childhood, when a twelve year old Isaac Newton was boarding in the attic of an apothecaries shop. During Newtons lifetime, the study of chemistry was still in its infancy, so many of his experimental studies used esoteric language and vague terminology more typically associated with alchemy and occultism. It was not until several decades after Newtons death that experiments of stoichiometry under the pioneering works of Antoine Lavoisier were conducted, and analytical chemistry, with its associated nomenclature, came to resemble modern chemistry as we know it today. However, Newtons contemporary and fellow Royal Society member, Robert Boyle, had already discovered the basic concepts of modern chemistry and began establishing modern norms of experimental practice and communication in chemistry, information which Newton did not use.
Much of Newton's writing on alchemy may have been lost in a fire in his laboratory, so the true extent of his work in this area may have been larger than is currently known. Newton also suffered a nervous breakdown during his period of alchemical work.
Newtons writings suggest that one of the main goals of his alchemy may have been the discovery of the philosophers stone (a material believed to turn base metals into gold), and perhaps to a lesser extent, the discovery of the highly coveted Elixir of Life. Newton reportedly believed that a Diana's Tree, an alchemical demonstration producing a dendritic "growth" of silver from solution, was evidence that metals "possessed a sort of life."
Some practices of alchemy were banned in England during Newton's lifetime, due in part to unscrupulous practitioners who would often promise wealthy benefactors unrealistic results in an attempt to swindle them. The English Crown, also fearing the potential devaluation of gold because of the creation of fake gold, made penalties for alchemy very severe. In some cases the punishment for unsanctioned alchemy would include the public hanging of an offender on a gilded scaffold while adorned with tinsel and other items. | 1 | Applied and Interdisciplinary Chemistry |
Benefits will be realised by pursuing two overarching goals:
* To determine global ocean distributions of selected trace elements and isotopes, and to evaluate the sources, sinks, and internal cycling of these species in order to characterise more completely the physical, chemical and biological processes regulating their distributions.
* To understand the response of trace element and isotope cycles to global change, to help predict the future and to improve chemical proxies for past changes in the ocean environment. | 0 | Theoretical and Fundamental Chemistry |
Electron diffraction measurements of the vapour at 255 K established that digallane is structurally similar to diborane with 2 bridging hydrogen atoms (so-called three-center two-electron bonds). The terminal Ga-H bond length is 152 pm, the Ga-H bridging is 171 pm and the Ga-H-Ga angle is 98°. The Ga-Ga distance is 258 pm. The H NMR spectrum of a solution of digallane in toluene shows two peaks attributable to terminal and bridging hydrogen atoms.
In the solid state, digallane appears to adopt a polymeric or oligomeric structure. The vibrational spectrum is consistent with tetramer (i.e. ). The vibrational data indicate the presence of terminal hydride ligands. In contrast, the hydrogen atoms are all bridging in α-alane, a high-melting, relatively stable polymeric form of aluminium hydride wherein the aluminium centers are 6-coordinated. Digallane decomposes at ambient temperatures: | 0 | Theoretical and Fundamental Chemistry |
Isotope analysis is the identification of isotopic signature, abundance of certain stable isotopes of chemical elements within organic and inorganic compounds. Isotopic analysis can be used to understand the flow of energy through a food web, to reconstruct past environmental and climatic conditions, to investigate human and animal diets, for food authentification, and a variety of other physical, geological, palaeontological and chemical processes. Stable isotope ratios are measured using mass spectrometry, which separates the different isotopes of an element on the basis of their mass-to-charge ratio. | 0 | Theoretical and Fundamental Chemistry |
If the solvent is a liquid, then almost all gases, liquids, and solids can be dissolved. Here are some examples:
* Gas in liquid:
** Oxygen in water
** Carbon dioxide in water – a less simple example, because the solution is accompanied by a chemical reaction (formation of ions). The visible bubbles in carbonated water are not the dissolved gas, but only an effervescence of carbon dioxide that has come out of solution; the dissolved gas itself is not visible since it is dissolved on a molecular level.
* Liquid in liquid:
** The mixing of two or more substances of the same chemistry but different concentrations to form a constant. (Homogenization of solutions)
** Alcoholic beverages are basically solutions of ethanol in water.
* Solid in liquid:
** Sucrose (table sugar) in water
** Sodium chloride (NaCl) (table salt) or any other salt in water, which forms an electrolyte: When dissolving, salt dissociates into ions.
* Solutions in water are especially common, and are called aqueous solutions.
* Non-aqueous solutions are when the liquid solvent involved is not water.
Counterexamples are provided by liquid mixtures that are not homogeneous: colloids, suspensions, emulsions are not considered solutions.
Body fluids are examples of complex liquid solutions, containing many solutes. Many of these are electrolytes since they contain solute ions, such as potassium. Furthermore, they contain solute molecules like sugar and urea. Oxygen and carbon dioxide are also essential components of blood chemistry, where significant changes in their concentrations may be a sign of severe illness or injury. | 0 | Theoretical and Fundamental Chemistry |
A coordination complex is a chemical compound consisting of a central atom or ion, which is usually metallic and is called the coordination centre, and a surrounding array of bound molecules or ions, that are in turn known as ligands or complexing agents. Many metal-containing compounds, especially those that include transition metals (elements like titanium that belong to the periodic table's d-block), are coordination complexes. | 0 | Theoretical and Fundamental Chemistry |
Green roofs improve air and water quality while reducing energy cost. The implementation of green roofs in some regions have correlated with increased albedo, providing slightly cooler temperatures and thus, lower energy consumption.The plants and soil provide more green space and insulation on roofs. Green and blue roofs also help reducing city runoff by retaining rainfall providing a potential solution for the stormwater management in highly concentrated urban areas. The social benefit of green roofs is the rooftop agriculture for the residents.
Green roofs also sequester rain and carbon pollution. Forty to eighty percent of the total volume of rain that falls on green roofs are able to be reserved. The water released from the roofs flow at a slow pace, reducing the amount of runoff entering the watershed at once.
Blue roofs, not technically being green infrastructure, collect and store rainfall, reducing the inrush of runoff water into sewer systems. Blue roofs use detention ponds, or detention basins, for collecting the rainfall before it gets drained into waterways and sewers at a controlled rate. As well as saving energy by reducing cooling expenses, blue roofs reduce the urban heat island effect when coupled with reflective roofing material. | 1 | Applied and Interdisciplinary Chemistry |
Once the presence of a carbonyl group has been identified using 2,4-dinitrophenylhydrazine (also known as Bradys reagent or 2,4-DNPH or 2,4-DNP), Tollens reagent can be used to distinguish ketone vs aldehyde. Tollens' reagent gives a negative test for most ketones, with alpha-hydroxy ketones being one exception.
The test rests on the premise that aldehydes are more readily oxidized compared with ketones; this is due to the carbonyl-containing carbon in aldehydes having attached hydrogen. The diamine silver(I) complex in the mixture is an oxidizing agent and is the essential reactant in Tollens' reagent. The test is generally carried out in a test tube in a warm water bath.
In a positive test, the diamine silver(I) complex oxidizes the aldehyde to a carboxylate ion and in the process is reduced to elemental silver and aqueous ammonia. The elemental silver precipitates out of solution, occasionally onto the inner surface of the reaction vessel, giving a characteristic "silver mirror". The carboxylate ion on acidification will give its corresponding carboxylic acid. The carboxylic acid is not directly formed in the first place as the reaction takes place under alkaline conditions. The ionic equations for the overall reaction are shown below; R refers to an alkyl group.
Tollens' reagent can also be used to test for terminal alkynes (). A white precipitate of the acetylide () is formed in this case. Another test relies on reaction of the furfural with phloroglucinol to produce a colored compound with high molar absorptivity. It also gives a positive test with hydrazines, hydrazones, α-hydroxy ketones and 1,2-dicarbonyls.
Both Tollens reagent and Fehlings reagent give positive results with formic acid. | 0 | Theoretical and Fundamental Chemistry |
Admissions are carried out on an All-India basis and the students are drawn from different parts of the country.
To prepare trained Chemist Scientists for positions in drug and pharmaceutical industries and environmental organizations, School is running many courses in pharmaceutical sciences.
M. Sc. (Pharmaceutical Chemistry)<br>
M. Sc. (Applied Chemistry)<br>
M. Sc. (Chemistry)<br /> | 1 | Applied and Interdisciplinary Chemistry |
Direct effects of increasing CO concentrations in the atmosphere include increasing global temperatures, ocean acidification and a CO fertilization effect on plants and crops. | 1 | Applied and Interdisciplinary Chemistry |
This method use DNA recombinant technology and it gives an actual measurement of protein stability. In his detailed site-directed mutagenesis studies, Utani and his coworkers substituted 19 amino acids at Trp49 of the tryptophan synthase and he measured the free energy of unfolding. They found that the increased stability is directly proportional to increase in hydrophobicity up to a certain size limit. The main disadvantage of site-directed mutagenesis method is that not all the 20 naturally occurring amino acids can substitute a single residue in a protein. Moreover, these methods have cost problems and is useful only for measuring protein stability. | 0 | Theoretical and Fundamental Chemistry |
Chiral crown stationary phases consist Crown ethers, immobilized or bonded to the support particles, are polyethers with a macrocyclic structure that can create host-guest complexes with alkali, earth-alkali metal ions, and ammonium cations. The skeleton of the cyclic structure is composed of oxygen and methylene groups arranged alternately. The electron-donating ether oxygens are positioned within the inner wall of the crown cavity, and are encircled by methylene groups in a collar-like arrangement. The chiral recognition is based on two distinct diastereomeric inclusion complexes that can be generated. The primary interactions facilitating complexation involve hydrogen bonds, formed between the three amine hydrogens and the oxygens of the macrocyclic ether, arranged in a tripod configuration. Additionally, ionic interactions, dipole-dipole interactions, or hydrogen bonds can occur between the carbocyclic groups and polar groups of the analytes, providing further support for the complexes. | 0 | Theoretical and Fundamental Chemistry |
The history of biochemistry can be said to have started with the ancient Greeks who were interested in the composition and processes of life, although biochemistry as a specific scientific discipline has its beginning around the early 19th century. Some argued that the beginning of biochemistry may have been the discovery of the first enzyme, diastase (today called amylase), in 1833 by Anselme Payen, while others considered Eduard Buchners first demonstration of a complex biochemical process alcoholic fermentation in cell-free extracts to be the birth of biochemistry. Some might also point to the influential work of Justus von Liebig from 1842, Animal chemistry, or, Organic chemistry in its applications to physiology and pathology', which presented a chemical theory of metabolism, or even earlier to the 18th century studies on fermentation and respiration by Antoine Lavoisier.
The term biochemistry itself is derived from the combining form bio-, meaning life, and chemistry. The word is first recorded in English in 1848, while in 1877, Felix Hoppe-Seyler used the term ( in German) in the foreword to the first issue of Zeitschrift für Physiologische Chemie (Journal of Physiological Chemistry) as a synonym for physiological chemistry and argued for the setting up of institutes dedicate to its studies. Nevertheless, several sources cite German chemist Carl Neuberg as having coined the term for the new discipline in 1903, and some credit it to Franz Hofmeister.
The subject of study in biochemistry is the chemical processes in living organisms, and its history involves the discovery and understanding of the complex components of life and the elucidation of pathways of biochemical processes. Much of biochemistry deals with the structures and functions of cellular components such as proteins, carbohydrates, lipids, nucleic acids and other biomolecules; their metabolic pathways and flow of chemical energy through metabolism; how biological molecules give rise to the processes that occur within living cells; it also focuses on the biochemical processes involved in the control of information flow through biochemical signalling, and how they relate to the functioning of whole organisms. Over the last 40 years the field has had success in explaining living processes such that now almost all areas of the life sciences from botany to medicine are engaged in biochemical research.
Among the vast number of different biomolecules, many are complex and large molecules (called polymers), which are composed of similar repeating subunits (called monomers). Each class of polymeric biomolecule has a different set of subunit types. For example, a protein is a polymer whose subunits are selected from a set of twenty or more amino acids, carbohydrates are formed from sugars known as monosaccharides, oligosaccharides, and polysaccharides, lipids are formed from fatty acids and glycerols, and nucleic acids are formed from nucleotides. Biochemistry studies the chemical properties of important biological molecules, like proteins, and in particular the chemistry of enzyme-catalyzed reactions. The biochemistry of cell metabolism and the endocrine system has been extensively described. Other areas of biochemistry include the genetic code (DNA, RNA), protein synthesis, cell membrane transport, and signal transduction. | 1 | Applied and Interdisciplinary Chemistry |
Cadmium is a strong neutron poison and in fact control rods are often made out of cadmium, making the accumulation of cadmium in fuel of particular concern for the maintenance of stable neutron economy. Cadmium is also a chemically poisonous heavy metal, but given the number of neutron absorptions required for transmutation, it is not a high priority target for deliberate transmutation. | 0 | Theoretical and Fundamental Chemistry |
In quantum mechanics, a doublet is a composite quantum state of a system with an effective spin of 1/2, such that there are two allowed values of the spin component, −1/2 and +1/2. Quantum systems with two possible states are sometimes called two-level systems. Essentially all occurrences of doublets in nature arise from rotational symmetry; spin 1/2 is associated with the fundamental representation of the Lie group SU(2). | 0 | Theoretical and Fundamental Chemistry |
In a body submerged in a fluid, unsteady forces due to acceleration of that body with respect to the fluid, can be divided into two parts: the virtual mass effect and the Basset force.
The Basset force term describes the force due to the lagging boundary layer development with changing relative velocity (acceleration) of bodies moving through a fluid.
The Basset term accounts for viscous effects and addresses the temporal delay in boundary layer development as the relative velocity changes with time. It is also known as the "history" term.
The Basset force is difficult to implement and is commonly neglected for practical reasons; however, it can be substantially large when the body is accelerated at a high rate.
This force in an accelerating Stokes flow has been proposed by Joseph Valentin Boussinesq in 1885 and Alfred Barnard Basset in 1888. Consequently, it is also referred to as the Boussinesq–Basset force. | 1 | Applied and Interdisciplinary Chemistry |
Materials science has shaped the development of civilizations since the dawn of humankind. Better materials for tools and weapons has allowed people to spread and conquer, and advancements in material processing like steel and aluminum production continue to impact society today. Historians have regarded materials as such an important aspect of civilizations such that entire periods of time have defined by the predominant material used (Stone Age, Bronze Age, Iron Age). For most of recorded history, control of materials had been through alchemy or empirical means at best. The study and development of chemistry and physics assisted the study of materials, and eventually the interdisciplinary study of materials science emerged from the fusion of these studies. The history of materials science is the study of how different materials were used and developed through the history of Earth and how those materials affected the culture of the peoples of the Earth. The term "Silicon Age" is sometimes used to refer to the modern period of history during the late 20th to early 21st centuries. | 1 | Applied and Interdisciplinary Chemistry |
Some derivatives that were designed to penetrate mitochondrial cell membranes (SkQ1 (plastoquinonyl-decyl-triphenylphosphonium), SkQR1 (the rhodamine-containing analog of SkQ1), SkQ3) have anti-oxidant and protonophore activity. SkQ1 has been proposed as an anti-aging treatment, with the possible reduction of age-related vision issues due to its antioxidant ability. This antioxidant ability results from both its antioxidant ability to reduce reactive oxygen species (derived from the part of the molecule containing plastoquinonol), which are often formed within mitochondria, as well as its ability to increase ion exchange across membranes (derived from the part of the molecule containing cations that can dissolve within membranes). Specifically, like plastoquinol, SkQ1 has been shown to scavenge superoxides both within cells (in vivo) and outside of cells (in vitro). SkQR1 and SkQ1 have also been proposed as a possible way to treat brain issues like Alzheimer's due to their ability to potentially fix damages caused by amyloid beta. Additionally, SkQR1 has been shown as a way to reduce the issues caused by brain trauma through its antioxidant abilities, which help prevent cell death signals by reducing the amounts of reactive oxygen species coming from mitochondria. | 0 | Theoretical and Fundamental Chemistry |
Unlike its human ortholog, murine perilipin is composed of 517 amino acids in the primary structure of which several regions can be identified. Three moderately hydrophobic sequences (H1, H2, H3) of 18 rem (243-260 aa), 23 rem (320-332 aa) and 16 rem (349-364 aa) can be identified in the centre of the protein, as well as an acidic region of 28 residues where both glutamic and aspartic acids add up to 19 of them. Five sequences 18 residues long that could form amphipathic β-pleated sheets—according to a prediction made through LOCATE program—are found between aa 111 and 182. Serines occupying positions 81, 222, 276, 433, 492 and 517 act as phosphorylation sites -numbered from 1 to 6- for PKA, as well as several other threonines and serines which add up to 27 phosphorylation sites. | 1 | Applied and Interdisciplinary Chemistry |
Hansen solubility parameters were developed by Charles M. Hansen in his Ph.D thesis in 1967 as a way of predicting if one material will dissolve in another and form a solution. They are based on the idea that like dissolves like where one molecule is defined as being like another if it bonds to itself in a similar way.
Specifically, each molecule is given three Hansen parameters, each generally measured in MPa:
* The energy from dispersion forces between molecules
* The energy from dipolar intermolecular forces between molecules
* The energy from hydrogen bonds between molecules.
These three parameters can be treated as co-ordinates for a point in three dimensions also known as the Hansen space. The nearer two molecules are in this three-dimensional space, the more likely they are to dissolve into each other. To determine if the parameters of two molecules (usually a solvent and a polymer) are within range, a value called interaction radius () is given to the substance being dissolved. This value determines the radius of the sphere in Hansen space and its center is the three Hansen parameters. To calculate the distance () between Hansen parameters in Hansen space the following formula is used:
Combining this with the interaction radius gives the relative energy difference (RED) of the system:
* If the molecules are alike and will dissolve
* If the system will partially dissolve
* If the system will not dissolve | 0 | Theoretical and Fundamental Chemistry |
Cyclic Corrosion Testing (CCT) has evolved in recent years, largely within the automotive industry, as a way of accelerating real-world corrosion failures, under laboratory controlled conditions.
As the name implies, the test comprises different climates which are cycled automatically so the samples under test undergo the same sort of changing environment that would be encountered in the natural world. The intention being to bring about the type of failure that might occur naturally, but more quickly i.e. accelerated. By doing this manufacturers and suppliers can predict, more accurately, the service life expectancy of their products.
Until the development of Cyclic Corrosion Testing, the traditional Salt spray test was virtually all that manufacturers could use for this purpose. However, this test was never intended for this purpose. Because the test conditions specified for salt spray testing are not typical of a naturally occurring environment, this type of test cannot be used as a reliable means of predicting the ‘real world’ service life expectancy for the samples under test. The sole purpose of the salt spray test is to compare and contrast results with previous experience to perform a quality audit. So, for example, a spray test can be used to ‘police’ a production process and forewarn of potential manufacturing problems or defects, which might affect corrosion resistance.
To recreate these different environments within an environmental chamber requires much more flexible testing procedures than are available in a standard salt spray chamber.
The lack of correlation between results obtained from traditional salt spray testing and the ‘real world’ atmospheric corrosion of vehicles, left the automotive industry without a reliable test method for predicting the service life expectancy of their products. This was and remains of particular concern in an industry where anti-corrosion warranties have been gradually increasing and now run to several years for new vehicles.
With ever increasing consumer pressure for improved vehicle corrosion resistance and a few ‘high profile’ corrosion failures amongst some vehicle manufactures – with disastrous commercial consequences, the automotive industry recognized the need for a different type of corrosion test.
Such a test would need to simulate the types of conditions a vehicle might encounter naturally, but recreate and accelerate these conditions, with good repeatability, within the convenience of the laboratory.
CCT is effective for evaluating a variety of corrosion types, including galvanic corrosion and crevice corrosion. One of the earliest introduced cyclic testing machines was the Prohesion cabinet. | 1 | Applied and Interdisciplinary Chemistry |
Because secondary structure of the 5’ end of mRNA influences translational efficiency, synonymous changes at this region on the mRNA can result in profound effects on gene expression. Codon usage in noncoding DNA regions can therefore play a major role in RNA secondary structure and downstream protein expression, which can undergo further selective pressures. In particular, strong secondary structure at the ribosome-binding site or initiation codon can inhibit translation, and mRNA folding at the 5’ end generates a large amount of variation in protein levels. | 1 | Applied and Interdisciplinary Chemistry |
Thermal degradation of DOC has been found at high-temperature hydrothermal ridge-flanks, where outflow DOC concentrations are lower than in the inflow. While the global impact of these processes has not been investigated, current data suggest it is a minor DOC sink. Abiotic DOC flocculation is often observed during rapid (minutes) shifts in salinity when fresh and marine waters mix. Flocculation changes the DOC chemical composition, by removing humic compounds and reducing molecular size, transforming DOC to particulate organic flocs which can sediment and/or be consumed by grazers and filter feeders, but it also stimulates the bacterial degradation of the flocculated DOC. The impacts of flocculation on the removal of DOC from coastal waters are highly variable with some studies suggesting it can remove up to 30% of the DOC pool, while others find much lower values (3–6%;). Such differences could be explained by seasonal and system differences in the DOC chemical composition, pH, metallic cation concentration, microbial reactivity, and ionic strength. | 1 | Applied and Interdisciplinary Chemistry |
In organometallic chemistry, agostic interaction refers to the interaction of a coordinatively-unsaturated transition metal with a C−H bond, when the two electrons involved in the C−H bond enter the empty d-orbital of the transition metal, resulting in a three-center two-electron bond. Many catalytic transformations, e.g. oxidative addition and reductive elimination, are proposed to proceed via intermediates featuring agostic interactions. Agostic interactions are observed throughout organometallic chemistry in alkyl, alkylidene, and polyenyl ligands. | 0 | Theoretical and Fundamental Chemistry |
SH2 domains are not present in yeast and appear at the boundary between protozoa and animalia in organisms such as the social amoeba Dictyostelium discoideum.
A detailed bioinformatic examination of SH2 domains of human and mouse reveals 120 SH2 domains contained within 115 proteins encoded by the human genome, representing a rapid rate of evolutionary expansion among the SH2 domains.
A large number of SH2 domain structures have been solved and many SH2 proteins have been knocked out in mice. | 1 | Applied and Interdisciplinary Chemistry |
Plants respond to injury by signalling that damage has occurred, by secreting materials to seal off the damaged area, by producing antimicrobials to limit the spread of pathogens, and in some woody plants by regrowing over the wound. | 1 | Applied and Interdisciplinary Chemistry |
Survivin is shown to be clearly regulated by the cell cycle, as its expression is found to be dominant only in the G2/M phase. This regulation exists at the transcriptional level, as there is evidence of the presence of cell-cycle-dependent element/cell-cycle gene homology region (CDE/CHR)boxes located in the survivin promoter region. Further evidence to support this mechanism of regulation includes the evidence that surivin is poly-ubiquinated and degraded by proteasomes during interphase of the cell cycle. Moreover, survivin has been shown to localize to components of the mitotic spindle during metaphase and anaphase of mitosis. Physical association between polymerized tubulin and survivin have been shown in vitro as well. It is also shown that post-transcriptional modification of survivin involving the phosphorylation of Thr34 leads to increased protein stability in the G2/M phase of the cell cycle.
It is known from Mirza et al. that repression of survivin by p53 is not a result of any cell cycle progressive regulation. The same experiment by Mirza et al. with regard to determining p53 suppression of survivin at the transcriptional level was repeated, but this time for cells arrested in different stages of the cell cycle. It was shown that, although p53 arrests the numbers of cells to different extents in different phases, the measured level of survivin mRNA and protein levels were the same across all the samples transfected with the wild-type p53. This shows that p53 acts in a cell-cycle independent manner to inhibit survivin expression. | 1 | Applied and Interdisciplinary Chemistry |
In materials science, paracrystalline materials are defined as having short- and medium-range ordering in their lattice (similar to the liquid crystal phases) but lacking crystal-like long-range ordering at least in one direction. | 0 | Theoretical and Fundamental Chemistry |
Diachylon (from Latin diachȳlōn, representing Greek , "[a medicament] composed of juices"), also rendered diachylum or diaculum, was originally a kind of medicament made of the juices of several plants (thus its name), but now commonly the name for lead-plaster, emplastrum plumbi—a plaster made of lead oxide boiled together with olive oil and water. It is applied to sheets of linen, and works as an adhesive plaster when heated.
Historically, several different types of diachylons have been described. White, or simple, diacyhlon is compounded of common oil, litharge of gold (litharge mixed with red lead), and adhesives drawn from the root of the Althaea, the seeds of flax and fenugreek. The diachylon called direatum has for its basis the common white diachylon, but with every pound of which is mixed an ounce of powder of Iris; this plaster digests, incides, and ripens with more force than the simple diachylon.
There is also the great diachylon, or diachylon magnum, composed of litharge of gold, oils of iris, chamomile, and aneth, turpentine, pine resin, yellow wax, and adhesives derived from flax, fenugreek, with new figs, raisins of Damascus, icthyocolla, juices of iris, squill, and hyssop. This diachylon was said to soften hard swellings called scirrhus, and dissipate tumors.
The diachylon gummatum is the great diachylon with the addition of gum ammoniac, galbanum, and sagapenum, dissolved with wine, and boiled to a consistency of honey. This plaster was believed the most power of all for digesting, ripening, and resolving. | 1 | Applied and Interdisciplinary Chemistry |
Consider fluid flow around an airfoil. The flow of the fluid around the airfoil gives rise to lift and drag forces. By definition, lift is the force that acts on the airfoil normal to the apparent fluid flow speed seen by the airfoil. Drag is the forces that acts tangential to the apparent fluid flow speed seen by the airfoil. What do we mean by an apparent speed? Consider the diagram below:
The speed seen by the rotor blade is dependent on three things: the axial velocity of the fluid, ; the tangential velocity of the fluid due to the acceleration round an airfoil, ; and the rotor motion itself, . That is, the apparent fluid velocity is given as below:
Thus the apparent wind speed is just the magnitude of this vector i.e.:
We can also work out the angle from the above figure:
Supposing we know the angle , we can then work out simply by using the relation ; we can then work out the lift co-efficient, , and the drag co-efficient , from which we can work out the lift and drag forces acting on the blade.
Consider the annular ring, which is partially occupied by blade elements. The length of each blade section occupying the annular ring is (see figure below).
The lift acting on those parts of the blades/airfoils each with chord is given by the following expression:
where is the lift co-efficient, which is a function of the angle of attack, and is the number of blades. Additionally, the drag acting on that part of the blades/airfoils with chord is given by the following expression:
Remember that these forces calculated are normal and tangential to the apparent speed. We are interested in forces in the and axes. Thus we need to consider the diagram below:
Thus we can see the following:
is the force that is responsible for the rotation of the rotor blades; is the force that is responsible for the bending of the blades.
Recall that for an isolated system the net angular momentum of the system is conserved. If the rotor acquired angular momentum, so must the fluid in the wake. Let us suppose that the fluid in the wake acquires a tangential velocity . Thus the torque in the air is given by
By the conservation of angular momentum, this balances the torque in the blades of the rotor; thus,
Furthermore, the rate of change of linear momentum in the air is balanced by the out-of-plane bending force acting on the blades, . From momentum theory, the rate of change of linear momentum in the air is as follows:
which may be expressed as
Balancing this with the out-of-plane bending force gives
Let us now make the following definitions:
So we have the following equations:
Let us make reference to the following equation which can be seen from analysis of the above figure:
Thus, with these three equations, it is possible to get the following result through some algebraic manipulation:
We can derive an expression for in a similar manner. This allows us to understand what is going on with the rotor and the fluid. Equations of this sort are then solved by iterative techniques. | 1 | Applied and Interdisciplinary Chemistry |
Formate dehydrogenases are a set of enzymes that catalyse the oxidation of formate to carbon dioxide, donating the electrons to a second substrate, such as NAD in formate:NAD+ oxidoreductase () or to a cytochrome in formate:ferricytochrome-b1 oxidoreductase (). This family of enzymes has attracted attention as inspiration or guidance on methods for the carbon dioxide fixation, relevant to global warming. | 1 | Applied and Interdisciplinary Chemistry |
Trioxidane can be obtained in small, but detectable, amounts in reactions of ozone and hydrogen peroxide, or by the electrolysis of water. Larger quantities have been prepared by the reaction of ozone with organic reducing agents at low temperatures in a variety of organic solvents, such as the anthraquinone process. It is also formed during the decomposition of organic hydrotrioxides (ROOOH). Alternatively, trioxidane can be prepared by reduction of ozone with 1,2-diphenylhydrazine at low temperature. Using a resin-bound version of the latter, relatively pure trioxidane can be isolated as a solution in organic solvent. Preparation of high purity solutions is possible using the methyltrioxorhenium(VII) catalyst. In acetone-d at −20 °C, the characteristic H NMR signal of trioxidane could be observed at a chemical shift of 13.1 ppm. Solutions of hydrogen trioxide in diethyl ether can be safely stored at −20 °C for as long as a week.
The reaction of ozone with hydrogen peroxide is known as the "peroxone process". This mixture has been used for some time for treating groundwater contaminated with organic compounds. The reaction produces HO and HO. | 0 | Theoretical and Fundamental Chemistry |
Torovirus is a genus of viruses within the family Coronaviridae, subfamily Torovirinae that primarily infect vertebrates and include Berne virus of horses and Breda virus of cattle. They cause gastroenteritis in mammals, including humans but rarely. | 1 | Applied and Interdisciplinary Chemistry |
Cheon Jinwoo is the H.G. Underwood Professor at Yonsei University and the Director of the Center for Nanomedicine, Institute for Basic Science (IBS). As a leading chemist in inorganic materials chemistry and nanomedicine Cheon and his group research chemical principles for the preparation of complex inorganic materials. He has been a Clarivate Analytics Highly Cited Researcher both in the field of chemistry in 2014, 2015, 2016 and cross-field in 2018. He is a fellow of the American Chemical Society, Royal Society of Chemistry, and Korean Academy of Science and Technology, a senior editor of Accounts of Chemical Research and an editorial advisory board member of Journal of Materials Chemistry, Nano Letters and Materials Horizons. | 0 | Theoretical and Fundamental Chemistry |
* Nobel Prizes in Chemistry (2012), The Nobel Prize in Chemistry 2009, Venkatraman Ramakrishnan, Thomas A. Steitz, Ada E. Yonath, [http://www.nobelprize.org/nobel_prizes/chemistry/laureates/2009/illpres.html The Nobel Prize in Chemistry 2009], accessed 13 June 2011.
* Nobel Prizes in Chemistry (2012), The Nobel Prize in Chemistry 1982, Aaron Klug, [http://www.nobelprize.org/nobel_prizes/chemistry/laureates/1982/press.html The Nobel Prize in Chemistry 1982], accessed 13 June 2011. | 1 | Applied and Interdisciplinary Chemistry |
UV can influence indoor air chemistry, leading to the formation of ozone and other potentially harmful pollutants, including particulate pollution. This occurs primarily through photolysis, where UV photons break molecules into smaller radicals that form radicals such as OH. The radicals can react with volatile organic compounds (VOCs) to produce oxidized VOCs (OVOCs) and secondary organic aerosols (SOA).
Wavelengths below 242 nm can also generate ozone, which not only contributes to OVOCs and SOA formation but can be harmful in itself. When inhaled in high quantities, these pollutants can irritate the eyes and respiratory system and exacerbate conditions like asthma.
The specific pollutants produced depend on the initial air chemistry and the UV source power and wavelength. To control ozone and other indoor pollutants, ventilation and filtration methods are used, diluting airborne pollutants and maintaining indoor air quality. | 0 | Theoretical and Fundamental Chemistry |
Genome-wide CRISPR-Cas9 knockout screens aim to elucidate the relationship between genotype and phenotype by ablating gene expression on a genome-wide scale and studying the resulting phenotypic alterations. The approach utilises the CRISPR-Cas9 gene editing system, coupled with libraries of single guide RNAs (sgRNAs), which are designed to target every gene in the genome. Over recent years, the genome-wide CRISPR screen has emerged as a powerful tool for performing large-scale loss-of-function screens, with low noise, high knockout efficiency and minimal off-target effects. | 1 | Applied and Interdisciplinary Chemistry |
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