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The procedure begins by making a cell lysate of the cells of interest. This lysate contains polysomes, monosomes (composed of one ribosome residing on an mRNA), the small (40S in eukaryotes) and large (60S in eukaryotes) ribosomal subunits, "free" mRNA and a host of other soluble cellular components.
The procedure continues by making a continuous sucrose gradient of continuously variable density in a centrifuge tube. At the concentrations used (15-45% in the example), sucrose does not disrupt the association of ribosomes and mRNA. The 15% portion of the gradient is at the top of the tube, while the 45% portion is at the bottom because of their different density.
A specific amount (as measured by optical density) of the lysate is then layered gently on top of the gradient in the tube. The lysate, even though it contains a large amount of soluble material, is much less dense than 15% sucrose, and so it can be kept as a separate layer at the top of the tube if this is done gently.
In order to separate the components of the lysate, the preparation is subjected to centrifugation. This accelerates the components of the lysate with many times the force of gravity and thus propels them through the gradient based upon how "big" the individual components are. The small (40S) subunits travel less far into the gradient than the large (60S) subunits. The 80S ribosomes on an mRNA travel further (note that the contribution of the size of the mRNA to the distance traveled is not significant). Polysomes composed of 2 ribosomes travel further, polysomes with 3 ribosomes travel further still, and on and on. The "size" of the components is designated by S, the svedberg unit. Note that one S = 10 seconds, and that the concept of "big" is actually an oversimplification.
After centrifugation, the contents of the tube are collected as fractions from the top (smaller, slower traveling) to bottom (bigger, faster traveling) and the optical density of the fractions is determined. The first fractions removed have a large amount of relatively small molecules, such as tRNAs, individual proteins, etc. | 1 | Applied and Interdisciplinary Chemistry |
Phred was originally conceived in the early 1990s by Phil Green, then a professor at Washington University in St. Louis. LaDeana Hillier, Michael Wendl, David Ficenec, Tim Gleeson, Alan Blanchard, and Richard Mott also contributed to the codebase and algorithm. Green moved to University of Washington in the mid 1990s, after which development was primarily managed by himself and Brent Ewing. Phred played a notable role in the Human Genome Project, where large amounts of sequence data were processed by automated scripts. It was at the time the most widely used base-calling software program by both academic and commercial DNA sequencing laboratories because of its high base calling accuracy. Phred is distributed commercially by [http://www.codoncode.com CodonCode Corporation], and used to perform the "Call bases" function in the program CodonCode Aligner. It is also used by the MacVector plugin Assembler. | 1 | Applied and Interdisciplinary Chemistry |
* [https://www.wikidata.org/wiki/Q101294270 Васина Т. А.] Формирование горнозаводских округов в конце XVIII — первой половине XIX веков на территории современной Удмуртии // Научный диалог — 2019. — вып. 7. — С. 222—239. — ISSN 2227-1295 — [https://www.nauka-dialog.ru/jour/article/view/1254 doi:10.24224/2227-1295-2019-7-222-239]
* Запарий В. В. [https://cyberleninka.ru/article/n/predystoriya-sozdaniya-metallurgii-na-urale|Предыстория создания металлургии на Урале] // Историко-экономические исследования : журнал. — Иркутск: Федеральное государственное бюджетное образовательное учреждение высшего образования «Байкальский государственный университет», 2015. — Т. 16, № 2. — С. 349—365. — ISSN 2308-2488. — doi:10.17150/2308-2588.2015.16(2).349-365.
* Запарий В. В. [https://cyberleninka.ru/article/n/metallurgiya-urala-v-epohu-potryaseniy-pervaya-mirovaya-i-grazhdanskaya-voyny Металлургия Урала в эпоху потрясений Первая мировая и Гражданская войны] // Историко-экономические исследования : журнал. — Иркутск: Федеральное государственное бюджетное образовательное учреждение высшего образования «Байкальский государственный университет», 2015. — Т. 16, № 1. — С. 67—108. — ISSN 2308-2488. — doi:10.17150/2308-2588.2015.16(1).67-108.
* Запарий В. В. [https://cyberleninka.ru/article/n/petrovskaya-modernizatsiya-i-metallurgiya-urala-1700-1725 Петровская модернизация и металлургия Урала (1700–1725)] // Историко-экономические исследования : журнал. — Иркутск: Федеральное государственное бюджетное образовательное учреждение высшего образования «Байкальский государственный университет», 2016. — Т. 17, № 1. — С. 95—140. — ISSN 2308-2488. — doi:10.17150/2308-2588.2016.17(1).95-140.
* Мударисов Р. З. [https://elar.urfu.ru/handle/10995/64248 К вопросу о кризисе горнозаводской промышленности Южного Урала в первой половине XIX века] // Урал индустриальный. Бакунинские чтения. Индустриальная модернизация России в XVIII–XXI вв.: материалы XIII Всероссийской научной конференции, Екатеринбург, 18—19 октября 2018 г.: в 2-х томах. — Екатеринбург: УрО РАН, 2018. — Т. 1. — С. 63—72. — ISBN 978-5-7691-2504-1.
* Пыхалов И. В. [https://cyberleninka.ru/article/n/razvitie-chyornoy-metallurgii-v-rossiyskoy-imperii Развитие чёрной металлургии в Российской империи] // Проблемы современной экономики : журнал. — СПб.: ООО «Научно-производственная компания «РОСТ», 2017. — № 1 (61). — С. 95—140. — ISSN 1818-3395. | 1 | Applied and Interdisciplinary Chemistry |
Soil acidification is the buildup of hydrogen cations, which reduces the soil pH. Chemically, this happens when a proton donor gets added to the soil. The donor can be an acid, such as nitric acid, sulfuric acid, or carbonic acid. It can also be a compound such as aluminium sulfate, which reacts in the soil to release protons. Acidification also occurs when base cations such as calcium, magnesium, potassium and sodium are leached from the soil.
Soil acidification naturally occurs as lichens and algae begin to break down rock surfaces. Acids continue with this dissolution as soil develops. With time and weathering, soils become more acidic in natural ecosystems. Soil acidification rates can vary, and increase with certain factors such as acid rain, agriculture, and pollution. | 0 | Theoretical and Fundamental Chemistry |
The earliest sewers were designed to carry street runoff away from inhabited areas and into surface waterways without treatment. Before the 19th century, it was commonplace to empty human waste receptacles, e.g., chamber pots, into town and city streets and slaughter animals in open street "shambles". The use of draft animals such as horses and herding of livestock through city streets meant that most contained large amounts of excrement. Before the development of macadam as a paving material in the 19th century, paving systems were mostly porous, so that precipitation could soak away and not run off, and urban rooftop rainwater was often saved in rainwater tanks. Open sewers, consisting of gutters and urban streambeds, were common worldwide before the 20th century.
In the majority of developed countries, large efforts were made during the late 19th and early 20th centuries to cover the formerly open sewers, converting them to closed systems with cast iron, steel, or concrete pipes, masonry, and concrete arches, while streets and footpaths were increasingly covered with impermeable paving systems. Most sewage collection systems of the 19th and early to mid-20th century used single-pipe systems that collect both sewage and urban runoff from streets and roofs (to the extent that relatively clean rooftop rainwater was not saved in butts and cisterns for drinking and washing.) This type of collection system is referred to as a "combined sewer system". The rationale for combining the two was that it would be cheaper to build just a single system. Most cities at that time did not have sewage treatment plants, so there was no perceived public health advantage in constructing a separate "surface water sewerage" (UK terminology) or "storm sewer" (US terminology) system. Moreover, before the automobile era, runoff was likely to be typically highly contaminated with animal waste. Further, until the mid-late 19th century the frequent use of shambles contributed more waste. The widespread replacement of horses with automotive propulsion, paving of city streets and surfaces, construction of municipal slaughterhouses, and provision of mains water in the 20th century changed the nature and volume of urban runoff to be initially cleaner, include water that formerly soaked away and previously saved rooftop rainwater after combined sewers were already widely adopted.
When constructed, combined sewer systems were typically sized to carry three to 160 times the average dry weather sewage flows. It is generally infeasible to treat the volume of mixed sewage and surface runoff flowing in a combined sewer during peak runoff events caused by snowmelt or convective precipitation. As cities built sewage treatment plants, those plants were typically built to treat only the volume of sewage flowing during dry weather. Relief structures were installed in the collection system to bypass untreated sewage mixed with surface runoff during wet weather, protecting sewage treatment plants from damage caused if peak flows reached the headworks. | 1 | Applied and Interdisciplinary Chemistry |
As hormones are defined functionally, not structurally, they may have diverse chemical structures. Hormones occur in multicellular organisms (plants, animals, fungi, brown algae, and red algae). These compounds occur also in unicellular organisms, and may act as signaling molecules however there is no agreement that these molecules can be called hormones. | 1 | Applied and Interdisciplinary Chemistry |
The equations solved in this approach arise from the implicit time integration of the incompressible Navier–Stokes equations.
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is computed by first calculating a residual value , resulting from spurious mass flux, then using this mass imbalance to get a new pressure value. The pressure value that is attempted to compute, is such that when plugged into momentum equations a divergence-free velocity field results. The mass imbalance is often also used for control of the outer loop.<br>
The name of this class of methods stems from the fact that the correction of the velocity field is computed through the pressure-field.
The discretization of this is typically done with either the finite element method or the finite volume method. With the latter, one might also encounter the dual mesh, i.e. the computation grid obtained from connecting the centers of the cells that the initial subdivision into finite elements of the computation domain yielded. | 1 | Applied and Interdisciplinary Chemistry |
Radical disproportionation is often thought of as occurring in a linear fashion with the donor radical, the acceptor radical, and the atom being accepted all along the same axis. In fact, most disproportionation reactions do not require linear orientations in space. Molecules that are more sterically hindered require arrangements that are more linear, and thus react more slowly. Steric effects play a significant role in disproportionation with ethyl radicals acting as more effective acceptors than tert-butyl radicals. Tert-butyl radicals have many hydrogens on adjacent carbons to donate and steric effects often prevent tert-butyl radicals from getting close to abstracting hydrogens. | 0 | Theoretical and Fundamental Chemistry |
These compounds are bound together by metal-metal bonding as well as two kinds of ligands. Ligands that span the faces or edges of the M core are labeled L, for inner (innen in the original German description), and those ligands attached only to one metal are labeled outer, or L for ausser. Typically, the outer ligands can be exchanged whereas the bridging ligands are more inert toward substitution. | 0 | Theoretical and Fundamental Chemistry |
Its name is derived from the word “pigment” (P) and the presence of a major bleaching band centered around 680-685 nm in the flash-induced absorbance difference spectra of P680/ P680+•. | 0 | Theoretical and Fundamental Chemistry |
Laser snow is the precipitation through a chemical reaction, condensation and coagulation process, of clustered atoms or molecules, induced by passing a laser beam through certain gasses. It was first observed by Tam, Moe and Happer in 1975, and has since been noted in a number of gases. | 0 | Theoretical and Fundamental Chemistry |
It is known that muscarinic acetylcholine receptors also appear on the pre-synaptic membrane of somatic neurons in the neuro-muscular junction, where they are involved in the regulation of acetylcholine release. | 1 | Applied and Interdisciplinary Chemistry |
Cosmogenic nuclides (or cosmogenic isotopes) are rare nuclides (isotopes) created when a high-energy cosmic ray interacts with the nucleus of an in situ Solar System atom, causing nucleons (protons and neutrons) to be expelled from the atom (see cosmic ray spallation). These nuclides are produced within Earth materials such as rocks or soil, in Earth's atmosphere, and in extraterrestrial items such as meteoroids. By measuring cosmogenic nuclides, scientists are able to gain insight into a range of geological and astronomical processes. There are both radioactive and stable cosmogenic nuclides. Some of these radionuclides are tritium, carbon-14 and phosphorus-32.
Certain light (low atomic number) primordial nuclides (isotopes of lithium, beryllium and boron) are thought to have been created not only during the Big Bang, but also (and perhaps primarily) to have been made after the Big Bang, but before the condensation of the Solar System, by the process of cosmic ray spallation on interstellar gas and dust. This explains their higher abundance in cosmic dust as compared with their abundances on Earth. This also explains the overabundance of the early transition metals just before iron in the periodic table – the cosmic-ray spallation of iron produces scandium through chromium on the one hand and helium through boron on the other. However, the arbitrary defining qualification for cosmogenic nuclides of being formed "in situ in the Solar System" (meaning inside an already-aggregated piece of the Solar System) prevents primordial nuclides formed by cosmic ray spallation before the formation of the Solar System from being termed "cosmogenic nuclides"—even though the mechanism for their formation is exactly the same. These same nuclides still arrive on Earth in small amounts in cosmic rays, and are formed in meteoroids, in the atmosphere, on Earth, "cosmogenically". However, beryllium (all of it stable beryllium-9) is present primordially in the Solar System in much larger amounts, having existed prior to the condensation of the Solar System, and thus present in the materials from which the Solar System formed.
To make the distinction in another fashion, the timing of their formation determines which subset of cosmic ray spallation-produced nuclides are termed primordial or cosmogenic (a nuclide cannot belong to both classes). By convention, certain stable nuclides of lithium, beryllium, and boron are thought to have been produced by cosmic ray spallation in the period of time between the Big Bang and the Solar System's formation (thus making these primordial nuclides, by definition) are not termed "cosmogenic", even though they were formed by the same process as the cosmogenic nuclides (although at an earlier time). The primordial nuclide beryllium-9, the only stable beryllium isotope, is an example of this type of nuclide.
In contrast, even though the radioactive isotopes beryllium-7 and beryllium-10 fall into this series of three light elements (lithium, beryllium, boron) formed mostly by cosmic ray spallation nucleosynthesis, both of these nuclides have half lives too short (53 days and ca. 1.4 million years, resp.) for them to have been formed before the formation of the Solar System, and thus they cannot be primordial nuclides. Since the cosmic ray spallation route is the only possible source of beryllium-7 and beryllium-10 occurrence naturally in the environment, they are therefore cosmogenic. | 0 | Theoretical and Fundamental Chemistry |
Micelles form only when the concentration of surfactant is greater than the critical micelle concentration (CMC), and the temperature of the system is greater than the critical micelle temperature, or Krafft temperature. The formation of micelles can be understood using thermodynamics: Micelles can form spontaneously because of a balance between entropy and enthalpy. In water, the hydrophobic effect is the driving force for micelle formation, despite the fact that assembling surfactant molecules is unfavorable in terms of both enthalpy and entropy of the system. At very low concentrations of the surfactant, only monomers are present in solution. As the concentration of the surfactant is increased, a point is reached at which the unfavorable entropy contribution, from clustering the hydrophobic tails of the molecules, is overcome by a gain in entropy due to release of the solvation shells around the surfactant tails. At this point, the lipid tails of a part of the surfactants must be segregated from the water. Hence, they start to form micelles. In broad terms, above the CMC, the loss of entropy due to assembly of the surfactant molecules is less than the gain in entropy by setting free the water molecules that were "trapped" in the solvation shells of the surfactant monomers. Also important are enthalpic considerations, such as the electrostatic interactions that occur between the charged parts of surfactants. | 0 | Theoretical and Fundamental Chemistry |
For a long time, it was normal procedure for a decommissioned blast furnace to be demolished and either be replaced with a newer, improved one, or to have the entire site demolished to make room for follow-up use of the area. In recent decades, several countries have realized the value of blast furnaces as a part of their industrial history. Rather than being demolished, abandoned steel mills were turned into museums or integrated into multi-purpose parks. The largest number of preserved historic blast furnaces exists in Germany; other such sites exist in Spain, France, the Czech Republic, Great Britain. Japan, Luxembourg, Poland, Romania, Mexico, Russia and the United States. | 1 | Applied and Interdisciplinary Chemistry |
The ability to produce chemical state information, i.e. the local bonding environment of an atomic species in question from the topmost few nanometers of the sample makes XPS a unique and valuable tool for understanding the chemistry of the surface. The local bonding environment is affected by the formal oxidation state, the identity of its nearest-neighbor atoms, and its bonding hybridization to the nearest-neighbor or next-nearest-neighbor atoms. For example, while the nominal binding energy of the C electron is 284.6 eV, subtle but reproducible shifts in the actual binding energy, the so-called chemical shift (analogous to NMR spectroscopy), provide the chemical state information.
Chemical-state analysis is widely used for carbon. It reveals the presence or absence of the chemical states of carbon, in approximate order of increasing binding energy, as: carbide (-C), silane (-Si-CH), methylene/methyl/hydrocarbon (-CH-CH-, CH-CH-, and -CH=CH-), amine (-CH-NH), alcohol (-C-OH), ketone (-C=O), organic ester (-COOR), carbonate (-CO), monofluoro-hydrocarbon (-CFH-CH-), difluoro-hydrocarbon (-CF-CH-), and trifluorocarbon (-CH-CF), to name but a few.
Chemical state analysis of the surface of a silicon wafer reveals chemical shifts due to different formal oxidation states, such as: n-doped silicon and p-doped silicon (metallic silicon), silicon suboxide (SiO), silicon monoxide (SiO), SiO, and silicon dioxide (SiO). An example of this is seen in the figure "High-resolution spectrum of an oxidized silicon wafer in the energy range of the Si 2p signal". | 0 | Theoretical and Fundamental Chemistry |
A free concentration [A] or activity {A} of a species A is measured by means of an ion selective electrode such as the glass electrode. If the electrode is calibrated using activity standards it is assumed that the Nernst equation applies in the form
where is the standard electrode potential. When buffer solutions of known pH are used for calibration the meter reading will be a pH.
At 298 K, 1 pH unit is approximately equal to 59 mV.
When the electrode is calibrated with solutions of known concentration, by means of a strong acid–strong base titration, for example, a modified Nernst equation is assumed.
where is an empirical slope factor. A solution of known hydrogen ion concentration may be prepared by standardization of a strong acid against borax. Constant-boiling hydrochloric acid may also be used as a primary standard for hydrogen ion concentration. | 0 | Theoretical and Fundamental Chemistry |
It is used in organic synthesis. One example is in the Perkin synthesis: the formation of unsaturated cinnamic-type acids by the condensation of aromatic aldehydes with fatty acids. Replacement of the commonly used sodium acetate with caesium acetate has been shown to improve yields by up to 10 times.
It is often used to invert secondary alcohols, first by direct S2 substitution of the hydroxyl group with acetate, which is then converted back to a hydroxyl group.
Caesium acetate is occasionally used instead of caesium formate in petroleum drilling fluids. | 0 | Theoretical and Fundamental Chemistry |
The endocannabinoid system is by molecular phylogenetic distribution of apparently ancient lipids in the plant kingdom, indicative of biosynthetic plasticity and potential physiological roles of endocannabinoid-like lipids in plants, and detection of arachidonic acid (AA) indicates chemotaxonomic connections between monophyletic groups with common ancestor dates to around 500 million years ago (Cambrian). The phylogenetic distribution of these lipids may be a consequence of interactions/adaptations to the surrounding conditions such as chemical plant-pollinator interactions, communication and defense mechanisms. The two novel EC-like molecules derived from the eicosatetraenoic acid juniperonic acid, an omega-3 structural isomer of AA, namely juniperoyl ethanolamide and 2-juniperoyl glycerol (1/2-AG) in gymnosperms, lycophytes and few monilophytes, show AA is an evolutionarily conserved signalling molecule that acts in plants in response to stress similar to that in animal systems. The endocannabinoid Docosatetraenoylethanolamide has been found in Tropaeolum tuberosum (Mashua) and Leonotis leonurus (Lion's tail) Maca contains several N-benzylamides referred to as "macamides" that are structurally related to endocannabinoids such as the N-Benzyl analog of Oleamide. Echinacea contains alkylamides structurally related to endocannabinoids. | 1 | Applied and Interdisciplinary Chemistry |
In fluid dynamics, a barotropic fluid is a fluid whose density is a function of pressure only. The barotropic fluid is a useful model of fluid behavior in a wide variety of scientific fields, from meteorology to astrophysics.
The density of most liquids is nearly constant (isopycnic), so it can be stated that their densities vary only weakly with pressure and temperature. Water, which varies only a few percent with temperature and salinity, may be approximated as barotropic. In general, air is not barotropic, as it is a function of temperature and pressure; but, under certain circumstances, the barotropic assumption can be useful.
In astrophysics, barotropic fluids are important in the study of stellar interiors or of the interstellar medium. One common class of barotropic model used in astrophysics is a polytropic fluid. Typically, the barotropic assumption is not very realistic.
In meteorology, a barotropic atmosphere is one that for which the density of the air depends only on pressure, as a result isobaric surfaces (constant-pressure surfaces) are also constant-density surfaces. Such isobaric surfaces will also be isothermal surfaces, hence (from the thermal wind equation) the geostrophic wind will not vary with depth. Hence, the motions of a rotating barotropic air mass is strongly constrained. The tropics are more nearly barotropic than mid-latitudes because temperature is more nearly horizontally uniform in the tropics.
A barotropic flow is a generalization of a barotropic atmosphere. It is a flow in which the pressure is a function of the density only and vice versa. In other words, it is a flow in which isobaric surfaces are isopycnic surfaces and vice versa. One may have a barotropic flow of a non-barotropic fluid, but a barotropic fluid will always follow a barotropic flow. Examples include barotropic layers of the oceans, an isothermal ideal gas or an isentropic ideal gas.
A fluid which is not barotropic is baroclinic, i. e., pressure is not the only factor to determine density. For a barotropic fluid or a barotropic flow (such as a barotropic atmosphere), the baroclinic vector is zero. | 1 | Applied and Interdisciplinary Chemistry |
High-angle grain boundaries, which have large misorientations between adjacent grains, tend to have higher interfacial energy and are more effective in impeding dislocation motion. In contrast, low-angle grain boundaries with small misorientations and lower interfacial energy may allow for easier dislocation transmission and exhibit weaker grain boundary strengthening effects. | 1 | Applied and Interdisciplinary Chemistry |
Symptoms following bee sting may include:
*Local effects: burning or stinging pain, swelling, redness.
*Severe systemic reactions: swelling of the tongue and throat, difficulty breathing, and shock.
*Development of optic neuritis and atrophy.
*Atrial fibrillation, cerebral infarction, acute myocardial infarction, Fisher's syndrome, acute inflammatory polyradiculopathy (Guillain–Barré syndrome), claw hand (through a central action of apamin on the spinal cord and a peripheral action in the form of median and ulnar neuritis, causing spasms of the long flexors in the forearm).
Patients poisoned with bee venom can be treated with anti-inflammatory medication, antihistamines and oral prednisolone.
Apamin is an element in bee venom. You can come into contact with apamin through bee venom, so the symptoms that are known are not caused by apamin directly, but by the venom as a whole. Apamin is the only neurotoxin acting purely on the central nervous system. The symptoms of apamin toxicity are not well known, because people are not easily exposed to the toxin alone.
Through research about the neurotoxicity of apamin some symptoms were discovered. In mice, the injection of apamin produces convulsions and long-lasting spinal spasticity. Also, it is known that the polysynaptic spinal reflexes are disinhibited in cats. Polysynaptic reflex is a reflex action that transfers an impulse from a sensory neuron to a motor neuron via an interneuron in the spinal cord. In rats, apamin was found to cause tremor and ataxia, as well as dramatic haemorrhagic effects in the lungs.
Furthermore, apamin has been found to be 1000 times more efficient when applied into the ventricular system instead of the peripheral nervous system. The ventricular system is a set of structures in the brain containing cerebrospinal fluid. The peripheral nervous system contains the nerves and ganglia outside of the brain and spinal cord. This difference in efficiency can easily be explained. Apamin binds to the SK channels, which differ slightly in different tissues. So apamin binding is probably stronger in SK channels in the ventricular system than in other tissues. | 1 | Applied and Interdisciplinary Chemistry |
By using the Lorentz Reciprocal Theorem, one finds the velocity vector of the particle . The flow in a fixed lab frame is given by :
<br />
with swimming speed . Note, that and . | 1 | Applied and Interdisciplinary Chemistry |
Eukaryotic transcription repressors share some of the mechanisms used by their prokaryotic counterparts. For example, by binding to a site on DNA that overlaps with the binding site of an activator, a repressor can inhibit binding of the activator. But more frequently, eukaryotic repressors inhibit the function of an activator by masking its activating domain, preventing its nuclear localization, promoting its degradation, or inactivating it through chemical modifications. Repressors can directly inhibit transcription initiation by binding to a site upstream of a promoter and interacting with the transcriptional machinery. Repressors can indirectly repress transcription by recruiting histone modifiers (deacetylases and methylases) or nucleosome remodeling enzymes that affect the accessibility of the DNA. Repressing histone and DNA modifications are also the basis of transcriptional silencing that can spread along the chromatin and switch off multiple genes. | 1 | Applied and Interdisciplinary Chemistry |
Tin extraction and use can be dated to the beginning of the Bronze Age around 3000 BC, during which copper objects formed from polymetallic ores had different physical properties. The earliest bronze objects had tin or arsenic content of less than 2% and are therefore believed to be the result of unintentional alloying due to trace metal content in copper ores such as tennantite, which contains arsenic. The addition of a second metal to copper increases its hardness, lowers the melting temperature, and improves the casting process by producing a more fluid melt that cools to a denser, less spongy metal. This was an important innovation that allowed for the much more complex shapes cast in closed molds of the Bronze Age. Arsenical bronze objects appear first in the Middle East where arsenic is commonly found in association with copper ore, but the health risks were quickly realized and the quest for sources of the much less hazardous tin ores began early in the Bronze Age. This created the demand for rare tin metal and formed a trade network that linked the distant sources of tin to the markets of Bronze Age cultures.
Cassiterite (SnO), oxidized tin, most likely was the original source of tin in ancient times. Other forms of tin ores are less abundant sulfides such as stannite that require a more involved smelting process. Cassiterite often accumulates in alluvial channels as placer deposits due to the fact that it is harder, heavier, and more chemically resistant than the granite in which it typically forms. These deposits can be easily seen in river banks, because cassiterite is usually black or purple or otherwise dark, a feature exploited by early Bronze Age prospectors. It is likely that the earliest deposits were alluvial and perhaps exploited by the same methods used for panning gold in placer deposits. | 1 | Applied and Interdisciplinary Chemistry |
* c. 520 BC – Alcmaeon of Croton distinguished veins from arteries and discovered the optic nerve.
* c. 450 BC – Sushruta wrote the Sushruta Samhita, redacted versions of which, by the third century AD, describe over 120 surgical instruments and 300 surgical procedures, classify human surgery into eight categories, and introduce cosmetic surgery.
* c. 450 BC – Xenophanes examined fossils and speculated on the evolution of life.
* c. 380 BC – Diocles wrote the oldest known anatomy book and was the first to use the term anatomy.
* c. 350 BC – Aristotle attempted a comprehensive classification of animals. His written works include Historion Animalium, a general biology of animals, De Partibus Animalium, a comparative anatomy and physiology of animals, and De Generatione Animalium, on developmental biology.
* c. 300 BC – Theophrastos (or Theophrastus) began the systematic study of botany.
* c. 300 BC – Herophilos dissected the human body.
* c. 50–70 AD – Historia Naturalis by Pliny the Elder (Gaius Plinius Secundus) was published in 37 volumes.
* 130–200 – Claudius Galen wrote numerous treatises on human anatomy.
* c. 1010 – Avicenna (Abu Ali al Hussein ibn Abdallah ibn Sina) published The Canon of Medicine.
* 1543 – Andreas Vesalius publishes the anatomy treatise De humani corporis fabrica. | 1 | Applied and Interdisciplinary Chemistry |
Two methods are used to assign raw sequence reads to genomic features (i.e., assemble the transcriptome):
* De novo: This approach does not require a reference genome to reconstruct the transcriptome, and is typically used if the genome is unknown, incomplete, or substantially altered compared to the reference. Challenges when using short reads for de novo assembly include 1) determining which reads should be joined together into contiguous sequences (contigs), 2) robustness to sequencing errors and other artifacts, and 3) computational efficiency. The primary algorithm used for de novo assembly transitioned from overlap graphs, which identify all pair-wise overlaps between reads, to de Bruijn graphs, which break reads into sequences of length k and collapse all k-mers into a hash table. Overlap graphs were used with Sanger sequencing, but do not scale well to the millions of reads generated with RNA-Seq. Examples of assemblers that use de Bruijn graphs are Trinity, Oases (derived from the genome assembler Velvet), Bridger, and rnaSPAdes. Paired-end and long-read sequencing of the same sample can mitigate the deficits in short read sequencing by serving as a template or skeleton. Metrics to assess the quality of a de novo assembly include median contig length, number of contigs and N50.
* Genome guided: This approach relies on the same methods used for DNA alignment, with the additional complexity of aligning reads that cover non-continuous portions of the reference genome. These non-continuous reads are the result of sequencing spliced transcripts (see figure). Typically, alignment algorithms have two steps: 1) align short portions of the read (i.e., seed the genome), and 2) use dynamic programming to find an optimal alignment, sometimes in combination with known annotations. Software tools that use genome-guided alignment include Bowtie, TopHat (which builds on BowTie results to align splice junctions), Subread, STAR, HISAT2, and GMAP. The output of genome guided alignment (mapping) tools can be further used by tools such as Cufflinks or StringTie to reconstruct contiguous transcript sequences (i.e., a FASTA file). The quality of a genome guided assembly can be measured with both 1) de novo assembly metrics (e.g., N50) and 2) comparisons to known transcript, splice junction, genome, and protein sequences using precision, recall, or their combination (e.g., F1 score). In addition, in silico assessment could be performed using simulated reads.
A note on assembly quality: The current consensus is that 1) assembly quality can vary depending on which metric is used, 2) assembly tools that scored well in one species do not necessarily perform well in the other species, and 3) combining different approaches might be the most reliable. | 1 | Applied and Interdisciplinary Chemistry |
Ekman suction is the component of Ekman transport that results in areas of upwelling due to the divergence of water. Returning to the concept of mass conservation, any water displaced by Ekman transport must be replenished. As the water diverges it creates space and acts as a suction in order to fill in the space by pulling up, or upwelling, deep sea water to the euphotic zone.
Ekman suction has major consequences for the biogeochemical processes in the area because it leads to upwelling. Upwelling carries nutrient rich, and cold deep-sea water to the euphotic zone, promoting phytoplankton blooms and kickstarting an extremely high-productive environment. Areas of upwelling lead to the promotion of fisheries, in fact nearly half of the world's fish catch comes from areas of upwelling.
Ekman suction occurs both along coastlines and in the open ocean, but also occurs along the equator. Along the Pacific coastline of California, Central America, and Peru, as well as along the Atlantic coastline of Africa there are areas of upwelling due to Ekman suction, as the currents move equatorwards. Due to the Coriolis effect the surface water moves 90° to the left (in the South Hemisphere, as it travels toward the equator) of the wind current, therefore causing the water to diverge from the coast boundary, leading to Ekman suction. Additionally, there are areas of upwelling as a consequence of Ekman suction where the Polar Easterlies winds meet the Westerlies in the subpolar regions north of the subtropics, as well as where the Northeast Trade Winds meet the Southeast Trade Winds along the Equator. Similarly, due to the Coriolis effect the surface water moves 90° to the left (in the South Hemisphere) of the wind currents, and the surface water diverges along these boundaries, resulting in upwelling in order to conserve mass. | 1 | Applied and Interdisciplinary Chemistry |
Emerin is a serine-rich nuclear membrane protein and a member of the nuclear lamina-associated protein family. It mediates membrane anchorage to the cytoskeleton. Emery–Dreifuss muscular dystrophy is an X-linked inherited degenerative myopathy resulting from mutation in the EMD (also known clinically as STA) gene. Emerin appears to be involved in mechanotransduction, as emerin-deficient mouse fibroblasts failed to transduce normal mechanosensitive gene expression responses to strain stimuli. In cardiac muscle, emerin is also found complexed to beta-catenin at adherens junctions of intercalated discs, and cardiomyocytes from hearts lacking emerin showed beta-catenin redistribution as well as perturbed intercalated disc architecture and myocyte shape. This interaction appears to be regulated by glycogen synthase kinase 3 beta. | 1 | Applied and Interdisciplinary Chemistry |
Feedlots play an integral role in the Australian livestock industry and are strongly influenced by the environment they are in. Only 25% of Australia (including its feedlots) have a growing season of more than 5 months. This is due to the Australian climate being incapable of sustaining crops and pastures over a sustained period of time. Characteristically, cattle and grain supplies are located in close proximity to feedlots, and the 2012 Australian Lot feeders Association Industry survey indicated that feedlot capacity is typically divided into particular sectors.
Whilst the southern states account for 51% of total feedlot capacity in Australia, NSW only possesses 45% of total feedlots. The effect of this feedlot distribution is that the southern states produce 1 266 710 heads of cows whilst NSW only owns 788 625 heads of cattle. These figures demonstrate how environmental and infrastructural conditions must be accounted for throughout Australian pastoral systems, thereby indicating how these influences have had an effect on the Southern and Northern rangeland industry. Further, in the Southern rangelands where there is a growing season of less than 5 months, sheep stations have been implemented to complement the farming of cattle. In comparison, the Northern beef zone takes up 116 million hectares of Australia's total land mass, which equates to 24.3% of the total land mass available; this figure is markedly different form the 265 million hectares consumed by the Southern rangelands (sheep and beef) which amounts to 55.3% of total land mass. The Northern rangelands are operated by multiple companies which occupy more than one station. | 1 | Applied and Interdisciplinary Chemistry |
The photophysical properties of the FbFPs are determined by the chromophore itself and its chemical surrounding in the protein. The extinction coefficient (ε) is around 14.200 Mcm at 450 nm for all described FbFPs, which is slightly higher than that of free FMN (ε = 12.200 Mcm ). The Fluorescence-Quantum yield (Φ) varies significantly between different FbFPs and ranges from 0.2 (phiLOV2.1) to 0.44 (EcFbFP and iLOV). This represents an almost twofold increase compared to free FMN (Φ = 0.25).<br />
The difference to free FMN is even more significant in the case of the photostabaility, the proteins resistance to bleach out during prolonged and intense irradiation with blue light. Based on the bleaching-halftime (the times it takes to reduce the initial fluorescence intensity to 50% upon illumination) the genetically engineered variant phiLOV2.1 is approximately 40x as stable as free FMN. This stabilizing effect can be observed for almost all FbFPs, although it is usually in the range of 5x - 10x.<br />
The average fluorescence lifetime of FbFPs is in the range of 3.17 (Pp2FbFP) and 5.7 ns (e.g. EcFbFP). They are thereby much longer than the ones of GFP derivatives, which are usually between 1,5 and 3 ns.
FbFPs are therefore well suited as donor domains in Förster resonance energy transfer (FRET) systems in conjunction with GFP derivatives like YFP as acceptor domains. | 1 | Applied and Interdisciplinary Chemistry |
Application of electric pulses of sufficient strength to the cell causes an increase in the trans-membrane potential difference, which provokes the membrane destabilization. Cell membrane permeability is increased and otherwise nonpermeant molecules enter the cell.
Although the mechanisms of gene electrotransfer are not yet fully understood, it was shown that the introduction of DNA only occurs in the part of the membrane facing the cathode and that several steps are needed for successful transfection: electrophoretic migration of DNA towards the cell, DNA insertion into the membrane, translocation across the membrane, migration of DNA towards the nucleus, transfer of DNA across the nuclear envelope and finally gene expression. There are a number of factors that can influence the efficiency of gene electrotransfer, such as: temperature, parameters of electric pulses, DNA concentration, electroporation buffer used, cell size and the ability of cells to express transfected genes. In in vivo gene electrotransfer, DNA diffusion through extracellular matrix, properties of tissue and overall tissue conductivity are also crucial. | 1 | Applied and Interdisciplinary Chemistry |
* Reviews some of the history and the issues of the saprobic system.
* Contains a short introduction to the saprobity index, and compares Pantle & Buck's method to the more complicated Zelinka & Marvan method.
;German | 1 | Applied and Interdisciplinary Chemistry |
There are many different approaches to transfer thermal energy to electricity, and the technologies to do so have existed for several decades.
An established approach is by using a thermoelectric device, where a change in temperature across a semiconductor material creates a voltage through a phenomenon known as the Seebeck effect.
A related approach is the use of thermogalvanic cells, where a temperature difference gives rise to an electric current in an electrochemical cell.
The organic Rankine cycle, offered by companies such as Ormat, is a very known approach, whereby an organic substance is used as working medium instead of water. The benefit is that this process can reject heat at lower temperatures for the production of electricity than the regular water steam cycle. An example of use of the steam Rankine cycle is the Cyclone Waste Heat Engine. | 0 | Theoretical and Fundamental Chemistry |
Transition (neither fully laminar nor fully turbulent) flow occurs in the range of Reynolds numbers between 2300 and 4000. The value of the Darcy friction factor is subject to large uncertainties in this flow regime. | 1 | Applied and Interdisciplinary Chemistry |
Measurement of electrolytes is a commonly performed diagnostic procedure, performed via blood testing with ion-selective electrodes or urinalysis by medical technologists. The interpretation of these values is somewhat meaningless without analysis of the clinical history and is often impossible without parallel measurements of renal function. The electrolytes measured most often are sodium and potassium. Chloride levels are rarely measured except for arterial blood gas interpretations since they are inherently linked to sodium levels. One important test conducted on urine is the specific gravity test to determine the occurrence of an electrolyte imbalance. | 0 | Theoretical and Fundamental Chemistry |
Pharmacokinetic properties (see table 3) are important when new drugs are developed.
Patients seek rapid onset of action to relief the headache. Relatively short t, good bioavailability and lipophilicity are pharmacokinetic properties that have been associated with rapid onset of action. It has been speculated that good ability to cross the blood brain barrier and relatively long terminal elimination half-life may result in a lower incidence of headache recurrence. Sumatriptan and rizatriptan undergo first pass hepatic metabolism and result in lower bioavailability.
= Elimination half-life;
t = Time to reach peak plasma drug concentration;
Cl = Renal Clearance;
LogD = Measure of lipophilicity at pH 7.4. Increasing number indicate greater solubility;
V = Volume of distribution</small><br /> | 1 | Applied and Interdisciplinary Chemistry |
2015 revisions added oxidizing materials to the existing Flammables classification. The other major change allowed and encouraged labels to incorporate the GHS signal word, hazard pictograms, and hazard statements. This addition helped identify additional dangers when dealing with materials that fit into multiple categories, like hydrogen sulfide, which is both flammable and toxic. | 1 | Applied and Interdisciplinary Chemistry |
Because their double bonds are electron rich, enols behave as nucleophiles and react with electrophiles in much the same way that alkenes do. But because of resonance electron donation of a lone pair of electrons on the neighboring oxygen, enols are more electron- rich and correspondingly more reactive than alkenes. Notice in the following electrostatic potential map of ethenol (HC=CHOH) how there is a substantial amount of electron density on the α carbon.
When an alkene reacts with an electrophile, such as HCl, initial addition of H gives an intermediate cation and subsequent reaction with Cl yields an addition product. When an enol reacts with an electrophile, however, only the initial addition step is the same. Instead of reacting with CI to give an addition product, the intermediate cation loses the OH proton to give an α-substituted carbonyl compound. | 0 | Theoretical and Fundamental Chemistry |
Heteroduplex analysis (HDA) is a method in biochemistry used to detect point mutations in DNA (Deoxyribonucleic acid) since 1992. Heteroduplexes are dsDNA molecules that have one or more mismatched pairs, on the other hand homoduplexes are dsDNA which are perfectly paired. This method of analysis depend up on the fact that heteroduplexes shows reduced mobility relative to the homoduplex DNA. heteroduplexes are formed between different DNA alleles. In a mixture of wild-type and mutant amplified DNA, heteroduplexes are formed in mutant alleles and homoduplexes are formed in wild-type alleles. There are two types of heteroduplexes based on type and extent of mutation in the DNA. Small deletions or insertion create bulge-type heteroduplexes which is stable and is verified by electron microscope. Single base substitutions creates more unstable heteroduplexes called bubble-type heteroduplexes, because of low stability it is difficult to visualize in electron microscopy. HDA is widely used for rapid screening of mutation of the 3 bp p.F508del deletion in the CFTR gene. | 1 | Applied and Interdisciplinary Chemistry |
The Peregrine soliton (or Peregrine breather) is an analytic solution of the nonlinear Schrödinger equation. This solution was proposed in 1983 by Howell Peregrine, researcher at the mathematics department of the University of Bristol. | 1 | Applied and Interdisciplinary Chemistry |
Smelting involves more than just melting the metal out of its ore. Most ores are the chemical compound of the metal and other elements, such as oxygen (as an oxide), sulfur (as a sulfide), or carbon and oxygen together (as a carbonate). To extract the metal, workers must make these compounds undergo a chemical reaction. Smelting, therefore, consists of using suitable reducing substances that combine with those oxidizing elements to free the metal. | 1 | Applied and Interdisciplinary Chemistry |
Solar cells are typically named after the semiconducting material they are made of. These materials must have certain characteristics in order to absorb sunlight. Some cells are designed to handle sunlight that reaches the Earth's surface, while others are optimized for use in space. Solar cells can be made of a single layer of light-absorbing material (single-junction) or use multiple physical configurations (multi-junctions) to take advantage of various absorption and charge separation mechanisms.
Solar cells can be classified into first, second and third generation cells. The first generation cells—also called conventional, traditional or wafer-based cells—are made of crystalline silicon, the commercially predominant PV technology, that includes materials such as polysilicon and monocrystalline silicon. Second generation cells are thin film solar cells, that include amorphous silicon, CdTe and CIGS cells and are commercially significant in utility-scale photovoltaic power stations, building integrated photovoltaics or in small stand-alone power system. The third generation of solar cells includes a number of thin-film technologies often described as emerging photovoltaics—most of them have not yet been commercially applied and are still in the research or development phase. Many use organic materials, often organometallic compounds as well as inorganic substances. Despite the fact that their efficiencies had been low and the stability of the absorber material was often too short for commercial applications, there is research into these technologies as they promise to achieve the goal of producing low-cost, high-efficiency solar cells. As of 2016, the most popular and efficient solar cells were those made from thin wafers of silicon which are also the oldest solar cell technology. | 0 | Theoretical and Fundamental Chemistry |
Barium chloride is an inorganic compound with the formula . It is one of the most common water-soluble salts of barium. Like most other water-soluble barium salts, it is a white powder, highly toxic, and imparts a yellow-green coloration to a flame. It is also hygroscopic, converting to the dihydrate , which are colourless crystals with a bitter salty taste. It has limited use in the laboratory and industry. | 0 | Theoretical and Fundamental Chemistry |
Molecular phenotyping describes the technique of quantifying pathway reporter genes, i.e. pre-selected genes that are modulated specifically by metabolic and signaling pathways, in order to infer activity of these pathways.
In most cases, molecular phenotyping quantifies changes of pathway reporter gene expression to characterize modulation of pathway activities induced by perturbations such as therapeutic agents or stress in a cellular system in vitro. In such contexts, measurements at early time points are often more informative than later observations because they capture the primary response to the perturbation by the cellular system. Integrated with quantified changes of phenotype induced by the perturbation, molecular phenotyping can identify pathways that contribute to the phenotypic changes.
Currently molecular phenotyping uses RNA sequencing and mRNA expression to infer pathway activities. Other technologies and readouts such as mass spectrometry and protein abundance or phosphorylation levels can be potentially used as well. | 1 | Applied and Interdisciplinary Chemistry |
To demonstrate the specificity when developing stability indicating method.
To help to identify reactions that cause degradation of pharmaceutical product.
As a part of method development strategy.
Are designed to generate product related variants. | 1 | Applied and Interdisciplinary Chemistry |
In 1939, the Central Committee of the Chinese Communist Party decided to send a group of children of party revolutionaries to study in the Soviet Union. In November 1939 Liu and his sister Liu Aiqin arrived at the childrens home in Monino, where Mao Zedongs sons Mao Anying and Mao Anqing were also living. While in Soviet Union, Liu was known by Russian name Klim (Клим).
After one semester of study, Liu Yunbin moved to Interdom, which was 300 kilometers away from Moscow, at the city of Ivanovo, and was sponsored by the International Red Aid of the Soviet Union. During his time at the school, he studied very hard and in June 1941, following the start of the German invasion of the Soviet Union, Liu actively participated in the labors organized by the International Childrens Institute, such as land reclamation, logging, and moving firewood. He also took the initiative to donate blood for the Soviet Red Army soldiers fighting in the frontline. He was selected as one of the leaders of the International Childrens Institute student union, and soon joined the Komsomol and served as the head of the organization in the International Children's Academy.
After graduation from high school in 1945, Liu was admitted to the Moscow Iron and Steel Institute, where he majored in smelting. During his time in the institution, he also joined the Communist Party of the Soviet Union and after graduation, he was admitted to the Department of Chemistry at Moscow State University with honors and as a graduate student in radiochemistry. He graduated in 1955 with an associate doctorate degree and entered the Moscow University Institute of Chemistry as a senior researcher. In a 1955 letter to Liu Yunbin, Liu Shaoqi stated:
In 1957, he returned to China, where he resided in his father's residence in Zhongnanhai for a few days, before moving to Fangshan County, Shanxi, 50 kilometers away from Beijing, to work at the China Institute of Atomic Energy (Institute 401), which was one of the earliest nuclear weapons research institutes in China. He made outstanding contributions to nuclear energy research and was awarded the title of associate researcher.
In 1959, when Sino-Soviet relations deteriorated, the Soviet Union refused to provide China with technical materials required to develop the atomic bomb. In 1961, researchers from the First Institute of the China Institute of Atomic Energy were transferred to the China Nuclear Fuel Component Factory (Factory 202) at Baotou, Inner Mongolia Autonomous Region, where they set up a second laboratory, which was responsible for the research into thermonuclear materials.
In the winter of 1962, Liu Yunbin arrived at the 202 Factory, where he was appointed by his superiors as the director of the Second Research Office. The office under his leadership began research and organizational work for the atomic bomb project and, on 16 October 1964, China's first atomic bomb was successfully detonated at the Lop Nur test site, which resulted in China becoming the fifth nuclear power in the world and the first Asian nation to possess nuclear capability. | 0 | Theoretical and Fundamental Chemistry |
Some metal alkyls feature agostic interactions between a C-H bond on the alkyl group and the metal. Such interactions are especially common for complexes of early transition metals in their highest oxidation states.
One determinant of the kinetic stability of metal-alkyl complexes is the presence of hydrogen at the position beta to the metal. If such hydrogens are present and if the metal center is coordinatively unsaturated, then the complex can undergo beta-hydride elimination to form a metal-alkene complex:
These conversions are assumed to proceed via the intermediacy of agostic interactions. | 0 | Theoretical and Fundamental Chemistry |
Vertically mounted tubes of up to diameter extending from just above the base of a deep concrete tank to just below the surface of the sewage liquor. A typical shaft might be high. At the surface end, the tube is formed into a cone with helical vanes attached to the inner surface. When the tube is rotated, the vanes spin liquor up and out of the cones drawing new sewage liquor from the base of the tank. In many works, each cone is located in a separate cell that can be isolated from the remaining cells if required for maintenance. Some works may have two cones to a cell and some large works may have 4 cones per cell. | 1 | Applied and Interdisciplinary Chemistry |
The Mark IV Cell design was introduced in 2009. It included the following improvements:
* a flexible hose for easier alignment of the downcomer
* clamping of the slurry lens onto the downcomer (see Figure 10)
* stainless steel quick-release clamps in the downcomer assembly
* long-lasting rubber flaps in the AISE valves. | 1 | Applied and Interdisciplinary Chemistry |
Hydrides add to give hydroxylamines. Reducing Lewis acids (e.g. metals, Sulfur dioxide|) deoxygenate to the imine instead. | 0 | Theoretical and Fundamental Chemistry |
Different gases will have different mean free paths for molecules and electrons. This is because different molecules have ionization cross sections, that is, different effective diameters. Noble gases like helium and argon are monatomic harder to ionize and tend to have smaller effective diameters. This gives them greater mean free paths.
Ionization potentials differ between molecules, as well as the speed that they recapture electrons after they have been knocked out of orbit. All three effects change the number of collisions needed to cause an exponential growth in free electrons. These free electrons are necessary to cause an arc. | 0 | Theoretical and Fundamental Chemistry |
Dalton Transactions is a weekly peer-reviewed scientific journal covering original (primary) research and review articles on all aspects of the chemistry of inorganic, bioinorganic, and organometallic compounds. It is published by the Royal Society of Chemistry and the editor-in-chief is Russell Morris (University of St Andrews). The journal was named after the English chemist, John Dalton, best known for his work on modern atomic theory. The journal was named a "rising star" in 2006. | 0 | Theoretical and Fundamental Chemistry |
The Spallation Neutron Source (SNS) is an accelerator-based neutron source facility in the U.S. that provides the most intense pulsed neutron beams in the world for scientific research and industrial development. Each year, this facility hosts hundreds of researchers from universities, national laboratories, and industry, who conduct basic and applied research and technology development using neutrons. SNS is part of Oak Ridge National Laboratory, which is managed by UT-Battelle for the United States Department of Energy (DOE). SNS is a DOE Office of Science user facility, and it is open to scientists and researchers from all over the world. | 0 | Theoretical and Fundamental Chemistry |
Within the sciences, the word "contamination" can take on a variety of subtle differences in meaning, whether the contaminant is a solid or a liquid, as well as the variance of environment the contaminant is found to be in. A contaminant may even be more abstract, as in the case of an unwanted energy source that may interfere with a process. The following represent examples of different types of contamination based on these and other variances. | 0 | Theoretical and Fundamental Chemistry |
Devices used to sample the concentrations of particulates and compounds of the SML include a glass fabric, metal mesh screens, and other hydrophobic surfaces. These are placed on a rotating cylinder which collects surface samples as it rotates on top of the ocean surface.
The glass plate sampler is commonly used. It was first described in 1972 by Harvey and Burzell as a simple but effective method of collecting small sea surface microlayer samples. A clean glass plate is immersed vertically into the water and then withdrawn in a controlled manner. Harvey and Burzell used a plate which was 20 cm square and 4 mm thick. They withdrew it from the sea at the rate of 20 cm per second. Typically the uppermost 20–150 µm of the surface microlayer adheres to the plate as it is withdrawn. The sample is then wiped from both sides of the plate into a sampling vial.
For a plate of the size used by Harvey and Burzel, the resulting sample volumes are between about 3 and 12 cubic centimetres. The sampled SML thickness h in micrometres is given by:
where V is the sample volume in cm, A is the total immersed plate area of both sides in cm, and N is the number of times the sample was dipped. | 0 | Theoretical and Fundamental Chemistry |
Levetiracetam, sold under the brand name Keppra among others, is a medication used to treat epilepsy. It is used for partial-onset, myoclonic, or tonic–clonic seizures and is taken either by mouth as an immediate or extended release formulation or by injection into a vein.
Common side effects of levetiracetam include sleepiness, dizziness, feeling tired, and aggression. Severe side effects may include psychosis, suicide, and allergic reactions such as Stevens–Johnson syndrome or anaphylaxis. Levetiracetam is the S-enantiomer of etiracetam. Its mechanism of action is not yet clear.
Levetiracetam was approved for medical use in the United States in 1999 and is available as a generic medication. In 2021, it was the 101st most commonly prescribed medication in the United States, with more than 6million prescriptions. It is on the World Health Organization's List of Essential Medicines. | 0 | Theoretical and Fundamental Chemistry |
URhGes critical temperature (T') is normally about 280 millikelvins.
The Grenoble team in France, headed by Andrew D. Huxley, first cooled down the sample below its critical temperature and raised the magnetic field to 2 T. As expected, the sample's superconducting properties vanished. However, when the team raised the magnetic field to 8 T, the superconducting behavior continued. The critical temperature at that field strength increased to about 400 millikelvins. The sample retained the superconducting state until 13 T. They also found that at 12 T, the URhGe sample experienced a magnetic phase transition. | 1 | Applied and Interdisciplinary Chemistry |
* Orbifold signature:
* Coxeter notation (rectangular): [∞,2,∞] or [∞]×[∞]
* Coxeter notation (square): [4,1,4] or [1,4,4,1]
* Lattice: rectangular
* Point group: D
* The group pmm has reflections in two perpendicular directions, and four rotation centres of order two (180°) located at the intersections of the reflection axes.
;Examples of group pmm | 0 | Theoretical and Fundamental Chemistry |
Application of BNAs include small RNA research; design and synthesis of RNA aptamers; siRNA; antisense probes; diagnostics; isolation; microarray analysis; Northern blotting; real-time PCR; in situ hybridization; functional analysis; SNP detection and use as antigens and many others nucleotide base applications. | 1 | Applied and Interdisciplinary Chemistry |
Hardness can be quantified by instrumental analysis. The total water hardness is the sum of the molar concentrations of Ca and Mg, in mol/L or mmol/L units. Although water hardness usually measures only the total concentrations of calcium and magnesium (the two most prevalent divalent metal ions), iron, aluminium, and manganese are also present at elevated levels in some locations. The presence of iron characteristically confers a brownish (rust-like) colour to the calcification, instead of white (the colour of most of the other compounds).
Water hardness is often not expressed as a molar concentration, but rather in various units, such as degrees of general hardness (dGH), German degrees (°dH), parts per million (ppm, mg/L, or American degrees), grains per gallon (mpg), English degrees (°e, e, or °Clark), or French degrees (°fH, °f or °HF; lowercase f is used to prevent confusion with degrees Fahrenheit). The table below shows conversion factors between the various units.
The various alternative units represent an equivalent mass of calcium oxide (CaO) or calcium carbonate (CaCO) that, when dissolved in a unit volume of pure water, would result in the same total molar concentration of Mg and Ca. The different conversion factors arise from the fact that equivalent masses of calcium oxide and calcium carbonates differ and that different mass and volume units are used. The units are as follows:
* Parts per million (ppm) is usually defined as 1 mg/L CaCO (the definition used below). It is equivalent to mg/L without chemical compound specified, and to American degree.
* Grain per gallon (gpg) is defined as 1 grain (64.8 mg) of calcium carbonate per U.S. gallon (3.79 litres), or 17.118 ppm.
* a mmol/L is equivalent to 100.09 mg/L CaCO or 40.08 mg/L Ca.
* A degree of General Hardness (dGH or German degree (°dH, deutsche Härte)) is defined as 10 mg/L CaO or 17.848 ppm.
* A Clark degree (°Clark) or English degrees (°e or e) is defined as one grain (64.8 mg) of CaCO per Imperial gallon (4.55 litres) of water, equivalent to 14.254 ppm.
* A French degree (°fH or °f) is defined as 10 mg/L CaCO, equivalent to 10 ppm. | 0 | Theoretical and Fundamental Chemistry |
Changing the concentration of a chemical will shift the equilibrium to the side that would counter that change in concentration. The chemical system will attempt to partly oppose the change affected to the original state of equilibrium. In turn, the rate of reaction, extent, and yield of products will be altered corresponding to the impact on the system.
This can be illustrated by the equilibrium of carbon monoxide and hydrogen gas, reacting to form methanol.
:CO + 2 H ⇌ CHOH
Suppose we were to increase the concentration of CO in the system. Using Le Chatelier's principle, we can predict that the concentration of methanol will increase, decreasing the total change in CO. If we are to add a species to the overall reaction, the reaction will favor the side opposing the addition of the species. Likewise, the subtraction of a species would cause the reaction to "fill the gap" and favor the side where the species was reduced. This observation is supported by the collision theory. As the concentration of CO is increased, the frequency of successful collisions of that reactant would increase also, allowing for an increase in forward reaction, and generation of the product. Even if the desired product is not thermodynamically favored, the end-product can be obtained if it is continuously removed from the solution.
The effect of a change in concentration is often exploited synthetically for condensation reactions (i.e., reactions that extrude water) that are equilibrium processes (e.g., formation of an ester from carboxylic acid and alcohol or an imine from an amine and aldehyde). This can be achieved by physically sequestering water, by adding desiccants like anhydrous magnesium sulfate or molecular sieves, or by continuous removal of water by distillation, often facilitated by a Dean-Stark apparatus. | 0 | Theoretical and Fundamental Chemistry |
T.V. (Babu) RajanBabu is an organic chemist who holds the position of Distinguished Professor of Chemistry in the College of Arts and Sciences at the Ohio State University. His laboratory traditionally focuses on developing transition metal-catalyzed reactions. RajanBabu is known for helping develop the Nugent-RajanBabu reagent (Bis(cyclopentadienyl)titanium(III) chloride), a chemical reagent used in synthetic organic chemistry as a single electron reductant. | 0 | Theoretical and Fundamental Chemistry |
The Corby toxic waste case was a court case decided by The Hon. Mr. Justice Akenhead at the High Court of Justice, London, on 29 July 2009 in the case of Corby Group Litigation v. Corby Borough Council [2009] EWHC 1944 (TCC). The judge found Corby Borough Council liable in negligence, public nuisance and a breach of statutory duty for its reclamation of a Corby Steelworks in the town of Corby, Northamptonshire, between 1985 and 1997. The landmark decision was historically significant as the first in the world to establish a link between atmospheric toxic waste and birth defects - all previous cases have involved water pollution - and held implications for other council reclamation programs and the methods of conducting reclamation in England and Wales.
The case has been described as "the British Erin Brockovich". | 1 | Applied and Interdisciplinary Chemistry |
Although nonsense-mediated mRNA decay reduces nonsense codons, mutations can occur that lead to various health problems and diseases in humans. A dominant-negative or deleterious gain-of-function mutation can occur if premature terminating (nonsense) codons are translated. NMD is becoming increasingly evident in the way it modifies phenotypic consequences because of the broad way it controls gene expression. For instance, the blood disorder Beta thalassemia is inherited and caused by mutations within the upstream region of the β-globin gene. An individual carrying only one affected allele will have no or extremely low levels of the mutant β-globin mRNA. An even more severe form of the disease can occur called thalassemia intermedia or ‘inclusion body’ thalassemia. Instead of decreased mRNA levels, a mutant transcript produces truncated β chains, which in turn leads to a clinical phenotype in the heterozygote.
Nonsense-mediated decay mutations can also contribute to Marfan syndrome. This disorder is caused by mutations in the fibrillin 1 (FBN1) gene and is resulted from a dominant negative interaction between mutant and wild-type fibrillin-1 gene. | 1 | Applied and Interdisciplinary Chemistry |
hair cell - half-life - halobacteria - halotolerance - haploid - heat of fusion - heat of vaporization - heat shock protein - Hsp70 (70 kDa heat shock proteins) - Hsp90 (90 kDa heat shock proteins) - heavy-chain immunoglobulin - Hela cell - helminth protein - helper T cell - hemopexin - hemoglobin - herpes simplex virus protein vmw65 - heterocyclic compound - heterotroph - heterozygote - Hfr cell - Hill reaction - His tag - histamine H1 receptor - histamine H2 receptor - histamine receptor - histidine - histone - history of science and technology - HIV receptor - holoenzyme - homeobox - homeodomain protein - homology - homoserine - homozygote - homunculus - hormone - housekeeping gene - Human Genome Project - hybridization - hydrocarbon - hydrogen - hydrogen bond - hydrogenation - hydrogen-deuterium exchange - hydrolysis - hydrolytic enzyme - hydrophilic - hydrophobe - hydrophobic - hydrophobicity analysis - hydroxyl | 1 | Applied and Interdisciplinary Chemistry |
Ahmet Turgay Uzer is a Turkish-born American theoretical physicist and nature photographer.
Regents' Professor Emeritus at Georgia Institute of Technology following Joseph Ford (physicist). He has contributed in the field of atomic and molecular physics, nonlinear dynamics and chaos significantly. His research on interplay between quantum dynamics
and classical mechanics, in the context of chaos is considered to be novel in molecular and theoretical physics and chemistry. | 0 | Theoretical and Fundamental Chemistry |
Despite the varieties of impressions, interpretations and opinions expressed by translators, the meditation technique described by The Secret of the Golden Flower is a straightforward, silent method; the book's description of meditation has been characterized as "Zen with details". The meditation technique, set forth in poetic language, reduces to a formula of sitting, breathing, and contemplating.
Christopher Cott and Adam Rock describe it in the context of Taoist doctrine. The practice involves meditative exercises on the spiritual soul (hun) and the primordial spirit. In contrast to the material soul (po), the spirit soul resides in the heavenly heart-mind (xin) and is the Yang qi obtained from the cosmos. It is described as a house where "the light" is the master, being the stage for the "turning the light around". The procedure consists in refining the material soul and interrupting conceptual thought (of the world of the senses) through this meditation; thus, the true nature of the primordial spirit would be revealed. Practitioners should be aware of states such as "submersion in darkness" (cessation of conceptual thinking). They summarize the work in three stages: the initial stage is "harmonizing the breath", in which the conceptual mind still predominates, but the breath in the heart-mind and the heart-mind in the breath are used to calm this awareness. A second stage involves energetic and mental aspects (a metaphor of the interaction between Water and Fire). The third stage ("turning the light around") is finalized by the culmination of mental quiescence, the spirit incubating in qi ("Heaven entering Earth").
Sitting primarily relates to a straight posture. Breathing is described in detail, primarily in terms of the esoteric physiology of the path of qi (also known as chi or ki). The energy path associated with breathing has been described as similar to an internal wheel vertically aligned with the spine. When breathing is steady, the wheel turns forward, with breath energy rising in back and descending in front. Bad breathing habits (or bad posture, or even bad thoughts) may cause the wheel not to turn, or move backward, inhibiting the circulation of essential breath energy. In contemplation, one watches thoughts as they arise and recede.
The meditation technique is supplemented by descriptions of affirmations of progress in the course of a daily practice, suggesting stages that could be reached and phenomenon that may be observed such as a feeling of lightness, like floating upward or slight levitation. Such benefits are ascribed to improved internal energy associated with breath energy circulation, improvements that alleviate previously existing impediments. Several drawings portray imagery relevant to the personal evolution of a meditation practitioner, images that may be somewhat confusing in terms of pure rational analysis. "Only after one hundred days of consistent work, only then is the light genuine; only then can one begin to work with the spirit-fire."
The first such illustration represents the first one hundred days, or "gathering the light". The second one represents an emergence of meditative consciousness. The third stage represents a meditative awareness that exists even in mundane, daily life. Stage four represents a higher meditative perception, where all conditions are recognized. Then, varied conditions are portrayed as separately perceived, yet each separate perception is part of a whole of awareness. | 1 | Applied and Interdisciplinary Chemistry |
The "black box" in the title refers to the conceptual tool in which, for one reason or another, the internal workings of a device are taken for granted, so that its function may be discussed. The philosophical tool is commonly used in scientific discourse, and Behe notes that understandings of cellular structure and other aspects of microbiology were not much understood when Charles Darwin was alive. He then states that he plans to delve into the issue.
Behe begins by reminding the general reader of paradigm shifts in the history of science, in which the foundations and assumptions of theories are examined, sometimes resulting in the rejection of an entire past theory. Behe suggests that such a paradigm shift in biology (and particularly in evolution) is imminent due to recent discoveries (circa 1996) in biochemistry. Behe acknowledges acceptance of the theory of evolution by "the great majority" of scientists, and he states that "most (though not all) do so based on authority."
Behe states that elucidations of the evolutionary history of various biological features typically assume the existence of certain abilities as their starting point, such as Charles Darwins example of a cluster of light-sensitive spots evolving into an eye via a series of intermediate steps. He then points out that Darwin dismissed the need to explain the origin of the simple' light-sensitive spot, summarizes the modern understanding of the biochemistry of vision and claims that many other evolutionary explanations face a similar challenge.
Behe next introduces and defines the concept of irreducible complexity as a system with a series of parts in which the removal of any part causes the entire system to cease functioning, offering a spring-loaded bar mousetrap as a familiar example. In the following chapters, Behe discusses the apparent irreducible complexity of several biological systems, including the cilium, the bacterial flagellum, blood clotting, the immune system, and vesicular transport. Behe claims the underlying complexity and biochemical mechanisms of the systems are vastly under-appreciated, and identifies other, similar systems.
Behe identifies one of the primary counter-arguments of irreducible complexity, gradual adaptation—that certain systems may have been co-opted from an original, unrelated role to assume a new function as an irreducibly complex system. He counter-argues that though it is impossible to consider all possible roles for any component, it is extremely implausible that components can fortuitously change function within a complex system and that the focus of the theory changes from making to modifying components and recounts unsuccessful attempts to discover evolutionary pathways for complex systems within scientific journals. Behe states that though he did identify assertions that evolution had occurred, he found none that had been supported by experiment or calculation, and concludes the book by offering intelligent design as a solution to irreducible complexity. | 1 | Applied and Interdisciplinary Chemistry |
The carbylamine reaction (also known as the Hoffmann isocyanide synthesis) is the synthesis of an isocyanide by the reaction of a primary amine, chloroform, and base. The conversion involves the intermediacy of dichlorocarbene.
Illustrative is the synthesis of tert-butyl isocyanide from tert-butylamine in the presence of catalytic amount of the phase transfer catalyst benzyltriethylammonium chloride.
:MeCNH + CHCl + 3 NaOH → MeCNC + 3 NaCl + 3 HO
Similar reactions have been reported for aniline. It is used to prepare secondary amines. | 0 | Theoretical and Fundamental Chemistry |
Enzyme-mediated (biological) chiral inversion of organic compounds is caused by highly chiral endogenous molecules found in receptors, enzymes, and other structures. While enzyme inhibitors suppress enzyme activity, enzyme inducers boost enzyme concentration and activity. The primary determinants of inter-individual variability in drug metabolism in humans are thought to include genetic polymorphism and a variety of other variables, including age, gender, biological conditions, pregnancy, illnesses, stress, nutrition, and drugs. For instance, Reichel et al. reported that a 2-arylpropionyl-coenzyme-A epimerase was molecularly cloned and expressed as a crucial enzyme in the inversion metabolism of ibuprofen. Ibuprofen's chiral inversion by enzymes has been documented in humans. | 0 | Theoretical and Fundamental Chemistry |
The interplay of molecular scale mechanisms and hierarchical surface structures is known to result in high levels of static friction and bonding between pairs of surfaces. Technologically advanced adhesive devices sometimes make use of microstructures on surfaces, such as tightly packed periodic posts. These are biomimetic technologies inspired by the adhesive abilities of the feet of various arthropods and vertebrates (most notably, geckos). By intermixing periodic breaks into smooth, adhesive surfaces, the interface acquires valuable crack-arresting properties. Because crack initiation requires much greater stress than does crack propagation, surfaces like these are much harder to separate, as a new crack has to be restarted every time the next individual microstructure is reached. | 0 | Theoretical and Fundamental Chemistry |
For example, to find the K value of methane at 100 psia and 60 °F.
# On the left-hand vertical axis, locate and mark the point containing the pressure 100 psia.
# On the right-hand vertical axis, locate and mark the point containing the temperature 60°F.
# Connect the points with a straight line.
# Note where the line crosses the methane axis. Read this K-value off the chart (approximately 21.3). | 1 | Applied and Interdisciplinary Chemistry |
A circular filter paper is taken and the sample is deposited at the center of the paper. After drying the spot, the filter paper is tied horizontally on a Petri dish containing solvent, so that the wick of the paper is dipped in the solvent. The solvent rises through the wick and the components are separated into concentric rings. | 0 | Theoretical and Fundamental Chemistry |
*Estimation of the size of DNA molecules following digestion with restriction enzymes, e.g., in restriction mapping of cloned DNA.
*Estimation of the DNA concentration by comparing the intensity of the nucleic acid band with the corresponding band of the size marker.
*Analysis of products of a polymerase chain reaction (PCR), e.g., in molecular genetic diagnosis or genetic fingerprinting
*Separation of DNA fragments for extraction and purification.
*Separation of restricted genomic DNA prior to Southern transfer, or of RNA prior to Northern transfer.
*Separation of proteins, for example, screening of protein abnormalities in clinical chemistry.
Agarose gels are easily cast and handled compared to other matrices and nucleic acids are not chemically altered during electrophoresis. Samples are also easily recovered. After the experiment is finished, the resulting gel can be stored in a plastic bag in a refrigerator.
Electrophoresis is performed in buffer solutions to reduce pH changes due to the electric field, which is important because the charge of DNA and RNA depends on pH, but running for too long can exhaust the buffering capacity of the solution. Further, different preparations of genetic material may not migrate consistently with each other, for morphological or other reasons. | 1 | Applied and Interdisciplinary Chemistry |
The ability of geckos – which can hang on a glass surface using only one toe – to climb on sheer surfaces has been for many years mainly attributed to the van der Waals forces between these surfaces and the spatulae, or microscopic projections, which cover the hair-like setae found on their footpads.
There were efforts in 2008 to create a dry glue that exploits the effect, and success was achieved in 2011 to create an adhesive tape on similar grounds (i.e. based on van der Waals forces). In 2011, a paper was published relating the effect to both velcro-like hairs and the presence of lipids in gecko footprints.
A later study suggested that capillary adhesion might play a role, but that hypothesis has been rejected by more recent studies.
A 2014 study has shown that gecko adhesion to smooth Teflon and polydimethylsiloxane surfaces is mainly determined by electrostatic interaction (caused by contact electrification), not van der Waals or capillary forces.
Among the arthropods, some spiders have similar setae on their scopulae or scopula pads, enabling them to climb or hang upside-down from extremely smooth surfaces such as glass or porcelain. | 0 | Theoretical and Fundamental Chemistry |
Noncovalent intermolecular interactions, albeit individually small, collectively alter chemical reactions in major ways. Listed below are common intermolecular forces that chemists have used to design foldamers.
* Hydrogen bonding (especially with peptide bonds)
* Pi stacking
* Solvophobic effects, which lead to hydrophobic collapse
* Van der Waals forces
* Electrostatic attraction | 0 | Theoretical and Fundamental Chemistry |
In crystallography, the diamond cubic crystal structure is a repeating pattern of 8 atoms that certain materials may adopt as they solidify. While the first known example was diamond, other elements in group 14 also adopt this structure, including α-tin, the semiconductors silicon and germanium, and silicon–germanium alloys in any proportion. There are also crystals, such as the high-temperature form of cristobalite, which have a similar structure, with one kind of atom (such as silicon in cristobalite) at the positions of carbon atoms in diamond but with another kind of atom (such as oxygen) halfway between those (see :Category:Minerals in space group 227).
Although often called the diamond lattice, this structure is not a lattice in the technical sense of this word used in mathematics. | 0 | Theoretical and Fundamental Chemistry |
The reaction is:
The reaction is an exothermic equilibrium reaction in which the gas volume is reduced. The equilibrium constant K of the reaction (see table) and obtained from:
Since the reaction is exothermic, the equilibrium of the reaction shifts at lower temperatures to the ammonia side. Furthermore, four volumetric units of the raw materials produce two volumetric units of ammonia. According to Le Chatelier's principle, higher pressure favours ammonia. High pressure is necessary to ensure sufficient surface coverage of the catalyst with nitrogen. For this reason, a ratio of nitrogen to hydrogen of 1 to 3, a pressure of 250 to 350 bar, a temperature of 450 to 550 °C and α iron are optimal.
The catalyst ferrite (α-Fe) is produced in the reactor by the reduction of magnetite with hydrogen. The catalyst has its highest efficiency at temperatures of about 400 to 500 °C. Even though the catalyst greatly lowers the activation energy for the cleavage of the triple bond of the nitrogen molecule, high temperatures are still required for an appropriate reaction rate. At the industrially used reaction temperature of 450 to 550 °C an optimum between the decomposition of ammonia into the starting materials and the effectiveness of the catalyst is achieved. The formed ammonia is continuously removed from the system. The volume fraction of ammonia in the gas mixture is about 20%.
The inert components, especially the noble gases such as argon, should not exceed a certain content in order not to reduce the partial pressure of the reactants too much. To remove the inert gas components, part of the gas is removed and the argon is separated in a gas separation plant. The extraction of pure argon from the circulating gas is carried out using the Linde process. | 0 | Theoretical and Fundamental Chemistry |
Several photons of energy below the ionization threshold may actually combine their energies to ionize an atom. This probability decreases rapidly with the number of photons required, but the development of very intense, pulsed lasers still makes it possible. In the perturbative regime (below about 10 W/cm at optical frequencies), the probability of absorbing N photons depends on the laser-light intensity I as I. For higher intensities, this dependence becomes invalid due to the then occurring AC Stark effect.
Resonance-enhanced multiphoton ionization (REMPI) is a technique applied to the spectroscopy of atoms and small molecules in which a tunable laser can be used to access an excited intermediate state.
Above-threshold ionization (ATI) is an extension of multi-photon ionization where even more photons are absorbed than actually would be necessary to ionize the atom. The excess energy gives the released electron higher kinetic energy than the usual case of just-above threshold ionization. More precisely, the system will have multiple peaks in its photoelectron spectrum which are separated by the photon energies, indicating that the emitted electron has more kinetic energy than in the normal (lowest possible number of photons) ionization case. The electrons released from the target will have approximately an integer number of photon-energies more kinetic energy. | 0 | Theoretical and Fundamental Chemistry |
The Berlin Graduate School of Natural Sciences and Engineering (BIG-NSE) is part of the Cluster of Excellence "Unifying Concepts in Catalysis" (UniCat) founded in November 2007 by the Technical University of Berlin and five further institutions in the Berlin area within the framework of the German government‘s Excellence Initiative.
The main research interest of the UniCat and BIG-NSE Faculty is Catalysis, in a broad sense. The research fields involved cover a broad range of topics, from natural sciences to engineering. The faculty consists of professors and junior researchers from 54 research groups at 6 participating institutions and active in 13 research fields, who will be intensively involved in the supervision and mentoring of the BIG-NSE students, among them the Fritz Haber Institute of the Max Planck Society, the working place of Professor Gerhard Ertl, the winner of the Nobel Prize in Chemistry 2007. | 1 | Applied and Interdisciplinary Chemistry |
Section B on Thermodynamics, Equipment and Systems of the IIR focuses on the technological and scientific fundamentals of classical refrigeration, excluding cryogenic temperatures. The fundamentals are represented by its Commission B1 Thermodynamics and Transfer Processes whereas Commission B2 Refrigerating Equipment covers all kinds of refrigeration technology. Section B is a key player in most of the IIR international conferences; except for the International Conference of Refrigeration (ICR) organised every four years for all 10 IIR Commissions, where approximately 50% of all presentations are related to Section B topics.
Independently, and together with other Sections, Section B hosts a multitude of conferences such as the Gustav Lorentzen Conference on Natural Working Fluids and the Ohrid Conference on Ammonia and Refrigeration Technologies; or conferences on Thermodynamic Properties and Transfer Processes of Refrigerants, on Magnetic Refrigeration at Room Temperature, on Compressors and Coolants, and on Phase Change Materials and Slurries for Refrigeration and Air Conditioning.
A number of Working Groups, where emerging topics in refrigeration are discussed by IIR experts with the aim of publishing results in handbooks or other forms publications, are organised within the scope of Section B. Main topics include mitigation of direct emissions of greenhouse gases in refrigeration, refrigerant charge reduction in refrigerating systems, magnetic cooling, life cycle climate performance evaluation, and refrigerant system safety.
* Commission B1: Thermodynamics and Transfer Processes
The objectives of Commission B1 on Thermodynamics and Transfer Processes are to provide academic and industrial information and data, and to propose any solutions on thermodynamics and transfer processes. The Commission B1 has been extremely active in IIR Working Groups, sub-commissions, IIR conferences and co-sponsored conferences and commission business meetings.
As well as being involved in IIR Working Groups on the mitigation of direct emissions of greenhouse gases in refrigeration, the commission is equally involved in the Working Group on Life Cycle Climate Performance (LCCP) Evaluation.
Active in IIR conferences and congresses, Commission B1 similarly organises workshops in various fields such as refrigerant charge reduction in refrigerating systems. Initiatives and opportunities, such as the phase-down of high-GWP refrigerants, energy-efficient buildings and cars, transport refrigeration, food preservation, the economic importance of the refrigeration sector, the involvement of the younger generation and identifying industrial needs are all at the heart of Commission B1.
* Commission B2: Refrigerating Equipment
Commission B2 Refrigerating Equipment participates in many IIR activities aimed at promoting knowledge of refrigeration technologies and their applications worldwide. It is a key Commission for most IIR activities synergizing with other Commissions. The Commission is very active in various IIR Working Groups on Magnetic Cooling and Refrigeration Safety. | 0 | Theoretical and Fundamental Chemistry |
The overall process of corrosion can be represented by a bimodal function, where the type of corrosion varies with time, including both oxygen-driven and anaerobic mechanisms. The dominant process will depend on the given conditions. During oxygen-driven corrosion, layers of rust form, creating various non-homogenous anoxic niches throughout the metal's surface. Within the niches the diffusion of oxygen is inhibited, leading to the ideal conditions for anaerobic corrosion to occur. | 1 | Applied and Interdisciplinary Chemistry |
Magma oceans are vast fields of surface magma that exist during periods of a planets or some natural satellites accretion when the celestial body is completely or partly molten.
In the early Solar System, magma oceans were formed by the melting of planetesimals and planetary impacts. Small planetesimals are melted by the heat provided by the radioactive decay of aluminium-26. As planets grew larger, the energy was then supplied from giant impacts with other planetary bodies. Magma oceans are integral parts of planetary formation as they facilitate the formation of a core through metal segregation and an atmosphere and hydrosphere through degassing. Evidence exists to support the existence of magma oceans on both the Earth and the Moon. Magma oceans may survive for millions to tens of millions of years, interspersed by relatively mild conditions. | 0 | Theoretical and Fundamental Chemistry |
A rotating tank is a device used for fluid dynamics experiments. Typically cylinders filled with water on a rotating platform, the tanks can be used in various ways to simulate the atmosphere or ocean.
For example, a rotating tank with an ice bucket in the center can represent the Earth, with a cold pole simulated by the ice bucket. Just as in the atmosphere, eddies and a westerly jetstream form in the water. | 1 | Applied and Interdisciplinary Chemistry |
*Leland Hartwell et al.. 2004. Genetics – From Genes to Genomes 2nd Ed. McGraw-Hill
*Engels, W. R. [https://web.archive.org/web/20060111010249/http://engels.genetics.wisc.edu/Pelements/Pt.html P Elements in Drosophila] | 1 | Applied and Interdisciplinary Chemistry |
The bacteriophages used for cloning are the λ phage and M13 phage. There is an upper limit on the amount of DNA that can be packed into a phage (a maximum of 53 kb), therefore to allow foreign DNA to be inserted into phage DNA, phage cloning vectors may need to have some non-essential genes deleted, for example the genes for lysogeny since using phage λ as a cloning vector involves only the lytic cycle. There are two kinds of λ phage vectors - insertion vector and replacement vector. Insertion vectors contain a unique cleavage site whereby foreign DNA with size of 5–11 kb may be inserted. In replacement vectors, the cleavage sites flank a region containing genes not essential for the lytic cycle, and this region may be deleted and replaced by the DNA insert in the cloning process, and a larger sized DNA of 8–24 kb may be inserted.
There is also a lower size limit for DNA that can be packed into a phage, and vector DNA that is too small cannot be properly packaged into the phage. This property can be used for selection - vector without insert may be too small, therefore only vectors with insert may be selected for propagation. | 1 | Applied and Interdisciplinary Chemistry |
There are some main areas of focus that can be looked at for the future of SVA to keep improving and being innovational in technology. Firstly, the chambers in which SVA takes place should continue to be improved on to allow precision of the process, as well as, reproducibility of the same structure on each attempt. The focus on these chambers and the components that make it precise have been a hypothetical thought process of what parameters affect reproducibility. It is imperative to continue to improve the amount of control over the annealing through being able to control all factors, such as humidity and temperature. The point of being meticulous in defining such parameters is for the possibility of multiple labs reproducing a certain compound to the same effect.
Next off, SVA with the improvement of the apparatus in which the process takes place, in situ studies, through X-ray and neutron scattering methods, can give more highly accurate images of the swollen and dried states of the BCP. Using methods such as also ellipsometry and interferometry can lead to discoveries about the thickness of the polymers in different states and nanostructure orientation, which will help to learn more about the equilibrium structure and the kinetics of developing a specified morphology. It is important here as well to be able to define small molecule additions to different parts of the block polymer at different points of the annealing and evaporation as to accurately be able to precisely know how the moieties will create certain orientations and directionality in structure. The final area moving forward is simply the implementation of the created block polymers in new intended applications and technology, beyond lab study and characterization of the method. It is important to go beyond creating the nanostructures and move into seeing the utility of the structures in an application, which will help reveal practical shortcomings of the created polymers and reveal areas of where to improve in parts of the structure, such as film integrity and attachment strength of the amorphous chains. Going beyond these simple surface imaging will allow us to realize and face some of the dangers and hindrances to functionality, such as the toxicity of working with organic solvents or the issues with dewetting the swollen state of the BCP. | 0 | Theoretical and Fundamental Chemistry |
EWGs enhance the Lewis acidity, making compounds more reactive as Lewis acids. For example, fluorine is a stronger electron-withdrawing substituent than methyl, resulting in an increased Lewis acidity of boron trifluoride relative to trimethylborane. Electron-withdrawing groups also tend to reduce Lewis basicity. | 0 | Theoretical and Fundamental Chemistry |
Protein nanocages are natural nanocarriers composed of protein subunits with a porous structure. They benefit from monodispersity, intrinsic high stability for protection of internalized drugs from enzymatic degradation and controllable assembly for cargo loading and release.
However, their application might be blocked by immunogenicity, broad biodistribution and significant function and property variations. The incorporation of polymer chains by performing in situ ATRP on the outer surface of or inside the protein nanocages can be an effective way to mitigate those drawbacks. For example, increased loading density of cargo molecules and enhanced stability of the cage assembly can be obtained via internal ATRP inside the cavity of the virus capsid.
Beyond virus type particles, large multimeric proteins such as the iron storage protein ferritin have emerged as attractive tools to be used as well-defined nano-containers. Using a grafting from strategy, polymers can be introduced to ferritin in a highly regular fashion for precise spatial control. These polymer–ferritin constructs exhibited protease resistance, enabling longer retention time within the bloodstream while reducing possible antibody interactions. | 1 | Applied and Interdisciplinary Chemistry |
Today the basic ideas established by Leonardo are the same; the flow must be seeded with particles that can be observed by the method of choice. The seeding particles depend on many factors including the fluid, the sensing method, the size of the measurement domain, and sometimes the expected accelerations in the flow. If the flow contains particles that can be measured naturally, seeding the flow is unnecessary.
Spatial reconstruction of fluid streamtubes using long exposure imaging of tracer can be applied for streamlines imaging velocimetry, high resolution frame rate free velocimetry of stationary flows. Temporal integration of velocimetric information can be used to totalize fluid flow. For measuring velocity and length on moving surfaces, laser surface velocimeters are used.
The fluid generally limits the particle selection according to its specific gravity; the particles should ideally be of the same density as the fluid. This is especially important in flows with a high acceleration (for example, high-speed flow through a 90-degree pipe elbow). Heavier fluids like water and oil are thus very attractive to velocimetry, whereas air ads a challenge in most techniques that it is rarely possible to find particles of the same density as air.
Still, even large-field measurement techniques like PIV have been performed successfully in air. Particles used for seeding can be both liquid droplets or solid particles. Solid particles being preferred when high particle concentrations are necessary. For point measurements like laser Doppler velocimetry, particles in the nanometre diameter range, such as those in cigarette smoke, are sufficient to perform a measurement.
In water and oil there are a variety of inexpensive industrial beads that can be used, such as silver-coated hollow glass spheres manufactured to be conductive powders (tens of micrometres diameter range) or other beads used as reflectors and texturing agents in paints and coatings. The particles need not be spherical; in many cases titanium dioxide particles can be used. | 1 | Applied and Interdisciplinary Chemistry |
Genetically modified fish are used for scientific research, as pets and as a food source. Aquaculture is a growing industry, currently providing over half the consumed fish worldwide. Through genetic engineering it is possible to increase growth rates, reduce food intake, remove allergenic properties, increase cold tolerance and provide disease resistance. Fish can also be used to detect aquatic pollution or function as bioreactors.
Several groups have been developing zebrafish to detect pollution by attaching fluorescent proteins to genes activated by the presence of pollutants. The fish will then glow and can be used as environmental sensors. The GloFish is a brand of genetically modified fluorescent zebrafish with bright red, green, and orange fluorescent color. It was originally developed by one of the groups to detect pollution, but is now part of the ornamental fish trade, becoming the first genetically modified animal to become publicly available as a pet when in 2003 it was introduced for sale in the USA.
GM fish are widely used in basic research in genetics and development. Two species of fish, zebrafish and medaka, are most commonly modified because they have optically clear chorions (membranes in the egg), rapidly develop, and the one-cell embryo is easy to see and microinject with transgenic DNA. Zebrafish are model organisms for developmental processes, regeneration, genetics, behavior, disease mechanisms and toxicity testing. Their transparency allows researchers to observe developmental stages, intestinal functions and tumour growth. The generation of transgenic protocols (whole organism, cell or tissue specific, tagged with reporter genes) has increased the level of information gained by studying these fish.
GM fish have been developed with promoters driving an over-production of growth hormone for use in the aquaculture industry to increase the speed of development and potentially reduce fishing pressure on wild stocks. This has resulted in dramatic growth enhancement in several species, including salmon, trout and tilapia. AquaBounty Technologies, a biotechnology company, have produced a salmon (called AquAdvantage salmon) that can mature in half the time as wild salmon. It obtained regulatory approval in 2015, the first non-plant GMO food to be commercialized. As of August 2017, GMO salmon is being sold in Canada. Sales in the US started in May 2021. | 1 | Applied and Interdisciplinary Chemistry |
* 2023: Ho-Am Prize in Science chemistry and life sciences
* 2019 UW-Madison Villas Faculty Mid-Career Investigator Award
* 2018 Michigan State University Alumni Lectureship Award
* 2018 Student Selected ECS Speaker (Indiana University)
* 2017 MIT Student-Invited Inorganic Seminar Speaker
* 2016 UW-Madison Villas Associate Award
* 2015 Wisconsin Alumni Research Foundation (WARF) Innovation Award
* 2015 Camille and Henry Dreyfus Environmental Chemistry Mentor
* 2014 University Housing Honored Instructor
* 2014 Speaker for the Stanford Distinguished Women in Science Colloquia Series
* 2014 Chair, Gordon Research Conference-Electrodeposition
* 2013 Kavli Frontiers of Science Fellow (National Academy of Sciences)
* 2011 Chair, ACS-Division of Inorganic Chemistry, Solid State Subdivision
* 2011 Volume Organizer of Materials Research Society Bulletin
* 2011 University Faculty Scholar, Purdue University
* 2010 Iota Sigma Pi Agnes Fay Morgan Research Award
* 2008 Purdue College of Science Outstanding Undergraduate Teaching Award by an Assistant Professor
* 2007 ACS-ExxonMobil Solid State Chemistry Faculty Fellowship
* 2006 ACS PROGRESS/Dreyfus Lectureship award, American Chemical Society
* 2006 Alfred P. Sloan Research Fellowship, Alfred P. Sloan Foundation | 0 | Theoretical and Fundamental Chemistry |
The synthesis of ring C also required hydroxygeranyl acetate 2. Subsequent steps were allylic oxidation (SeO, tBuOH, salicylic acid) to aldehyde 13, then carbonyl reduction (NaBH) to alcohol 14, then epoxidation (VO(acac), tBuOH) to 15, then alcohol protection (MPM trichloroacetimidate) to MPM ether 16, then radical cyclisation (titanocene dichloride, manganese, triethylborane, TMSCl, KCO) to alcohol 17, alcohol protection (BOMCl, DIPEA) to benzyloxymethyl ether 18, acetate hydrolysis (NaOH) and Ley oxidation to aldehyde 19. | 0 | Theoretical and Fundamental Chemistry |
Berend (Bert) Poolman is a Dutch biochemist, as specialist in bioenergetics of microorganisms and membrane transport. He is a professor of Biochemistry at the University of Groningen and an elected member of the Royal Netherlands Academy of Arts and Sciences (KNAW) since 2009. Poolman is a pioneer in the field of bottom-up synthetic biology, that is, the construction from molecular building blocks of functional metabolic networks and autonomously operating functional systems, which are typical of living cells. Poolman is a lecturer in membrane biology and synthetic biology. | 0 | Theoretical and Fundamental Chemistry |
Gunpowder bombs had been mentioned since the 11th century. In 1000 AD, a soldier by the name of Tang Fu (唐福) demonstrated a design of gunpowder pots (a proto-bomb which spews fire) and gunpowder caltrops, for which he was richly rewarded. In the same year, Xu Dong wrote that trebuchets used bombs that were like "flying fire", suggesting that they were incendiaries. In the military text Wujing Zongyao of 1044, bombs such as the "ten-thousand fire flying sand magic bomb", "burning heaven fierce fire unstoppable bomb", and "thunderclap bomb" (pilipao) were mentioned. However detailed accounts of their use did not appear until the 12th century.
The Jurchen people of Manchuria united under Wanyan Aguda and established the Jin dynasty in 1115. Allying with the Song, they rose rapidly to the forefront of East Asian powers and defeated the Liao dynasty in a shockingly short span of time, destroying the 150-year balance of power between the Song, Liao, and Western Xia. Remnants of the Liao fled to the west and became known as the Qara Khitai, or Western Liao to the Chinese. In the east, the fragile Song-Jin alliance dissolved once the Jin saw how badly the Song army had performed against Liao forces. Realizing the weakness of Song, the Jin grew tired of waiting and captured all five of the Liao capitals themselves. They proceeded to make war on Song, initiating the Jin-Song Wars.
For the first time, two major powers would have access to equally formidable gunpowder weapons. Initially the Jin expected their campaign in the south to proceed smoothly given how poorly the Song had fared against the Liao. However they were met with stout resistance upon besieging Kaifeng in 1126 and faced the usual array of gunpowder arrows and fire bombs, but also a weapon called the "thunderclap bomb" (霹靂炮), which one witness wrote, "At night the thunderclap bombs were used, hitting the lines of the enemy well, and throwing them into great confusion. Many fled, screaming in fright." The thunderclap bomb was previously mentioned in the Wujing Zongyao, but this was the first recorded instance of its use. Its description in the text reads thus:
Jin troops withdrew with a ransom of Song silk and treasure but returned several months later with their own gunpowder bombs manufactured by captured Song artisans. According to historian Wang Zhaochun, the account of this battle provided the "earliest truly detailed descriptions of the use of gunpowder weapons in warfare." Records show that the Jin used gunpowder arrows and trebuchets to hurl gunpowder bombs while the Song responded with gunpowder arrows, fire bombs, thunderclap bombs, and a new addition called the "molten metal bomb" (金汁炮). As the Jin account describes, when they attacked the city's Xuanhua Gate, their "fire bombs fell like rain, and their arrows were so numerous as to be uncountable." The Jin captured Kaifeng despite the appearance of the molten metal bomb and secured another 20,000 fire arrows for their arsenal.
The molten metal bomb appeared again in 1129 when Song general Li Yanxian (李彥仙) clashed with Jin forces while defending a strategic pass. The Jin assault lasted day and night without respite, using siege carts, fire carts, and sky bridges, but each assault was met with Song soldiers who "resisted at each occasion, and also used molten metal bombs. Wherever the gunpowder touched, everything would disintegrate without a trace." | 1 | Applied and Interdisciplinary Chemistry |
GPR126 is necessary for Schwann cell myelination. Knockouts of this adhesion GPCR in both Danio rerio and Mus musculus result in an arrest at the promyelinating stage. Schwann cells arise from the neural crest, which migrates to peripheral nerves to form either myelinating or non-myelinating cells. In GPR126 knockouts, these precursor cells develop to the promyelinating stage, where they have wrapped approximately 1.5 times. Myelination is arrested at the promyelinating stage and in fish no myelin basic protein can be detected. In fish this can be rescued by adding forskolin during development, which rescues myelin basic protein expression. | 1 | Applied and Interdisciplinary Chemistry |
Feline leukemia virus and Feline immunodeficiency virus infections are treated with biologics, including the only immunomodulator currently licensed for sale in the United States, Lymphocyte T-Cell Immune Modulator (LTCI). | 1 | Applied and Interdisciplinary Chemistry |
The trihexagonal tiling has Schläfli symbol of r{6,3}, or Coxeter diagram, , symbolizing the fact that it is a rectified hexagonal tiling, {6,3}. Its symmetries can be described by the wallpaper group p6mm, (*632), and the tiling can be derived as a Wythoff construction within the reflectional fundamental domains of this group. The trihexagonal tiling is a quasiregular tiling, alternating two types of polygons, with vertex configuration (3.6). It is also a uniform tiling, one of eight derived from the regular hexagonal tiling. | 0 | Theoretical and Fundamental Chemistry |
This technique has found applications in many different fields, from semiconductor physics to microelectronics and biology, from basic research to industrial applications. Ellipsometry is a very sensitive measurement technique and provides unequaled capabilities for thin film metrology. As an optical technique, spectroscopic ellipsometry is non-destructive and contactless. Because the incident radiation can be focused, small sample sizes can be imaged and desired characteristics can be mapped over a larger area (m). | 0 | Theoretical and Fundamental Chemistry |
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