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According to researchers, preliminary tests with the simulator, under possible conditions of the early Earth, created protocells: organized collections of lipds which may act as precursors to living cells. According to biologist David Deamer, the device is a game changer, and the cells produced so far are "significant". The "cells are not alive, but are evolutionary steps toward a living system of molecules ... [the simulator] opens up a lot of experimental activities that were literally impossible before.” Based on initial tests with the new simulator technology, project director Rheinstadter stated that it "seems that the formation of life is probably a relatively frequent process in the universe". | 0 | Theoretical and Fundamental Chemistry |
Peripheral blood samples were obtained and processed to isolate plasma following standard protocols. Upon centrifugation, plasma specimens were preserved at −80 °C, awaiting the extraction of ctDNA. The extraction of cfDNA from plasma volumes ranging from 2 to 16 ml was carried out using established laboratory procedures. Following isolation, the concentration of cfDNA was determined using fluorescence-based quantification methods. | 1 | Applied and Interdisciplinary Chemistry |
The minerals found in seawater can also play an important role in the ocean and its ecosystems food cycle. For example, the Southern Ocean contributes greatly to the environmental carbon cycle. Given that this body of water does not contain high levels of iron, the deficiency impacts the marine life living in its waters. As a result, this ocean is not able to produce as much phytoplankton which hinders the first source of the marine food chain. One of the main types of phytoplankton are diatoms which is the primary food source of Antarctic krill. As the cycle continues, various larger sea animals feed off of Antarctic krill, but since there is a shortage of iron from the initial phytoplankton/diatoms, then these larger species also lack iron. The larger sea animals include Baleen Whales such as the Blue Whale and Fin Whale. These whales not only rely on iron for a balance of minerals within their diet, but it also impacts the amount of iron that is regenerated back into the ocean. The whales excretions also contain the absorbed iron which would allow iron to be reinserted into the ocean’s ecosystem. Overall, one mineral deficiency such as iron in the Southern Ocean can spark a significant chain of disturbances within the marine ecosystems which demonstrates the important role that seawater plays in the food chain.
Upon further analysis of the dynamic relationship between diatoms, krill, and baleen whales, fecal samples of baleen whales were examined in Antarctic seawater. The findings included that iron concentrations were 10 million times higher than those found in Antarctic seawater, and krill was found consistently throughout their feces which is an indicator that krill is in whale diets. Antarctic krill had an average iron level of 174.3mg/kg dry weight, but the iron in the krill varied from 12 to 174 mg/kg dry weight. The average iron concentration of the muscular tissue of blue whales and fin whales was 173 mg/kg dry weight, which demonstrates that the large marine mammals are important to marine ecosystems such as they are to the Southern Ocean. In fact, to have more whales in the ocean could heighten the amount of iron in seawater through their excretions which would promote a better ecosystem.
Krill and baleen whales act as large iron reservoirs in seawater in the Southern Ocean. Krill can retain up to 24% of iron found on surface waters within its range.The process of krill feeding on diatoms releases iron into seawater, highlighting them as an important part of the ocean's iron cycle. The advantageous relationship between krill and baleen whales increases the amount of iron that can be recycled and stored in seawater. A positive feedback loop is created, increasing the overall productivity of marine life in the Southern Ocean.
Organisms of all sizes play a significant role in the balance of marine ecosystems with both the largest and smallest inhabitants contributing equally to recycling nutrients in seawater. Prioritizing the recovery of whale populations because they boost the overall productivity in marine ecosystems as well as increasing iron levels in seawater would allow for a balanced and productive system for the ocean. However, a more in depth study is required to understand the benefits of whale feces as a fertilizer and to provide further insight in iron recycling in the Southern Ocean. Projects on the management of ecosystems and conservation are vital for advancing knowledge of marine ecology. | 0 | Theoretical and Fundamental Chemistry |
In physics, the super Tonks–Girardeau gas represents an excited quantum gas phase with strong attractive interactions in a one-dimensional spatial geometry.
Usually, strongly attractive quantum gases are expected to form dense particle clusters and lose all gas-like properties. But in 2005, it was proposed by Stefano Giorgini and co-workers that there is a many-body state of attractively interacting bosons that does not decay in one-dimensional systems. If prepared in a special way, this lowest gas-like state should be stable and show new quantum mechanical properties.
Particles in a super-Tonks gas should be strongly correlated and show long range order with a Luttinger liquid parameter K<1. Since each particle occupies a certain volume, the gas properties are similar to a classical gas of hard rods. Despite the mutual attraction, the single particle wave functions separate and the bosons behave similar to fermions with repulsive, long-range interaction.
To prepare the super-Tonks–Girardeau phase it is necessary to increase the repulsive interaction strength all the way through the Tonks–Girardeau regime up to infinity. Sudden switching from infinitely strong repulsive to infinitely attractive interactions stabilizes the gas against collapse and connects the ground state of the Tonks gas to the excited state of the super-Tonks gas. | 0 | Theoretical and Fundamental Chemistry |
An experiment on oat plants by scientist Maria Quiles, revealed that extreme light intensity can inhibit photosynthesis and result in the lack of PS II activity. This reduction leads to an increase in NAD(P)H and PTOX levels which then causes the stimulation of chlororespiration.
Oat leaves were incubated and Chlorophyll fluorescence emission was used to examine the effect of extreme light intensity. As the emission of the Chlorophyll fluorescence increased the PQ pool decreased. This stimulated the cyclic electron flow, causing NAD(P)H and PTOX levels to ultimately incline and initiate the process of chlororespiration within the thylakoid membrane of oat plants.
The effect of adding n-propyl gallate to the incubated leaves was also observed. N-propyl gallate is a molecule that helps distinguish between PQ reduction and oxidation activities by inhibiting PTOX. Quiles noted an increase in chlorophyll fluorescence inside the thylakoid membrane of plant cells, after the addition of n-propyl gallate. The result led to the stimulation of the NAD(P)H enzyme and its cyclic pathway; causing a continuous increase in chlorophyll fluorescence levels within the oat. | 1 | Applied and Interdisciplinary Chemistry |
Recombination hotspots are DNA sequences that increase local recombination. The HOT1 sequence in yeast is one of the most well studied mitotic recombination hotspots. The HOT1 sequence includes an RNA polymerase I transcription promoter. In a yeast mutant strain defective in RNA polymerase I the HOT1 activity in promoting recombination is abolished. The level of RNA polymerase I transcription activity that is dependent on the promoter in the HOT1 sequence appears to determine the level of nearby mitotic recombination. | 1 | Applied and Interdisciplinary Chemistry |
A ninhydrin solution is commonly used by forensic investigators in the analysis of latent fingerprints on porous surfaces such as paper. The amino acids present in the minute sweat secretions that gather on the finger's unique ridges transfer to surfaces that are touched. Exposure of the surface to ninhydrin converts the amino acids into visibly colored products and thus reveals the print. The test solutions suffer from poor long-term stability, especially if not kept cold.
To further enhance the ability of ninhydrin, a solution of 1,2-indandione and zinc chloride (IND-Zn) can be used prior to ninhydrin. This sequence leads to greater overall reaction of the amino acids, possibly by IND-Zn helping to release them from the surface for the subsequent ninhydrin reaction. | 0 | Theoretical and Fundamental Chemistry |
Ballistic foam is a foam that sets hard. It is widely used in the manufacture and repair of aircraft to form a light but strong filler for aircraft wings. The foam is used to surround aircraft fuel tanks to reduce the chance of fires caused by the penetration of incendiary projectiles.
Ballistic foam is a type of polyurethane foam placed in the dry bays of aircraft. Ballistic foam prevents fires, adds strength to the structure, slows down the speed of shrapnel during attacks, and offers cost-effective protection.
Ballistic foam is placed in the dry bays to provide a barrier between the spark and the fuel. As bullets or shrapnel penetrate the mold line skin surrounding the outermost portions of the dry bay, the ballistic foam deprives sparks of oxygen. Thus when the article punctures the fuel tank, a fire is not started. Not only does the foam displace oxygen, but all gases, including explosive vapors which could magnify the destructive effects of ballistic attack. Dry bays, voids, may also contain “onboard ignition sources” like hot surfaces and electrical sparks which benefit both from a lack of gases and the fire-retardant nature of the foam.
Ballistic foam strengthens aircraft by protecting it from fire as well as fluid while adding very little weight. The protection from fluid involves resisting damage by “moisture, hydrocarbon fuels, hydraulic fluids, and most common solvents”. The density of the foam varies with the type being used; Type 2.5 is a white to light amber foam weighing 2.5 pounds per cubic foot, while Type 1.8 is a pale blue to green foam weighing 1.8 pounds per cubic foot.
Chopped fiberglass strands embedded in the foam add to the structural integrity through physical support and shrapnel mitigation. The layer that strengthens the foam in turn strengthens the airframe. The layer of fiberglass also prevents shrapnel and bullets from rupturing the foam. The fiber glass then allows the damage caused by projectile penetration to heal more effectively.
The passive protection afforded by ballistic foam is very simple and inexpensive compared to active protection. One method of active protection is done by filling large dry bays with inert gases which will not sustain a flame. This process is very expensive and complex. Active protection only offers a “one time” chance for ballistic protection while the ballistic foam is always available. | 0 | Theoretical and Fundamental Chemistry |
Corrosion of cast-iron-pipe can occur on both the internal and external surfaces. In electro-chemical corrosion, internal anodes develop where bare iron is exposed to aggressive waters, promoting iron to move into solution. The iron combines with various components in the water, forming a tubercle on the pipe interior. This process of tuberculation can eventually cause significant restrictions in cross-sectional area within the pipe. Since the tubercles are irregularly shaped, buildup of bacterial growths on the surface are likely. As more iron moves into solution, the result is a loss of pipe structure over time potentially affecting pipe integrity. In storm and sanitary sewer systems, the creation of acidic gases (such as hydrogen sulfide) by microbial action can further corrode internal pipe walls but is most pronounced on the inside ‘ceiling’ of the pipe.
Starting in 1922, internal cement linings were introduced to act as a barrier to minimize internal corrosion. In 1929, the American Standard Association (ASA) Sectional Committee issued a tentative standard for cement-mortar linings, which was published in 1932. In 1939, American Standard A21.4 was published, which defined a Type I cement coating on the inside of waterline pipe to be used. When the standard was updated in 1953, the Type I cement was replaced with Type II, since it was believed that Type II was a more closely controlled product. The standard was further revised in 1964, which included the use of either Type I or Type II cement, and making two different mortar thicknesses available. | 1 | Applied and Interdisciplinary Chemistry |
Fluid inclusions can provide useful data in mineral exploration, as their characteristics depend on the mineralization process. The methods of using fluid inclusions to identify mineral deposits include assessing the abundance of a specific inclusion type, looking into variations in the inclusions' temperatures of phase changes during heating and cooling, and variations in other properties such as decrepitation behavior, and inclusions chemistry. Observation and point-counting of thin-sections of samples is used to identify the occurrence of specific inclusion types. If an abundance of similar fluid inclusions are found in close geographic proximity, one can conclude that the surrounding rock types are similar if not the same. Microthermometric properties (changes in temperature during phase changes) are used to characterize and categorize areas that witnessed thermal activity during mineral formation.
Fluid inclusions have been used to identify deposits of oil and gas. Drilling cuts, cores, and/or outcrop materials are preserved for their pore-fluids, and the chemistry of the fluid is analyzed with Fluid Inclusion Stratigraphy (FIS). FIS analysis takes the spectrometric reading of a fluid inclusion's volatile species; these are indicative of a natural gas or oil deposit nearby. The abundance of similar fluid inclusions could, however, be attributed to hydrocarbon migration and accumulation, so other techniques are used to confirm the presence of the oil deposit after initial detection of fluid inclusions. | 0 | Theoretical and Fundamental Chemistry |
Pauline Rudd is a British biochemist and Professor at the Microbiome Institute, University College Cork. She is a founder of Wessex Biochemicals, a Fellow of the Royal Society of Medicine and was awarded the James Gregory Medal in 2010. | 1 | Applied and Interdisciplinary Chemistry |
*Group 2 elements form [[Alkaline earth octacarbonyl complex|[M(CO)]]] (M = Ca, Sr, Ba), characterized in gas phase by mass spectrometry and vibrational spectroscopy.
*Group 3 elements form [Sc(CO)] and [Y(CO)] in gas phase.
*Group 7 elements as monocations resemble neutral group 6 derivative [M(CO)] (M = Mn, Tc, Re).
*Group 8 elements as dications also resemble neutral group 6 derivatives [M(CO)] (M = Fe, Ru, Os). | 0 | Theoretical and Fundamental Chemistry |
The furnace comprises three distinct zones:
* Firstly, the preheating zone heats the ore to 800 °C using the hot fumes within the furnace. Ore reduction occurs only if temperatures exceed 900-1,000 °C, while the coal releases its most volatile constituents.
* Secondly, the reduction zone is situated in the middle of the furnace, where coal and iron oxides combine to produce carbon monoxide. The carbon monoxide is released from the charge, generating a gaseous layer that shields the charge against the oxidizing air circulating above. As a consequence, this excessive gas is combusted, raising the temperature of the furnace walls, which then transfer the heat back to the charge due to rotary motion. The temperature eventually increases to 800 – 1,200 °C. Subsequently, the iron oxides are gradually altered into ferronickel or metallic iron. The metal produced is in the form of metallic sponge particles that are finely dispersed in the powdery gangue.
* Reduction is complete by the end of the furnace, and there is a minimal amount of CO produced. This is due to the fact that the charge is no longer protected from oxidation by the air blown in at the base of the furnace. As a result, a violent but shallow reoxidation of the iron occurs. Some of the oxidized iron is returned to the core of the charge by rotation where it is further reduced with residual coal. The remaining material mixes with waste to create a thick slag that cannot blend with the produced metal. This extremely hot reaction melts the non-oxidized iron and nickel, which clump together forming nodules named Luppen.
Control of temperature is critical in regards to the ores physicochemical characteristics. Overly high temperatures or unsuitable granulometry lead to the creation of rings of sintered material that accumulate on the walls of the furnace. Typically, a ring of iron-poor slag, known as slag, is formed at two-thirds of the distance along the furnace. Similarly, a metal ring usually forms around ten meters from the outlet. These rings disturb the flow of materials and gas, diminishing the furnaces useful capacity, sometimes completely obstructing it. The process's revival is hindered by the formation of a ring, particularly in China. In the early 21st century, industrialists abandoned its adoption after recognizing how critical and challenging managing this parameter was.
While slag melting consumes energy, it enables us to govern the charges behavior in the furnace. Additionally, we need a minimum of 800 to 1,000 kg of slag per ton of iron to prevent Luppen from growing too big. Slag limits coal segregation as coal is much less dense than ore and would float to the surface of the mixture. It transforms into a paste that guards the metal against oxidation when heated and simplifies both Luppen' processing and furnace cleaning during maintenance shutdowns through vitrification when it gets cold. | 1 | Applied and Interdisciplinary Chemistry |
* BS 1881:204 Testing concrete. Recommendations on the use of electromagnetic covermeters
* DGZfP:B2: Guideline “für Bewehrungsnachweis und Überdeckungsmessung bei Stahl- und Spannbeton”
* DIN 1045: Guideline Concrete, reinforced and prestressed concrete structures
* ACI Concrete Practices Non Destructive testing 228.2R-2.51: Covermeters | 1 | Applied and Interdisciplinary Chemistry |
The principal methods of this are enamelled glass, essentially a technique for painting patterns or images, used for both glass vessels and on stained glass, and glass paint, typically in black, and silver stain, giving yellows to oranges on stained glass. All of these are fired in a kiln or furnace to fix them, and can be extremely durable when properly applied. This is not true of "cold-painted" glass, using oil paint or other mixtures, which rarely last more than a few centuries. | 0 | Theoretical and Fundamental Chemistry |
Lithium was first used in the 19th century as a treatment for gout after scientists discovered that, at least in the laboratory, lithium could dissolve uric acid crystals isolated from the kidneys. The levels of lithium needed to dissolve urate in the body, however, were toxic. Because of prevalent theories linking excess uric acid to a range of disorders, including depressive and manic disorders, Carl Lange in Denmark and William Alexander Hammond in New York City used lithium to treat mania from the 1870s onwards.
By the turn of the 20th century, as theory regarding mood disorders evolved and so-called "brain gout" disappeared as a medical entity, the use of lithium in psychiatry was largely abandoned; however, a number of lithium preparations were still produced for the control of renal calculi and uric acid diathesis. As accumulating knowledge indicated a role for excess sodium intake in hypertension and heart disease, lithium salts were prescribed to patients for use as a replacement for dietary table salt (sodium chloride). This practice and the sale of lithium itself were both banned in the United States in February 1949, following publication of reports detailing side effects and deaths.
Also in 1949, the Australian psychiatrist John Cade and Australian biochemist Shirley Andrews rediscovered the usefulness of lithium salts in treating mania while working at the Royal Park Psychiatric Hospital in Victoria. They were injecting rodents with urine extracts taken from manic patients in an attempt to isolate a metabolic compound which might be causing mental symptoms. Since uric acid in gout was known to be psychoactive, (adenosine receptors on neurons are stimulated by it; caffeine blocks them), they needed soluble urate for a control. They used lithium urate, already known to be the most soluble urate compound, and observed that it caused the rodents to become tranquil. Cade and Andrews traced the effect to the lithium ion itself, and after Cade ingested lithium himself to ensure its safety in humans, he proposed lithium salts as tranquilizers. He soon succeeded in controlling mania in chronically hospitalized patients with them. This was one of the first successful applications of a drug to treat mental illness, and it opened the door for the development of medicines for other mental problems in the next decades.
The rest of the world was slow to adopt this treatment, largely because of deaths which resulted from even relatively minor overdosing, including those reported from use of lithium chloride as a substitute for table salt. Largely through the research and other efforts of Denmark's Mogens Schou and Paul Baastrup in Europe, and Samuel Gershon and Baron Shopsin in the U.S., this resistance was slowly overcome. Following the recommendation of the APA Lithium Task Force (William Bunney, Irvin Cohen (Chair), Jonathan Cole, Ronald R. Fieve, Samuel Gershon, Robert Prien, and Joseph Tupin), the application of lithium in manic illness was approved by the United States Food and Drug Administration in 1970, becoming the 50th nation to do so. In 1974, this application was extended to its use as a preventive agent for manic-depressive illness.
Fieve, who had opened the first lithium clinic in North America in 1966, helped popularize the psychiatric use of lithium through his national TV appearances and his bestselling book, Moodswing. In addition, Fieve and David L. Dunner developed the concept of "rapid cycling" bipolar disorder based on non-response to lithium.
Lithium has now become a part of Western popular culture. Characters in Pi, Premonition, Stardust Memories, American Psycho, Garden State, and An Unmarried Woman all take lithium. Its the chief constituent of the calming drug in Ira Levins dystopian This Perfect Day. Sirius XM Satellite Radio in North America has a 1990s alternative rock station called Lithium, and several songs refer to the use of lithium as a mood stabilizer. These include: "Equilibrium met Lithium" by South African artist Koos Kombuis, "Lithium" by Evanescence, "Lithium" by Nirvana, "Lithium and a Lover" by Sirenia, "Lithium Sunset", from the album Mercury Falling by Sting, and "Lithium" by Thin White Rope. | 1 | Applied and Interdisciplinary Chemistry |
Hydrogen bonding is of persistent theoretical interest. According to a modern description integrates both the intermolecular O:H lone pair ":" nonbond and the intramolecular polar-covalent bond associated with repulsive coupling.
Quantum chemical calculations of the relevant interresidue potential constants (compliance constants) revealed large differences between individual H bonds of the same type. For example, the central interresidue hydrogen bond between guanine and cytosine is much stronger in comparison to the bond between the adenine-thymine pair.
Theoretically, the bond strength of the hydrogen bonds can be assessed using NCI index, non-covalent interactions index, which allows a visualization of these non-covalent interactions, as its name indicates, using the electron density of the system.
Interpretations of the anisotropies in the Compton profile of ordinary ice claim that the hydrogen bond is partly covalent. However, this interpretation was challenged.
Most generally, the hydrogen bond can be viewed as a metric-dependent electrostatic scalar field between two or more intermolecular bonds. This is slightly different from the intramolecular bound states of, for example, covalent or ionic bonds. However, hydrogen bonding is generally still a bound state phenomenon, since the interaction energy has a net negative sum. The initial theory of hydrogen bonding proposed by Linus Pauling suggested that the hydrogen bonds had a partial covalent nature. This interpretation remained controversial until NMR techniques demonstrated information transfer between hydrogen-bonded nuclei, a feat that would only be possible if the hydrogen bond contained some covalent character. | 0 | Theoretical and Fundamental Chemistry |
Metallurgists study the microscopic and macroscopic structure of metals using metallography, a technique invented by Henry Clifton Sorby.
In metallography, an alloy of interest is ground flat and polished to a mirror finish. The sample can then be etched to reveal the microstructure and macrostructure of the metal. The sample is then examined in an optical or electron microscope, and the image contrast provides details on the composition, mechanical properties, and processing history.
Crystallography, often using diffraction of x-rays or electrons, is another valuable tool available to the modern metallurgist. Crystallography allows identification of unknown materials and reveals the crystal structure of the sample. Quantitative crystallography can be used to calculate the amount of phases present as well as the degree of strain to which a sample has been subjected. | 1 | Applied and Interdisciplinary Chemistry |
The external stimulus (i.e., the drug or ligand) physically binds to ("hits") the biological target. The interaction between the substance and the target may be:
* noncovalent – A relatively weak interaction between the stimulus and the target where no chemical bond is formed between the two interacting partners and hence the interaction is completely reversible.
* reversible covalent – A chemical reaction occurs between the stimulus and target in which the stimulus becomes chemically bonded to the target, but the reverse reaction also readily occurs in which the bond can be broken.
* irreversible covalent – The stimulus is permanently bound to the target through irreversible chemical bond formation.
Depending on the nature of the stimulus, the following can occur:
* There is no direct change in the biological target, but the binding of the substance prevents other endogenous substances (such as activating hormones) from binding to the target. Depending on the nature of the target, this effect is referred as receptor antagonism, enzyme inhibition, or ion channel blockade.
* A conformational change in the target is induced by the stimulus which results in a change in target function. This change in function can mimic the effect of the endogenous substance in which case the effect is referred to as receptor agonism (or channel or enzyme activation) or be the opposite of the endogenous substance which in the case of receptors is referred to as inverse agonism. | 1 | Applied and Interdisciplinary Chemistry |
Preoperative administration of Lugols solution decreases intraoperative blood loss during thyroidectomy in patients with Graves disease. However, it appears ineffective in patients who are already euthyroid on anti-thyroid drugs and levothyroxine.
* During colposcopy, Lugols iodine is applied to the vagina and cervix. Normal vaginal tissue stains brown due to its high glycogen content, while tissue suspicious for cancer does not stain, and thus appears pale compared to the surrounding tissue. Biopsy of suspicious tissue can then be performed. This is called a Schillers test.
* Patients at high risk of oesophageal squamous cell carcinoma are usually followed using a combination of Lugol’s chromoendoscopy and narrow-band imaging. With Lugol’s iodine, low-grade dysplasia appears as an unstained or weakly stained area; high-grade dysplasia is consistently unstained.
* Lugol's iodine may also be used to better visualize the mucogingival junction in the mouth. Similar to the method of staining mentioned above regarding a colposcopy, alveolar mucosa has a high glycogen content that gives a positive iodine reaction vs. the keratinized gingiva.
* Lugol's iodine may also be used as an oxidizing germicide, however it is somewhat undesirable in that it may lead to scarring and discolors the skin temporarily. One way to avoid this problem is by using a solution of 70% ethanol to wash off the iodine later.
* Lugols iodine was distributed in Polish Peoples Republic after the Chernobyl catastrophe, due to government not being informed of how severe the event was and overestimating radiation, and unavailability of iodine tablets. | 0 | Theoretical and Fundamental Chemistry |
Because of the multiple carbon–fluorine bonds, and the high electronegativity of fluorine, the carbon in tetrafluoromethane has a significant positive partial charge which strengthens and shortens the four carbon–fluorine bonds by providing additional ionic character. Carbon–fluorine bonds are the strongest single bonds in organic chemistry. Additionally, they strengthen as more carbon–fluorine bonds are added to the same carbon. In the one carbon organofluorine compounds represented by molecules of fluoromethane, difluoromethane, trifluoromethane, and tetrafluoromethane, the carbon–fluorine bonds are strongest in tetrafluoromethane. This effect is due to the increased coulombic attractions between the fluorine atoms and the carbon because the carbon has a positive partial charge of 0.76. | 1 | Applied and Interdisciplinary Chemistry |
The branched and cyclic nature of carbohydrates poses particular problems to structure validation tools. At higher resolutions, it is possible to determine the sequence/structure of oligo- and poly-saccharides, both as covalent modifications and as ligands. However, at lower resolutions (typically lower than 2.0Å), sequences/structures should either match known structures, or be supported by complementary techniques such as Mass Spectrometry. Also, monosaccharides have clear conformational preferences (saturated rings are typically found in chair conformations), but errors introduced during model building and/or refinement (wrong linkage chirality or distance, or wrong choice of model - see for recommendations on carbohydrate model building and refinement and for reviews on general errors in carbohydrate structures) can bring their atomic models out of the more likely low-energy state. Around 20% of the deposited carbohydrate structures are in a higher-energy conformation not justified by the structural data (measured using real-space correlation coefficient).
A number of carbohydrate validation web services are available at [http://ww.glycosciences.de glycosciences.de] (including nomenclature checks and linkage checks by [http://www.glycosciences.de/tools/pdb-care/ pdb-care], and cross-validation with Mass Spectrometry data through the use of GlycanBuilder), whereas the CCP4 suite currently distributes [http://www.ccp4.ac.uk/html/privateer.html Privateer], which is a tool that is integrated into the model building and refinement process itself. Privateer is able to check stereo- and regio-chemistry, ring conformation and puckering, linkage torsions, and real-space correlation against positive omit density, generating aperiodic torsion restraints on ring bonds, which can be used by any refinement software in order to maintain the monosaccharide's minimal energy conformation.
Privateer also generates scalable two-dimensional SVG diagrams according to the Essentials of Glycobiology standard symbol nomenclature containing all the validation information as tooltip annotations (see figure). This functionality is currently integrated into other CCP4 programs, such as the molecular graphics program CCP4mg (through the Glycoblocks 3D representation, which conforms to the standard symbol nomenclature) and the suite's graphical interface, CCP4i2. | 1 | Applied and Interdisciplinary Chemistry |
Thermochemical equations can be changed, as mentioned above, by multiplying by any numerical coefficient. All agents must be multiplied, including ΔH. Using the thermochemical equation of variables as above, one gets the following example.
:A + B → C
:ΔH= (±) #
One must assume that A needs to be multiplied by two in order for the thermochemical equation to be used. All the agents in the reaction must then be multiplied by the same coefficient, like so:
:2A + 2B → 2C
:2ΔH= 2[(±) #]
This is again considered to be logical when the First Law of Thermodynamics is considered. Twice as much product is produced, so twice as much heat is removed or given off. The division of coefficients functions in the same way. | 0 | Theoretical and Fundamental Chemistry |
Another form of dimensional analysis that will result in the Grashof number is known as the Buckingham π theorem. This method takes into account the buoyancy force per unit volume, due to the density difference in the boundary layer and the bulk fluid.
This equation can be manipulated to give,
The list of variables that are used in the Buckingham π method is listed below, along with their symbols and dimensions.
With reference to the Buckingham π theorem there are dimensionless groups. Choose , , and as the reference variables. Thus the groups are as follows:
Solving these groups gives:
From the two groups and the product forms the Grashof number:
Taking and the preceding equation can be rendered as the same result from deriving the Grashof number from the energy equation.
In forced convection the Reynolds number governs the fluid flow. But, in natural convection the Grashof number is the dimensionless parameter that governs the fluid flow. Using the energy equation and the buoyant force combined with dimensional analysis provides two different ways to derive the Grashof number. | 1 | Applied and Interdisciplinary Chemistry |
Plakophilin are proteins of the cytoskeleton. They are involved in regulating the adhesive activity of cadherin.
The three types of plakophilin proteins found in humans are PKP1, PKP2, and PKP3; all exhibiting dual localization in the nucleus as well as desmosomes.
Genes include:
* PKP1
* PKP2
* PKP3 | 1 | Applied and Interdisciplinary Chemistry |
In marine systems DOC originates from either autochthonous or allochthonous sources. Autochthonous DOC is produced within the system, primarily by plankton organisms and in coastal waters additionally by benthic microalgae, benthic fluxes, and macrophytes, whereas allochthonous DOC is mainly of terrestrial origin supplemented by groundwater and atmospheric inputs. In addition to soil derived humic substances, terrestrial DOC also includes material leached from plants exported during rain events, emissions of plant materials to the atmosphere and deposition in aquatic environments (e.g., volatile organic carbon and pollens), and also thousands of synthetic human-made organic chemicals that can be measured in the ocean at trace concentrations.
Dissolved organic carbon (DOC) represents one of the Earth's major carbon pools. It contains a similar amount of carbon as the atmosphere and exceeds the amount of carbon bound in marine biomass by more than two-hundred times. DOC is mainly produced in the near-surface layers during primary production and zooplankton grazing processes. Other sources of marine DOC are dissolution from particles, terrestrial and hydrothermal vent input, and microbial production. Prokaryotes (bacteria and archaea) contribute to the DOC pool via release of capsular material, exopolymers, and hydrolytic enzymes, as well as via mortality (e.g. viral shunt). Prokaryotes are also the main decomposers of DOC, although for some of the most recalcitrant forms of DOC very slow abiotic degradation in hydrothermal systems or possibly sorption to sinking particles may be the main removal mechanism. Mechanistic knowledge about DOC-microbe-interactions is crucial to understand the cycling and distribution of this active carbon reservoir. | 1 | Applied and Interdisciplinary Chemistry |
In eukaryotes, NADH is the most important electron donor. The associated electron transport chain is NADH → Complex I → Q → Complex III → cytochrome c → Complex IV → O where Complexes I, III and IV are proton pumps, while Q and cytochrome c are mobile electron carriers. The electron acceptor for this process is molecular oxygen.
In prokaryotes (bacteria and archaea) the situation is more complicated, because there are several different electron donors and several different electron acceptors. The generalized electron transport chain in bacteria is:
Donor Donor Donor
dehydrogenase → quinone → bc → cytochrome
oxidase(reductase) oxidase(reductase)
Acceptor Acceptor
Electrons can enter the chain at three levels: at the level of a dehydrogenase, at the level of the quinone pool, or at the level of a mobile cytochrome electron carrier. These levels correspond to successively more positive redox potentials, or to successively decreased potential differences relative to the terminal electron acceptor. In other words, they correspond to successively smaller Gibbs free energy changes for the overall redox reaction.
Individual bacteria use multiple electron transport chains, often simultaneously. Bacteria can use a number of different electron donors, a number of different dehydrogenases, a number of different oxidases and reductases, and a number of different electron acceptors. For example, E. coli (when growing aerobically using glucose and oxygen as an energy source) uses two different NADH dehydrogenases and two different quinol oxidases, for a total of four different electron transport chains operating simultaneously.
A common feature of all electron transport chains is the presence of a proton pump to create an electrochemical gradient over a membrane. Bacterial electron transport chains may contain as many as three proton pumps, like mitochondria, or they may contain two or at least one. | 1 | Applied and Interdisciplinary Chemistry |
The surface of photocathodes can be characterized by various surface sensitive techniques like scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy. | 0 | Theoretical and Fundamental Chemistry |
The development of the nonapeptide teprotide (Glu-Trp-Pro-Arg-Pro-Gln-Ile-Pro-Pro), which was originally isolated from the venom of the Brazilian pit viper Bothrops jararaca, greatly clarified the importance of ACE in hypertension. However, its lack of oral activity limited its therapeutic utility.
L-benzylsuccinic acid (2(R)-benzyl-3-carboxypropionic acid) was described to be the most potent inhibitor of carboxypeptidase A in the early 1980s. The authors referred to it as a by-product analog and it was proposed to bind to the active site of carboxypeptidase A via succinyl carboxyl group and a carbonyl group. Their findings established that L-benzylsuccinic acid is bound at a single locus at the active site of carboxypeptidase A. The authors discussed but dismissed the suggestion that the carboxylate function might bind to the catalytically functional zinc ion present at the active site. Later however this was found to be the case. | 1 | Applied and Interdisciplinary Chemistry |
Radon harms indoor air quality in many homes. (See "Radon in Houses" below.)
Radon (Rn) released into the air decays to Pb and other radioisotopes and the levels of Pb can be measured. It is important to note that the rate of deposition of this radioisotope is very dependent on the season. Here is a graph of the deposition rate observed in Japan. | 0 | Theoretical and Fundamental Chemistry |
* Achille Le Bel Grand Prize of the French Chemical Society (1979)
* Pierre Desnuelle Prize from the French Academy of sciences (1996)
* Medal of the Berthelot Foundation (1996)
* Claude S. Hudson Award in Carbohydrate Chemistry from the American Chemical Society (2007)
* Elected Correspondent of the French Academy of sciences (1996)
* Honorary doctorate from the University of Lisbon (2005)
* Elected member of the French Academy of sciences (2003)
* Haworth Memorial Reading and Haworth Medal from the Royal Society of Chemistry (Great Britain, 2011).
* Associate Member of the National Academy of Pharmacy (2016).
* Chevalier of the Légion d'honneur and Commandeur of the Palmes Académiques. | 0 | Theoretical and Fundamental Chemistry |
Acoustic Doppler velocimetry (ADV) is designed to record instantaneous velocity components at a single point with a relatively high frequency. Measurements are performed by measuring the velocity of particles in a remote sampling volume based upon the Doppler shift effect. | 1 | Applied and Interdisciplinary Chemistry |
The BioBricks assembly standard was described and introduced by Tom Knight in 2003 and it has been constantly updated since then. Currently, the most commonly used BioBricks standard is the assembly standard 10, or BBF . BioBricks defines the prefix and suffix sequences required for a DNA part to be compatible with the BioBricks assembly method, allowing the joining of all DNA parts which are in the BioBricks format.
The prefix contains the restriction sites for EcoRI, NotI and XBaI, while the suffix contains the SpeI, NotI and PstI restriction sites. Outside of the prefix and suffix regions, the DNA part must not contain these restriction sites. To join two BioBrick parts together, one of the plasmids is digested with EcoRI and SpeI while the second plasmid is digested with EcoRI and XbaI. The two EcoRI overhangs are complementary and will thus anneal together, while SpeI and XbaI also produce complementary overhangs which can also be ligated together. As the resulting plasmid contains the original prefix and suffix sequences, it can be used to join with more BioBricks parts. Because of this property, the BioBricks assembly standard is said to be idempotent in nature. However, there will also be a "scar" sequence (either TACTAG or TACTAGAG) formed between the two fused BioBricks. This prevents BioBricks from being used to create fusion proteins, as the 6bp scar sequence codes for a tyrosine and a stop codon, causing translation to be terminated after the first domain is expressed, while the 8bp scar sequence causes a frameshift, preventing continuous readthrough of the codons. To offer alternative scar sequences that for example give a 6bp scar, or scar sequences that do not contain stop codons, other assembly standards such as the BB-2 Assembly, BglBricks Assembly, Silver Assembly and the Freiburg Assembly were designed.
While the easiest method to assemble BioBrick parts is described above, there also exist several other commonly used assembly methods that offer several advantages over the standard assembly. The 3 antibiotic (3A) assembly allows for the correct assembly to be selected via antibiotic selection, while the amplified insert assembly seeks to overcome the low transformation efficiency seen in 3A assembly.
The BioBrick assembly standard has also served as inspiration for using other types of endonucleases for DNA assembly. For example, both the iBrick standard and the HomeRun vector assembly standards employ homing endonucleases instead of type II restriction enzymes. | 1 | Applied and Interdisciplinary Chemistry |
Stretched film linear dichroism is a method of orientation based on incorporating the sample molecules into a polyethylene film. The polyethylene film is then stretched, causing the randomly oriented molecules on the film to ‘follow’ the movement of the film. The stretching of the film results in the sample molecules being oriented in the direction of the stretch. | 0 | Theoretical and Fundamental Chemistry |
*There are several substances that have antihistaminergic action despite not being ligands for the histamine receptor. For instance, epinephrine raises arterial pressure through vasoconstriction mediated by A1-adrenergic receptor activation, in contrast to histamine, which lowers arterial pressure. Thus, despite not being true antihistamines because they do not bind to and block the histamine receptor, epinephrine and other such substances are physiological antagonists to histamine. | 1 | Applied and Interdisciplinary Chemistry |
In the case of octahedral complexes, the question of high spin vs low spin first arises for d, since it has more than the 3 electrons to fill the non-bonding d orbitals according to ligand field theory or the stabilized d orbitals according to crystal field splitting.
All complexes of second and third row metals are low-spin.
;d:
:Octahedral high-spin: 4 unpaired electrons, paramagnetic, substitutionally labile. Includes Cr (many complexes assigned as Cr(II) are however Cr(III) with reduced ligands), Mn.
:Octahedral low-spin: 2 unpaired electrons, paramagnetic, substitutionally inert. Includes Cr, Mn.
;d:
:Octahedral high-spin: 5 unpaired electrons, paramagnetic, substitutionally labile. Includes Fe, Mn. Example: Tris(acetylacetonato)iron(III).
:Octahedral low-spin: 1 unpaired electron, paramagnetic, substitutionally inert. Includes Fe. Example: [[ferricyanide|[Fe(CN)]]].
;d:
:Octahedral high-spin: 4 unpaired electrons, paramagnetic, substitutionally labile. Includes Fe, Co. Examples: [Fe(HO)], [CoF].
:Octahedral low-spin: no unpaired electrons, diamagnetic, substitutionally inert. Includes Fe, Co, Ni. Example: [[Hexamminecobalt(III) chloride|[Co(NH)]]].
;d:
:Octahedral high-spin: 3 unpaired electrons, paramagnetic, substitutionally labile. Includes Co, Ni.
:Octahedral low-spin:1 unpaired electron, paramagnetic, substitutionally labile. Includes Co, Ni. Example: [Co(NH)].
;d:Octahedral high-spin: 2 unpaired electrons, paramagnetic, substitutionally labile. Includes Ni. Example: [[Hexaamminenickel chloride|[Ni(NH)]]].
:Tetrahedral high-spin: 2 unpaired electrons, paramagnetic, substitutionally labile. Includes Ni. Example: [[Tetrachloronickelate|[NiCl]]].
:Square planar low-spin: no unpaired electrons, diamagnetic, substitutionally inert. Includes Ni. Example: [[Cyanonickelate|[Ni(CN)]]]. | 0 | Theoretical and Fundamental Chemistry |
If the specific rotation, of a pure chiral compound is known, it is possible to use the observed specific rotation, to determine the enantiomeric excess (ee), or "optical purity", of a sample of the compound, by using the formula:
For example, if a sample of bromobutane measured under standard conditions has an observed specific rotation of −9.2°, this indicates that the net effect is due to (9.2°/23.1°)(100%) = 40% of the R enantiomer. The remainder of the sample is a racemic mixture of the enantiomers (30% R and 30% S), which has no net contribution to the observed rotation. The enantiomeric excess is 40%; the total concentration of R is 70%.
However, in practice the utility of this method is limited, as the presence of small amounts of highly rotating impurities can greatly affect the rotation of a given sample. Moreover, the optical rotation of a compound may be non-linearly dependent on its enantiomeric excess because of aggregation in solution. For these reasons other methods of determining the enantiomeric ratio, such as gas chromatography or HPLC with a chiral column, are generally preferred. | 0 | Theoretical and Fundamental Chemistry |
The ICRP recommends a number of limits for dose uptake in table 8 of report 103. These limits are "situational", for planned, emergency and existing situations. Within these situations, limits are given for the following groups:
* Planned exposure – limits given for occupational, medical and public
* Emergency exposure – limits given for occupational and public exposure
* Existing exposure – All persons exposed
For occupational exposure, the limit is 50 mSv in a single year with a maximum of 100 mSv in a consecutive five-year period, and for the public to an average of 1 mSv (0.001 Sv) of effective dose per year, not including medical and occupational exposures.
For comparison, natural radiation levels inside the United States Capitol are such that a human body would receive an additional dose rate of 0.85 mSv/a, close to the regulatory limit, because of the uranium content of the granite structure. According to the conservative ICRP model, someone who spent 20 years inside the capitol building would have an extra one in a thousand chance of getting cancer, over and above any other existing risk (calculated as: 20 a·0.85 mSv/a·0.001 Sv/mSv·5.5%/Sv ≈ 0.1%). However, that "existing risk" is much higher; an average American would have a 10% chance of getting cancer during this same 20-year period, even without any exposure to artificial radiation (see natural Epidemiology of cancer and cancer rates). These estimates are, however, unmindful of every living cell's natural repair mechanisms, evolved over a few billion years of exposure to environmental chemical and radiation threats that were higher in the past, and exaggerated by the evolution of oxygen metabolism. | 0 | Theoretical and Fundamental Chemistry |
Using a volume integral on dimensions, the density of states is:
The Fermi energy is obtained by looking for the number density of particles:
To get:
where is the corresponding d-dimensional volume, is the dimension for the internal Hilbert space. For the case of spin-½, every energy is twice-degenerate, so in this case .
A particular result is obtained for , where the density of states becomes a constant (does not depend on the energy): | 0 | Theoretical and Fundamental Chemistry |
It is thought that erythroid differentiation is primarily dependent on the presence and induction of erythroid transcriptional factors such as GATA-1, FOG-1 and EKLF, as well as the suppression of myeloid/lymphoid transcriptional factors such as PU.1. Direct and significant effects of EpoR signaling specifically upon the induction of erythroid-specific genes such as beta-globin, have been mainly elusive. It is known that GATA-1 can induce EpoR expression. In turn, EpoR's PI3-K/AKT signaling pathway augments GATA-1 activity. | 1 | Applied and Interdisciplinary Chemistry |
For contact potential measurements a lock-in amplifier is used to detect the cantilever oscillation at ω. During the scan V will be adjusted so that the electrostatic forces between the tip and the sample become zero and thus the response at the frequency ω becomes zero. Since the electrostatic force at ω depends on V − V, the value of V that minimizes the ω-term corresponds to the contact potential. Absolute values of the sample work function can be obtained if the tip is first calibrated against a reference sample of known work function. Apart from this, one can use the normal topographic scan methods at the resonance frequency ω independently of the above. Thus, in one scan, the topography and the contact potential of the sample are determined simultaneously.
This can be done in (at least) two different ways: 1) The topography is captured in AC mode which means that the cantilever is driven by a piezo at its resonant frequency. Simultaneously the AC voltage for the KPFM measurement is applied at a frequency slightly lower than the resonant frequency of the cantilever. In this measurement mode the topography and the contact potential difference are captured at the same time and this mode is often called single-pass. 2) One line of the topography is captured either in contact or AC mode and is stored internally. Then, this line is scanned again, while the cantilever remains on a defined distance to the sample without a mechanically driven oscillation but the AC voltage of the KPFM measurement is applied and the contact potential is captured as explained above. It is important to note that the cantilever tip must not be too close to the sample in order to allow good oscillation with applied AC voltage. Therefore, KPFM can be performed simultaneously during AC topography measurements but not during contact topography measurements. | 0 | Theoretical and Fundamental Chemistry |
FSP was used to modify a Mg alloy and insert nano-sized SiO. The test was conducted a total four times with the average grain size varying from 0.5–2μm. This nearly doubled the hardness of the Mg and also increased the super-plasticity. At room temperature, the yield stress of the FSP composites was improved in the 1D and in the 2D specimens signifying a larger resistance of the product metal under high stress conditions without deforming. The tensile strength was shown to increase along with the yield stress. | 1 | Applied and Interdisciplinary Chemistry |
A carbon sink is a natural or artificial process that "removes a greenhouse gas, an aerosol or a precursor of a greenhouse gas from the atmosphere". These sinks form an important part of the natural carbon cycle. An overarching term is carbon pool, which is all the places where carbon on Earth can be, i.e. the atmosphere, oceans, soil, plants, and so forth. A carbon sink is a type of carbon pool that has the capability to take up more carbon from the atmosphere than it releases.
Globally, the two most important carbon sinks are vegetation and the ocean. Soil is an important carbon storage medium. Much of the organic carbon retained in the soil of agricultural areas has been depleted due to intensive farming. Blue carbon designates carbon that is fixed via certain marine ecosystems. Coastal blue carbon includes mangroves, salt marshes and seagrasses. These make up a majority of ocean plant life and store large quantities of carbon. Deep blue carbon is located in international waters and includes carbon contained in "continental shelf waters, deep-sea waters and the sea floor beneath them".
For climate change mitigation purposes, the enhancement of natural carbon sinks, mainly soils and forests, is important. In the past, human practices like deforestation and industrial agriculture have depleted natural carbon sinks. This kind of land use change has been one of the causes of climate change. | 0 | Theoretical and Fundamental Chemistry |
There are other forms of metastable iron carbides that have been identified in tempered steel and in the industrial Fischer–Tropsch process. These include epsilon (ε) carbide, hexagonal close-packed FeC, precipitates in plain-carbon steels of carbon content > 0.2%, tempered at 100–200 °C. Non-stoichiometric ε-carbide dissolves above ~200 °C, where Hägg carbides and cementite begin to form. Hägg carbide, monoclinic FeC, precipitates in hardened tool steels tempered at 200–300 °C. It has also been found naturally as the mineral Edscottite in the Wedderburn meteorite | 1 | Applied and Interdisciplinary Chemistry |
The osmotic stress technique is a method for measuring the effect of water on biological molecules, particularly enzymes. Just as the properties of molecules can depend on the presence of salts, pH, and temperature, they can depend significantly on the amount of water present. In the osmotic stress technique, flexible neutral polymers such as polyethylene glycol and dextran are added to the solution containing the molecule of interest, replacing a significant part of the water. The amount of water replaced is characterized by the chemical activity of water. | 1 | Applied and Interdisciplinary Chemistry |
C. albicans is a yeast with a particular feature: it translates the CUG codon into serine rather than leucine. Due to this different codon usage it is difficult to use the model system S. cerevisiae as a Y2H to check for protein-protein interactions using C. albicans genes. To provide a more native environment a C. albicans two-hybrid (C2H) system was developed. With this system protein-protein interactions can be studied in C. albicans itself. A recent addition was the creation of a high-throughput system. | 1 | Applied and Interdisciplinary Chemistry |
Vector magnetometers measure one or more components of the magnetic field electronically. Using three orthogonal magnetometers, both azimuth and dip (inclination) can be measured. By taking the square root of the sum of the squares of the components the total magnetic field strength (also called total magnetic intensity, TMI) can be calculated by the Pythagorean theorem.
Vector magnetometers are subject to temperature drift and the dimensional instability of the ferrite cores. They also require leveling to obtain component information, unlike total field (scalar) instruments. For these reasons they are no longer used for mineral exploration. | 0 | Theoretical and Fundamental Chemistry |
An N-body treatment accounting for all impact parameters can be performed by taking into account a few simple facts. The main two ones are: (i) The above change in perpendicular velocity is the lowest order approximation in 1/b of a full Rutherford deflection. Therefore, the above perturbative theory can also be done by using this full deflection. This makes the calculation correct up to the smallest impact parameters where this full deflection must be used. (ii) The effect of Debye shielding for large impact parameters can be accommodated by using a Debye-shielded Coulomb potential (Screening effect Debye length). This cancels the above divergence at large impact parameters. The above Coulomb logarithm turns out to be modified by a constant of order unity. | 0 | Theoretical and Fundamental Chemistry |
Different methodologies can be used to assess the carbon intensity of a process. Among the most used methodologies there are:
* The whole life-cycle assessment (LCA): this includes not only the carbon emissions due to a specific process, but also those due to the production and end-of-life of materials, plants and machineries used for the considered process. This is a quite complex method, requiring a big set of variables.
* The well-to-wheels (WTW), commonly used in the Energy and Transport sectors: this is a simplified LCA considering the emissions of the process itself, the emissions due to the extraction and refining of the material (or fuel) used in the process (also "Upstream emissions"), but excluding the emissions due to the production and end-of-life of plants and machineries. This methodology is used, in the US, by the GREET model and in Europe in the [http://iet.jrc.ec.europa.eu/about-jec/jec-well-wheels-analyses-wtw JEC WTW] .
* WTW-LCA hybrid methods, trying to fill in the gap between the WTW and LCA methods. In example, for an Electric Vehicle, an hybrid method considering also the GHG due to the manufacturing and the end of life of the battery gives GHG emissions 10–13% higher, compared to the WTW
* Methods not considering LCA aspects but only the emissions occurring during a specific process; i.e. just the combustion of a fuel in a power plant, without considering the Upstream emissions.
Different calculation methods can lead to different results. The results can largely vary also for different geographic regions and timeframes (see, in example, [http://www.sciencedirect.com/science/article/pii/S1361920916307933 how C.I. of electricity varies, for different European countries, and how varied in a few years]: from 2009 to 2013 the C.I. of electricity in the European Union fell on average by 20%, So while comparing different values of Carbon Intensity it is important to correctly consider all the boundary conditions (or initial hypotheses) considered for the calculations. For example, Chinese oil fields emit between 1.5 and more than 40 g of CO per MJ with about 90% of all fields emitting 1.5–13.5 g CO. Such highly skewed carbon intensity patterns necessitate disaggregation of seemingly homogeneous emission activities and proper consideration of many factors for understanding. | 1 | Applied and Interdisciplinary Chemistry |
Stream restoration activities may range from the simple improvement or removal of a structure that inhibits natural stream functions (e.g. repairing or replacing a culvert, or removing barriers to fish passage such as weirs), to the stabilization of stream banks, or other interventions such as riparian zone restoration or the installation of stormwater-management facilities like constructed wetlands. The use of recycled water to augment stream flows that have been depleted as a result of human activities can also be considered a form of stream restoration. When present, navigation locks have a potential to be operated as vertical slot fishways to restore fish passage to some extent for a wide range of fish, including poor swimmers.
Stream-restoration projects normally begin with an assessment of a focal stream system, including climatic data, geology, watershed hydrology, stream hydraulics, sediment transport patterns, channel geometry, historical channel mobility, and flood records. Numerous systems exist to classify streams according to their geomorphology. This preliminary assessment helps to understand the stream dynamics and determining the cause of the observed degradation to be addressed; it can also be used to determine the target state for the intended restoration work, especially since the "natural" or undisturbed state is sometimes no longer achievable due to various constraints.
Two broad approaches to stream restoration have been defined in the past decades: form-based restoration and process-based restoration. Whereas the former focuses on the restoration of structural features and/or patterns considered to be characteristic of the target stream system, the latter is based on the restoration of hydrological and geomorphological processes (such as sediment transport or connectivity between the channel and the floodplain) to ensure a stream's resilience and ecological health. | 1 | Applied and Interdisciplinary Chemistry |
Originally isolated from Pennicillum compactum in 1969, brevianamide A has shown insecticidal activity. Further studies showed that a minor secondary metabolite, brevianamide B, has an epimeric center at the spiro-indoxyl quaternary center. Both were found to fluoresce under long-wave ultraviolet radiation. Furthermore, under irradaton, brevianamide A has been shown to isomerize to brevianamide B. | 0 | Theoretical and Fundamental Chemistry |
The raw material was bar iron, or (from the introduction of mild steel in the late 19th century), a bar of steel. This was drawn into a flat bar (known as a tin bar) at the ironworks or steel works where it was made. The cross-section of the bar needed to be accurate in size as this would be the cross-section of the pack of plates made from it. The bar was cut to the correct length (being the width of the plates) and heated. It was then passed four or five times through the rolls of the rolling mill, to produce a thick plate about 30 inches long. Between each pass the plate is passed over (or round) the rolls, and the gap between the rolls is narrowed by means of a screw.
This was then rolled until it had doubled in length. The plate was then folded in half (doubled) using a doubling shear, which was like a table where one half of the surface folds over on top of the other. It is then put into a furnace to be heated until it is well soaked. This is repeated until there is a pack of 8 or 16 plates. The pack is then allowed to cool. When cool, the pack was sheared (using powered shears) and the plates separated by openers (usually women). Defective plates were discarded, and the rest passed to the pickling department.
In the pickling department, the plates were immersed in baths of acid (to remove scale, i.e., oxide), then in water (washing them). After inspection they were placed in an annealing furnace, where they were heated for 10–14 hours. This was known as black pickling and black annealing. After being removed they were allowed to cool for up to 48 hours. The plates were then rolled cold through highly polished rolls to remove any unevenness and give them a polished surface. They were then annealed again at a lower temperature and pickled again, this being known as white annealing and white pickling. They were then washed and stored in slightly acid water (where they would not rust) awaiting tinning.
The tinning set consisted of two pots with molten tin (with flux on top) and a grease pot. The flux dries the plate and prepares it for the tin to adhere. The second tin pot (called the wash pot) had tin at a lower temperature. This is followed by the grease pot (containing an oil), removing the excess tin. Then follow cleaning and polishing processes. Finally, the tinplates were packed in boxes of 112 sheets ready for sale. Single plates were 14 inches by 20 inches; doubles twice that. A box weighed approximately a hundredweight.
What is described here is the process as employed during the 20th century. The process grew somewhat in complexity with the passage of time, as gradually it was found that the inclusion of additional procedures improved quality. The practice of hot rolling and then cold rolling evidently goes back to the early days, as the Knight family's tinplate works had (from its foundation in about 1740) two rolling mills, one at Bringewood (west of Ludlow) which made blackplate, and the other the tin mill at Mitton (now part of Stourport), evidently for the later stages. | 1 | Applied and Interdisciplinary Chemistry |
Of the known types of bronze or brass, not distinguished in classical antiquity and interchangeably known in Latin as aes and in Greek as χαλκός, Corinthian bronze was the most valuable. Statues, vases and vessels, or other objects formed of this metal were priceless, of greater value than if they had been made of silver or gold. Pliny the Elder distinguished it into three kinds, depending on the metal that is added to the copper base: in the first, gold is added (luteum); in the second, silver (candidum); in the third, gold, silver, and copper are equally blended. Plutarch and Cicero both comment that Corinthian bronze, unlike many other copper alloys, is resistant to tarnishing. Pliny also refers to a fourth, dark alloy, known as hepatizon. Petronius and other authors mocked the connoisseurs of their day who claimed to be able to identify it.
According to legend, Corinthian bronze was first created by accident, during the burning of Corinth by Lucius Mummius Achaicus in 146 BC, when the city's immense quantities of gold, silver, and copper melted together. Pliny however, remarked that this story is unbelievable, because most of the creators of the highly valued works in Corinthian bronze in Ancient Greece lived at a much earlier period than second century BC. According to Pliny, the method of making it had been lost for a long time, although some sources describe the process by which it is created, involving heat treatment, quenching, leaching, and burnishing, in a process similar to depletion gilding. The lost ability to give an object made from bronze the appearance of gold or silver may be one strand behind the later alchemical quest to turn base metals into precious metals. | 1 | Applied and Interdisciplinary Chemistry |
A venturi siphon, also known as an eductor, is not a siphon but a form of vacuum pump using the Venturi effect of fast flowing fluids (e.g. air), to produce low pressures to suction other fluids; a common example is the carburetor. See pressure head. The low pressure at the throat of the venturi is called a siphon when a second fluid is introduced, or an aspirator when the fluid is air, this is an example of the misconception that air pressure is the operating force for siphons. | 1 | Applied and Interdisciplinary Chemistry |
The simplest approach and still one of the most common techniques is known as pump–probe spectroscopy. In this method, two or more optical pulses with variable time delay between them are used to investigate the processes happening during a chemical reaction. The first pulse (pump) initiates the reaction, by breaking a bond or exciting one of the reactants. The second pulse (probe) is then used to interrogate the progress of the reaction a certain period of time after initiation. As the reaction progresses, the response of the reacting system to the probe pulse will change. By continually scanning the time delay between pump and probe pulses and observing the response, workers can reconstruct the progress of the reaction as a function of time. | 0 | Theoretical and Fundamental Chemistry |
Inductive cleavage, in organic chemistry, is the charge-initiated counterpoint to radical initiated alpha-cleavage. Since inductive cleavage does not require unpairing and re-pairing electrons it can occur at both radical cationic and cationic sites. | 0 | Theoretical and Fundamental Chemistry |
* COGEMA La Hague site
* Mayak
* Thermal Oxide Reprocessing Plant and B205 at Sellafield
* Tokai, Ibaraki
* West Valley Reprocessing Plant
* Savannah River Site
* Hanford Site
* Idaho Chemical Processing Plant, (now Idaho National Laboratory)
* Radiochemical Engineering Development Center, Oak Ridge National Laboratory | 0 | Theoretical and Fundamental Chemistry |
In MEMO, initialization is performed with suitable diagnostic methods: a mass-consistent initial wind field is formulated using an objective analysis model and scalar fields are initialized using appropriate interpolating techniques (Kunz, R., 1991). Data needed to apply the diagnostic methods may be derived either from observations or from larger scale simulations.
Suitable boundary conditions have to be imposed for the wind velocity components , and , the potential temperature and pressure at all boundaries. At open boundaries, wave reflection and deformation may be minimized by the use of so-called radiation conditions (Orlanski 1976).
According to the experience gained so far with the model MEMO, neglecting large scale environmental information might result in instabilities in case of simulations over longer time periods.
For the nonhydrostatic part of the mesoscale pressure perturbation, homogeneous Neumann boundary conditions are used at lateral boundaries. With these conditions, the wind velocity component perpendicular to the boundary remains unaffected by the pressure change.
At the upper boundary, Neumann boundary conditions are imposed for the horizontal velocity components and the potential temperature. To ensure non-reflectivity, a radiative condition is used for the hydrostatic part of the mesoscale pressure perturbation
at that boundary. Hence, vertically propagating internal gravity waves are allowed to leave the computational domain (Klemp and Durran 1983). For the nonhydrostatic part of the mesoscale pressure perturbation, homogeneous staggered Dirichlet conditions are imposed. Being justified by the fact that nonhydrostatic effects are negligible at large heights, this condition is necessary, if singularity of the elliptic pressure equation is to be avoided in view of the Neumann boundary conditions at all other boundaries.
The lower boundary coincides with the ground (or, more precisely, a height above ground corresponding to its aerodynamic roughness). For the non-hydrostatic part of the mesoscale pressure perturbation, inhomogeneous Neumann conditions are imposed at that boundary. All other conditions at the lower boundary follow from the assumption that the –Obukhov similarity theory is valid.
The one way interactive nesting facility is possible within MEMO. Thus, successive simulations on grids of increasing resolution are possible. During these simulations, the results of the application to a coarse grid are used as boundary conditions for the application to the finer grid (Kunz and Moussiopoulos, 1995). | 1 | Applied and Interdisciplinary Chemistry |
Glycogenin-1 is an enzyme that is involved in the biosynthesis of glycogen. It is capable of self-glucosylation, forming an oligosaccharide primer that serves as a substrate for glycogen synthase. This is done through an inter-subunit mechanism. It also plays a role in glycogen metabolism regulation. Recombinant human glycogenin-1 was expressed in E. coli and purified using conventional chromatography techniques. | 1 | Applied and Interdisciplinary Chemistry |
Haploid cells are one of two mating types (a or α), and respond to the mating pheromone produced by haploid cells of the opposite mating type, and can mate with cells of the opposite mating type. Haploid cells cannot undergo meiosis. Diploid cells do not produce or respond to either mating pheromone and do not mate, but can undergo meiosis to produce four haploid cells.
Like the differences between haploid a and α cells, different patterns of gene repression and activation are responsible for the phenotypic differences between haploid and diploid cells. In addition to the specific a and α transcriptional patterns, haploid cells of both mating types share a haploid transcriptional pattern which activates haploid-specific genes (such as HO) and represses diploid-specific genes (such as IME1). Similarly, diploid cells activate diploid-specific genes and repress haploid-specific genes.
The different gene expression patterns of haploids and diploids are again due to the MAT locus. Haploid cells only contain one copy of each of the 16 chromosomes and thus can only possess one allele of MAT (either MATa or MATα), which determines their mating type. Diploid cells result from the mating of an a cell and an α cell, and thus possess 32 chromosomes (in 16 pairs), including one chromosome bearing the MATa allele and another chromosome bearing the MATα allele. The combination of the information encoded by the MATa allele (the a1 gene) and the MATα allele (the α1 and α2 genes) triggers the diploid transcriptional program. Similarly, the presence of only a single allele of MAT, whether it is MATa or MATα, triggers the haploid transcriptional program.
The alleles present at the MAT locus are sufficient to program the mating behaviour of the cell. For example, using genetic manipulations, a MATa allele can be added to a MATα haploid cell. Despite having a haploid complement of chromosomes, the cell now has both the MATa and MATα alleles, and will behave like a diploid cell: it will not produce or respond to mating pheromones, and when starved will attempt to undergo meiosis, with fatal results. Similarly, deletion of one copy of the MAT locus in a diploid cell, leaving only a single MATa or MATα allele, will cause a cell with a diploid complement of chromosomes to behave like a haploid cell. | 1 | Applied and Interdisciplinary Chemistry |
Sulfuric acid is rarely encountered naturally on Earth in anhydrous form, due to its great affinity for water. Dilute sulfuric acid is a constituent of acid rain, which is formed by atmospheric oxidation of sulfur dioxide in the presence of water – i.e. oxidation of sulfurous acid. When sulfur-containing fuels such as coal or oil are burned, sulfur dioxide is the main byproduct (besides the chief products carbon oxides and water).
Sulfuric acid is formed naturally by the oxidation of sulfide minerals, such as pyrite:
The resulting highly acidic water is called acid mine drainage (AMD) or acid rock drainage (ARD).
The can be further oxidized to :
The produced can be precipitated as the hydroxide or hydrous iron oxide:
The iron(III) ion ("ferric iron") can also oxidize pyrite:
When iron(III) oxidation of pyrite occurs, the process can become rapid. pH values below zero have been measured in ARD produced by this process.
ARD can also produce sulfuric acid at a slower rate, so that the acid neutralizing capacity (ANC) of the aquifer can neutralize the produced acid. In such cases, the total dissolved solids (TDS) concentration of the water can be increased from the dissolution of minerals from the acid-neutralization reaction with the minerals.
Sulfuric acid is used as a defense by certain marine species, for example, the phaeophyte alga Desmarestia munda (order Desmarestiales) concentrates sulfuric acid in cell vacuoles. | 0 | Theoretical and Fundamental Chemistry |
Polymer surfaces differ from non-polymer surfaces in that the subunits that make up the surface are covalently bonded to one another. Non-polymer surfaces can be bound by ionic bonds, metallic bonds or intermolecular forces (IMFs). In a two component system, non-polymer surfaces form when a positive net amount of energy is required to break self-interactions and form non-self-interactions. Therefore, the energy of mixing (ΔG) is positive. This amount of energy, as described by interfacial tension, varies for different combinations of materials. However, with polymer surfaces, the subunits are covalently bonded together and the bulk phase of the solid surface does not allow for surface tension to be measured directly. The intermolecular forces between the large polymer molecules are difficult to calculate and cannot be determined as easily as non-polymer surface molecular interactions. The covalently bonded subunits form a surface with differing properties as compared to non-polymer surfaces. Some examples of polymer surfaces include: polyvinyl chloride (PVC), nylon, polyethylene (PE), and polypropylene (PP). Polymer surfaces have been analyzed using a variety of techniques, including: scanning electron microscopy, scanning tunneling microscopy, and infrared spectroscopy. | 0 | Theoretical and Fundamental Chemistry |
The Lattice Boltzmann methods for solids (LBMS) are a set of methods for solving partial differential equations (PDE) in solid mechanics. The methods use a discretization of the Boltzmann equation(BM), and their use is known as the lattice Boltzmann methods for solids.
LBMS methods are categorized by their reliance on:
* Vectorial distributions
* Wave solvers
* Force tuning
The LBMS subset remains highly challenging from a computational aspect as much as from a theoretical point of view. Solving solid equations within the LBM framework is still a very active area of research. If solids are solved, this shows that the Boltzmann equation is capable of describing solid motions as well as fluids and gases: thus unlocking complex physics to be solved such as fluid-structure interaction (FSI) in biomechanics. | 0 | Theoretical and Fundamental Chemistry |
β adrenergic receptor antagonists (also called beta-blockers or β-blockers) were initially developed in the 1960s, for the treatment of angina pectoris but are now also used for hypertension, congestive heart failure and certain arrhythmias. In the 1950s, dichloroisoproterenol (DCI) was discovered to be a β-antagonist that blocked the effects of sympathomimetic amines on bronchodilation, uterine relaxation and heart stimulation. Although DCI had no clinical utility, a change in the compound did provide a clinical candidate, pronethalol, which was introduced in 1962. | 1 | Applied and Interdisciplinary Chemistry |
Siwy is from Poland. She studied chemistry at the Silesian University of Technology in Poland. She graduated with a master's degree in polymer technology in 1995, before completing a doctorate in chemical sciences in 1997. Siwy was a postdoctoral scholar at the University of Florida. | 0 | Theoretical and Fundamental Chemistry |
In 1738 Daniel Bernoulli published his Hydrodynamica seu de viribus et motibus fluidorum commentarii. His theory of the motion of fluids, the germ of which was first published in his memoir entitled Theoria nova de motu aquarum per canales quocunque fluentes, communicated to the academy of St Petersburg as early as 1726, was founded on two suppositions, which appeared to him conformable to experience. He supposed that the surface of the fluid, contained in a vessel which is emptying itself by an orifice, remains always horizontal; and, if the fluid mass is conceived to be divided into an infinite number of horizontal strata of the same bulk, that these strata remain contiguous to each other, and that all their points descend vertically, with velocities inversely proportional to their breadth, or to the horizontal sections of the reservoir. In order to determine the motion of each stratum, he employed the principle of the conservatio virium vivarum, and obtained very elegant solutions. But in the absence of a general demonstration of that principle, his results did not command the confidence which they would otherwise have deserved, and it became desirable to have a theory more certain, and depending solely on the fundamental laws of mechanics. Colin Maclaurin and John Bernoulli, who were of this opinion, resolved the problem by more direct methods, the one in his Fluxions, published in 1742, and the other in his Hydraulica nunc primum detecta, et demonstrata directe ex fundamentis pure mechanicis, which forms the fourth volume of his works. The method employed by Maclaurin has been thought not sufficiently rigorous; and that of John Bernoulli is, in the opinion of Lagrange, defective in clearness and precision. | 1 | Applied and Interdisciplinary Chemistry |
Naturally occurring restriction endonucleases are categorized into five groups (Types I, II, III, IV, and V) based on their composition and enzyme cofactor requirements, the nature of their target sequence, and the position of their DNA cleavage site relative to the target sequence. DNA sequence analysis of restriction enzymes however show great variations, indicating that there are more than four types. All types of enzymes recognize specific short DNA sequences and carry out the endonucleolytic cleavage of DNA to give specific fragments with terminal 5'-phosphates. They differ in their recognition sequence, subunit composition, cleavage position, and cofactor requirements, as summarised below:
* Type I enzymes () cleave at sites remote from a recognition site; require both ATP and S-adenosyl-L-methionine to function; multifunctional protein with both restriction digestion and methylase () activities.
* Type II enzymes () cleave within or at short specific distances from a recognition site; most require magnesium; single function (restriction digestion) enzymes independent of methylase.
* Type III enzymes () cleave at sites a short distance from a recognition site; require ATP (but do not hydrolyse it); S-adenosyl-L-methionine stimulates the reaction but is not required; exist as part of a complex with a modification methylase ().
* Type IV enzymes target modified DNA, e.g. methylated, hydroxymethylated and glucosyl-hydroxymethylated DNA
* Type V enzymes utilize guide RNAs (gRNAs) | 1 | Applied and Interdisciplinary Chemistry |
PEP carboxylase is mainly subject to two levels of regulation: phosphorylation and allostery. Figure 3 shows a schematic of the regulatory mechanism.
Phosphorylation by phosphoenolpyruvate carboxylase kinase turns the enzyme on, whereas phosphoenolpyruvate carboxylase phosphatase turns it back off. Both kinase and phosphatase are regulated by transcription. It is further believed that malate acts as a feedback inhibitor of kinase expression levels, and as an activator for phosphatase expression (transcription). Since oxaloacetate is converted to malate in CAM and organisms, high concentrations of malate activate phosphatase expression - the phosphatase subsequently de-phosphorylates and thus de-actives PEP carboxylase, leading to no further accumulation of oxaloacetate and thus no further conversion of oxaloacetate to malate. Hence malate production is down-regulated.
The main allosteric inhibitors of PEP carboxylase are the carboxylic acids malate (weak) and aspartate (strong). Since malate is formed in the next step of the CAM and cycles after PEP carboxylase catalyses the condensation of CO and PEP to oxaloacetate, this works as a feedback inhibition pathway. Oxaloacetate and aspartate are easily inter-convertible through a transaminase mechanism; thus high concentrations of aspartate are also a pathway of feedback inhibition of PEP carboxylase.
The main allosteric activators of PEP carboxylase are acetyl-CoA and fructose-1,6-bisphosphate (F-1,6-BP). Both molecules are indicators of increased glycolysis levels, and thus positive feed-forward effectors of PEP carboxylase. They signal the need to produce oxaloacetate to allow more flux through the citric acid cycle. Additionally, increased glycolysis means a higher supply of PEP is available, and thus more storage capacity for binding CO in transport to the Calvin cycle. It is also noteworthy that the negative effectors aspartate competes with the positive effector acetyl-CoA, suggesting that they share an allosteric binding site.
Studies have shown that energy equivalents such as AMP, ADP and ATP have no significant effect on PEP carboxylase.
The magnitudes of the allosteric effects of these different molecules on PEP carboxylase activity depend on individual organisms. | 0 | Theoretical and Fundamental Chemistry |
Around 2 Ga, an increase in atmospheric oxygen levels took place, causing an oxidation of HS in the surroundings, and an increase in the pH of the sea water. The resulting environment had become more oxidizing and thus allowed the later incorporation of the heavier metals such as copper and zinc. | 0 | Theoretical and Fundamental Chemistry |
Insensitive nuclei enhancement by polarization transfer (INEPT) is a signal enhancement method used in NMR spectroscopy. It involves the transfer of nuclear spin polarization from spins with large Boltzmann population differences to nuclear spins of interest with lower Boltzmann population differences. INEPT uses J-coupling for the polarization transfer in contrast to Nuclear Overhauser effect (NOE), which arises from dipolar cross-relaxation. This method of signal enhancement was introduced by Ray Freeman in 1979. Due to its usefulness in signal enhancement, pulse sequences used in heteronuclear NMR experiments often contain blocks of INEPT or INEPT-like sequences. | 0 | Theoretical and Fundamental Chemistry |
The NNRTIs act by binding non-competitively to the RT enzyme (figure 3). The binding causes conformational change in the three-dimensional structure of the enzyme and creates the NNIBP. Binding of NNRTI to HIV-1 RT makes the p66 thumb domain hyper extended because it induces rotamer conformation changes in amino acid residues Tyr-181 and Tyr-188. This affects the catalytic activity of the enzyme and blocks the HIV-1 replication by inhibiting the polymerase active site of the RT's p66 subunit. The global conformational change additionally destabilizes the enzyme on its nucleic acid template and reduces its ability to bind nucleotides. The transcription of the viral RNA is inhibited and therefore the replication rate of the virus reduces. Although the exact molecular mechanism is still hypothetical this has been demonstrated by multiple studies to be the primary mechanism of action.
In addition to this proposed primary mechanism of action it has been shown that the NNRTIs have other mechanisms of action and interfere with various steps in the reverse transcriptase reaction. It has been suggested that the inhibition of reverse transcription by the NNRTIs may be due to effects on the RT Rnase H activity and/or template/primer binding. Some NNRTIs interfere with HIV-1 Gag-Pol polyprotein processing by inhibiting the late stage of HIV-1 replication.
It is important to gain profound understanding of the various mechanism of action of the NNRTIs in order to develop next-generation NNRTIs and for understanding the mechanism of drug resistance. | 1 | Applied and Interdisciplinary Chemistry |
Today, the IIR has 59 member countries representing over two-thirds of the global population.
According to their annual financial contributions to the IIR, these member countries are divided into six category levels and this determines the services they receive and their level of voting power within the IIR. Member Countries take part in IIR activities via their delegates and their nominated commission members. The delegates and commission members determine IIR priorities and take part in the IIR scientific activities and Working Groups, and develop recommendations. Member countries are entitled to host several IIR conferences and meetings per year. | 0 | Theoretical and Fundamental Chemistry |
In 2019 it was reported that ordinary graphite exhibits second sound at 120 K. This feature was both predicted theoretically and observed experimentally, and
was by far the highest temperature at which second sound has been observed. However, this second sound is observed only at the microscale, because the wave dies out exponentially with
characteristic length 1-10 microns. Therefore, presumably graphite in the right temperature regime has extraordinarily high thermal conductivity but only for the purpose of transferring heat pulses distances of order 10 microns, and for pulses of duration on the order of 10 nanoseconds. For more "normal" heat-transfer, graphite's observed thermal conductivity is less than that of, e.g., copper. The theoretical models, however, predict longer absorption lengths would be seen in isotopically pure graphite, and perhaps over a wider temperature range, e.g. even at room temperature. (As of March 2019, that experiment has not yet been tried.) | 0 | Theoretical and Fundamental Chemistry |
In mid-March 1989, both research teams were ready to publish their findings, and Fleischmann and Jones had agreed to meet at an airport on 24 March to send their papers to Nature via FedEx. Fleischmann and Pons, however, pressured by the University of Utah, which wanted to establish priority on the discovery, broke their apparent agreement, disclosing their work at a press conference on 23 March (they claimed in the press release that it would be published in Nature but instead submitted their paper to the Journal of Electroanalytical Chemistry). Jones, upset, faxed in his paper to Nature after the press conference.
Fleischmann and Pons' announcement drew wide media attention. But the 1986 discovery of high-temperature superconductivity had made the scientific community more open to revelations of unexpected scientific results that could have huge economic repercussions and that could be replicated reliably even if they had not been predicted by established theories. Many scientists were also reminded of the Mössbauer effect, a process involving nuclear transitions in a solid. Its discovery 30 years earlier had also been unexpected, though it was quickly replicated and explained within the existing physics framework.
The announcement of a new purported clean source of energy came at a crucial time: adults still remembered the 1973 oil crisis and the problems caused by oil dependence, anthropogenic global warming was starting to become notorious, the anti-nuclear movement was labeling nuclear power plants as dangerous and getting them closed, people had in mind the consequences of strip mining, acid rain, the greenhouse effect and the Exxon Valdez oil spill, which happened the day after the announcement. In the press conference, Chase N. Peterson, Fleischmann and Pons, backed by the solidity of their scientific credentials, repeatedly assured the journalists that cold fusion would solve environmental problems, and would provide a limitless inexhaustible source of clean energy, using only seawater as fuel. They said the results had been confirmed dozens of times and they had no doubts about them. In the accompanying press release Fleischmann was quoted saying: "What we have done is to open the door of a new research area, our indications are that the discovery will be relatively easy to make into a usable technology for generating heat and power, but continued work is needed, first, to further understand the science and secondly, to determine its value to energy economics." | 0 | Theoretical and Fundamental Chemistry |
Following the Peoples National Movements defeat in the 2010 general election, Rowley was appointed as Leader of the Opposition on the 1st June. He was then elected political leader of the People's National Movement as he was seen as the most capable to lead the party. As political leader he advocated implementation of the one man, one vote system within the party. Rowley has served on several parliamentary committees. In 2004, he chaired the Joint Select Committee of Parliament which examined and made recommendations for the live broadcasting of parliamentary debates. He served as the representative governor of Trinidad and Tobago for the Inter-American Development Bank and the Caribbean Development Bank. | 0 | Theoretical and Fundamental Chemistry |
Nanoparticles of certain materials can be created by "wet" chemical processes, in which solutions of suitable compounds are mixed or otherwise treated to form an insoluble precipitate of the desired material. The size of the particles of the latter is adjusted by choosing the concentration of the reagents and the temperature of the solutions, and through the addition of suitable inert agents that affect the viscosity and diffusion rate of the liquid. With different parameters, the same general process may yield other nanoscale structures of the same material, such as aerogels and other porous networks.
The nanoparticles formed by this method are then separated from the solvent and soluble byproducts of the reaction by a combination of evaporation, sedimentation, centrifugation, washing, and filtration.Alternatively, if the particles are meant to be deposited on the surface of some solid substrate, the starting solutions can be by coated on that surface by dipping or spin-coating, and the reaction can be carried out in place.
Electroless deposition provides a unique opportunity for growing nanoparticles onto surface without the need for costly spin coating, electrodeposition, or physical vapor deposition. Electroless deposition processes can form colloid suspensions catalytic metal or metal oxide deposition. The suspension of nanoparticles that result from this process is an example of colloid. Typical instances of this method are the production of metal oxide or hydroxide nanoparticles by hydrolysis of metal alkoxides and chlorides.
Besides being cheap and convenient, the wet chemical approach allows fine control of the particle's chemical composition. Even small quantities of dopants, such as organic dyes and rare earth metals, can be introduced in the reagent solutions end up uniformly dispersed in the final product. | 0 | Theoretical and Fundamental Chemistry |
The slightly kinked diagonal line on the main part of the map is known as the surge (or stall) line. Above this line is a region of unstable flow, which is an area best avoided.
A compressor surge or compressor stall causes an abrupt reversal of airflow in the compressor. Compressor blades create a pumping action by working as airfoils. In a surge or stall, blades experience an aerodynamic stall (similar to an aircraft wing stalling) and become unable to hold back the higher pressure downstream, with a resulting violent flow reversal. The flame which is normally confined in the combustion chamber may come out of the engine inlet as well as the exhaust nozzle. | 0 | Theoretical and Fundamental Chemistry |
The term azeotrope is derived from the Greek words ζέειν (boil) and τρόπος (turning) with the prefix α- (no) to give the overall meaning, "no change on boiling". The term was coined in 1911 by English chemist John Wade and Richard William Merriman. Because their composition is unchanged by distillation, azeotropes are also called (especially in older texts) constant boiling point mixtures. | 1 | Applied and Interdisciplinary Chemistry |
Median aerodynamic diameter (MAD) is one of two parameters influencing the deposition of inhaled particles, the other being the geometric standard deviation of the particle size distribution. The MAD is the value of aerodynamic diameter for which 50% of some quantity in a given aerosol is associated with particles smaller than the MAD, and 50% of the quantity is associated with particles larger than the MAD. It simplifies the true distribution of aerodynamic diameters of a given aerosol as a single value. It is also used to describe those particle sizes for which deposition depends chiefly on inertial impaction and sedimentation. | 0 | Theoretical and Fundamental Chemistry |
It is known that Middle Minoan bronze work flourished as an independent native art. To the very beginning of this epoch belongs the largest sword of the age, found in the palace of Malia. It is a flat blade, 79 cm long, with a broad base and a sharp point; there is a gold and crystal hilt but no ornament on the blade. A dagger of somewhat later date, now in the Metropolitan Museum of New York is the earliest piece of decorated bronze from Crete. Both sides of the blade are engraved with drawings: bulls fighting and a man hunting boars in a thicket. Slightly later again (MM III) are a series of blades from mainland Greece, which must be attributed to Cretan craftsmen, with ornament in relief, or incised, or inlaid with gold, silver and niello. The most elaborate inlays, pictures of men hunting lions and cats hunting birds, are on daggers from the shaftgraves of Mycenae. These large designs cover the whole of the flat blade except its edge, but on swords, best represented by finds at Knossos, the ornament is restricted to the high midribs which are an essential feature of the longer blades. The type belongs to the beginning of the Late Minoan (Mycenaean) age. The hilt is made in one piece with the blade; it has a horned guard, a flanged edge for holding grip-scales, and a tang for a pommel. The scales were ivory or some other perishable substance and were fixed with bronze rivets; the pommels were often made of crystal. A rapier from Zapher Papoura (Knossos) is 91.3 cm long; its midrib and hilt-flange are engraved with bands of spiral coils, and its rivet-heads (originally gold-cased) with whorls. Ordinary Mycenaean blades are enriched with narrow mouldings, parallel to the midribs of swords and daggers, or to the curved backs of one-edged knives. The spearheads have hammered sockets. Other tools and implements are oval two-edged knives, square-ended razors, cleavers, chisels, hammers, axes, mattocks, ploughshares and saws. Cycladic and mainland Greek (Helladic) weapons show no ornament but include some novel types. A tanged spearhead has a slit (Cycladic) or slipped (Helladic) blade for securing the shaft; and the halberd, a west European weapon, was in use in the Middle Helladic Greece. There are few remains of Mycenaean metal armour; a plain cheek-piece from a helmet comes from Ialysos in Rhodes, and a pair of greaves from Enkomi in Cyprus. One of the greaves has wire riveted to its edge for fastening. | 1 | Applied and Interdisciplinary Chemistry |
The reaction allows for alkylation of electron deficient heterocyclic species which is not possible with Friedel-Crafts chemistry. A method for alkylating electron deficient arenes, nucleophilic aromatic substitution, is also unavailable to electron deficient heterocycles as the ionic nucleophilic species used will deprotonate the heterocycle over acting as a nucleophile. Again, in contrast to nucleophilic aromatic substitution, the Minisci reaction does not require functionalisation of the arene, allowing for direct C-H functionalisation.
Further to this, the generated alkyl radical species will not rearrange during the reaction in the way that alkyl fragments appended by Friedel-Crafts alkylation often will; meaning groups such as n-pentyl and cyclopropyl groups can be added unchanged. The alkyl radical is also a soft nucleophile and so is very unlikely to interact with any hard electrophiles (carbonyl species for example) already present on the heterocycle, which increases the functional group tolerance of the reaction.
The reaction has been the subject of much research in recent years, with a focus placed on improved reactivity towards a greater variety of heterocycles, increasing the number of alkylating reagents that can be used, and employing milder oxidants and acids. | 0 | Theoretical and Fundamental Chemistry |
Metallic parts produced by casting are comparatively inexpensive, but are often subject to metallurgical flaws like porosity and microstructural defects. Friction stir processing can be used to introduce a wrought microstructure into a cast component and eliminate many of the defects. By vigorously stirring a cast metal part to homogenize it and reduce the grain size, the ductility and strength are increased. | 1 | Applied and Interdisciplinary Chemistry |
A crystallization adjutant is a material used to promote crystallization, normally in a context where a material does not crystallize naturally from a pure solution. | 0 | Theoretical and Fundamental Chemistry |
* [http://gpsprot.org GPS-Prot] Web-based data visualization for protein interactions
* PINV - [http://biosual.cbio.uct.ac.za/pinv.html Protein Interaction Network Visualizer] | 1 | Applied and Interdisciplinary Chemistry |
In epitranscriptomic sequencing, most methods focus on either (1) enrichment and purification of the modified RNA molecules before running on the RNA sequencer, or (2) improving or modifying bioinformatics analysis pipelines to call the modification peaks. Most methods have been adapted and optimized for mRNA molecules, except for modified bisulfite sequencing for profiling 5-methylcytidine which was optimized for tRNAs and rRNAs.
There are seven major classes of chemical modifications found in RNA molecules: N-methyladenosine, 2-O-methylation, N6,2-O-dimethyladenosine, 5-methylcytidine, 5-hydroxylmethylcytidine, inosine, and pseudouridine. Various sequencing methods have been developed to profile each type of modification. The scale, resolution, sensitivity, and limitations associated with each method and the corresponding bioinformatics tools used will be discussed. | 1 | Applied and Interdisciplinary Chemistry |
Acyl groups are named by stripping the "-ic acid" of the corresponding carboxylic acid and replacing it with "-yl." For example, is called ethanoyl-R. | 0 | Theoretical and Fundamental Chemistry |
Research in the RajanBabu lab is focused on development of new methodology for stereoselective synthesis. Major research areas include:
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RajanBabu developed methodology surrounding C-C bond formation via metal-catalyzed hydroformylation. They reported several asymmetric examples through the usage of chiral phosphine ligand with a hemilabile coordinating group. This method was applicable using vinylarenes, 1,3-dienes and strained olefins as substrates. Applications of this chemistry include a new synthesis of (S)-ibuprofen and a new approach to controlling the exocyclic side-chain stereochemistry in helioporin D and pseudopterocins. Related to this methodology, RajanBabu also developed a tandem [2+2] cycloaddition/asymmetric hydrovinylation reaction to allow conversion of simple precursors (ethylene, enynes) to structurally complex cyclobutanes.
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The RajanBabu group developed methodology in the area of hydrocyanation, leveraging the reaction of vinylarenes with HCN in the presence of Ni(0) complexes. Based on the phosphorus ligands within the Ni complex, the reaction can be rendered asymmetric. The enantioselectivity could be further improved by tuning the electronics of the phosphine ligands to electronically differentiate the phosphorus chelates. Electronic tuning was accomplished, for example, using widely available sugars such as D-glucose and D-fructose.
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For further information on the Nugent-RajanBabu reagent, please see Bis(cyclopentadienyl)titanium(III) chloride.
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One area of interest to the RajanBabu group is catalytic multicomponent addition/cyclization reactions. This methodology allows for formation of carbocyclic and heterocyclic compounds from acyclic precursors including unactivated olefins and acetylenes. This method leverages the reactivity of bifunctional reagents (X-Y) where X-Y in above scheme can represent RSi−SiR‘, RSi−SnR‘, RSi−BR‘, RSn−BR‘, and trialkylsilicon- and trialkyltin- hydrides. The reactions are palladium-catalyzed, and incorporation of the X and Y species allows for vast diversification of the end products. Application of this methodology afforded syntheses of highly alkylated indolizidines such as IND-223A.
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RajanBabu has evaluated asymmetric aziridine openings with high enantioselectivity using yttrium- and lanthanide- salen complexes. The RajanBabu group has also developed water-soluble Rhodium(I) complexes, allowing for reactions to be run in aqueous media. | 0 | Theoretical and Fundamental Chemistry |
Alkynyl ethers and siloxyacetylenes have proven to be the ideal pair for aromatic annulations. The reactions can be run with both activated heterosubstituted alkynes and un-activated acetlyenes. Alkynyl thioethers and ynamines have been used as reactants in the annulation reaction.
Conjugated enynes have also been used for benzannulation reactions catalyzed by cobalt. This type of benzannulation involves a [4+2] cycloaddition followed by a 1,3-hydrogen shift. In dichloromethane, the symmetrical benzannulation products are yielded but in tetrahydrofuran (THF), unsymmetrical benzannulation products were obtained with good regioselectivity. These reactions utilize 1,3-bis(diphenylphosphino)propane (dppp) substituted cobalt catalyst in the presence of powdered zinc and zinc iodide for a solvent dependent benzannulation reaction (Scheme 11). In dichloromethane the ratio of A:B is 78:22 with an overall combined yield of 90% and in THF the ratio has switched to 7:93 (A:B) with a combined yield of 85%.
Palladium-catalyzed benzannulations have been developed using allylic compounds and alkynes. This palladium catalyzed reaction has been performed in both inter- and intramolecular forms. The cationic palladium complex [(η-CH)Pd(CHCN)](BF) reacts with an excess of 4-octyne when heated to 80 °C in the presence of triphenylphosphine forming the aromatic compound 1-methyl-2,3,4,5-tetrapropylbenzene (Scheme 12). It was determined that the presence of exactly one equivalent of palladium catalyst (from which the allyl group adds into the final aromatic structure) is crucial for the catalyzed benzannulation to occur in good yield.
This catalyzed reaction was also optimized for allyl substrates with catalytic [Pd(dba)]CHCl and triphenylphosphine (dba =dibenzylideneacetone) (Scheme 13). | 0 | Theoretical and Fundamental Chemistry |
The aftermath of World War II saw an explosion in the discovery of new classes of antibacterial drugs including the cephalosporins (developed by Eli Lilly based on the seminal work of Giuseppe Brotzu and Edward Abraham), streptomycin (discovered during a Merck-funded research program in Selman Waksmans laboratory), the tetracyclines (discovered at Lederle Laboratories, now a part of Pfizer), erythromycin (discovered at Eli Lilly and Co.) and their extension to an increasingly wide range of bacterial pathogens. Streptomycin, discovered during a Merck-funded research program in Selman Waksmans laboratory at Rutgers in 1943, became the first effective treatment for tuberculosis. At the time of its discovery, sanitoriums for the isolation of tuberculosis-infected people were an ubiquitous feature of cities in developed countries, with 50% dying within 5 years of admission.
A Federal Trade Commission report issued in 1958 attempted to quantify the effect of antibiotic development on American public health. The report found that over the period 1946–1955, there was a 42% drop in the incidence of diseases for which antibiotics were effective and only a 20% drop in those for which antibiotics were not effective. The report concluded that "it appears that the use of antibiotics, early diagnosis, and other factors have limited the epidemic spread and thus the number of these diseases which have occurred". The study further examined mortality rates for eight common diseases for which antibiotics offered effective therapy (syphilis, tuberculosis, dysentery, scarlet fever, whooping cough, meningococcal infections, and pneumonia), and found a 56% decline over the same period. Notable among these was a 75% decline in deaths due to tuberculosis.
During the years 1940–1955, the rate of decline in the U.S. death rate accelerated from 2% per year to 8% per year, then returned to the historical rate of 2% per year. The dramatic decline in the immediate post-war years has been attributed to the rapid development of new treatments and vaccines for infectious disease that occurred during these years.
Vaccine development continued to accelerate, with the most notable achievement of the period being Jonas Salk's 1954 development of the polio vaccine under the funding of the non-profit National Foundation for Infantile Paralysis. The vaccine process was never patented but was instead given to pharmaceutical companies to manufacture as a low-cost generic. In 1960 Maurice Hilleman of Merck Sharp & Dohme identified the SV40 virus, which was later shown to cause tumors in many mammalian species. It was later determined that SV40 was present as a contaminant in polio vaccine lots that had been administered to 90% of the children in the United States. The contamination appears to have originated both in the original cell stock and in monkey tissue used for production. In 2004 the National Cancer Institute announced that it had concluded that SV40 is not associated with cancer in people.
Other notable new vaccines of the period include those for measles (1962, John Franklin Enders of Children's Medical Center Boston, later refined by Maurice Hilleman at Merck), Rubella (1969, Hilleman, Merck) and mumps (1967, Hilleman, Merck) The United States incidences of rubella, congenital rubella syndrome, measles, and mumps all fell by >95% in the immediate aftermath of widespread vaccination. The first 20 years of licensed measles vaccination in the U.S. prevented an estimated 52 million cases of the disease, 17,400 cases of mental retardation, and 5,200 deaths. | 1 | Applied and Interdisciplinary Chemistry |
Three major classes of charge transfer reactions can be studied at an ITIES:
*Ion transfer reactions
*Assisted ion transfer reactions
*Heterogeneous electron transfer reactions
The Nernst equation for an ion transfer reaction reads
where is the standard transfer potential defined as the Gibbs energy of transfer expressed in a voltage scale.
The Nernst equation for a single heterogeneous electron transfer reaction reads
where is the standard redox potential for the interfacial transfer of electrons defined as the difference the standard redox potentials of the two redox couples but referred to the aqueous standard hydrogen electrode (SHE). | 0 | Theoretical and Fundamental Chemistry |
Commonly silylation of alcohols requires a silyl chloride and an amine base. One reliable and rapid procedure is the Corey protocol in which the alcohol is reacted with a silyl chloride and imidazole at high concentration in DMF. If DMF is replaced by dichloromethane, the reaction is somewhat slower, but the purification of the compound is simplified. A common hindered base for use with silyl triflates is 2,6-lutidine. Primary alcohols can be protected in less than one hour while some hindered alcohols may require days of reaction time.
When using a silyl chloride, no special precautions are usually required, except for the exclusion of large amounts of water. An excess of silyl chloride can be employed but is not necessary. If excess reagent is used, the product will require flash chromatography to remove excess silanol and siloxane.
Sometimes silyl triflate and a hindered amine base are used. Silyl triflates are more reactive than their corresponding chlorides, so they can be used to install silyl groups onto hindered positions. Silyl triflate is more reactive and also converts ketones to silyl enol ethers. Silyl triflates are water sensitive and must be run under inert atmosphere conditions. Purification involves the addition of an aqueous acid such as saturated ammonium chloride solution. Water quenches remaining silyl reagent and protonates amine bases prior to their removal from the reaction mixture. Following extraction, the product can be purified by flash chromatography.
Ketones react with hydrosilanes in the presence of metal catalysts. | 0 | Theoretical and Fundamental Chemistry |
The reductive processes discussed above can be enhanced in two ways. One is by increasing the amount of usable iron in the subsurface to increase the rate of the reduction by chemical or biological means. The second method is to enhance the reducing ability of the iron by coupling it with other chemical reductants or using biological reduction with it. Using this processes, scientists combined sodium dithionite with iron to treat Chrominum VI and TCE effectively.
Combining bacterial action and biological processes with iron is also known to be effective. The most evident uses of biological processes are with the EZVI technology created by NASA and with the EHC product created by Adventus. Both of these materials have iron within some biological matrix (iron is suspended in vegetable oil in EZVI and in organic carbon in EHC) and use microbial organisms to enhance the reduction zone and to create a more anaerobic environment for the reactions to take place in. | 1 | Applied and Interdisciplinary Chemistry |
Examples of sulfones in pharmacology include dapsone, a drug formerly used as an antibiotic to treat leprosy, dermatitis herpetiformis, tuberculosis, or pneumocystis pneumonia (PCP). Several of its derivatives, such as promin, have similarly been studied or actually been applied in medicine, but in general sulfones are of far less prominence in pharmacology than for example the sulfonamides. | 0 | Theoretical and Fundamental Chemistry |
According to the Malaysian Food Act 1983 and Regulations (as of 5 January 2010), ractopamine is allowed in pig muscle and fat (MRL of 10 ppb), pig liver (MRL of 40 ppb), and pig kidney (MRL of 90 ppb). Ractopamine is allowed as its half-life is lower, leading to reduced residues in the food, and the dose required to affect humans is much higher than other beta agonists. On 30 December 2008, the Malaysian Veterinary Services Department quarantined 10 of the 656 pig farms in Malaysia, as the livestock were found to contain the banned chemical. | 0 | Theoretical and Fundamental Chemistry |
A major pathway of induced health effects arises from spills or leaks of solvents, especially chlorinated solvents, that reach the underlying soil. Since solvents readily migrate substantial distances, the creation of widespread soil contamination is not uncommon; this is particularly a health risk if aquifers are affected. Vapor intrusion can occur from sites with extensive subsurface solvent contamination. | 1 | Applied and Interdisciplinary Chemistry |
Venturi tubes are more expensive to construct than simple orifice plates, and both function on the same basic principle. However, for any given differential pressure, orifice plates cause significantly more permanent energy loss. | 1 | Applied and Interdisciplinary Chemistry |
In bacteria, HMP-P arises by conversion of the purine biosynthetic precursor 5-aminoimidazole ribotide (AIR) through the action of enzymes such as phosphomethylpyrimidine synthase, a member of the radical SAM superfamily. Studies using isotopically labelled AIR have shown which atoms carry into the product. Mechanisms by which this occurs are not yet known with certainty.
In yeasts, HMP-P is derived from metabolites of histidine and pyridoxine. Some of these transformations appear to be catalyzed by radical SAM enzymes. Isotopically labelled precursors have been used to investigate this biogenesis. Mechanisms of the transformations are unknown.
In Salmonella, HMP-P can be derived independently of purine biogenesis when AICAR is available.
In algae, thiamine forms and precursors are scavenged by uptake from water of exogenous products from other organisms. In higher plants, thiamine biogenesis resembles that of bacteria. In some circumstances, thiamine forms and precursors may be obtained through symbiotic relationships with microorganisms in the soil.
Genes relevant for transformations in the biogenesis of HMP-P, HET-P, and TPP have been identified in various organisms and some of the proteins resulting from their expression have been characterized. Biosynthesis of TPP is feedback inhibited through actions of a riboswitch.
Research is ongoing towards understanding biochemistry involved and towards facilitating technologies of socioeconomic value for supply of thiamine in various forms. | 1 | Applied and Interdisciplinary Chemistry |
The synthesis and characterization of the platinum carbonyl dianions [Pt(CO)] (n = 1–10), also known as Chini clusters or more correctly Chini-Longoni clusters, are recognized by the scientific community as the most spectacular result of Chini's work.
Chini clusters follow the general formula of [Pt(CO)], 1 subunits. Although these clusters were first reported in 1969 by Chatt and Booth, their structure were not established until Chini and Longoni's work in 1976.
Chini clusters are based on a planar triangular building block that can be condensed as multiple units forming chains usually anywhere from two to ten units long. The chains are formed by stacking of the planar units, extending through platinum to platinum bonds forming trigonal prismatic clusters. Within a triangular unit, the platinum–platinum bond lengths are 2.65 Å and between units the Pt–Pt bond lengths are 3.05 Å. Cluster structure is easily disrupted by deposition onto surfaces such as carbon or silicon, where the chains are broken, but the triangular subunits remain intact. The tetramer [Pt(CO)] is the most common member of this series of clusters. These clusters undergo reversible redox. They catalyze the hydrogenation of alkenes, ketones, and aldehydes.
Chini clusters can also be converted heterometal clusters and catalyze pH driven redox reactions and transport. First, the Chini clusters are the source of platinum atoms for the mixed metal cluster synthesis. For instance, the reaction [Pt(CO)] with [Ag(PPh)] produces heterometal cluster [PtAg(CO)(PPh)]. Second, the Chini clusters with redox properties act as a catalyst that helps transport sodium ions and electrons in the same direction across a liquid membrane, driven by pH-gradient. The [Pt(CO)] platinum clusters, where n=4 – 6, are reduced by OH:
:(n-1)[Pt(CO)] + 2OH ↔ n[Pt(CO)] + HO + 1/2O | 0 | Theoretical and Fundamental Chemistry |
In structural biology, a heterologous association is a binding mode between the protomers of a protein structure. In a heterologous association, each protomer contributes a different set of residues to the binding interface. In contrast, two protomers form an isologous association when they contribute the same set of residues to the protomer-protomer interface. | 1 | Applied and Interdisciplinary Chemistry |
Escitalopram is among the most effective and well-tolerated antidepressants for the short-term (acute) treatment of major depressive disorder in adults. It is also the safest one to give to children and adolescents.
Controversy existed regarding the effectiveness of escitalopram compared with its predecessor, citalopram. The importance of this issue followed from the greater cost of escitalopram relative to the generic mixture of isomers of citalopram, prior to the expiration of the escitalopram patent in 2012, which led to charges of evergreening. Accordingly, this issue has been examined in at least 10 different systematic reviews and meta analyses. , reviews had concluded (with caveats in some cases) that escitalopram is modestly superior to citalopram in efficacy and tolerability. | 0 | Theoretical and Fundamental Chemistry |
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