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Grasselli Brown has over ninety publications, nine books, and a patent in the field of infrared and Raman spectroscopy.
In 1985, she was selected as one of the Foremost Women of the 20th Century. She is the first woman to be inducted into the Hungarian and Austrian Chemical Societies.
In 2002, Grasselli Brown received the National Ellis Medal of Honor and was selected as an International Scientist of the Year.
In 1991, Grasselli Brown was the first woman to be inducted into the Ohio Science and Technology Hall of Fame. She was inducted into the Ohio Women's Hall of Fame in 1989 and is also a member of the Cleveland International Hall of Fame.
In 2004, Grasselli Brown was chosen to be a part of the book "Ohio 200 years, 200 Women: Ohio's First and Finest."
As of 2013, Jeanette Grasselli Brown donated her papers to the Mahn Center for Archives and Special Collections at her alma mater, Ohio University.
In 2022, a permanent exhibit at the Great Lakes Science Center, entitled "Interactive Periodic Table of Element", was created through a donation by the Northeastern Ohio Science & Engineering Fair, in honor of Dr. Jeanette Grasselli Brown and her husband Dr. Glenn Brown. | 0 | Theoretical and Fundamental Chemistry |
A lunar terrane is a major geological province on the Moon. Three terranes have been identified on the Moon: the Procellarum KREEP Terrane, the Feldspathic Highlands Terrane, and the South Pole–Aitken Terrane. Each terrane has a unique origin, composition, and thermal evolution. | 0 | Theoretical and Fundamental Chemistry |
Potassium humate is used in agriculture as a fertilizer additive to increase the efficiency of fertilizers especially nitrogen- and phosphorus-based fertilizer inputs. Other salts of humic acid are manufactured, mainly sodium humate, which is used in animal health supplements. It also can be used in aquaculture. | 0 | Theoretical and Fundamental Chemistry |
Afterhyperpolarization, or AHP, is the hyperpolarizing phase of a neurons action potential where the cells membrane potential falls below the normal resting potential. This is also commonly referred to as an action potential's undershoot phase. AHPs have been segregated into "fast", "medium", and "slow" components that appear to have distinct ionic mechanisms and durations. While fast and medium AHPs can be generated by single action potentials, slow AHPs generally develop only during trains of multiple action potentials.
During single action potentials, transient depolarization of the membrane opens more voltage-gated K channels than are open in the resting state, many of which do not close immediately when the membrane returns to its normal resting voltage. This can lead to an "undershoot" of the membrane potential to values that are more polarized ("hyperpolarized") than was the original resting membrane potential. Ca-activated K channels that open in response to the influx of Ca during the action potential carry much of the K current as the membrane potential becomes more negative. The K permeability of the membrane is transiently unusually high, driving the membrane voltage V even closer to the K equilibrium voltage E. Hence, hyperpolarization persists until the membrane K permeability returns to its usual value.
Medium and slow AHP currents also occur in neurons. The ionic mechanisms underlying medium and slow AHPs are not yet well understood, but may also involve M current and HCN channels for medium AHPs, and ion-dependent currents and/or ionic pumps for slow AHPs.
The afterhyperpolarized (sAHP) state can be followed by an afterdepolarized state (which is not to be confused with the cardiac afterdepolarization) and can thus set the phase of the subthreshold oscillation of the membrane potential, as reported for the stellate cells of the entorhinal cortex. This mechanism is proposed to be functionally important to maintain the spiking of these neurons at a defined phase of the theta cycle, that, in turn, is thought to contribute to encoding of new memories by the medial temporal lobe of the brain | 0 | Theoretical and Fundamental Chemistry |
Richard "Dick" A. Andersen (November 16, 1942 – June 16, 2019) was a professor of chemistry at the University of California, Berkeley, and faculty senior scientist at the chemical sciences division of Lawrence Berkeley National Laboratory. | 0 | Theoretical and Fundamental Chemistry |
An oxocarbenium ion (or oxacarbenium ion) is a chemical species characterized by a central sp-hybridized carbon, an oxygen substituent, and an overall positive charge that is delocalized between the central carbon and oxygen atoms. An oxocarbenium ion is represented by two limiting resonance structures, one in the form of a carbenium ion with the positive charge on carbon and the other in the form of an oxonium species with the formal charge on oxygen. As a resonance hybrid, the true structure falls between the two. Compared to neutral carbonyl compounds like ketones or esters, the carbenium ion form is a larger contributor to the structure. They are common reactive intermediates in the hydrolysis of glycosidic bonds, and are a commonly used strategy for chemical glycosylation. These ions have since been proposed as reactive intermediates in a wide range of chemical transformations, and have been utilized in the total synthesis of several natural products. In addition, they commonly appear in mechanisms of enzyme-catalyzed biosynthesis and hydrolysis of carbohydrates in nature. Anthocyanins are natural flavylium dyes, which are stabilized oxocarbenium compounds. Anthocyanins are responsible for the colors of a wide variety of common flowers such as pansies and edible plants such as eggplant and blueberry. | 0 | Theoretical and Fundamental Chemistry |
Like other siderophores, petrobactin is secreted by an animal pathogenic bacterium. B. anthracis uses petrobactin to acquire iron from its host. Interestingly, while the 3,4-catecholate ends of petrobactin do not improve iron(III) affinity relative to hydroxamate ends, they speed up iron removal from human diferric transferrin. Petrobactin in its ferric and iron-free forms is bound selectively by YclQ (an isogenic disruption mutant in the transporter encoded by the yclNOPQ operon in Bacillus subtilis), as is petrobactin's precursor protocatechuic acid and the ferric petrobactin photoproduct. The yclNOPQ operon is required for the utlization of petrobactin and yclNOPQ orthologs likely contribute to the pathogenicity of Bacilli. | 1 | Applied and Interdisciplinary Chemistry |
A spectrophotometer built with a high quality double monochromator can produce light of sufficient purity and intensity that the instrument can measure a narrow band of optical attenuation of about one million fold (6 AU, Absorbance Units). | 0 | Theoretical and Fundamental Chemistry |
The mechanism for chloroplast DNA (cpDNA) replication has not been conclusively determined, but two main models have been proposed. Scientists have attempted to observe chloroplast replication via electron microscopy since the 1970s. The results of the microscopy experiments led to the idea that chloroplast DNA replicates using a double displacement loop (D-loop). As the D-loop moves through the circular DNA, it adopts a theta intermediary form, also known as a Cairns replication intermediate, and completes replication with a rolling circle mechanism. Transcription starts at specific points of origin. Multiple replication forks open up, allowing replication machinery to transcribe the DNA. As replication continues, the forks grow and eventually converge. The new cpDNA structures separate, creating daughter cpDNA chromosomes.
In addition to the early microscopy experiments, this model is also supported by the amounts of deamination seen in cpDNA. Deamination occurs when an amino group is lost and is a mutation that often results in base changes. When adenine is deaminated, it becomes hypoxanthine. Hypoxanthine can bind to cytosine, and when the XC base pair is replicated, it becomes a GC (thus, an A → G base change).
In cpDNA, there are several A → G deamination gradients. DNA becomes susceptible to deamination events when it is single stranded. When replication forks form, the strand not being copied is single stranded, and thus at risk for A → G deamination. Therefore, gradients in deamination indicate that replication forks were most likely present and the direction that they initially opened (the highest gradient is most likely nearest the start site because it was single stranded for the longest amount of time). This mechanism is still the leading theory today; however, a second theory suggests that most cpDNA is actually linear and replicates through homologous recombination. It further contends that only a minority of the genetic material is kept in circular chromosomes while the rest is in branched, linear, or other complex structures.
One of competing model for cpDNA replication asserts that most cpDNA is linear and participates in homologous recombination and replication structures similar to the linear and circular DNA structures of bacteriophage T4. It has been established that some plants have linear cpDNA, such as maize, and that more species still contain complex structures that scientists do not yet understand. When the original experiments on cpDNA were performed, scientists did notice linear structures; however, they attributed these linear forms to broken circles. If the branched and complex structures seen in cpDNA experiments are real and not artifacts of concatenated circular DNA or broken circles, then a D-loop mechanism of replication is insufficient to explain how those structures would replicate. At the same time, homologous recombination does not expand the multiple A --> G gradients seen in plastomes. Because of the failure to explain the deamination gradient as well as the numerous plant species that have been shown to have circular cpDNA, the predominant theory continues to hold that most cpDNA is circular and most likely replicates via a D loop mechanism. | 0 | Theoretical and Fundamental Chemistry |
Phenolphthalein's pH sensitivity is exploited in other applications: concrete has naturally high pH due to the calcium hydroxide formed when Portland cement reacts with water. As the concrete reacts with carbon dioxide in the atmosphere, pH decreases to 8.5–9. When a 1% phenolphthalein solution is applied to normal concrete, it turns bright pink. However, if it remains colorless, it shows that the concrete has undergone carbonation. In a similar application, some spackling used to repair holes in drywall contains phenolphthalein. When applied, the basic spackling material retains a pink color; when the spackling has cured by reaction with atmospheric carbon dioxide, the pink color fades. | 0 | Theoretical and Fundamental Chemistry |
In 1768, while serving in New Orleans as governor of Spanish Louisiana, Ulloa married a woman from the high society of Lima, Francisca Melchora Rosa Ramírez de Laredo y Encalada, daughter of the Count of San Javier y Casa Laredo. The couple had six children, among them Francisco Javier de Ulloa who became the Spanish Minister of Marine and the 22nd Captain general of the Navy.
In 1779, Ulloa was promoted to teniente general de la Armada (i.e., vice-admiral). In that same year he participated in the Great Siege of Gibraltar, but failure to prevent the first British relief of Gibraltar led to charges of dereliction of duty against Ulloa and two captains under his command, Pedro de Leyba and Manuel Núñez Gaona. The drawn-out military justice proceedings ended with Ulloa's acquittal. Ulloa was later appointed as chief of operations of the Spanish Navy, a position that he occupied at the time of his death in 1795. | 1 | Applied and Interdisciplinary Chemistry |
Cefradine is distributed in the form of capsules containing 250 mg or 500 mg, as a syrup containing 250 mg/5 ml, or in vials for injection containing 500 mg or 1 g.
It is not approved by the FDA for use in the United States. | 0 | Theoretical and Fundamental Chemistry |
In many applications of Bernoulli's equation, the change in the term is so small compared with the other terms that it can be ignored. For example, in the case of aircraft in flight, the change in height is so small the term can be omitted. This allows the above equation to be presented in the following simplified form:
where is called total pressure, and is dynamic pressure. Many authors refer to the pressure as static pressure to distinguish it from total pressure and dynamic pressure . In Aerodynamics, L.J. Clancy writes: "To distinguish it from the total and dynamic pressures, the actual pressure of the fluid, which is associated not with its motion but with its state, is often referred to as the static pressure, but where the term pressure alone is used it refers to this static pressure."
The simplified form of Bernoulli's equation can be summarized in the following memorable word equation:
Every point in a steadily flowing fluid, regardless of the fluid speed at that point, has its own unique static pressure and dynamic pressure . Their sum is defined to be the total pressure . The significance of Bernoulli's principle can now be summarized as "total pressure is constant in any region free of viscous forces". If the fluid flow is brought to rest at some point, this point is called a stagnation point, and at this point the static pressure is equal to the stagnation pressure.
If the fluid flow is irrotational, the total pressure is uniform and Bernoullis principle can be summarized as "total pressure is constant everywhere in the fluid flow". It is reasonable to assume that irrotational flow exists in any situation where a large body of fluid is flowing past a solid body. Examples are aircraft in flight and ships moving in open bodies of water. However, Bernoullis principle importantly does not apply in the boundary layer such as in flow through long pipes. | 1 | Applied and Interdisciplinary Chemistry |
Typical stages in a U6 snRNA (also termed class III) gene initiation (documented in vertebrates only):
*SNAPc (SNRNA Activating Protein complex; subunits: 1, 2, 3, 4, 5) (also termed PBP and PTF) binds to the PSE (Proximal Sequence Element) centered approximately 55 base pairs upstream of the start site of transcription. This assembly is greatly stimulated by the Pol II transcription factors Oct1 and STAF that bind to an enhancer-like DSE (Distal Sequence Element) at least 200 base pairs upstream of the start site of transcription. These factors and promoter elements are shared between Pol II and Pol III transcription of snRNA genes.
*SNAPc acts to assemble TFIIIB at a TATA box centered 26 base pairs upstream of the start site of transcription. It is the presence of a TATA box that specifies that the snRNA gene is transcribed by Pol III rather than Pol II.
*The TFIIIB for U6 snRNA transcription contains a smaller Brf1 paralogue, Brf2.
*TFIIIB is the transcription factor that assembles Pol III at the start site of transcription. Sequence conservation predicts that TFIIIB containing Brf2 also plays a role in promoter opening. | 1 | Applied and Interdisciplinary Chemistry |
A layered model of homogeneous and isotropic material, can be up-scaled to a transverse isotropic medium, proposed by Backus.
Backus presented an equivalent medium theory, a heterogeneous medium can be replaced by a homogeneous one that predicts wave propagation in the actual medium. Backus showed that layering on a scale much finer than the wavelength has an impact and that a number of isotropic layers can be replaced by a homogeneous transversely isotropic medium that behaves exactly in the same manner as the actual medium under static load in the infinite wavelength limit.
If each layer is described by 5 transversely isotropic parameters , specifying the matrix
The elastic moduli for the effective medium will be
where
denotes the volume weighted average over all layers.
This includes isotropic layers, as the layer is isotropic if , and . | 0 | Theoretical and Fundamental Chemistry |
The analysis in the previous section breaks down when the amplitude of the perturbation is large. The growth then becomes non-linear as the spikes and bubbles of the instability tangle and roll up into vortices. Then, as in the figure, numerical simulation of the full problem is required to describe the system. | 1 | Applied and Interdisciplinary Chemistry |
This technique brings together protein and precipitation solutions without premixing them, but instead, injecting them through either sides of a channel, allowing equilibrium through diffusion. The two solutions come into contact in a reagent chamber, both at their maximum concentrations, initiating spontaneous nucleation. As the system comes into equilibrium, the level of supersaturation decreases, favouring crystal growth. | 0 | Theoretical and Fundamental Chemistry |
Dirk Coster (5 October 1889 – 12 February 1950) was a Dutch physicist. He was a professor of Physics and Meteorology at the University of Groningen.
Coster was born in Amsterdam. On 26 February 1919 he married Lina Maria "Miep" Wijsman, who held a degree in Oriental languages. Eventually, she was one of the first women to obtain a doctorate degree in this field from the University of Leiden. Dirk and Miep had two sons and two daughters (Hendrik, Ada, Els, and Herman). Coster is known as the co-discoverer of hafnium (element 72) in 1923, along with George de Hevesy, by means of X-ray spectroscopic analysis of zirconium ore. The discovery took place in Copenhagen, Denmark. Its name is derived from Hafnia, the Latin name for Copenhagen. | 1 | Applied and Interdisciplinary Chemistry |
Immunomagnetic separation (IMS) is a laboratory tool that can efficiently isolate cells out of body fluid or cultured cells. It can also be used as a method of quantifying the pathogenicity of food, blood or feces. DNA analysis have supported the combined use of both this technique and Polymerase Chain Reaction (PCR). Another laboratory separation tool is the affinity magnetic separation (AMS), which is more suitable for the isolation of prokaryotic cells.
IMS deals with the isolation of cells, proteins, and nucleic acids through the specific capture of biomolecules through the attachment of small-magnetized particles, beads, containing antibodies and lectins. These beads are coated to bind to targeted biomolecules, gently separated and goes through multiple cycles of washing to obtain targeted molecules bound to these super paramagnetic beads, which can differentiate based on strength of magnetic field and targeted molecules, are then eluted to collect supernatant and then are able to determine the concentration of specifically targeted biomolecules. IMS obtains certain concentrations of specific molecules within targeted bacteria.
A mixture of cell population will be put into a magnetic field where cells then are attached to super paramagnetic beads, specific example are Dynabeads (4.5-μm), will remain once excess substrate is removed binding to targeted antigen. Dynabeads consists of iron-containing cores, which is covered by a thin layer of a polymer shell allowing the absorption of biomolecules. The beads are coated with primary antibodies, specific-specific antibodies, lectins, enzymes, or streptavidin; the linkage between magnetized beads coated materials are cleavable DNA linker cell separation from the beads when the culturing of cells is more desirable.
Many of these beads have the same principles of separation; however, the presence and different strength s of magnetic fields requires certain sizes of beads, based on the ramifications of the separation of the cell population. The larger sized beads (>2μm) are the most commonly used range that was produced by Dynal (Dynal [UK] Ltd., Wirral, Mersyside, UK; Dynal, Inc., Lake Success, NY). Where as smaller beads (<100 nm) are mostly used for MACS system that was produced by Miltenyi Biotech (Miltenyi Biotech Ltd., Bisley, Surrey, UK; Miltenyi Biotech Inc., Auburn, CA).
Immunomagnetic separation is used in a variety of scientific fields including molecular biology, microbiology, and immunology. (3) This technique of separation does not only consist of separation of cells within the blood, but can also be used for techniques of separation from primary tumors and in metastases research, through separation into component parts, creating a singular-cell delay, then allowing the suitable antibody to label the cell. In metastasis research this separation technique may become necessary to separate when given a cell population and wanting to isolate tumors cells in tumors, peripheral blood, and bone marrow. | 1 | Applied and Interdisciplinary Chemistry |
The Chemical History of a Candle was the title of a series of six lectures on the chemistry and physics of flames given by Michael Faraday at the Royal Institution in 1848, as part of the series of Christmas lectures for young people founded by Faraday in 1825 and still given there every year.
The lectures described the different zones of combustion in the candle flame and the presence of carbon particles in the luminescent zone. Demonstrations included the production and examination of the properties of hydrogen, oxygen, nitrogen and carbon dioxide gases. An electrolysis cell is demonstrated, first in the electroplating of platinum conductors by dissolved copper, then the production of hydrogen and oxygen gases and their recombination to form water. The properties of water itself are studied, including its expansion while freezing (iron vessels are burst by this expansion), and the relative volume of steam produced when water is vaporized. Techniques for weighing gases on a balance are demonstrated. Atmospheric pressure is described and its effects demonstrated.
Faraday emphasizes that several of the demonstrations and experiments performed in the lectures may be performed by children "at home" and makes several comments regarding proper attention to safety.
The lectures were first printed as a book in 1861.
In 2016, Bill Hammack published a video series of the lectures supplemented by commentary and a companion book. Faraday's ideas are still used as the basis for open teaching about energy in modern primary and secondary schools | 1 | Applied and Interdisciplinary Chemistry |
The major activities of SCI America are two yearly events for the presentation of awards. SCI America presents the Perkin Medal (established 1906), the Chemical Industry Medal, first awarded 1933), and the Gordon E. Moore Medal (first awarded 2004).
The first Perkin Medal was awarded to chemist William Henry Perkin to mark the 50th anniversary of his discovery of the aniline dye mauveine. This anniversary was celebrated internationally as the Perkin Jubilee. SCI America commemorated a visit by Perkin and his family to the United States in the fall of 1906 by inviting 400 guests to a dinner in his honor at Delmonico's and presenting him with the first Perkin Medal. The Perkin Medal is considered the highest honor in applied chemistry to be given to a chemist residing in the United States. It is administered jointly by a committee whose representatives include the chairs or presidents of the ACS, the American Institute of Chemical Engineers, the Science History Institute, and SCI America.
From 1920 to 1932, SCI America awarded the Grasselli Medal, on behalf of the Grasselli Chemical Company, for a paper presenting the most useful suggestions in applied chemistry before the Society. This award was replaced in 1933 by the Chemical Industry Medal, which was given to a person who had made a valuable contribution by applying chemical research in industry.
Since 2004 SCI America has awarded a medal in honor of Gordon E. Moore, for early-career innovation involving the application of chemistry. | 1 | Applied and Interdisciplinary Chemistry |
As Richard Feynman put it, "[water waves] that are easily seen by everyone and which are usually used as an example of waves in elementary courses [...] are the worst possible example [...]; they have all the complications that waves can have." The derivation of the general dispersion relation is therefore quite involved.
and . For gravity, an assumption is made of the density of the fluids being constant (i.e., incompressibility), and likewise (waves are not high enough for gravitation to change appreciably). For surface tension, the deviations from planarity (as measured by derivatives of the surface) are supposed to be small. For common waves both approximations are good enough.
The third contribution involves the kinetic energies of the fluids. It is the most complicated and calls for a hydrodynamic framework. Incompressibility is again involved (which is satisfied if the speed of the waves is much less than the speed of sound in the media), together with the flow being irrotational – the flow is then potential. These are typically also good approximations for common situations.
The resulting equation for the potential (which is Laplace equation) can be solved with the proper boundary conditions. On one hand, the velocity must vanish well below the surface (in the "deep water" case, which is the one we consider, otherwise a more involved result is obtained, see Ocean surface waves.) On the other, its vertical component must match the motion of the surface. This contribution ends up being responsible for the extra outside the parenthesis, which causes all regimes to be dispersive, both at low values of , and high ones (except around the one value at which the two dispersions cancel out.) | 1 | Applied and Interdisciplinary Chemistry |
FAST (Fluorescence-Activating and absorption-Shifting Tag) is a small, genetically-encoded, protein tag which allows for fluorescence reporting of proteins of interest. Unlike natural fluorescent proteins and derivates such as GFP or mCherry, FAST is not fluorescent by itself. It can bind selectively a fluorogenic chromophore derived from 4-hydroxybenzylidene rhodanine (HBR), which is itself non fluorescent unless bound. Once bound, the pair of molecules goes through a unique fluorogen activation mechanism based on two spectroscopic changes, increase of fluorescence quantum yield and absorption red shift, hence providing high labeling selectivity. The FAST-fluorogen reporting system can be used in fluorescence microscopy, flow cytometry and any other fluorometric method to explore the living world: biosensors, protein trafficking.
FAST, a small 14 kDa protein, was engineered from the photoactive yellow protein (PYP) by directed evolution. It was reported for the first time in 2016 by researchers from Ecole normale supérieure de Paris.
__TOC__ | 1 | Applied and Interdisciplinary Chemistry |
HSAB is an acronym for "hard and soft (Lewis) acids and bases". HSAB is widely used in chemistry for explaining the stability of compounds, reaction mechanisms and pathways. It assigns the terms hard or soft, and acid or base to chemical species. Hard applies to species which are small, have high charge states (the charge criterion applies mainly to acids, to a lesser extent to bases), and are weakly polarizable. Soft applies to species which are big, have low charge states and are strongly polarizable.
The theory is used in contexts where a qualitative, rather than quantitative, description would help in understanding the predominant factors which drive chemical properties and reactions. This is especially so in transition metal chemistry, where numerous experiments have been done to determine the relative ordering of ligands and transition metal ions in terms of their hardness and softness.
HSAB theory is also useful in predicting the products of metathesis reactions. In 2005 it was shown that even the sensitivity and performance of explosive materials can be explained on basis of HSAB theory.
Ralph Pearson introduced the HSAB principle in the early 1960s as an attempt to unify inorganic and organic reaction chemistry. | 0 | Theoretical and Fundamental Chemistry |
Pan-assay interference compounds (PAINS) are chemical compounds that often give false positive results in high-throughput screens. PAINS tend to react nonspecifically with numerous biological targets rather than specifically affecting one desired target. A number of disruptive functional groups are shared by many PAINS.
While a number of filters have been proposed and are used in virtual screening and computer-aided drug design, the accuracy of filters with regard to compounds they flag and don't flag has been criticized.
Common PAINS include toxoflavin, isothiazolones, hydroxyphenyl hydrazones, curcumin, phenol-sulfonamides, rhodanines, enones, quinones, and catechols. | 1 | Applied and Interdisciplinary Chemistry |
To perform spectral analysis of a source, monochromatic light at every wavelength would be needed to create a spectrum response of the illuminant. A monochromator is used to sample wavelengths from the source and essentially produce a monochromatic signal. It is essentially a variable filter, selectively separating and transmitting a specific wavelength or band of wavelengths from the full spectrum of measured light and excluding any light that falls outside that region.
A typical monochromator achieves this through the use of entrance and exit slits, collimating and focus optics, and a wavelength-dispersing element such as a diffraction grating or prism. Modern monochromators are manufactured with diffraction gratings, and diffraction gratings are used almost exclusively in spectroradiometric applications. Diffraction gratings are preferable due to their versatility, low attenuation, extensive wavelength range, lower cost, and more constant dispersion. Single or double monochromators can be used depending on application, with double monochromators generally providing more precision due to the additional dispersion and baffling between gratings. | 0 | Theoretical and Fundamental Chemistry |
* Reaction temperature can be raised above the solvent's boiling point as the volume of the laboratory devices is typically small. Typically, non-compressible fluids are used with no gas volume so that the expansion factor as a function of pressure is small.
* Mixing can be achieved within seconds at the smaller scales used in flow chemistry.
* Heat transfer is intensified. Mostly, because the area to volume ratio is large. As a result, endothermic and exothermic reactions can be thermostated easily and consistently. The temperature gradient can be steep, allowing efficient control over reaction time.
* Safety is increased:
** Thermal mass of the system is dominated by the apparatus making thermal runaways unlikely.
** Smaller reaction volume is also considered a safety benefit.
** The reactor operates under steady-state conditions.
* Flow reactions can be automated with far less effort than batch reactions. This allows for unattended operation and experimental planning. By coupling the output of the reactor to a detector system, it is possible to go further and create an automated system which can sequentially investigate a range of possible reaction parameters (varying stoichiometry, residence time and temperature) and therefore explore reaction parameters with little or no intervention.
Typical drivers are higher yields/selectivities, less needed manpower, or a higher safety level.
* Multi step reactions can be arranged in a continuous sequence. This can be especially beneficial if intermediate compounds are unstable, toxic, or sensitive to air since they will exist only momentarily and in very small quantities.
* The position along the flowing stream and reaction time point are directly related to one another. This means that it is possible to arrange the system such that further reagents can be introduced into the flowing reaction stream at a precise time point that is desired.
* It is possible to arrange a flowing system such that purification is coupled with the reaction. There are three primary techniques that are used:
** Solid phase scavenging
** Chromatographic separation
** Liquid/Liquid Extraction
* Reactions that involve reagents containing dissolved gases are easily handled, whereas in batch a pressurized "bomb" reactor would be necessary.
* Multi-phase liquid reactions (e.g. phase transfer catalysis) can be performed in a straightforward way, with high reproducibility over a range of scales and conditions.
* Scale up of a proven reaction can be achieved rapidly with little or no process development work, by either changing the reactor volume or by running several reactors in parallel, provided that flows are recalculated to achieve the same residence times. | 1 | Applied and Interdisciplinary Chemistry |
Lost-wax castingalso called investment casting, precision casting, or cire perdue (; borrowed from French)is the process by which a duplicate sculpture (often a metal, such as silver, gold, brass, or bronze) is cast from an original sculpture. Intricate works can be achieved by this method.
The oldest known examples of this technique are approximately 6,500-year-old (4550–4450 BC) and attributed to gold artefacts found at Bulgaria's Varna Necropolis. A copper amulet from Mehrgarh, Indus Valley civilization, in Pakistan, is dated to circa 4,000 BC. Cast copper objects, found in the Nahal Mishmar hoard in southern Israel, which belong to the Chalcolithic period (4500–3500 BC), are estimated, from carbon-14 dating, to date to circa 3500 BC. Other examples from somewhat later periods are from Mesopotamia in the third millennium BC. Lost-wax casting was widespread in Europe until the 18th century, when a piece-moulding process came to predominate.
The steps used in casting small bronze sculptures are fairly standardized, though the process today varies from foundry to foundry (in modern industrial use, the process is called investment casting). Variations of the process include: "lost mould", which recognizes that materials other than wax can be used (such as tallow, resin, tar, and textile); and "waste wax process" (or "waste mould casting"), because the mould is destroyed to remove the cast item. | 1 | Applied and Interdisciplinary Chemistry |
Several equations to predict the number of calories required by humans have been published from the early 20th–21st centuries. In each of the formulas below:
: P is total heat production at complete rest,
: m is mass (kg),
: h is height (cm),
: a is age (years).
;The original Harris–Benedict equation
Historically, the most notable formula was the Harris–Benedict equation, which was published in 1919:
: for men,
: for women,
The difference in BMR for men and women is mainly due to differences in body mass. For example, a 55-year-old woman weighing and tall would have a BMR of per day.
;The revised Harris–Benedict equation
In 1984, the original Harris–Benedict equations were revised using new data. In comparisons with actual expenditure, the revised equations were found to be more accurate:
: for men,
: for women,
It was the best prediction equation until 1990, when Mifflin et al. introduced the equation:
;The Mifflin St Jeor equation
where s is +5 for males and −161 for females.
According to this formula, the woman in the example above has a BMR of per day.
During the last 100 years, lifestyles have changed, and Frankenfield et al. showed it to be about 5% more accurate.
These formulas are based on body mass, which does not take into account the difference in metabolic activity between lean body mass and body fat. Other formulas exist which take into account lean body mass, two of which are the Katch–McArdle formula and Cunningham formula.
;The Katch–McArdle formula (resting daily energy expenditure)
The Katch–McArdle formula is used to predict resting daily energy expenditure (RDEE).
The Cunningham formula is commonly cited to predict RMR instead of BMR; however, the formulas provided by Katch–McArdle and Cunningham are the same.
where ℓ is the lean body mass (LBM in kg):
where f is the body fat percentage.
According to this formula, if the woman in the example has a body fat percentage of 30%, her resting daily energy expenditure (the authors use the term of basal and resting metabolism interchangeably) would be 1262 kcal per day. | 1 | Applied and Interdisciplinary Chemistry |
The protein encoded by this gene is a member of the STAT protein family. In response to cytokines and growth factors, STAT family members are phosphorylated by the receptor associated kinases, and then form homo- or heterodimers that translocate to the cell nucleus where they act as transcription activators. In response to IFN, this protein forms a complex with STAT1 and IFN regulatory factor family protein p48 (IRF9) and form ISGF-3 (IFN-stimulated gene factor-3), in which this protein acts as a transactivator, but lacks the ability to bind DNA directly. The protein mediates innate antiviral activity. Mutations in this gene result in Immunodeficiency 44. ISGF-3 proceeds the activation of genes via the IFN-stimulated response element (ISRE). ISRE-driven genes include Ly-6C, the double-stranded RNA kinase (PKR), 2´ to 5´ oligoadenylate synthase (OAS), MX and potentially MHC class I. Transcription adaptor P300/CBP (EP300/CREBBP) has been shown to interact specifically with this protein, which is thought to be involved in the process of blocking IFN-alpha response by adenovirus.
STAT2 knockout mice are unresponsive to type I IFN and extremely vulnerable to viral infection. They indicate the loss of the type I IFN autocrine loop and several defects in macrophages and T cell responses. Stat2-/- cells show differences in the biological response to IFN-α. | 1 | Applied and Interdisciplinary Chemistry |
It is sometimes unclear what causes specific HABs as their occurrence in some locations appears to be entirely natural, while in others they appear to be a result of human activities. Furthermore, there are many different species of algae that can form HABs, each with different environmental requirements for optimal growth. The frequency and severity of HABs in some parts of the world have been linked to increased nutrient loading from human activities. In other areas, HABs are a predictable seasonal occurrence resulting from coastal upwelling, a natural result of the movement of certain ocean currents.
The growth of marine phytoplankton (both non-toxic and toxic) is generally limited by the availability of nitrates and phosphates, which can be abundant in coastal upwelling zones as well as in agricultural run-off. The type of nitrates and phosphates available in the system are also a factor, since phytoplankton can grow at different rates depending on the relative abundance of these substances (e.g. ammonia, urea, nitrate ion).
A variety of other nutrient sources can also play an important role in affecting algal bloom formation, including iron, silica or carbon. Coastal water pollution produced by humans (including iron fertilization) and systematic increase in sea water temperature have also been suggested as possible contributing factors in HABs.
Among the causes of algal blooms are:
* Excess nutrients—phosphorus and nitrates—from fertilizers or sewage that are discharged to water bodies (also called nutrient pollution)
* climate change
* thermal pollution from power plants and factories
* low water levels in inland waterways and lakes, which reduces water flow and increases water temperatures
* invasive filter feeders—especially Zebra mussels, Dreissena polymorpha—which preferentially eat non-toxic algae, competitors to harmful algae | 0 | Theoretical and Fundamental Chemistry |
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It is an A-5 size consciousness-raising mind opener, free of technical jargon, on Accessibility for All to built environments to convince decision makers that it is a low cost investment and a Win – Win game of indispensable National importance for everyone. | 0 | Theoretical and Fundamental Chemistry |
In order to understand functional genomics it is important to first define function. In their paper Graur et al. define function in two possible ways. These are "selected effect" and "causal role". The "selected effect" function refers to the function for which a trait (DNA, RNA, protein etc.) is selected for. The "causal role" function refers to the function that a trait is sufficient and necessary for. Functional genomics usually tests the "causal role" definition of function.
The goal of functional genomics is to understand the function of genes or proteins, eventually all components of a genome. The term functional genomics is often used to refer to the many technical approaches to study an organisms genes and proteins, including the "biochemical, cellular, and/or physiological properties of each and every gene product" while some authors include the study of nongenic elements in their definition. Functional genomics may also include studies of natural genetic variation over time (such as an organisms development) or space (such as its body regions), as well as functional disruptions such as mutations.
The promise of functional genomics is to generate and synthesize genomic and proteomic knowledge into an understanding of the dynamic properties of an organism. This could potentially provide a more complete picture of how the genome specifies function compared to studies of single genes. Integration of functional genomics data is often a part of systems biology approaches. | 1 | Applied and Interdisciplinary Chemistry |
Space-based solar power essentially consists of three elements:
# collecting solar energy in space with reflectors or inflatable mirrors onto solar cells or heaters for thermal systems
# wireless power transmission to Earth via microwave or laser
# receiving power on Earth via a rectenna, a microwave antenna
The space-based portion will not need to support itself against gravity (other than relatively weak tidal stresses). It needs no protection from terrestrial wind or weather, but will have to cope with space hazards such as micrometeors and solar flares. Two basic methods of conversion have been studied: photovoltaic (PV) and solar dynamic (SD). Most analyses of SBSP have focused on photovoltaic conversion using solar cells that directly convert sunlight into electricity. Solar dynamic uses mirrors to concentrate light on a boiler. The use of solar dynamic could reduce mass per watt. Wireless power transmission was proposed early on as a means to transfer energy from collection to the Earth's surface, using either microwave or laser radiation at a variety of frequencies. | 0 | Theoretical and Fundamental Chemistry |
In contrast to current commercial fission reactors, hybrid reactors potentially demonstrate what is considered inherently safe behavior because they remain deeply subcritical under all conditions and decay heat removal is possible via passive mechanisms. The fission is driven by neutrons provided by fusion ignition events, and is consequently not self-sustaining. If the fusion process is deliberately shut off or the process is disrupted by a mechanical failure, the fission damps out and stops nearly instantly. This is in contrast to the forced damping in a conventional reactor by means of control rods which absorb neutrons to reduce the neutron flux below the critical, self-sustaining, level. The inherent danger of a conventional fission reactor is any situation leading to a positive feedback, runaway, chain reaction such as occurred during the Chernobyl disaster. In a hybrid configuration the fission and fusion reactions are decoupled, i.e. while the fusion neutron output drives the fission, the fission output has no effect whatsoever on the fusion reaction, eliminating any chance of a positive feedback loop. | 0 | Theoretical and Fundamental Chemistry |
A prill is a small aggregate or globule of a material, most often a dry sphere, formed from a melted liquid through spray crystallization. Prilled is a term used in mining and manufacturing to refer to a product that has been pelletized. ANFO explosive typically comprises ammonium nitrate prills mixed with #2 fuel oil. The pellets are a neater, simpler form for handling, with reduced dust.
The material to be prilled must be in a solid state at room temperature and a low-viscosity liquid when melted. Prills are formed by allowing drops of the melted prill substance to congeal or freeze in mid-air after being dripped from the top of a tall prilling tower. Certain agrochemicals such as urea are often supplied in prilled form. Fertilizers (ammonium nitrate, urea, NPK fertilizer) and some detergent powders are commonly manufactured as prills. However prilling of ammonium nitrate and urea has in recent years been replaced by fluid bed granulation as this gives strong and more abrasion-resistant granules.
Melted material may also be atomized and then allowed to form smaller prills that are useful in cosmetics, food, and animal feed. | 1 | Applied and Interdisciplinary Chemistry |
The shape of the photocyte granules ranges from more round to more elliptical, and there are three types of photocyte granules. The bioluminescent reaction is confined to the granules. The granules range from 0.6 to 2.5 micrometers in the larval photocytes of Photuris pennsylvanica and between 2.5 and 4.5 micrometers in the adult photocytes of the asiatic firefly. The size and shape of photocytes can exhibits a great deal of diversity among the species they are found in. The different types of granules have been observed together within individual photocytes. The illumination of the photocytes is confined to the granules where the reaction occurs. | 1 | Applied and Interdisciplinary Chemistry |
Meropenem is administered intravenously as an aqueous solution. Meropenem is stored in vials as white crystalline powder (containing meropenem as the trihydrate blended with anhydrous sodium carbonate). For intravenous administration, the powder is dissolved in 5% monobasic potassium phosphate solution, since meropenem is soluble in 5% monobasic potassium phosphate solution and only sparingly soluble in water (). For intravenous bolus administration, injection vials are reconstituted with sterile water for injection.
Reconstituted (dissolved) meropenem degrades over time. The degradation may be associated with color change of the solution, typical for a hydrolysis of the amide bond of the β-lactam ring as seen with most β-lactam antibiotics, while particularly for merapenem the color is changing from colorless or pale yellow to vivid yellowish. Upon reconstitution, the merapenem infusion solution, prepared with 0.9% sodium chloride, exhibits both chemical and physical stability for a duration of 3 hours at a temperature up to °C. If refrigerated (°C), the stability extends to 24 hours. However, when the product is reconstituted in a 5% dextrose solution, it is used immediately to ensure its efficacy. The degradation of meropenem in a water-based solution is affected by factors such as pH, temperature, initial concentration, and the specific type of infusion solution used. Meropenem solutions should not be frozen.
Meropenem is administered every 8 hours.
Dosing must be adjusted for altered kidney function and for haemofiltration.
Studies recomment application of meropenem therapeutic drug monitoring for optimal application.
As with other β-lactams antibiotics, the effectiveness of treatment depends on the amount of time during the dosing interval that the meropenem concentration is above the minimum inhibitory concentration for the bacteria causing the infection. For β-lactams, including meropenem, prolonged intravenous administration is associated with lower mortality than bolus intravenous infusion in persons with whose infections are severe, or caused by bacteria that are less sensitive to meropenem, such as Pseudomonas aeruginosa.
Meropenem exhibit poor permeability across the gut and low oral bioavailability because of its hydrophilic properties, which inhibit its passive diffusion across the intestinal epithelium. The challenges related to research of oral delivery of meropenem are related to high susceptibility of meropenem to degradation through hydrolysis of the amide bond in the β-lactam ring, even at relatively low temperatures and humidity. This instability can result in the loss of meropenems antibacterial activity. Besides that, neropenem is unstable in the acidic environment of the stomach, leading to extensive degradation and loss of the drug after oral administration. In addition, intestinal efflux (secretory) transport can pump the drug back into the gut: efflux transporters, particularly P-glycoprotein (P-gp), present in the gastrointestinal tract can actively pump meropenem back into the gut lumen, limiting its absorption and reducing oral bioavailability; in the attempts of oral administration bacteria can develop resistance to meropenem by enhancing the active efflux of the antibiotic through efflux transporters, such as the MexAB-OprM tripartite efflux system in Pseudomonas aeruginosa. Thats why meropenem is administered intravenously.
There is insufficient data regarding the administration of meropenem during breastfeeding. However, it has been observed that, in general, the concentration of this beta-lactam antibiotic in breast milk is relatively low, therefore, beta-lactam antibiotics are not anticipated to induce detrimental effects in infants who are breastfed. Nonetheless, there have been sporadic reports of disturbances in the gastrointestinal flora of the infant, manifesting as diarrhea or oral candidiasis (thrush), associated with the use of beta-lactam antibiotics, however, these potential side effects have not been thoroughly investigated specifically in the context of meropenem use, therefore, the safety profile of meropenem in breastfeeding mothers and their infants is unknown. | 0 | Theoretical and Fundamental Chemistry |
It is important to note that while all non-competitive inhibitors bind the enzyme at allosteric sites (i.e. locations other than its active site)—not all inhibitors that bind at allosteric sites are non-competitive inhibitors. In fact, allosteric inhibitors may act as competitive, non-competitive, or uncompetitive inhibitors.
Many sources continue to conflate these two terms, or state the definition of allosteric inhibition as the definition for non-competitive inhibition. | 1 | Applied and Interdisciplinary Chemistry |
Sub-Doppler cooling is a class of laser cooling techniques that reduce the temperature of atoms and molecules below the Doppler cooling limit. Doppler cooling processes have a cooling limit that is characterized by the momentum recoil from the emission of a photon from the particle.
Some methods of sub-Doppler cooling include optical molasses, Sisyphus cooling, evaporative cooling, free space Raman cooling, Raman side-band cooling, resolved sideband cooling, polarization gradient cooling, and the use of a dark magneto-optical trap.
For example, an optical molasses time-of-flight technique was used to cool sodium (Doppler limit ) to .
Some possible motivations for sub-doppler cooling include cooling to the motional ground state, a requirement for maintaining fidelity during many quantum computation operations. | 0 | Theoretical and Fundamental Chemistry |
Initially, there were dedicated "ecosan conferences" to present and discuss research on ecosan projects:
* A first workshop on ecological sanitation was held in Balingsholm, Sweden in 1997, where all the then established ecosan experts, such as Håkan Jönsson, Peter Morgan (winner of the 2013 Stockholm Water Prize), Ron Sawyer, George Anna Clark and Gunder Edström participated.
* Workshop in Mexico in 1999 with the title "Closing the Loop - Ecological sanitation for food security"
* Ecosan conference in Bonn, Germany in 2000
* First international ecosan conference in Nanning, China in 2001
* Second ecosan conference in Lübeck Germany in 2003
* Third ecosan conference in Durban, South Africa in 2005
* Ecosan conference in Fortaleza, Brazil called "International Conference on Sustainable Sanitation - Water and Food Security for Latin America" in 2007
Since then the ecosan theme has been integrated into other WASH conferences, and separate large ecosan conferences have no longer been organised. | 1 | Applied and Interdisciplinary Chemistry |
The earliest recorded use of the internal standard method dates back to Gouy's flame spectroscopy work in 1877, where he used an internal standard to determine if the excitation in his flame was consistent. His experimental procedure was later reintroduced in the 1940s, when recording flame photometers became readily available. The use of internal standards continued to grow, being applied to a wide range of analytical techniques including nuclear magnetic resonance (NMR) spectroscopy, chromatography, and inductively coupled plasma spectroscopy. | 0 | Theoretical and Fundamental Chemistry |
In the semiconductor industry sputtering is used to etch the target. Sputter etching is chosen in cases where a high degree of etching anisotropy is needed and selectivity is not a concern. One major drawback of this technique is wafer damage and high voltage use. | 0 | Theoretical and Fundamental Chemistry |
As outlined above, the Kidd Process did not use wax on its permanent cathodes. This highlighted disadvantages associated with the use of wax by the Isa Process. Cathode copper consumers applied pressure to producers to remove residual wax from the cathode copper, and the use of wax also created “housekeeping” problems for Isa Process operators.
Consequently, MIM commenced a development program in 1997 aimed at eliminating the use of wax. This resulted in a new process called the Isa 2000 technology, which was able to produce single-sheet cathode (as opposed to the Kidd taco shell cathode) without using wax.
This was achieved by machining a 90° “V”-groove into the bottom edge of the cathode. The groove weakens the structure of the copper growing at the bottom edge of the cathode plate because the copper crystals grow perpendicular to the cathode plate from opposite sides of the groove, causing them to intersect at right angles to each other. A discontinuity in the structure is formed at the intersection that results in a weak zone, along which the copper splits during stripping.
Figure 4 is a microscope view of the cross-section a copper cathode growing at the tip of a cathode plate. The yellow lines show the orientation and direction of crystal growth. | 1 | Applied and Interdisciplinary Chemistry |
In the region close to the minimum of the objective function, , the system approximates to a linear least-squares system, for which
Therefore, the parameter values are (approximately) linear combinations of the observed data values and the errors on the parameters, , can be obtained by error propagation from the observations, , using the linear formula. Let the variance-covariance matrix for the observations be denoted by and that of the parameters by . Then,
When , this simplifies to
In most cases the errors on the observations are un-correlated, so that is diagonal.
If so, each weight should be the reciprocal of the variance of the corresponding observation. For example, in a potentiometric titration, the weight at a titration point, , can be given by
where is the error in electrode potential or pH, is the slope of the titration curve and is the error on added volume.
When unit weights are used (, ) it is implied that the experimental errors are uncorrelated and all equal: , where is known as the variance of an observation of unit weight, and is an identity matrix. In this case is approximated by
where is the minimum value of the objective function and and are the number of data and parameters, respectively.
In all cases, the variance of the parameter is given by and the covariance between parameters and is given by . Standard deviation is the square root of variance. These error estimates reflect only random errors in the measurements. The true uncertainty in the parameters is larger due to the presence of systematic errors—which, by definition, cannot be quantified.
Note that even though the observations may be uncorrelated, the parameters are always correlated. | 0 | Theoretical and Fundamental Chemistry |
Palinstrophy is the curl of the vorticity. It is defined as
where is the vorticity.
Palinstrophy is mainly used in turbulence study, where there is a need to quantify how vorticity is transferred from one direction to the others. It is closely related to enstrophy, the latter being more equivalent to the "power" of vorticity. | 1 | Applied and Interdisciplinary Chemistry |
A simple buffer solution consists of a solution of an acid and a salt of the conjugate base of the acid. For example, the acid may be acetic acid and the salt may be sodium acetate.
The Henderson–Hasselbalch equation relates the pH of a solution containing a mixture of the two components to the acid dissociation constant, K of the acid, and the concentrations of the species in solution.
To derive the equation a number of simplifying assumptions have to be made.
Assumption 1: The acid, HA, is monobasic and dissociates according to the equations
C is the analytical concentration of the acid and C is the concentration the hydrogen ion that has been added to the solution. The self-dissociation of water is ignored. A quantity in square brackets, [X], represents the concentration of the chemical substance X. It is understood that the symbol H stands for the hydrated hydronium ion. K is an acid dissociation constant.
The Henderson–Hasselbalch equation can be applied to a polybasic acid only if its consecutive pK values differ by at least 3. Phosphoric acid is such an acid.
Assumption 2. The self-ionization of water can be ignored.
This assumption is not, strictly speaking, valid with pH values close to 7, half the value of pK, the constant for self-ionization of water. In this case the mass-balance equation for hydrogen should be extended to take account of the self-ionization of water.
However, the term can be omitted to a good approximation.
Assumption 3: The salt MA is completely dissociated in solution. For example, with sodium acetate
the concentration of the sodium ion, [Na] can be ignored. This is a good approximation for 1:1 electrolytes, but not for salts of ions that have a higher charge such as magnesium sulphate, MgSO, that form ion pairs.
Assumption 4: The quotient of activity coefficients, , is a constant under the experimental conditions covered by the calculations.
The thermodynamic equilibrium constant, ,
is a product of a quotient of concentrations and a quotient, , of activity coefficients .
In these expressions, the quantities in square brackets signify the concentration of the undissociated acid, HA, of the hydrogen ion H, and of the anion A; the quantities are the corresponding activity coefficients. If the quotient of activity coefficients can be assumed to be a constant which is independent of concentrations and pH, the dissociation constant, K can be expressed as a quotient of concentrations.
Rearrangement of this expression and taking logarithms provides the Henderson–Hasselbalch equation | 0 | Theoretical and Fundamental Chemistry |
History of the university and its continuing operations as a higher education institution begins 1 July 1900 and covers several stages. | 1 | Applied and Interdisciplinary Chemistry |
The emergence of metallurgy in pre-Columbian Mesoamerica occurred relatively late in the region's history, with distinctive works of metal apparent in West Mexico by roughly 800 CE, and perhaps as early as 600 CE. Metallurgical techniques likely diffused northward from regions in Central or South America via maritime trade routes; recipients of these metallurgical technologies apparently exploited a wide range of material, including alloys of copper-silver, copper-arsenic, copper-tin and copper-arsenic-tin.
Metal items crafted throughout Mesoamerica may be broken into three classes: utilitarian objects, objects used for individual ornamentation, and ceremonial/ritual objects. The latter two categories comprise the bulk of distinctly Mesoamerican artifacts, with metals playing a particularly important role in the sacred and symbolic cultural realms. | 1 | Applied and Interdisciplinary Chemistry |
In molecular biology, the presence of amylase can serve as an additional method of selecting for successful integration of a reporter construct in addition to antibiotic resistance. As reporter genes are flanked by homologous regions of the structural gene for amylase, successful integration will disrupt the amylase gene and prevent starch degradation, which is easily detectable through iodine staining. | 1 | Applied and Interdisciplinary Chemistry |
As previously mentioned, photopharmacology relies on the use of molecular photoswitches being incorporated into the structure of biologically active molecules which allows their potency to be controlled optically. They are introduced into the structure of bioactive compounds via insertion, extension, or bioisosteric replacement. These incorporations can be supported by structural considerations of the molecule or SAR (structure-activity relationship) analysis to determine the optimal position. Some examples of photoswitchable molecules commonly used in photopharmacology are azobenzenes, diarylethenes, and photocages. | 1 | Applied and Interdisciplinary Chemistry |
Operating staff at a power station have several duties. Operators are responsible for the safety of the work crews that frequently do repairs on the mechanical and electrical equipment. They maintain the equipment with periodic inspections and log temperatures, pressures and other important information at regular intervals. Operators are responsible for starting and stopping the generators depending on need. They are able to synchronize and adjust the voltage output of the added generation with the running electrical system, without upsetting the system. They must know the electrical and mechanical systems to troubleshoot problems in the facility and add to the reliability of the facility. Operators must be able to respond to an emergency and know the procedures in place to deal with it. | 1 | Applied and Interdisciplinary Chemistry |
GGT is present in the cell membranes of many tissues, including the kidneys, bile duct, pancreas, gallbladder, spleen, heart, brain, and seminal vesicles. It is involved in the transfer of amino acids across the cellular membrane and leukotriene metabolism. It is also involved in glutathione metabolism by transferring the glutamyl moiety to a variety of acceptor molecules including water, certain L-amino acids, and peptides, leaving the cysteine product to preserve intracellular homeostasis of oxidative stress. This general reaction is:
:(5-L-glutamyl)-peptide + an amino acid peptide + 5-L-glutamyl amino acid | 1 | Applied and Interdisciplinary Chemistry |
Spinlock was founded in 2003 by Dr. Daniel J. Pusiol, a renowned physicist specialized in NMR and NQR, professor at the National University of Córdoba and member of the National Scientific and Technical Research Council (CONICET) of Argentina.
Mr. Pusiol lead a team of young researchers to build Spinlock, manufacturing NMR spectrometers and providing Research and Development services for different industries, engaging on the discovery of new applications for the NMR technology.
Closely related to the National University of Córdoba, Spinlock contributes with the University on projects and receives continuous support in the form of education and consultation with leading scientists.
The organization employs scientist and technical staff from diverse areas: engineering, physics, chemistry and computer sciences.
Spinlock has shared its knowledge in international publications and forums (see Determinación del contenido de ácido oleico en semillas de maní por medio de la resonancia magnética nuclear (RMN)). | 0 | Theoretical and Fundamental Chemistry |
Andesitic magma is an intermediate magma and is approximately evenly dispersed regarding iron, magnesium, calcium, sodium, and potassium. The silica composition of andesitic magma ranges from 55 - 65 wt.%. It forms in temperatures ranging from approximately 1470 °F to 1830 °F. Andesitic magma has an intermediate viscosity and volatiles content. It forms minerals such as plagioclase feldspar, mica, and amphibole. | 0 | Theoretical and Fundamental Chemistry |
* John Christopher Draper (1835–1885)
* Henry Draper (1837–1882)
* Virginia Draper Maury (1839–1885)
* Daniel Draper (1841–1931)
* William Draper (1845–1853)
* Antonia Draper Dixon (1849–1923) | 0 | Theoretical and Fundamental Chemistry |
Early European bloomeries were relatively small, primarily due to the mechanical limits of human-powered bellows and the amount of force possible to apply with hand-driven sledge hammers. Those known archaeologically from the pre-Roman Iron Age tend to be in the 2 kg range, produced in low shaft furnaces. Roman-era production often used furnaces tall enough to create a natural draft effect (into the range of 200 cm tall), and increasing bloom sizes into the range of 10–15 kg. Contemporary experimenters had routinely made blooms using Northern European-derived "short-shaft" furnaces with blown air supplies in the 5–10 kg range The use of waterwheels, spreading around the turn of the first millennium and used to power more massive bellows, allowed the bloomery to become larger and hotter, with associated trip hammers allowing the consolidation forging of the larger blooms created. Progressively larger bloomeries were constructed in the late 14th century, with a capacity of about 15 kg on average, though exceptions did exist. European average bloom sizes quickly rose to 300 kg, where they levelled off until the demise of the bloomery.
As a bloomerys size is increased, the iron ore is exposed to burning charcoal for a longer time. When combined with the strong air blast required to penetrate the large ore and charcoal stack, this may cause part of the iron to melt and become saturated with carbon in the process, producing unforgeable pig iron, which requires oxidation to be reduced into cast iron, steel, and iron. This pig iron was considered a waste product detracting from the largest bloomeries yield, and early blast furnaces, identical in construction, but dedicated to the production of molten iron, were not built until the 14th century.
Bloomery type furnaces typically produced a range of iron products from very low-carbon iron to steel containing around 0.2–1.5% carbon. The master smith had to select pieces of low-carbon iron, carburize them, and pattern-weld them together to make steel sheets. Even when applied to a noncarburized bloom, this pound, fold, and weld process resulted in a more homogeneous product and removed much of the slag. The process had to be repeated up to 15 times when high-quality steel was needed, as for a sword. The alternative was to carburize the surface of a finished product. Each welding's heat oxidises some carbon, so the master smith had to make sure enough carbon was in the starting mixture.
In England and Wales, despite the arrival of the blast furnace in the Weald in about 1491, bloomery forges, probably using waterpower for the hammer and the bellows, were operating in the West Midlands region beyond 1580. In Furness and Cumberland, they operated into the early 17th century and the last one in England (near Garstang) did not close until about 1770.
One of the oldest-known blast furnaces in Europe has been found in Lapphyttan in Sweden, carbon-14 dated to be from the 12th century. The oldest bloomery in Sweden, also found in the same area, has been carbon-14 dated to 700 BCE.
Bloomeries survived in Spain and southern France as Catalan forges into the mid-19th century, and in Austria as the to 1775. | 1 | Applied and Interdisciplinary Chemistry |
Aggressive mimicry through the use of chemicals is used among a wide variety of animals. It functions to either lure the deceived organism to the deceiver or it allows for the organism to accept the presence of a parasite. The chemical mimicry used by parasites allows for the deceived organism to accept the presence of the deceiver while they benefit from either taking up food supplies or directly preying on the host species from within their nest. | 1 | Applied and Interdisciplinary Chemistry |
The Chemical Weapons Act 1996 was passed in the UK during the time of a Conservative government under John Major. It was adopted on the 03/04/1996 and came into force in 16/09/1996. This act was made so that the UK could be compliant with the 1993 Convention on the Prohibition of the Development, Production, Stockpiling and Use of Chemical Weapons and their Destruction. Not only that, but it also creates the criminal offence of producing, developing, handling or transferring chemical weapons. This act gives Britain extra territorial jurisdiction in regard to British nationals who are handling such material. This act also applies to Isle of Man, Guernsey and to Jersey. The department of trade and industry acts as a liaison between the UK and the Organisation for the Prohibition of Chemical Weapons.
The general interpretation of chemical weapons according to this act is as follows:
# "Toxic chemicals and their precursors"
# "Munitions and other devices designed to cause death or harm through the toxic properties of toxic chemicals released by them"
# And finally- "equipment designed for use in connection with munitions and devices falling within paragraph (b)"
Yet there are some exceptions to these rules. For example: the chemical weapons can be used for "peaceful purposes", "purposes related to protection against toxic chemicals", "legitimate military purposes" and "purposes of enforcing the law".
"Legitimate military purposes" are described as being military purposes, which do not cause harm to people, animals or otherwise harm them.
Section 33 of the Chemical Weapon's act requires The secretary of State to prepare a document on the operation of this act and present it to Parliament annually. | 1 | Applied and Interdisciplinary Chemistry |
Several genetic diseases may be the result of splice site mutations. For example, mutations that cause the incorrect splicing of β-globin mRNA are responsible of some cases of β-thalassemia. Another Example is TTP (thrombotic thrombocytopenic purpura). TTP is caused by deficiency of ADAMTS-13. A splice site mutation of ADAMTS-13 gene can therefore cause TTP. It is estimated that 15% of all point mutations causing human genetic diseases occur within a splice site. | 1 | Applied and Interdisciplinary Chemistry |
Environmental UCMs result from highly degraded petroleum hydrocarbons and once formed they can stay largely unchanged in sediments for many years. For example, in 1969 a diesel oil spill contaminated saltmarsh sediment within Wild Harbor River, US; by 1973 only a baseline hump was observed, which remained largely unchanged within the anaerobic sediment for the next 30 years. In a study of the potential for UCM-dominated oil to be further degraded, it was concluded that even using bacteria specifically adapted for complex UCM hydrocarbons in conjunction with nutrient enrichment, biodegradation rates would still be relatively slow. Bacterial degradation of hydrocarbons is complex and will depend on environmental conditions (e.g. aerobic or anaerobic, temperature, nutrient availability, available species of bacteria etc.). | 0 | Theoretical and Fundamental Chemistry |
Hydrogels are created from crosslinked polymers that are water-insoluble. Polymer hydrogels absorb significant amounts of aqueous solutions, and therefore have a high water content. This high water content makes hydrogel more similar to living body tissues than any other material for tissue regeneration. Additionally, polymer scaffolds using self-healing hydrogels are structurally similar to the extracellular matrices of many of the tissues. Scaffolds act as three-dimensional artificial templates in which the tissue targeted for reconstruction is cultured to grow onto. The high porosity of hydrogels allows for the diffusion of cells during migration, as well as the transfer of nutrients and waste products away from cellular membranes. Scaffolds are subject to harsh processing conditions during tissue culturing. These include mechanical stimulation to promote cellular growth, a process which places stress on the scaffold structure. This stress may lead to localized rupturing of the scaffold which is detrimental to the reconstruction process. In a self-healing hydrogel scaffold, ruptured scaffolds have the ability for localized self-repair of their damaged three-dimensional structure.
Current research is exploring the effectiveness of using various types of hydrogel scaffolds for tissue engineering and regeneration including synthetic hydrogels, biological hydrogels, and biohybrid hydrogels.
In 2019, researchers Biplab Sarkar and Vivek Kumar of the New Jersey Institute of Technology developed a self-assembling peptide hydrogel that has proven successful in increasing blood vessel regrowth and neuron survival in rats affected by Traumatic Brain Injuries (TBI). By adapting the hydrogel to closely resemble brain tissue and injecting it into the injured areas of the brain, the researchers’ studies have shown improved mobility and cognition after only a week of treatment. If trials continued to prove successful, this peptide hydrogel may be approved for human trials and eventual widespread use in the medical community as a treatment for TBIs. This hydrogel also has the potential to be adapted to other forms of tissue in the human body, and promote regeneration and recovery from other injuries. | 0 | Theoretical and Fundamental Chemistry |
Gene silencing can be achieved by introducing into cells a short "antisense oligonucleotide" that is complementary to an RNA target. This experiment was first done by Zamecnik and Stephenson in 1978 and continues to be a useful approach, both for laboratory experiments and potentially for clinical applications (antisense therapy). Several viruses, such as influenza viruses Respiratory syncytial virus (RSV) and SARS coronavirus (SARS-CoV), have been targeted using antisense oligonucleotides to inhibit their replication in host cells.
If the antisense oligonucleotide contains a stretch of DNA or a DNA mimic (phosphorothioate DNA, 2′F-ANA, or others) it can recruit RNase H to degrade the target RNA. This makes the mechanism of gene silencing catalytic. Double-stranded RNA can also act as a catalytic, enzyme-dependent antisense agent through the RNAi/siRNA pathway, involving target mRNA recognition through sense-antisense strand pairing followed by target mRNA degradation by the RNA-induced silencing complex (RISC). The R1 plasmid hok/sok system provides yet another example of an enzyme-dependent antisense regulation process through enzymatic degradation of the resulting RNA duplex.
Other antisense mechanisms are not enzyme-dependent, but involve steric blocking of their target RNA (e.g. to prevent translation or to induce alternative splicing). Steric blocking antisense mechanisms often use oligonucleotides that are heavily modified. Since there is no need for RNase H recognition, this can include chemistries such as 2′-O-alkyl, peptide nucleic acid (PNA), locked nucleic acid (LNA), and Morpholino oligomers. | 1 | Applied and Interdisciplinary Chemistry |
In 2023, the Institution launched DiscoverChemEng, an initiative focused on the development of a package of education outreach activities to help inspire future process and chemical engineers and raise awareness of the profession as a career option for young people. A range of resources have been created for IChemE volunteers and STEM ambassadors to use within schools and at careers fairs, alongside an Educator Network that informs volunteers of upcoming events in their local area. | 1 | Applied and Interdisciplinary Chemistry |
Two properties that have a large effect on the functionality of a biomaterial is the surface and bulk properties.
Bulk properties refers to the physical and chemical properties that compose the biomaterial for its entire lifetime. They can be specifically generated to mimic the physiochemical properties of the tissue that the material is replacing. They are mechanical properties that are generated from a material's atomic and molecular construction.
Important bulk properties:
* Chemical Composition
* Microstructure
* Elasticity
* Tensile Strength
* Density
* Hardness
* Electrical Conductivity
* Thermal Conductivity
Surface properties refers to the chemical and topographical features on the surface of the biomaterial that will have direct interaction with the host blood/tissue. Surface engineering and modification allows clinicians to better control the interactions of a biomaterial with the host living system.
Important surface properties:
* Wettability (surface energy)
* Surface chemistry
* Surface textures (smooth/rough)
** Topographical factors including: size, shape, alignment, structure determine the roughness of a material.
* Surface Tension
* Surface Charge | 1 | Applied and Interdisciplinary Chemistry |
The initial cost of the theoretical higher performance compact flange is inevitably higher than a regular flange due to the closer tolerances and significantly more sophisticated design and installation requirements.
By way of example, compact flanges are often used across the following applications: subsea oil and gas or riser, cold work and cryogenics, gas injection, high temperature, and nuclear applications. | 1 | Applied and Interdisciplinary Chemistry |
A solution of the transient convection–diffusion equation can be approximated through a finite difference approach, known as the finite difference method (FDM). | 1 | Applied and Interdisciplinary Chemistry |
These structures, which can be built with rocks or wood (logs or woody debris), gradually lower the elevation of the stream and dissipate flow energy, thereby reducing flow velocity. They can help limit bed degradation. They generate water accumulation upstream from them and fast flowing conditions downstream from them, which can improve fish habitat. However, they can limit fish passage if they are too high. | 1 | Applied and Interdisciplinary Chemistry |
Trisoxazolines baring a benzene backbone have been investigated for molecular recognition and have shown promising selectivity for the recognition of ammonium alkylammonium and sugar species, including examples of chiral recognition. | 0 | Theoretical and Fundamental Chemistry |
Salts of carboxylic acids are named following the usual cation-then-anion conventions used for ionic compounds in both IUPAC and common nomenclature systems. The name of the carboxylate anion () is derived from that of the parent acid by replacing the "–oic acid" ending with "–oate" or "carboxylate." For example, , the sodium salt of benzoic acid (), is called sodium benzoate. Where an acid has both a systematic and a common name (like , for example, which is known as both acetic acid and as ethanoic acid), its salts can be named from either parent name. Thus, can be named as potassium acetate or as potassium ethanoate. The prefix form, is "carboxylato-". | 0 | Theoretical and Fundamental Chemistry |
In organic chemistry, an acetonide is the functional group composed of the cyclic ketal of a diol with acetone. The more systematic name for this structure is an isopropylidene ketal. Acetonide is a common protecting group for 1,2- and 1,3-diols. The protecting group can be removed by hydrolysis of the ketal using dilute aqueous acid. | 0 | Theoretical and Fundamental Chemistry |
The paracrystal model has been useful, for example, in describing the state of partially amorphous semiconductor materials after deposition. It has also been successfully applied to synthetic polymers, liquid crystals, biopolymers, quantum dot solids, and biomembranes. | 0 | Theoretical and Fundamental Chemistry |
A transport coefficient measures how rapidly a perturbed system returns to equilibrium.
The transport coefficients occur in transport phenomenon with transport laws
where:
: is a flux of the property
: the transport coefficient of this property
: , the gradient force which acts on the property .
Transport coefficients can be expressed via a Green–Kubo relation:
where is an observable occurring in a perturbed Hamiltonian, is an ensemble average and the dot above the A denotes the time derivative.
For times that are greater than the correlation time of the fluctuations of the observable the transport coefficient obeys a generalized Einstein relation:
In general a transport coefficient is a tensor. | 0 | Theoretical and Fundamental Chemistry |
Bacterial ADP-ribosylating exotoxins (bAREs) covalently transfer an ADP-ribose moiety of NAD to target proteins of infected eukaryotes, to yield nicotinamide and a free hydrogen ion. bAREs are produced as enzyme precursors, consisting of a "A" and "B" domains: the "A" domain is responsible for ADP-ribosylation activity; and, the "B" domain for translocation of the enzyme across the membrane of the cell. These domains can exist in concert in three forms: first, as single polypeptide chains with A and B domains covalently linked; second, in multi-protein complexes with A and B domains bound by non-covalent interactions; and, third, in multi-protein complexes with A and B domains not directly interacting, prior to processing.
Upon activation, bAREs ADP-ribosylate any number of eukaryotic proteins; such mechanism is crucial to the instigation of the diseased states associated with ADP-ribosylation. GTP-binding proteins, in particular, are well-established in bAREs pathophysiology. For examples, cholera and heat-labile enterotoxin target the α-subunit of Gs of heterotrimeric GTP-binding proteins. As the α-subunit is ADP-ribosylated, it is permanently in an "active", GTP-bound state; subsequent activation of intracellular cyclic AMP stimulates the release of fluid and ions from intestinal epithelial cells. Furthermore, C. Botulinum C3 ADP-ribosylates GTP-binding proteins Rho and Ras, and Pertussis toxin ADP-ribosylates Gi, Go, and Gt. Diphtheria toxin ADP-ribosylates ribosomal elongation factor EF-2, which attenuates protein synthesis.
There are a variety of bacteria which employ bAREs in infection: CARDS toxin of Mycoplasma pneumoniae, cholera toxin of Vibrio cholerae; heat-labile enterotoxin of E. coli; exotoxin A of Pseudomonas aeruginosa; pertussis toxin of B. pertussis; C3 toxin of C. botulinum; and diphtheria toxin of Corynebacterium diphtheriae. | 1 | Applied and Interdisciplinary Chemistry |
Though it was initially dubbed "mysterious protein", recent empirical studies are gradually starting to unveil some of seipins most compelling physiological functions. Among these, the following have been identified: central regulation of energy homeostasis, lipid catabolism (essential for adipocyte differentiation), lipid storage and lipid droplet maintenance, as well as prevention of ectopic lipid droplet formation in non-adipose tissues. Additionally, mutations of BSCL2 have been recently linked to the Silver syndrome (hereditary spastic periplegia type 17) and Celias encephalopathy. | 1 | Applied and Interdisciplinary Chemistry |
Catalytic chain transfer (CCT) is a process that can be incorporated into radical polymerization to obtain greater control over the resulting products. | 0 | Theoretical and Fundamental Chemistry |
The mechanical properties of hydrogels can be fine-tuned in many ways beginning with attention to their hydrophobic properties. Another method of modifying the strength or elasticity of hydrogels is to graft or surface coat them onto a stronger/stiffer support, or by making superporous hydrogel (SPH) composites, in which a cross-linkable matrix swelling additive is added. Other additives, such as nanoparticles and microparticles, have been shown to significantly modify the stiffness and gelation temperature of certain hydrogels used in biomedical applications. | 0 | Theoretical and Fundamental Chemistry |
The Beer-Lambert law is commonly applied to chemical analysis measurements to determine the concentration of chemical species that absorb light. It is often referred to as Beer's law. In physics, the Bouguer–Lambert law is an empirical law which relates the extinction or attenuation of light to the properties of the material through which the light is travelling. It had its first use in astronomical extinction. The fundamental law of extinction (the process is linear in the intensity of radiation and amount of radiatively active matter, provided that the physical state is held constant) is sometimes called the Beer-Bouguer-Lambert law or the Bouguer-Beer-Lambert law or merely the extinction law. The extinction law is also used in understanding attenuation in physical optics, for photons, neutrons, or rarefied gases. In mathematical physics, this law arises as a solution of the BGK equation. | 0 | Theoretical and Fundamental Chemistry |
Consider the reaction
:A ⇌ 2 B + 3 C
Suppose an infinitesimal amount of the reactant A changes into B and C. This requires that all three mole numbers change according to the stoichiometry of the reaction, but they will not change by the same amounts. However, the extent of reaction can be used to describe the changes on a common footing as needed. The change of the number of moles of A can be represented by the equation , the change of B is , and the change of C is .
The change in the extent of reaction is then defined as
where denotes the number of moles of the reactant or product and is the stoichiometric number of the reactant or product. Although less common, we see from this expression that since the stoichiometric number can either be considered to be dimensionless or to have units of moles, conversely the extent of reaction can either be considered to have units of moles or to be a unitless mole fraction.
The extent of reaction represents the amount of progress made towards equilibrium in a chemical reaction. Considering finite changes instead of infinitesimal changes, one can write the equation for the extent of a reaction as
The extent of a reaction is generally defined as zero at the beginning of the reaction. Thus the change of is the extent itself. Assuming that the system has come to equilibrium,
Although in the example above the extent of reaction was positive since the system shifted in the forward direction, this usage implies that in general the extent of reaction can be positive or negative, depending on the direction that the system shifts from its initial composition. | 0 | Theoretical and Fundamental Chemistry |
Off-axis parabolic mirrors are commonly used to collimate and focus THz radiation. Radiation from an effective point source, such as from a low-temperature gallium arsenide (LT-GaAs) antenna (active region ~5 μm) incident on an off-axis parabolic mirror becomes collimated, while collimated radiation incident on a parabolic mirror is focused to a point (see diagram). Terahertz radiation can thus be manipulated spatially using optical components such as metal-coated mirrors as well as lenses made from materials that are transparent at THz wavelengths. Samples for spectroscopy are commonly placed at a focus where the terahertz beam is most concentrated. | 0 | Theoretical and Fundamental Chemistry |
Poly(ADP-ribose)polymerases (PARPs) are found mostly in eukaryotes and catalyze the transfer of multiple ADP-ribose molecules to target proteins. As with mono(ADP-ribosyl)ation, the source of ADP-ribose is NAD. PARPs use a catalytic triad of His-Tyr-Glu to facilitate binding of NAD and positioning of the end of the existing poly(ADP-ribose) chain on the target protein; the Glu facilitates catalysis and formation of a (1→2) O'-glycosidic linkage between two ribose molecules.
There are several other enzymes that recognize poly(ADP-ribose) chains, hydrolyse them or form branches; over 800 proteins have been annotated to contain the loosely defined poly(ADP-ribose) binding motif; therefore, in addition to this modification altering target protein conformation and structure, it may also be used as a tag to recruit other proteins or for regulation of the target protein. | 1 | Applied and Interdisciplinary Chemistry |
Expression of paired receptors is common in many types of leukocytes, especially myeloid cells and natural killer (NK) cells. Activation of NK cells is a complex regulatory process modulated by a number of different paired receptor families coexpressed in this cell type. In some cases, only one member of the pair is expressed in a cell type. Expression of the paired members in a single cell type may vary with time, or the proteins may differ in subcellular localization, resulting in variations in signaling. Expression in NK cells can be stochastic, resulting in unique variations in receptor repertoire.
Some paired receptors are expressed outside the immune system, for example in neurons, endothelium, and epithelium but in many examples, wide tissue distribution can be observed. | 1 | Applied and Interdisciplinary Chemistry |
Organoselenium compounds (or any selenium compound) are cumulative poisons despite the fact that trace amounts of Se are required for health. | 0 | Theoretical and Fundamental Chemistry |
and are normally the temperature and the pressure of the triple point, but the normal melting temperature at atmospheric pressure are also commonly used as reference point because the normal melting point is much more easily accessible. Typically is then set to 0. and are component-specific parameters.
The Simon–Glatzel equation can be viewed as a combination of the Murnaghan equation of state and the Lindemann law, and an alternative form was proposed by J. J. Gilvarry (1956):
where is general at , is pressure derivative at , is Grüneisen ratio, and is the coefficient in Morse potential. | 0 | Theoretical and Fundamental Chemistry |
Poly(3-hydroxybutyrate-co-3-hydroxyvalerate), commonly known as PHBV, is a polyhydroxyalkanoate-type polymer. It is biodegradable, nontoxic, biocompatible plastic produced naturally by bacteria and a good alternative for many non-biodegradable synthetic polymers. It is a thermoplastic linear aliphatic polyester. It is obtained by the copolymerization of 3-hydroxybutanoic acid and 3-hydroxypentanoic acid. PHBV is used in speciality packaging, orthopedic devices and in controlled release of drugs. PHBV undergoes bacterial degradation in the environment. | 1 | Applied and Interdisciplinary Chemistry |
In 1964, Rahman joined the Karachi University as a lecturer in undergraduate chemistry. He remained associated with the Cambridge University between 1969 and 1973, and is presently honorary Life Fellow at the King's College of the Cambridge University. In 1977, he became the co-director of the Hussain Ebrahim Jamal Research Institute of Chemistry at University of Karachi; eventually he was ascended as the Director in 1990. In 1979, Rahman did the post-doctoral research at the University of Tübingen. Upon returning to Pakistan, he joined Karachi University where he lectures and taught chemistry. He was appointed Professor Emeritus at University of Karachi for life.
He carried out important studies on the synthesis of anti-cancer alkaloids present in the plant Catharanthus roseus and analytical studies on organic compounds involving circular dichroism and is generally recognized as bringing a huge positive change in the development of science and technology as well as higher education in Pakistan.
His book entitled "Stereoselective Synthesis in Organic Chemistry" (Springer-Verlag) was termed a monumental contribution in the field by the Nobel Laureate Sir Derek Barton in the foreword of the book written by him. His book entitled "NMR Spectroscopy-Basic Principles" was published by Springer-Verlag and translated into Japanese for use in university courses in Japan The Nobel Laureate Herbert C. Brown applauded the contributions of Rahman in science and technology. | 0 | Theoretical and Fundamental Chemistry |
Trandolapril acts by competitive inhibition of angiotensin converting enzyme (ACE), a key enzyme in the renin–angiotensin system. which plays an important role in regulating blood pressure. | 0 | Theoretical and Fundamental Chemistry |
The pharmaceuticals pass sewage treatment plants. They like estrogen conjugates may cause problems. Drugs of the research were common, present in the aquatic environment and inability to be adequately removed by sewage treatment plants. There were seven different drugs in the research. Dibutyl sebacate and oleic acid formed liquid cores in capsules because they do not diffuse away from capsules and have affinity for drugs. Capsule external diameters were 740 µm and 680 µm and internal diameters were 570 µm and 500 µm. Agitation was 300 rpm. Equilibrium times were 30, 50 and 90 minutes.
Since dibutyl sebacate and oleic acid were different affinity for drugs, they were used concurrently. Four drugs were extracted effectively for 40–50 minutes (at least 50% removed). Extraction rates did not change significantly above 150 rpm. Membrane thickness did not affect the result significantly. On the contrary the capsule size was remarkable for mass transfer. | 0 | Theoretical and Fundamental Chemistry |
Free energies in the presence of small amplitude fluctuations, e.g. in concentration, can be evaluated using an approximation introduced by Ginzburg and Landau to describe magnetic field gradients in superconductors. This approach allows one to approximate the free energy as an expansion in terms of the concentration gradient , a vector. Since free energy is a scalar and we are probing near its minima, the term proportional to is negligible. The lowest order term is the quadratic expression , a scalar. Here is a parameter that controls the free energy cost of variations in concentration .
The Cahn–Hilliard free energy is then
where is the bulk free energy per unit volume of the homogeneous solution, and the integral is over the volume of the system.
We now want to study the stability of the system with respect to small fluctuations in the concentration , for example a sine wave of amplitude and wavevector , for the wavelength of the concentration wave. To be thermodynamically stable, the free energy change due to any small amplitude concentration fluctuation , must be positive.
We may expand about the average composition c as follows:
:and for the perturbation the free energy change is
:when this is integrated over the volume , the gives zero, while . So, then
As , thermodynamic stability requires that the term in brackets be positive. The is always positive but tends to zero at small wavevectors, large wavelengths. Since we are interested in macroscopic fluctuations, , stability requires that the second derivative of the free energy be positive. When it is, there is no spinodal decomposition, but when it is negative, spinodal decomposition will occur. Then fluctuations with wavevectors become spontaneously unstable, where the critical wave number is given by:
:which corresponds to a fluctuations above a critical wavelength | 0 | Theoretical and Fundamental Chemistry |
Crown ethers are ring-like structures composed of several units of ethylene glycol. Because the radius of their pores are similar to that of alkali metal ions, crown ethers are well known for their ability to bind metallic ions. For example, 12-crown-4, 15-crown-5, 18-crown-6, 21-crown-7, and 24-crown-8 interact with potassium, sodium, ammonium, and calcium ions, respectively. Among the aforementioned crown ethers, all the ions have the strongest binding affinity with 18-crown-6 because the size of 18-crown-6 most closely matches that of the ions. Besides ionic species, crown ethers can also bind to neutral molecules, e.g., 1, 2, 3- triazole. Crown ethers can also be threaded with long, linear molecules and/or polymers, giving rise to supramolecular structures called rotaxanes. Given that the crown ethers are not bound to the chains, they can move up and down the threading molecule. | 0 | Theoretical and Fundamental Chemistry |
Due to its involvement in cancer development, inhibition of β-catenin continues to receive significant attention. But the targeting of the binding site on its armadillo domain is not the simplest task, due to its extensive and relatively flat surface. However, for an efficient inhibition, binding to smaller "hotspots" of this surface is sufficient. This way, a "stapled" helical peptide derived from the natural β-catenin binding motif found in LEF1 was sufficient for the complete inhibition of β-catenin dependent transcription. Recently, several small-molecule compounds have also been developed to target the same, highly positively charged area of the ARM domain (CGP049090, PKF118-310, PKF115-584 and ZTM000990). In addition, β-catenin levels can also be influenced by targeting upstream components of the Wnt pathway as well as the β-catenin destruction complex. The additional N-terminal binding pocket is also important for Wnt target gene activation (required for BCL9 recruitment). This site of the ARM domain can be pharmacologically targeted by carnosic acid, for example. That "auxiliary" site is another attractive target for drug development. Despite intensive preclinical research, no β-catenin inhibitors are available as therapeutic agents yet. However, its function can be further examined by siRNA knockdown based on an independent validation. Another therapeutic approach for reducing β-catenin nuclear accumulation is via the inhibition of galectin-3. The galectin-3 inhibitor GR-MD-02 is currently undergoing clinical trials in combination with the FDA-approved dose of ipilimumab in patients who have advanced melanoma. The proteins BCL9 and BCL9L have been proposed as therapeutic targets for colorectal cancers which present hyper-activated Wnt signaling, because their deletion does not perturb normal homeostasis but strongly affects metastases behaviour. | 1 | Applied and Interdisciplinary Chemistry |
In the following years, polymer chemists started studying the characteristics of this polymer and worked on enhancing its thermal stability and mechanical properties. In particular, Moore and coworkers conducted rigorous mechanistic studies on poly(phthalaldehyde) by modifying the type of catalyst used, as well as the starting monomer concentration in an effort to control the molar mass, decrease the polydispersity index, and increase the polymer's purity. Among the catalysts used were triethyloxonium borofluoride, tin chloride, and triphenylmethylium tetrafluoroborate. | 0 | Theoretical and Fundamental Chemistry |
Many medical devices and products come into contact with the internal surfaces of the body, such as surgical tools and implants. When a non-native material enters the body, the first step of the immune response takes place and host extracellular matrix and plasma proteins aggregate to the material in attempts to contain, neutralize, or wall-off the injurious agent. These proteins can facilitate the attachment of various cell types such as osteoblasts and fibroblasts that can encourage tissue repair. Taking this a step further, implantable devices can be coated with a bioactive material to encourage adsorption of specific proteins, fibrous capsule formation, and wound healing. This would reduce the risk of implant rejection and accelerate recovery by selecting for the necessary proteins and cells necessary for endothelialization. After the formation of the endothelium, the body will no longer be exposed to the foreign material, and will stop the immune response.
Proteins such as collagen or fibrin often serve as scaffolds for cell adhesion and cell growth. This is an integral part to the structural integrity of cell sheets and their differentiation into more complex tissue and organ structures. The adhesion properties of proteins to non-biological surfaces greatly influences whether or not cells can indirectly attach to them via scaffolds. An implant like a hip-stem replacement necessitates integration with the host tissues, and protein adsorption facilitates this integration.
Surgical tools can be designed to be sterilized more easily so that proteins do not remain adsorbed to a surface, risking cross-contamination. Some diseases such as Creutzfeldt–Jakob disease and kuru (both related to mad cow disease) are caused by the transmission of prions, which are errant or improperly folded forms of a normally native protein. Surgical tools contaminated with prions require a special method of sterilization to completely eradicate all trace elements of the misfolded protein, as they are resistant to many of the normally used cleansing methods.
However, in some cases, protein adsorption to biomaterials can be an extremely unfavorable event. The adhesion of clotting factors may induce thrombosis, which may lead to stroke or other blockages. Some devices are intended to interact with the internal body environment such as sensors or drug-delivery vehicles, and protein adsorption would hinder their effectiveness. | 1 | Applied and Interdisciplinary Chemistry |
While metals are not necessarily inherently bioactive, bioactive glass coatings which are applied to metal substrates via laser-cladding introduce the bioactivity that the glass would express, but have the added benefits of having a metal base.
Laser Cladding is a method by which bioactive glass microparticles are thrust in a stream at the bulk material, and introduced to a high enough heat that they melt into a coating of material. | 0 | Theoretical and Fundamental Chemistry |
Serial Analysis of Gene Expression (SAGE) is a transcriptomic technique used by molecular biologists to produce a snapshot of the messenger RNA population in a sample of interest in the form of small tags that correspond to fragments of those transcripts. Several variants have been developed since, most notably a more robust version, LongSAGE, RL-SAGE and the most recent SuperSAGE. Many of these have improved the technique with the capture of longer tags, enabling more confident identification of a source gene. | 1 | Applied and Interdisciplinary Chemistry |
Other types of expansion joints can include: fabric expansion joint, metal expansion joint (Pressure balanced expansion joints are a type of Metal expansion joints), toroidal expansion joint, gimbal expansion joint, universal expansion joint, in-line expansion joint, refractory lined expansion joint, hinged expansion joint, reinforced expansion joint and more.
Copper expansion joints are excellent materials designed for the movement of building components due to temperature, loads, and settlement. Copper is easy to form and lasts a long time. Details regarding roof conditions, roof edges, floors, are available. | 1 | Applied and Interdisciplinary Chemistry |
* Chapter 1 - Basic Concepts of Alchemy
* Chapter 2 - The Psychic Nature of Alchemical Work
* Chapter 3 - The Work
* Chapter 4 - The Prima Materia
* Chapter 5 - The Lapis-Christ Parallel
* Chapter 6 - Alchemical Symbolism in the History of Religion | 1 | Applied and Interdisciplinary Chemistry |
Bioswales can be implemented in areas that require stormwater management to regulate the runoff velocity and decontaminate the runoff. Bioswales are created to handle the first flush of pollutants during the event of rain, therefore, locations that have high areas of impervious surface such as roads, parking lots, or rooftops can benefit from additions of bioswales. They can also be integrated into road medians, curb cutouts, sidewalks, or any public space. | 1 | Applied and Interdisciplinary Chemistry |
Surface scientists commonly use an optical goniometer/tensiometer to measure the surface tension and interfacial tension of a liquid using the pendant or sessile drop methods. A drop is produced and captured using a CCD camera. The drop profile is subsequently extracted, and sophisticated software routines then fit the theoretical Young-Laplace equation to the experimental drop profile. The surface tension can then be calculated from the fitted parameters. Unlike other methods, this technique requires only a small amount of liquid making it suitable for measuring interfacial tensions of expensive liquids. | 0 | Theoretical and Fundamental Chemistry |
The citric acid cycle is also called the Krebs cycle or the tricarboxylic acid cycle. When oxygen is present, acetyl-CoA is produced from the pyruvate molecules created from glycolysis. Once acetyl-CoA is formed, aerobic or anaerobic respiration can occur. When oxygen is present, the mitochondria will undergo aerobic respiration which leads to the Krebs cycle. However, if oxygen is not present, fermentation of the pyruvate molecule will occur. In the presence of oxygen, when acetyl-CoA is produced, the molecule then enters the citric acid cycle (Krebs cycle) inside the mitochondrial matrix, and is oxidized to CO while at the same time reducing NAD to NADH. NADH can be used by the electron transport chain to create further ATP as part of oxidative phosphorylation. To fully oxidize the equivalent of one glucose molecule, two acetyl-CoA must be metabolized by the Krebs cycle. Two low-energy waste products, HO and CO, are created during this cycle.
The citric acid cycle is an 8-step process involving 18 different enzymes and co-enzymes. During the cycle, acetyl-CoA (2 carbons) + oxaloacetate (4 carbons) yields citrate (6 carbons), which is rearranged to a more reactive form called isocitrate (6 carbons). Isocitrate is modified to become α-ketoglutarate (5 carbons), succinyl-CoA, succinate, fumarate, malate and, finally, oxaloacetate.
The net gain from one cycle is 3 NADH and 1 FADH as hydrogen- (proton plus electron)-carrying compounds and 1 high-energy GTP, which may subsequently be used to produce ATP. Thus, the total yield from 1 glucose molecule (2 pyruvate molecules) is 6 NADH, 2 FADH, and 2 ATP. | 1 | Applied and Interdisciplinary Chemistry |
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