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Eli Lilly recognized the potential of its new drug, but the company first tested it as a high blood pressure medication, an anti-obesity drug, and a remedy for severe depression. After those testing failures, Eli Lilly succeeded in treating five mildly depressed people; fluoxetine had found its niche. Eli Lilly announced its findings in 1974 and launched Prozac in 1987 after receiving FDA approval.
The “wonder drug” replaced earlier medications, tricyclic antidepressants, which were less effective with serious side effects such as headaches, blurred vision and hypertension. By 1999, Prozac was bringing in $2.5 billion per year, 25% of Eli Lilly's revenue. The drug helped erase the stigma of depression, inspiring celebrities and public figures to flaunt rather than hide their sufferings.
Prozac, which is recognized by Fortune magazine as a “Product of the Century,” has few side effects; it has been widely beneficial for those suffering from depression, obsessive compulsive disorders, panic disorders, eating disorders and premenstrual dysphoric disorders. However, some contend that Prozac has been doled out too liberally—it has even been prescribed for animals. Peer drugs, including Zoloft and Paxil, which are also SSRIs, have experienced similar successes.
Unfortunately for Eli Lilly, its patent on Prozac expired in 2001, causing massive revenue losses. The company hopes to bounce back with its newest drug, Cymbalta, a painkiller and an antidepressant combined. | 0 | Organic Chemistry |
The molecular environment around a supramolecular system is also of prime importance to its operation and stability. Many solvents have strong hydrogen bonding, electrostatic, and charge-transfer capabilities, and are therefore able to become involved in complex equilibria with the system, even breaking complexes completely. For this reason, the choice of solvent can be critical. | 6 | Supramolecular Chemistry |
Acidic protein denaturants include:
* Acetic acid
* Trichloroacetic acid 12% in water
* Sulfosalicylic acid | 1 | Biochemistry |
The technique was invented in 1955 by Grant Henry Lathe and Colin R Ruthven, working at Queen Charlotte's Hospital, London. They later received the John Scott Award for this invention. While Lathe and Ruthven used starch gels as the matrix, Jerker Porath and Per Flodin later introduced dextran gels; other gels with size fractionation properties include agarose and polyacrylamide. A short review of these developments has appeared.
There were also attempts to fractionate synthetic high polymers; however, it was not until 1964, when J. C. Moore of the Dow Chemical Company published his work on the preparation of gel permeation chromatography (GPC) columns based on cross-linked polystyrene with controlled pore size, that a rapid increase of research activity in this field began. It was recognized almost immediately that with proper calibration, GPC was capable to provide molar mass and molar mass distribution information for synthetic polymers. Because the latter information was difficult to obtain by other methods, GPC came rapidly into extensive use. | 1 | Biochemistry |
The Human Metabolome Database (HMDB) is a comprehensive, high-quality, freely accessible, online database of small molecule metabolites found in the human body. It has been created by the Human Metabolome Project funded by Genome Canada and is one of the first dedicated metabolomics databases. The HMDB facilitates human metabolomics research, including the identification and characterization of human metabolites using NMR spectroscopy, GC-MS spectrometry and LC/MS spectrometry. To aid in this discovery process, the HMDB contains three kinds of data: 1) chemical data, 2) clinical data, and 3) molecular biology/biochemistry data (Fig. 1–3). The chemical data includes 41,514 metabolite structures with detailed descriptions along with nearly 10,000 NMR, GC-MS and LC/MS spectra.
The clinical data includes information on >10,000 metabolite-biofluid concentrations and metabolite concentration information on more than 600 different human diseases. The biochemical data includes 5,688 protein (and DNA) sequences and more than 5,000 biochemical reactions that are linked to these metabolite entries. Each metabolite entry in the HMDB contains more than 110 data fields with 2/3 of the information being devoted to chemical/clinical data and the other 1/3 devoted to enzymatic or biochemical data. Many data fields are hyperlinked to other databases (KEGG, MetaCyc, PubChem, Protein Data Bank, ChEBI, Swiss-Prot, and GenBank) and a variety of structure and pathway viewing applets. The HMDB database supports extensive text, sequence, spectral, chemical structure and relational query searches. It has been widely used in metabolomics, clinical chemistry, biomarker discovery and general biochemistry education.
Four additional databases, DrugBank, T3DB, SMPDB and FooDB are also part of the HMDB suite of databases. DrugBank contains equivalent information on ~1,600 drug and drug metabolites, T3DB contains information on 3,100 common toxins and environmental pollutants, SMPDB contains pathway diagrams for 700 human metabolic and disease pathways, while FooDB contains equivalent information on ~28,000 food components and food additives. | 1 | Biochemistry |
RNA is a very similar molecule to DNA, with only two significant chemical differences (the backbone of RNA uses ribose instead of deoxyribose and its nucleobases include uracil instead of thymine). The overall structure of RNA and DNA are immensely similar—one strand of DNA and one of RNA can bind to form a double helical structure. This makes the storage of information in RNA possible in a very similar way to the storage of information in DNA. However, RNA is less stable, being more prone to hydrolysis due to the presence of a hydroxyl group at the ribose 2' position. | 9 | Geochemistry |
Ethers have boiling points similar to those of the analogous alkanes. Simple ethers are generally colorless. | 0 | Organic Chemistry |
It is the standardized method to deal with durability, also known as deem-to-satisfy approach, and provided by current european regulation EN 206. It is required that the designer identifies the environmental exposure conditions and the expected degradation process, assessing the correct exposure class. Once this is defined, design code gives standard prescriptions for w/c ratio, the cement content, and the thickness of the concrete cover.
This approach represents an improvement step for the durability design of reinforced concrete structures, it is suitable for the design of ordinary structures designed with traditional materials (Portland cement, carbon steel rebar) and with an expected service life of 50 years. Nevertheless, it is considered not completely exhaustive in some cases. The simple prescriptions do not allow to optimize the design for different parts of the structures with different local exposure conditions. Furthermore, they do not allow to consider the effects on service life of special measures such as the use of additional protections. | 8 | Metallurgy |
There are many species of bacteria and other microorganisms that live on or inside the healthy human body. In fact, there are roughly as many microbial as human cells in the human body by number.
(much less by mass or volume). Some of these symbionts are necessary for our health. Those that neither help nor harm humans are called commensal organisms. | 1 | Biochemistry |
In 1802, William Hyde Wollaston built a spectrometer, improving on Newtons model, that included a lens to focus the Suns spectrum on a screen. Upon use, Wollaston realized that the colors were not spread uniformly, but instead had missing patches of colors, which appeared as dark bands in the suns spectrum. At the time, Wollaston believed these lines to be natural boundaries between the colors, but this hypothesis was later ruled out in 1815 by Fraunhofers work.
Joseph von Fraunhofer made a significant experimental leap forward by replacing a prism with a diffraction grating as the source of wavelength dispersion. Fraunhofer built off the theories of light interference developed by Thomas Young, François Arago and Augustin-Jean Fresnel. He conducted his own experiments to demonstrate the effect of passing light through a single rectangular slit, two slits, and so forth, eventually developing a means of closely spacing thousands of slits to form a diffraction grating. The interference achieved by a diffraction grating both improves the spectral resolution over a prism and allows for the dispersed wavelengths to be quantified. Fraunhofer's establishment of a quantified wavelength scale paved the way for matching spectra observed in multiple laboratories, from multiple sources (flames and the sun) and with different instruments. Fraunhofer made and published systematic observations of the solar spectrum, and the dark bands he observed and specified the wavelengths of are still known as Fraunhofer lines.
Throughout the early 1800s, a number of scientists pushed the techniques and understanding of spectroscopy forward. In the 1820s, both John Herschel and William H. F. Talbot made systematic observations of salts using flame spectroscopy. | 7 | Physical Chemistry |
Metallography is the study of the physical structure and components of metals, by using microscopy.
Ceramic and polymeric materials may also be prepared using metallographic techniques, hence the terms ceramography, plastography and, collectively, materialography. | 8 | Metallurgy |
Phenylboronic acid or benzeneboronic acid, abbreviated as PhB(OH) where Ph is the phenyl group CH-, is a boronic acid containing a phenyl substituent and two hydroxyl groups attached to boron. Phenylboronic acid is a white powder and is commonly used in organic synthesis. Boronic acids are mild Lewis acids which are generally stable and easy to handle, making them important to organic synthesis. | 0 | Organic Chemistry |
Patients receiving chronic treatment are relatively resistance to nondepolarising NMBAs due to the accelerated clearance. | 1 | Biochemistry |
TGFB1I1 has been shown to interact with:
* Androgen receptor,
* Dopamine transporter
* Hsp27,
* PTK2B,
* PTK2, and
* PTPN12. | 1 | Biochemistry |
A nutrient cycle is the movement and exchange of organic and inorganic matter back into the production of matter. The process is regulated by the pathways available in marine food webs, which ultimately decompose organic matter back into inorganic nutrients. Nutrient cycles occur within ecosystems. Energy flow always follows a unidirectional and noncyclic path, whereas the movement of mineral nutrients is cyclic. Mineral cycles include the carbon cycle, oxygen cycle, nitrogen cycle, phosphorus cycle and sulfur cycle among others that continually recycle along with other mineral nutrients into productive ecological nutrition.
There is considerable overlap between the terms for the biogeochemical cycle and nutrient cycle. Some textbooks integrate the two and seem to treat them as synonymous terms. However, the terms often appear independently. Nutrient cycle is more often used in direct reference to the idea of an intra-system cycle, where an ecosystem functions as a unit. From a practical point, it does not make sense to assess a terrestrial ecosystem by considering the full column of air above it as well as the great depths of Earth below it. While an ecosystem often has no clear boundary, as a working model it is practical to consider the functional community where the bulk of matter and energy transfer occurs. Nutrient cycling occurs in ecosystems that participate in the "larger biogeochemical cycles of the earth through a system of inputs and outputs." | 9 | Geochemistry |
Also well studied are the mesoionic carbenes based on 1,2,3-triazole, referred to as 1,2,3-triazol-4(or 5)-ylidenes. The first triazolylidenes were reported by Albrecht in 2008. These carbenes are typically trisubstituted with alkyl groups in the N1 and N3 positions and an aryl group in the C4 or C5 position. Free carbenes as well as numerous transition metal complexes have been reported. Free carbenes that are alkylated at N3 tend to undergo decomposition reactions in which the alkyl group participates in a nucleophilic attack at the carbene position. If N3 is substituted with a bulky alkyl group or an aryl group, the stability of the carbene increases significantly. | 0 | Organic Chemistry |
These increasing nitrogen and phosphorus nutrient inputs exert eutrophication pressures on coastal zones. These pressures vary geographically depending on the catchment activities and associated nutrient load. The geographical setting of the coastal zone is another important factor as it controls dilution of the nutrient load and oxygen exchange with the atmosphere. The effects of these eutrophication pressures can be seen in several different ways:
# There is evidence from satellite monitoring that the amounts of chlorophyll as a measure of overall phytoplankton activity are increasing in many coastal areas worldwide due to increased nutrient inputs.
# The phytoplankton species composition may change due to increased nutrient loadings and changes in the proportions of key nutrients. In particular the increases in nitrogen and phosphorus inputs, along with much smaller changes in silicon inputs, create changes in the ratio of nitrogen and phosphorus to silicon. These changing nutrient ratios drive changes in phytoplankton species composition, particularly disadvantaging silica rich phytoplankton species like diatoms compared to other species. This process leads to the development of nuisance algal blooms in areas such as the North Sea (see also OSPAR Convention) and the Black Sea. In some cases nutrient enrichment can lead to harmful algal blooms (HABs). Such blooms can occur naturally, but there is good evidence that these are increasing as a result of nutrient enrichment, although the causal linkage between nutrient enrichment and HABs is not straightforward.
# Oxygen depletion has existed in some coastal seas such as the Baltic for thousands of years. In such areas the density structure of the water column severely restricts water column mixing and associated oxygenation of deep water. However, increases in the inputs of bacterially degradable organic matter to such isolated deep waters can exacerbate such oxygen depletion in oceans. These areas of lower dissolved oxygen have increased globally in recent decades. They are usually connected with nutrient enrichment and resulting algal blooms. Climate change will generally tend to increase water column stratification and so exacerbate this oxygen depletion problem. An example of such coastal oxygen depletion is in the Gulf of Mexico where an area of seasonal anoxia more than 5000 square miles in area has developed since the 1950s. The increased primary production driving this anoxia is fueled by nutrients supplied by the Mississippi river. A similar process has been documented in the Black Sea.
# Hypolimnetic oxygen depletion can lead to summer "kills". During summer stratification, inputs or organic matter and sedimentation of primary producers can increase rates of respiration in the hypolimnion. If oxygen depletion becomes extreme, aerobic organisms (such as fish) may die, resulting in what is known as a "summer kill". | 2 | Environmental Chemistry |
Anodized aluminium surfaces that are not regularly cleaned are susceptible to panel edge staining, a unique type of surface staining that can affect the structural integrity of the metal. | 8 | Metallurgy |
The bilirubin level found in the body reflects the balance between production and excretion. Blood test results are advised to always be interpreted using the reference range provided by the laboratory that performed the test. The SI units are μmol/L. Typical ranges for adults are:
* 0–0.3 mg/dl – Direct (conjugated) bilirubin level
* 0.1–1.2 mg/dl – Total serum bilirubin level | 1 | Biochemistry |
Tetra-primer amplification refractory mutation system PCR, or ARMS-PCR, employs two pairs of primers to amplify two alleles in one PCR reaction. The primers are designed such that the two primer pairs overlap at a SNP location but each match perfectly to only one of the possible SNPs. The basis of the invention is that unexpectedly, oligonucleotides with a mismatched 3'-residue will not function as primers in the PCR under appropriate conditions. As a result, if a given allele is present in the PCR reaction, the primer pair specific to that allele will produce product but not to the alternative allele with a different SNP. The two primer pairs are also designed such that their PCR products are of a significantly different length allowing for easily distinguishable bands by gel electrophoresis or melt temperature analysis. In examining the results, if a genomic sample is homozygous, then the PCR products that result will be from the primer that matches the SNP location and the outer opposite-strand primer, as well from the two outer primers. If the genomic sample is heterozygous, then products will result from the primer of each allele and their respective outer primer counterparts as well as the outer primers.
An alternative strategy is to run multiple qPCR reactions with different primer sets that target each allele separately. Well-designed primers will amplify their target SNP at a much earlier cycle than the other SNPs. This allows more than two alleles to be distinguished, although an individual qPCR reaction is required for each SNP. To achieve high enough specificity, the primer sequence may require placement of an artificial mismatch near its 3'-end, which is an approach generally known as Taq-MAMA. | 1 | Biochemistry |
Members of the SOBER1 family are considered closely related to acyl-protein thioesterases, judged by their protein structure. However, a change in their amino acid sequence renders SOBER1's biochemical properties into a deacetylase; in particular the hydrophobic tunnel, which is found in acyl-protein thioesterases, is impaired by additional amino acids in the lid structure of SOBER1, creating a new surface for binding of the acetyl group. | 0 | Organic Chemistry |
The Kelvin probe force microscope or Kelvin force microscope (KFM) is based on an AFM set-up and the determination of the work function is based on the measurement of the electrostatic forces between the small AFM tip and the sample. The conducting tip and the sample are characterized by (in general) different work functions, which represent the difference between the Fermi level and the vacuum level for each material. If both elements were brought in contact, a net electric current would flow between them until the Fermi levels were aligned. The difference between the work functions is called the contact potential difference and is denoted generally with V. An electrostatic force exists between tip and sample, because of the electric field between them. For the measurement a voltage is applied between tip and sample, consisting of a DC-bias V and an AC-voltage V sin(ωt) of frequency ω.
Tuning the AC-frequency to the resonant frequency of the AFM cantilever results in an improved sensitivity. The electrostatic force in a capacitor may be found by differentiating the energy function with respect to the separation of the elements and can be written as
where C is the capacitance, z is the separation, and V is the voltage, each between tip and surface. Substituting the previous formula for voltage (V) shows that the electrostatic force can be split up into three contributions, as the total electrostatic force F acting on the tip then has spectral components at the frequencies ω and 2ω.
The DC component, F, contributes to the topographical signal, the term F at the characteristic frequency ω is used to measure the contact potential and the contribution F can be used for capacitance microscopy. | 7 | Physical Chemistry |
Chemical Geology is an international peer-reviewed academic journal. The journal is affiliated with the European Association of Geochemistry and it is published by Elsevier., publishing both subscription and open access articles. The journal is a hybrid open-access journal.
Chemical Geology publishes original research papers on isotopic and elemental geochemistry, geochronology and cosmochemistry.
The journal focuses on chemical processes in igneous, metamorphic, and sedimentary petrology, low- and high-temperature aqueous solutions, biogeochemistry, the environment and cosmochemistry. | 9 | Geochemistry |
SERS substrates are used to detect the presence of low-abundance biomolecules, and can therefore detect proteins in bodily fluids. Early detection of pancreatic cancer biomarkers was accomplished using SERS-based immunoassay approach. A SERS-base multiplex protein biomarker detection platform in a microfluidic chip is used to detect several protein biomarkers to predict the type of disease and critical biomarkers and increase the chance of differentiating diseases with similar biomarkers like pancreatic cancer, ovarian cancer, and pancreatitis.
This technology has been utilized to detect urea and blood plasma label free in human serum and may become the next generation in cancer detection and screening.
The ability to analyze the composition of a mixture at a nanoscale makes the use of SERS substrates that are beneficial for environmental analysis, pharmaceuticals, material sciences, art and archaeological research, forensic science, drug and explosives detection, food quality analysis, and single algal cell detection.
SERS combined with plasmonic sensing can be used for high-sensitivity quantitative analysis of small molecules in human biofluids, the quantitative detection of biomolecular interaction, the detection of low-level cancer biomarkers via sandwich immunoassay platforms, the label-free characterization of exosomes, and the study of redox processes at a single-molecule level.
SERS is a powerful technique for determining structural information about molecular systems. It has found a wide range of applications in ultra-sensitive chemical sensing and environmental analyses.
A review of the present and future applications of SERS was published in 2020. | 7 | Physical Chemistry |
The light and dark bottle method uses the same concept as the free-water method to estimate rates of metabolism - GPP only occurs during the day with solar energy while ER occurs in both the presence and absence of light. This method incubates lake water in two separate bottles, one that is clear and exposed to natural or artificial light regime and another that is sealed off from the light by wrapping the bottle in foil, paint, or another method. Changes in carbon fixation or dissolved gases are then measured over a certain time period (e.g. several hours to a day) to estimate the rate of metabolism for specific lake depths or an integrated lake water column. Carbon fixation is measured by injecting radioactive carbon isotope C into light and dark bottles and sampling the bottles over the time - the samples are filtered onto filter paper and the amount of C incorporated into algal (and bacterial) cells is estimated by measuring samples on a scintillation counter. The difference between the light and dark bottle C can be considered the rate of primary productivity; however, due to non-photosynthetic uptake of CO there is debate as to whether dark bottles should be used with the C method or if only a light bottle and a bottle treated with the algicide DCMU should be used. Rates of change in dissolved gases, either carbon dioxide or oxygen, need both the light and dark bottles to estimate rates of productivity and respiration. | 1 | Biochemistry |
* Vg1 Family
* Activin Family
** Involved in embryogenesis and osteogenesis
** Regulate insulin and pituitary, gonadal, and hypothalamic hormones
** Nerve cell survival factors
**3 Activins: Activin A, Activin B and Activin AB.
* Glial-Derived Neurotrophic Factor (GDNF)
** Needed for kidney and enteric neuron differentiation
* Müllerian Inhibitory Factor
** Involved in mammalian sex determination
* Nodal
** Binds to Activin A Type 2B receptor
** Forms receptor complex with Activin A Type 1B receptor or with Activin A Type 1C receptor.
*Growth and differentiation factors (GDFs) | 1 | Biochemistry |
In the United States, the Environmental Protection Agency (EPA) is responsible for regulating pesticides under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) and the Food Quality Protection Act (FQPA).
Studies must be conducted to establish the conditions in which the material is safe to use and the effectiveness against the intended pest(s). The EPA regulates pesticides to ensure that these products do not pose adverse effects to humans or the environment, with an emphasis on the health and safety of children. Pesticides produced before November 1984 continue to be reassessed in order to meet the current scientific and regulatory standards. All registered pesticides are reviewed every 15 years to ensure they meet the proper standards. During the registration process, a label is created. The label contains directions for proper use of the material in addition to safety restrictions. Based on acute toxicity, pesticides are assigned to a Toxicity Class. Pesticides are the most thoroughly tested chemicals after drugs in the United States; those used on food require more than 100 tests to determine a range of potential impacts.
Some pesticides are considered too hazardous for sale to the general public and are designated restricted use pesticides. Only certified applicators, who have passed an exam, may purchase or supervise the application of restricted use pesticides. Records of sales and use are required to be maintained and may be audited by government agencies charged with the enforcement of pesticide regulations. These records must be made available to employees and state or territorial environmental regulatory agencies.
In addition to the EPA, the United States Department of Agriculture (USDA) and the United States Food and Drug Administration (FDA) set standards for the level of pesticide residue that is allowed on or in crops. The EPA looks at what the potential human health and environmental effects might be associated with the use of the pesticide.
In addition, the U.S. EPA uses the National Research Council's four-step process for human health risk assessment: (1) Hazard Identification, (2) Dose-Response Assessment, (3) Exposure Assessment, and (4) Risk Characterization.
In 2013 Kauai County (Hawaii) passed Bill No. 2491 to add an article to Chapter 22 of the countys code relating to pesticides and GMOs. The bill strengthens protections of local communities in Kauai where many large pesticide companies test their products.
The first legislation providing federal authority for regulating pesticides was enacted in 1910. | 2 | Environmental Chemistry |
Many explanations fall into this category. First, the secondary orbital interactions theory emphasized that electron-donating heteroatom in the α-position could contribute to increased orbital interaction with the substrate, which stabilizes the transition state (TS) and gives greater reactivity. Second, the electron transfer (ET) mechanism presents that the heteroatom in the α position could stabilize the S2 transition state which has a single electron transfer (free radical) character. Other driving forces including the tighter transition state and higher polarizability of α-nucleophiles, involvement of intramolecular catalysis also plays a role. Another in silico study did find a correlation between the alpha effect and the so-called deformation energy, which is the electronic energy required to bring the two reactants together in the transition state. | 7 | Physical Chemistry |
If irradiated with select projectile nuclei at kinetic energies E, target solid thin-film chemical elements can undergo a nuclear reaction under resonance conditions for a sharply defined resonance energy. The reaction product is usually a nucleus in an excited state which immediately decays, emitting ionizing radiation.
To obtain depth information the initial kinetic energy of the projectile nucleus (which has to exceed the resonance energy) and its stopping power (energy loss per distance traveled) in the sample has to be known. To contribute to the nuclear reaction the projectile nuclei have to slow down in the sample to reach the resonance energy. Thus each initial kinetic energy corresponds to a depth in the sample where the reaction occurs (the higher the energy, the deeper the reaction). | 7 | Physical Chemistry |
In order to see whether p53 re-expression in cancer cells (that have lost p53 expression) has the suppressive effect on the promoter of the survivin gene, a luciferase reporter construct was made. The isolated survivin promoter was placed upstream of the luciferase reporter gene. In a luciferase reporter assay, if the promoter is active, the luciferase gene is transcribed and translated into a product that gives off light that can measured quantitatively and, thus, represents the activity of the promoter. This construct was transfected into cancer cells that had either wild-type or mutant p53. High luciferase activity was measured in the cells with mutant p53 and significantly lower luciferase levels were measured for cells with wild-type p53.
Transfection of different cell types with wild-type p53 was associated with a strong repression of the survivin promoter. Transfection with mutant p53 was not shown to strongly repress the survivin promoter. More luciferase constructs were prepared with varying degrees of deletion from the 5' end of the survivin promoter region. At one point, there was deletion that caused the survivin levels to be indifferent to the presence of the p53 over-expression plasmid, indicating that there is a specific region proximal to the transcription start site that is needed for p53 suppression of survivin. Although it has been found that two p53 binding sites are located on the survivin gene promoter, analysis using deletions and mutations has shown that these sites are not essential to transcriptional inactivation.
Instead, it is observed that modification of the chromatin inside of the promoter region may be responsible for the transcriptional repression of the survivin gene. This is explained below in the epigenetic regulation section. | 1 | Biochemistry |
Because RIP is so efficient at detecting and mutating repeats, fungal biologists often use it as a tool for mutagenesis. A second copy of a single-copy gene is first transformed into the genome. The fungus must then mate and go through its sexual cycle to activate the RIP machinery. Many different mutations within the duplicated gene are obtained from even a single fertilization event so that inactivated alleles, usually due to nonsense mutations, as well as alleles containing missense mutations can be obtained. | 1 | Biochemistry |
In general, the goals of molecular physics experiments are to characterize shape and size, electric and magnetic properties, internal energy levels, and ionization and dissociation energies for molecules. In terms of shape and size, rotational spectra and vibrational spectra allow for the determination of molecular moments of inertia, which allows for calculations of internuclear distances in molecules. X-ray diffraction allows determination of internuclear spacing directly, especially for molecules containing heavy elements. All branches of spectroscopy contribute to determination of molecular energy levels due to the wide range of applicable energies (ultraviolet to microwave regimes). | 7 | Physical Chemistry |
The quadrupole lens consists of two single quadrupoles turned 90° with respect to each other. Let z be the optical axis then one can deduce separately for the x and the y axis that the refractive power is again the square of the refractive power of a single lens.
A magnetic quadrupole works very similar to an electric quadrupole, however the Lorentz force increases with the velocity of the charged particle. In spirit of a Wien filter, a combined magnetic, electric quadrupole is achromatic around a given velocity. Bohr and Pauli claim that this lens leads to aberration when applied to ions with spin (in the sense of chromatic aberration), but not when applied to electrons which also have a spin. See Stern–Gerlach experiment. | 7 | Physical Chemistry |
Peripheral expression of cannabinoid receptors led researchers to investigate the role of cannabinoids in the autonomic nervous system. Research found that the CB receptor is expressed presynaptically by motor neurons that innervate visceral organs. Cannabinoid-mediated inhibition of electric potentials results in a reduction in noradrenaline release from sympathetic nervous system nerves. Other studies have found similar effects in endocannabinoid regulation of intestinal motility, including the innervation of smooth muscles associated with the digestive, urinary, and reproductive systems. | 1 | Biochemistry |
Forests are generally carbon dioxide sinks when they are high in diversity, density or area. However, they can also be carbon sources if diversity, density or area decreases due to deforestation, selective logging, climate change, wildfires or diseases. One study in 2020 found that 32 tracked Brazilian non-Amazon seasonal tropical forests declined from a carbon sink to a carbon source in 2013 and concludes that "policies are needed to mitigate the emission of greenhouse gases and to restore and protect tropical seasonal forests". In 2019 forests took up a third less carbon than they did in the 1990s, due to higher temperatures, droughts and deforestation. The typical tropical forest may become a carbon source by the 2060s.
An assessment of European forests found early signs of carbon sink saturation, after decades of increasing strength. The Intergovernmental Panel on Climate Change (IPCC) concluded that a combination of measures aimed at increasing forest carbon stocks, andsustainable timber offtake will generate the largest carbon sequestration benefit.
Life expectancy of forests varies throughout the world, influenced by tree species, site conditions and natural disturbance patterns. In some forests, carbon may be stored for centuries, while in other forests, carbon is released with frequent stand replacing fires. Forests that are harvested prior to stand replacing events allow for the retention of carbon in manufactured forest products such as lumber. However, only a portion of the carbon removed from logged forests ends up as durable goods and buildings. The remainder ends up as sawmill by-products such as pulp, paper and pallets, which often end with incineration (resulting in carbon release into the atmosphere) at the end of their lifecycle. For instance, of the 1,692 megatonnes of carbon harvested from forests in Oregon and Washington from 1900 to 1992, only 23% is in long-term storage in forest products.
The Food and Agriculure Organization (FAO) reported that: "The total carbon stock in forests decreased from 668 gigatonnes in 1990 to 662 gigatonnes in 2020". However, another study finds that the leaf area index has increased globally since 1981, which was responsible for 12.4% of the accumulated terrestrial carbon sink from 1981 to 2016. The CO fertilization effect, on the other hand, was responsible for 47% of the sink, while climate change reduced the sink by 28.6%. In Canada's boreal forests as much as 80% of the total carbon is stored in the soils as dead organic matter.
Carbon offset programs are planting millions of fast-growing trees per year to reforest tropical lands, for as little as $0.10 per tree. Over their typical 40-year lifetime, one million of these trees can sequester up to one million tons of carbon dioxide. | 5 | Photochemistry |
In its earliest forms, most hardware was simple and hand-made – usually of readily available materials such as wood or leather. A patch of leather spanning between the stile and jamb and fastened with wooden pegs served to hinge a door or shutter. Hand-carved wooden hinges and pintles, slide bolts and lift-latches were whittled from a variety of woods.
The earliest examples of iron hardware were sponsored by the nobility. Iron itself was expensive and a valued resource for any kingdom and had many other more valuable uses in weaponry and tools.
In the post-Renaissance period industrial advances provided more iron and the emerging merchant/tradesman classes had money to purchase hardware for their homes and warehouses. Examples of hardware excavated from the Jamestown and Plymouth colonies of the 17th century were very ornate in design – typical of that being produced in England at the time.
In Colonial America, hardware was made in England and imported to the colonies. It was illegal for the colonials to produce manufactured goods. America sold iron and charcoal to the British, who used those raw materials and their resident labor force to produce hardware which was then sold back to the captive market in the colonies. Virtually all of the early hardware in New York, Philadelphia, Annapolis, Alexandria, Key West, or anyplace else where British ships could berth, was made in England. Away from the ports and cities where British authority was centered, many locally-made examples of early hardware can be found. Examples of German, French, and Dutch hardware remain in the inland river valleys – the homelands of the early settlers. English hardware, however, was the overwhelming standard in colonial America and set the pattern for all that evolved.
Virtually all of the shutters in colonial times were hung with strap hinges – following the examples in Britain. Strap hinges were strong and secure. The frames of windows were hewn from a single heavy piece of wood into which a heavy pintle could be driven. The rails of the shutter were often six or eight inches high and provided room to position the strap hinge across most of the width of the shutter. The hinges were fastened to the shutters with rivets or nails driven through and clinched on the inside of the closed shutter. Locks of the period followed the form of the strap hinges. The rolled barrel was replaced by a pin of about " in diameter and twice the length of the thickness of the shutter mounted perpendicular to the face of the lock. The lock would be nailed or riveted on the lock rail of one shutter with the pin positioned about two inches beyond the edge of the shutter. The opposite shutter would be drilled through with a hole to accept the pin protruding from the lock.
To close and secure the shutter: from the inside close the shutter with the hole then close the shutter with the lock. The lock pin passes through the hole and the user drops a simple nail-like key into the hole in the lock pin. The shutter is virtually impregnable from the exterior.
Tie-backs of the Colonial era were mostly of English origin and many were of the "Rattail" style. Variations are noted as different British manufacturers vied to produce a less expensive product. Inland, where local smiths were producing hardware on their own, a wide range of patterns have been noted. | 8 | Metallurgy |
Since the oceanic intake of carbon dioxide is limited, CO influx can also be described by the Revelle factor. The Revelle Factor is a ratio of the change of carbon dioxide to the change in dissolved inorganic carbon, which serves as an indicator of carbon dioxide dissolution in the mixed layer considering the solubility pump. The Revelle Factor is an expression to characterize the thermodynamic efficiency of the DIC pool to absorb CO into bicarbonate. The lower the Revelle factor, the higher the capacity for ocean water to take in carbon dioxide. While Revelle calculated a factor of around 10 in his day, in a 2004 study data showed a Revelle factor ranging from approximately 9 in low-latitude tropical regions to 15 in the southern ocean near Antarctica. | 9 | Geochemistry |
Bacteria containing the plasmid of interest are first cultured, then a sample is centrifuged in order to concentrate cellular material (including DNA) into a pellet at the bottom of the containing vessel. The supernatant is discarded, and the pellet is then re-suspended in an EDTA-containing physiological buffer. The purpose of the EDTA is to chelate divalent metal cations such as Mg and Ca, which are required for the function of DNA degrading enzymes (DNAses) and also serve to de-stabilise the DNA phosphate backbone and cell wall. Glucose in the buffer will maintain the osmotic pressure of the cell in order to prevent the cell from bursting. Tris in the buffer will retain the pH of the cell with 8.0 and RNase will remove the RNA which will disrupt the experiment.
Separately, a strong alkaline solution consisting of the detergent sodium dodecyl sulfate (SDS) and a strong base such as sodium hydroxide (NaOH) is prepared and then added. The resulting mixture is incubated for a few minutes. During this time, the detergent disrupts cell membranes and allows the alkali to contact and denature both chromosomal and plasmid DNA.
After tearing apart the cell membrane by SDS, the cell content will neutralize the NaOH; this is why the pH of the lysis goes down from 12.8 to 12.3. So if there are not enough bacterial cells, the extra NaOH will function to generate small DNA fragments. But 0.5 M L-arginine, which can supply a stable pH, can be used to replace 0.1 M sodium hydroxide.
Finally, potassium acetate is added. This acidifies the solution and allows the renaturing of plasmid DNA, but not chromosomal DNA, which is precipitated out of solution. Another function of the potassium is to cause the precipitation of sodium dodecyl sulfate and thus removal of the detergent. A final centrifugation is carried out, and this time the pellet contains only debris and can be discarded. The plasmid-containing supernatant is carefully removed and can be further purified or used for analysis, such as gel electrophoresis. | 1 | Biochemistry |
The hCG levels grow exponentially after conception and implantation. hCG levels typically peak around weeks 8-11 of pregnancy and are generally higher in the first trimester compared to the second trimester.
The following is a list of serum hCG levels:
LMP is the last menstrual period dated from the first day of the last menstrual period
If a pregnant woman has serum hCG levels that are higher than expected, they may be experiencing a multiple pregnancy or an abnormal uterine growth. Falling hCG levels may indicate the possibility of a miscarriage. hCG levels which are rising at a slower rate than expected may indicate an ectopic pregnancy. | 1 | Biochemistry |
The introduction of refrigeration allowed for the hygienic handling and storage of perishables, and as such, promoted output growth, consumption, and the availability of nutrition. The change in our method of food preservation moved us away from salts to a more manageable sodium level. The ability to move and store perishables such as meat and dairy led to a 1.7% increase in dairy consumption and overall protein intake by 1.25% annually in the US after the 1890s.
People were not only consuming these perishables because it became easier for they themselves to store them, but because the innovations in refrigerated transportation and storage led to less spoilage and waste, thereby driving the prices of these products down. Refrigeration accounts for at least 5.1% of the increase in adult stature (in the US) through improved nutrition, and when the indirect effects associated with improvements in the quality of nutrients and the reduction in illness is additionally factored in, the overall impact becomes considerably larger. Recent studies have also shown a negative relationship between the number of refrigerators in a household and the rate of gastric cancer mortality. | 7 | Physical Chemistry |
In susceptible persons, beryllium exposure can lead to a cell-mediated immune response. The T-cells become sensitized to beryllium. Each subsequent exposure leads to an immune response involving CD4+ helper T-lymphocytes and macrophages accumulating in the lungs. As this response continues macrophages, CD+4 T-lymphocytes and plasma cells aggregate together to form the noncaseating granulomas. When beryllium is phagocytized by macrophages, the beryllium triggers macrophage apoptosis, thereby reducing beryllium clearance from the lungs and eventually resulting in secondary necrosis and lysis. Eventually, the outcome is fibrosis of the lung.
Several studies have shown that there is a genetic component to beryllium sensitivity. Specifically, those beryllium-exposed workers with a mutation at the HLA-DPB1 Glu position have increased prevalence of beryllium sensitization and chronic beryllium disease. The HLA-DPB1 gene is important for MHC class II molecule function on antigen presenting cells. A study of the immune response to beryllium in individuals who express the HLA-DP2 allele found that CD4 T-cells do not detect the Be+ cation itself, but instead detect surface changes in the HLA-DP2/peptide complex in which Be+ is embedded. Those researchers concluded that chronic beryllium disease is a predisposition that lies between "allergic hypersensitivity and autoimmunity."
According to the International Agency for Research on Cancer, beryllium and beryllium compounds are Category 1 carcinogens; they are carcinogenic to both animals and humans. | 1 | Biochemistry |
In analytical chemistry, sample preparation (working-up) refers to the ways in which a sample is treated prior to its analyses. Preparation is a very important step in most analytical techniques, because the techniques are often not responsive to the analyte in its in-situ form, or the results are distorted by interfering species. Sample preparation may involve dissolution, extraction, reaction with some chemical species, pulverizing, treatment with a chelating agent (e.g. EDTA), masking, filtering, dilution, sub-sampling or many other techniques.
Treatment is done to prepare the sample into a form ready for analysis by specified analytical equipment.
Sample preparation could involve: crushing and dissolution, chemical digestion with acid or alkali, sample extraction, sample clean up and sample pre-concentration. | 3 | Analytical Chemistry |
An oxyanion, or oxoanion, is an ion with the generic formula (where A represents a chemical element and O represents an oxygen atom). Oxyanions are formed by a large majority of the chemical elements. The formulae of simple oxyanions are determined by the octet rule. The corresponding oxyacid of an oxyanion is the compound . The structures of condensed oxyanions can be rationalized in terms of AO polyhedral units with sharing of corners or edges between polyhedra. The oxyanions (specifically, phosphate and polyphosphate esters) adenosine monophosphate (AMP), adenosine diphosphate (ADP) and adenosine triphosphate (ATP) are important in biology. | 7 | Physical Chemistry |
The dative anchoring strategy uses natural amino acid residue in the protein like His, Cys, Glu, Asp and Ser to coordinate to a metal center. Like the first example of Pd-fibroin, dative anchoring is not commonly used now and often resulted in a more ambiguous binding site for metal compared with previous three methods. | 0 | Organic Chemistry |
Dithiofluorescein (sometimes generically called thiofluorescein) is a complexometric indicator used in analytical chemistry. It changes from blue to colorless when it binds to mercury(2+) ions. It thus can indicate the endpoint in the titration of thiols using o-hydroxymercuribenzoic acid or its sodium salt. The reagent can be immobilized t in a polymer on a fiber optic, which might allow development of a detector for sulfide ions in a flow cell. Unlike fluorescein and other related fluoran dyes that have oxygen substituents on the benzene rings, dithiofluorescein, which has sulfur substituents, is not fluorescent. | 3 | Analytical Chemistry |
Thionyl chloride is an inorganic compound with the chemical formula . It is a moderately volatile, colourless liquid with an unpleasant acrid odour. Thionyl chloride is primarily used as a chlorinating reagent, with approximately per year being produced during the early 1990s, but is occasionally also used as a solvent. It is toxic, reacts with water, and is also listed under the Chemical Weapons Convention as it may be used for the production of chemical weapons.
Thionyl chloride is sometimes confused with sulfuryl chloride, , but the properties of these compounds differ significantly. Sulfuryl chloride is a source of chlorine whereas thionyl chloride is a source of chloride ions. | 0 | Organic Chemistry |
Several factors effect the assay outcome and a recent review summarizes the various parameters that needs to be monitored to keep an assay up and running. | 1 | Biochemistry |
Despite the presence of the de novo pathway, the salvage reactions are essential in humans; a lack of niacin in the diet causes the vitamin deficiency disease pellagra. This high requirement for NAD results from the constant consumption of the coenzyme in reactions such as posttranslational modifications, since the cycling of NAD between oxidized and reduced forms in redox reactions does not change the overall levels of the coenzyme.
The major source of NAD in mammals is the salvage pathway which recycles the nicotinamide produced by enzymes utilizing NAD. The first step, and the rate-limiting enzyme in the salvage pathway is nicotinamide phosphoribosyltransferase (NAMPT), which produces nicotinamide mononucleotide (NMN). NMN is the immediate precursor to NAD+ in the salvage pathway.
Besides assembling NAD de novo from simple amino acid precursors, cells also salvage preformed compounds containing a pyridine base. The three vitamin precursors used in these salvage metabolic pathways are nicotinic acid (NA), nicotinamide (Nam) and nicotinamide riboside (NR). These compounds can be taken up from the diet and are termed vitamin B or niacin. However, these compounds are also produced within cells and by digestion of cellular NAD. Some of the enzymes involved in these salvage pathways appear to be concentrated in the cell nucleus, which may compensate for the high level of reactions that consume NAD in this organelle. There are some reports that mammalian cells can take up extracellular NAD from their surroundings, and both nicotinamide and nicotinamide riboside can be absorbed from the gut.
The salvage pathways used in microorganisms differ from those of mammals. Some pathogens, such as the yeast Candida glabrata and the bacterium Haemophilus influenzae are NAD auxotrophs – they cannot synthesize NAD – but possess salvage pathways and thus are dependent on external sources of NAD or its precursors. Even more surprising is the intracellular pathogen Chlamydia trachomatis, which lacks recognizable candidates for any genes involved in the biosynthesis or salvage of both NAD and NADP, and must acquire these coenzymes from its host. | 5 | Photochemistry |
G proteins contain an alpha-subunit that is critical to the functioning of receptors. These subunits can take a number of forms. There are four broad classes of form of G-protein: G, G, G, and G. Muscarinic receptors vary in the G protein to which they are bound, with some correlation according to receptor type. G proteins are also classified according to their susceptibility to cholera toxin (CTX) and pertussis toxin (PTX, whooping cough). G and some subtypes of G (G and G) are susceptible to CTX. Only G is susceptible to PTX, with the exception of one subtype of G (G) which is immune. Also, only when bound with an agonist, those G proteins normally sensitive to PTX also become susceptible to CTX.
The various G-protein subunits act differently upon secondary messengers, upregulating Phospholipases, downregulating cAMP, and so on.
Because of the strong correlations to muscarinic receptor type, CTX and PTX are useful experimental tools in investigating these receptors. | 1 | Biochemistry |
A flow-through detector is located downstream from the sample injector and records a chemical physical parameter. Many types of detector can be used such as:
*spectrophotometer
*fluorimeter
* ion-selective electrode
* biosensors
*mass spectrometer | 3 | Analytical Chemistry |
Mixed valence complexes contain an element which is present in more than one oxidation state. Well-known mixed valence compounds include the Creutz–Taube complex, Prussian blue, and molybdenum blue. Many solids are mixed-valency including indium chalcogenides. | 7 | Physical Chemistry |
The asymmetric atom is called a chirality center, a type of stereocenter. A chirality center is also called a chiral center or an asymmetric center. Some sources use the terms stereocenter, stereogenic center, stereogenic atom or stereogen to refer exclusively to a chirality center, while others use the terms more broadly to refer also to centers that result in diastereomers (stereoisomers that are not enantiomers).
Compounds that contain exactly one (or any odd number) of asymmetric atoms are always chiral. However, compounds that contain an even number of asymmetric atoms sometimes lack chirality because they are arranged in mirror-symmetric pairs, and are known as meso compounds. For instance, meso tartaric acid (shown on the right) has two asymmetric carbon atoms, but it does not exhibit enantiomerism because there is a mirror symmetry plane. Conversely, there exist forms of chirality that do not require asymmetric atoms, such as axial, planar, and helical chirality.
Even though a chiral molecule lacks reflection (C) and rotoreflection symmetries (S), it can have other molecular symmetries, and its symmetry is described by one of the chiral point groups: C, D, T, O, or I. For example, hydrogen peroxide is chiral and has C (two-fold rotational) symmetry. A common chiral case is the point group C, meaning no symmetries, which is the case for lactic acid. | 4 | Stereochemistry |
In excitotoxicity, nerve cells suffer damage or death when the levels of otherwise necessary and safe neurotransmitters such as glutamate become pathologically high, resulting in excessive stimulation of receptors. For example, when glutamate receptors such as the NMDA receptor or AMPA receptor encounter excessive levels of the excitatory neurotransmitter, glutamate, significant neuronal damage might ensue. Excess glutamate allows high levels of calcium ions (Ca) to enter the cell. Ca influx into cells activates a number of enzymes, including phospholipases, endonucleases, and proteases such as calpain. These enzymes go on to damage cell structures such as components of the cytoskeleton, membrane, and DNA. In evolved, complex adaptive systems such as biological life it must be understood that mechanisms are rarely, if ever, simplistically direct. For example, NMDA in subtoxic amounts induces neuronal survival of otherwise toxic levels of glutamate.
Excitotoxicity may be involved in cancers, spinal cord injury, stroke, traumatic brain injury, hearing loss (through noise overexposure or ototoxicity), and in neurodegenerative diseases of the central nervous system such as multiple sclerosis, Alzheimers disease, amyotrophic lateral sclerosis (ALS), Parkinsons disease, alcoholism, alcohol withdrawal or hyperammonemia and especially over-rapid benzodiazepine withdrawal, and also Huntington's disease. Other common conditions that cause excessive glutamate concentrations around neurons are hypoglycemia. Blood sugars are the primary glutamate removal method from inter-synaptic spaces at the NMDA and AMPA receptor site. Persons in excitotoxic shock must never fall into hypoglycemia. Patients should be given 5% glucose (dextrose) IV drip during excitotoxic shock to avoid a dangerous build up of glutamate around NMDA and AMPA neurons. When 5% glucose (dextrose) IV drip is not available high levels of fructose are given orally. Treatment is administered during the acute stages of excitotoxic shock along with glutamate antagonists. Dehydration should be avoided as this also contributes to the concentrations of glutamate in the inter-synaptic cleft and "status epilepticus can also be triggered by a build up of glutamate around inter-synaptic neurons." | 1 | Biochemistry |
Acid sulfate soils are naturally occurring soils, sediments or organic substrates (e.g. peat) that are formed under waterlogged conditions. These soils contain iron sulfide minerals (predominantly as the mineral pyrite) and/or their oxidation products. In an undisturbed state below the water table, acid sulfate soils are benign. However, if the soils are drained, excavated or otherwise exposed to air, the sulfides react with oxygen to form sulfuric acid.
Release of this sulfuric acid from the soil can in turn release iron, aluminium, and other heavy metals and metalloids (particularly arsenic) within the soil. Once mobilized in this way, the acid and metals can create a variety of adverse impacts: killing vegetation, seeping into and acidifying groundwater and surface water bodies, killing fish and other aquatic organisms, and degrading concrete and steel structures to the point of failure. | 9 | Geochemistry |
Service valve is a ball type used to block fluid while replacing corrosion coupons or probes despite fluid flow. The service valve is attached to solid or hollow plug after removing of access fitting cover. It blocks the fluid while the coupon or probe is retrieved by retriever and passed through it. | 8 | Metallurgy |
SMRT (silencing mediator of retinoic acid and thyroid hormone receptor), also known as NCoR2, is an alternatively spliced SRC-1(steroid receptor coactivator-1). It is negatively and positively affected by MAPKKK (mitogen activated protein kinase kinase kinase) and casein kinase 2 phosphorylation, respectively. SMRT has two major mechanisms: first, similar to NCoR, SMRT also recruits class I histone deacetylases through SIN3 and directly binds to class II histone deacetylases. Second, it binds and sequesters components of the general transcriptional machinery, such as transcription factor II B. | 1 | Biochemistry |
In molecular genetics, a repressor is a DNA- or RNA-binding protein that inhibits the expression of one or more genes by binding to the operator or associated silencers. A DNA-binding repressor blocks the attachment of RNA polymerase to the promoter, thus preventing transcription of the genes into messenger RNA. An RNA-binding repressor binds to the mRNA and prevents translation of the mRNA into protein. This blocking or reducing of expression is called repression. | 1 | Biochemistry |
In the assembly of integrated circuit packages to printed circuit boards, a head-in-pillow defect (HIP or HNP), also called ball-and-socket, is a failure of the soldering process. For example, in the case of a ball grid array (BGA) package, the pre-deposited solder ball on the package and the solder paste applied to the circuit board may both melt, but the melted solder does not join. A cross-section through the failed joint shows a distinct boundary between the solder ball on the part and the solder paste on the circuit board, rather like a section through a head resting on a pillow.
The defect can be caused by surface oxidation or poor wetting of the solder, or by distortion of the integrated circuit package or circuit board by the heat of the soldering process. This is particularly a concern when using lead-free solder, which requires higher processing temperature.
The defect can be attributed to a chain of events during soldering. Initially, the ball is in contact with solder paste. During heating, the board and components undergo thermal expansion, can flex, and some of the balls can be lifted off the paste. Oxidation occurs rapidly at elevated temperature, and when the surfaces come in contact again, the residual flux activity may not be sufficient to disrupt the oxide layer. The solder paste composition, eg. flux with higher activation temperature, together with the wetting characteristics of the solder ball, are the most significant mitigation factors.
Since the warping of the circuit board or integrated circuit may disappear when the board cools, an intermittent fault may be created. Diagnosis of head-in-pillow defects may require use of X-rays or EOTPR (Electro Optical Terahertz Pulse Reflectometry), since the solder joints are hidden between the integrated circuit package and the printed circuit board. | 8 | Metallurgy |
Fluorine-18 is usually produced by irradiation of O-enriched water (HO) with high-energy (about 18 MeV) protons prepared in a cyclotron or a linear accelerator, yielding an aqueous solution of F fluoride. This solution is then used for rapid synthesis of a labeled molecule, often with the fluorine atom replacing a hydroxyl group. The labeled molecules or radiopharmaceuticals have to be synthesized after the radiofluorine is prepared, as the high energy proton radiation would destroy the molecules.
Large amounts of oxygen-18 enriched water are used in positron emission tomography centers, for on-site production of F-labeled fludeoxyglucose (FDG).
An example of the production cycle is a 90-minute irradiation of 2 milliliters of O-enriched water in a titanium cell, through a 25 μm thick window made of Havar (a cobalt alloy) foil, with a proton beam having an energy of 17.5 MeV and a beam current of 30 microamperes.
The irradiated water has to be purified before another irradiation, to remove organic contaminants, traces of tritium produced by a O(p,t)O reaction, and ions leached from the target cell and sputtered from the Havar foil. | 9 | Geochemistry |
An organoberyllium carbene consists of a carbene attached to beryllium. The types of carbene includes a N-heterocyclic carbenes (NHC) and cyclic alkyl amino carbenes (CAAC). | 0 | Organic Chemistry |
The inelastic mean free path (IMFP) is an index of how far an electron on average travels through a solid before losing energy.
If a monochromatic, primary beam of electrons is incident on a solid surface, the majority of incident electrons lose their energy because they interact strongly with matter, leading to plasmon excitation, electron-hole pair formation, and vibrational excitation. The intensity of the primary electrons, , is damped as a function of the distance, , into the solid. The intensity decay can be expressed as follows:
where is the intensity after the primary electron beam has traveled through the solid to a distance . The parameter , termed the inelastic mean free path (IMFP), is defined as the distance an electron beam can travel before its intensity decays to of its initial value. (Note that this is equation is closely related to the Beer–Lambert law.)
The inelastic mean free path of electrons can roughly be described by a universal curve that is the same for all materials.
The knowledge of the IMFP is indispensable for several electron spectroscopy and microscopy measurements. | 7 | Physical Chemistry |
Three alternative explanations for the thermalization of isolated quantum systems are often proposed:
# For initial states of physical interest, the coefficients exhibit large fluctuations from eigenstate to eigenstate, in a fashion which is completely uncorrelated with the fluctuations of from eigenstate to eigenstate. Because the coefficients and matrix elements are uncorrelated, the summation in the diagonal ensemble is effectively performing an unbiased sampling of the values of over the appropriate energy window. For a sufficiently large system, this unbiased sampling should result in a value which is close to the true mean of the values of over this window, and will effectively reproduce the prediction of the microcanonical ensemble. However, this mechanism may be disfavored for the following heuristic reason. Typically, one is interested in physical situations in which the initial expectation value of is far from its equilibrium value. For this to be true, the initial state must contain some sort of specific information about , and so it becomes suspect whether or not the initial state truly represents an unbiased sampling of the values of over the appropriate energy window. Furthermore, whether or not this were to be true, it still does not provide an answer to the question of when arbitrary initial states will come to equilibrium, if they ever do.
# For initial states of physical interest, the coefficients are effectively constant, and do not fluctuate at all. In this case, the diagonal ensemble is precisely the same as the microcanonical ensemble, and there is no mystery as to why their predictions are identical. However, this explanation is disfavored for much the same reasons as the first.
# Integrable quantum systems are proved to thermalize under condition of simple regular time-dependence of parameters, suggesting that cosmological expansion of the Universe and integrability of the most fundamental equations of motion are ultimately responsible for thermalization. | 7 | Physical Chemistry |
The second solar spectrum is an electromagnetic spectrum of the Sun that shows the degree of linear polarization. The term was coined by V. V. Ivanov in 1991. The polarization is at a maximum close to the limb (edge) of the Sun, thus the best place to observe such a spectrum is from just inside the limb. It is also possible to get polarized light from outside the limb, but since this is much dimmer compared to the disk of the Sun, it is very easily polluted by scattered light.
The second solar spectrum differs significantly from the solar spectrum determined by the intensity of light.
Large effects come around the Ca II K and H line. These have broad effects 200 Å wide and show a sign reversal at their centers. Molecular lines with stronger polarization than the background due to MgH and C are common. Rare-earth elements stand out far more than expected from the intensity spectrum.
Other odd lines include Li I at 6708 Å which has 0.005% more polarization at its peak, but is almost unobservable in the intensity spectrum. The Ba II 4554 Å appears as a triplet in the second solar spectrum. This is due to differing isotopes and hyperfine structure.
Two lines at 5896 Å 4934 Å being the D lines of sodium and barium were predicted not to be polarized, but nevertheless are present in this spectrum. | 7 | Physical Chemistry |
The term can also refer to octahedral influenced by the Jahn–Teller effect, which is a common phenomenon encountered in coordination chemistry. This reduces the symmetry of the molecule from O to D and is known as a tetragonal distortion. | 4 | Stereochemistry |
Transcription factories, in genetics describe the discrete sites where transcription occurs in the cell nucleus, and are an example of a biomolecular condensate. They were first discovered in 1993 and have been found to have structures analogous to replication factories, sites where replication also occurs in discrete sites. The factories contain an RNA polymerase (active or inactive) and the necessary transcription factors (activators and repressors) for transcription. Transcription factories containing RNA polymerase II are the most studied but factories can exist for RNA polymerase I and III; the nucleolus being seen as the prototype for transcription factories. It is possible to view them under both light and electron microscopy. The discovery of transcription factories has challenged the original view of how RNA polymerase interacts with the DNA polymer and it is thought that the presence of factories has important effects on gene regulation and nuclear structure. | 1 | Biochemistry |
In Prinzbach's optimized route from pagodane to dodecahedrane, the original low-yielding isomerization of parent pagodane to dodecahedrane is replaced by a longer but higher yielding sequence - which nevertheless still relies heavily on pagodane derivatives. In the scheme below, the divergence from the original happens after compound 16. | 0 | Organic Chemistry |
A newer chiral derivatizing agent (CDA), α-cyano-α-fluoro (2-naphthyl)-acetic acid (2-CFNA) was prepared in optically pure form by the chiral HPLC separation of a racemic 2-CFNA methyl ester. This ester was obtained by fluorination of methyl α-cyano (2-naphthyl) acetate with FClO3. 2-CFNA has been shown to be a superior CDA than Mosher's agent to determine the enantiomeric excess of a primary alcohol. | 4 | Stereochemistry |
When the electric field of a propagating beam of light oscillates in a direction perpendicular to its direction of propagation, it is said to be a polarized transverse wave. Light with an electric field constrained to a particular angle in the transverse plane is said to be linearly polarized. When linearly polarized light is transmitted through an isotropic material — a material that exhibits the same physical properties in all spatial directions — the amount of light absorbed by the material is the same when measured for all angles of the polarized light. The resulting absorbance spectrum is featureless as a function of the polarization angle.
A material said to be anisotropic exhibits different physical properties, like absorbance, refractive index, conductivity and so on, along different spatial directions. Thus, when a linearly polarized beam of light is passed through an anisotropic material and measured for different angles of polarization, the absorption of the light is different for different polarization angles. The resulting absorbance spectrum exhibits varying degrees of absorbance that correspond to the materials degree of anisotropy.
When a polarized THz beam of light is transmitted through an anisotropic material, the resulting absorbance spectrum exhibits varying degrees of absorbance that correspond to the anisotropy of the material. If measurements are made at different frequencies across the THz spectrum (between about 0.3 to 3 THz) at a particular THz polarization angle, the resulting absorbance spectrum may also vary with frequency. This occurs because the vibrational modes of the molecules in the material absorb light at different frequencies. In protein molecules, for example, many of these vibrational modes oscillate within the range of terahertz frequencies. When the molecules in a material are arranged in the same orientation, the internal vibrational properties of the molecules may be identified using anisotropic terahertz microspectroscopy (ATM). This molecular alignment is found in single crystals of sucrose, fructose, oxalic acid, and other molecular crystals like protein crystals. | 7 | Physical Chemistry |
In a 1925 paper, F.H. Constable described the linear relationship observed for the reaction parameters of the catalytic dehydrogenation of primary alcohols with copper-chromium oxide. | 7 | Physical Chemistry |
Glare caused from surfaces with high solar reflectance may present visibility concerns that can limit PDRC application, particularly within urban environments at the ground level. PDRCs that use a "scattering system" to generate reflection in a more diffused manner have been developed and are "more favorable in real applications," as per Lin et al.
Low-cost PDRC colored paint coatings, which reduce glare and increase the color diversity of PDRC surfaces, have also been developed. While some of the surface's solar reflectance is lost in the visible light spectrum, colored PDRCs can still exhibit significant cooling power, such as a coating by Zhai et al., which used a α- coating (resembling the color of the compound) to develop a non-toxic paint that demonstrated a solar reflectance of 99% and heat emissivity of 97%.
Generally it is noted that there is a tradeoff between cooling potential and darker colored surfaces. Less reflective colored PDRCs can also be applied to walls while more reflective white PDRCs can be applied to roofs to increase visual diversity of vertical surfaces, yet still contribute to cooling. | 7 | Physical Chemistry |
A sequence in biology is the one-dimensional ordering of monomers, covalently linked within a biopolymer; it is also referred to as the primary structure of a biological macromolecule. While it can refer to many different molecules, the term sequence is most often used to refer to a DNA sequence. | 1 | Biochemistry |
GenePattern is a powerful scientific workflow system that provides access to hundreds of genomic analysis tools. Use these analysis tools as building blocks to design sophisticated analysis pipelines that capture the methods, parameters, and data used to produce analysis results. Pipelines can be used to create, edit and share reproducible in silico results. | 1 | Biochemistry |
Galvanic shock or oral galvanism is a term used for the association of oral symptoms due to electric currents occurring between different types of metal used in amalgam dental fillings and their interactions with the electrolytes in saliva. Other than individual sensitivity to amalgam, which can produce oral lesions, no associated adverse effects to amalgam have been found. However, Mutter in a German study concluded that "removal of dental amalgam leads to permanent improvement of various chronic complaints in a relevant number of patients in various trials".
The condition of galvanic shock was originally proposed in 1878, and became well known in Sweden during the 1970s and 80s, because of a campaign to raise awareness, and replace dental amalgam fillings containing mercury with other compounds such as ceramic or polymer restorations. | 8 | Metallurgy |
Phenol is readily alkylated at the ortho positions using alkenes in the presence of a Lewis acid such as aluminium phenoxide:
: CH=CR + CHOH → RCHCH-2-CHOH
More than 100,000 tons of tert-butyl phenols are produced annually (year: 2000) in this way, using isobutylene (CH=CMe) as the alkylating agent. Especially important is 2,6-ditert-butylphenol, a versatile antioxidant. | 0 | Organic Chemistry |
It is possible to use DNA profiling as evidence of genetic relationship although such evidence varies in strength from weak to positive. Testing that shows no relationship is absolutely certain. Further, while almost all individuals have a single and distinct set of genes, ultra-rare individuals, known as "chimeras", have at least two different sets of genes. There have been two cases of DNA profiling that falsely suggested that a mother was unrelated to her children. | 1 | Biochemistry |
In the setting of standards, agencies make political and technical/scientific decisions based on how the water will be used. In the case of natural water bodies, agencies also make some reasonable estimate of pristine conditions. Natural water bodies will vary in response to a region's environmental conditions, whereby water composition is influenced by the surrounding geological features, sediments, and rock types, topography, hydrology, and climate. Environmental scientists and aqueous geochemists work to interpret the parameters and environmental conditions that impact the water quality of a region, which in turn helps to identify the sources and fates of contaminants. Environmental lawyers and policymakers work to define legislation with the intention that water is maintained at an appropriate quality for its identified use.
Another general perception of water quality is that of a simple property that tells whether water is polluted or not. In fact, water quality is a complex subject, in part because water is a complex medium intrinsically tied to the ecology, geology, and anthropogenic activities of a region. Industrial and commercial activities (e.g. manufacturing, mining, construction, transport) are a major cause of water pollution as are runoff from agricultural areas, urban runoff and discharge of treated and untreated sewage. | 3 | Analytical Chemistry |
The molecular configuration of a molecule is the permanent geometry that results from the spatial arrangement of its bonds. The ability of the same set of atoms to form two or more molecules with different configurations is stereoisomerism. This is distinct from constitutional isomerism which arises from atoms being connected in a different order. Conformers which arise from single bond rotations, if not isolatable as atropisomers, do not count as distinct molecular configurations as the spatial connectivity of bonds is identical. | 4 | Stereochemistry |
* Agricola, Georg. De re metallica. 1st ed. Basil: Hieronymus Froben & Nicolaus Episcopius, 1556.
* Agricola, Georg. De re metallica. 2nd ed. Basil: Hieronymus Froben & Nicolaus Episcopius, 1561.
* Agricola, Georg. De re metallica. Basil: Ludwig König, 1621.
* Agricola, Georg. De Re Metallica. Basil: Emanuel König, 1657.
* Agricola, Georg. Vom Bergkwerck. Translated by Philipp Bech. Basel: Hieronymus Froben & Nicolaus Episcopius, 1557.
* Agricola, Georg. Bergwerck Buch. Translated by Philipp Bech. Basil: Ludwig König, 1621.
* Agricola, Georg. Zwölf Bücher vom Berg- und Hüttenwesen. Edited by Carl Schiffner and others. Translated by Carl Schiffner. Berlin: VDI-Verlag, 1928.
* Agricola, Georg. Opera di Giorgio Agricola de L’Arte de Metalli. Basil: Hieronymus Froben & Nicolaus Episcopius, 1563.
* Agricola, Georg. De Re Metallica. Translated by Herbert Clark Hoover and Lou Henry Hoover. 1st English ed. London: The Mining Magazine, 1912.
* Agricola, Georg. De Re Metallica. Translated by Herbert Clark Hoover and Lou Henry Hoover. New York: Dover Publications, 1950. Reprint of the 1912 edition.
* Agricola, Georg. De Re Metallica. Translated by Herbert Clark Hoover and Lou Henry Hoover. New York: Dover Publications, 1986. Reprint of the 1950 reprint of the 1912 edition. | 8 | Metallurgy |
* Methyl esters are often susceptible to decarboxylation in the Krapcho decarboxylation.
* Phenyl esters react to hydroxyarylketones in the Fries rearrangement.
* Specific esters are functionalized with an α-hydroxyl group in the Chan rearrangement.
* Esters with β-hydrogen atoms can be converted to alkenes in ester pyrolysis.
*A direct conversion of esters to nitriles.
* Pairs of esters are coupled to give α-hydroxyketones in the acyloin condensation | 0 | Organic Chemistry |
Nitrification is the biological oxidation of ammonia to nitrate via the intermediary nitrite. Nitrification is an important step in the nitrogen cycle in soil. The process of complete nitrification may occur through separate organisms or entirely within one organism, as in comammox bacteria. The transformation of ammonia to nitrite is usually the rate limiting step of nitrification. Nitrification is an aerobic process performed by small groups of autotrophic bacteria and archaea. | 1 | Biochemistry |
Androsterone glucuronide (ADT-G) is a major circulating and urinary metabolite of testosterone and dihydrotestosterone (DHT). It accounts for 93% of total androgen glucuronides in women. ADT-G is formed from androsterone by UDP-glucuronosyltransferases, with the major enzymes being UGT2B15 and UGT2B17. It is a marker of acne in women while androstanediol glucuronide is a marker of hirsutism (excess hair growth) in women. | 1 | Biochemistry |
Rotational spectroscopy has primarily been used to investigate fundamental aspects of molecular physics. It is a uniquely precise tool for the determination of molecular structure in gas-phase molecules. It can be used to establish barriers to internal rotation such as that associated with the rotation of the group relative to the group in chlorotoluene (). When fine or hyperfine structure can be observed, the technique also provides information on the electronic structures of molecules. Much of current understanding of the nature of weak molecular interactions such as van der Waals, hydrogen and halogen bonds has been established through rotational spectroscopy. In connection with radio astronomy, the technique has a key role in exploration of the chemical composition of the interstellar medium. Microwave transitions are measured in the laboratory and matched
to emissions from the interstellar medium using a radio telescope. was the first stable polyatomic molecule to be identified in the interstellar medium. The measurement of chlorine monoxide is important for atmospheric chemistry. Current projects in astrochemistry involve both laboratory microwave spectroscopy and observations made using modern radiotelescopes such as the Atacama Large Millimeter/submillimeter Array (ALMA). | 7 | Physical Chemistry |
The similarities of yttrium to the lanthanides are so strong that the element has been grouped with them as a rare-earth element, and is always found in nature together with them in rare-earth minerals. Chemically, yttrium resembles those elements more closely than its neighbor in the periodic table, scandium, and if physical properties were plotted against atomic number, it would have an apparent number of 64.5 to 67.5, placing it between the lanthanides gadolinium and erbium.
It often also falls in the same range for reaction order, resembling terbium and dysprosium in its chemical reactivity. Yttrium is so close in size to the so-called yttrium group of heavy lanthanide ions that in solution, it behaves as if it were one of them. Even though the lanthanides are one row farther down the periodic table than yttrium, the similarity in atomic radius may be attributed to the lanthanide contraction.
One of the few notable differences between the chemistry of yttrium and that of the lanthanides is that yttrium is almost exclusively trivalent, whereas about half the lanthanides can have valences other than three; nevertheless, only for four of the fifteen lanthanides are these other valences important in aqueous solution (Ce, Sm, Eu, and Yb). | 8 | Metallurgy |
Noncompetitive inhibitors of CYP2C9 enzyme include nifedipine, tranylcypromine, phenethyl isothiocyanate, and 6-hydroxyflavone. Computer docking simulation and constructed mutants substituted indicate that the noncompetitive binding site of 6-hydroxyflavone is the reported allosteric binding site of CYP2C9 enzyme. | 1 | Biochemistry |
LongSAGE was a more robust version of the original SAGE developed in 2002 which had a higher throughput, using 20 μg of mRNA to generate a cDNA library of thousands of tags. Robust LongSage (RL-SAGE) Further improved on the LongSAGE protocol with the ability to generate a library with an insert size of 50 ng mRNA, much smaller than previous LongSAGE insert size of 2 μg mRNA and using a lower number of ditag polymerase chain reactions (PCR) to obtain a complete cDNA library. | 1 | Biochemistry |
Evaluating () in and using the relation between the isothermal compressibility and the structure factor at the origin yields the compressibility equation: | 7 | Physical Chemistry |
For coupling to mass spectrometry, the ions from the plasma are extracted through a series of cones into a mass spectrometer, usually a quadrupole. The ions are separated on the basis of their mass-to-charge ratio and a detector receives an ion signal proportional to the concentration.
The concentration of a sample can be determined through calibration with certified reference material such as single or multi-element reference standards. ICP-MS also lends itself to quantitative determinations through isotope dilution, a single point method based on an isotopically enriched standard. In order to increase reproducibility and compensate errors but sensitivity variation, an internal standard can be added.
Other mass analyzers coupled to ICP systems include double focusing magnetic-electrostatic sector systems with both single and multiple collector, as well as time of flight systems (both axial and orthogonal accelerators have been used). | 3 | Analytical Chemistry |
In 1845, Joule studied the free expansion of a gas into a larger volume. This became known as Joule expansion. The cooling of a gas by allowing it to expand freely is occasionally referred to as the Joule effect. | 7 | Physical Chemistry |
Salbutamol is the international nonproprietary name (INN) while albuterol is the United States Adopted Name (USAN). The drug is usually manufactured and distributed as the sulfate salt (salbutamol sulfate).
It was first sold by Allen & Hanburys (UK) under the brand name Ventolin, and has been used for the treatment of asthma ever since. The drug is marketed under many names worldwide. | 4 | Stereochemistry |
Noboru Tokita (February 20, 1923 - October 31, 2014) was a Uniroyal and later Cabot scientist known for his work on the processing of elastomers. | 7 | Physical Chemistry |
Protein interactions: To screen for protein–protein interactions and protein interactions with other molecules such as metabolites, lipids, DNA and small molecules.; enzyme inhibition assay: for high throughput drug candidate screening and to discover novel enzymes for use in biotechnology; screening antibody specificity. | 1 | Biochemistry |
For T, which is an anti-unitary Z symmetry generator
: T = UKUK = UU = U (U) = Φ,
where Φ is a diagonal matrix of phases. As a result, and , showing that
:U = Φ U Φ.
This means that the entries in Φ are ±1, as a result of which one may have either . This is specific to the anti-unitarity of T. For a unitary operator, such as the parity, any phase is allowed.
Next, take a Hamiltonian invariant under T. Let |a⟩ and T|a⟩ be two quantum states of the same energy. Now, if , then one finds that the states are orthogonal: a result called Kramers' theorem. This implies that if , then there is a twofold degeneracy in the state. This result in non-relativistic quantum mechanics presages the spin statistics theorem of quantum field theory.
Quantum states that give unitary representations of time reversal, i.e., have , are characterized by a multiplicative quantum number, sometimes called the T-parity. | 7 | Physical Chemistry |
An apoenzyme (or, generally, an apoprotein) is the protein without any small-molecule cofactors, substrates, or inhibitors bound. It is often important as an inactive storage, transport, or secretory form of a protein. This is required, for instance, to protect the secretory cell from the activity of that protein.
Apoenzymes become active enzymes on addition of a cofactor. Cofactors can be either inorganic (e.g., metal ions and iron-sulfur clusters) or organic compounds, (e.g., [Flavin group|flavin] and heme). Organic cofactors can be either prosthetic groups, which are tightly bound to an enzyme, or coenzymes, which are released from the enzyme's active site during the reaction. | 0 | Organic Chemistry |
Groundwater and drinking water contamination from industrial discharge including trichloroethylene is a major concern for human health and has precipitated numerous incidents and lawsuits in the United States.
The 1995 non-fiction book A Civil Action was written about a lawsuit (Anderson v. Cryovac) against following the increase in cancer cases after trichloroethylene pollution incidents and it was adapted to cinema in 1998.
TCE has been used as a recreational drug. Common methods of taking trichloroethylene recreationally include inhalation from a rag (similar to taking an inhalational anaesthetic) and drinking. Most TCE abusers were young people and workers who use the chemical in their workplace. The main reason for abuse is TCE's euphoriant and slight hallucinogenic effect. Some workers had become addicted to TCE. | 2 | Environmental Chemistry |
This is a generalization of Eq. (1) to a biphasic system with ellipsoidal inclusions of conductivity into a matrix of conductivity . The fraction of inclusions is and the system is dimensional. For randomly oriented inclusions,
where the s denote the appropriate doublet/triplet of depolarization factors which is governed by the ratios between the axis of the ellipse/ellipsoid. For example: in the case of a circle (, ) and in the case of a sphere (, , ). (The sum over the s is unity.)
The most general case to which the Bruggeman approach has been applied involves bianisotropic ellipsoidal inclusions. | 7 | Physical Chemistry |
Two hydrated bilayers experience strong repulsion as they approach each other. These forces have been measured using the Surface forces apparatus (S.F.A), an instrument used for measuring forces between surfaces. This repulsion was first proposed by Langmuir and was thought to arise due to water molecules that hydrate the bilayers. Hydration repulsion can thus be defined as the work required in removing the water molecules around hydrophilic molecules (like lipid head groups) in the bilayer system. As water molecules have an affinity towards hydrophilic head groups, they try to arrange themselves around the head groups of the lipid molecules and it becomes very hard to separate this favorable combination.
Experiments performed through SFA have confirmed that the nature of this force is an exponential decline. The potential V is given by
where C (>0) is a measure of the hydration interaction energy for hydrophilic molecules of the given system, λ is a characteristic length scale of hydration repulsion and z is the distance of separation. In other words, it is on distances up to this length that molecules/surfaces fully experience this repulsion. | 6 | Supramolecular Chemistry |
Electro-osmotic flow is commonly used in microfluidic devices, soil analysis and processing, and chemical analysis, all of which routinely involve systems with highly charged surfaces, often of oxides. One example is capillary electrophoresis, in which electric fields are used to separate chemicals according to their electrophoretic mobility by applying an electric field to a narrow capillary, usually made of silica. In electrophoretic separations, the electroosmotic flow affects the elution time of the analytes.
Electro-osmotic flow is actuated in a FlowFET to electronically control fluid flow through a junction.
It is projected that micro fluidic devices utilizing electroosmotic flow will have applications in medical research. Once controlling this flow is better understood and implemented, the ability to separate fluids on the atomic level will be a vital component for drug dischargers. Mixing fluids at the micro scale is currently troublesome. It is believed that electrically controlling fluids will be the method in which small fluids are mixed.
A controversial use of electro-osmotic systems is the control rising damp in the walls of buildings. While there is little evidence to suggest that these systems can be useful in moving salts in walls, such systems are claimed to be especially effective in structures with very thick walls.
However some claim that there is no scientific base for those systems, and cite several examples for their failure.
Electro-osmosis can also be used for self-pumping pores powered by chemical reactions rather than electric fields. This approach, using , has been demonstrated and modeled with the Nernst-Planck-Stokes equations. | 7 | Physical Chemistry |
In this example, a gene from mammalian gene library will be subcloned into a bacterial plasmid (destination platform). The bacterial plasmid is a piece of circular DNA which contains regulatory elements allowing for the bacteria to produce a gene product (gene expression) if it is placed in the correct place in the plasmid. The production site is flanked by two restriction enzyme cutting sites "A" and "B" with incompatible sticky ends.
The mammalian DNA does not come with these restriction sites, so they are built in by overlap extension PCR. The primers are designed to put the restriction sites carefully, so that the coding of the protein is in-frame, and a minimum of extra amino acids is implanted on either side of the protein.
Both the PCR product containing the mammalian gene with the new restriction sites and the destination plasmid are subjected to restriction digestion, and the digest products are purified by gel electrophoresis.
The digest products, now containing compatible sticky ends with each other (but incompatible sticky ends with themselves) are subjected to ligation, creating a new plasmid which contains the background elements of the original plasmid with a different insert.
The plasmid is transformed into bacteria and the identity of the insert is confirmed by DNA sequencing. | 1 | Biochemistry |
Submarine groundwater discharge (SGD) is a hydrological process which commonly occurs in coastal areas. It is described as submarine inflow of fresh-, and brackish groundwater from land into the sea. Submarine Groundwater Discharge is controlled by several forcing mechanisms, which cause a hydraulic gradient between land and sea. Considering the different regional settings the discharge occurs either as (1) a focused flow along fractures in karst and rocky areas, (2) a dispersed flow in soft sediments, or (3) a recirculation of seawater within marine sediments. Submarine Groundwater Discharge plays an important role in coastal biogeochemical processes and hydrological cycles such as the formation of offshore plankton blooms, hydrological cycles, and the release of nutrients, trace elements and gases. It affects coastal ecosystems and has been used as a freshwater resource by some local communities for millennia. | 9 | Geochemistry |
A goniometer is used to document initial and subsequent range of motion, at the visits for occupational injuries, and by disability evaluators to determine a permanent disability. This is to evaluate progress, and also for medico-legal purposes. It is a tool to evaluate Waddell's signs (findings that may indicate symptom magnification.) | 7 | Physical Chemistry |
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