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Site-specific pollution induced degradation is measured through the combination of the three portions of the sediment quality triad. The sediment chemistry, sediment toxicity, and the field effects to benthic organisms are compared quantitatively. Data is most useful when it has been normalized to reference site values by converting them to reference-to-ratio values (Chapman et al. 1986; Chapman 1989). The reference site is chosen to be the site with the least contamination with respect to the other sites sampled. Once normalized, data between portions of the triad are able to be compared even when large differences in measurements or units exits (Chapman, 1990). From the combination of the results from each portion of the triad a multivariate figure is developed and used to determine the level of degradation. | 2 | Environmental Chemistry |
The thermocouple's behaviour is captured by a characteristic function , which needs only to be consulted at two arguments:
In terms of the Seebeck coefficients, the characteristic function is defined by
The constant of integration in this indefinite integral has no significance, but is conventionally chosen such that .
Thermocouple manufacturers and metrology standards organizations such as NIST provide tables of the function that have been measured and interpolated over a range of temperatures, for particular thermocouple types (see External links section for access to these tables). | 8 | Metallurgy |
The conductivity of a solution is highly temperature dependent, so it is important either to use a temperature compensated instrument, or to calibrate the instrument at the same temperature as the solution being measured. Unlike metals, the conductivity of common electrolytes typically increases with increasing temperature.
Over a limited temperature range, the way temperature affects the conductivity of a solution can be modeled linearly using the following formula:
where
:T is the temperature of the sample,
:T is the calibration temperature,
:σ is the electrical conductivity at the temperature T,
:σ,
:α is the temperature compensation gradient of the solution.
The temperature compensation gradient for most naturally occurring samples of water is about 2%/°C; however it can range between 1 and 3%/°C. The compensation gradients for some common water solutions are listed in the table below. | 7 | Physical Chemistry |
Martensite is a very hard form of steel crystalline structure. It is named after German metallurgist Adolf Martens. By analogy the term can also refer to any crystal structure that is formed by diffusionless transformation. | 8 | Metallurgy |
MLPA facilitates the amplification and detection of multiple targets with a single primer pair. In a standard multiplex PCR reaction, each fragment needs a unique amplifying primer pair. These primers being present in a large quantity result in various problems such as dimerization and false priming. With MLPA, amplification of probes can be achieved. Thus, many sequences (up to 40) can be amplified and quantified using just a single primer pair. MLPA reaction is fast, inexpensive and very simple to perform.
MLPA has a variety of applications including detection of mutations and single nucleotide polymorphisms, analysis of DNA methylation, relative mRNA quantification, chromosomal characterisation of cell lines and tissue samples, detection of gene copy number, detection of duplications and deletions in human cancer predisposition genes such as BRCA1, BRCA2, hMLH1 and hMSH2 and aneuploidy determination. MLPA has potential application in prenatal diagnosis both invasive and noninvasive.
Recent studies have shown that MLPA (as well as another variants such as iMLPA) is a robust technique for inversion characterisation. | 1 | Biochemistry |
Most enzymes cannot tolerate extremely high salt concentrations. The ions interfere with the weak ionic bonds of proteins. Typical enzymes are active in salt concentrations of 1-500 mM. As usual there are exceptions such as the halophilic algae and bacteria. | 1 | Biochemistry |
Tungsten plays a large and indispensable role in modern high-tech industry. Up to 500,000 tons of raw tungsten ore are mined each year by Wolfram Bergbau und Hütten AG (WHB)in Felbertal, Austria, which is the largest scheelite deposit in Europe. 25% of the run-of-mine ore are separated as waste before entering the mill. | 3 | Analytical Chemistry |
In view of its performance, the process seemed a suitable basis for the development of more efficient variants. Around 1940, the Japanese built several small reduction furnaces operating at lower temperatures: one at Tsukiji (1.8 m × 60 m), two at Hachinohe (2 furnaces of 2.8 m × 50 m), and three at Takasago (2 furnaces of 1.83 m × 27 m and 1 furnace of 1.25 m × 17 m). However, since they do not produce Luppen, they cannot be equated with the Krupp-Renn process.
Although direct reduction in a rotary furnace has been the subject of numerous developments, the logical descendant of the Krupp-Renn process is the "Krupp-CODIR process". Developed in the 1970s, it is based on the general principles of the Krupp-Renn process with a lower temperature reduction, typically between 950 and 1,050 °C, which saves fuel but is insufficient to achieve partial melting of the charge. The addition of basic corrective additives (generally limestone or dolomite) mixed with the ore allows the removal of sulfur from the coal, although the thermolysis of these additives is highly endothermic. This process has been adopted by three plants: Dunswart Iron & Steel Works in South Africa in 1973, Sunflag Iron and Steel in 1989, and Goldstar Steel & Alloy in India in 1993. Although the industrial application is now well established, the process has not had the impact of its predecessor.
Finally, there are many post-Krupp-Renn direct reduction processes based on a tubular rotary furnace. At the beginning of the 21st century, their combined output represented between 1% and 2% of world steel production. In 1935 and 1960, the output of the Krupp-Renn process (1 and 2 million tons respectively) represented just under 1% of world steel production. | 8 | Metallurgy |
Diseases which can be transmitted from one organism to another are known as infectious diseases, and the causative biological agent involved is known as a pathogen. The process by which the pathogen is introduced into the body is known as inoculation, and the organism it affects is known as a biological host. When the pathogen establishes itself in a step known as colonization, it can result in an infection, consequently harming the host directly or through the harmful substances called toxins it can produce. This results in the various symptoms and signs characteristic of an infectious disease like pneumonia or diphtheria.
Countering the various infectious diseases is very important for the survival of the susceptible organism, in particular, and the species, in general. This is achieved by the host by eliminating the pathogen and its toxins or rendering them nonfunctional. The collection of various cells, tissues and organs that specializes in protecting the body against infections is known as the immune system. The immune system accomplishes this through direct contact of certain white blood cells with the invading pathogen involving an arm of the immune system known as the cell-mediated immunity, or by producing substances that move to sites distant from where they are produced, "seek" the disease-causing cells and toxins by specifically binding with them, and neutralize them in the process–known as the humoral arm of the immune system. Such substances are known as soluble antibodies and perform important functions in countering infections. | 1 | Biochemistry |
Snail shell is an aragonite-protein composite, with a hierarchical groove structure. The regular roughness of the structure creates a hydrophilic structure, a thin layer of water trapped on the surface, that doesn’t allow oil to attach to the snail shell, thereby keeping the shell clean. These surface properties of snail shell have inspired the use of similar surface patterns on ceramic tiles and ceramic structures by the INAX corporation, which applies these techniques to kitchens and bathrooms. | 7 | Physical Chemistry |
Huntingtons disease (HD) is an inherited neurodegenerative disorder, with symptoms emerging during an individuals mid-adulthood. The most noticeable symptoms of this progressive disease are cognitive and motor impairments, as well as behavioral alterations. These impairments can develop into dementia, chorea, and eventually death. At the molecular level, HD results from a mutation in the huntingtin protein (Htt). More specifically, there is an abnormal repetition of a CAG sequence towards the 5’-end of the gene, which then leads to the development of a toxic polyglutamine (polyQ) stretch in the protein. The mutated Htt protein affects an individual's proper neural functions by inhibiting the action of REST/NRSF.
REST/NRSF is an important silencer element that binds to regulatory regions to control the expression of certain proteins involved in neural functions. The mechanistic actions of huntingtin are still not fully understood, but a correlation between Htt and REST/NRSF exists in HD development. By attaching to the REST/NRSF, the mutated huntingtin protein inhibits the action of the silencer element, and retains it in the cytosol. Thus, REST/NRSF cannot enter the nucleus and bind to the 21 base-pair RE-1/NRSE regulatory element. An adequate repression of specific target genes are of fundamental importance, as many are involved in the proper development of neuronal receptors, neurotransmitters, synaptic vesicle proteins, and channel proteins. A deficiency in the proper development of these proteins can cause the neural dysfunctions seen in Huntingtons disease. In addition to the lack of repression due to the inactive REST/NRSF, mutated huntingtin protein can also decrease the transcription of the brain-derived neurotropic factor (BDNF) gene. BDNF influences the survival and development of neurons in the central nervous system as well as the peripheral nervous system. This abnormal repression occurs when the RE1/NRSE region within the BDNF promoter region is activated by the binding of REST/NRSF, which leads to the lack of transcription of the BDNF gene. Hence, the anomalous repression of the BDNF protein suggests a significant impact in Huntingtons disease. | 1 | Biochemistry |
Kazzinc selected the copper ISASMELT process for its Ust-Kamenogorsk metallurgical complex. It is designed to treat 290,000 t/y of copper concentrate and was commissioned in 2011. A projected capital cost for the smelter and refinery in 2006 was US$178 million. | 8 | Metallurgy |
Level M vectors are similar to level 2 vectors, but have a BsaI site located upstream of the two inverted BpiI sites. When one or several genes are cloned in a level M vector, a second BsaI is added at the end of the construct via a Level M end-linker (ref). This allows a fragment containing all assembled genes to be excised from the vector and subcloned in a next level of cloning (Level P). | 1 | Biochemistry |
HITRAN (an acronym for High Resolution Transmission) molecular spectroscopic database is a compilation of spectroscopic parameters used to simulate and analyze the transmission and emission of light in gaseous media, with an emphasis on planetary atmospheres. The knowledge of spectroscopic parameters for transitions between energy levels in molecules (and atoms) is essential for interpreting and modeling the interaction of radiation (light) within different media.
For half a century, HITRAN has been considered to be an international standard which provides the user a recommended value of parameters for millions of transitions for different molecules. HITRAN includes both experimental and theoretical data which are gathered from a worldwide network of contributors as well as from articles, books, proceedings, databases, theses, reports, presentations, unpublished data, papers in-preparation and private communications. A major effort is then dedicated to evaluating and processing the spectroscopic data. A single transition in HITRAN has many parameters, including a default 160-byte fixed-width format used since HITRAN2004. Wherever possible, the retrieved data are validated against accurate laboratory data.
The original version of HITRAN was compiled by the US Air Force Cambridge Research Laboratories (1960s) in order to enable surveillance of military aircraft detected through the terrestrial atmosphere. One of the early applications of HITRAN was a program called Atmospheric Radiation Measurement (ARM) for the US Department of Energy. In this program spectral atmospheric measurements were made around the globe in order to better understand the balance between the radiant energy that reaches Earth from the sun and the energy that flows from Earth back out to space. The US Department of Transportation also utilized HITRAN in its early days for monitoring the gas emissions (NO, SO, NO) of super-sonic transports flying at high altitude. HITRAN was first made publicly available in 1973 and today there are a multitude of ongoing and future NASA satellite missions which incorporate HITRAN. One of the NASA missions currently utilizing HITRAN is the Orbiting Carbon Observatory (OCO) which measures the sources and sinks of CO in the global atmosphere. HITRAN is a free resource and is currently maintained and developed at the Center for Astrophysics Harvard & Smithsonian, Cambridge MA, USA ([https://www.cfa.harvard.edu/research/hitran-and-hitemp-database CFA/HITRAN]).
HITRAN is the worldwide standard for calculating or simulating atmospheric molecular transmission and radiance from the microwave through ultraviolet region of the spectrum. The HITRAN database is officially released on a quadrennial basis, with updates posted in the intervening years on [https://hitran.org HITRANonline]. There is a new journal article published in conjunction with the most recent release of the HITRAN database, and users are strongly encouraged to use the most recent edition. Throughout HITRANs history, there have been around 50,000 unique users of the database and in recent years there are over 24,000 users registered on [https://hitran.org HITRANonline]. There are YouTube tutorials on the [https://hitran.org HITRANonline'] webpage to answer frequently asked questions by users. | 7 | Physical Chemistry |
Aminoallyl NTPs are used for indirect DNA labeling in PCR, nick translation, primer extensions and cDNA synthesis. These labeled NTPs are helpful because of their application in molecular biology labs where they do not have the capacity to handle radioactive material. For example, 5-(3-Aminoallyl)-Uridine(AA-UTPs) are more effective for high density labeling of DNA than pre-labeling the DNA. After the enzymatic addition of the NTPs, amine reactant fluorescent dyes can be added for detection of the DNA molecule. When incorporated into DNA or RNA molecules by DNA/RNA polymerase, 5-(3-aminoallyl)-UTP provide a reactive group for the addition of other chemical groups. Thus aminoallyl modified DNA or RNA can be labeled with any compound which has an amine-reactive group.
aa-NTPs incorporated into DNA/RNA in combination with a secondary dye coupling reagents can probe for an array analysis.
cDNA relies on aminoallyl labeling for detection purposes. Although direct labeling of dNTP is the quickest and cheapest method of fluorescent labeling, it is disadvantageous as the sequence allows for only one modified nucleotide for use. Another disadvantage of direct labeling is the bulky nucleotides, however this can be overcome by indirect labeling using aminoallyl modified nucleotides. An easy way to check for labeling success is the color;Good labeling will result in visible blue (Cy5) or red (Cy3) color in the final material.
Another process which uses aminoallyl labeling is NASBA ( Nucleic Acid Sequence Based Amplification), a highly sensitive technique for amplifying RNA. In this specific case, the aaUTP modified RNAs were tagged with fluorescent market Cy3. NASBA combined with aminoallyl-UTP labeling is very useful for many different areas of microbial diagnostics including environmental monitoring, bio threat detection, industrial process monitoring and clinical microbiology. DNA microarray is another method which utilizes specifically AA-NTP's making DNA microarray testing quicker and cheaply.
Post-synthesis labeling avoids the problems found in direct enzymatic incorporation of Cy-labeled dNTPs by generating probes with equal labeling effectiveness. With indirect labeling, amine-modified NTPs are incorporated during reverse transcription, RNA amplification, or PCR. Amino allyl-NTPs are incorporated with similar efficiency as unmodified NTPs during polymerization.
Concerns with labeling:
The amine group, in aminoallyl-modified nucleotide, is reactive with dyes such as the cyanine series, or other patented dyes. A problem arises when the dyes react with buffering agents which are necessary for the proper storage of the nucleotides. However, a carbonate buffer can be used to overcome this problem. | 1 | Biochemistry |
Some elements can form several kinds of anions, and compounds may exist with more than one. Examples include the iodate periodates, sulfite sulfates, selenate selenites, tellurite tellurates, nitrate nitrites, phosphate phosphites, and arsenate arsenites.
These kinds also include different oligomeric forms such as phosphates or fluorotitanates, such as [TiF] and [TiF]. | 7 | Physical Chemistry |
The typical framework building blocks are polyhedral units, with 6-coordinate metal centres. Usually, these units share edges and/or vertices. The coordination number of the oxide ligands varies according to their location in the cage. Surface oxides tend to be terminal or doubly bridging oxo ligands. Interior oxides are typically triply bridging or even octahedral. POMs are sometimes viewed as soluble fragments of metal oxides.
Recurring structural motifs allow POMs to be classified. Iso-polyoxometalates (isopolyanions) feature octahedral metal centers. The heteropolymetalates form distinct structures because the main group center is usually tetrahedral. The Lindqvist and Keggin structures are common motifs for iso- and heteropolyanions, respectively.
Polyoxometalates typically exhibit coordinate metal-oxo bonds of different multiplicity and strength. In a typical POM such as the Keggin structure , each addenda center connects to single terminal oxo ligand, four bridging µ-O ligands and one bridging µ-O deriving from the central heterogroup. Metal–metal bonds in polyoxometalates are normally absent and owing to this property, F. Albert Cotton opposed to consider polyoxometalates as form of cluster materials. However, metal-metal bonds are not completely absent in polyoxometalates and they are often present among the highly reduced species. | 7 | Physical Chemistry |
Most other cells cannot divide indefinitely as after a few cycles of cell division the cells stop expressing an enzyme telomerase. The genetic material, in the form of deoxyribonucleic acid (DNA), continues to shorten with each cell division, and cells eventually stop dividing when they sense that their DNA is critically shortened. However, this enzyme in "youthful" cells replaces these lost bits (nucleotides) of DNA, thus making almost unlimited cycles of cell division possible. It is believed that the above-mentioned tissues have a constitutional elevated expression of telomerase. When ultimately many cells are produced by a single cell, clonal expansion is said to have taken place. | 1 | Biochemistry |
Immunogold labeling can be used to visualize more than one target simultaneously. This can be achieved in electron microscopy by using two different-sized gold particles. An extension of this method used three different sized gold particles to track the localisation of regulatory peptides. A more complex method of multi-site labeling involves labeling opposite sides of an antigenic site separately, the immunogold particles attached to both sides can then be viewed simultaneously. | 1 | Biochemistry |
The understanding of CHF phenomenon and an accurate prediction of the CHF condition are important for safe and economic design of many heat transfer units including nuclear reactors, fossil fuel boilers, fusion reactors, electronic chips, etc. Therefore, the phenomenon has been investigated extensively over the world since Nukiyama first characterized it. In 1950 Kutateladze suggested the hydrodynamical theory of the burnout crisis. Much of significant work has been done during the last decades with the development of water-cooled nuclear reactors. Now many aspects of the phenomenon are well understood and several reliable prediction models are available for conditions of common interests.
The use of the term critical heat flux (CHF) is inconsistent among authors. The United States Nuclear Regulatory Commission has suggested using the term “critical boiling transition” (CBT) to indicate the phenomenon associated with a significant reduction in two-phase heat transfer. For a single species, the liquid phase generally has considerably better heat transfer properties than the vapor phase, namely thermal conductivity. So in general CBT is the result of some degree of liquid deficiency to a local position along a heated surface. The two mechanisms that result in reaching CBT are: departure from nucleate boiling (DNB) and liquid film dryout.
Departure from nucleate boiling (DNB) occurs in sub-cooled flows and bubbly flow regimes. DNB happens when many bubbles near the heated surface coalesce and impede the ability of local liquid to reach the surface. The mass of vapor between the heated surface and local liquid may be referred to as a vapor blanket.
Dryout means the disappearance of liquid on the heat transfer surface which results in the CBT. Dryout of liquid film occurs in annular flow. Annular flow is characterized by a vapor core, liquid film on the wall, and liquid droplets entrained within the core. Shear at the liquid-vapor interface drives the flow of the liquid film along the heated surface. In general, the two-phase HTC increases as the liquid-film thickness decreases. The process has been shown to occur over many instances of dryout events, which span a finite duration and are local to a position. The CBT occurs when the fraction of time a local position is subjected to dryout becomes significant. A single dryout event, or even several dryout events, may be followed by periods of sustained contact between the liquid film and the previously dry region [https://mediaspace.wisc.edu/media/Dryout-rewet/1_7sn93wd2] . Many dryout events (hundreds or thousands) occurring in sequence are the mechanism for significant reduction in heat transfer-associated dryout CBT.
Post-CHF is used to denote the general heat transfer deterioration in flow boiling process, and liquid could be in the form of dispersed spray of droplets, continuous liquid core, or transition between the former two cases. Post-dryout can be specifically used to denote the heat transfer deterioration in the condition when liquid is only in the form of dispersed droplets, and denote the other cases by the term Post-DNB. | 7 | Physical Chemistry |
Boiling tea leaves in water extracts the tannins, theobromine, and caffeine out of the leaves and into the water, as an example of a solid-liquid extraction.
Decaffeination of tea and coffee is also an example of an extraction, where the caffeine molecules are removed from the tea leaves or coffee beans, often utilising supercritical fluid extraction with CO or standard solid-liquid extraction techniques. | 3 | Analytical Chemistry |
Anaerobic corrosion (also known as hydrogen corrosion) is a form of metal corrosion occurring in anoxic water. Typically following aerobic corrosion, anaerobic corrosion involves a redox reaction that reduces hydrogen ions and oxidizes a solid metal. This process can occur in either abiotic conditions through a thermodynamically spontaneous reaction or biotic conditions through a process known as bacterial anaerobic corrosion. Along with other forms of corrosion, anaerobic corrosion is significant when considering the safe, permanent storage of chemical waste. | 8 | Metallurgy |
Generally, levosalbutamol is well tolerated. Common mild side-effects include an elevated heart rate, muscle cramps, and gastric upset (including heartburn and diarrhea).
Symptoms of overdose in particular include: collapse into a seizure; chest pain (possible precursor of a heart attack); fast, pounding heartbeat, which may cause raised blood pressure (hypertension); irregular heartbeat (cardiac arrhythmia), which may cause paradoxical lowered blood pressure (hypotension); nervousness and tremor; headache; dizziness and nausea/vomiting; weakness or exhaustion (medical fatigue); dry mouth; and insomnia.
Rarer side effects may indicate a dangerous allergic reaction. These include: paradoxical bronchospasm (shortness of breath and difficulty breathing); skin itching, rash, or hives (urticaria); swelling (angioedema) of any part of the face or throat (which can lead to voice hoarseness), or swelling of the extremities. | 4 | Stereochemistry |
If the rate constants for the following reaction are and ; , then the rate equation is:
:For reactant A:
:For reactant B:
:For product C:
With the individual concentrations scaled by the total population of reactants to become probabilities, linear systems of differential equations such as these can be formulated as a master equation. The differential equations can be solved analytically and the integrated rate equations are
The steady state approximation leads to very similar results in an easier way. | 7 | Physical Chemistry |
These are stoichiometric compounds of hydrogen. Ionic or saline hydrides are composed of hydride bound to an electropositive metal, generally an alkali metal or alkaline earth metal. The divalent lanthanides such as europium and ytterbium form compounds similar to those of heavier alkaline earth metals. In these materials the hydride is viewed as a pseudohalide. Saline hydrides are insoluble in conventional solvents, reflecting their non-molecular structures. Ionic hydrides are used as bases and, occasionally, as reducing reagents in organic synthesis.
Typical solvents for such reactions are ethers. Water and other protic solvents cannot serve as a medium for ionic hydrides because the hydride ion is a stronger base than hydroxide and most hydroxyl anions. Hydrogen gas is liberated in a typical acid-base reaction.
:ΔH = −83.6 kJ/mol, ΔG = −109.0 kJ/mol
Often alkali metal hydrides react with metal halides. Lithium aluminium hydride (often abbreviated as LAH) arises from reactions of lithium hydride with aluminium chloride. | 0 | Organic Chemistry |
The geologic component of the carbon cycle operates slowly in comparison to the other parts of the global carbon cycle. It is one of the most important determinants of the amount of carbon in the atmosphere, and thus of global temperatures.
As the biological pump plays an important role in the Earths carbon cycle, significant effort is spent quantifying its strength. However, because they occur as a result of poorly constrained ecological interactions usually at depth, the processes that form the biological pump are difficult to measure. A common method is to estimate primary production fuelled by nitrate and ammonium as these nutrients have different sources that are related to the remineralisation of sinking material. From these it is possible to derive the so-called f-ratio, a proxy for the local strength of the biological pump. Applying the results of local studies to the global scale is complicated by the role the oceans circulation plays in different ocean regions. | 9 | Geochemistry |
The Gibbs–Duhem equation is useful because it relates individual chemical potentials. For example, in a binary mixture, at constant temperature and pressure, the chemical potentials of the two participants A and B are related by
where is the number of moles of A and is the number of moles of B. Every instance of phase or chemical equilibrium is characterized by a constant. For instance, the melting of ice is characterized by a temperature, known as the melting point at which solid and liquid phases are in equilibrium with each other. Chemical potentials can be used to explain the slopes of lines on a phase diagram by using the Clapeyron equation, which in turn can be derived from the Gibbs–Duhem equation. They are used to explain colligative properties such as melting-point depression by the application of pressure. Henrys law for the solute can be derived from Raoults law for the solvent using chemical potentials. | 7 | Physical Chemistry |
Nucleotide excision repair is one of the main mechanisms used to remove bulky adducts from DNA lesions caused by chemotherapy drugs, environmental mutagens, and most importantly UV radiation. This mechanism functions by releasing a short damage containing oligonucleotide from the DNA site, and then that gap is filled in and repaired by NER. NER recognizes a variety of structurally unrelated DNA lesions due to the flexibility of the mechanism itself, as NER is highly sensitive to changes in the DNA helical structure. Bulky adducts seem to trigger NER. The XPC-RAD23-CETN2 heterotrimer involved with NER has a critical role in DNA lesion recognition. In addition to other general lesions in the genome, UV damaged DNA binding protein complex (UV-DDB) also has an important role in both recognition and repair of UV-induced DNA photolesions.
Mismatch repair (MMR) mechanisms within the cell correct base mispairs that occur during replication using a variety of pathways. It has a high affinity for targeting DNA lesions with specificity, as alternations in base pair stacking that occur at DNA lesion sites affect the helical structure. This is likely one of many signals that triggers MMR. | 1 | Biochemistry |
David Dye is a Professor of Metallurgy at Imperial College London. Dye specialises in fatigue and micromechanics of aerospace and nuclear materials, mainly Ni/Co superalloys, titanium, TWIP steel, and Zirconium alloys. | 8 | Metallurgy |
Nomenclature generally follows the conventions of human nomenclature. Gene symbols generally are italicised, with all letters in uppercase (e.g., NLGN1, for neuroligin1). Protein designations are the same as the gene symbol, but are not italicised; all letters are in uppercase (NLGN1). mRNAs and cDNAs use the same formatting conventions as the gene symbol. | 1 | Biochemistry |
The number of Unleashed Registrants has increased 10 fold since the integration of BIND. As of December 2006 registration fell just short of 10,000. Subscribers to the commercial versions of BOND fall into six general categories; agriculture and food, biotechnology, pharmaceuticals, informatics, materials and other. The biotechnology sector is the largest of these groups, holding 28% of subscriptions. Pharmaceuticals and informatics follow with 22% and 18% respectively. The United States holds the bulk of these subscriptions, 69%. Other countries with access to the commercial versions of BOND include Canada, the United Kingdom, Japan, China, Korea, Germany, France, India and Australia. All of these countries fall below 6% in user share. | 1 | Biochemistry |
Lactams form by copper-catalyzed 1,3-dipolar cycloaddition of alkynes and nitrones in the Kinugasa reaction | 0 | Organic Chemistry |
It is not always possible to unequivocally determine the direction of intensity change, such as is for example the case for highly overlapping signals next to each other and of which the intensity changes in the opposite direction. This is where the off diagonal peaks in the synchronous 2D spectrum are used for:
#if there is a positive cross-peak at (x, y) in the synchronous 2D spectrum, the intensity of the signals at x and y changes in the same direction
#if there is a negative cross-peak at (x, y) in the synchronous 2D spectrum, the intensity of the signals at x and y changes in the opposite direction
As can be seen in the 2D synchronous spectrum on the right, the intensity changes of the peaks at 10 and 30 are related and the intensity of the peak at 10 and 30 changes in the opposite direction (negative cross-peak at (10,30)). The same is true for the peaks at 20 and 40. | 7 | Physical Chemistry |
Portlethen Moss is considered a raised bog, because its general situation is on higher ground, at the edge of the Mounth, a coastal mountain spur of the Grampian Mountains overlooking the North Sea. There are rock outcrops and strewn boulders relict from the glacial age at this site. Elevations within the Portlethen Moss range from approximately 35 to 60 metres above sea level. Formation of this moss has occurred due to extensive sets of depressions in the underlying rock formations of Old Red Sandstone. The entire water composition of the bog thus has been provided by precipitation with no source of surface runoff, since the topography reduces to lower elevations in every direction. Due to the high winds, moderate precipitation and cool temperatures that generally prevail, conditions are favourable for formation of an acid bog, since water stagnates, but eventually evaporates with ensuing acidity enhancement of decaying organic matter. There was virtually no drainage outlet in prehistoric times, and little drainage even in modern times. | 2 | Environmental Chemistry |
A method of producing oleum sulphuris per campanam, or "oil of sulfur by the bell", was known by the 16th century: it involved burning sulfur under a glass bell in moist weather (or, later, under a moistened bell). However, it was very inefficient (according to Gesner, of sulfur converted into less than of acid), and the resulting product was contaminated by sulfurous acid (or rather, solution of sulfur dioxide) so most alchemists (including, for example, Isaac Newton) didn't consider it equivalent with the "oil of vitriol".
In the 17th century, Johann Glauber discovered that adding saltpeter (potassium nitrate, ) significantly improves the output, also replacing moisture with steam. As saltpeter decomposes, it oxidizes the sulfur to , which combines with water to produce sulfuric acid. In 1736, Joshua Ward, a London pharmacist, used this method to begin the first large-scale production of sulfuric acid. | 7 | Physical Chemistry |
The mechanical bond can reduce the kinetic reactivity of the products, this is ascribed to the increased steric hindrance. Because of this effect hydrogenation of an alkene on the thread of a rotaxane is significantly slower as compared to the equivalent non interlocked thread. This effect has allowed for the isolation of otherwise reactive intermediates.
The ability to alter reactivity without altering covalent structure has led to MIMAs being investigated for a number of technological applications. | 6 | Supramolecular Chemistry |
The resorcinarenes are typically prepared by condensation of resorcinol and an aldehyde in acid solution. This reaction was first described by Adolf von Baeyer who described the condensation of resorcinol and benzaldehyde but was unable to elucidate the nature of the product(s). The methods have since been refined. Recrystallization typically gives the desired isomer in quite pure form. However, for certain aldehydes, the reaction conditions lead to significant by-products. Alternative condensation conditions have been developed, including the use of Lewis acid catalysts.
A green chemistry procedure uses solvent-free conditions: resorcinol, an aldehyde, and p-toluenesulfonic acid are ground together in a mortar and pestle at low temperature. | 6 | Supramolecular Chemistry |
The need to use two compressors in a booster set-up tends to increase the cost of a refrigeration system. A two staged system also needs synchronization, pressure control and lubrication. To reduce these costs, specialized equipment has been developed.
Economizer screw compressors are built by several manufacturers like Refcomp, Mycom, Bitzer and York. These machines merge both compressors of a two staged system into one screw compressor with two inputs: the main suction and an interstage side entrance for higher pressure gas. This means there is no need to install two compressors and still benefit from the booster concept.
There are two types of economizer setups for these compressors, flash and subcooling. The latter works like a two staged booster with subcooling. The flash economizer is different because it doesn't use a heat exchanger to produce the subcooling. Instead, it has a flash chamber or tank, in which flash gas is produced to lower the temperature of the liquid before the expansion. The flash gas that is produced in this tank leaves the liquid line and goes to the economizer entrance of the screw compressor. | 7 | Physical Chemistry |
Compared to redox flow batteries that are inorganic, such as vanadium redox flow batteries and Zn-Br2 batteries, which have been developed for decades, organic redox flow batteries emerged in 2009. The primary appeal of organic redox flow batteries lies in the tunable redox properties of the active components. As of 2021, organic RFB experience low durability (i.e. calendar or cycle life, or both). For this reason, only inorganic RFB have been demonstrated on a commercial scale.
Organic redox flow batteries can be further classified into aqueous (AORFBs) and non-aqueous (NAORFBs). AORFBs use water as solvent for electrolyte materials while NAORFBs employ organic solvents. AORFBs and NAORFBs can be further divided into total and hybrid organic systems. The former use only organic electrode materials, while the latter use inorganic materials for anode or cathode. In larger-scale energy storage, lower solvent cost and higher conductivity give AORFBs greater commercial potential, as well as offering safety advantages from water-based electrolytes. NAORFBs instead provide a much larger voltage window and occupy less physical space. | 7 | Physical Chemistry |
Nickel can be titrated thermometrically using di-sodium dimethylglyoximate as titrant. The chemistry is analogous to the classic gravimetric procedure, but the time taken for a determination can be reduced from many hours to a few minutes. Potential interferences need to be considered. | 3 | Analytical Chemistry |
Normally the y-axis is pressure ratio (P/P), where P is stagnation (or total head) pressure.
ΔT/T (or similar), where T is stagnation (or total head) temperature, is also used. | 7 | Physical Chemistry |
In chemical thermodynamics, an endergonic reaction (; also called a heat absorbing nonspontaneous reaction or an unfavorable reaction) is a chemical reaction in which the standard change in free energy is positive, and an additional driving force is needed to perform this reaction. In layman's terms, the total amount of useful energy is negative (it takes more energy to start the reaction than what is received out of it) so the total energy is a net negative result, as opposed to a net positive result in an exergonic reaction. Another way to phrase this is that useful energy must be absorbed from the surroundings into the workable system for the reaction to happen.
Under constant temperature and constant pressure conditions, this means that the change in the standard Gibbs free energy would be positive,
for the reaction at standard state (i.e. at standard pressure (1 bar), and standard concentrations (1 molar) of all the reagents).
In metabolism, an endergonic process is anabolic, meaning that energy is stored; in many such anabolic processes, energy is supplied by coupling the reaction to adenosine triphosphate (ATP) and consequently resulting in a high energy, negatively charged organic phosphate and positive adenosine diphosphate. | 7 | Physical Chemistry |
2-dimensional semiconductors such as Molybdenum disulfide| are actively researched as potential photocatalysts. | 5 | Photochemistry |
The President of the United States is authorized to declare each May "Steelmark Month" to recognize the contribution made by the steel industry to the United States. | 8 | Metallurgy |
A widely studied class are photochromic compounds which are able to switch between electronic configurations when irradiated by light of a specific wavelength. Each state has a specific absorption maximum which can then be read out by UV-VIS spectroscopy. Members of this class include azobenzenes, diarylethenes, dithienylethenes, fulgides, stilbenes, spiropyrans and phenoxynaphthacene quinones.
Chiroptical molecular switches are a specific subgroup with photochemical switching taking place between an enantiomeric pairs. In these compounds the readout is by circular dichroism rather than by ordinary spectroscopy. Hindered alkenes such as the one depicted below change their helicity (see: planar chirality) as response to irradiation with right or left-handed circularly polarized light
Chiroptical molecular switches that show directional motion are considered synthetic molecular motors: When attached to the end of a helical poly (isocyanate) polymer, they can switch the helical sense of the polymer. | 6 | Supramolecular Chemistry |
Maintenance respiration in plants refers to the amount of cellular respiration, measured by the carbon dioxide (CO) released or oxygen (O) consumed, during the generation of usable energy (mainly ATP, NADPH, and NADH) and metabolic intermediates used for (i) resynthesis of compounds that undergo renewal (turnover) in the normal process of metabolism (examples are enzymatic proteins, ribonucleic acids, and membrane lipids); (ii) maintenance of chemical gradients of ions and metabolites across cellular membranes that are necessary for cellular integrity and plant health; and (iii) operation of metabolic processes involved in physiological adjustment (i.e., acclimation) to a change in the plant's environment. The metabolic costs of the repair of injury from biotic or abiotic stress may also be considered a part of maintenance respiration.
Maintenance respiration is essential for biological health and growth of plants. It is estimated that about half of the respiration carried out by terrestrial plants during their lifetime is for the support of maintenance processes. Because typically more than half of global terrestrial plant photosynthesis (or gross primary production) is used for plant respiration, more than one quarter of global terrestrial plant photosynthesis is presumably consumed in maintenance respiration.
Maintenance respiration is a key component of most physiologically based mathematical models of plant growth, including models of crop growth and yield and models of ecosystem primary production and carbon balance. | 1 | Biochemistry |
The Voigt profile is normalized:
since it is a convolution of normalized profiles. The Lorentzian profile has no moments (other than the zeroth), and so the moment-generating function for the Cauchy distribution is not defined. It follows that the Voigt profile will not have a moment-generating function either, but the characteristic function for the Cauchy distribution is well defined, as is the characteristic function for the normal distribution. The characteristic function for the (centered) Voigt profile will then be the product of the two:
Since normal distributions and Cauchy distributions are stable distributions, they are each closed under convolution (up to change of scale), and it follows that the Voigt distributions are also closed under convolution. | 7 | Physical Chemistry |
Lower pH and lower applied redox potential facilitate the evolution and the enrichment of hydrogen during the process of SCC, thus increasing the SCC intensity.
* Certain austenitic stainless steels and aluminium alloys crack in the presence of chlorides. This limits the usefulness of austenitic stainless steel for containing water with higher than a few parts per million content of chlorides at temperatures above ;
* mild steel cracks in the presence of alkali (e.g. boiler cracking and caustic stress corrosion cracking) and nitrates;
* copper alloys crack in ammoniacal solutions (season cracking);
* high-tensile steels have been known to crack in an unexpectedly brittle manner in a whole variety of aqueous environments, especially when chlorides are present.
With the possible exception of the latter, which is a special example of hydrogen cracking, all the others display the phenomenon of subcritical crack growth, i.e. small surface flaws propagate (usually smoothly) under conditions where fracture mechanics predicts that failure should not occur. That is, in the presence of a corrodent, cracks develop and propagate well below critical stress intensity factor (). The subcritical value of the stress intensity, designated as , may be less than 1% of . | 8 | Metallurgy |
Typically in MRS a single spectrum is acquired by averaging enough spectra over a long acquisition time. Averaging is necessary because of the complex spectral structures and relatively low concentrations of many brain metabolites, which result in a low signal-to-noise ratio (SNR) in MRS of a living brain.
fMRS differs from MRS by acquiring not one but multiple spectra at different time points while the participant is inside the MRI scanner. Thus, temporal resolution is very important and acquisition times need to be kept adequately short to provide a dynamic rate of metabolite concentration change.
To balance the need for temporal resolution and sufficient SNR, fMRS requires a high magnetic field strength (1.5 T and above). High field strengths have the advantage of increased SNR as well as improved spectral resolution allowing to detect more metabolites and more detailed metabolite dynamics.
fMRS is continuously advancing as stronger magnets become more available and better data acquisition techniques are developed providing increased spectral and temporal resolution. With 7-tesla magnet scanners it is possible to detect around 18 different metabolites of H spectrum which is a significant improvement over less powerful magnets. Temporal resolution has increased from 7 minutes in the first fMRS studies to 5 seconds in more recent ones. | 7 | Physical Chemistry |
Herbert C. Brown did not believe that it was necessary to invoke a new type of bonding in stable intermediates to explain the interesting reactivity of the 2-norbornyl cation. Criticizing many chemists for disregarding past explanations of reactivity, Brown argued that all of the aforementioned information about the 2-norbornyl cation could be explained using simple steric effects present in the norbornyl system. Given that an alternative explanation using a rapidly equilibrating pair of ions for describing the 2-norbornyl cation was valid, he saw no need to invoke a stable, non-classical depiction of bonding. Invoking stable non-classical ions was becoming commonplace; Brown felt that this was not only unwarranted but also counterproductive for the field of chemistry as a whole. Indeed, many papers reporting stable non-classical ions were later retracted for being unrealistic or incorrect. After publishing this controversial view in 1962, Brown began a quest to find experimental evidence incompatible with the delocalized picture of bonding in the 2-norbornyl cation.
Brown also worked to prove the instability of a delocalized electronic structure for the 2-norbornyl cation. If the non-classical ion could be proven to be higher in energy than the corresponding classical ion pair, the non-classical ion would only be seen as a transition state between the two asymmetric cations. Though he did not rule out the possibility of a delocalized transition state Brown continued to reject the proposed reflectional symmetry of the 2-norbornyl cation, even late in his career. | 7 | Physical Chemistry |
An aerosol is a suspension of fine solid particles or liquid droplets in air or another gas. Aerosols can be generated from natural or human causes. The term aerosol commonly refers to the mixture of particulates in air, and not to the particulate matter alone. Examples of natural aerosols are fog, mist or dust. Examples of human caused aerosols include particulate air pollutants, mist from the discharge at hydroelectric dams, irrigation mist, perfume from atomizers, smoke, dust, sprayed pesticides, and medical treatments for respiratory illnesses.
The liquid or solid particles in an aerosol have diameters typically less than 1 μm. Larger particles with a significant settling speed make the mixture a suspension, but the distinction is not clear. In everyday language, aerosol often refers to a dispensing system that delivers a consumer product from a spray can.
Diseases can spread by means of small droplets in the breath, sometimes called bioaerosols. | 7 | Physical Chemistry |
Within a long region of genomic sequence, genes are often characterised by having a higher GC-content in contrast to the background GC-content for the entire genome. There is evidence that the length of the coding region of a gene is directly proportional to higher G+C content. This has been pointed to the fact that the stop codon has a bias towards A and T nucleotides, and, thus, the shorter the sequence the higher the AT bias.
Comparison of more than 1,000 orthologous genes in mammals showed marked within-genome variations of the third-codon position GC content, with a range from less than 30% to more than 80%. | 1 | Biochemistry |
Conjugation in Mycobacteria smegmatis, like conjugation in E. coli, requires stable and extended contact between a donor and a recipient strain, is DNase resistant, and the transferred DNA is incorporated into the recipient chromosome by homologous recombination. However, unlike E. coli Hfr conjugation, mycobacterial conjugation is chromosome rather than plasmid based. Furthermore, in contrast to E. coli Hfr conjugation, in M. smegmatis all regions of the chromosome are transferred with comparable efficiencies. The lengths of the donor segments vary widely, but have an average length of 44.2kb. Since a mean of 13 tracts are transferred, the average total of transferred DNA per genome is 575kb. This process is referred to as "Distributive conjugal transfer." Gray et al. found substantial blending of the parental genomes as a result of conjugation and regarded this blending as reminiscent of that seen in the meiotic products of sexual reproduction. | 1 | Biochemistry |
Sulfur has long been known to contribute to damage. This is true for many materials such as metal corrosion, or concrete degradation. In King Lear, Shakespeare says: | 8 | Metallurgy |
C-myc mRNA is a type of mRNA that serves as a template for the MYC protein which is implicated in the rapid growth of cancer cells. This mRNA is a topic of ongoing research to investigate the viability of preventing cancer growth by cleaving or degrading the c-myc mRNA. | 1 | Biochemistry |
In planning the synthesis of phenylacetic acid, two synthons are identified: a nucleophilic "COOH" group, and an electrophilic "PhCH" group. Of course, both synthons do not exist by themselves; synthetic equivalents corresponding to the synthons are reacted to produce the desired reactant. In this case, the cyanide anion is the synthetic equivalent for the COOH synthon, while benzyl bromide is the synthetic equivalent for the benzyl synthon.
The synthesis of phenylacetic acid determined by retrosynthetic analysis is thus:
where Ph stands for phenyl.
* C2 synthons - acetylene, acetaldehyde
* -CHOH synthon - ethylene oxide
* carbocation synthons - alkyl halides
* carbanion synthons - Grignard reagents, organolithiums, substituted acetylides | 0 | Organic Chemistry |
It is known that ribosomes pause at distinct sites, but the reasons for these pauses are mostly unknown. Also, the ribosome pauses if the pseudoknot is disrupted. 10% of the ribosome pauses at the pseudoknot and 4% of the ribosomes are terminated. Before the ribosome is obstructed it passes the pseudoknot. An assay was put together by a group from the University of California in an effort to show a model of mRNA. The translation was monitored in two in vitro systems. It was found that translating ribosomes arent uniformly distributed along an mRNA. Protein folding in vivo is also important and is related to protein synthesis. For finding the location of the ribosomal pause in vivo, the methods that have been used to find the ribosomal pause in vitro can be changed to find these specific locations in vivo.' | 1 | Biochemistry |
The antenna-shaped light harvesting complex of cyanobacteria, glaucocystophyta, and red algae is known as the phycobilisome which is composed of linear tetrapyrrole pigments. Pigment-protein complexes referred to as R-phycoerythrin are rod-like in shape and make up the rods and core of the phycobilisome. Little light reaches algae that reside at a depth of one meter or more in seawater, as light is absorbed by seawater. The pigments, such as phycocyanobilin and phycoerythrobilin, are the chromophores that bind through a covalent thioether bond to their apoproteins at cysteins residues. The apoprotein with its chromophore is called phycocyanin, phycoerythrin, and allophycocyanin, respectively. They often occur as hexamers of α and β subunits (αβ). They enhance the amount and spectral window of light absorption and fill the "green gap", which occur in higher Plants.
The geometrical arrangement of a phycobilisome is very elegant and results in 95% efficiency of energy transfer. There is a central core of allophycocyanin, which sits above a photosynthetic reaction center. There are phycocyanin and phycoerythrin subunits that radiate out from this center like thin tubes. This increases the surface area of the absorbing section and helps focus and concentrate light energy down into the reaction center to a Chlorophyll. The energy transfer from excited electrons absorbed by pigments in the phycoerythrin subunits at the periphery of these antennas appears at the reaction center in less than 100 ps. | 5 | Photochemistry |
mEosFP is another monomeric Eos variant that folds effectively at 37 degrees Celsius. Where tdEos (tandem dimer) cannot fuse to targets such as histones, tubulin, intermediate filaments and gap junctions, and mEos (monomeric) which can only be used successfully at 30 degrees Celsius, mEos2 is an engineered variant that can fold effectively at 37 degrees Celsius and successfully label targets intolerant to fusion from other fluorescent protein dimers . mEos2 shows almost identical spectral properties, brightness, pKa, photoconversion, contrast and maturation properties to WT Eos. The localization precision of mEos2 is twice as great as other monomeric fluorescent proteins. | 1 | Biochemistry |
It is however poorly soluble in solvents other than ammonia. Its use has been superseded by the related reagents sodium hydride, sodium bis(trimethylsilyl)amide (NaHMDS), and lithium diisopropylamide (LDA). | 0 | Organic Chemistry |
Sintering is part of the firing process used in the manufacture of pottery and other ceramic objects. Sintering and vitrification (which requires higher temperatures) are the two main mechanisms behind the strength and stability of ceramics. Sintered ceramic objects are made from substances such as glass, alumina, zirconia, silica, magnesia, lime, beryllium oxide, and ferric oxide. Some ceramic raw materials have a lower affinity for water and a lower plasticity index than clay, requiring organic additives in the stages before sintering.
Sintering begins when sufficient temperatures have been reached to mobilize the active elements in the ceramic material, which can start below their melting point (typically at 50–80% of their melting point), e.g. as premelting. When sufficient sintering has taken place, the ceramic body will no longer break down in water; additional sintering can reduce the porosity of the ceramic, increase the bond area between ceramic particles, and increase the material strength.
Industrial procedures to create ceramic objects via sintering of powders generally include:
* mixing water, binder, deflocculant, and unfired ceramic powder to form a slurry
*spray-drying the slurry
* putting the spray dried powder into a mold and pressing it to form a green body (an unsintered ceramic item)
* heating the green body at low temperature to burn off the binder
* sintering at a high temperature to fuse the ceramic particles together.
All the characteristic temperatures associated with phase transformation, glass transitions, and melting points, occurring during a sinterisation cycle of a particular ceramic's formulation (i.e., tails and frits) can be easily obtained by observing the expansion-temperature curves during optical dilatometer thermal analysis. In fact, sinterisation is associated with a remarkable shrinkage of the material because glass phases flow once their transition temperature is reached, and start consolidating the powdery structure and considerably reducing the porosity of the material.
Sintering is performed at high temperature. Additionally, a second and/or third external force (such as pressure, electric current) could be used. A commonly used second external force is pressure. Sintering performed by only heating is generally termed "pressureless sintering", which is possible with graded metal-ceramic composites, utilising a nanoparticle sintering aid and bulk molding technology. A variant used for 3D shapes is called hot isostatic pressing.
To allow efficient stacking of product in the furnace during sintering and to prevent parts sticking together, many manufacturers separate ware using ceramic powder separator sheets. These sheets are available in various materials such as alumina, zirconia and magnesia. They are additionally categorized by fine, medium and coarse particle sizes. By matching the material and particle size to the ware being sintered, surface damage and contamination can be reduced while maximizing furnace loading. | 8 | Metallurgy |
Cryptophytes, or cryptomonads are a group of algae that contain a red-algal derived chloroplast. Cryptophyte chloroplasts contain a nucleomorph that superficially resembles that of the chlorarachniophytes. Cryptophyte chloroplasts have four membranes, the outermost of which is continuous with the rough endoplasmic reticulum. They synthesize ordinary starch, which is stored in granules found in the periplastid space—outside the original double membrane, in the place that corresponds to the red alga's cytoplasm. Inside cryptophyte chloroplasts is a pyrenoid and thylakoids in stacks of two.
Their chloroplasts do not have phycobilisomes, but they do have phycobilin pigments which they keep in their thylakoid space, rather than anchored on the outside of their thylakoid membranes.
Cryptophytes may have played a key role in the spreading of red algal based chloroplasts. | 5 | Photochemistry |
These plots were first introduced in a 1970 paper by R. A. More O’Ferrall to discuss mechanisms of β-eliminations and later adopted by W. P. Jencks in an attempt to clarify the finer details involved in the general acid-base catalysis of reversible addition reactions to carbon electrophiles such as the hydration of carbonyls. | 7 | Physical Chemistry |
*[http://www.arabianbusiness.com/mohammad-baloola-interview-beating-bulge-446743.html Mohammad Baloola interview: Beating the bulge – Arabian Business Magazine]
*[http://gulfnews.com/news/gulf/uae/education/diabetes-invention-inches-closer-to-development-1.942614 Diabetes invention inches closer to development – Gulf New Newspaper]
*[http://gulfnews.com/news/gulf/uae/education/graduate-invents-winning-diabetes-device-1.789567 Graduate invents winning diabetes device – Gulf New Newspaper]
*[http://gulftoday.ae/portal/c4302645-fb9d-44bf-8327-95ca2a5554cf.aspx Former AUST pupil in Arab elite-Gulf Today Newspaper] | 7 | Physical Chemistry |
Ferrophosphorus is a ferroalloy, an alloy of iron and phosphorus. It contains high proportion of iron phosphides, FeP and FeP. Its CAS number is 8049-19-2. The usual grades contain either 18 or 25% of phosphorus. It is a gray solid material with melting point between 1050-1100 °C. It may liberate phosphine in contact with water. Very fine powder can be combustible.
Ferrophosphorus is used in metallurgy as a source of phosphorus for alloying, for deoxidizing the melt and for removal of unwanted compounds into slag.
Ferrophosphorus is a byproduct of phosphorus production in submerged-arc furnaces from apatites, by their reduction with carbon. It is formed from the iron oxide impurities.
Addition of ferrophosphorus is used to produce powder metallurgy (P/M) steels with favorable magnetic properties, e.g. high saturation induction. Iron phosphide acts here as a solid solution hardener and a sintering aid. Usually about 0.45 w/o of phosphorus is added to iron; higher amount can improve magnetic properties but at above about 0.8 w/o the process parameters have to be too tightly controlled to prevent phosphorus segregation on grain boundaries and resulting excessive brittleness.
Ferrophosphorus can be added to cast iron, where the phosphorus improves fluidity and therefore quality of the castings, can increase wear resistance and cutability. In steels its addition to some alloys can improve corrosion resistance.
Ferrophosphorus can be used as a construction aggregate for production of high-density concrete for radiation shielding, as an alternative to usually used steel punchings and shot. It can be used with both Portland cement and magnesia cement.
Ferrophosphorus, reacted with sulfur or pyrite, is used for production of phosphorus pentasulfide.
Ferrophosphorus can be used for production of lithium iron phosphate, necessary as electrode material for LiFePO4 batteries.
Ferrophosphorus can be used instead of zinc powder in some paints and coatings. It has good adhesion, anticorrosive properties, electrical and thermal conductivity, and wear resistance.
Ferrophosphorus can be used as a reducing agent to produce sodium or potassium from sodium carbonate or potassium carbonate. | 8 | Metallurgy |
Winifred Burks-Houck (August 20, 1950 – May 6, 2004) was an environmental organic chemist and the first female president of National Organization for the Professional Advancement of Black Chemists and Chemical Engineers (NOBCChE), serving from 1993 – 2001. | 0 | Organic Chemistry |
The original agromineral is potash, it is how chemical fertilizers get it potassium and phosphorus nutrients in the present day. Due to such a high demand, the ore is running in low supply which has increased its market value. The biggest limiting factor is potassium, despite being the fourth most abundant element in the Earth's crust it has only one major source that being potash. One of the popular alternative ideas to get away from the use of chemical fertilizer is spreading rock powders in the field as a source of nutrients. One of the major research areas involve looking feldspars and feldspathoids and determining which would more efficient to use. In one of the studies it showed that the feldspathoid nepheline had a much higher dissolution rate making it more efficient source of potassium than other rocks that are much more potassium-rich like granitic rocks.
There is a push to move away from chemical fertilizers since it has been connected to groundwater pollution. There has been a shift into looking at grinding rocks into a powder that can be incorporated into the ground as a new way to add nutrients to the soil. The idea behind rock powder originated from the idea that rock weather and is how nutrients were originally put in the soil; the soil is weathered rock. With this concept it has been determined that the rock source is very important because the rock can have unwanted elements that can be toxic for both the plant and the humans ingesting it. Research has been done on rocks such as basalt and dacite; each rock had their pros and cons. The success of the rock powder can be affected by crop cycle. For example, basalt was effective when it came to long-cycle crops, but short-cycle crops it was not as effective as chemical fertilizers. With some rock powders it can take anywhere between 1-5 years to show results. The biggest contributions to rocks being an effective rock powder comes down to mineralogy and chemical composition. Once rock sources that have the proper elements and effectiveness is found, the limitation to rock powders then becomes how it is ground. Grinding a mineral, like olivine, to a particle size that would be effective in the ground (1μm), takes about 1.5 gigajoules per ton of rock. Research will be needed to find more efficient ways to crush rock for rock-powders to be a sustainable solution for replenishing plant nutrients. | 9 | Geochemistry |
While phases of matter are traditionally defined for systems in thermal equilibrium, work on quantum many-body localized (MBL) systems has provided a framework for defining phases out of equilibrium. MBL phases never reach thermal equilibrium, and can allow for new forms of order disallowed in equilibrium via a phenomenon known as localization protected quantum order. The transitions between different MBL phases and between MBL and thermalizing phases are novel dynamical phase transitions whose properties are active areas of research. | 7 | Physical Chemistry |
The first paper describing TILLING used HPLC to identify mutations (McCallum et al., 2000a). The method was made more high throughput by using the restriction enzyme Cel-I combined with the LICOR gel based system to identify mutations (Colbert et al.,2001). Advantages to using this system are that mutation sites can be easily confirmed and differentiated from noise. This is because different colored dyes can be used for the forward and reverse primers. Once the cleavage products have been run on a gel, it can be viewed in separate channels, and much like an RFLP, the fragment sizes within a lane in each channel should add up to the full length product size. Advantages to the LICOR system are separation of large fragments (~ 2kb), high sample throughput (96 samples loaded on paper combs), and freeware to identify the mutations (GelBuddy). Drawbacks to the LICOR system is having to pour slab gels and long run times (~4 hours). TILLING and EcoTILLING methods are now being used on capillary systems from, Advanced Analytical Technologies, ABI and Beckman.
Several systems can be used to separate PCR products that are not labeled with dyes. Simple agarose electrophoresis systems will separate cleavage products inexpensively and with standard lab equipment. This was used to discover SNPs in chum salmon and was referred to as DEcoTILLING. The disadvantage of this system is reduced resolution compared to polyacrylamide systems. Elchrom Scientific sells Spreadex gels which are precast, can be high throughput and are more sensitive than standard polyacrylamide gels. Advanced Analytical Technologies Inc sells the AdvanCE FS96 dsDNA Fluorescent System which is a 96 capillary electrophoresis system that has several advantages over traditional methods; including ability to separate large fragments (up to 40kb), no desalting or precipitation step required, short run times (~30 minutes), sensitivity to 5pg/ul and no need for fluorescent labeled primers. | 1 | Biochemistry |
Ions in crystal lattices of purely ionic compounds are spherical; however, if the positive ion is small and/or highly charged, it will distort the electron cloud of the negative ion, an effect summarised in Fajans' rules. This polarization of the negative ion leads to a build-up of extra charge density between the two nuclei, that is, to partial covalency. Larger negative ions are more easily polarized, but the effect is usually important only when positive ions with charges of 3+ (e.g., Al) are involved. However, 2+ ions (Be) or even 1+ (Li) show some polarizing power because their sizes are so small (e.g., LiI is ionic but has some covalent bonding present). Note that this is not the ionic polarization effect that refers to displacement of ions in the lattice due to the application of an electric field. | 6 | Supramolecular Chemistry |
Molar concentration (also called molarity, amount concentration or substance concentration) is a measure of the concentration of a chemical species, in particular, of a solute in a solution, in terms of amount of substance per unit volume of solution. In chemistry, the most commonly used unit for molarity is the number of moles per liter, having the unit symbol mol/L or mol/dm in SI units. A solution with a concentration of 1 mol/L is said to be 1 molar, commonly designated as 1 M or 1 . Molarity is often depicted with square brackets around the substance of interest; for example, the molarity of the hydrogen ion is depicted as [H]. | 3 | Analytical Chemistry |
* Oral drug delivery: Emulsions may provide an efficient means of administering drugs that are poorly soluble or have low bioavailability or dissolution rates, increasing both dissolution rates and absorption to increase bioavailability and improve bioavailability. By increasing surface area provided by an emulsion, dissolution rates and absorption rates of drugs are increased, improving their bioavailability.
* Topical formulations: Emulsions are widely utilized as bases for topical drug delivery formulations such as creams, lotions and ointments. Their incorporation allows lipophilic as well as hydrophilic drugs to be mixed together for maximum skin penetration and permeation of active ingredients.
* Parenteral drug delivery: Emulsions serve as carriers for intravenous or intramuscular administration of drugs, solubilizing lipophilic ones while protecting from degradation and decreasing injection site irritation. Examples include propofol as a widely used anesthetic and lipid-based solutions used for total parenteral nutrition delivery.
* Ocular Drug Delivery: Emulsions can be used to formulate eye drops and other ocular drug delivery systems, increasing drug retention time in the eye and permeating through corneal barriers more easily while providing sustained release of active ingredients and thus increasing therapeutic efficacy.
* Nasal and Pulmonary Drug Delivery: Emulsions can be an ideal vehicle for creating nasal sprays and inhalable drug products, enhancing drug absorption through nasal and pulmonary mucosa while providing sustained release with reduced local irritation.
* Vaccine Adjuvants: Emulsions can serve as vaccine adjuvants by strengthening immune responses against specific antigens. Emulsions can enhance antigen solubility and uptake by immune cells while simultaneously providing controlled release, amplifying an immunological response and thus amplifying its effect.
* Taste Masking: Emulsions can be used to encase bitter or otherwise unpleasant-tasting drugs, masking their taste and increasing patient compliance - particularly with pediatric formulations.
* Cosmeceuticals: Emulsions are widely utilized in cosmeceuticals products that combine cosmetic and pharmaceutical properties. These emulsions act as carriers for active ingredients like vitamins, antioxidants and skin lightening agents to provide improved skin penetration and increased stability. | 7 | Physical Chemistry |
Supramolecular assembly requires non-covalent interactions directing the formation of 2D polymers by relying on electrostatic interactions such as hydrogen bonding and van der Waals forces. To design artificial assemblies capable of high selectivity requires correct manipulation of energetic and stereochemical features of non-covalent forces. Some benefits of non-covalent interactions is their reversible nature and response to external factors such as temperature and concentration. The mechanism of non-covalent polymerization in supramolecular chemistry is highly dependent on the interactions during the self-assembly process. The degree of polymerization depends highly on temperature and concentration. The mechanisms may be divided into three categories: isodesmic, ring-chain, and cooperative.
One example of isodesmic associations in supramolecular aggregates is seen in Figure 7, (CA*M) cyanuric acid (CA) and melamine (M) interactions and assembly through hydrogen bonding. Hydrogen bonding has been used to guide assembly of molecules into two-dimensional networks, that can then serve as new surface templates and offer an array of pores of sufficient capacity to accommodate large guest molecules. An example of utilizing surface structures through non-covalent assembly uses adsorbed monolayers to create binding sites for target molecules through hydrogen bonding interactions. Hydrogen bonding is used to guide the assembly of two different molecules into a 2D honeycomb porous network under ultra high vacuum seen in figure 8. 2D polymers based on DNA have been reported | 7 | Physical Chemistry |
The phosphatome includes proteins that are structurally closely related to phosphatases but lack catalytic activity. These retain biological function, and may regulate pathways that involve active phosphatases, or bind to phosphorylated substrates without cleaving them. Examples include [https://www.ncbi.nlm.nih.gov/gene/6815 STYX], where the phosphatase domain has become a phospho-tyrosine binding domain, and [https://www.ncbi.nlm.nih.gov/gene/2580 GAK], whose inactive phosphatase domain instead binds phospholipids. | 1 | Biochemistry |
The structure of SAMs is also dependent on the curvature of the substrate. SAMs on nanoparticles, including colloids and nanocrystals, "stabilize the reactive surface of the particle and present organic functional groups at the particle-solvent interface". These organic functional groups are useful for applications, such as immunoassays or sensors, that are dependent on chemical composition of the surface. | 6 | Supramolecular Chemistry |
Dynamic vapor sorption (DVS) is a gravimetric technique that measures how quickly and how much of a solvent is absorbed by a sample such as a dry powder absorbing water. It does this by varying the vapor concentration surrounding the sample and measuring the change in mass which this produces. The technique is mostly used for water vapor, but is suitable for a wide range of organic solvents.
Daryl Williams, founder of Surface Measurement Systems Ltd, developed Dynamic Vapor Sorption in 1991; the first instrument was delivered to Pfizer UK in 1992. DVS was originally developed to replace the time and labor-intensive desiccators and saturated salt solutions used to measure water vapor sorption isotherms. | 7 | Physical Chemistry |
Organic matter is common throughout the ecosystem and is cycled through decomposition processes by soil microbial communities that are crucial for nutrient availability. After degrading and reacting, it can move into soil and mainstream water via waterflow. Organic matter provides nutrition to living organisms. Organic matter acts as a buffer in aqueous solution to maintain a neutral pH in the environment. The buffer acting component has been proposed to be relevant for neutralizing acid rain. | 0 | Organic Chemistry |
The visual cycle is a circular enzymatic pathway, which is the front-end of phototransduction. It regenerates 11-cis-retinal. For example, the visual cycle of mammalian rod cells is as follows:
#all-trans-retinyl ester + HO → 11-cis-retinol + fatty acid; RPE65 isomerohydrolases;
#11-cis-retinol + NAD → 11-cis-retinal + NADH + H; 11-cis-retinol dehydrogenases;
#11-cis-retinal + aporhodopsin → rhodopsin + HO; forms Schiff base linkage to lysine, -CH=NH-;
#rhodopsin + hν → metarhodopsin II (i.e., 11-cis photoisomerizes to all-trans):
#:(rhodopsin + hν → photorhodopsin → bathorhodopsin → lumirhodopsin → metarhodopsin I → metarhodopsin II);
#metarhodopsin II + HO → aporhodopsin + all-trans-retinal;
#all-trans-retinal + NADPH + H → all-trans-retinol + NADP; all-trans-retinol dehydrogenases;
#all-trans-retinol + fatty acid → all-trans-retinyl ester + HO; lecithin retinol acyltransferases (LRATs).
Steps 3, 4, 5, and 6 occur in rod cell outer segments; Steps 1, 2, and 7 occur in retinal pigment epithelium (RPE) cells.
RPE65 isomerohydrolases are homologous with beta-carotene monooxygenases; the homologous ninaB enzyme in Drosophila has both retinal-forming carotenoid-oxygenase activity and all-trans to 11-cis isomerase activity. | 1 | Biochemistry |
Neurturin is encoded for by the NRTN gene located on chromosome 19 in humans and has been shown to promote potent effects on survival and function of developing and mature midbrain dopaminergic neurons (DA) in vitro. In vivo the direct administration of neurturin into substantia nigra of mice models also shows mature DA neuron protection. In addition, neurturin has also been shown to support the survival of several other neurons including sympathetic and sensory neurons of the dorsal root ganglia. Knockout mice have shown that neurturin does not appear essential for survival. However, evidence shows retarded growth of enteric, sensory and parasympathetic neurons in mice upon the removal of neurturin receptors. | 1 | Biochemistry |
Enhancer RNAs (eRNAs) represent a class of relatively long non-coding RNA molecules (50-2000 nucleotides) transcribed from the DNA sequence of enhancer regions. They were first detected in 2010 through the use of genome-wide techniques such as RNA-seq and ChIP-seq. eRNAs can be subdivided into two main classes: 1D eRNAs and 2D eRNAs, which differ primarily in terms of their size, polyadenylation state, and transcriptional directionality. The expression of a given eRNA correlates with the activity of its corresponding enhancer in target genes. Increasing evidence suggests that eRNAs actively play a role in transcriptional regulation in cis and in trans, and while their mechanisms of action remain unclear, a few models have been proposed. | 1 | Biochemistry |
The bacterial flagellar motor has been proposed to follow a dissipative allosteric model, where ultrasensitivity comes as a combination of protein binding affinity and energy contributions from the proton motive force (see Flagellar motors and chemotaxis below). | 1 | Biochemistry |
Melainabacteria have been found to potentially play a role in digesting fiber in the human gut, and are more commonly in herbivorous mammals and those with plant-rich diets. Because plant diets require more fiber break-down, Melainabacteria may aid in this digestive function. However, scientists are unsure of why these microbes are in the gut and how they got there. Ongoing studies such as, "The human gut and groundwater harbor non-photosynthetic bacteria belonging to a new candidate phylum sibling to Cyanobacteria," funded by various organizations such as the National Institutes of Health, the David and Lucile Packard Foundation, The Hartwell Foundation, the Arnold and Mabel Beckman Foundation, the U.S. Department of Energy, the European Molecular Biology Organization and the Wellcome Trust. | 2 | Environmental Chemistry |
Composite materials contain two or more macroscopic phases, one of which is often ceramic. For example, a continuous matrix, and a dispersed phase of ceramic particles or fibers.
Applications of composite materials range from structural elements such as steel-reinforced concrete, to the thermally insulative tiles that play a key and integral role in NASAs Space Shuttle thermal protection system, which is used to protect the surface of the shuttle from the heat of re-entry into the Earths atmosphere. One example is Reinforced Carbon-Carbon (RCC), the light gray material that withstands reentry temperatures up to 1510 °C (2750 °F) and protects the nose cap and leading edges of Space Shuttle's wings. RCC is a laminated composite material made from graphite rayon cloth and impregnated with a phenolic resin. After curing at high temperature in an autoclave, the laminate is pyrolized to convert the resin to carbon, impregnated with furfural alcohol in a vacuum chamber, and cured/pyrolized to convert the furfural alcohol to carbon. In order to provide oxidation resistance for reuse capability, the outer layers of the RCC are converted to silicon carbide.
Domestic examples of composites can be seen in the "plastic" casings of television sets, cell-phones and so on. These plastic casings are usually a composite made up of a thermoplastic matrix such as acrylonitrile butadiene styrene (ABS) in which calcium carbonate chalk, talc, glass fibers or carbon fibers have been added for strength, bulk, or electro-static dispersion. These additions may be referred to as reinforcing fibers, or dispersants, depending on their purpose.
Thus, the matrix material surrounds and supports the reinforcement materials by maintaining their relative positions. The reinforcements impart their special mechanical and physical properties to enhance the matrix properties. A synergism produces material properties unavailable from the individual constituent materials, while the wide variety of matrix and strengthening materials provides the designer with the choice of an optimum combination. | 7 | Physical Chemistry |
Let q = (q, q, q) and p = (p, p, p) denote the position vector and momentum vector of a particle of an ideal gas, respectively. Let F denote the net force on that particle. Then (two times) the time-averaged kinetic energy of the particle is:
where the first equality is Newtons second law, and the second line uses Hamiltons equations and the equipartition theorem. Summing over a system of N particles yields
By Newtons third law and the ideal gas assumption, the net force of the system is the force applied by the walls of the container, and this force is given by the pressure P' of the gas. Hence
where dS is the infinitesimal area element along the walls of the container. Since the divergence of the position vector q is
the divergence theorem implies that
where dV is an infinitesimal volume within the container and V is the total volume of the container.
Putting these equalities together yields
which immediately implies the ideal gas law for N particles:
where n = N/N is the number of moles of gas and R = Nk is the gas constant. | 7 | Physical Chemistry |
When the motion is slow (in biology, for example, diffusion in a membrane), getting adequate statistics from a single-point FCS experiment may take a prohibitively long time. More data can be obtained by performing the experiment in multiple spatial points in parallel, using a laser scanning confocal microscope. This approach has been called Image Correlation Spectroscopy (ICS). The measurements can then be averaged together.
Another variation of ICS performs a spatial autocorrelation on images, which gives information about the concentration of particles. The correlation is then averaged in time. While camera white noise does not autocorrelate over time, it does over space - this creates a white noise amplitude in the spatial autocorrelation function which must be accounted for when fitting the autocorrelation amplitude in order to find the concentration of fluorescent molecules.
A natural extension of the temporal and spatial correlation versions is spatio-temporal ICS (STICS). In STICS there is no explicit averaging in space or time (only the averaging inherent in correlation). In systems with non-isotropic motion (e.g. directed flow, asymmetric diffusion), STICS can extract the directional information. A variation that is closely related to STICS (by the Fourier transform) is k-space Image Correlation Spectroscopy (kICS).
There are cross-correlation versions of ICS as well, which can yield the concentration, distribution and dynamics of co-localized fluorescent molecules. Molecules are considered co-localized when individual fluorescence contributions are indistinguishable due to overlapping point-spread functions of fluorescence intensities. | 7 | Physical Chemistry |
The original ICE protocol involved an RT-PCR amplification step and therefore required primers and knowledge of the location or regions to be investigated, alongside a maximum cDNA length of 300–500bp.
The ICE-seq method is complicated, along with being labour-, reagent- and time-intensive. One protocol from 2015 took 22 days. This shares a limitation with inosine-specific cleavage, in that if there are two A-to-I modifications in relatively close proximity, the downstream mod is less likely to be detected since the cDNA synthesis will be truncated at a prior nucleotide.
Both ICE and ICE-seq suffer from a lack of sensitivity to infrequently edited locations: it becomes difficult to distinguish a modification with a frequency of <10% from a false positive. An increase in read depth and quality can increase sensitivity, but also then suffer from further amplification bias. | 1 | Biochemistry |
Actinic lights are also common in the reef aquarium industry. They are used to promote coral and invertebrate growth. They are also used to accentuate the fluorescence of fluorescent fish.
Actinic lighting is also used to limit algae growth in the aquarium. Since algae (like many other plants), flourish in shallower warm water, algae cannot effectively photosynthesize from blue and violet light, thus actinic light minimizes its photosynthetic benefit.
Actinic lighting is also a great alternative to black lights as it provides a "night environment" for the fish, while still allowing enough light for coral and other marine life to grow. Aesthetically, they make fluorescent coral "pop" to the eye, but in some cases also to promote the growth of deeper-water coral adapted to photosynthesis in regions of the ocean dominated by blue light. | 7 | Physical Chemistry |
Berberine bridge enzyme-like (BBE-like enzymes) form a subgroup of the superfamily of FAD-linked oxidases (SCOPe d.58.32), structurally characterized by a typical fold observed initially for vanillyl-alcohol oxidase (VAO). This proteins are part of a multigene family (PF08031) that can be found in plants, fungi and bacteria.
BBE-like enzymes family form a large subgroup that have a special C-terminal structural element adjacent to the substrate binding region. An homonym of this family is the (S)-reticuline oxidase or berberine bridge enzyme from California poppy (Eschscholzia californica), the responsible of catalyzing the conversion of (S)-reticuline to (S)-scoulerine. This conversion is made by an oxidative ring closure reaction. The product of this reaction is the C-C bond and is referred to as the berberine bridge. Also, marks a branch point in the biosynthesis of benzylisoquinoline alkaloids.
As mentioned above, BBE-like enzymes are in the large family of FAD-linked oxidases. Regarding the structure of this particular family, they have a FAD binding module formed by the N- and C- terminal parts of the protein. There is a substrate binding module that, in collaboration with isoalloxazine ring of FAD, disposes the environment for efficient substrate binding and oxidation. | 1 | Biochemistry |
Calculation of reactivity ratios generally involves carrying out several polymerizations at varying monomer ratios. The copolymer composition can be analysed with methods such as Proton nuclear magnetic resonance, Carbon-13 nuclear magnetic resonance, or Fourier transform infrared spectroscopy. The polymerizations are also carried out at low conversions, so monomer concentrations can be assumed to be constant. With all the other parameters in the copolymer equation known, and can be found. | 7 | Physical Chemistry |
After the insertion of Okazaki fragments, the RNA primers are removed (the mechanism of removal differs between prokaryotes and eukaryotes) and replaced with new deoxyribonucleotides that fill the gaps where the RNA primer was present. DNA ligase then joins the fragmented strands together, completing the synthesis of the lagging strand.
In prokaryotes, DNA polymerase I synthesizes the Okazaki fragment until it reaches the previous RNA primer. Then the enzyme simultaneously acts as a 5′→3′ exonuclease, removing primer ribonucleotides in front and adding deoxyribonucleotides behind. Both the activities of polymerization and excision of the RNA primer occur in the 5′→3′ direction, and polymerase I can do these activities simultaneously; this is known as “Nick Translation”. Nick translation refers to the synchronized activity of polymerase I in removing the RNA primer and adding deoxyribonucleotides. Later, a gap between the strands is formed called a nick, which is sealed using a DNA ligase.
In eukaryotes the removal of RNA primers in the lagging strand is essential for the completion of replication. Thus, as the lagging strand being synthesized by DNA polymerase δ in 5′→3′ direction, Okazaki fragments are formed, which are discontinuous strands of DNA. Then, when the DNA polymerase reaches to the 5’ end of the RNA primer from the previous Okazaki fragment, it displaces the 5′ end of the primer into a single-stranded RNA flap which is removed by nuclease cleavage. Cleavage of the RNA flaps involves three methods of primer removal. The first possibility of primer removal is by creating a short flap that is directly removed by flap structure-specific endonuclease 1 (FEN-1), which cleaves the 5’ overhanging flap. This method is known as the short flap pathway of RNA primer removal. The second way to cleave a RNA primer is by degrading the RNA strand using a RNase, in eukaryotes it’s known as the RNase H2. This enzyme degrades most of the annealed RNA primer, except the nucleotides close to the 5’ end of the primer. Thus, the remaining nucleotides are displayed into a flap that is cleaved off using FEN-1. The last possible method of removing RNA primer is known as the long flap pathway. In this pathway several enzymes are recruited to elongate the RNA primer and then cleave it off. The flaps are elongated by a 5’ to 3’ helicase, known as Pif1. After the addition of nucleotides to the flap by Pif1, the long flap is stabilized by the replication protein A (RPA). The RPA-bound DNA inhibits the activity or recruitment of FEN1, as a result another nuclease must be recruited to cleave the flap. This second nuclease is DNA2 nuclease , which has a helicase-nuclease activity, that cleaves the long flap of RNA primer, which then leaves behind a couple of nucleotides that are cleaved by FEN1. At the end, when all the RNA primers have been removed, nicks form between the Okazaki fragments that are filled-in with deoxyribonucleotides using an enzyme known as ligase1, through a process called ligation. | 1 | Biochemistry |
The rotary kilns maximum temperature ranges between 1,230 and 1,260 °C, which significantly exceeds the 1,000 to 1,050 °C threshold for iron oxide reduction. The main objective is to achieve a paste-like consistency of the ore gangue. The reduced iron agglomerates into 3 to 8 mm metal nodules called . If the infusibility of the gangue is high, the temperature must be increased, up to 1,400 °C for a basic charge. It is crucial to control the gangues hot viscosity. Among rotary drum direct reduction processes, it stands out for using high temperatures.
Another distinctive attribute of the procedure involves introducing powdered coal to the furnace outlet. Furthermore, the process has evolved to enable terminating the supply of coal and running exclusively on the coal dust or coke dust introduced with the ore. In this situation, solely combustion air is injected at the furnace outlet. Thermal efficiency is improved in shaft furnaces such as blast furnaces compared to rotary furnaces due to the air absorbing some of the Luppen heat. However, the oxygen in the air partially re-oxidizes the product, meaning that the Luppen is still altered by contact with air at the end or after leaving the furnace, despite complete reduction of iron in the furnace.
The hot assembly is discharged from the furnace and then rapidly cooled and crushed. The iron is separated from the slag via magnetic separation. Magnetically intermediate fines make up 5–15% of the charge. While partial melting of the charge leads to the increased density of the prereducts, it also requires significant energy consumption. | 8 | Metallurgy |
A crystalline solid has been traditionally viewed as a static entity where the movements of its atomic components are limited to its vibrational equilibrium. As seen by the transformation of graphite to diamond, solid to solid transformation can occur under physical or chemical pressure. It has been proposed that the transformation from one crystal arrangement to another occurs in a cooperative manner. Most of these studies have been focused in studying an organic or metal-organic framework. In addition to studies of macromolecular crystalline transformation, there are also studies of single-crystal molecules that can change their conformation in the presence of organic solvents. An organometallic complex has been shown to morph into various orientations depending on whether it is exposed to solvent vapors or not. | 6 | Supramolecular Chemistry |
The main light harvesting complex in Green bacteria is known as the chlorosome. The chlorosome is equipped with rod-like BChl c aggregates with protein embedded lipids surrounding it. Chlorosomes are found outside of the membrane which covers the reaction centre. Green sulphur bacteria and some Chloroflexia use ellipsoidal complexes known as the chlorosome to capture light. Their form of bacteriochlorophyll is green. | 5 | Photochemistry |
Flocculation and sedimentation are widely employed in the purification of drinking water as well as in sewage treatment, storm-water treatment and treatment of industrial wastewater streams. Typical treatment processes consist of grates, coagulation, flocculation, sedimentation, granular filtration and disinfection. As the demand for eco-friendly solutions in the flocculation process continues to grow, biopolymers are emerging as a highly promising solution. Among these, chitosan stands out for its exceptional properties, making it a top contender in this environmentally-conscious endeavor. Chitosan is not only biodegradable but also exhibits a unique ability to bind with a wide range of contaminants, including heavy metals and organic pollutants, effectively removing them from water sources. | 8 | Metallurgy |
When the process needed is more dehumidification or drying, the Cromer cycle can be enhanced by using the free heat available from the condensing side of the reverse Carnot refrigeration cycle. This heat, sometimes called "hot gas bypass" can be added before the desiccant wheel to enhance the drying of the wheel at location 1 of Figure 1 (but after the filter), called pre-heat. Hot gas bypass heat can also be added to the process at location 4, called reheat, which delivers warmer but even lower RH supply air. Either one or both hot gas bypass locations can be used. When a Cromer cycle air conditioning system is enhanced with hot gas bypass, it is typically referred to as "active" Cromer cycle air-conditioning. When the cycle is used as equipment designed for dehumidification or drying, it is typically called a Cromer cycle dehumidifier or Cromer cycle dryer.
R&D magazine recognized the Cromer cycle in 2006 with an R&D 100 Award in the mechanical/materials category, recognizing the year's 100 most significant technological innovations. | 7 | Physical Chemistry |
Copper does not require cleaning or maintenance. It is particularly suited for areas that are difficult or dangerous to access after installation. | 8 | Metallurgy |
Diamines form a wide range of coordination complexes. They typically form 5- and 6-membered chelate rings. Examples of the former include ethylenediamine and 2,2′-bipyridine. Six-membered chelate rings are formed by 1,3-diaminopropane. The bite angle in such complexes is usually near 90°. Longer chain diamines, which are "floppy", tend not to form chelate rings. | 0 | Organic Chemistry |
Plants with CAM must control storage of and its reduction to branched carbohydrates in space and time.
At low temperatures (frequently at night), plants using CAM open their stomata, molecules diffuse into the spongy mesophylls intracellular spaces and then into the cytoplasm. Here, they can meet phosphoenolpyruvate (PEP), which is a phosphorylated triose. During this time, the plants are synthesizing a protein called PEP carboxylase kinase (PEP-C kinase), whose expression can be inhibited by high temperatures (frequently at daylight) and the presence of malate. PEP-C kinase phosphorylates its target enzyme PEP carboxylase (PEP-C). Phosphorylation dramatically enhances the enzymes capability to catalyze the formation of oxaloacetate, which can be subsequently transformed into malate by NAD malate dehydrogenase. Malate is then transported via malate shuttles into the vacuole, where it is converted into the storage form malic acid. In contrast to PEP-C kinase, PEP-C is synthesized all the time but almost inhibited at daylight either by dephosphorylation via PEP-C phosphatase or directly by binding malate. The latter is not possible at low temperatures, since malate is efficiently transported into the vacuole, whereas PEP-C kinase readily inverts dephosphorylation.
In daylight, plants using CAM close their guard cells and discharge malate that is subsequently transported into chloroplasts. There, depending on plant species, it is cleaved into pyruvate and either by malic enzyme or by PEP carboxykinase. is then introduced into the Calvin cycle, a coupled and self-recovering enzyme system, which is used to build branched carbohydrates. The by-product pyruvate can be further degraded in the mitochondrial citric acid cycle, thereby providing additional molecules for the Calvin Cycle. Pyruvate can also be used to recover PEP via pyruvate phosphate dikinase, a high-energy step, which requires ATP and an additional phosphate. During the following cool night, PEP is finally exported into the cytoplasm, where it is involved in fixing carbon dioxide via malate. | 5 | Photochemistry |
This method use DNA recombinant technology and it gives an actual measurement of protein stability. In his detailed site-directed mutagenesis studies, Utani and his coworkers substituted 19 amino acids at Trp49 of the tryptophan synthase and he measured the free energy of unfolding. They found that the increased stability is directly proportional to increase in hydrophobicity up to a certain size limit. The main disadvantage of site-directed mutagenesis method is that not all the 20 naturally occurring amino acids can substitute a single residue in a protein. Moreover, these methods have cost problems and is useful only for measuring protein stability. | 6 | Supramolecular Chemistry |
This family includes TGF-β1, TGF-β2, TGF-β3, and TGF-β5. They are involved in positively and negatively regulation of cell division, the formation of the extracellular matrix between cells, apoptosis, and embryogenesis. They bind to TGF-β type II receptor (TGFBRII).
TGF-β1 stimulates the synthesis of collagen and fibronectin and inhibits the degradation of the extracellular matrix. Ultimately, it increases the production of extracellular matrix by epithelial cells.
TGF-β proteins regulate epithelia by controlling where and when they branch to form kidney, lung, and salivary gland ducts. | 1 | Biochemistry |
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