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The potentially unlimited source of cell and tissues may have direct application for tissue engineering, cell replacement and transplantation following acute injuries and reconstructive surgery. These applications are limited to the cell types that can be differentiated efficiently and safely from human PSCs with the proper organogenesis. Decellularized organs are also being used as tissue scaffold for organogenesis. Source material can be normal healthy cells from another donor (heterologous transplantation) or genetically corrected from the same patient (autologous).
Concerns on patient safety have been raised due to the possibility of contaminating undifferentiated cells. The first clinical trial using hESC-derived cells was in 2011. The first clinical trial using hiPSC-derived cells started in 2014 in Japan. | 2 | Tissue Engineering |
An oxyacid molecule contains the structure X−O−H, where other atoms or atom groups can be connected to the central atom X. In a solution, such a molecule can be dissociated into ions in two distinct ways:
* X−O−H ⇄ (X−O) + H
* X−O−H ⇄ X + OH
If the central atom X is strongly electronegative, then it strongly attracts the electrons of the oxygen atom. In that case, the bond between the oxygen and hydrogen atom is weak, and the compound ionizes easily in the way of the former of the two chemical equations above. In this case, the compound XOH is an acid, because it releases a proton, that is, a hydrogen ion. For example, nitrogen, sulfur and chlorine are strongly electronegative elements, and therefore nitric acid, sulfuric acid, and perchloric acid, are strong acids.
If, however, the electronegativity of X is low, then the compound is dissociated to ions according to the latter chemical equation, and XOH is an alkaline hydroxide. Examples of such compounds are sodium hydroxide NaOH and calcium hydroxide Ca(OH). Owing to the high electronegativity of oxygen, however, most of the common oxobases, such as sodium hydroxide, while strongly basic in water, are only moderately basic in comparison to other bases. For example, the pKa of the conjugate acid of sodium hydroxide, water, is 15.7, while that of sodium amide, ammonia, is closer to 40, making sodium hydroxide a much weaker base than sodium amide.
If the electronegativity of X is somewhere in between, the compound can be amphoteric, and in that case it can dissociate to ions in both ways, in the former case when reacting with bases, and in the latter case when reacting with acids. Examples of this include aliphatic alcohols, such as ethanol.
Inorganic oxyacids typically have a chemical formula of type HXO, where X is an atom functioning as a central atom, whereas parameters m and n depend on the oxidation state of the element X. In most cases, the element X is a nonmetal, but some metals, for example chromium and manganese, can form oxyacids when occurring at their highest oxidation states.
When oxyacids are heated, many of them dissociate to water and the anhydride of the acid. In most cases, such anhydrides are oxides of nonmetals. For example, carbon dioxide, CO, is the anhydride of carbonic acid, HCO, and sulfur trioxide, SO, is the anhydride of sulfuric acid, HSO. These anhydrides react quickly with water and form those oxyacids again.
Many organic acids, like carboxylic acids and phenols, are oxyacids. Their molecular structure, however, is much more complicated than that of inorganic oxyacids.
Most of the commonly encountered acids are oxyacids. Indeed, in the 18th century, Lavoisier assumed that all acids contain oxygen and that oxygen causes their acidity. Because of this, he gave to this element its name, oxygenium, derived from Greek and meaning acid-maker, which is still, in a more or less modified form, used in most languages. Later, however, Humphry Davy showed that the so-called muriatic acid did not contain oxygen, despite its being a strong acid; instead, it is a solution of hydrogen chloride, HCl. Such acids which do not contain oxygen are nowadays known as hydroacids. | 4 | Acids + Bases |
We take a very simple situation in which each atom can be approximated as a two state system. The thermal energy is so low that the atom is in the ground state. In this ground state, the atom is assumed to have no net orbital angular momentum but only one unpaired electron to give it a spin of the half. In the presence of an external magnetic field, the ground state will split into two states having an energy difference proportional to the applied field. The spin of the unpaired electron is parallel to the field in the higher energy state and anti-parallel in the lower one.
A density matrix, , is a matrix that describes a quantum system in a mixed state, a statistical ensemble of several quantum states (here several similar 2-state atoms). This should be contrasted with a single state vector that describes a quantum system in a pure state. The expectation value of a measurement, , over the ensemble is . In terms of a complete set of states, , one can write
Von Neumann's equation tells us how the density matrix evolves with time.
In equilibrium,
one has , and the allowed density matrices are
The canonical ensemble has
where
For the 2-state system, we can write
Here is the gyromagnetic ratio.
Hence , and
From which | 7 | Magnetic Ordering |
If the underlying infertility is related to abnormalities in spermatogenesis, it is plausible, but too early to examine that male offspring are at higher risk for sperm abnormalities.
IVF does not seem to confer any risks regarding cognitive development, school performance, social functioning, and behaviour. Also, IVF infants are known to be as securely attached to their parents as those who were naturally conceived, and IVF adolescents are as well-adjusted as those who have been naturally conceived.
Limited long-term follow-up data suggest that IVF may be associated with an increased incidence of hypertension, impaired fasting glucose, increase in total body fat composition, advancement of bone age, subclinical thyroid disorder, early adulthood clinical depression and binge drinking in the offspring. It is not known, however, whether these potential associations are caused by the IVF procedure in itself, by adverse obstetric outcomes associated with IVF, by the genetic origin of the children or by yet unknown IVF-associated causes. Increases in embryo manipulation during IVF result in more deviant fetal growth curves, but birth weight does not seem to be a reliable marker of fetal stress.
IVF, including ICSI, is associated with an increased risk of imprinting disorders (including Prader–Willi syndrome and Angelman syndrome), with an odds ratio of 3.7 (95% confidence interval 1.4 to 9.7).
An IVF-associated incidence of cerebral palsy and neurodevelopmental delay are believed to be related to the confounders of prematurity and low birthweight. Similarly, an IVF-associated incidence of autism and attention-deficit disorder are believed to be related to confounders of maternal and obstetric factors.
Overall, IVF does not cause an increased risk of childhood cancer. Studies have shown a decrease in the risk of certain cancers and an increased risks of certain others including retinoblastoma, hepatoblastoma and rhabdomyosarcoma. | 1 | Cryobiology |
Flow rate of the liquid phase and mole fraction of the desired compound in it are and .
Flow rate of the vapour phase and mole fraction of the desired compound in it are and . | 5 | Separation Processes |
UV attack by sunlight can be ameliorated or prevented by adding anti-UV polymer stabilizers, usually prior to shaping the product by injection moulding. UV stabilizers in plastics usually act by absorbing the UV radiation preferentially, and dissipating the energy as low-level heat. The chemicals used are similar to those in sunscreen products, which protect skin from UV attack. They are used frequently in plastics, including cosmetics and films. Different UV stabilizers are utilized depending upon the substrate, intended functional life, and sensitivity to UV degradation. UV stabilizers, such as benzophenones, work by absorbing the UV radiation and preventing the formation of free radicals. Depending upon substitution, the UV absorption spectrum is changed to match the application. Concentrations normally range from 0.05% to 2%, with some applications up to 5%.
Frequently, glass can be a better alternative to polymers when it comes to UV degradation. Most of the commonly used glass types are highly resistant to UV radiation. Explosion protection lamps for oil rigs for example can be made either from polymer or glass. Here, the UV radiation and rough weathers belabor the polymer so much, that the material has to be replaced frequently.
Poly(ethylene-naphthalate) (PEN) can be protected by applying a zinc oxide coating, which acts as protective film reducing the diffusion of oxygen. Zinc oxide can also be used on polycarbonate (PC) to decrease the oxidation and photo-yellowing rate caused by solar radiation. | 8 | Ultraviolet Radiation |
Electroluminescence can be exploited in light sources. Such sources typically emit from a large area, which makes them suitable for backlights of LCD displays. The excitation of the phosphor is usually achieved by application of high-intensity electric field, usually with suitable frequency. Current electroluminescent light sources tend to degrade with use, resulting in their relatively short operation lifetimes.
ZnS:Cu was the first formulation successfully displaying electroluminescence, tested at 1936 by Georges Destriau in Madame Marie Curie laboratories in Paris.
Powder or AC electroluminescence is found in a variety of backlight and night light applications. Several groups offer branded EL offerings (e.g. IndiGlo used in some Timex watches) or "Lighttape", another trade name of an electroluminescent material, used in electroluminescent light strips. The Apollo space program is often credited with being the first significant use of EL for backlights and lighting. | 0 | Luminescence |
Glucocerebroside (also called glucosylceramide) is any of the cerebrosides in which the monosaccharide head group is glucose. | 6 | Carbohydrates |
As ozone in the atmosphere prevents most energetic ultraviolet radiation reaching the surface of the Earth, astronomical data in these wavelengths have to be gathered from satellites orbiting above the atmosphere and ozone layer. Most of the light from young hot stars is in the ultraviolet and so study of these wavelengths is important for studying the origins of galaxies. The Galaxy Evolution Explorer, GALEX, is an orbiting ultraviolet space telescope launched on April 28, 2003, which operated until early 2012. | 8 | Ultraviolet Radiation |
To illustrate the difficulty of building a beam-target fusion system, we will consider one promising fusion fuel, the proton-boron cycle, or p-B11.
Boron can be formed into highly purified solid blocks, and protons easily produced by ionizing hydrogen gas. The protons can be accelerated and fired into the boron block, and the reactions will cause several alpha particles to be released. These can be collected in an electrostatic system to directly produce electricity without having to use a Rankine cycle or a similar heat-driven system. As the reactions create no neutrons directly, they have many practical advantages for safety also.
The chance of a collision is maximized when the protons have an energy of about 675 keV. When they fuse, the alphas carry away a total of 8.7 MeV. Some of that energy, 0.675 MeV, must be recycled into the accelerator to produce new protons to continue the process, and the generation and acceleration process is unlikely to be much more than 50% efficient. This still leaves ample net energy to close the cycle. However, this assumes every proton causes a fusion event, which does not occur. Considering the probability of a reaction, the resultant cycle is:
where and are the probabilities that any given proton or boron will undergo a reaction. Re-arranging, we can show that:
That means that to break even, the system needs at least of the particles to undergo fusion. To ensure that a proton has a chance to collide with a boron, it must travel past many boron atoms. The collision rate is:
where is the nuclear cross section between a proton and boron, is the density of boron, and is the average distance the proton travels through the boron before undergoing a fusion reaction. For p-B11, is 0.9 x 10 cm, is 2.535 g/cm, and thus ~ 8 cm. However, travelling through the block causes the proton to ionize the boron atoms it passes, which slows the proton. At 0.675 MeV, this process slows the proton to sub-keV energies in about 10 cm, many orders of magnitude less than what is required. | 3 | Nuclear Fusion |
In the United States, sperm banks maintain lists or catalogs of donors which provide basic information about the donor such as racial origin, skin color, height, weight, color of eyes, and blood group. Some of these catalogs are available for browsing on the Internet, while others are made available to patients only when they apply to a sperm bank for treatment. Some sperm banks make additional information about each donor available for an additional fee, and others make additional basic information known to children produced from donors when those children reach the age of 18. Some clinics offer "exclusive donors" whose sperm is used to produce pregnancies for only one recipient woman. How accurate this is, or can be, is not known, and neither is it known whether the information produced by sperm banks, or by the donors themselves, is true. Many sperm banks will, however, carry out whatever checks they can to verify the information they request, such as checking the identity of the donor and contacting his own doctor to verify medical details.
In the United Kingdom, most donors are anonymous at the point of donation and recipients can see only non-identifying information about their donor (height, weight, ethnicity etc.). Donors need to provide identifying information to the clinic and clinics will usually ask the donors doctor to confirm any medical details they have been given. Donors are asked to provide a pen portrait of themselves which is held by the HFEA and can be obtained by the adult conceived from the donation at the age of 18, along with identifying information such as the donors name and last known address. Known donation is permitted and it is not uncommon for family or friends to donate to a recipient couple.
Qualities that potential recipients typically prefer in donors include the donors being tall, college educated, and with a consistently high sperm count.
A review came to the result that 68% of donors had given information to the clinical staff regarding physical characteristics and education but only 16% had provided additional information such as hereditary aptitudes and temperament or character. | 1 | Cryobiology |
Collagen is the primary component of the extracellular matrix. Collagen scaffolds efficiently support fibroblast growth, which in turn allows keratinocytes to grow nicely into multilayers. Collagen (mainly collagen type I) is often used as a scaffold because it is biocompatible, non-immunogenic and available. However, collagen biodegrades relatively rapidly and is not good at withstanding mechanical forces. Improved characteristics can be created by cross-linking collagen-based matrices: this is an effective method to correct the instability and mechanical properties. | 2 | Tissue Engineering |
In the case of the original Grätzel and O'Regan design, the cell has 3 primary parts. On top is a transparent anode made of fluoride-doped tin dioxide (SnO:F) deposited on the back of a (typically glass) plate. On the back of this conductive plate is a thin layer of titanium dioxide (TiO), which forms into a highly porous structure with an extremely high surface area. The (TiO) is chemically bound by a process called sintering. TiO only absorbs a small fraction of the solar photons (those in the UV). The plate is then immersed in a mixture of a photosensitive ruthenium-polypyridyl dye (also called molecular sensitizers) and a solvent. After soaking the film in the dye solution, a thin layer of the dye is left covalently bonded to the surface of the TiO. The bond is either an ester, chelating, or bidentate bridging linkage.
A separate plate is then made with a thin layer of the iodide electrolyte spread over a conductive sheet, typically platinum metal. The two plates are then joined and sealed together to prevent the electrolyte from leaking. The construction is simple enough that there are hobby kits available to hand-construct them. Although they use a number of "advanced" materials, these are inexpensive compared to the silicon needed for normal cells because they require no expensive manufacturing steps. TiO, for instance, is already widely used as a paint base.
One of the efficient DSSCs devices uses ruthenium-based molecular dye, e.g. [Ru(4,4-dicarboxy-2,2-bipyridine)(NCS)] (N3), that is bound to a photoanode via carboxylate moieties. The photoanode consists of 12 μm thick film of transparent 10–20 nm diameter TiO nanoparticles covered with a 4 μm thick film of much larger (400 nm diameter) particles that scatter photons back into the transparent film. The excited dye rapidly injects an electron into the TiO after light absorption. The injected electron diffuses through the sintered particle network to be collected at the front side transparent conducting oxide (TCO) electrode, while the dye is regenerated via reduction by a redox shuttle, I/I, dissolved in a solution. Diffusion of the oxidized form of the shuttle to the counter electrode completes the circuit. | 8 | Ultraviolet Radiation |
react with or , forming thiosulfuric acid , as the analogous reaction with forms disulfonomonosulfonic acid ; similarly polysulfanes HS (n = 2–6) give HSSOH. Reactions from both ends of the polysulfane chain lead to the formation of polysulfonodisulfonic acid HOSSSOH.
Many methods exist for the synthesis of these acids, but the mechanism is unclear because of the large number of simultaneously occurring and competing reactions such as redox, chain transfer, and disproportionation. Typical examples are:
* Interaction between hydrogen sulfide and sulfur dioxide in highly dilute aqueous solution. This yields a complex mixture of various oxyacids of sulfur of different structures, called Wackenroder solution. At temperatures above 20 °C solutes slowly decomposes with separation unit sulfur, sulfur dioxide, and sulfuric acid.
::HS + HSO → HSO + HO
::HSO + 2 HSO → HSO + 2 HO
::HSO + HSO → HSO + HSO
* Reactions of sulfur halides with or , for example :
:: SCl + 2 → [OSSSO ] + 2 HCl
:: SCl + 2 → [OSSSO] + 2 HCl
:: SCl + 2 → [OSSSO] + 2 HCl
Anhydrous polythionic acids can be formed in diethyl ether solution by the following three general ways:
: HSSOH + SO → HSO (n = 1, 2 ... 8)
: HS + 2 SO → HSO (n = 1, 2 ... 8)
: 2 HSSOH + I → HSO + 2 HI (n = 1, 2 ... 6)
Polythionic acids with a small number of sulfur atoms in the chain (n = 3, 4, 5, 6) are the most stable. Polythionic acids are stable only in aqueous solutions, and are rapidly destroyed at higher concentrations with the release of sulfur, sulfur dioxide and - sometimes - sulfuric acid. Acid salts of polythionic acids do not exist. Polythionate ions are significantly more stable than the corresponding acids.
Under the action of oxidants (potassium permanganate, potassium dichromate) polythionic acids and their salts are oxidized to sulfate, and the interaction with strong reducing agents (amalgam of sodium) converts them into sulfites and dithionites. | 4 | Acids + Bases |
Mechanoluminescence is light emission resulting from any mechanical action on a solid. It can be produced through ultrasound, or through other means.
* Electrochemiluminescence is the emission induced by an electrochemical stimulus.
* Fractoluminescence is caused by stress that results in the formation of fractures, that in turn yield light.
* Piezoluminescence is caused by pressure that results in elastic deformation and large polarization from the piezoelectric effect.
* Sonoluminescence is the emission of short bursts of light from imploding bubbles in a liquid when excited by sound.
* Triboluminescence is nominally caused by rubbing, but sometimes occurs because of resulting fractoluminescence. It is often used as a synonym. | 0 | Luminescence |
In solid-state physics, the Landau–Lifshitz equation (LLE), named for Lev Landau and Evgeny Lifshitz, is a partial differential equation describing time evolution of magnetism in solids, depending on 1 time variable and 1, 2, or 3 space variables. | 7 | Magnetic Ordering |
Dye sensitised solar cells operate as a photoanode (n-DSC), where photocurrent result from electron injection by the sensitized dye. Photocathodes (p-DSCs) operate in an inverse mode compared to the conventional n-DSC, where dye-excitation is followed by rapid electron transfer from a p-type semiconductor to the dye (dye-sensitized hole injection, instead of electron injection). Such p-DSCs and n-DSCs can be combined to construct tandem solar cells (pn-DSCs) and the theoretical efficiency of tandem DSCs is well beyond that of single-junction DSCs.
A standard tandem cell consists of one n-DSC and one p-DSC in a simple sandwich configuration with an intermediate electrolyte layer. n-DSC and p-DSC are connected in series, which implies that the resulting photocurrent will be controlled by the weakest photoelectrode, whereas photovoltages are additive. Thus, photocurrent matching is very important for the construction of highly efficient tandem pn-DSCs. However, unlike n-DSCs, fast charge recombination following dye-sensitized hole injection usually resulted in low photocurrents in p-DSC and thus hampered the efficiency of the overall device.
Researchers have found that using dyes comprising a perylenemonoimide (PMI) as the acceptor and an oligothiophene coupled to triphenylamine as the donor greatly improve the performance of p-DSC by reducing charge recombination rate following dye-sensitized hole injection. The researchers constructed a tandem DSC device with NiO on the p-DSC side and TiO on the n-DSC side. Photocurrent matching was achieved through adjustment of NiO and TiO film thicknesses to control the optical absorptions and therefore match the photocurrents of both electrodes. The energy conversion efficiency of the device is 1.91%, which exceeds the efficiency of its individual components, but is still much lower than that of high performance n-DSC devices (6%–11%). The results are still promising since the tandem DSC was in itself rudimentary. The dramatic improvement in performance in p-DSC can eventually lead to tandem devices with much greater efficiency than lone n-DSCs.
As previously mentioned, using a solid-state electrolyte has several advantages over a liquid system (such as no leakage and faster charge transport), which has also been realised for dye-sensitised photocathodes. Using electron transporting materials such as PCBM, TiO and ZnO instead of the conventional liquid redox couple electrolyte, researchers have managed to fabricate solid state p-DSCs (p-ssDSCs), aiming for solid state tandem dye sensitized solar cells, which have the potential to achieve much greater photovoltages than a liquid tandem device. | 8 | Ultraviolet Radiation |
Chloroauric acid is an inorganic compound with the chemical formula . It forms hydrates . Both the trihydrate and tetrahydrate are known. Both are orange-yellow solids consisting of the planar anion. Often chloroauric acid is handled as a solution, such as those obtained by dissolution of gold in aqua regia. These solutions can be converted to other gold complexes or reduced to metallic gold or gold nanoparticles. | 4 | Acids + Bases |
The 2013 ILCOR and 2010 American Heart Association guidelines support the use of cooling following resuscitation from cardiac arrest. These recommendations were largely based on two trials from 2002 which showed improved survival and brain function when cooled to after cardiac arrest.
However, more recent research suggests that there is no benefit to cooling to when compared with less aggressive cooling only to a near-normal temperature of ; it appears cooling is effective because it prevents fever, a common complication seen after cardiac arrest. There is no difference in long term quality of life following mild compared to more severe cooling.
In children, following cardiac arrest, cooling does not appear useful as of 2018. | 1 | Cryobiology |
Many reef aquarium keepers use RO systems to make fish-friendly seawater. Ordinary tap water can contain excessive chlorine, chloramines, copper, nitrates, nitrites, phosphates, silicates, or other chemicals detrimental to marine organisms. Contaminants such as nitrogen and phosphates can lead to unwanted algae growth. An effective combination of both RO and deionization is popular among reef aquarium keepers, and is preferred above other water purification processes due to the low cost of ownership and operating costs. Where chlorine and chloramines are found in the water, carbon filtration is needed before RO, as common residential membranes do not address these compounds.
Freshwater aquarists also use RO to duplicate the soft waters found in many tropical waters. While many tropical fish can survive in treated tap water, breeding can be impossible. Many aquatic shops sell containers of RO water for this purpose. | 5 | Separation Processes |
The effectiveness of germicidal UV depends on the duration a microorganism is exposed to UV, the intensity and wavelength of the UV radiation, the presence of particles that can protect the microorganisms from UV, and a microorganism's ability to withstand UV during its exposure.
In many systems, redundancy in exposing microorganisms to UV is achieved by circulating the air or water repeatedly. This ensures multiple passes so that the UV is effective against the highest number of microorganisms and will irradiate resistant microorganisms more than once to break them down.
"Sterilization" is often misquoted as being achievable. While it is theoretically possible in a controlled environment, it is very difficult to prove and the term "disinfection" is generally used by companies offering this service as to avoid legal reprimand. Specialist companies will often advertise a certain log reduction, e.g., 6-log reduction or 99.9999% effective, instead of sterilization. This takes into consideration a phenomenon known as light and dark repair (photoreactivation and base excision repair, respectively), in which a cell can repair DNA that has been damaged by UV light.
The effectiveness of this form of disinfection depends on line-of-sight exposure of the microorganisms to the UV light. Environments where design creates obstacles that block the UV light are not as effective. In such an environment, the effectiveness is then reliant on the placement of the UVGI system so that line of sight is optimum for disinfection.
Dust and films coating the bulb lower UV output. Therefore, bulbs require periodic cleaning and replacement to ensure effectiveness. The lifetime of germicidal UV bulbs varies depending on design. Also, the material that the bulb is made of can absorb some of the germicidal rays.
Lamp cooling under airflow can also lower UV output. Increases in effectiveness and UV intensity can be achieved by using reflection. Aluminum has the highest reflectivity rate versus other metals and is recommended when using UV.
One method for gauging UV effectiveness in water disinfection applications is to compute UV dose. The U.S. Environmental Protection Agency (EPA) published UV dosage guidelines for water treatment applications in 1986. UV dose cannot be measured directly but can be inferred based on the known or estimated inputs to the process:
* Flow rate (contact time)
* Transmittance (light reaching the target)
* Turbidity (cloudiness)
* Lamp age or fouling or outages (reduction in UV intensity)
In air and surface disinfection applications the UV effectiveness is estimated by calculating the UV dose which will be delivered to the microbial population. The UV dose is calculated as follows:
: UV dose (μW·s/cm) = UV intensity (μW/cm) × exposure time (seconds)
The UV intensity is specified for each lamp at a distance of 1 meter. UV intensity is inversely proportional to the square of the distance so it decreases at longer distances. Alternatively, it rapidly increases at distances shorter than 1m. In the above formula, the UV intensity must always be adjusted for distance unless the UV dose is calculated at exactly from the lamp. Also, to ensure effectiveness, the UV dose must be calculated at the end of lamp life (EOL is specified in number of hours when the lamp is expected to reach 80% of its initial UV output) and at the furthest distance from the lamp on the periphery of the target area. Some shatter-proof lamps are coated with a fluorated ethylene polymer to contain glass shards and mercury in case of breakage; this coating reduces UV output by as much as 20%.
To accurately predict what UV dose will be delivered to the target, the UV intensity, adjusted for distance, coating, and end of lamp life, will be multiplied by the exposure time. In static applications the exposure time can be as long as needed for an effective UV dose to be reached. In case of rapidly moving air, in AC air ducts, for example, the exposure time is short, so the UV intensity must be increased by introducing multiple UV lamps or even banks of lamps. Also, the UV installation should ideally be located in a long straight duct section with the lamps directing UVC in a direction parallel to the airflow to maximize the time the air is irradiated.
These calculations actually predict the UV fluence and it is assumed that the UV fluence will be equal to the UV dose. The UV dose is the amount of germicidal UV energy absorbed by a microbial population over a period of time. If the microorganisms are planktonic (free floating) the UV fluence will be equal the UV dose. However, if the microorganisms are protected by mechanical particles, such as dust and dirt, or have formed biofilm a much higher UV fluence will be needed for an effective UV dose to be introduced to the microbial population. | 8 | Ultraviolet Radiation |
Glow sticks emit light when two chemicals are mixed. The reaction between the two chemicals is catalyzed by a base, usually sodium salicylate. The sticks consist of a tiny, brittle container within a flexible outer container. Each container holds a different solution. When the outer container is flexed, the inner container breaks, allowing the solutions to combine, causing the necessary chemical reaction. After breaking, the tube is shaken to thoroughly mix the components.
The glow stick contains two chemicals, a base catalyst, and a suitable dye (sensitizer, or fluorophor). This creates an exergonic reaction. The chemicals inside the plastic tube are a mixture of the dye, the base catalyst, and diphenyl oxalate. The chemical in the glass vial is hydrogen peroxide. By mixing the peroxide with the phenyl oxalate ester, a chemical reaction takes place, yielding two moles of phenol and one mole of peroxyacid ester (1,2-dioxetanedione). The peroxyacid decomposes spontaneously to carbon dioxide, releasing energy that excites the dye, which then relaxes by releasing a photon. The wavelength of the photon—the color of the emitted light—depends on the structure of the dye. The reaction releases energy mostly as light, with very little heat. The reason for this is that the reverse [[Woodward-Hoffmann rules|[2 + 2] photocycloadditions]] of 1,2-dioxetanedione is a forbidden transition (it violates Woodward–Hoffmann rules) and cannot proceed through a regular thermal mechanism.
By adjusting the concentrations of the two chemicals and the base, manufacturers can produce glow sticks that glow either brightly for a short amount of time or more dimly for an extended length of time. This also allows glow sticks to perform satisfactorily in hot or cold climates, by compensating for the temperature dependence of reaction. At maximum concentration (typically found only in laboratory settings), mixing the chemicals results in a furious reaction, producing large amounts of light for only a few seconds. The same effect can be achieved by adding copious amounts of sodium salicylate or other bases. Heating a glow stick also causes the reaction to proceed faster and the glow stick to glow more brightly for a brief period. Cooling a glow stick slows the reaction a small amount and causes it to last longer, but the light is dimmer. This can be demonstrated by refrigerating or freezing an active glow stick; when it warms up again, it will resume glowing. The dyes used in glow sticks usually exhibit fluorescence when exposed to ultraviolet radiation—even a spent glow stick may therefore shine under a black light.
The light intensity is high immediately after activation, then exponentially decays. Leveling of this initial high output is possible by refrigerating the glow stick before activation.
A combination of two fluorophores can be used, with one in the solution and another incorporated to the walls of the container. This is advantageous when the second fluorophore would degrade in solution or be attacked by the chemicals. The emission spectrum of the first fluorophore and the absorption spectrum of the second one have to largely overlap, and the first one has to emit at shorter wavelength than the second one. A downconversion from ultraviolet to visible is possible, as is conversion between visible wavelengths (e.g., green to orange) or visible to near-infrared. The shift can be as much as 200 nm, but usually the range is about 20–100 nm longer than the absorption spectrum. Glow sticks using this approach tend to have colored containers, due to the dye embedded in the plastic. Infrared glow sticks may appear dark-red to black, as the dyes absorb the visible light produced inside the container and reemit near-infrared.
On the other hand, various colors can also be achieved by simply mixing several fluorophores within the solution to achieve the desired effect. These various colors can be achieved due to the principles of additive color. For example, a combination of red, yellow, and green fluorophores is used in orange light sticks, and a combination of several fluorescers is used in white light sticks. | 0 | Luminescence |
Lactulose is not absorbed in the small intestine nor broken down by human enzymes, thus stays in the digestive bolus through most of its course, causing retention of water through osmosis leading to softer, easier-to-pass stool. It has a secondary laxative effect in the colon, where it is fermented by the gut flora, producing metabolites which have osmotic powers and peristalsis-stimulating effects (such as acetate), but also methane associated with flatulence.
Lactulose is metabolized in the colon by bacterial flora into short-chain fatty acids, including lactic acid and acetic acid. These partially dissociate, acidifying the colonic contents (increasing the H concentration in the gut). This favors the formation of the nonabsorbable from NH, trapping NH in the colon and effectively reducing plasma NH concentrations. Lactulose is therefore effective in treating hepatic encephalopathy. Specifically, it is effective as secondary prevention of hepatic encephalopathy in people with cirrhosis. Moreover, research showed improved cognitive functions and health-related quality of life in people with cirrhosis with minimal hepatic encephalopathy treated with lactulose. | 6 | Carbohydrates |
In 2020, a team of NASA researchers seeking a new energy source for deep-space exploration missions published the first paper describing a method for triggering nuclear fusion in the space between the atoms of a metal solid, an example of screened fusion. The experiments did not produce self-sustaining reactions, and the electron source itself was energetically expensive. | 3 | Nuclear Fusion |
Strontium aluminate is an aluminate compound with the chemical formula (sometimes written as ). It is a pale yellow, monoclinic crystalline powder that is odourless and non-flammable. When activated with a suitable dopant (e.g. europium, written as ), it acts as a photoluminescent phosphor with long persistence of phosphorescence.
Strontium aluminates exist in a variety of other compositions including (monoclinic), (cubic), (hexagonal), and (orthorhombic). The different compositions cause different colours of light to be emitted. | 0 | Luminescence |
A typical sublimation apparatus separates a mix of appropriate solid materials in a vessel in which it applies heat under a controllable atmosphere (air, vacuum or inert gas). If the material is not at first solid, then it may freeze under reduced pressure. Conditions are so chosen that the solid volatilizes and condenses as a purified compound on a cooled surface, leaving the non-volatile residual impurities or solid products behind.
The form of the cooled surface often is a so-called cold finger which for very low-temperature sublimation may actually be cryogenically cooled. If the operation is a batch process, then the sublimed material can be collected from the cooled surface once heating ceases and the vacuum is released. Although this may be quite convenient for small quantities, adapting sublimation processes to large volume is generally not practical with the apparatus becoming extremely large and generally needing to be disassembled to recover products and remove residue.
Among the advantages of applying the principle to certain materials are the comparatively low working temperatures, reduced exposure to gases such as oxygen that might harm certain products, and the ease with which it can be performed on extremely small quantities. The same apparatus may also be used for conventional distillation of extremely small quantities due to the very small volume and surface area between evaporating and condensing regions, although this is generally only useful if the cold finger can be cold enough to solidify the condensate. | 5 | Separation Processes |
UV light (specifically, UV‑B) causes the body to produce vitamin D, which is essential for life. Humans need some UV radiation to maintain adequate vitamin D levels. According to the World Health Organization:
Vitamin D can also be obtained from food and supplementation. Excess sun exposure produces harmful effects, however.
Vitamin D promotes the creation of serotonin. The production of serotonin is in direct proportion to the degree of bright sunlight the body receives. Serotonin is thought to provide sensations of happiness, well-being and serenity to human beings. | 8 | Ultraviolet Radiation |
The Downdraft skimmer is both a proprietary skimmer design and a style of protein skimmer that injects water under high pressure into tubes that have a foam or bubble generating mechanism and carry the air/water mixture down into the skimmer and into a separate chamber. The proprietary design is protected in the United States with patents and commercial skimmer products in the US are limited to that single company. Their design uses one or more tubes with plastic media such as bio balls inside to mix water under high pressure and air in the body of the skimmer resulting in foam that collects protein waste in a collection cup. This was one of the earlier high performance protein skimmer designs and large models were produced that saw success in large and public aquariums. | 5 | Separation Processes |
Numerous acids and salts of this group have a venerable history, and chemistry systems, where they exist, dates back to the studies John Dalton devoted to the behavior of hydrogen sulfide in aqueous solutions of sulfur dioxide (1808). This solution now has the name of Heinrich Wilhelm Ferdinand Wackenroder, who conducted a systematic study (1846). Over the next 60–80 years, numerous studies have shown the presence of ions, in particular tetrathionate and pentathionate anion ( and , respectively). | 4 | Acids + Bases |
It was determined that each Chapter would have its own Council, the overall activities being determined by the Governing Board, on which each Council was represented, and an executive committee. | 2 | Tissue Engineering |
Sucrose is a disaccharide, a molecule composed of the two monosaccharides glucose, and fructose. Invertase is the enzyme cleaves the glycosidic linkage between the glucose and fructose molecules.
In most wines, there will be very little sucrose, since it is not a natural constituent of grapes and sucrose added for the purpose of chaptalisation will be consumed in the fermentation. The exception to this rule is Champagne and other sparkling wines, to which an amount of liqueur dexpédition (typically sucrose dissolved in a still wine) is added after the second fermentation in bottle, a practice known as dosage'. | 6 | Carbohydrates |
Another approach is low-pressure high-recovery multistage RO (LPHR). It produces concentrated brine and freshwater by cycling the output repeatedly through a relatively porous membrane at relatively low pressure. Each cycle removes additional impurities. Once the output is relatively pure, it is sent through a conventional RO membrane at conventional pressure to complete the filtration step. LPHR was found to be economically feasible, recovering more than 70% with an OPD between 58 and 65 bar and leaving no more than 350 ppm TDS from a seawater feed with 35,000 ppm TDS. | 5 | Separation Processes |
A cold fusion experiment usually includes:
* a metal, such as palladium or nickel, in bulk, thin films or powder; and
* deuterium, hydrogen, or both, in the form of water, gas or plasma.
Electrolysis cells can be either open cell or closed cell. In open cell systems, the electrolysis products, which are gaseous, are allowed to leave the cell. In closed cell experiments, the products are captured, for example by catalytically recombining the products in a separate part of the experimental system. These experiments generally strive for a steady state condition, with the electrolyte being replaced periodically. There are also "heat-after-death" experiments, where the evolution of heat is monitored after the electric current is turned off.
The most basic setup of a cold fusion cell consists of two electrodes submerged in a solution containing palladium and heavy water. The electrodes are then connected to a power source to transmit electricity from one electrode to the other through the solution. Even when anomalous heat is reported, it can take weeks for it to begin to appear—this is known as the "loading time," the time required to saturate the palladium electrode with hydrogen (see "Loading ratio" section).
The Fleischmann and Pons early findings regarding helium, neutron radiation and tritium were never replicated satisfactorily, and its levels were too low for the claimed heat production and inconsistent with each other. Neutron radiation has been reported in cold fusion experiments at very low levels using different kinds of detectors, but levels were too low, close to background, and found too infrequently to provide useful information about possible nuclear processes. | 3 | Nuclear Fusion |
Copurification in a chemical or biochemical context is the physical separation by chromatography or other purification technique of two or more substances of interest from other contaminating substances. For substances to co-purify usually implies that these substances attract each other to form a non-covalent complex such as in a protein complex.
However, when fractionating mixtures, especially mixtures containing large numbers of components (for example a cell lysate), it is possible by chance that some components may copurify even though they don't form complexes. In this context the term copurification is sometimes used to denote when two biochemical activities or some other property are isolated together after purification but it is not certain if the sample has been purified to homogeneity (i.e., contains only one molecular species or one molecular complex). Hence these activities or properties are likely but not guaranteed to reside on the same molecule or in the same molecular complex. | 5 | Separation Processes |
* DMSO
* Ethylene glycol
* Glycerol
* 2-Methyl-2,4-pentanediol (MPD)
* Propylene glycol
* Sucrose
* Trehalose
*Heavy water [7] | 1 | Cryobiology |
Electroluminescent displays have been a very niche format and are very rarely used nowadays. Some uses have included to indicate speed and altitude at the front of the Concorde, and as floor indicators on Otis Elevators from around 1989 to 2007, mostly only available to high-rise buildings and modernizations. | 0 | Luminescence |
* Cryobiology, the branch of biology that studies the effects of low temperatures on living things
* Cryonics, the low-temperature preservation of people who cannot be sustained by contemporary medicine
* Cryoprecipitate, a blood-derived protein product used to treat some bleeding disorders
* Cryotherapy, medical treatment using cold
** Cryoablation, tissue removal using cold
** Cryosurgery, surgery using cold
* Cryo-electron microscopy (cryoEM), a technique that fires beams of electrons at proteins that have been frozen in solution, to deduce the biomolecules’ structure | 1 | Cryobiology |
A frozen zoo is a storage facility in which genetic materials taken from animals (e.g. DNA, sperm, eggs, embryos and live tissue) are stored at very low temperatures (−196 °C) in tanks of liquid nitrogen. Material preserved in this way can be stored indefinitely and used for artificial insemination, in vitro fertilization, embryo transfer, and cloning. There are a few frozen zoos across the world that implement this technology for conservation efforts. Several different species have been introduced to this technology, including the Pyrenean ibex, Black-footed ferret, and potentially the white rhinoceros. | 1 | Cryobiology |
The following are some examples of how DPN is being applied to potential products.
# Biosensor Functionalization – Directly place multiple capture domains on a single biosensor device
# Nanoscale Sensor Fabrication – Small, high-value sensors that can detect multiple targets
# Nanoscale Protein Chips – High-density protein arrays with increased sensitivity | 2 | Tissue Engineering |
The third approach of bioprinting is a combination of both the biomimicry and self-assembly approaches, called mini tissues. Organs and tissues are built from very small functional components. The mini-tissue approach takes these small pieces and arrange them into larger framework. | 2 | Tissue Engineering |
Some alternatives to IVF are:
*Artificial insemination, including intracervical insemination and intrauterine insemination of semen. It requires that a woman ovulates, but is a relatively simple procedure, and can be used in the home for self-insemination without medical practitioner assistance. The beneficiaries of artificial insemination are people who desire to give birth to their own child who may be single, people who are in a lesbian relationship or females who are in a heterosexual relationship but with a male partner who is infertile or who has a physical impairment which prevents full intercourse from taking place.
*Ovulation induction (in the sense of medical treatment aiming for the development of one or two ovulatory follicles) is an alternative for people with anovulation or oligoovulation, since it is less expensive and more easy to control. It generally involves antiestrogens such as clomifene citrate or letrozole, and is followed by natural or artificial insemination.
*Surrogacy, the process in which a surrogate agrees to bear a child for another person or persons, who will become the child's parent(s) after birth. People may seek a surrogacy arrangement when pregnancy is medically impossible, when pregnancy risks are too dangerous for the intended gestational carrier, or when a single man or a male couple wish to have a child.
*Adoption whereby a person assumes the parenting of another, usually a child, from that person's biological or legal parent or parents. | 1 | Cryobiology |
Bili light. A type of phototherapy that uses blue light with a range of 420–470 nm, used to treat neonatal jaundice. | 8 | Ultraviolet Radiation |
The mathematical definition is simple (and analogous to the so-called Wilson loop in quantum chromodynamics): One considers for example expressions ("total energies" or "Hamiltonians") of the form
where G is the graph considered, whereas the quantities are the so-called "exchange energies" between nearest-neighbours, which (in the energy units considered) assume the values ±1 (mathematically, this is a signed graph), while the are inner products of scalar or vectorial spins or pseudo-spins. If the graph G has quadratic or triangular faces P, the so-called "plaquette variables" P, "loop-products" of the following kind, appear:
: and respectively,
which are also called "frustration products". One has to perform a sum over these products, summed over all plaquettes. The result for a single plaquette is either +1 or −1. In the last-mentioned case the plaquette is "geometrically frustrated".
It can be shown that the result has a simple gauge invariance: it does not change – nor do other measurable quantities, e.g. the "total energy" – even if locally the exchange integrals and the spins are simultaneously modified as follows:
Here the numbers ε and ε are arbitrary signs, i.e. +1 or −1, so that the modified structure may look totally random. | 7 | Magnetic Ordering |
Once a single bubble is stabilized in the pressure antinode of the standing wave, it can be made to emit pulses of light by driving the bubble into highly nonlinear oscillations. This is done by the increasing pressure of the acoustic wave to disrupt the steady, linear growth of the bubble which cause the bubble to collapse in a runaway reaction that only reverts due to the high pressures inside the bubble at its minimum radius. | 0 | Luminescence |
Hysteresis can be observed in the stage-flow relationship of a river during rapidly changing conditions such as passing of a flood wave. It is most pronounced in low gradient streams with steep leading edge hydrographs. https://pubs.usgs.gov/ja/70193968/70193968.pdf | 7 | Magnetic Ordering |
The Migma device is perhaps the first significant attempt to solve the recirculation problem. It uses a storage system that was, in effect, an infinite number of storage rings arranged at different locations and angles. This is not done by added components or hardware configurations, but via careful arrangement of the magnetic fields within a wide but flat cylindrical vacuum chamber. Only ions undergoing very high angle scattering events would be lost, and calculations suggest that the rate of these events was such that any given ion would pass through the reaction area 10 times before scattering out. This would be enough to sustain positive energy output.
Several Migma devices were built and showed some promise, but it did not progress beyond moderately sized devices. Several theoretical concerns were raised based on space charge limit considerations, which suggested that increasing the density of the fuel to useful levels would require enormous magnets to confine it. During funding rounds the system became mired in an acrimonious debate with the various energy agencies and further development ended in the 1980s. | 3 | Nuclear Fusion |
Tetrabromoauric acid is an inorganic compound with the formula . It is the bromide analog of chloroauric acid. It is generated analogously, by reacting a mixture of hydrobromic and nitric acids with elemental gold. The oxidation state of gold in and anion is +3. The salts of (tetrabromoauric(III) acid) are tetrabromoaurates(III), containing anions (tetrabromoaurate(III) anions), which have square planar molecular geometry. | 4 | Acids + Bases |
Spinning cone columns are used in a form of low temperature vacuum steam distillation to gently extract volatile chemicals from liquid foodstuffs while minimising the effect on the taste of the product. For instance, the columns can be used to remove some of the alcohol from wine, off smells from cream, and to capture aroma compounds that would otherwise be lost in coffee processing. | 5 | Separation Processes |
Full details of the sequence of reactions that converts individual amino acids into the corresponding glucosinolate have been studied in the cress Arabidopsis thaliana.
A sequence of seven enzyme-catalysed steps is used. The sulfur atom is incorporated from glutathione (GSH) and the sugar component is added to the resulting thiol derivative by a glycosyltransferase before the final sulfonation step. | 6 | Carbohydrates |
In 1996 John Slonczewski expanded the model to account for the spin-transfer torque, i.e. the torque induced upon the magnetization by spin-polarized current flowing through the ferromagnet. This is commonly written in terms of the unit moment defined by :
where is the dimensionless damping parameter, and are driving torques, and is the unit vector along the polarization of the current. | 7 | Magnetic Ordering |
Lentztrehaloses A, B, and C are trehalose analogues found in an actinomycete Lentzea sp. ML457-mF8. Lentztrehaloses A and B can be synthesized chemically. The non-reducing disaccharide trehalose is commonly used in foods and various products as stabilizer and humectant, respectively. Trehalose has been shown to have curative effects for treating various diseases in animal models including neurodegenerative diseases, hepatic diseases, and arteriosclerosis. Trehalose, however, is readily digested by hydrolytic enzyme trehalase that is widely expressed in many organisms from microbes to human. As a result, trehalose may cause decomposition of the containing products. And its medicinal effect may be reduced by the hydrolysis by trehalase. Lentztrehaloses are rarely hydrolyzed by microbial and mammalian trehalases and may be used in various areas as a biologically stable substitute of trehalose. | 6 | Carbohydrates |
The structural changes that occur during 72-hour hypothermic storage of previously uninjured kidneys have been described by Mackay who showed how there was progressive vacuolation of the cytoplasm of the cells which particularly affected the proximal tubules. On electron microscopy the mitochondria were seen to become swollen with early separation of the internal cristal membranes and later loss of all internal structure. Lysosomal integrity was well preserved until late, and the destruction of the cell did not appear to be caused by lytic enzymes because there was no more injury immediately adjacent to the lysosomes than in the rest of the cell.
Woods and Liu – when describing successful 5 and 7 day kidney storage - described the light microscopic changes seen at the end of perfusion and at post mortem, but found few gross abnormalities apart from some infiltration with lymphocytes and occasional tubular atrophy.
The changes during short perfusions of human kidneys prior to reimplantation have been described by Hill who also performed biopsies 1 hour after reimplantation. On electron microscopy Hill found endothelial damage which correlated with the severity of the fibrin deposition after reimplantation. The changes that Hill saw in the glomeruli on light microscopy were occasional fibrin thrombi and infiltration with polymorphs. Hill suspected that these changes were an immunologically induced lesion, but found that there was no correlation between the severity of the histological lesion and the presence or absence of immunoglobulin deposits.
There are several reports of the analysis of urine produced by kidneys during perfusion storage. Kastagir analysed urine produced during 24-hour perfusion and found it to be an ultrafiltrate of the perfusate, Scott found a trace of protein in the urine during 24-hour storage, and Pederson found only a trace of protein after 36 hours perfusion storage. Pederson mentioned that he had found heavy proteinuria during earlier experiments. Woods noted protein casts in the tubules of viable kidneys after 5 day storage, but he did not analyse the urine produced during perfusion. In Cohen's study there was a progressive increase in urinary protein concentration during 8 day preservation until the protein content of the urine equalled that of the perfusate. This may have been related to the swelling of the glomerular basement membranes and the progressive fusion of epithelial cell foot processes that was also observed during the same period of perfusion storage. | 1 | Cryobiology |
The time of the NP decaying magnetic field for bound particles in SPMR measurements is on the order of seconds. Unbound particles of similar size decay on the order of milliseconds, contributing very little to the results.
The decay curve for bound NP is fit by an equation of the form
or
The constants are fit to the experimental data and a particular time point is used to extract the value of the magnetic field. The fields from all the sensor positions are then used to construct a field contour map. | 7 | Magnetic Ordering |
Light sources emitting in the UV spectral region are widely used in techniques involving photo-chemical processes, e.g., curing of inks, adhesives, varnishes and coatings, photolithography, UV induced growth of dielectrics, UV induced surface modification, and cleaning or material deposition. Incoherent sources of UV radiation have some advantages over laser sources because of their lower cost, a huge area of irradiation, and ease of use, especially when large-scale industrial processes are envisaged.
Mercury lamps (λ = 253.7 nm) are widely spread UV sources, but their production, use, and disposal of old lamps pose a threat to human health and environmental pollution. Comparing with commonly used mercury lamps, excimer lamps have a number of advantages. A specific feature of an excimer molecule is the absence of a strong bond in the ground electronic state. Thanks to this, high-intensity UV radiation can be extracted from a plasma without significant self-absorption. This makes possible to convert efficiently energy deposited to the active medium into UV radiation.
Excimer lamps are referred to cold sources of UV radiation since the radiating surface of excimer lamps remains at relatively low temperatures in contrast with traditional UV lamps like a mercury one. Because the medium does not need to be heated, excimer lamps reach their peak output almost immediately after they are turned on.
Rare gas and rare gas-halide excimer lamps generally radiate in the ultraviolet (UV) and vacuum-ultraviolet (VUV) spectral regions (see table). Their unique narrow-band emission characteristics, high quantum efficiency, and high-energy photons make them suitable for applications such as absorption spectroscopy, UV curing, UV coating, disinfection, ozone generation, destruction of gaseous organic waste, photo-etching and photo-deposition and more other applications.
Light sources emitting photons in the energy range of 3.5–10 eV find applications in many fields due to the ability of high-energy photons to cleave most chemical bonds and kill microbes destroying nucleic acids and disrupting their DNA. Examples of excimer lamp applications include purification and disinfection of drinking water, pool water, air, sewage purification, decontamination of industrial waste, photochemical synthesis and degradation of organic compounds in flue gases and water, photopolymerization of organic coatings and paints, and photo-enhanced chemical vapor deposition. In all cases UV photons excite species or cleave chemical bonds, resulting in the formation of radicals or other chemical reagents, which initiate a required reaction.
An excimer lamp has selective action. UV radiation of a given wavelength can selectively excite species or generate required radicals. Such lamps can be useful for photophysical and photochemical processing such as UV curing of paints, varnishes, and adhesives, cleansing and modifying surface properties, polymerization of lacquers and paints, and photo-degradation of a variety of pollutants. Photo-etching of polymers is possible using different wavelengths: 172 nm by xenon excimer, 222 nm by krypton chloride, and 308 nm by xenon chloride. Excimer UV sources can be used for microstructuring large-area polymer surfaces. XeCl-excimer lamps (308 nm) are especially suitable to get tan.
Fluorescence spectroscopy is one of the most common methods for detecting biomolecules. Biomolecules can be labeled with fluoroprobe, which then is excited by a short pulse of UV light, leading to re-emission in the visible spectral region. Detecting this re-emitted light, one can judge the density of labeled molecules. Lanthanide complexes are commonly used as fluoroprobes. Due to their long lifetime, they play an important role in Förster resonance energy transfer (FRET) analysis.
At present, excimer lamps are coming into use in ecology, photochemistry, photobiology, medicine, criminalistics, petrochemistry, physics, microelectronics, different engineering tasks, wide-ranging technologies, science, various branches of industry including the food industry, and many others. | 8 | Ultraviolet Radiation |
According to researchers and activists, countries typically associated with acid assault include Bangladesh, India, Nepal, Cambodia, Vietnam, Laos, United Kingdom, Kenya, South Africa, Uganda, Pakistan, and Afghanistan. Acid attacks have been reported however in countries around the world, including:
* Afghanistan
* Australia
* Bangladesh
* Belgium
* Bulgaria
* Cambodia
* China
** Hong Kong S.A.R.
* Colombia
* France
* Gabon
* Germany
* India
* Indonesia
* Iran
* Ireland
* Israel
* Italy
* Jamaica
* Kenya
* Laos
* Mexico
* Myanmar
* Nepal
* Nigeria
* Philippines
* Pakistan
* Russia
* Sri Lanka
* Sweden
* South Africa
* Taiwan
* Tanzania
* Thailand
* Uganda
* United Kingdom
* United States
* Vietnam
Additionally, anecdotal evidence for acid attacks exists in other regions of the world such as South America, Central and North Africa, the Middle East, and Central Asia. However, South Asian countries maintain the highest incidence of acid attacks.
Police in the United Kingdom have noted that many victims are afraid to come forward to report attacks, meaning the true scale of the problem may be unknown. | 4 | Acids + Bases |
The history of the discovery regarding carbohydrates dates back around 10,000 years ago in Papua New Guinea during the cultivation of Sugarcane during the Neolithic agricultural revolution . The term "carbohydrate" was first proposed by German chemist Carl Schmidt (chemist) in 1844. In 1856, glycogen, a form of carbohydrate storage in animal livers, was discovered by French physiologist Claude Bernard. | 6 | Carbohydrates |
Plant mannans have β(1-4) linkages, occasionally with α(1-6) galactose branches, forming galactomannans. They are insoluble and a form of storage polysaccharide. Ivory nut is a source of mannans. An additional type is galactoglucomannan found in soft wood with a mixed mannose/glucose β(1-4) backbone. Many mannans are acetylated and some from marine sources, have sulfate esters side chains.
Yeast and some plants such as conjac and salep have a different type of mannans in their cell wall, with a α(1-6) linked backbone and α(1-2) and α(1-3) linked glucose branches, hence "glucomannan". It is water soluble. It is serologically similar to structures found on mammalian glycoproteins. Detection of mannan leads to lysis in the mannan-binding lectin pathway. | 6 | Carbohydrates |
Shortwave UV lamps are made using a fluorescent lamp tube with no phosphor coating, composed of fused quartz or vycor, since ordinary glass absorbs UV‑C. These lamps emit ultraviolet light with two peaks in the UV‑C band at 253.7 nm and 185 nm due to the mercury within the lamp, as well as some visible light. From 85% to 90% of the UV produced by these lamps is at 253.7 nm, whereas only 5–10% is at 185 nm. The fused quartz tube passes the 253.7 nm radiation but blocks the 185 nm wavelength. Such tubes have two or three times the UV‑C power of a regular fluorescent lamp tube. These low-pressure lamps have a typical efficiency of approximately 30–40%, meaning that for every 100 watts of electricity consumed by the lamp, they will produce approximately 30–40 watts of total UV output. They also emit bluish-white visible light, due to mercury's other spectral lines. These "germicidal" lamps are used extensively for disinfection of surfaces in laboratories and food-processing industries, and for disinfecting water supplies. | 8 | Ultraviolet Radiation |
DPN evolved directly from AFM so it is not a surprise that people often assume that any commercial AFM can perform DPN experiments. In fact, DPN does not require an AFM, and an AFM does not necessarily have real DPN capabilities. There is an excellent analogy with scanning electron microscopy (SEM) and electron beam (E-beam) lithography. E-beam evolved directly from SEM technology and both use a focused electron beam, but it is not possible to perform modern E-beam lithography experiments on a SEM that lacks the proper lithography hardware and software components.
It is also important to consider one of the unique characteristics of DPN, namely its force independence. With virtually all ink/substrate combinations, the same feature size will be patterned no matter how hard the tip is pressing down against the surface. As long as robust SiN tips are used, there is no need for complicated feedback electronics, no need for lasers, no need for quad photo-diodes, and no need for an AFM. | 2 | Tissue Engineering |
Acid attacks in India, like Bangladesh, have a gendered aspect to them: analyses of news reports revealed at least 72% of reported attacks included at least one female victim. However, unlike Bangladesh, India's incidence rate of chemical assault has been increasing in the past decade, with a high 27 reported cases in 2010. Altogether, from January 2002 to October 2010, 153 cases of acid assault were reported in Indian print media while 174 judicial cases were reported for the year of 2000.
The motivation behind acid attacks in India mirrors those in Bangladesh: a study of Indian news reports from January 2002 to October 2010 uncovered that victims rejection of sex or marriage proposals motivated attacks in 35% of the 110 news stories providing a motive for the attack. Acid attacks have also been reported among religious minorities or Muslim women as a form of retaliation or qisas. Notable cases are Sonali Mukherjee in 2003 and Laxmi Agarwal in 2005, whose experience on the ban of acid sales was portrayed in the Bollywood film Chhapaak'.
Police in India were also accused of using acid on individuals, particularly on their eyes, causing blindness to the victims. A well known such case is the Bhagalpur blindings, where police blinded 31 individuals under trial (or convicted criminals, according to some versions) by pouring acid into their eyes. The incident was widely discussed, debated and acutely criticized by several human rights organizations. The Bhagalpur blinding case had made criminal jurisprudence history by becoming the first in which the Indian Supreme Court ordered compensation for violation of basic human rights. | 4 | Acids + Bases |
It can be inferred from these results that the difference in surface tension between these different compounds is the source of different spectra emitted and the time scales in which emission occur. | 0 | Luminescence |
Carbon dioxide is also available as a spray and is used to treat a variety of benign spots. Less frequently, doctors use carbon dioxide "snow" formed into a cylinder or mixed with acetone to form a slush that is applied directly to the treated tissue. | 1 | Cryobiology |
The simplest way of understanding spin waves is to consider the Hamiltonian for the Heisenberg ferromagnet:
where is the exchange energy, the operators represent the spins at Bravais lattice points, is the Landé -factor, is the Bohr magneton and is the internal field which includes the external field plus any "molecular" field. Note that in the classical continuum case and in dimensions the Heisenberg ferromagnet equation has the form
In and dimensions this equation admits several integrable and non-integrable extensions like the Landau-Lifshitz equation, the Ishimori equation and so on. For a ferromagnet and the ground state of the Hamiltonian is that in which all spins are aligned parallel with the field . That is an eigenstate of can be verified by rewriting it in terms of the spin-raising and spin-lowering operators given by:
resulting in
where has been taken as the direction of the magnetic field. The spin-lowering operator annihilates the state with minimum projection of spin along the -axis, while the spin-raising operator annihilates the ground state with maximum spin projection along the -axis. Since
for the maximally aligned state, we find
where N is the total number of Bravais lattice sites. The proposition that the ground state is an eigenstate of the Hamiltonian is confirmed.
One might guess that the first excited state of the Hamiltonian has one randomly selected spin at position rotated so that
but in fact this arrangement of spins is not an eigenstate. The reason is that such a state is transformed by the spin raising and lowering operators. The operator will increase the -projection of the spin at position back to its low-energy orientation, but the operator will lower the -projection of the spin at position . The combined effect of the two operators is therefore to propagate the rotated spin to a new position, which is a hint that the correct eigenstate is a spin wave, namely a superposition of states with one reduced spin. The exchange energy penalty associated with changing the orientation of one spin is reduced by spreading the disturbance over a long wavelength. The degree of misorientation of any two near-neighbor spins is thereby minimized. From this explanation one can see why the Ising model magnet with discrete symmetry has no spin waves: the notion of spreading a disturbance in the spin lattice over a long wavelength makes no sense when spins have only two possible orientations. The existence of low-energy excitations is related to the fact that in the absence of an external field, the spin system has an infinite number of degenerate ground states with infinitesimally different spin orientations. The existence of these ground states can be seen from the fact that the state does not have the full rotational symmetry of the Hamiltonian , a phenomenon which is called spontaneous symmetry breaking. | 7 | Magnetic Ordering |
Treatment of macrophages with lipopolysaccharide (LPS), a major component of the Gram-negative bacteria outer membrane, results in elevated O-GlcNAc in cellular and mouse models. During infection, cytosolic OGT was de-S-nitrosylated and activated. Suppressing O-GlcNAc with DON inhibited the O-GlcNAcylation and nuclear translocation of NF-κB, as well as downstream induction of inducible nitric oxide synthase and IL-1β production. DON treatment also improved cell survival during LPS treatment. | 6 | Carbohydrates |
In many materials, the Curie–Weiss law fails to describe the susceptibility in the immediate vicinity of the Curie point, since it is based on a mean-field approximation. Instead, there is a critical behavior of the form
with the critical exponent . However, at temperatures the expression of the Curie–Weiss law still holds true, but with replaced by a temperature that is somewhat higher than the actual Curie temperature. Some authors call the Weiss constant to distinguish it from the temperature of the actual Curie point. | 7 | Magnetic Ordering |
Phosphor thermometry is a temperature measurement approach that uses the temperature dependence of certain phosphors. For this, a phosphor coating is applied to a surface of interest and, usually, the decay time is the emission parameter that indicates temperature. Because the illumination and detection optics can be situated remotely, the method may be used for moving surfaces such as high speed motor surfaces. Also, phosphor may be applied to the end of an optical fiber as an optical analog of a thermocouple. | 0 | Luminescence |
In a classical picture, nuclei can be understood as hard spheres that repel each other through the Coulomb force but fuse once the two spheres come close enough for contact. Estimating the radius of an atomic nuclei as about one femtometer, the energy needed for fusion of two hydrogen is:
This would imply that for the core of the sun, which has a Boltzmann distribution with a temperature of around 1.4 keV, the probability hydrogen would reach the threshold is , that is, fusion would never occur. However, fusion in the sun does occur due to quantum mechanics. | 3 | Nuclear Fusion |
A black light may also be formed by simply using a UV filter coating such as Wood's glass on the envelope of a common incandescent bulb. This was the method that was used to create the very first black light sources. Although incandescent black light bulbs are a cheaper alternative to fluorescent tubes, they are exceptionally inefficient at producing UV light since most of the light emitted by the filament is visible light which must be blocked. Due to its black body spectrum, an incandescent light radiates less than 0.1% of its energy as UV light. Incandescent UV bulbs, due to the necessary absorption of the visible light, become very hot during use. This heat is, in fact, encouraged in such bulbs, since a hotter filament increases the proportion of UVA in the black-body radiation emitted. This high running-temperature drastically reduces the life of the lamp, however, from a typical 1,000 hours to around 100 hours. | 8 | Ultraviolet Radiation |
The current consensus on the rate of pycnonuclear reactions is not coherent. There are currently a lot of uncertainties to consider when modelling the rate of pycnonuclear reactions, especially in spaces with high numbers of free particles. The primary focus of current research is on the effects of crystal lattice deformation and the presence of free neutrons on the reaction rate. Every time fusion occurs, nuclei are removed from the crystal lattice - creating a defect. The difficulty of approximating this model lies within the fact that the further changes occurring to the lattice and the effect of various deformations on the rate are thus far unknown. Since neighbouring lattices can affect the rate of reaction too, negligence of such deformations could lead to major discrepancies. Another confounding variable would be the presence of free neutrons in the crusts of neutron stars. The presence of free neutrons could potentially affect the Coulomb barrier, making it either taller or thicker. A study published by D.G. Yakovlev in 2006 has shown that the rate calculation of the first pycnonuclear fusion of two nuclei in the crust of a neutron star can have an uncertainty magnitude of up to seven. In this study, Yakovlev also highlighted the uncertainty in the threshold of pycnonuclear fusion (e.g., at what density it starts), giving the approximate density required for the start of pycnonuclear fusion of g cm, arriving at a similar conclusion as Haesnel and Zdunik. According to Haesnel and Zdunik, additional uncertainty of rate calculations in neutron stars can also be due to uneven distribution of the crustal heating, which can impact the thermal states of neutron stars before and after accretion.
In white dwarfs and neutron stars, the nuclear reaction rates can not only be affected by pycnonuclear reactions but also by the plasma screening of the Coulomb interaction. A Ukrainian Electrodynamic Research Laboratory "Proton-21", established that by forming a thin electron plasma layer on the surface of the target material, and, thus, forcing the self-compression of the target material at low temperatures, they could stimulate the process of pycnonuclear fusion. The startup of the process was due to the self-contracting plasma "scanning" the entire volume of the target material, screening the Coulomb field. | 3 | Nuclear Fusion |
UVGI can be used to disinfect air with prolonged exposure. In the 1930s and 40s, an experiment in public schools in Philadelphia showed that upper-room ultraviolet fixtures could significantly reduce the transmission of measles among students. In 2020, UVGI is again being researched as a possible countermeasure against COVID-19.
UV and violet light are able to neutralize the infectivity of SARS-CoV-2. Viral titers usually found in the sputum of COVID-19 patients are completely inactivated by levels of UV-A and UV-B irradiation that are similar to those levels experienced from natural sun exposure. This finding suggests that the reduced incidence of SARS-COV-2 in the summer may be, in part, due to the neutralizing activity of solar UV irradiation.
Various UV-emitting devices can be used for SARS-CoV-2 disinfection, and these devices may help in reducing the spread of infection. SARS-CoV-2 can be inactivated by a wide range of UVC wavelengths, and the wavelength of 222 nm provides the most effective disinfection performance.
Disinfection is a function of UV intensity and time. For this reason, it is in theory not as effective on moving air, or when the lamp is perpendicular to the flow, as exposure times are dramatically reduced. However, numerous professional and scientific publications have indicated that the overall effectiveness of UVGI actually increases when used in conjunction with fans and HVAC ventilation, which facilitate whole-room circulation that exposes more air to the UV source. Air purification UVGI systems can be free-standing units with shielded UV lamps that use a fan to force air past the UV light. Other systems are installed in forced air systems so that the circulation for the premises moves microorganisms past the lamps. Key to this form of sterilization is placement of the UV lamps and a good filtration system to remove the dead microorganisms. For example, forced air systems by design impede line-of-sight, thus creating areas of the environment that will be shaded from the UV light. However, a UV lamp placed at the coils and drain pans of cooling systems will keep microorganisms from forming in these naturally damp places. | 8 | Ultraviolet Radiation |
The sperm and the egg are incubated together at a ratio of about 75,000:1 in a culture media in order for the actual fertilisation to take place. A review in 2013 came to the result that a duration of this co-incubation of about 1 to 4 hours results in significantly higher pregnancy rates than 16 to 24 hours. In most cases, the egg will be fertilised during co-incubation and will show two pronuclei. In certain situations, such as low sperm count or motility, a single sperm may be injected directly into the egg using intracytoplasmic sperm injection (ICSI). The fertilised egg is passed to a special growth medium and left for about 48 hours until the embryo consists of six to eight cells.
In gamete intrafallopian transfer, eggs are removed from the woman and placed in one of the fallopian tubes, along with the mans sperm. This allows fertilisation to take place inside the womans body. Therefore, this variation is actually an in vivo fertilisation, not in vitro. | 1 | Cryobiology |
The concept dates to the 1950s, and was strongly advocated by Hans Bethe during the 1970s. At that time the first powerful fusion experiments were being built, but it would still be many years before they could be economically competitive. Hybrids were proposed as a way of greatly accelerating their market introduction, producing energy even before the fusion systems reached break-even. However, detailed studies of the economics of the systems suggested they could not compete with existing fission reactors.
The idea was abandoned and lay dormant until the 2000s, when the continued delays in reaching break-even led to a brief revival around 2009. These studies generally concentrated on the nuclear waste disposal aspects of the design, as opposed to the production of energy. The concept has seen cyclical interest since then, based largely on the success or failure of more conventional solutions like the Yucca Mountain nuclear waste repository
Another major design effort for energy production was started at Lawrence Livermore National Laboratory (LLNL) under their LIFE program. Industry input led to the abandonment of the hybrid approach for LIFE, which was then re-designed as a pure-fusion system. LIFE was cancelled when the underlying technology, from the National Ignition Facility, failed to reach its design performance goals.
Apollo Fusion, a company founded by Google executive Mike Cassidy in 2017, was also reported to be focused on using the subcritical nuclear fusion-fission hybrid method. Their web site is now focussed on their hall effect thrusters, and mentions fusion only in passing.
On 2022, September 9, Professor Peng Xianjue of the Chinese Academy of Engineering Physics announced that the Chinese government had approved the construction of the worlds largest pulsed-powerplant - the Z-FFR, namely Z(-pinch)-Fission-Fusion Reactor- in Chengdu, Sichuan province. Neutrons produced in a Z-pinch facility (endowed with cylindrical symmetry and fuelled with deuterium and tritium) will strike a coaxial blanket including both uranium and lithium isotopes. Uranium fission will boost the facilitys overall heat output by 10 to 20 times. Interaction of lithium and neutrons will provide tritium for further fueling. Innovative, quasi-spherical geometry near the core of Z-FFR leads to high performance of Z-pinch discharge. According to Prof. Xianjue, this will considerably speed up the use of fusion energy and prepare it for commercial power production by 2035. | 3 | Nuclear Fusion |
Sensor-based sorting can be applied to separate the coarse fraction of the run-of-mine material according to its characteristics. Possible separation criteria are grade, mineralogy, grade and grindability amongst others. Treating different ore types separately results either in an optimised cash flow in the sense, that revenue ist shifted to an earlier point in time, or increased overall recovery which translates to higher productivity and thus revenue. If two separate plant lines are installed, the increased productivity must compensate for the overall higher capital expenditure and operating costs. | 5 | Separation Processes |
Although direct bandgap semiconductors such as GaAs or GaN are most easily examined by these techniques, indirect semiconductors such as silicon also emit weak cathodoluminescence, and can be examined as well. In particular, the luminescence of dislocated silicon is different from intrinsic silicon, and can be used to map defects in integrated circuits.
Recently, cathodoluminescence performed in electron microscopes is also being used to study surface plasmon resonances in metallic nanoparticles. Surface plasmons in metal nanoparticles can absorb and emit light, though the process is different from that in semiconductors. Similarly, cathodoluminescence has been exploited as a probe to map the local density of states of planar dielectric photonic crystals and nanostructured photonic materials. | 0 | Luminescence |
In the case of a single stress acting upon a single magnetic domain, the magnetic strain energy density can be expressed as:
where is the magnetostrictive expansion at saturation, and is the angle between the saturation magnetization and the stress's direction.
When and are both positive (like in iron under tension), the energy is minimum for = 0, i.e. when tension is aligned with the saturation magnetization. Consequently, the magnetization is increased by tension. | 7 | Magnetic Ordering |
Overexposure to UV‑B radiation not only can cause sunburn but also some forms of skin cancer. However, the degree of redness and eye irritation (which are largely not caused by UV‑A) do not predict the long-term effects of UV, although they do mirror the direct damage of DNA by ultraviolet.
All bands of UV radiation damage collagen fibers and accelerate aging of the skin. Both UV‑A and UV‑B destroy vitamin A in skin, which may cause further damage.
UVB radiation can cause direct DNA damage. This cancer connection is one reason for concern about ozone depletion and the ozone hole.
The most deadly form of skin cancer, malignant melanoma, is mostly caused by DNA damage independent from UV‑A radiation. This can be seen from the absence of a direct UV signature mutation in 92% of all melanoma. Occasional overexposure and sunburn are probably greater risk factors for melanoma than long-term moderate exposure. UV‑C is the highest-energy, most-dangerous type of ultraviolet radiation, and causes adverse effects that can variously be mutagenic or carcinogenic.
In the past, UV‑A was considered not harmful or less harmful than UV‑B, but today it is known to contribute to skin cancer via indirect DNA damage (free radicals such as reactive oxygen species). UV‑A can generate highly reactive chemical intermediates, such as hydroxyl and oxygen radicals, which in turn can damage DNA. The DNA damage caused indirectly to skin by UV‑A consists mostly of single-strand breaks in DNA, while the damage caused by UV‑B includes direct formation of thymine dimers or cytosine dimers and double-strand DNA breakage. UV‑A is immunosuppressive for the entire body (accounting for a large part of the immunosuppressive effects of sunlight exposure), and is mutagenic for basal cell keratinocytes in skin.
UVB photons can cause direct DNA damage. UV‑B radiation excites DNA molecules in skin cells, causing aberrant covalent bonds to form between adjacent pyrimidine bases, producing a dimer. Most UV-induced pyrimidine dimers in DNA are removed by the process known as nucleotide excision repair that employs about 30 different proteins. Those pyrimidine dimers that escape this repair process can induce a form of programmed cell death (apoptosis) or can cause DNA replication errors leading to mutation.
As a defense against UV radiation, the amount of the brown pigment melanin in the skin increases when exposed to moderate (depending on skin type) levels of radiation; this is commonly known as a sun tan. The purpose of melanin is to absorb UV radiation and dissipate the energy as harmless heat, protecting the skin against both direct and indirect DNA damage from the UV. UV‑A gives a quick tan that lasts for days by oxidizing melanin that was already present and triggers the release of the melanin from melanocytes. UV‑B yields a tan that takes roughly 2 days to develop because it stimulates the body to produce more melanin. | 8 | Ultraviolet Radiation |
Though comprehensive statistics on acid attacks in South America are sparse, a recent study investigating acid assault in Bogota, Colombia, provides some insight for this region. According to the article, the first identified survivor of acid violence in Bogota was attacked in 1998. Since then reported cases have been increasing with time. The study also cited the Colombian Forensics Institute, which reported that 56 women complained of aggression by acid in 2010, 46 in 2011, and 16 during the first trimester of 2012. The average age of survivors was about 23 years old, but ranged from 13 to 41 years.
The study reported a male-to-female victim ratio of 1:30 for acid assault in Bogota, Colombia, although recent reports show the ratio is closer to 1:1. Reasons behind these attacks usually stemmed from poor interpersonal relationships and domestic intolerance toward women. Moreover, female victims usually came from low socioeconomic classes and had low education. The authors state that the prevalence of acid attacks in other areas of South America remains unknown due to significant underreporting.
On 27 March 2014, a woman named Natalia Ponce de León was assaulted by Jonathan Vega, who threw a liter of sulphuric acid on her face and body. Vega, a former neighbor, was reported to have been "obsessed" with Ponce de León and had been making death threats against her after she turned down his proposal for a relationship. 24% of her body was severely burned as a result of the attack. Ponce de León has undergone 15 reconstruction surgeries on her face and body since the attack.
Three years before the attack took place, Colombia reported one of the highest rates of acid attack<nowiki/>s per capita in the world. However, there was not an effective law in place until Ponce de León's campaign took off in the months after her attack. The new law, which is named after her, defines acid attacks as a specific crime and increases maximum sentences to 50 years in prison for convicted offenders. The law also seeks to provide victims with better state medical care including reconstructive surgery and psychological therapy. Ponce de León expressed hope that the new law would act as a deterrent against future attacks. | 4 | Acids + Bases |
In dilute aqueous solution, the predominant acid species is the hydrated hydrogen ion HO (or more accurately [H(OH)]). In this case H and H are equivalent to pH values determined by the buffer equation or Henderson-Hasselbalch equation.<br>
However, an H value of −21 (a 25% solution of SbF in HSOF) does not imply a hydrogen ion concentration of 10 mol/dm: such a "solution" would have a density more than a hundred times greater than a neutron star. Rather, H = −21 implies that the reactivity (protonating power) of the solvated hydrogen ions is 10 times greater than the reactivity of the hydrated hydrogen ions in an aqueous solution of pH 0. The actual reactive species are different in the two cases, but both can be considered to be sources of H, i.e. Brønsted acids. never exists on its own in a condensed phase, as it is always solvated to a certain extent. The high negative value of H in SbF/HSOF mixtures indicates that the solvation of the hydrogen ion is much weaker in this solvent system than in water. Other way of expressing the same phenomenon is to say that SbF·FSOH is a much stronger proton donor than HO. | 4 | Acids + Bases |
Twenty irregular tetrahedra pack with a common vertex in such a way that the twelve outer vertices form a regular icosahedron. Indeed, the icosahedron edge length l is slightly longer than the circumsphere radius r (l ≈ 1.05r). There is a solution with regular tetrahedra if the space is not Euclidean, but spherical. It is the polytope {3,3,5}, using the Schläfli notation, also known as the 600-cell.
There are one hundred and twenty vertices which all belong to the hypersphere S with radius equal to the golden ratio (φ = ) if the edges are of unit length. The six hundred cells are regular tetrahedra grouped by five around a common edge and by twenty around a common vertex. This structure is called a polytope (see Coxeter) which is the general name in higher dimension in the series containing polygons and polyhedra. Even if this structure is embedded in four dimensions, it has been considered as a three dimensional (curved) manifold. This point is conceptually important for the following reason. The ideal models that have been introduced in the curved Space are three dimensional curved templates. They look locally as three dimensional Euclidean models. So, the {3,3,5} polytope, which is a tiling by tetrahedra, provides a very dense atomic structure if atoms are located on its vertices. It is therefore naturally used as a template for amorphous metals, but one should not forget that it is at the price of successive idealizations. | 7 | Magnetic Ordering |
The tautomer, known as cyanic acid, HOCN, in which the oxygen atom is protonated exists in equilibrium with isocyanic acid to the extent of about 3%. The vibrational spectrum is indicative of the presence of a triple bond between the nitrogen and carbon atoms. | 4 | Acids + Bases |
Not all cells undergo a complete EMT, i.e. losing their cell-cell adhesion and gaining solitary migration characteristics. Instead, most cells undergo partial EMT, a state in which they retain some epithelial traits such as cell-cell adhesion or apico-basal polarity, and gain migratory traits, thus cells in this hybrid epithelial/mesenchymal (E/M) phenotype are endowed with special properties such as collective cell migration. Single-cell tracking contributes to enabling the visualization of morphological transitions during EMT, the discernment of cell migration phenotypes, and the correlation of the heritability of these traits among sister cells. Two mathematical models have been proposed, attempting to explain the emergence of this hybrid E/M phenotype, and its highly likely that different cell lines adopt different hybrid state(s), as shown by experiments in MCF10A, HMLE and H1975 cell lines. Although a hybrid E/M state has been referred to as metastable or transient, recent experiments in H1975 cells suggest that this state can be stably maintained by cells. | 2 | Tissue Engineering |
Laser-based bioprinting can be split into two major classes: those based on cell transfer technologies or photo-polymerization. In cell transfer laser printing, a laser stimulates the connection between energy-absorbing material (e.g. gold, titanium, etc.) and the bioink. This donor layer vaporizes under the laser's irradiation, forming a bubble from the bioink layer which gets deposited from a jet. Photo-polymerization techniques rather use photoinitiated reactions to solidify the ink, moving the beam path of a laser to induce the formation of a desired construct. Certain laser frequencies paired with photopolymerization reactions can be carried out without damaging cells in the material. | 2 | Tissue Engineering |
The mechanism underlying this phenomenon is not fully understood. However, the phenomenon of persistent luminescence must not be mistaken for fluorescence and phosphorescence (see for definitions and ). Indeed, in fluorescence, the lifetime of the excited state is in the order of a few nanoseconds and in phosphorescence, even if the lifetime of the emission can reach several seconds, the reason of the long emission is due to the deexcitation between two electronic states of different spin multiplicity. For persistent luminescence, it has been known for a long time that the phenomenon involved energy traps (such as electron or hole trap) in a material which are filled during the excitation. After the end of the excitation, the stored energy is gradually released to emitter centers which emit light usually by a fluorescence-like mechanism. | 0 | Luminescence |
For projection televisions, where the beam power density can be two orders of magnitude higher than in conventional CRTs, some different phosphors have to be used.
For blue color, is employed. However, it saturates. can be used as an alternative that is more linear at high energy densities.
For green, a terbium-activated ; its color purity and brightness at low excitation densities is worse than the zinc sulfide alternative, but it behaves linear at high excitation energy densities, while zinc sulfide saturates. However, it also saturates, so or can be substituted. is bright but water-sensitive, degradation-prone, and the plate-like morphology of its crystals hampers its use; these problems are solved now, so it is gaining use due to its higher linearity.
is used for red emission. | 0 | Luminescence |
Much research has been done on glycogen degradation through studying the structure and function of glycogen phosphorylase, the key regulatory enzyme of glycogen degradation. On the other hand, much less is known about the structure of glycogen synthase, the key regulatory enzyme of glycogen synthesis. The crystal structure of glycogen synthase from Agrobacterium tumefaciens, however, has been determined at 2.3 A resolution. In its asymmetric form, glycogen synthase is found as a dimer, whose monomers are composed of two Rossmann-fold domains. This structural property, among others, is shared with related enzymes, such as glycogen phosphorylase and other glycosyltransferases of the GT-B superfamily. Nonetheless, a more recent characterization of the Saccharomyces cerevisiae (yeast) glycogen synthase crystal structure reveals that the dimers may actually interact to form a tetramer. Specifically, The inter-subunit interactions are mediated by the α15/16 helix pairs, forming allosteric sites between subunits in one combination of dimers and active sites between subunits in the other combination of dimers. Since the structure of eukaryotic glycogen synthase is highly conserved among species, glycogen synthase likely forms a tetramer in humans as well.
Glycogen synthase can be classified in two general protein families. The first family (GT3), which is from mammals and yeast, is approximately 80 kDa, uses UDP-glucose as a sugar donor, and is regulated by phosphorylation and ligand binding. The second family (GT5), which is from bacteria and plants, is approximately 50 kDA, uses ADP-glucose as a sugar donor, and is unregulated. | 6 | Carbohydrates |
In 1832, H.A.L. Wiggers discovered trehalose in an ergot of rye, and in 1859 Marcellin Berthelot isolated it from Trehala manna, a substance made by weevils and named it trehalose.
Trehalose has long been known as an autophagy inducer that acts independently of mTOR. In 2017, research was published showing that trehalose induces autophagy by activating TFEB, a protein that acts as a master regulator of the autophagy-lysosome pathway. | 6 | Carbohydrates |
Dr. Kenneth B. Storey is among the top 2% of highly cited scientists in the world.
*[https://pubmed.ncbi.nlm.nih.gov/?term=storey+kb&sort=date&size=100 PubMed]
* [https://scholar.google.com/citations?user=mzhKxEoAAAAJ&hl=en Google Scholar] | 1 | Cryobiology |
It is believed to be the first compound to have formed in the universe, and is of fundamental importance in understanding the chemistry of the early universe. This is because hydrogen and helium were almost the only types of atoms formed in Big Bang nucleosynthesis. Stars formed from the primordial material should contain HeH, which could influence their formation and subsequent evolution. In particular, its strong dipole moment makes it relevant to the opacity of zero-metallicity stars. HeH is also thought to be an important constituent of the atmospheres of helium-rich white dwarfs, where it increases the opacity of the gas and causes the star to cool more slowly.
HeH could be formed in the cooling gas behind dissociative shocks in dense interstellar clouds, such as the shocks caused by stellar winds, supernovae and outflowing material from young stars. If the speed of the shock is greater than about , quantities large enough to detect might be formed. If detected, the emissions from HeH would then be useful tracers of the shock.
Several locations had been suggested as possible places HeH might be detected. These included cool helium stars, H II regions, and dense planetary nebulae, like NGC 7027, where, in April 2019, HeH was reported to have been detected. | 4 | Acids + Bases |
The Catskill-Delaware Water Ultraviolet Disinfection Facility is a ultraviolet (UV) water disinfection plant built in Westchester County, New York to disinfect water for the New York City water supply system. The compound is the largest ultraviolet germicidal irradiation plant in the world.
The UV facility treats water delivered by two of the citys aqueduct systems, the Catskill Aqueduct and the Delaware Aqueduct, via the Kensico Reservoir. (The citys third supply system, the New Croton Aqueduct, has a separate treatment plant.)
The plant has 56 energy-efficient UV reactors, and cost the city $1.6 billion. Mayor Michael Bloomberg created research groups between 2004-2006 to decide the best and most cost-effective ways to modernize the citys water filtration process, as a secondary stage following the existing chlorination and fluoridation facilities. The UV technology effectively controls microorganisms such as giardia and cryptosporidium' which are resistant to chlorine treatment. The city staff determined that the cheapest alternatives to a UV system would cost over $3 billion. In response to this finding, Bloomberg decided to set up a public competitive contract auction. Ontario based Trojan Technologies won the contract.
The facility treats of water per day. The new facility was originally set to be in operation by the end of 2012. The facility opened on October 8, 2013. | 8 | Ultraviolet Radiation |
One of the challenges of 3D printing organs is to recreate the vasculature required to keep the organs alive. Designing a correct vasculature is necessary for the transport of nutrients, oxygen, and waste. Blood vessels, especially capillaries, are difficult due to the small diameter. Progress has been made in this area at Rice University, where researchers designed a 3D printer to make vessels in biocompatible hydrogels and designed a model of lungs that can oxygenate blood. However, accompanied with this technique is the challenge of replicating the other minute details of organs. It is difficult to replicate the entangled networks of airways, blood vessels, and bile ducts and complex geometry of organs.
The challenges faced in the organ printing field extends beyond the research and development of techniques to solve the issues of multivascularization and difficult geometries. Before organ printing can become widely available, a source for sustainable cell sources must be found and large-scale manufacturing processes need to be developed. Additional challenges include designing clinical trials to test the long-term viability and biocompatibility of synthetic organs. While many developments have been made in the field of organ printing, more research must be conducted. | 2 | Tissue Engineering |
A thermodynamic system is ergodic when, given any (equilibrium) instance of the system, it eventually visits every other possible (equilibrium) state (of the same energy). One characteristic of spin glass systems is that, below the freezing temperature , instances are trapped in a "non-ergodic" set of states: the system may fluctuate between several states, but cannot transition to other states of equivalent energy. Intuitively, one can say that the system cannot escape from deep minima of the hierarchically disordered energy landscape; the distances between minima are given by an ultrametric, with tall energy barriers between minima. The participation ratio counts the number of states that are accessible from a given instance, that is, the number of states that participate in the ground state. The ergodic aspect of spin glass was instrumental in the awarding of half the 2021 Nobel Prize in Physics to Giorgio Parisi.
For physical systems, such as dilute manganese in copper, the freezing temperature is typically as low as 30 kelvins (−240 °C), and so the spin-glass magnetism appears to be practically without applications in daily life. The non-ergodic states and rugged energy landscapes are, however, quite useful in understanding the behavior of certain neural networks, including Hopfield networks, as well as many problems in computer science optimization and genetics. | 7 | Magnetic Ordering |
An anode ray ion source typically is an anode coated with the halide salt of an alkali or alkaline earth metal. Application of a sufficiently high electrical potential creates alkali or alkaline earth ions and their emission is most brightly visible at the anode. | 0 | Luminescence |
The oldest known magnetic material, magnetite, is a ferrimagnetic substance. The tetrahedral and octahedral sites of its crystal structure exhibit opposite spin. Other known ferrimagnetic materials include yttrium iron garnet (YIG); cubic ferrites composed of iron oxides with other elements such as aluminum, cobalt, nickel, manganese, and zinc; and hexagonal or spinel type ferrites, including rhenium ferrite, ReFeO, PbFeO and BaFeO and pyrrhotite, FeS.
Ferrimagnetism can also occur in single-molecule magnets. A classic example is a dodecanuclear manganese molecule with an effective spin S = 10 derived from antiferromagnetic interaction on Mn(IV) metal centers with Mn(III) and Mn(II) metal centers. | 7 | Magnetic Ordering |
Osazones are highly coloured and crystalline compounds. Osazones are readily distinguished.
*Maltosazone (from maltose) forms petal-shaped crystals.
*Lactosazone (from lactose) forms powder puff-shaped crystals.
*Galactosazone (from galactose) forms rhombic-plate shaped crystals.
*Glucosazone (from glucose, fructose or mannose) forms broomstick or needle-shaped crystals. | 6 | Carbohydrates |
The purpose of static micromagnetics is to solve for the spatial distribution of the magnetization M at equilibrium. In most cases, as the temperature is much lower than the Curie temperature of the material considered, the modulus |M| of the magnetization is assumed to be everywhere equal to the saturation magnetization M. The problem then consists in finding the spatial orientation of the magnetization, which is given by the magnetization direction vector m = M/M, also called reduced magnetization.
The static equilibria are found by minimizing the magnetic energy,
subject to the constraint |M|=M or |m|=1.
The contributions to this energy are the following: | 7 | Magnetic Ordering |
A handful of studies utilized tissue engineering of heart valves in vivo in animal models and humans. In 2000, Matheny conducted a study in which he used a pig's small intestinal submucosa to replace one pulmonary valve leaflet. Limited studies have also been conducted in a clinical setting. For instance in 2001, Elkins implanted SynerGraft treated decellularized human pulmonary valves in patients. Simon similarly used SynerGraft decellularized pig valves for implantation in children; however, these valves widely failed as there were no host cells but rather high amounts of inflammatory cells found at the scaffold site instead. Studies led by Dohmen, Konertz, and colleagues in Berlin, Germany involved the implantation of a biological pig valve in 50 patients who underwent the Ross operation from 2002 to 2004. Using a decellularized porcine xenograft valve, also called Matrix P, in adults with a median age of 46 years, the aim of the study was to offer a proposal for pulmonary valve replacement. While some patients died postoperatively and had to undergo reoperation, the short-term results appear to be going well as the valve is behaving similarly to a native, healthy valve. One animal trial combined the transcatheter aortic valve replacement (TAVR) procedure with tissue engineered heart valves (TEHVs). A TAVR stent integrated with human cell-derived extracellular matrix was implanted and examined in sheep, in which the valve upheld structural integrity and cell infiltration, allowing the potential clinical application to extend TAVR to younger patients. | 2 | Tissue Engineering |
A spin ice is a magnetic substance that does not have a single minimal-energy state. It has magnetic moments (i.e. "spin") as elementary degrees of freedom which are subject to frustrated interactions. By their nature, these interactions prevent the moments from exhibiting a periodic pattern in their orientation down to a temperature much below the energy scale set by the said interactions. Spin ices show low-temperature properties, residual entropy in particular, closely related to those of common crystalline water ice. The most prominent compounds with such properties are dysprosium titanate (DyTiO) and holmium titanate (HoTiO). The orientation of the magnetic moments in spin ice resembles the positional organization of hydrogen atoms (more accurately, ionized hydrogen, or protons) in conventional water ice (see figure 1).
Experiments have found evidence for the existence of deconfined magnetic monopoles in these materials, with properties resembling those of the hypothetical magnetic monopoles postulated to exist in vacuum. | 7 | Magnetic Ordering |
In the early 2000s, research was undertaken by Sandia National Laboratories, Los Alamos National Laboratory, The University of Florida, Texas A&M University and General Atomics to use direct conversion to extract energy from fission reactions, essentially, attempting to extract energy from the linear motion of charged particles coming off a fission reaction. | 3 | Nuclear Fusion |
The Sylvania Lighting Division in Salem and Danvers, Massachusetts, produced and marketed an EL night light, under the trade name Panelescent at roughly the same time that the Chrysler instrument panels entered production. These lamps have proven extremely reliable, with some samples known to be still functional after nearly 50 years of continuous operation.
Later in the 1960s, Sylvania's Electronic Systems Division in Needham, Massachusetts developed and manufactured several instruments for the Apollo Lunar Module and Command Module using electroluminescent display panels manufactured by the Electronic Tube Division of Sylvania at Emporium, Pennsylvania. Raytheon in Sudbury, Massachusetts manufactured the Apollo Guidance Computer, which used a Sylvania electroluminescent display panel as part of its display-keyboard interface (DSKY). | 0 | Luminescence |
Some children conceived by IVF using anonymous donors report being troubled over not knowing about their donor parent as well any genetic relatives they may have and their family history.
Alana Stewart, who was conceived using donor sperm, began an online forum for donor children called AnonymousUS in 2010. The forum welcomes the viewpoints of anyone involved in the IVF process. Olivia Pratten, a donor-conceived Canadian, sued the province of British Columbia for access to records on her donor fathers identity in 2008. "Im not a treatment, Im a person, and those records belong to me," Pratten said. In May 2012, a court ruled in Prattens favour, agreeing that the laws at the time discriminated against donor children and making anonymous sperm and egg donation in British Columbia illegal.
In the U.K., Sweden, Norway, Germany, Italy, New Zealand, and some Australian states, donors are not paid and cannot be anonymous.
In 2000, a website called Donor Sibling Registry was created to help biological children with a common donor connect with each other.
In 2012, a documentary called Anonymous Fathers Day' was released that focuses on donor-conceived children. | 1 | Cryobiology |