DNA, disruption


Maintaining a certain density range within the same category of motor fuel is required for satisfactory operation of the vehicle. Indeed the automobile manufacturers take this into account in the development of motor fuel feed systems and consequently select the flows for different mechanical parts. Afterwards, in actual operation, a too-high change in density between different motor fuels could disrupt the settings by changing the fuel equivalence ratio.  [c.188]

Polymer chain ends disrupt the orderly fold pattern of the crystal and tend to be excluded from the crystal and relegated to the amorphous portion of the sample.  [c.211]

In most cases, the linear olefias ia the stream are subsequeatiy seat to alkylatioa or polymerisation processes, both of which are seasitive to trace oxygeaates. The UOP ORU process can be used to remove trace dimethyl ether, tert-huty alcohol, and water down to concentrations of a few parts per million. Eigure 14 shows how the UOP MRU and UOP ORU processes are iategrated with the MTBE and downstream plants. The UOP MRU process is a multibed thermal swiag adsorption process that operates ia a cycHc-batch adsorptioa mode. Methanol is preferentially adsorbed over the less polar hydrocarbons. The desorption step is accompHshed by a temperature swiag usiag the reactor feed. The UOP ORU process iavolves Hquid-phase adsorptioa of the remaining trace oxygeaates from the efflueat stream foUowed by vapor-phase desorptioa usiag an external regenerant. Both processes are ia commercial use.  [c.301]

In two-bath processes either the cotton or the acryHc can be dyed first. If the cotton is dyed first cationic dye can form a salt linkage with the sulfonic acid groups on the anionic dye on cotton leading to poor fastness. Heavy shades are best dyed by first dyeiag the acryHc and then dyeiag the cottoa uader alkaline coaditioas. la order to preveat desorptioa of the cationic dye the dyeiag temperature for the cottoa dyeiag must be below the glass-transitioa temperature for the acryHc of 80°C.  [c.366]

Group description A.f Ap Av- Group descripti on A -p Af Av-  [c.387]

When the problem is to disrupt Ughtly bonded clusters or agglomerates, a new aspect of fine grinding enters. This may be iUustrated by the breakdown of pigments to incorporate them in liquid vehicles in the making of paints, and the disruption of biological cells to release soluble produces. Purees, food pastes, pulps, and the like are processed by this type of mill. Dispersion is also associated with the formation of emulsions which are basically two-fluid systems. Syrups, sauces, milk, ointments, creams, lotions, and asphalt and water-paint emulsions are in this categoiy.  [c.1863]

These units have been used to disrupt bacterial cells for release of enzymes. (See Cell Disruption. )  [c.1865]

The DEP of numerous particle types has been studied, and many apphcations have been developed. Particles studied have included aerosols, glass, minerals, polymer molecules, hving cells, and cell organelles. Apphcations developed include filtration, orientation, sorting or separation, characterization, and levitation and materials handhng. Effects of DEP are easily exhibited, especially by large particles, and can be apphed in many useful and desirable ways. DEP effects can, however, be observed on particles ranging in size even down to the molecular level in special cases. Since thermal effects tend to disrupt DEP with molecular-sized particles, they can be controlled only under special conditions such as in molecular beams.  [c.2010]

Upstream and Downstream Units Upstream and downstream units should be notified of the impending test. If the unit test will last over a period of days, analysts should discuss this with the upstream unit to ensure that they are not scheduling activities that could disrupt feed to the unit under study. Analysts should seek the cooperation of the upstream units by requesting as consistent feed as possible. The downstream units shoiild also be notified to ensure that they will be able to absorb the product from the unit under study. For both units, measurements from their instruments will be useflil to confirm those for the unit under study. If this is the case, analysts must work with those operators and supervisors to ensure that the measurements are made.  [c.2558]

Except in cases of localised acute pollution, dead hsh are now seen much more rarely, but there is increasing evidence that their health is being compromised by long-term low-level pollution. At one level this may lead to premature mortality, resulting in a decreased number of breeding seasons and thence fewer offspring. Evidence is now accumulating, however, that even lower levels of pollutants can disrupt the functioning of the endocrine system of hsh, leading to decreases in immune and stress responses, energy metabolism, osmoregulatory ability and reproductive function. Because of their exposure in the aquatic ecosystem, as the major repository of environmental pollutants, hsh can provide an early warning of effects that may later become apparent in other wildlife and ultimately in humans themselves. Indeed, there is increasing evidence that some of the problems found in hsh, including decreased fertility, genital abnormalities, altered behaviour patterns and response to stress and disease, are now appearing in human populations. This review will summarise the main evidence for such changes in hsh exposed both in the laboratory and in polluted habitats to a wide range of the pollutants that now contaminate our environment. References have been kept to the minimum for simplicity and the reader is referred elsewhere for fuller references to much of the data cited.  [c.28]

Mechanisms of Endocrine Disruption. Classical toxicology deals with the effects of chemicals which act by causing damage to the function of the animal cell, and as such they have relatively little tissue specificity. Xenobiotics which disrupt the endocrine system, however, can act via a very wide variety of mechanisms. They can mimic the effect of a natural hormone (agonist), or they can block its action (antagonist). This may cause changes in the response to the hormone at its target site by affecting its ability to bind to receptors, affect its feedback action to the higher sites of endocrine control such as the hypothalamus and pituitary, or alter the hormone-dependent behaviour of the exposed animal. They can also affect the action of key enzymes of biosynthesis and metabolism that will alter circulating hormone levels, or cause structural changes which affect the function of an endocrine gland. The complexity of the issue is clearly seen in Figure 1, where disruption of any single component can cause dysfunction of a whole range of inter-related mechanisms.  [c.33]

Throughout the latter half of this century, there has been growing concern about the potential dangers from anthropogenic chemicals in the environment. Recently, a growing body of evidence has suggested that certain groups of these chemicals can disrupt normal endocrine functions, and that this could constitute a threat to humans and wildlife. Concern initially focused on the ability of some chemicals to mimic the activity of endogenous oestrogens, but the scope has now broadened to include not only the gonads and reproductive system, but also other endocrine glands (e.g. the pituitary, thyroid, thymus and adrenal) and a number of other endocrine-modulated physiological systems, including the immune and neurological systems. Evidence of reproductive abnormalities has been noted in individuals of a number of wildlife populations, although this has usually been restricted to the vicinity of polluted locations, e.g. sites of accidental chemical spillage or close to point sources of effluent discharge. It is also recognised that endocrine disruption could result from exposure to naturally occurring or plant-derived substances, for example compounds in Kraft paper mill effluent.  [c.61]

Figure 1 The major hormones involved in growth and funetion of the fetal/neonatal testis illustrating how exogenous, environmental oestrogens eould disrupt the normal balanee of these meehanisms. Figure 1 The major hormones involved in growth and funetion of the fetal/neonatal testis illustrating how exogenous, environmental oestrogens eould disrupt the normal balanee of these meehanisms.
The only DNA sequence-specific aspect of these hydrophobic contacts is that they exclude G-C base pairs that are, of course, absent from the TATA box. The amino group of guanine (see Chapter 7) would, if present, sterical-ly disrupt or modify the interface. Surprisingly, 12 of the 16 hydrogen bond acceptors of the minor groove (N3 of adenine and 02 of thymine) are buried in this interaction area without forming hydrogen bonds either to protein side chains or to water molecules. Studies of site-directed mutations have shown that burying polar side chains in a hydrophobic environment without satisfying their hydrogen-bonding requirements is energetically unfavorable. Clearly, the large number of energetically favorable hydrophobic interactions between TBP and TATA-box DNA must compensate for these unfavorable interactions in order to achieve binding constants in the nanomolar range.  [c.157]

Binding to Gpy locks the flexible switch regions I and II of Ga into a conformation that firmly binds GDP but is nonproductive for GTP binding and hydrolysis. The replacement of GDP with GTP causes local but dramatic conformational changes to switch regions I and 11, as shown in the Go GTP-yS structure, which disrupt nearly all of the contacts between Gp. and Ga in the switch interface, thereby triggering release of Ga from Gpy (see Figures 13.10 and 13.11).  [c.264]

G() is related to the reversible work of adhesion obtained using contact angle measurements, but in general is greater than W. This is because once an interface is formed and the adhesive solidifies, strain energy is required to mechanically disrupt the interface. This strain energy arises because of the physical connection between the attachment sites between the adhesive and the substrate and the connectivity between this interface and the adhesive bulk.  [c.449]

J. Low molecular weight symmetrical polyester polyols may be liquids as a result of many chain ends that disrupt crystalline packing entirely.  [c.779]

Stiffening groups are beneficial because they provide adhesives with strong cohesive properties. Cohesive strength is promoted because the stiff segments tend to form laterally ordered groups, through which intermolecular bonding occurs. Under stress, the relatively weak intermolecular bond can easily be broken and re-formed, providing a mechanism for relieving the stress without damage to the polymer backbone and consequent adhesive joint degradation. Bonding is improved by the interaction of the polar groups of the stiffening segment with polar functions on the surface of the adherend and by direct covalent bonding with surface-bound hydroxyl functions. This type of bonding is beneficial because it may improve the environmental resistance of the adhesive joint, since HtO ingressing along the interface does not disrupt the relatively strong covalent bond.  [c.1013]

The continuous-spray, parallel-plate design of precipitator is constructed with a rectangular housing. The sprays used in this system to clean the electrostatic collecting plates are located above the electrostatic field. The fine water droplets formed by the sprays are electrostatically deposited on the collecting surfaces. This system does not disrupt the electrostatic field power but does provide a better wetting action than does the intermittent-spray or weir-type unit. The wetting is continuous and uniform. The continuous flushing eliminates wet/dry buildup problems experienced with other types of design. The weir-type systems do not distribute water evenly or continuously. Intermittent spray requires interruption of the gas cleaning cycle in most cases and can be used effectively only when deposit buildup is slow. The continuous wet precipitation has many broad and diverse applications. It is much more versatile and adaptable than its predecessors. An example of the construction is shown in Figure 13.  [c.428]

The effect is more than just a matter of pH. As shown in Fig. XV-14, phospholipid monolayers can be expanded at low pH values by the presence of phosphotungstate ions [123], which disrupt the stmctival order in the lipid film [124]. Uranyl ions, by contrast, contract the low-pH expanded phase presumably because of a type of counterion condensation [123]. These effects caution against using these ions as stains in electron microscopy. Clearly the nature of the counterion is very important. It is dramatically so with fatty acids that form an insoluble salt with the ion here quite low concentrations (10 M) of divalent ions lead to the formation of the metal salt unless the pH is quite low. Such films are much more condensed than the fatty-acid monolayers themselves [125-127].  [c.557]

Figure Al.3.6. An isolated square well (top). A periodie array of square wells (bottom). This model is used iu the Krouig-Peimey deseriptiou of energy bauds iu solids. Figure Al.3.6. An isolated square well (top). A periodie array of square wells (bottom). This model is used iu the Krouig-Peimey deseriptiou of energy bauds iu solids.
Figure 10.2.5. Example of a local RDF descriptoT for proton 6 used in the prediction of chemical shifts (e = 20 A Figure 10.2.5. Example of a local RDF descriptoT for proton 6 used in the prediction of chemical shifts (e = 20 A
Application of an AC voltage of high frequency to a piezoelectric crystal causes faces of the crystal to move back and forth at the same frequency. This is a piezotransducer. If one of the piezocrystal faces is immersed in a liquid, the oscillatory motion transmits longitudinal ultrasound waves into the liquid. At the surface, the longitudinal waves disrupt it as compression and rarefaction waves arrive there. The breakup of the surface forms drops which spray away from the surface. The rate of formation of drops is similar to the frequency of surface disruption. Thus, a 100-kHz ultrasound wave produces about 10- droplets per second. This rate of formation of droplets is some thousands of times greater than their rate of formation in pneumatic nebulizers. Therefore, with normal argon flows, much more material is carried toward the plasma flame per unit time than is the case with pneumatic devices. Even so, there may be a need for a desolvation chamber to remove as much solvent as possible before the droplets or particulates reach the flame, if the performance of the latter is not to be affected. The ultrasonic devices have greater need still for desolvation because of their higher rate of droplet formation and higher rate of transfer of sample solution. However, at the highest frequencies (1 MHz), droplet size is small, and natural desolvation by evaporation is so rapid that a special desolvation chamber becomes unnecessary.  [c.148]

Networks. Image files are typically transferred among many different stages ia the prepress process. This is most oftea doae over a aetwork that connects the various computer work statioas used ia the process. Although the subject of aetworks is beyoad the scope of this article, some discussioa is useful ia understanding prepress workflow. The Hterature coataias a more complete descriptioa (16).  [c.36]

The quaHty, ie, level of impurities, of the fats and oils used in the manufacture of soap is important in the production of commercial products. Fats and oils are isolated from various animal and vegetable sources and contain different intrinsic impurities. These impurities may include hydrolysis products of the triglyceride, eg, fatty acid and mono/diglycerides proteinaceous materials and particulate dirt, eg, bone meal and various vitamins, pigments, phosphatides, and sterols, ie, cholesterol and tocopherol as weU as less descript odor and color bodies. These impurities affect the physical properties such as odor and color of the fats and oils and can cause additional degradation of the fats and oils upon storage. For commercial soaps, it is desirable to keep these impurities at the absolute minimum for both storage stabiHty and finished product quaHty considerations.  [c.150]

Disc Granulators Figure 20-81 shows the elements of a disc granulator. It is also referred to as a pelletizer in the iron-ore industry or a pan granulator in the agricultural chemical industiy. The equipment consists of a rotating, tilted disc or pan with a rim. Sohds and wetting agents are continuously added to the disc. A coating of the feed material builds up on the disc and the thickness of this layer is controlled by scrapers or a plow, which may oscillate mechanically. The surface of the pan may also be lined with expanded metal or an abrasive coating to promote proper lifting and cascading of the pai-tic-ulate bed, although this is generally unnecessary for fine materials. Sohds are typically fed by either volumetric or gravimetric feeders. Gravimetric feeding generally improves granulation performance due to smaller fluctuations in feed rates whicdi act to disrupt rolling action in the pan. Wetting fluids which promote growth are generally applied by a series of single-fluid spray nozzles distributed across the face of the bed. Sohds ed and spray nozzle locations have a pronounced effect on granulation performance and granule structure.  [c.1891]

Overall redox potential of a system determines the amount of energy that cells can derive from their nutrients. When oxygen is present to be the ultimate acceptor of electrons, complete oxidation of organic molecules yields maximum energy and usu ly results in the produc tion of H9O and CO9. However, inside animus, in polluted waters, in the benthos (bottom region) of natural waters, and elsewhere, there is httle or no free oxygen. In these environments, organisms develop that can partially oxidize substrates or can derive a small amount of energy from reactions where some produc ts are oxidized while others are reduced. The pathways for complete oxidation may be absent and the presence of oxygen can disrupt the mechanisms for anaerobic metabohsm so that the cell is quickly killed. The differences in efficiency are striking Aerobic metabolism of one molecule of glucose can generate bona energy as much as 33 molecules of ATP, while anaerobic metabohsm can yield as little as two molecules of ATP. Natural anaerobic processes accumulate compounds such as ethanol, acetoin, acetone, butanol, lactate, and malate. Produc ts of natural aerobic metabolism are water and carbon dioxide, cell mass, and secondary metabohc products such as antibiotics.  [c.2133]

Bubbling Beds In bubbling beds a large proportion of the noncombustible feedstock, mainly sorbent derived, remains in the combustor, forming the bed. Bed depth is maintained by draining off excess materiah Most of the gas in excess of that required for minimum fluidization appears as bubbles (voids), and these cany particles upward in their wake, promoting the rapid vertical mixing within the bed that resiilts in the even temperatures characteristic of FBC units. Bed temperature is controlled by heat transfer to in-bed boiler tubes and/or to the water-wall tubes used to enclose the furnace. Some units have experienced metal loss from these tube surfaces, a combined effect of erosion and abrasion, and suitable protec tion needs to be provided. Protective measures include surface coatings such as plasma-sprayed metal coatings incorporating silicon carbide, and metal fins to disrupt the solids-flow paftern.  [c.2387]

Much of the impetus for the recent upsurge in activity on endocrine disruption was the finding of decreased sperm counts and an increased incidence of genital abnormalities in humans. While some of these findings have been disputed, the much more extensive evidence from studies with fish adds considerable weight to the argument that such changes are occurring and that they are caused by exposure to anthropogenic pollutants rather than to changes in human lifestyle during the last few decades. Although the abnormalities in human populations were attributed to environmental estrogens , and this has been the subject of much popular concern, it is important to realise that there are very many chemicals that affect male reproductive function in fish which have no estrogenic activity. Such chemicals, even if they are not hormone mimics, can either disrupt the activity of the tissues that secrete or metabolise hormones or the receptors for these hormones. A wide variety of chemicals which cause direct changes in endocrine function of isolated tissues can be considered as potential endocrine disrupters, but too frequently there has been a failure to demonstrate that in the intact animal such chemicals act on the endocrine system at concentrations which do not cause either a stress response or are toxic to the animal. Many organochlorine pesticides, for example, are estrogenic, but they also have a very high toxicity and estrogenic action is of little consequence to a dead or dying fish. Even nonylphenol, which has been of such recent concern for its estrogenic  [c.34]

Chemical-mediated immune suppression has been identified from the experimental study of several wildlife species. Harbour seals fed either chemically contaminated fish from the Wadden Sea or imcontaminated fish were found to have differing immune responses, with the exposed group showing lowered immune response to microbial infections and certain types of cancer. "" Mink fed fish taken from below a discharge point for bleached Kraft pulp mill effluent have also shown impaired immune function, " showing that the non-accnmillative chemicals in this effluent can actively disrupt endocrine associated functions.  [c.74]

A lineblender is a mixer placed directly in process piping when mixing times of several seconds are required. Agitation in a lineblender is sufficient to disrupt the flow pattern through the pipe so that one or two stages of mixing are accomplished. Designers must pay particular attention to the pressure drop through this type of mixer when selecting pumps for the piping system.  [c.207]

Notwithstanding the potential benefits of developing an interpenetrated interphase at the interface, there is currently great scientific and technological interest in self-assembled monolayers (SAMs) [8]. This subject is raised here because silanes are one of the two most important SAM classes (alkyl thiols and related compounds are the other). The term self-assembled monolayer has variations in meaning depending on the scientific discipline in which it is used, so an explanation here of its usage in adhesion science is necessary. Self-assembly implies a high degree of order in the assembled monolayer and a considerable degree of permanence to that assembly. The capability of packing laterally into a highly ordered monolayer is usually conferred by the alignment of relatively long alkyl or fluo-roalkyl chains. The permanence issue is usually interpreted to mean chemisorption involving covalent bond formation rather than strong physical adsorption. Thus conventional silane coupling agents, although capable of chemisorption, cannot be considered SAMs because they lack the required degree of ordered structure and normally form multilayers rather than monolayers. Reactive chloro- and alkoxy-functional silanes with longer alkyl or fluoroalkyl chains are capable of packing well together to form self-assembled monolayers on hydroxylated metal, oxide and glass surfaces. Conditions must be carefully controlled to avoid multilayer formation with di- or tri-alkoxy functional silanes. Obviously, this is not a problem with mono-alkoxy functional silanes although the other non-reactive groups on the silane, usually methyl groups, may disrupt the packing of the monolayer.  [c.409]

Thiols with long alkyl or fluoralkyl entities are the other principal class of compounds used to form self-assembled monolayers (SAMs). As with silanes, much of the scientific and technological interest has been in materials that are inert, particularly compounds bearing aliphatic alkyl or fluoroalkyl groups. It is not necessary for a thiol or related compound to carry a functionality capable of bonding to an organic phase in order to qualify as a SAM. However, such functionality is clearly necessary for a coupling SAM. There is a substantial literature concerning such organofunctional SAMs where the functionality, often an olefin, resides at the terminus of the alkyl chain away from the thiol or silane entity, in order to maximize reactivity with the organic phase and disrupt the alkyl chain packing the least. Such materials are used to construct two-dimensional composites where the regularity afforded by the monolayer is more valuable than any enhancement of adhesion that might accrue from a more disordered, thicker interphase region. Thiols are particularly useful for enhancing adhesion to noble metals such as silver or gold, which are inert to most other chemical functionalities.  [c.412]

This particular application provides an excellent example of the extent to which physicians and surgeons must clearly understand the use of tissue adhesives and learn to use them in the most efficacious fashion. Paradoxically this excellent tissue adhesive, fibrin sealant, can actually function as an anti-adhesive. If fibrin sealant is applied to the underlying musculature following a mastectomy and axillary dissection and the overlying skin is rapidly closed and placed on top of the underlying muscle so that the muscle and skin become in contact as the fibrin sealant is initially polymerizing, then the two tissues are effectively glued together. If, however, a period of delay occurs between the application of fibrin sealant to the underlying chest wall musculature and the closure of the skin with apposition of the skin and underlying muscle, so that polymerization is complete before these tissues come in contact, then the fibrin sealant functions as an anti-adhesive. In fact in this setting the fibrin sealant will prevent adhesion and healing of the two tissue layers. It may even create more potential for seroma formation and drainage than would have been present without its use in the first place. It is also important to note that if effective, rapid closure of the wound is achieved so that the skin and underlying muscle tissues are effectively adherent, it is equally important to not inadvertently disrupt this bond by pulling up on the skin at a later time. Disruption of this bond creates a situation in which the fibrin sealant may again function as an anti-adhesive.  [c.1125]

Of obvious importance to aircraft is the smoothness of exterior surfaces. Smooth aerodynamic surfaces reduce aerodynamic drag, resulting in higher airspeeds and increased efficiency. Mechanical fasteners, even countersunk flush fasteners, introduce disruptions in the airflow over the exterior surface. Even the slight deformation of thin sheets around fasteners produces drag. Adhesively bonded structure has no fasteners to disrupt airflow and is more capable of producing the smooth continuous contours that are so common on aircraft.  [c.1131]


See pages that mention the term DNA, disruption : [c.1933]    [c.228]    [c.232]    [c.1079]    [c.172]    [c.119]    [c.449]    [c.130]    [c.999]    [c.1874]    [c.172]    [c.37]    [c.37]    [c.82]    [c.87]    [c.211]   
The organic chemistry of drug synthesis Vol.3 (1984) -- [ c.83 ]