That converts

The application of load in materials produces internal modifications such as crack growth, local plastic deformation, corrosion and phase changes, which are accompanied by the emission of acoustic waves in materials. These waves therefore contain information on the internal behaviour of the material and can be analysed to obtain this information. The waves are detected by the use of suitable sensors, that converts the surface movements of the material into electric signal. These signals are processed, analysed and recorded by an appropriate instrumentation. 

When extremely high resolution is not required, an attractive alternative is found in OPOs. An OPO is based on a nonlinear crystal that converts an input photon into two output photons whose energies add up to the... 

Addition to double bonds is not the only kind of reaction that converts an achiral molecule to a chiral one Other possibilities include substitution reactions such as the formation of 2 chlorobutane by free radical chlorination of butane Here again the prod uct IS chiral but racemic... 

A reasonable mechanism for this observation assumes rate determining ionization of the substrate as the first step followed by a hydride shift that converts the secondary carbocation to a more stable tertiary one... 

The mechanisms of the Fischer esterification and the reactions of alcohols with acyl chlorides and acid anhydrides will be discussed m detail m Chapters 19 and 20 after some fundamental principles of carbonyl group reactivity have been developed For the present it is sufficient to point out that most of the reactions that convert alcohols to esters leave the C—O bond of the alcohol intact... 

The cleavage of ethers is normally earned out under conditions (excess hydrogen halide heat) that convert the alcohol formed as one of the original products to an alkyl halide Thus the reaction typically leads to two alkyl halide molecules... 

Most methods for their preparation convert one class of carboxylic acid derivative to another and the order of carbonyl group stabilization given m Figure 20 1 bears directly on the means by which these transformations may be achieved A reaction that converts one carboxylic acid derivative to another that lies below it m the figure is pracfical a reacfion fhaf converts if fo one fhaf lies above if is nol This is anofher way of saying fhaf one carboxylic acid derivative can be converted to another if the reaction leads to a more stabilized carbonyl group Numerous examples of reacfions of fhis fype will be pre senfed m fhe secfions fhaf follow... 

Isopentenyl pyrophosphate undergoes an enzyme catalyzed reaction that converts It m an equilibrium process to 3 methyl 2 butenyl pyrophosphate (dimethylallyl pyrophosphate)... 

Enantiomers (Section 7 1) Stereoisomers that are related as an object and its nonsupenmposable mirror image Enantioselective synthesis (Section 27 4) Reaction that converts an achiral or racemic starting material to a chiral product in which one enantiomer is present in excess of the other... 

A device that converts a chemical or physical property, such as pH or photon intensity, to an easily measured electrical signal, such as a voltage or current. 

A CCD is a two-dimensional array of silicon photosensors, each photosensor usually being referred to as a pixel. When radiation falls on a pixel, photoelectrons are produced in numbers proportional to the intensity of the radiation. A typical wavelength range to which the CCD is sensitive is 400-1050 nm, but this may be extended down to below 1.5 nm with a phosphor that converts short-wavelength into visible radiation. 

Fig. 7. A bead filter, one of many types of biological filters, shown in association with a laboratory-scale recirculating water system. Small plastic beads inside the fiber glass chamber provide surface area for colonisation by bacteria that convert ammonia to nitrate.

Methane has also been used in aerobic bioreactors that are part of a pump-and-treat operation, and toluene and phenol have also been used as co-substrates at the pilot scale (29). Anaerobic reactors have also been developed for treating trichloroethylene. Eor example, Wu and co-workers (30) have developed a successful upflow anaerobic methanogenic bioreactor that converts trichloroethylene and several other halogenated compounds to ethylene. 

Self-Rephca.tingSystems. Recently, molecules have been synthesized that can catalyze covalent bond-making reactions by forming a noncovalently bonded superstmcture, a maneuver that converts an intermolecular reaction into an intramolecular one. In general, in such systems, two... 

The screw consists of a feed section, a rapid transition section, and a metering section a rounded forward end prevents stagnation. The breaker plate that converts the rotary motion of the melt into smooth, straight flow should have as many holes as possible both ends of each hole should be countersunk for streamlined flow. 

Fuel Cell Catalysts. Euel cells (qv) are electrochemical devices that convert the chemical energy of a fuel direcdy into electrical and thermal energy. The fuel cell, an environmentally clean method of power generation (qv), is more efficient than most other energy conversion systems. The main by-product is pure water. 

Alkylphenols undergo a variety of chemical transformations, involving the hydroxyl group or the aromatic nucleus that convert them to value-added products. 

Phosphorothioates generally protect normal tissues more than tumors. Tumor protection reported in some animal studies can pardy be explained by physiological effects of the particular dmgs, which are specific to rodents (4). WR-2721 does not appear to protect human and most animal tumors, apparentiy because of the low availabiUty of the dmg to tumor cells (4). Many tumors appear to have a reduced capillary density (44), which may mean that these tumors have altered levels of alkaline phosphatase, the enzyme that converts WR-2721 to WR-1065. A reduced abiUty of thiols to protect the hypoxic cells characteristic of many tumors may also contribute to their selectivity for normal tissues. The observation that WR-1065 protects cultured normal human fibroblasts, but not fibrosarcoma tumor cells, suggests that additional factors may contribute to the selectivity of radioprotection by WR-2721 m vivo (18). 

A Acylsarcosinates. Sodium A/-lautoylsarcosinate [7631-98-3] is a good soap-like surfactant. Table 4 gives trade names and properties. The amido group in the hydrophobe chain lessens the interaction with hardness ions. A/-Acylosarcosinates have been used in dentifrices (qv) where they ate claimed to inactivate enzymes that convert glucose to lactic acid in the mouth (57). They ate prepared from a fatty acid chloride and satcosine ... 

Represents EDC necessary for a stoichiometric balance, including that converted to by-products, but no recycled EDC. 

An x-ray area detector can be used to collect the intensities of many reflections at a time. The crystal must be oriented in many different settings with respect to the incident beam but the detector needs to be positioned at only a few positions to collect all of the data. A charge coupled device (CCD) is used as the area detector on the Siemens SMART single crystal diffractometer system. The SMART detector consists of a flat 6-cm circular phosphorescent screen that converts x-ray photons to visible light photons. The screen is coupled to a tapered fiber optics bundle which is then coupled to a one inch by one inch square CCD chip. The CCD chip has 1024 x 1024 pixels each of which stores an electrical charge proportional to the number of... 

Batteries are miniatuie chemical leactois that convert chemical energy into electrical energy on demand. The thermodynamics of battery systems foUow direcdy from that for bulk chemical reactions (10). For the general reaction... 

Immobilized Enzymes. The immobilized enzyme electrode is the most common immobilized biopolymer sensor, consisting of a thin layer of enzyme immobilized on the surface of an electrochemical sensor as shown in Figure 6. The enzyme catalyzes a reaction that converts the target substrate into a product that is detected electrochemicaHy. The advantages of immobilized enzyme electrodes include minimal pretreatment of the sample matrix, small sample volume, and the recovery of the enzyme for repeated use (49). Several reviews and books have been pubHshed on immobilized enzyme electrodes (50—52). 

The principal chemical uses of BTX are illustrated in Figure 1 and Hsted in Table 1 (2). A very wide range of consumer products from solvents to fibers, films, and plastics are based on BTX. The consumption of BTX is approximately in the proportions of 67 5 28, respectively. However, no BTX process gives BTX in these proportions. The economic value of benzene and xylenes (especially -xylene) is normally higher than that of toluene. Because of this, processes that convert toluene to benzene by hydrodealkylation (3) and disproportionate toluene to benzene and xylenes (4) have been commercialized. In addition, reforming processes that emphasize production of either benzene or -xylene [106 2-3] have been described (5). Since these are not classified as BTX processes they are not discussed in detail here. 

Disproportionation of Olefins. Disproportionation or the metathesis reaction offers an opportunity to convert surplus olefins to other desirable olefins. Phillips Petroleum and Institut Fransais du Petrc le have pioneered this technology for the dimerization of light olefins. The original metathesis reaction of Phillips Petroleum was intended to convert propylene to 2-butene and ethylene (58). The reverse reaction that converts 2-butene in the presence of excess ethylene to propylene has also been demonstrated (59). A commercial unit with a capacity of about 136,000 t/yr of propylene from ethylene via 2-butene has been in operation in the Gulf Coast since 1985 (60,61). In this process, ethylene is first dimerized to 2-butene foUowed by metathesis to yield propylene. Since this is a two-stage process, 2-butene can be produced from the first stage, if needed. In the dimerization step, about 95% purity of 2-butene is achieved at 90% ethylene conversion. 

The reactions in the regulated-set cements containing Cjj A3CF2 (note mixed notation) as a principal phase resemble those in ordinary Portiand cements. Initial reaction rates are controlled by ettringite formation. Setting occurs with formation of the monosulfate, along with some transitory lower-limed calcium aluminate hydrates that convert to the monosulfate within a few hours. 

Applications. Epoxy resias constitute over 90% of the matrix resia material used ia advanced composites. In addition, epoxy resias are used ia all the various fabrication processes that convert resias and reinforcements iato composite articles. Liquid resias ia combiaation, mainly, with amines and anhydride are used for filament winding, resia transfer mol ding, and pultmsion. Parts for aircraft, rocket cases, pipes, rods, tennis rackets, ski poles, golf club shafts, and fishing poles are made by one of these processes with an epoxy resia system. 

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