Unique Uses

Radiation Sources. Ordinarily, electron beams are produced from soHds in vacuo by thermal or field-assisted processes. Plasmas also serve as electron sources, but are more uniquely used as ion sources. Whereas ions can be produced by sputtering and field assisted processes in the absence of plasmas, most ion sources involve plasmas (75). 

One other unique use of MTBE is a medical procedure for the removal of gallstones. This alternative to gallbladder surgery was developed at the Mayo Clinic, and takes advantage of MTBE s capabiUty to quickly dissolve cholesterol. A small incision is used to inject a small amount of MTBE direedy into the gallbladder, and the gallstone can then be removed in solution form (28). 

N2O4 has been extensively studied as a nonaqueous solvent system and it is uniquely useful for preparing anhydrous metal nitrates and nitrato complexes (p. 468). Much of the chemistry can be rationalized in terms of a selfionization equilibrium similar to that observed for... 

Previously, pharmacologists were constrained to the prewired sensitivity of isolated tissues for agonist study. As discussed in Chapter 2, different tissues possess different densities of receptor, different receptor co-proteins in the membranes, and different efficiencies of stimulus-response mechanisms. Judicious choice of tissue type could yield uniquely useful pharmacologic systems (i.e., sensitive screening tissues). However, before the availability of recombinant systems these choices were limited. With the ability to express different densities of human target proteins such as receptors has come a transformation in drug discovery. Recombinant cellular systems can now... 

Aspirin has been remarkably successful in the treatment of the pain and swelling of inflammatory disease and in fact, an estimated 45,000 tons of aspirin are still consumed each year. This success resulted in the syntheses of many other aspirin-like drugs , now referred to as NSAIDs. Aspirin, however, continues to have a unique use in the prevention of thrombosis. Since it produces irreversible inhibition of COX-1 by acetylation of serine at position 530 in the active site, a daily low dose of aspirin will cause a cumulative inhibition of COX-1 in platelets, in the portal circulation. A gradual inhibition of platelet aggregation occurs, reducing the possibility of occlusion of coronary or cerebral vessels by platelet thrombi. However, there are no systemic... 

The refractive index is another very rapid analytical method for determining purity and identity of a substance. It is uniquely useful for quality control monitoring of raw materials and finished products. Many students encounter a refractometer first as a universal detector for high-performance liquid chromatography. 

A final word needs to be said about the supposedly unique features of enzymes, namely, their ability to produce enantiomerically pure products. This is not the place to speculate about the stereospecificity of enzymes, a problem that has been discussed elegantly by Comforth (15). It cannot be denied that the high (>99.9%) enantiomeric purity achieved by enzymes may be uniquely useful in the case of liquid products. However, when crystalline products are obtained in an asymmetric synthesis and the e.e. exceeds 80%, crystallization to enantiomeric purity without excessive loss of material is routinely achieved. 

Yet another technique has been to interview children or adults (such as teachers, Sch fer Smith, 1996) directly, either using questionnaires (Smith et al., 1992), or interviews (Boulton, 1992a). Clearly, people s answers may not be accurate in terms of what we observe, but this method should inform us about what they think and perceive. This has it s own intrinsic interest, and also interest in terms of discrepancies between beliefs and behaviour. In the case of older children, especially adolescents, we may get uniquely useful insights, while bearing in mind the possible distortions due to selective perception and memory, limited insight to motivation, and social desirability in responses, that bear on verbal report data (Boulton, 1992a). 

A first approach to determining explosives on-site might include a combination of specialized sample-collection techniques and subsequent analysis using established IMS technologies or instruments. A second level of development could involve the fabrication of analyzers or analytical systems for an on-site operation and real-time analysis of samples. During the past several years, the first step of development has been demonstrated for explosives in water, in soils, and in a few unique uses. 

A unique use is its ability to locate brain tumors. It is a weak radioisotope able to attach itself to diseased tissue rather than healthy tissue, thus making detection possible. 

A unique use of galhum metal is to glue gemstones to metal jewelry. 

Both antimony-124 and antinomy-125 radioisotopes are used as industrial and metallurgical tracers. A unique use is as a partition or separator between different types of fluids flowing through the same pipeline. Its radioactivity can mark where one type of fluid ends and a different fluid begins. 

A unique use of antimony is to make glass that reflects infrared radiation thus, what is behind the glass cannot be detected by the infrared ray source. 

Most drugs are administered to infants and children for the same therapeutic indications as for adults. However, a few drugs have found unique uses in children. Among these are theophylline and caffeine, which are used to treat apnea of prematurity indomethacin, which closes a patent ductus arteriosus and prostaglandin Ej, which maintains the patency of the ductus arteriosus. Paradoxically, drugs such as phenobarbital, which have a sedating action on adults, may produce hyperactivity in children, and some adult stimulant drugs, such as methyl-phenidate, are used to treat children with hyperactivity. 

The most popular and almost uniquely used equation for representing breakthrough curves is the Wheeler [5] or Wheeler -Jonas equation (Eq.17.4) ... 

The first is metakaolin. This is a partially calcined product that forms above about 500 °C. Only about 10% of the original hydroxyl groups of the kaohnite are retained and much of the crystalline nature of the structure is destroyed. Metakaolin is considerably more reactive than the original kaolin and appears to have an especially reactive surface. It is generally used uncoated and finds most use in plasticised PVC cable insulation, where it is reported as giving uniquely useful electrical properties [86]. 

Pure and doped crystals allow investigation of chromophore interactions and exciton motion. Polarized spectroscopy can be uniquely useful for assigning spectral features and determining orientations of intermediates or products in single crystals, but birefringence often makes the technique less versatile than might have been imagined (Section II.D.4). 

If the use of IF 050), due to the triangle condition, does not yield the desired term, formula (16.69) must be applied once more. Note, that the normalization factors Jr" and Jf " are dependent on both the initial and final term. The method just described makes it possible to construct wave functions for those terms of the /-shell that can be classified uniquely using the characteristics of irreducible representations of the G2 group. 

Miller and co-workers have exploited the highly modular nature of peptide structures, along with mechanistic knowledge regarding peptide conformational control and the principles of nucleophilic catalysis to develop an assortment of synthetically unique, useful, and practical asymmetric transformations [22]. Representative examples are illustrated in Scheme 7. Particularly noteworthy is the asymmetric phosphorylation the resultant phosphate ester can be readily... 

A unique use of arsenic, in the form of arsenic trioxide (AS2O3), is for the treatment of cancer. Relapsed or refractory cases of acute promyelocytic leukemia have been successfully treated with this arsenical. Its use in the United States was approved by the US Food and Drug Administration (FDA) in 2000 (Antman, 2001). 

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