RESOLUTION RESEARCH

From the early days in resolution research, the mathematical decomposition of a single data matrix, no matter the method used, has been known to be subject to ambiguities [1, 2], This means that many pairs of C- and ST-type matrices can be found that reproduce the original data set with the same fit quality. In plain words,... 

Numerical models try to accurately predict the behavior of a jet breaking up. If one wants to exactly solve the full set of equations (Navier-Stokes, energy, etc.) one needs to perform direct numerical simulations (DNS), which requires tremendous computational power. The computational power available today only allows modeling of simple flow with low spatial and temporal resolution. Researchers are therefore required to make approximatimis that simplify the governing equations and thereby reduce the complexity of the system. 

Methylphenidate hydrochloride (Ritalin and Concerta [Novartis, Basel, Switzerland]) (11, Scheme 2.1) is a mild nervous system stimulant that is primarily prescribed for treatment of attention deficit hyperactivity disorder in children. Although it is marketed in its racemic form, it has been reported that the (+) enantiomer is 5 to 38 times more active than its racemate.Although previous syntheses of (+)-methylphenidate involved classic resolution, researchers at Novartis reported an enantioselective synthesis of (+)-methylphenidate in 1997. As depicted in Scheme 2.1, the synthesis began with a diastereoselective... 

Systems, based on a method of inspection of slice by slice, in a number of cases allow to solve put problems. But for obtaining of higher resolution it is necessary to have an opportunity to increase number of inspected slices. It results in significant increasing of collection data time that is inadmissible in some applications. Besides this, the maximum allowable number of researched slices is rigidly limited by hardware opportunities of tomographs, and also by level of emission of x-ray sources. 

The systems of such type have been developed of all last 10 years. We shall bring some characteristics of one of the last development within the framework of European BRITE project, carried out in LETT This 3D cone-beam tomograph is referred to as EVA Bench or Equipment for Voludensimetry Analysis. It is oriented on NDT of industrial products from ceramics and other composites. One of the main task of this tomograph is achievement of high resolution at study of whole internal volume of researched object. For test sample of the size 10mm spatial resolution in 50mm was obtained [14]. 

Light microscopy is of great importance for basic research, analysis in materials science and for the practical control of fabrication steps. Wlien used conventionally it serves to reveal structures of objects which are otherwise mvisible to the eye or magnifying glass, such as micrometre-sized structures of microelectronic devices on silicon wafers. The lateral resolution of the teclmique is detennined by the wavelength of tire light... 

A second approach modifies the CA resist chemistry. Eor example, researchers have introduced basic additives into the resist formulation to minimize the impact of surface contamination of the resist film (82,83). A resist that already contains added base (and consequendy requites a larger imaging dose) should be less affected by the absorption of small amounts of basic contaminants. Systems of this type have been claimed to have improved resolution as well. The rationalization here is that the acid that diffuses into the unexposed regions of the resist film is neutralized and does not contribute to image degradation (84,85). 

The future use of lead may be decided by the resolution of an environmental paradox. Some markets for lead are being phased out because of environmental concerns, eg, the use of tetraethyllead as a gasoline additive. However, a 1990 State of California law and similar laws in nine eastern U.S. states require that 2% of new cars meet 2ero-emission standards in 1998. By 2003 this requirement rises to 10% of new vehicles. Zero emission vehicles are generally accepted to mean electric, ie, battery powered cars, and there is considerable research effort to bring suitable electric vehicles to market by 1998. 

Because the Corey synthesis has been extensively used in prostaglandin research, improvements on the various steps in the procedure have been made. These variations include improved procedures for the preparation of norbomenone (24), alternative methods for the resolution of acid (26), stereoselective preparations of (26), improved procedures for the deiodination of iodolactone (27), alternative methods for the synthesis of Corey aldehyde (29) or its equivalent, and improved procedures for the stereoselective reduction of enone (30) (108—168). For example, a catalytic enantioselective Diels-Alder reaction has been used in a highly efficient synthesis of key intermediate (24) in 92% ee (169). 

Sedimentation analysis is suitable for a wide variety of materials and is used for both quaHty control and research work, such as agglomeration studies (56), and gives well-defined, relatively high resolution results. The technique has been employed in the evaluation of soils, sediments, pigments, fillers, phosphors, clays (qv), minerals, photographic haHdes, and organic particles (57,58). 

Some very high resolution or ultrasensitive spectroscopies emerging as of ca 1996 were beam spectroscopy, multiphoton absorption and ionisation, and frequency-modulation spectroscopy (8). Most of these were used primarily for laboratory research as of the mid-1990s, but eventual appHcation to analytical or sensor appHcations is expected. 

Terpene chemists use mainly gas chromatography in dealing with terpene mixtures in research and development as weU as in quahty control. Capillary gas chromatography with stable bonded-phase columns, the primary analytical method, is also being used more frequendy in the 1990s in product quahty control because its greater resolution is helpful in producing consistent products. 

Despite the progress made in the stereoselective synthesis of (R)-pantothenic acid since the mid-1980s, the commercial chemical synthesis still involves resolution of racemic pantolactone. Recent (ca 1997) synthetic efforts have been directed toward developing a method for enantioselective synthesis of (R)-pantolactone by either chemical or microbial reduction of ketopantolactone. Microbial reduction of ketopantolactone is a promising area for future research. 

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