Design and analysis of a compact fast parallel multiplier for high speed DSP applications using novel partial product generator and 4 : 2 compressor

Parallel multiplier is one of the most important building blocks in all the DSP processors, which needs faster computations. To reduce the total transistor count in a multiplier we have proposed two new approaches. The first approach is using a 26 transistor booth encoder and a 8-transistor/partial-product booth selector to generate partial products. The second approach proposes a new circuit for 4 : 2 compressors. The booth encoder and booth selector reported here are the smallest in transistor count, but comparable to the best delay with less power consumption. This paper describes a comparison of a compact 16 × 16 parallel multiplier using the new circuit components. This shows a transistor count advantage of 27% and 52% in partial product generation and partial product accumulation, respectively.     

On the existence of periodic solutions for differential inclusions

In this paper we study the existence of periodic solutions for differential inclusions. We prove existence theorems under various sets of hypotheses for both the nonconvex and convex problems. Also we show the existence of extreme solutions. Some feedback control systems are also considered.     

Determination of optical density at the center of an absorption line contour from the spacing between the frequencies of the two-component radiation spectrum of a laser having a phase-polarization selector

A method for determining optical density at the center of an atomic absorption line contour from the spacing between the components of the two-frequency generation spectrum of a laser with a phase-polarization selector is suggested. It is shown that the method makes it possible to measure the largest possible optical densities, but it is not suitable for measuring optical densities smaller than unity. Optical densities at the center of the D-lines of sodium are measured experimentally. A good agreement between experimental and predicted data is obtained. Institute of Molecular and Atomic Physics of the Academy of Sciences of Belarus, 70, F. Skorina Ave., Minsk, 220072, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 6, pp. 738–743, November–December, 1997.     

Molecular evolution using intramolecular acyl migration on myo-inositol benzoates with thermodynamic and kinetic selectors

A molecular evolution model was successfully demonstrated by combining the intramolecular acyl migration on inositol tribenzoates and boron selectors. The addition of boric acid to 12 members of DCL (dynamic combinatorial library) induced the dramatic amplification of myo-I(2,4,6)Bz(3) (1) with up to 94 % under thermodynamic (see Figure 1 c) control while a portion of phenyl boronic acid caused two significant different distributions: under kinetic control, the pre-equilibrium of DCL shifted to induce the exclusive amplification of 1,4,6-tribenzoyl myo-inositol (7) with decrease of other members up to 82 % from the mixture (see Figure 2 b), and changed gradually to form 2,4,6-tribenzoyl myo-inositol (1) with up to 96 % under thermodynamic control (Figure 2 c).     

Polymethacrylate-type monoliths functionalized with chiral amino phosphonic acid-derived strong cation exchange moieties for enantioselective nonaqueous capillary electrochromatography and investigation of the chemical composition of the monolithic polymer

In situ prepared monolithic poly(glycidyl methacrylate-co-ethylene dimethacrylate) (poly(GMA-co-EDMA)) capillary columns were activated to reactive thiol-monoliths and subsequently functionalized with (S)-N-(4-allyloxy-3,5-dichlorobenzoyl)-2-amino-3,3-dimethylbutanephosphonic acid as chiral selector by radical addition to afford enantioselective strong cation exchanger (SCX) capillary columns (100 microm inner diameter (ID)). These monolithic capillaries were devised for the enantioseparation of chiral bases by nonaqueous and aqueous capillary electrochromatography (CEC) and the results obtained for mefloquine and its tert-butylcarbamate as test compounds were compared to those obtained with particulate silica-based analogs (packed columns). Despite abolishment of nonspecific ionic interactions between the cationic solutes and residual silanols that may diminish separation factors of the silica-based chiral SCX particles, the poly(GMA-co-EDMA)-supported SCX monolith did not, as expected, show better enantioselectivities, which was assumed to be due to detrimental nonspecific interactions between the analytes and the lipophilic polymer backbone. In order to minimize these unfavorable contributions, less lipophilic monoliths were developed by copolymerization of different amounts of the hydrophilic monomer 2-hydroxyethyl methacrylate (HEMA) with GMA and EDMA, leading to GMA-co-HEMA-co-EDMA-terpolymeric monoliths. By this increase of the hydrophilicity of the monolithic support the enantioselectivity of the resultant SCX stationary phase could be enhanced and reached values comparable to the packed silica-based enantioselective SCX capillaries. Additionally, the mobile phase composition and other variables were examined and it could be shown that the separation factors are considerably affected by diverse parameters such as acetonitrile-methanol ratio and type and concentration of the counterion. Mefloquine enantiomers could be separated with alpha-values up to 1.56 and a maximum plate count of ca. 60,000 m(-1) could be achieved.     

Recent advances in peptide chiral selectors for electrophoresis and liquid chromatography

The application of peptides in chiral separations using techniques such as capillary electrophoresis (CE), electrokinetic capillary chromatography (EKC) and liquid chromatography is the focus of this review. Methods for finding peptide selectors using combinatorial library approaches are discussed, as well as recent advances in the use of peptides as general chiral selectors for electrophoresis and liquid chromatography. One example shows the effectiveness of polymeric dipeptide surfactants as general chiral selectors for electrophoresis. Another example shows the versatility of oligoproline chiral stationary phases, exhibiting resolution for a number of racemic analytes comparable to other well-established chiral stationary phases.     

Remarks on Radial Centres of Convex Bodies

The paper concerns a family of selectors for convex bodies in Rⁿ, radial centre maps, defined in the article of M. Moszyńska, Looking for selectors of star bodies, Geom. Dedicata 81 (2000), 131–147. A radial centre of a convex body A is the maximizer of a suitable generalized dual volume of A. We give physical interpretations of the notion of radial centre and study its geometric properties. We prove that these selectors are continuous with respect to the Hausdorff metric and solve the problem of direct additivity for radial centre of order α, which corresponds to the dual volume of order α. Mathematics Subject Classifications (2005) 52A20, 52A40, 51P05, 85A25, 86A20.     

Chiral separations on multichannel microfluidic chips

Chiral separations of FITC-labeled basic drugs on multichannel microfluidic chips with LIF detector were investigated. A preliminary screening procedure for seven neutral CDs was performed under optimized conditions for chiral separations of three FITC-labeled drugs (baclofen, norfenefrine, and tocainide) on a mono-channel microfluidic chip. According to the results of screening, FITC-baclofen and FITC-norfenefrine as well as two chiral selectors including gamma-CD and dimethyl-beta-CD (DM-beta-CD) were selected as models to perform chiral separations on a two-channel chip. FITC-baclofen enantiomers were separated completely by gamma-CD in one channel, while resolution of FITC-norfenefrine enantiomers was achieved by DM-beta-CD in the other channel in the same run. Furthermore, the feasibility of using one chiral selector to separate multiple chiral samples was studied on a four-channel chip. These results show that multichannel chip has a potential for chiral high-throughput screening.     

手性选择剂在色谱分析中的应用

本文综述近年来在光学异构体分离领域中所涉及的主要技术,如高效液相色谱、电色谱、气相色谱及其他色谱法中所使用的常见手性选择性。它们包括环糊精、冠醚、抗菌素、蛋白质、多糖、氨基酸、表面活性剂和分子模板高聚物及其相关的衍生物。     

Determination of the enantiomeric purity of 2-(2′-carboxy-3′-phenylcyclopropyl)glycines by chiral capillary electrophoresis

Summary A fast and practical chiral capillary electrophoretic method has been developed for determination of the enantiomeric purity of 2-(2′-carboxy-3′-phenylcyclopropyl)glycine (PCCG) compounds. In particular, the isomer PCCG-13, a potent selective and competitive antagonist at phospholipaseD-coupled metabotropic glutamate receptors (mGluRs), was completely resolved from its enantiomer PCCG-15 by use of dimethyl-β-cyclodextrin (DMCD) as chiral selector. pH 9.0 running buffer containing 2-amino-2-methyl-1,3-propanediol (AMPD; 100mM) was a suitable medium enabling resolution of the enantiomers in a short (32.5 cm total length) poly(vinyl alcohol) (PVA)-coated capillary. Because of the suppression of the electroosmotic flow and the good peak shape, baseline resolution of the enantiomers was obtained by use of the optimum concentration of chiral selector. For quantitative purposes at impurity levels, high sample loading was required and adequate separation was obtained in the presence of 80 mM DMCD. This CE method enabled quantification of 0.3% m/m of undesired enantiomer in PCCG-13; the samples analyzed, obtained from enantioselective synthesis, proved to be of high enantiomeric purity.