Electrochemical and Spectroscopic Studies on the Interaction of Gatifloxacin,Moxifloxacin and Sparfloxacin with DNA and Their Analytical Applications

The electrochemical oxidation of the three fluoroquinolone drugs FQs: gatifloxacin GTF, moxifloxacin MXF and sparfloxacin SPF, at the bare and DNA‐modified glassy carbon electrodes has been studied by voltammetric techniques. The three FQs showed one irreversible oxidation peak at potential range 0.85–0.91 V vs. Ag‐AgCl, in phosphate buffer of pH 7.0. Differential pulse voltammetry (DPV) and UV‐absorption spectroscopic techniques were employed to probe the interaction between the FQs and calf thymus double stranded deoxyribonucleic acid (ds CT‐DNA). From electrochemical data, the binding constant between DNA and the gatifloxacin, moxifloxacin and sparfloxacin are calculated to be 3228, 2596 and 2857 M^?1 respectively. Based on electrochemical and spectroscopic results, the mode of binding of fluoroquinolone to DNA through combined effect of intercalation and electrostatic interaction was concluded. A detection scheme based on a preconcentration and differential pulse voltammetric (DPV) determination at dsDNA modified glassy carbon electrode (DNA/GCE) was proposed for the trace determination of the studied analytes. The developed method was successfully applied to the determination of the FQs in pharmaceutical formulations.     

Validated HPLC determination of the two fixed dose combinations (chlordiazepoxide hydrochloride and mebeverine hydrochloride; carvedilol and hydrochlorothiazide) in their tablets

Simple, rapid, and selective RP-HPLC methods with UV detection were developed for simultaneous determination of chlordiazepoxide hydrochloride and mebeverine hydrochloride (Mixture I) and carvedilol and hydrochlorothiazide (Mixture II). The chromatographic separation in both mixtures was achieved by using an RP-C8 (octylsilyl) analytical column. For Mixture I, a mobile phase composed of acetonitrile-0.05 M disodium hydrogen phosphate-triethylamine (50 + 50 + 0.2, v/v/v), pH 2.5, was used; the detector wavelength was 247 nm. For Mixture II, the mobile phase consisted of acetonitrile-0.05 M disodium hydrogen phosphate (50 + 50, v/v), pH 4.0, and the detector was set at 220 nm. Quantification of the analytes was based on measuring their peak areas. Both mixtures were resolved in less than 6 min. The reliability and analytical performance of the proposed HPLC procedures were statistically validated with respect to linearity, range, precision, accuracy, selectivity, robustness, LOD, and LOQ. The linear dynamic ranges were 2.5-150 and 2.5-500 microg/mL for chlordiazepoxide HCI and mebeverine HCI, respectively, and 0.25-200 and 0.25-150 microg/mL for carvedilol and hydrochlorothiazide, respectively. The validated HPLC methods were successfully applied to the analysis of their commercial tablet dosage forms, for which no interfering peaks were encountered from common pharmaceutical adjuvants.     

Free Mutual Information for Two Projections

The present paper provides a proof of \(i^*(\mathbb {C}P+\mathbb {C}(I-P); \mathbb {C}Q+\mathbb {C}(I-Q))=-\chi _{{ orb}}(P,Q)\) for two projections P, Q without any extra assumptions. An analytic approach is adopted to the proof, based on a subordination result for the liberation process of symmetries associated with P, Q.     

Photophysical and Complexation Behavior of (4-Dimethylamino-benzylidene)-(4,6-dimethyl-pyrimidin-2-yl)-amine

The absorption and fluorescence characteristics of (4‐dimethylamino‐benzylidene)‐(4,6‐dimethyl‐pyrimidin‐2‐yl)‐amine (SB) have been investigated in different solvents. Both the absorption and emission spectra of SB exhibit red shifts as the solvent polarity increases. This indicats a change in dipole moment of molecules upon excitation as a result of intramolecular charge transfer interaction. The fluorescence quantum yield depends strongly on the properties of the solvents, which was discussed on the bases of positive and negative solvatokinetic effects. The effect of some divalent transition metal ions such as Mn²⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Cd²⁺, and Hg²⁺on the absorption and fluorescence spectra of SB is also investigated. The results were consistent with formation of highly colored metal‐ SB complex which is responsible for the extreme quenching of the fluorescence of SB. The variations of both the formation constant of the complex and Stern‐Volmer constant were correlated with the electronic structure of the used metal ion.     

Coefficient Elimination Algorithm for Low Energy Distributed Arithmetic DCT Architectures

An energy aware DCT (Discrete Cosine Transform) architecture based on the distributed arithmetic concept is proposed. Architectures based on the distributed arithmetic concept are inherently low power as they are multiplication free algorithms. One characteristic of the DCT is that upon transformation signal energies are concentrated in only a few coefficients (less than 25%) with the rest (75%) of the coefficients being insignificant and negligible. One can skip the computation of these terms without seriously affecting the output signal quality. Exploiting this idea, we propose a low energy DCT architecture that can achieve 55% savings in the energy dissipation and 28 db in signal quality. In addition, we propose an adaptive energy aware DCT architecture that trades off energy consumption for signal quality. Using this adaptive architecture, we present a study of the effect of coefficient elimination on energy consumption and signal quality.Tarek K. Darwish received the B.S. and the M.S. degrees in computer engineering from the University of Balamand, Lebanon, and the M.S. degree, also in computer engineering, from the University of Louisiana at Lafayette, in 1996, 1998, and 2001, respectively. He received the Ph.D. degree from The Center for Advanced Computer Studies (CACS) at the University of Louisiana in Dec. 2003.From 2000–2003, he has been a research assistant in the CACS, in the VLSI Research group of M. Bayoumi, University of Louisiana. He has one patent pending. Since 2004 he is working as a senior component design engineer with Intel Corporation. His research interests include low power VLSI system design, Digital signal processing with special interest in image and video processing, computer architecture, and CAD-tools.Magdy A. Bayoumi received the B.Sc. and M.Sc. degrees in electrical engineering from Cairo University, Cairo, Egypt, and the M.Sc. degree in computer engineering from Washington University in St. Louis, MO, and the Ph.D. degree in electrical engineering from the University of Windsor, Windsor, ON, Canada.Currently, he is the Director of the Center for Advanced Computer Studies (CACS), Department Head of the Computer Science Department, the Edmiston Professor of Computer Engineering, and the Lamson Professor of Computer Science at The Center for Advanced Computer Studies, University of Louisiana at Lafayette, where he has been a faculty member since 1985. He has edited and co-edited three books in the area of VLSI Signal Processing. He was an Associate Editor of the Circuits and Devices Magazine and is currently an Associate Editor of Integration, the VLSI Journal, and the Journal of VLSI Signal Processing Systems. He is a Regional Editor for the VLSI Design Journal and on the Advisory Board of the Journal on Microelectronics Systems Integration. He has one patent pending. His research interests include VLSI design methods and architectures, low power circuits and systems, digital signal processing architectures, parallel algorithm design, computer arithmetic, image and video signal processing, neural networks, and wideband network architectures.Dr. Bayoumi received the 2003 IEEE Circuit and Systems Education Award, the 1993 Distinguished Professor Award and the University of Louisiana at Lafayette 1988 Researcher of the Year Award. He was an Associate Editor of the IEEE CIRCUITS AND DEVICES MAGAZINE, the IEEE TRANSACTIONS ON VLSI SYSTEMS, the IEEE TRANSACTIONS ON NEURAL NETWORKS, and the IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS—II: ANALOG AND DIGITAL SIGNAL PROCESSING. From 1991 to 1994, he served on the Distinguished Visitors Program for the IEEE Computer Society, and he was on the Distinguished Lecture Program of the Circuits and Systems Society. He was the Vice President for the technical activities of the IEEE Circuits and Systems Society. He is the general chair of The IEEE International Symposium on Circuits and Systems—ISCAS in 2007. He was the Co-chairman of the Workshop on Computer Architecture for Machine Perception in 1993. He was the General Chairman of the 1994 MWSCAS and Co-chair of 22003 MWSCAS. He was the General Chairman for the 8th Great Lake Symposium on VLSI in 1998. He has been on the Technical Program Committee for ISCAS for several years and he was the Publication Chair for ISCAS99. He was also the General Chairman of the 2000 Workshop on Signal Processing Design and Implementation. He was a founding member of the VLSI Systems and Applications Technical Committee and was its Chairman. He is currently the Chairman of the Technical Committee on Circuits and Systems for Communication, and he was the chair of the Technical Committee on Signal Processing Design and Implementation. He is a member of the Neural Network and the Multimedia Technology Technical Committees. Currently, he is the faculty advisor for the IEEE Computer Student Chapter at the University of Louisiana at Lafayette. He is a fellow IEEE.     

Comparative Account of Bandwidth Efficiency in Optical Burst Switching and Optical Circuit Switching Networks

The performance of Optical Burst Switched (OBS) networks is compared to that of Optical Circuit Switched (OCS) networks in terms of bandwidth efficiency. Two traffic flow models are employed to investigate the effects of traffic grooming, packetization, buffering and burst assembly on bandwidth efficiency and utilization. Traffic is represented by fluid-flow continuous bit streams in the first model and by packet-based discrete flows in the second model. It is shown that the parameters of traffic characteristics and burst assembly have significant impact on the relative bandwidth savings of OBS. The bandwidth efficiency of OBS compared to OCS should not be taken for granted and has to be examined carefully on a case by case basis.     

Weakly representable atom structures that are not strongly representable,with an application to first order logic

Letn > 2. A weakly representable relation algebra that is not strongly representable is constructed. It is proved that the set of all n by n basic matrices forms a cylindric basis that is also a weakly but not a strongly representable atom structure. This gives an example of a binary generated atomic representable cylindric algebra with no complete representation. An application to first order logic is given. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Some results about neat reducts

This is a survey article on the concept of neat reducts. An old venerable idea in algebraic logic, in this paper we show why it is regaining momentum.     

High‐molecular‐weight AB‐type benzoxazines as new precursors for high‐performance thermosets

Novel high‐molecular‐weight polybenzoxazine precursors, namely AB‐type benzoxazine precursors, were synthesized from aminophenols and formaldehyde. Both ¹H NMR and IR confirmed the structure of the precursors, indicating the presence of a cyclic benzoxazine structure in the backbone of the precursors. The weight‐average molecular weight was estimated by size exclusion chromatography to be to in the range of 1300–4500. The precursors gave self‐standing thin films when their solutions were cast in dioxane over glass plates and dried, and upon a gradual thermal cure up to 250 °C, they afforded polybenzoxazine films. The viscoelastic analyses showed that the glass transition temperatures of the polybenzoxazine films obtained from these novel precursors were as high as 260–300 °C. Thermogravimetric analysis results indicated that the onset of decomposition and the char yield of the thermosets derived from these AB‐type precursors were higher than those of traditional polybenzoxazine. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1878–1888, 2007.     

An Efficient Synthesis of O-Methyl Protected Emodin Aldehyde and Emodin Nitrile

An efficient synthesis of tri-O-methylemodin aldehyde was achieved via bromination of tri-O-methylemodin utilizing N-bromosuccinimide yielding the monobromo and dibromo derivatives. Sommelet reaction of the monobromomethyl derivative as well as hydrolysis of the dibromomethyl analog with aqueous silver nitrate afforded the protected aldehyde in good yield. Accordingly, both bromo derivatives can be used even when they are obtained as a mixture of the bromination reaction, which could not be controlled easily to yield the bromo products selectively. From the aldehyde the tri-O-methylemodin nitrile was prepared in a one-pot reaction using hydroxylamine-O-sulfonic acid.