Synthesis of Novel Substituted Tetrahydropyrimidine Derivatives and Evaluation of Their Pharmacological and Antimicrobial Activities

Tetrahydropyrimidine derivative 1 was employed as intermediate compound, which in turn was allowed to react with different electrophilic and nucleophilic reagents to synthesize new polyfunctionalized series of substituted pyrimidine‐2‐thione derivatives. Structures of the newly synthesized compounds have been elucidated by spectroscopic data and elemental analyses. The pharmacological and antimicrobial activities of synthesized products have been evaluated as drug candidates.     

Optical soliton perturbation for Gerdjikov–Ivanov equation via two analytical techniques

This paper employs two integration procedures to obtain soliton solutions to the perturbed Gerdjikov–Ivanov equation. They are G′/G²–expansion method and the sine–cosine method. Bright, dark and singular solitons are revealed along with a few of the combo–soliton solutions. The existence criteria of these solitons are also given.     

Comparative study between different quantum infrared photodetectors

This paper presents a theoretical analysis for the dark current characteristics of different quantum infrared photodetectors. These quantum photodetectors are quantum dot infrared photodetectors (QDIP), quantum wire infrared photodetectors (QRIP), and quantum well infrared photodetectors (QWIP). Mathematical models describing these devices are introduced. The developed models accounts for the self-consistent potential distribution. These models are taking the effect of donor charges on the spatial distribution of the electric potential in the active region. The developed model is used to investigate the behavior of dark current with different values of performance parameters such as applied voltage, number of quantum wire (QR) layers, QD layers, lateral characteristic size, doping quantum wire density and temperature. It explains strong sensitivity of dark current to the density of QDs/QRs and the doping level of the active region. In order to confirm our models and their validity on the practical applications, a comparison between the results obtained by proposed models and that experimentally published are conducted and full agreement is observed. Several performance parameters are tuned to enhance the performance of these quantum photodetectors through the presented modeling. The resultant performance characteristics and comparison among them are presented in this work. From the obtained results we notice that the total dark current in the QRIPs can be significantly lower than that in the QWIPs. Moreover, main features of the QRIPs such as the large gap between the induced photocurrent and dark current open the way for overcoming the problems of quantum dot infrared photodetectors.     

Optimization of time-domain header processing filters using genetic algorithms

We present genetic algorithms as optimization tools for the design of header recognition filters based on time-delay lines. The fitness parameter in the selection process is the discrimination of the target against all other bit patterns. For phase-shift-keyed headers, optimized filters exhibit improved discrimination compared with the matched filter. Time-domain filtering with no ambiguities is also achieved for specific amplitude-shift-keyed headers. Delay-line-based time-domain filters can be implemented in a planar lightwave circuit platform by simple phase and amplitude adjustments on the time delay taps.     

Sonocatalytic facilitation of hydroxyl radical generation in the presence of TiO2

The generation of hydroxyl (OH) radicals was investigated during ultrasonic irradiation and in the presence of TiO(2). The effect of TiO(2) on an ultrasonic system's oxidation power was evaluated by examining the oxidation of salicylic acid. The generation of the salicylic acid derivatives, 2,3-dihydroxybenzoic acid (DHBA) and 2,5-DHBA, was measured by high-performance liquid chromatography coupled with electrochemical detection under different experimental conditions. The presence of TiO(2) enhanced the generation of DHBA during ultrasonic irradiation, thus indicating a higher oxidation power in the ultrasonic system. Al(2)O(3) also increased the generation of DHBA during irradiation; however, the effect of TiO(2) was found to be higher than that of Al(2)O(3). The addition of OH radical scavengers such as dimethylsulfoxide (DMSO), methanol and mannitol significantly suppressed the production of DHBA, and DMSO was found to have the highest suppressive effect among all scavengers. The effects of dissolved gases on the generation of OH radicals were further studied, and their power was found to be in the order Xe > Ar > O(2) > N(2). The degassing of the irradiation solution completely suppressed the generation of OH radicals. These results indicate that the presence of TiO(2) accelerates the generation of OH radicals during ultrasonic irradiation, and that the process may be mediated through the induction of cavitation bubbles in irradiating solutions.     

Zirconocene dichloride complexes with a 1,2-naphthylidene bridge as catalysts for the polymerisation of ethylene and propylene

Ansa-zirconocene dichloride complexes containing a 9-fluorenyl group at the 1-position of naphthalene and a 2-indenyl 12, 1-indenyl 13, or cyclopentadienyl 14 group at the 2-position of the naphthalene were synthesised and characterised. The molecular structures of the complexes have been determined by single crystal X-ray diffraction studies. After activation with excess methylalumoxane (MAO), the complexes were used as homogeneous catalysts for the homopolymerisation of ethylene and propylene.     

Quantitative proteomics: a review of different methodologies

The present review attempts to cover the vast array of methods which have appeared in the last few years for performing quantitative proteome analysis. These methods are divided into two classes: those applicable to conventional two-dimensional map analysis, coupling orthogonally a charge-based step (isoelectric focusing) to a size-based separation [sodium dodecylsulfate (SDS)-electrophoresis] and those applicable to two-dimensional chromatographic protocols. The first method, although being by and large the most popular approach, can offer differential display of paired samples with relatively few methods, the oldest one being based on statistical analysis performed on sets of gels via powerful software packages, such as the MELANIE, PDQuest, Z3 and Z4000, Phoretix and Progenesis. Recent developments comprise analysis performed on a single gel containing mixed samples differentially labeled, either with fluorophors (Cy3 and Cy5) or with d(0)/d(3) acrylamide. Conversely, chromatographic approaches, which mostly rely on analysis not of intact proteins but of their tryptic digests, offer a panoply of differential labeling protocols, most of which rely on stable isotope tagging. Essentially, all possible reactions have been described, such as those involving Lys, Asp, Glu, Cys residues, as well as a number of methods exploiting differential derivatization of amine and carboxyl groups generated during proteolysis. All such methods are described and evaluated.     

Extraction-spectrophotometric determination of iron(II) by ternary complex formation with pyrocatechol violet and cetyltrimethylammonium bromide

A method for iron(II) determination based on reaction with Pyrocatechol Violet to form a 1:2 binary complex at pH 5-7 is described and has been extended to an extraction-spectrophotometric procedure for the determination of iron(II) by formation of the 1:2:2 iron(II)-Pyrocatechol Violet-cetyltrimethylammonium bromide ternary complex. The molar absorptivities of the binary and ternary complexes at 595 and 605 nm are 6.55 x 10(4) and 1.35 x 10(5)1.mole(-1).cm(-1), respectively. The method has been successfully applied to the determination of iron in felspar, Portland cement and sodium hydroxide.     

Solvent effect on rate and mechanism of oxidation of chromium(III) by periodate

Summary The kinetics of chromium(III) oxidation by periodate were studied in various EtOH–H₂O solvent mixtures covering the 0.0 to 58.0 wt% EtOH range, at five different temperatures in the 15–35°C range. The rate of reaction increases with increasing EtOH content. Thermodynamic activation parameters have been calculated and an appropriate mechanism is suggested.     

Application of a Sawdust/Fe3O4 and Sawdust/Fe3O4/PEI as a Selective Adsorbent for Pb(II) Removal

Based on the advantages of Fe₃O₄ nanoparticles (MNPs), sawdust (SD), and polyethlenimine (PEI) respectively, the SD/MNPs/PEI composites with layered structure were synthesized. The features of the nanocomposites were characterized and experimental conditions were used to evaluate the potential of SD/ MNPs and SD/MNPs/PEI nanocomposites in removing lead ions Pb2+ in a batch system. By cross-linking PEI on the SD/ MNPs, chelating group on the surface of adsorbent is made, which increases the ability of the nanocomposite to attract Pb(II) from aqueous solutions. Results show an increase in the adsorption by about 31% on SD/MNPs, by about 98% in SD/MNPs/PEI.