Electronic structure of (BP)n/(BAs)n (0 0 1) superlattices

An accurate ab initio full potential linear muffin-tin orbital method has been used to investigate the structural, electronic and optical properties of BP, BAs and their (BP)_n/(BAs)_n superlattices (SLs). The exchange-correlation potential is treated with the local density approximation of Perdew and Wang (LDA-PW). The calculated structural properties of BP and BAs compounds are in good agreement with available experimental and theoretical data. It is found that BP, BAs and their alloys exhibit an indirect fundamental band gap. The fundamental band gap decreases with increasing the number of monolayer n. The optical properties show that the static dielectric constant significantly decreases in superlattices compared to their binary compounds.     

Synthesis, spectral, thermal and antimicrobial studies of some new tri metallic biologically active ceftriaxone complexes

Iron, cobalt, nickel and copper complexes of ceftriaxone were prepared in 1:3 ligand:metal ratio to examine the ligating properties of the different moieties of the drug. The complexes were found to have high percentages of coordinated water molecules. The modes of bonding were discussed depending on the infrared spectral absorption peaks of the different allowed vibrations. The Nujol mull electronic absorption spectra and the magnetic moment values indicated the Oh geometry of the metal ions in the complexes. The ESR spectra of the iron, cobalt, and copper complexes were determined and discussed. The thermal behaviors of the complexes were studied by TG and DTA techniques. The antimicrobial activities of the complexes were examined and compared to that of the ceftriaxone itself.     

Design,synthesis and molecular docking of new [1,2,4] triazolo[4,3-a]quinoxaline derivatives as anticancer agents targeting VEGFR-2 kinase

Molecular Diversity - Vascular endothelial growth factor receptor-2 (VEGFR-2) is critically involved in cancer angiogenesis. Blocking of VEGFR-2 signaling pathway proved effective suppression of...     

Second Derivative Spectrophotometric Determination of the Binding Constant Between Codeine Phosphate and Bovine Serum Albumin

Second derivative spectrophotometry was applied to determine the binding constant (K) between codeine phosphate (COD) and bovine serum albumin (BSA) at simulated physiological conditions (37.00?°C and pH = 7.4). The second derivative spectra of COD in buffer solutions containing various amounts of BSA showed derivative isosbestic points. The residual background signals derived from incomplete suppression of BSA signals can be entirely eliminated in the second derivative spectra indicating that BSA has spectrophotometrically one kind of binding site for COD. The fractions of COD bound to BSA were calculated from the derivative intensity differences (??D values) of COD before and after the addition of BSA. Scatchard plot calculation suggested that the binding of COD to BSA can be explained by a partition-like non-specific binding model. The binding constant (K) was calculated from ??D values according to the non-specific binding model by a nonlinear least-squares method. K values were almost constant for all of the COD concentrations studied with good reproducibility. The fractions predicted by the K values were in good agreement with the observed values. The results indicate the usefulness of the derivative method in drug?Calbumin binding studies without the need for prior separation procedures which may disturb the equilibrium states of the samples solutions.     

Molluscicidal activity of methomyl and cardenolide extracts from Calotropis procera and Adenium arabicum against the land snail Monacha cantiana

In this work, we have evaluated the molluscicidal activity of two cardenolide extracts from Adenium arabicum Balf f. [the benzene (B) and methanol (M) extracts], one cardenolide extract from Calotropis procera (Aiton) W.T. Aiton (extract C), and methomyl against the harmful land snail Monacha cantiana (Montagu). The contact LD?? values for the above mentioned plant extracts were 12.62, 34.63, and 34.35 mg·kg?1 of body weight, respectively, while the LD?? for methomyl was 116.62 mg·kg?1, that is, the plant extracts were 9.24, 3.37, and 3.4 times more toxic than methomyl. In addition, a simple colorimetric method, based on Kedde reagent, was modified to determine cardenolide concentrations in plant extracts. Thin layer chromatography analysis (TLC) showed several cardiac glycosidal compounds in each plant extract. The results proved that cardiac glycosides are promising candidate compounds that could be used to control land snails, or exploited to develop new, effective, and environmentally friendly molluscicides.     

Extractive-spectrophotometric methods for determination of anti-Parkinsonian drug in pharmaceutical formulations and in biological samples using sulphonphthalein acid dyes

A simple, accurate and highly sensitive spectrophotometric methods are proposed for the rapid and accurate determination of amantadine HCl (AMD) using bromocressol green (BCG), bromophenol blue (BPB) and bromothymol blue (BTB). The developed methods involve formation of stable yellow colored chloroform extractable ion-associate complexes of the amino derivative (basic nitrogen) of the AMD with three sulphonphthalein acid dyes, namely; BCG, BPB and BTB, in acidic medium. The ion-associates exhibit absorption maxima at 415, 412 and 414 nm for BCG, BPB and BTB, respectively. AMD can be determined up to 1.5–16.5, 1.4–14.0 and 1.6–17 μg mL^?1, respectively. The effect of optimum conditions via acidity, reagent concentration, time, and solvent was studied. The stoichiometry of the reaction was found to be 1:1 in all cases. The low relative standard deviation values indicate good precision and high recovery values. These methods have been successfully applied for the assay of AMD in pharmaceutical formulations. Statistical comparison of the results with the reference method shows excellent agreement and indicates no significant difference in accuracy and precision.     

Surface and Bulk Structure of Thin Spin Coated and Plasma-Polymerized Polystyrene Films

Polystyrene (PS) spin coated thin films were modified by O₂ and Ar plasma as well as by UV irradiation treatments. The modified PS samples were compared with plasma polymerized and commercial polystyrene. The effects of plasma (O₂ and Ar) and UV irradiation treatments on the surface and the bulk properties of the polymer layers were discussed. The surface properties were evaluated by X-ray Photoelectron Spectroscopy and Contact angle measurements and the bulk properties were investigated by FTIR and dielectric relaxation spectroscopy. As a result only one second treatment time was sufficient to modify the surface. However, this study was also dedicated to understand the effect of plasma and plasma irradiation on the deposited layers of plasma polymers. The dielectric measurements showed that the plasma deposited films were not thermally stable and underwent an undesired post-plasma chemical oxidation.     

Spectroscopic studies on some azo compounds and their cobalt, copper and nickel complexes

Synthesis and characterization of [o-carboxy phenylazo] moiety of barbituric acid, thiobarbituric acid, thiouracil, citrazinic acid, and disodium chromotropate and their complexes derived from cobalt (II), nickel (II), and copper (II) salts were done. The stereochemistry and the mode of bonding of the complexes were achieved based on elemental analysis, NMR, UV-Vis, IR and ESR. The dissociation constants of the free azo ligands are evaluated by spectrophotometric methods.     

Composition,microstructure, Vickers hardness and activation energies of Co–Cu alloys fabricated by arc melting technique

We have determined the phase transition for the Co-20 and -30 at.% Cu alloys fabricated by arc melting technique, from the binodal to the two phases α?+?L as well as the peritectic transitions, using differential thermal analysis (DTA). We equally studied the effects of aging treatment, ranging from 3 to 35?h, on the alloy samples using scanning electron microscopy (SEM) and Vickers hardness (HV). The activation energies of these alloys are equally determined using five established models. Our results show that for aging time up to 15?h, within the spinodal region at 773?K, the hardness value for Co-20 and -30 at.% Cu alloys oscillates reaching a local maximum at the aging time of 8.5?±?0.5?h. After 20?h of heat treatment, the HV for Co-20 at.% Cu alloy diminishes significantly while that of Co-30 at.% Cu effectively stabilizes at 241?MPa. The activation energies for the peritectic transformation based on Ozawa model are estimated to be 2465 and 2680?kJ?mol^?1 for Co-20 and -30 at.% Cu, respectively.     

Cloud-Point Extraction and Spectrophotometric Determination of Trace Quantities of Bismuth in Environmental Water and Biological Samples

ABSTRACT

A cloud-point extraction (CPE) process using the nonionic surfactant Triton X-114 to extract bismuth from aqueous solutions was investigated. The method is based on the complexation reaction of Bi(III) with 4-(2-benzothiazolylazo)2,2′-biphenyldiol (BTABD) and micelle-mediated extraction of the complex. The optimal extraction and reaction conditions (e.g., pH, reagent concentration, surfactant concentration, and effect of time) were studied. The analytical characteristics of the method (e.g., linear range, molar absorptivity, Sandell sensitivity, optimum Ringbom concentration ranges, limits of detection and quantification, preconcentration factor, and improvement factors) were obtained. Linearity was obeyed in the range of 2.50–85.0 ng mL^?1 of Bi(III) ion. The detection limit of the method was 0.75 ng mL^?1 of Bi(III) ion. The interference effect of some anions and cations was also tested. The method was applied to the determination of bismuth in environmental water, human hair, and urine samples.