Synthesis and Characterization of Cyclotriphosphazenes Bearing Chalcones Derivatives

A series of new cyclotriphosphazenes bearing chalcones derivatives, N₃P₃Cl₅[OC₆H₄ CH=CHC(O)C₆H₄OC_nH_2n+1] and N₃P₃[OC₆H₄CH=CHC(O)—C₆H₄OC_nH_2n+1]₆, has been synthesized. A convenient synthetic method was performed from the reaction of hexachlorocyclotriphosphazenes with one and six equivalents of (E)-3-(4-(alkyloxy)phenyl)-1-(4-hydroxyphenyl)prop-2-en-1-one (2a–c). The compounds differ in the length of alkyl groups, C_nH_2n+1, where n = 10, 12, and 14, respectively. All the products were obtained in high yields. The structures of the synthesized compounds were defined by elemental analysis, IR, ¹H, ¹³C, and ³¹P NMR.     

Giant dielectric constant and low loss tangent in polypyrrole doped with dodecylbenzene sulfonic acid

Soluble in organic solvent polypyrrole was prepared using dodecylbenzene sulfonic acid as a functional dopant. The dielectric constant was measured as high as 1.6 × 10⁴ at 100 Hz and 450 K with very low dissipation factor. This thermally activated relaxation process plays a dominant role for the low frequency dielectric response. It is suggested that this dipolar polarization may mainly originate from the hopping of charge carriers between localized sites over the potential barriers.     

New Dithiocarbamate Compounds from Organotin(IV)

Abstract

A series of new organotin(IV) dithiocarbamate compounds of type R_nSn (S₂CNR′R″)_4-n (n = 2, 3; R = dimethyl, dibutyl, diphenyl, triphenyl and tert-butyl; R′ = methyl, ethyl, benzyl; R″ = isopropyl, ethyl, ethanol) have been successfully synthesized. Elemental analysis showed that the percentage of the elements conformed to the general formula of these compounds. The important peaks of the infrared spectra for the stretching mode ν(C?N), ν(C?S), and v(Sn-S) for the compounds were observed in the area of 1440–1480 cm^?1, 940–1000 cm^?1, and 340–90 cm^?1, respectively. The ¹³C NMR spectra showed the most important peak for N¹³CS₂ chemical shifts were observed in the range 190–210 ppm. X-ray single crystal studies for several structures of these compounds showed that the chelating mode of the dithiocarbamate groups to the central tin atoms were either bidentate or anisobidentate.

GRAPHICAL ABSTRACT     

Mixed micellization of gemini surfactant with nonionic surfactant in aqueous media: a fluorometric study

Herein we report on the study of the interactions between alkanediyl-α,ω-type cationic dimeric (gemini) surfactant and the nonionic Triton X-100 in aqueous medium. The critical micelle concentrations of binary mixtures were determined by fluorometric study. Using the regular solution theory for the analysis of the experimental data, the attractive nature of interactions and synergistic behavior of gemini surfactant and Triton X-100 mixture were demonstrated. The micelle aggregation number was measured using steady state fluorescence quenching method. The micropolarity, binding constant and dielectric constant of mixed systems were determined from the ratio of peak’s intensity (I ₁/I ₃) in the pyrene fluorescence emission spectrum.     

Fabrication of Xanthan stabilized green gold nanoparticles based tolbutamide delivery system for enhanced insulin secretion in mice pancreatic islets

Abstract

Tolbutamide is an oral anti-diabetic agent for the treatment of type 2 diabetic patients. Its lower absorption results in its inferior therapeutic efficacy. Nano-carrier systems have the subject of greater interests for enhancing efficacy of such drugs. Current study was designed to improve the tolbutamide therapeutic efficacy through its delivery in Gum Xanthan (GX) stabilized green gold nanoparticles (AuNPs). GX stabilized AuNPs were characterized for surface plasmon resonance (SPR), morphology, size, polydisoersity index (PDI) and zeta potential through UV spectrophotometer, atomic force microscope (AFM) and zetasizer respectively. They were used for loading tolbutamide and loaded nanoparticles were investigated for morphology, size, PDI, zeta potential and drug loading efficiency. FT-IR analysis was used for conforming GX functional groups involvement in AuNPs stabilization and drug-excepients interactions. Tolbutamide loaded in the synthesized nanoparticles was investigated for its insulin secretion potentials in isolated mice islets. Synthesized AuNPs were found in nano-size range with spherical morphology, increased surface negativity and loaded increased concentration of drug without changing its chemical nature. They markedly enhanced the tolbutamide insulin secretion potentials as compared to simple drug solution. Results confirm that the developed nano-carrier system is highly efficient in achieving higher therapeutic efficacy of drugs like tolbutamide.     

Comparison of different mass spectrometry techniques in the measurement of L‐[ring‐13C6]phenylalanine incorporation into mixed muscle proteins

Precise measurement of low enrichment of stable isotope labeled amino‐acid tracers in tissue samples is a prerequisite in measuring tissue protein synthesis rates. The challenge of this analysis is augmented when small sample size is a critical factor. Muscle samples from human participants following an 8 h intravenous infusion of L‐[ring‐¹³C₆]phenylalanine and a bolus dose of L‐[ring‐¹³C₆]phenylalanine in a mouse were utilized. Liquid chromatography tandem mass spectrometry (LC/MS/MS), gas chromatography (GC) MS/MS and GC/MS were compared to the GC‐combustion‐isotope ratio MS (GC/C/IRMS), to measure mixed muscle protein enrichment of [ring‐¹³C₆]phenylalanine enrichment. The sample isotope enrichment ranged from 0.0091 to 0.1312 molar percent excess. As compared with GC/C/IRMS, LC/MS/MS, GC/MS/MS and GC/MS showed coefficients of determination of R² = 0.9962 and R² = 0.9942, and 0.9217 respectively. However, the precision of measurements (coefficients of variation) for intra‐assay are 13.0%, 1.7%, 6.3% and 13.5% and for inter‐assay are 9.2%, 3.2%, 10.2% and 25% for GC/C/IRMS, LC/MS/MS, GC/MS/MS and GC/MS, respectively. The muscle sample sizes required to obtain these results were 8 µg, 0.8 µg, 3 µg and 3 µg for GC/C/IRMS, LC/MS/MS, GC/MS/MS and GC/MS, respectively. We conclude that LC/MS/MS is optimally suited for precise measurements of L‐[ring‐¹³C₆]phenylalanine tracer enrichment in low abundance and in small quantity samples. Copyright © 2013 John Wiley & Sons, Ltd.     

Sand: A natural and potential catalyst in renowned Friedel Craft's acylation of aromatic compounds

The aim of this work is to develop a cheap and green chemical process and this paper describes the catalytic commotion of locally collected sand in Friedel–Craft's Acylation of aromatic compounds like benzene, anisole, aniline, naphthalene and phenol etc. The sand consists of silica and alumina as analyzed by means of EDAX and acts as a green Lewis acid. The catalyst was also characterized by using BET, SEM, and XRD techniques.     

Nanocrystalline cellulose-reinforced composite mats for lithium-ion batteries: electrochemical and thermomechanical performance

Nanocrystalline cellulose (NCC)-reinforced poly(vinylidenefluoride-co-hexafluoropropylene) (PVdF-HFP) composite mats have been prepared by electrospinning method. Polymer electrolytes formed by activating the composite mats with 1 M lithium bis(trifluoromethanesulfonyl)imide/1-butyl-3-methypyrrolidinium bis(trifluoromethanesulfonyl)imide electrolyte solution. The addition of 2 wt% NCC in PVdF-HFP improved the electrolyte retention and storage modulus of the separator by 63 and 15 %, respectively. The developed electrolyte demonstrated high value of ionic conductivity viz. 4?×?10^?4?S?cm^?1 at 30 °C. Linear scan voltammetry revealed a wide electrochemical stability of the composite mat separator up to 5 V (vs. Li⁺/Li). Cyclic voltammetry of the polymer electrolyte with a graphite electrode in 2.5 to 0 V (vs. Li⁺/Li) potential range showed a reversible intercalation/de-intercalation of Li⁺ ions in the graphite. No peaks were observed related to the reduction of the electrolyte on the anode.     

New Simulation Method to Characterize the Recoverable Component of Dynamic Negative-Bias Temperature Instability in p-Channel Metal–Oxide–Semiconductor Field-Effect Transistors

We introduce a new simulation technique to investigate the recovery characteristics of dynamic negative-bias temperature instability (NBTI) in conventional silicon dioxide (SiO₂) dielectric p-channel metal–oxide–semiconductor field-effect transistors (p-MOSFETs) based on the hydrogen diffusion and hole-trapping mechanisms. In this work, a sequence of train pulses on the gate terminal were applied to simulated p-MOSFETs in single and multiple runs, thus emulating repetitive cycles of stress and recovery. The effects of varying the applied stress voltages, temperatures, and durations were then analyzed. The recoverable component, R, of degradation was found to increase when the magnitudes of the applied stress voltage and temperature were increased. Moreover, the R was reduced when the recovery time was increased for a single run. In contrast, the R increased when the recovery time was increased for multiple runs. The normalized R of the simulated device was found to decrease by 0.7% and to increase by 7% with respect to the shortest recovery duration for a single run and for multiple runs, respectively. In addition, we measured the effects of equivalent oxide thickness (EOT) on the R and found that, in our study, the R for a transistor with a smaller EOT exhibited a substantial increase of 84% compared with that for a transistor with a larger EOT. These characteristics of the R of dynamic NBTI could be explained from the perspectives of the reaction–diffusion (R–D) model and hole-trapping mechanism. The results suggested that the underlying connection between these two mechanisms was the interface trap concentration, which represents the permanent components in both mechanisms.     

A Learning Automata-Based Solution to the Priority-Based Target Coverage Problem in Directional Sensor Networks

In recent years, directional sensor networks composed of directional sensors have attracted a great deal of attention due to their extensive applications. The main difficulties associated with directional sensors are their limited battery power and restricted sensing angle. Moreover, each target may have a different coverage quality requirement that can make the problem even more complicated. Therefore, satisfying the coverage quality requirement of all the targets in a specific area and maximizing the network lifetime, known as priority-based target coverage problem, has remained a challenge. As sensors are often densely deployed, organizing the sensor directions into several cover sets and then activating these cover sets successively is a promising solution to this problem. In this paper, we propose a learning automata-based algorithm to organize the directional sensors into several cover sets in such a way that each cover set can satisfy coverage quality requirement of all the targets. In order to verify the performance of the proposed algorithm, several simulations were conducted. The obtained results showed that the proposed algorithm was successful in extending the network lifetime.