Vitamin D(2) modulates melittin-membrane interactions

In the present work, mutual interaction of melittin, a pore forming hemolytic toxin from bee venom, and vitamin D(2), an antioxidant steroid, with dipalmitoyl phosphatidylcholine (DPPC) multilamellar liposomes has been investigated. Turbidity and Fourier transform infrared (FTIR) spectroscopic measurements, in combination with thermodynamic calculations, were used to monitor the modulating effect of vitamin D(2) on a melittin-DPPC membrane system. The results indicate that melittin on its own decreases the main phase transition to lower temperatures and also dramatically decreases the stability of the membrane. It has an overall disordering effect on the phospholipid membrane structures. Inclusion of vitamin D(2) at low concentrations (3, 6 mol%) into melittin containing DPPC liposomes slightly shifts the main phase transition to lower temperatures. High concentration of vitamin D(2) (9 mol%) has a more dramatic effect in shifting the main phase transition to lower temperature. It also causes a significant broadening in the phase transition curve. The present study also demonstrates that, with the addition of vitamin D(2) into melittin-DPPC system, absorbance value in turbidity study and the frequency of the CH(2) stretching band in FTIR study changes in a manner that are consistent with a reduction in the membrane perturbing effect of melittin on DPPC liposomes. Vitamin D(2) diminishes the disordering effect of melittin on DPPC lipids and produces a more ordered membrane system. These results were confirmed with thermodynamic calculations.     

Robust sampled‐data control of uncertain switched neutral systems with probabilistic input delay

This article focuses on the robust sampled‐data control for a class of uncertain switched neutral systems based on the average dwell‐time approach. In particular, the system is considered with probabilistic input delay using sampled state vectors, which are described by the stochastic variables with a Bernoulli distributed white sequence and time‐varying norm‐bounded uncertainties. By constructing a novel Lyapunov–Krasovskii functional which involves the lower and upper bounds of the delay, a new set of sufficient conditions are derived in terms of linear matrix inequalities for ensuring the robust exponential stability of the uncertain switched neutral system about its equilibrium point. Moreover, based on the stability criteria, a state feedback sampled‐data control law is designed for the considered system. Finally, a numerical example based on the water‐quality dynamic model for the Nile River is given to illustrate the effectiveness of the proposed design technique. © 2015 Wiley Periodicals, Inc. Complexity 21: 308–318, 2016     

Generation of onions and nanotubes of GaS and GaSe through laser and thermally induced exfoliation

Although theoretical calculations have predicted that layered GaS and GaSe should form nanotube and related structures, they have not been prepared experimentally to date. We have carried out laser irradiation as well as thermal treatment of GaS and GaSe to cause exfoliation, which yielded onionlike structures and nanotubes by the rolling of the exfoliated sheets.     

An exact solution for static scalar fields coupled to gravity in (2+1)-dimensions

We obtain an exact solution for the Einstein’s equations with cosmological constant coupled to a scalar, static particle in static, “spherically” symmetric background in (2+1)-dimensions.     

Synthesis, structural and conductivity characterization of alginic acid–Fe3O4 nanocomposite

Alginic acid–Fe₃O₄ nanocomposite is synthesized by the precipitation of Fe₃O₄ in the presence of alginic acid (AA). Structural, surface, morphological, thermal and electrical transport properties of the nanocomposite were performed by XRD, FT-IR, TEM-SEM, TGA and conductivity measurements respectively. FT-IR analysis revealed that Fe₃O₄ NPs are strongly capped with AA and TGA analysis showed that nanocomposite have 80% of Fe₃O₄ content. TEM analysis of Fe₃O₄ NPs show an average particle size of 9.5 nm, and upon nanocomposite formation with AA these particles are observed to form aggregates of ~150 nm. The frequency-dependency of the AC conductivity show electrode polarization effect. Analysis of electrical modulus and dielectric permittivity functions suggest that ionic and polymer segmental motions are strongly coupled. DC electrical conductivity is strongly temperature dependent, and is classified into three regions over a limited temperature range of up to 100 °C.     

A conjoined thienopyrrole oligomer formed by using DNA as a molecular guide

A thienopyrrole oligomer conjoined to DNA was prepared by means of a templated synthesis protocol. The oligomer was formed by reaction, initiated with HRP/H2O2, of thieno[3,2-b]pyrrole monomers attached to cytosine bases. The thienopyrrole oligomer was characterized spectroscopically.     

Dye removal by a novel hydrogel‐clay nanocomposite with enhanced swelling properties

Acrylamide (AAm)‐2‐acrylamide‐2‐methylpropanesulfonic acid sodium salt (AMPSNa) hydrogel and AAm‐AMPSNa/clay hydrogel nanocomposite having 10 w% clay was prepared by in situ copolymerization in aqueous solution in the presence of a crosslinking agent (N,N′‐methylenebisacrylamide (NMBA)). Swelling properties and kinetics of the hydrogel samples were investigated in water and aqueous solutions of the Safranine‐T (ST) and Brilliant Cresyl Blue (BCB) dyes. The swelling and diffusion parameters were also calculated in water and dye solutions. It was observed that the AAm‐AMPSNa/clay hydrogel nanocomposite exhibits improved swelling capacity compared with the AAm‐AMPSNa hydrogel. It was also found that the diffusion mechanisms show non‐Fickian character. Adsorption properties of the hydrogel samples in the aqueous solution of ST and BCB dyes were also investigated. Clay incorporation into the hydrogel structure increased not only the adsorption capacity but also the adsorption rate. Adsorption capacity values of the hydrogel nanocomposite were found to be 484.2 and 494.2 mg g^?1 for the ST and BCB dyes, respectively. It was seen that the adsorption of dyes by the hydrogel nanocomposite completed in 10 min while the AAm‐AMPSNa hydrogel adsorbed dyes approximately in 90 min. Adsorption data of the samples were modelled by the pseudo‐first‐order and pseudo‐second‐order kinetic equations in order to investigate dye adsorption mechanism. It was found that the adsorption kinetics of hydrogel nanocomposite followed a pseudo‐second‐order model. Equilibrium isotherms were analyzed using the Langmuir and Freundlich isotherms. It was seen that the Langmuir model fits the adsorption data better than the Freundlich model. Copyright © 2008 John Wiley & Sons, Ltd.     

Analysis of Cosmogenic Neutron Characteristics and the Pulses Counting Rate Using ASD,LSD, and LVD Scintillation Detectors

Journal of Experimental and Theoretical Physics - Experimental data obtained using three scintillation detectors are analyzed. The characteristics of cosmogenic neutrons in underground experiments...     

Analysis of 2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine and Its Phase I and Phase II Metabolites in Mouse Urine Using LC�CUV�CMS�CMS

2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) is an abundantly present heterocyclic aromatic amine which is found to be carcinogenic in rodents, mice and rats. The biotransformation of PhIP is extensive and involves both the formation of bioactivated as well as detoxification metabolites. In order to understand its carcinogenicity, the metabolism of PhIP needs to be studied. Numerous metabolites of PhIP have been described but, so far, assays for their quantitative determination in biological matrices are scarce. We present the development and application of an assay, using reversed phase liquid chromatography coupled to ultraviolet and mass spectrometry detectors for the quantification of PhIP, three phase I and nine phase II metabolites in urine. Additionally, the identification of two PhIP-sulfates by the use of NMR is presented. Sample pretreatment consisted of straightforward dilution of urine. PhIP and its metabolites were shown to be stable in diluted urine for at least 22 h when stored at 2?C8 °C. Precision of the analysis was within 15%. The assay has been successfully applied for the quantification of PhIP and 12 of its metabolites in urine from mice that received 200 mg kg^?1 PhIP via oral gavage.