A new method for determining the local environment and orientation of individual side chains of membrane-binding peptides

We studied here the binding of the mastoparan X peptide to a zwitterionic lipid bilayer (POPC) and demonstrated that nitrile-derivatized amino acids can be used to determine the hydration state (or change in hydration state) of specific sites of membrane-interactive peptides (upon binding). We have also shown that polarized ATR-FTIR measurements can further be used to uncover information regarding the spatial orientation of individual side chains as well as their conformational preference within the lipid bilayer.     

Quantitative Characterization of Bovine Serum Albumin, α-Lactalbumin and β-Lactoglobulin in Commercial Whey Sample by RP-LC

A simple, sensitive and precise reverse phase liquid chromatographic method has been developed and validated for quantification of bovine serum albumin (BSA), α-lactalbumin (α-La) and β–lactoglobulin (β-Lg) that are removed from whey waste by foam fractionation method. The data is reproducible over a wide concentration range. This optimized method allowed analysis of BSA, α-La, β-Lg in a mixture within 5 min and could be applied to the analysis of a variety of commercial and laboratory whey products within a short time.     

Thermal‐initiating potentialities of vinyl polyperoxides: Transmutation of block‐into‐block copolymer and an exploratory investigation of surface texture and morphology

This article describes the first comprehensive study on the use of vinyl polyperoxides, namely, poly(α‐methyl styrene peroxide) (PMSP) and poly(styrene peroxide) (PSP), as thermal initiators for the synthesis of active polymers, PMSP–PS–PMSP/PSP–PS–PSP, by free‐radical polymerization with styrene. The active polymers have been characterized by ¹H NMR, differential scanning calorimetry, thermogravimetric analysis, and gel permeation chromatography analysis. The PMSP–PS–PMSP/PSP–PS–PSP is further used as the thermal macroinitiator for the preparation of another block copolymer, PS‐b‐PMMA, through the reaction of the active polymers with methyl methacrylate. The mechanism of the block copolymer formation is discussed. Having established the scanning micrograph details of the homopolymer phases, we analyze the surface features and morphology of the block copolymer. Furthermore, the distinction in appearance is highlighted with a view toward strengthening the chemistry with the structural appearance in materials processed differently. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 3665–3673, 2000     

Influence of sputter power on structural and electrical properties of TiO2 films for Al/TiO2/Si gate capacitors

Titanium dioxide (TiO₂) thin films were deposited onto p‐Si substrates held at room temperature by reactive Direct Current (DC) magnetron sputtering at various sputter powers in the range 80–200 W. The as‐deposited TiO₂ films were annealed at a temperature of 1023 K. The post‐annealed films were characterized for crystallographic structure, chemical binding configuration, surface morphology and optical absorption. The electrical and dielectric properties of Al/TiO₂/p‐Si structure were determined from the capacitance–voltage and current–voltage characteristics. X‐ray diffraction studies confirmed that the as‐deposited films were amorphous in nature. After post‐annealing at 1023 K, the films formed at lower powers exhibited anatase phase, where as those deposited at sputter powers > 160 W showed the mixed anatase and rutile phases of TiO₂. The surface morphology of the films varied significantly with the increase of sputter power. The electrical and dielectric properties on the air‐annealed Al/TiO₂/p‐Si structures were studied. The effect of sputter power on the electrical and dielectric characteristics of the structure of Al/TiO₂/p‐Si (metal‐insulator‐semiconductor) was systematically investigated. Copyright © 2014 John Wiley & Sons, Ltd.     

Enhanced photocatalytic and adsorptive degradation of organic dyes by mesoporous Cu/Al2O3-MCM-41: intra-particle mesoporosity, electron transfer and OH radical generation under visible light

Mesoporous Cu/Al(2)O(3)-MCM-41 composite was synthesized by two step processes; in situ incorporation of high surface area mesoporous Al(2)O(3) (MA) into the framework of MCM-41 (in situ method) followed by impregnation of Cu(II) by incipient wetness method. The interesting thing is that starch was used for the first time as template for the preparation of high surface area MA. To evaluate the structural and electronic properties, these catalysts were characterized by low angle X-ray diffraction (LXRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), UV-vis DRS, FTIR and photoluminescent (PL) spectra. The various cationic dye such as methylene blue (MB), methyl violet (MV), malachite green (MG) and rhodamine 6G (Rd 6G) of high concentration 500 mg L(-1) were degraded and adsorbed very efficiently (100%) using the 5 Cu/Al(2)O(3)-MCM-41 composite within 30 and 60 min, respectively. The high and quick removal of such concerted cationic organic dyes and also mixed dyes (MB+MV+MG+Rd 6G) by means of photocatalysis/adsorption is basically due to the combined effect three characteristics of synthesized mesoporous 5 Cu/Al(2)O(3)-MCM-41 composite. These characteristics are intra-particle mesoporosity, electron transfer and ˙OH radical generation under solar light.     

Pyrene-containing peptide-based fluorescent organogels: inclusion of graphene into the organogel

The N-terminally pyrene-conjugated oligopeptide, Py-Phe-Phe-Ala-OMe, (Py=pyrene 1-butyryl acyl) forms transparent, stable, supramolecular fluorescent organogels in various organic solvents. One of these organogels was thoroughly studied using various techniques including transmission electron microscopy (TEM), field-emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), Fourier-transform infrared (FTIR) spectroscopy, photoluminescence (PL) spectroscopy, and rheology. Unfunctionalized and non-oxidized graphene was successfully incorporated into this fluorescent organogel in o-dichlorobenzene (ODCB) to form a stable hybrid organogel. Graphene is well dispersed into the gel medium by using non-covalent π-π stacking interactions with the pyrene-conjugated gelator peptide. In the presence of graphene, the minimum gelation concentration (mgc) of the hybrid organogel was lowered significantly. This suggests that there is a favorable interaction between the graphene and the gelator peptide within the hybrid organogel system. This hybrid organogel was characterized using TEM, AFM, FTIR, PL, and rheological studies. The TEM study of graphene-containing hybrid organogel revealed the presence of both graphene sheets and entangled gel nanofibers. The AFM study indicated the presence of 3 to 4 layers in exfoliated graphene in ODCB and the presence of both graphene nanosheets and the network of gel nanofibers in the hybrid gel system. The rheological investigation suggested that the flow of the hybrid organogel had become more resistant towards the applied angular frequency upon the incorporation of graphene into the organogel. The hybrid gel is about seven times more rigid than that of the native gel.     

Polymerization of Methyl Methacrylate: Kinetics of the Reaction Initiated by the Mn(III)-1,2-Propanediol Redox System

Kinetics of polymerization of methyl methacrylate initiated by Mn³⁺/1,2-propanedlol has been investigated in aqueous sulfuric acid at the temperature range of 25–35°C. The rate of polymerization (R_p) and the rate of manganic ion disappearance (-R_Mn) have been computed. The effects of organic solvents, certain cationic and anionic detergents, added electrolytes on the initial rate of polymerization, and maximum conversion have been examined. Depending on the kinetic results, a reaction scheme has been suggested involving the formation of a complex between Mn³⁺ and the alcohol, which subsequently decomposed in an unimolecular step to generate the initiating free-radical which initiates polymerization and termination of the growing polymer chain by metal ion.     

Synthesis,Crystal Structure,and Electrochemical Properties of a Simple Magnesium Electrolyte for Magnesium/Sulfur Batteries

Most simple magnesium salts tend to passivate the Mg metal surface too quickly to function as electrolytes for Mg batteries. In the present work, an electroactive salt [Mg(THF)₆][AlCl₄]₂ was synthesized and structurally characterized. The Mg electrolyte based on this simple mononuclear salt showed a high Mg cycling efficiency, good anodic stability (2.5 V vs. Mg), and high ionic conductivity (8.5 mS cm^?1). Magnesium/sulfur cells employing the as‐prepared electrolyte exhibited good cycling performance over 20 cycles in the range of 0.3–2.6 V, thus indicating an electrochemically reversible conversion of S to MgS without severe passivation of the Mg metal electrode surface.     

De novo design of a redox-active minimal rubredoxin mimic

Metal-binding sites in metalloproteins frequently occur at the interfaces of elements of secondary structure, which has enabled the retrostructural analysis of natural proteins and the de novo design of helical bundles that bind metal ion cofactors. However, the design of metalloproteins containing beta-structure is less well developed, despite the frequent occurrence of beta-conformations in natural metalloproteins. Here, we describe the design and construction of a beta-protein, RM1, that forms a stable, redox-active 4-Cys thiolate Fe(II/III) site analogous to the active site of rubredoxin. The protein folds into a beta-structure in the presence and absence of metal ions and binds Fe(II/III) to form a redox-active site that is stable to repeated cycles of oxidation and reduction, even in an aerobic environment.     

An existence theorem of Walrasian equilibrium

The purpose of this note is to establish an existence theorem for Walrasian equilibrium under weaker conditions.