Structuring in aqueous solutions of polydiphenylenesulfophthalide: dimensions of associates and their local mobility

The dimensions of associates formed in aqueous solutions of polydiphenylenesulfophthalide (PDPSP) and products of its treatment with alkali-metal hydroxides are measured by light scattering. As shown by EPR spin-probe spectroscopy, the associates are hydrophobic structures. The local mobility of polydiphenylenesulfophthalide associates is lower than that of associates of the polymer treated with alkalimetal hydroxides, but, in all cases, this value is commensurable with the local mobility of solid polystyrene.     

Electrochemical chlorine-free AC disinfection of water contaminated with <Emphasis Type="Italic">Salmonella typhimurium</Emphasis> bacteria

Deionized (DI) water contaminated with Salmonella typhimurium (S. typhimurium) bacteria was disinfected by alternating current. Ammonium sulfate was used as electrolyte. Disinfection was carried out in the circulation system including an electrochemical cell with stainless steel electrodes. The process efficiency was estimated and the number of killed bacteria was directly proportional to the water treatment time and concentration of hydroxyl radicals generated by electrolysis. The presence of OH radicals was detected with N,N-dimethyl-p-nitrosoaniline (RNO) used as a spin trap. Similar experiments were carried out with water remaining after poultry washing at poultry farms and additionally contaminated with S. typhimurium bacteria. Measures were recommended to increase the process efficiency and decrease the water treatment time.     

Noncovalent Hydrogen Isotope Effects in Paramagnetic Molecules

Zero-point energies (ZPE) of intermolecular, non-bonded vibrations and isotope effects, induced by noncovalent interactions, are computed for paramagnetic molecules. They appear to be not significant for complexation of HO₂ and oxygen with C–H bonds and results to isotope effect, which deviates from unit by 5–10%. However, ZPE and isotope effects in complexes of HO₂ and nitroxyl radicals with water are larger and reach 50–70%. The largest effect, about 12, is found for complexation of hydrogen atom with water. Complexation of nitroxyl and peroxy radicals by hydrogen bonds is accompanied by transfer of spin density of unpaired electron from radical to the ligand molecules and induces high field paramagnetic shifts of the ligand NMR lines. It evidences that the spin transfer via intermolecular bonds occurs by mechanism of spin polarization.     

Molecular mobility of spin-labelled terephthaloyl chloride and 1,10-decanediol copolymer in solution

Intramolecular mobility of spin-labelled terephthaloyl chloride and 1,10-decanediol copolymer in solution was investigated using a polymer in which the label was rigidly attached to the main chain methylene groups. Correlation times and effective segmental dimensions were measured, as were the frequency and amplitude of the high-frequency torsional vibrations of the main chain monomer units. The amplitude of high-frequency torsional vibrations was shown to increase with increasing temperature.     

Rational Design of Plant Hairpin-like Peptide EcAMP1: Structural–Functional Correlations to Reveal Antibacterial and Antifungal Activity

Plant antimicrobial peptides from the α-hairpinins family (hairpin-like peptides) are known to possess a wide range of biological activities. However, less is known about the structural determinants of their antimicrobial activity. Here, we suggest that spatial structure as well as surface charge and hydrophobicity level contribute to the antimicrobial properties of α-hairpinin EcAMP1 from barnyard grass (Echinochloa cruss-galli) seeds. To examine the role of the peptide spatial structure, two truncated forms of EcAMP1 restricted by inner and outer cysteine pairs were synthesized. It was shown that both truncated forms of EcAMP1 lost their antibacterial activity. In addition, their antifungal activity became weaker. To review the contribution of surface charge and hydrophobicity, another two peptides were designed. One of them carried single amino acid substitution from tryptophan to alanine residue at the 20th position. The second one represented a truncated form of the native EcAMP1 lacking six C-terminal residues. But the α-helix was kept intact. It was shown that the antifungal activity of both modified peptides weakened. Thereby we can conclude that the secondary structural integrity, hydrophobic properties, and surface charge all play roles in the antimicrobial properties of α-hairpinins. In addition, the antibacterial activity of cereal α-hairpinins against Gram-positive bacteria was described for the first time. This study expands on the knowledge of structure–function interactions in antimicrobial α-hairpinins.     

Metal-Glass-Ceramic Phases on the Surface of Porous TiNi-Based SHS-Material for Carriers of Cells

Russian Physics Journal - Using the methods of SEM, EDS, and optical microscopy, a large number of non-metallic inclusions are revealed on the pore surface of a TiNi-based SHS-alloy. According to...