Structural relaxation in polyethylene in the presence of silver oxide investigated by positron-lifetime spectroscopy

Structural relaxation in high-density virgin polyethylene and silver oxide doped polyethylene has been investigated using positron annihilation lifetime technique at 30 °C and 100 °C ageing temperatures. The ortho-positronium (o-Ps) pick-off lifetime and its intensity show no changes with isothermal ageing time for the virgin sample at 30 °C. In the case of the doped sample at 30 °C, the o-Ps intensity shows exponential relaxation in the short-time range. At 100 °C, the o-Ps lifetime remains almost constant, whereas the o-Ps intensity exhibits an exponential character in the virgin and doped samples, which can be fitted with exponential decay curves. The relaxation times have been evaluated from the structural relaxation function constructed using o-Ps intensity values, and the stretching exponent has been estimated using the Kohlrausch–Williams–Watts (KWW) function. Positron results indicate that the stretching exponent seems to be temperature dependent. PACS 78.70.Bj     

Synthesis of Some New 4-{2-[(Aryl)amino]-1,3-thiazol4-yl}benzene-1,2-diols as Possible Antibacterial and Antifungal Agents

Some new 4-{2-[(aryl) amino]-1,3-thiazol-4-yl}benzene-1,2-diols are prepared and characterized by spectral analysis. The newly prepared compounds are studied for their antibacterial and antifungal activity. Interestingly, almost all the compounds are found to possess promising antibacterial and antifungal activity against all tested microorganisms.     

Crystal growth,characterization and photoluminescence study of a novel one dimensional coordination polymer of Cd(II) with thiophene-2,5-dicarboxylic acid

A novel one dimensional coordination polymer of Cd(II) with thiophene-2,5-dicarboxylic acid (H₂tdc), {[Cd(tdc) (H₂O)₃]·1.5H₂O}_n has been prepared by gel diffusion method. Elemental analysis, single crystal and powder X-ray diffraction studies, FT-IR and UV–visible spectral studies were used to characterize the title compound. Cd-thiophene units form a linear chain in the crystal structure. Thiophene rings of a linear chain are stacked parallel to each other while the thiophene rings of the adjacent chains are intercalated and stacked ant-parallel to each other. Extensive hydrogen bond formation and π-π interactions between thiophene moieties are responsible for the supramolecular architecture. TG/DTG studies confirm the presence of both lattice and coordinated water molecules. Photoluminescence studies showed that the title compound is red shifted by 46 nm compared to ligand.     

Untargeted Metabolomic Approach to Determine the Regulatory Pathways on Salicylic Acid-Mediated Stress Response in Aphanamixis polystachya Seedlings

Plants thrive under abiotic and biotic stress conditions with the changes in phytohormones like salicylic acid (SA), resulting in the synthesis of secondary metabolites. The present study determines the response of plants in producing secondary metabolites towards different SA concentrations at varying time intervals. Liquid chromatography-mass spectrometry-based metabolomics studies in Aphanamixis polystachya (Wall.) Parker seedlings are grown at 10 mM, 50 mM, and 100 mM SA concentrations, showed the differential expression of metabolites towards the stress. Alkaloids like amaranthin showed a 15-fold increase on the second day, and analog of androvinblastin showed a 20-fold increase on the sixth day in 10 mM SA compared with other groups. Flavanoid cyanidin 3-3 glucosyl was found to be with a 22-fold increment along with terpenoids betavulgaroside (18-fold), asiaticoside (17-fold), mubenin B (20-fold), and deslanoside (22-fold) increment in 50 mM SA on the sixth day. The shock exerted by 100 mM was too harsh, and the lowered metabolite production level was insufficient for the seedlings to survive at this higher SA condition. Arrangement of stressed groups using Pearson correlation studies, principal component analysis, and partial least square analysis placed 10 mM SA and controlled group closer and 50 mM SA and 100 mM SA groups closer to each other. The study observed that SA regulates metabolites that mediate biotic stress responses at low concentrations, and higher concentrations regulate abiotic stress regulating metabolites.     

Total Synthesis of (−)‐Cleistenolide

An efficient and short total synthesis of (?)‐cleistenolide ( 1 ) from D ‐mannitol with an overall yield of 23.6% is described. The chiron approach for the synthesis of (?)‐cleistenolide involves a one‐C‐atom Wittig olefination, a selective allylic triethylsilyl protection, and a Grubbs‐catalyzed ring‐closure‐metathesis (RCM) reaction as the key steps.     

Synthesis and Characterization of Some Novel 3-Bromo-2-acetylthiophene Chalcones and Biological Evaluation of Their Ethyl-4-(3-bromothien-2-yl)-2-oxo-6-(aryl)cyclohex-3-ene-1-carboxylate Derivatives

Novel chalcones 1-(3-bromothien-2-yl)-3-(aryl)prop-2-en-1-ones derived from 3-bromo-2-acetylthiophene and their cyclization product with ethylacetoacetate such as 4-(3-bromothien-2-yl)-2-oxo-6-(aryl)cyclohex-3-ene-1-carboxylate derivatives were synthesized and studied by X-ray, analytical, and spectral methods. Compounds were screened for their anti-inflammatory, analgesic, and antimicrobial activities. The compound ethyl-4-(3-bromothien-2-yl)-2-oxo-6-(4-propoxyphenyl) cyclohex-3-ene-1-carboxylate 5c exhibited promising anti-inflammatory, analgesic and antibacterial activities.