University of Madras

About: University of Madras is a education organization based out in Chennai, Tamil Nadu, India. It is known for research contribution in the topics: Ring (chemistry) & Lipid peroxidation. The organization has 8496 authors who have published 11369 publications receiving 211152 citations. The organization is also known as: Madras University & University of Chennai.

Nanostructured Bi(1−x)Gd(x)FeO3 – a multiferroic photocatalyst on its sunlight driven photocatalytic activity

Abstract: The photocatalytic activity of sol–gel synthesized nanostructured Bi1−xGdxFeO3 (x = 0, 0.05, 0.1, 0.15) particles on the degradation of methylene blue (MB) was demonstrated for the first time under sunlight. The X-ray diffraction (XRD) studies showed that the substitution induced structural changes in 10 and 15% Gd substituted BiFeO3 (BFO). The morphology analysis, by field emission scanning (FESEM) and high resolution transmission electron microscopy (HRTEM), presented the composition driven particle size reduction and morphology changes in BFO from irregular to spherical shape. The band gap estimation by UV-visible diffuse reflectance spectroscopy revealed that increasing concentration of Gd significantly reduced the band gap of BFO from 2.38 eV to 2.29 eV. An anomalous magnetic enhancement was observed in Bi0.90Gd0.10FeO3 nanoparticles due to the manifestation of antiferromagnetic (AFM) core–ferromagnetic (FM) shell-like structure, revealed by its M–H hysteresis curve. An increasing trend in the photocatalytic activity of BFO was observed with increasing concentration of Gd. In this case, enhanced photocatalytic activity observed in Bi0.85Gd0.15FeO3 could be due to its increased ferroelectric domains that drive the charge carriers to the catalyst surface–dye interface, leading to more effective degradation of the dye. Conversely, an anomalous photocatalytic activity was observed in Bi0.90Gd0.10FeO3 that should be attributed to its AFM–FM core–shell-like structure.

Genotoxicity evaluation of heat shock in gold fish (Carassius auratus)

Abstract: Genotoxicity evaluation of heat shock was carried out in Carassius auratus. The genotoxicity end points studied were nuclear anomalies (micronucleus assay), chromosomal aberrations, DNA damage (comet assay) and cell proliferation. The heat shock temperatures used were 34°C, 36°C and 38°C. The results demonstrated that heat shock causes the induction of micronucleus at all the three temperature studied. Heat shock also inhibited cell proliferation at 38°C and caused aberrations in the metaphase chromosomes at 34°C and 36°C. Comet assay demonstrated single strand DNA damage at all the three temperatures. The results obtained indicate that heat shock is a genotoxicant.

Distribution and Relationships of Antimicrobial Resistance Determinants among Extended-Spectrum-Cephalosporin-Resistant or Carbapenem-Resistant Escherichia coli Isolates from Rivers and Sewage Treatment Plants in India.

Abstract: To determine the distribution and relationship of antimicrobial resistance determinants among extended-spectrum-cephalosporin (ESC)-resistant or carbapenem-resistant Escherichia coli isolates from the aquatic environment in India, water samples were collected from rivers or sewage treatment plants in five Indian states. A total of 446 E. coli isolates were randomly obtained. Resistance to ESC and/or carbapenem was observed in 169 (37.9%) E. coli isolates, which were further analyzed. These isolates showed resistance to numerous antimicrobials; more than half of the isolates exhibited resistance to eight or more antimicrobials. The blaNDM gene was detected in 14/21 carbapenem-resistant E. coli isolates: blaNDM-1 in 2 isolates, blaNDM-5 in 7 isolates, and blaNDM-7 in 5 isolates. The blaCTX-M gene was detected in 112 isolates (66.3%): blaCTX-M-15 in 108 isolates and blaCTX-M-55 in 4 isolates. We extracted 49 plasmids from selected isolates, and their whole-genome sequences were determined. Fifty resistance genes were detected, and 11 different combinations of replicon types were observed among the 49 plasmids. The network analysis results suggested that the plasmids sharing replicon types tended to form a community, which is based on the predicted gene similarity among the plasmids. Four communities each containing from 4 to 17 plasmids were observed. Three of the four communities contained plasmids detected in different Indian states, suggesting that the interstate dissemination of ancestor plasmids has already occurred. Comparison of the DNA sequences of the blaNDM-positive plasmids detected in this study with known sequences of related plasmids suggested that various mutation events facilitated the evolution of the plasmids and that plasmids with similar genetic backgrounds have widely disseminated in India.

Di- and Tetranuclear Ruthenium(II) and/or Osmium(II) Complexes of Polypyridyl Ligands Bridged by a Fully Conjugated Aromatic Spacer: Synthesis, Characterization, and Electrochemical and Photophysical Studies

Abstract: A series of mono-, di-, and tetranuclear homo/heterometallic complexes of Ru(II) and Os(II) based on the bridging ligand dppz(11−11‘)dppz (where dppz = dipyrido[3,2-a:2‘,3‘-c]phenazine) (BL) have been synthesized and characterized. This bridging ligand is a long rigid rod with only one rotational degree of freedom and provides complete conjugation between the chromophores. The complexes synthesized are of general formula [(bpy)2Ru−BL]2+, [(phen)2/(bpy)2M−BL−M(bpy)2/(phen)2]4+ (M = Ru(II) and Os(II)), [(bpy)2Ru−BL−Os(bpy)2]4+, and [{(bpy)2Ru−BL}3M]8+. Detailed 1H NMR studies of these complexes revealed that each chiral center does not influence its neighbor because of the long distance between the metal centers and the superimposed resonances of the diastereoisomers, which allowed the unambiguous assignment of the signals, particularly for homonuclear complexes. Concentration-dependent 1H NMR studies show molecular aggregation of the mono- and dinuclear complexes in solution by π−π stacking. Electrospray m...