A comparative study of trace elements in water from various sources in surrounding areas of Nagpur city (India) by instrumental neutron activation analysis

Instrumental neutron activation analysis (INAA) has been used for the determination of 27 elements (Ag, Au, Ba, Br, Ce, Co, Cr, Cs, Eu, Fe, Ga, Hg, Hf, K, La, Mn, Na, Sb, Sc, Se Sr, Th, P, Ta, Tb, Zn and Zr) in 15 water samples collected from different sources (reservoirs, well, borewell, sewage tank, river, rain) in and around Nagpur city (central India) including doubly distilled and a sea water sample from Bombay. Sample residues after evaporation were irradiated at a thermal neutron flux of 10¹²–10¹³ n·cm^–2·s^–1 for 10 min, 1d and 1wk and counted using a HPGe detector and an 4k MCA at different intervals. Several environmental standards from NIST (USA), NIES (Japan) and USGS rock were also analysed for quality assurance. Wide variations in elemental concentrations have been observed in water samples from different sources. Most elemental concentrations in drinking water from various sources, are within ISI/WHO limits. Sea water showed very high concentrations of Ba, Cr, Co, Fe, Hg, Sb, Se and Zn. For doubly distilled and rain waters, however, very low elemental concentrations of Ba, Ce, Fe, Sc, Hg, Se, Sr and Th were observed.     

Monitoring Membrane Protein Conformational Heterogeneity by Fluorescence Lifetime Distribution Analysis Using the Maximum Entropy Method

Due to the inherent difficulty in crystallizing membrane proteins, approaches based on fluorescence spectroscopy have proved useful in elucidating their conformational characteristics. The ion channel peptide gramicidin serves as an excellent prototype for monitoring membrane protein conformation and dynamics due to a number of reasons. We have analyzed conformational heterogeneity in membrane-bound gramicidin using fluorescence lifetime distribution analysis of tryptophan residues by the maximum entropy method (MEM). MEM represents a model-free and robust approach for analyzing fluorescence lifetime distribution. In this paper, we show for the first time, that fluorescence lifetime distribution analysis using MEM could be a convenient approach to monitor conformational heterogeneity in membrane-bound gramicidin in particular and membrane proteins in general. Lifetime distribution analysis by MEM therefore provides a novel window to monitor conformational transitions in membrane proteins.     

Sustainable Synthesis of α-Hydroxycarboxylic Acids by Manganese Catalyzed Acceptorless Dehydrogenative Coupling of Ethylene Glycol and Primary Alcohols**

Herein, we report a straightforward synthesis of valuable α-hydroxycarboxylic acid molecules via an acceptorless dehydrogenative coupling of ethylene glycol and primary alcohols. A bench-stable manganese complex catalyzed the reaction, which is scalable, with the product being isolated with high yields and selectivities under mild conditions. The protocol is environmentally benign, producing water and hydrogen gas as the only byproducts. Methanol can also be used as a C1 source for producing the platform molecule lactic acid, with a high turnover of >10⁴. The methodology was also used to functionalize alcohols derived from natural products and fatty acids. Furthermore, it was applied for synthesizing α-amino acid, α-thiocarboxylic acid, and several drugs and bioactive molecules, including endogenous metabolites, Danshensu, Enalapril, Lisinopril, and Rosmarinic acid. Preliminary mechanistic studies were performed to shed light on the mechanism involved in the reaction.     

Structure-aided drug development of potential neuraminidase inhibitors against pandemic H1N1 exploring alternate binding mechanism

Molecular Diversity - The rate of mutability of pathogenic H1N1 influenza virus is a threat. The emergence of drug resistance to the current competitive inhibitors of neuraminidase, such as...     

Synthesis,characterization and spectroscopic studies of a new ligand [N′-(2-methoxybenzoyl)hydrazinecarbodithioate] ethyl ester and its Mn(II) and Cd(II) complexes: X-ray structural study of Mn(II) complex

A new dithioligand [N′-(2-methoxybenzoyl)hydrazinecarbodithioate] ethyl ester (H₂mbhce, 1) formed complexes [M(Hmbhce)₂]_n {M = Mn(II), Cd(II)} which have been characterized with the help of elemental analyses, magnetic susceptibility measurements, IR, UV–Vis, ¹H and ¹³C NMR and mass spectrometry. [Mn(Hmbhce)₂]_n (2) crystallized in monoclinic system with space group P₂₁/n. In the polymeric structure of 2, the ligand acts as an uninegative tridentate N(1), O(1), S(3) donor and forms a five membered chelate ring with N(1), C(2) and O(1). The intermediate bond lengths (between single and double bond distances) O(1)–C(2) = 1.241(3), N(2)–C(2) = 1.325(3), N(1)–N(2) = 1.393(2), N(1)–C(8) = 1.311(3) ? and C(8)–S(3) = 1.704(2) Å suggest considerable delocalization of charge which develops slightly aromatic character in the chelate ring.     

Fluctuation theorems and orbital magnetism in nonequilibrium state

We study Langevin dynamics of a driven charged particle in the presence as well as in the absence of magnetic field. We discuss the validity of various work fluctuation theorems using different model potentials and external drives. We also show that one can generate an orbital magnetic moment in a nonequilibrium state which is absent in equilibrium.      

Formation of diaryl sulfides and sulfoxides: Synthesis,characterization and structure activity correlation studies

Abstract

The synthesis of a series of stable diarylsulfides and sulfoxides is reported. All the newly synthesized compounds were characterized by ¹H, ¹³C NMR and mass spectroscopic techniques. A detailed mechanistic study indicates that the formation of sulfoxides follows the oxidation. In addition to synthesis, characterization and mechanistic studies, the glutathione peroxidase(GPx) mimetic activity of the newly synthesized compounds is described. It is observed that the diaryl sulfides having a heterocyclic ring attached to the nitrogen atom facilitates the oxidation of the sulfur center to form the corresponding sulfoxides. The substituents attached to the nitrogen atom play an important role in the catalytic activity of the substituted diaryl sulfides. The obtained data supports for the higher antioxidant activity of diaryl sulfides than that of the corresponding sulfoxides.     

Altered Membrane Mechanics Provides a Receptor-Independent Pathway for Serotonin Action

Serotonin, an important signaling molecule in humans, has an unexpectedly high lipid membrane affinity. The significance of this finding has evoked considerable speculation. Here we show that membrane binding by serotonin can directly modulate membrane properties and cellular function, providing an activity pathway completely independent of serotonin receptors. Atomic force microscopy shows that serotonin makes artificial lipid bilayers softer, and induces nucleation of liquid disordered domains inside the raft-like liquid-ordered domains. Solid-state NMR spectroscopy corroborates this data at the atomic level, revealing a homogeneous decrease in the order parameter of the lipid chains in the presence of serotonin. In the RN46A immortalized serotonergic neuronal cell line, extracellular serotonin enhances transferrin receptor endocytosis, even in the presence of broad-spectrum serotonin receptor and transporter inhibitors. Similarly, it increases the membrane binding and internalization of oligomeric peptides. Our results uncover a mode of serotonin–membrane interaction that can potentiate key cellular processes in a receptor-independent fashion.     

Facile synthesis of additive-assisted nano goethite powder and its application for fluoride remediation

The present article describes a novel synthesis route for nano-sized goethite (α-FeOOH) using hydrazine sulphate as an additive. The X-ray diffraction (XRD) peaks of synthesized powder matched well with those of α-FeOOH. Transmission electron microscopy (TEM) showed the particles of irregular shape in the range of 1–10 nm. Batch adsorption experiments for fluoride uptake were performed to study the influence of various experimental parameters such as contact time (10 min to 7 h), initial fluoride concentration (10–150 mg L⁻¹), pH (2–11.6) and the presence of competing anions. The time data fitted well to pseudo-second-order kinetic model. The fluoride removal passed through broad maxima in pH ranges of 6–8. High adsorption capacity of 59 mg g⁻¹ goethite was obtained. The isothermic data fitted well to Freundlich model. The presence of other ions namely chloride and sulphate adversely affected fluoride removal. Fluoride from contaminated water sample could be successfully brought down from 10.25 to 0.5 mg L⁻¹.     

Near neighbour ligand hyperfine splittings in the e.p.r. spectra of copper(II) complexes

X-band e.p.r. spectra from mixed ligand complexes Cu(btc)-(Hy), Cu(TPA)(Hy) and Cu(Sal)(TPA), have been derived from the spectra of suitable reaction mixtures in CHCl₃ at 25° C (Sal⁻ = salicyladehydate, TPA⁻ = thiopicolineanilide, Hy⁻ = 8-hydroxyquinolinate and btc⁻ =N-benzoyl-N′N′-diethylcarbamide). A digital data acquisition instrument and a personal computer were used for this purpose. The¹⁴N hyperfine splittings observed in these complexes have shown that the observed increase in spin density on the coordinating atoms of one ligand, at the expense of that on the other, is unlikely to be associated with the covalent bonding involving metal d _x ²− _y ²-orbital. Covalent bonding involving metal 4s-orbital component of the unpaired electron orbital has been suggested to be responsible for the observed changes in electron delocalization. This work was carried out during the visit of Drs Z. R. Baratova and P. M. Solozhenkin to India in 1991.