Balachandran Unni Nair

Interaction of DNA with [Cr(Schiff base)(H2O)2]ClO4

The binding of Schiff base complexes of chromium(III) of the type [Cr(salen)(H(2)O)(2)](+) and [Cr(salprn)(H(2)O)(2)](+), where salen denotes 1,2-bis(salicylideneamino)ethane and salprn denotes 1,3-bis(salicylideneamino)propane to calf thymus DNA has been investigated by absorption, emission, circular dichroism, melting temperature and viscosity measurements. These chromium(III) complexes showed absorption hyperchromicity accompanied by red shift in charge transfer band, fluorescence enhancement, increase in melting temperature, some structural changes in CD spectra and changes in specific viscosity when bound to calf thymus DNA. The binding constant K(b) has been determined from absorption measurements for both the complexes and found to be (2.5+/-0. 4)x10(3) M(-1) for [Cr(salen)(H(2)O)(2)](+) and (1.7+/-0.3)x10(4) M(-1) for [Cr(salprn)(H(2)O)(2)](+). From the binding stoichiometry of DNA-[Cr(salprn)(H(2)O)(2)](+), the number of binding site size has been determined and found to be ten base pairs per bound complex molecule. The chromium(III) complexes also bring about single strand cleavage in plasmid DNA. The experimental results show that the chromium(III) complexes bind to DNA by non-intercalative mode. Major groove binding is the preferred mode of interaction for these Schiff base complexes of chromium(III).

Photooxidation of DNA by a cobalt(II) tridentate complex

[Co(bzimpy)(2)], where bzimpy is 2,6-bis(benzimidazol-2-yl)pyridine was synthesized and characterized by ESI-MS (electrospray ionization mass spectrometry), UV-visible and fluorescence spectra. Absorption titration and thermal denaturation experiments indicate that the complex binds to DNA with moderate strength. Viscosity measurement shows that the mode of binding could be surface binding. Fluorescence study shows that the fluorescence intensity of the complex decreases with increasing concentrations of DNA, which is due to the photoelectron transfer from guanine base to excited MLCT (metal to ligand charge transfer) state of the complex. Photoexcitation of the complex in the MLCT region in the presence of plasmid DNA has been found to give rise to nicking of DNA.

Biosorption of cadmium metal ion from simulated wastewaters using Hypnea valentiae biomass: A kinetic and thermodynamic study

Present study deals with the evaluation of biosorptive removal of cadmium by red macro alga Hypnea valentiae. Experiments have been carried out to find the effect of various parameters such as initial cadmium concentration, experimental pH and temperature on the biosorption potential of H. valentiae. Optimum pH for biosorption of cadmium was found to be 6+/-0.3. A maximum removal of about 17mg of cadmium per g of micro algae was observed at pH 6.0 for 250mgL(-1) solution of cadmium. Kinetics of cadmium biosorption by H. valentiae biomass is better described by pseudo first order kinetic model. The equilibrium isotherm data are very well represented by Langmuir isotherm equation, which confirmed the monolayer coverage of cadmium onto H. valentiae biomass. Various thermodynamic parameters such as change in enthalpy, free energy and entropy were estimated. It was also clearly observed that the presence of neutral salts and other metal ions affected the cadmium uptake behavior of the biomass considerably.

Oxidative cleavage of DNA by tridentate copper (II) complex.

Copper (II) complex 1 having planar tridentate ligand, bzimpy, where bzimpy is 2,6-bis(benzimidazo-2-yl) pyridine was synthesized and characterized by UV-visible, FAB (fast atom bombardment) mass and infrared spectroscopy. From absorption titration data, the binding constant of Cu(II) with DNA was calculated to be (1.8+/-0.02)x10(4) M(-1). Thermal denaturation study of DNA with 1 revealed deltaT(m) of 5+/-0.5 degrees C. Viscosity measurement showed that complex binds with DNA through intercalative mode. Copper (II) complex induces cleavage in plasmid DNA in the presence of coreductants such as ascorbic acid or glutathione.

Recouping the wastewater: a way forward for cleaner leather processing

Abstract Leather processing employs copious amounts of water. This leads to the generation of enormous amounts of liquid effluent. The high effluent volume requires huge investments for effluent treatment plants in order to meet the required specification for the discharge of liquid effluents to various water bodies. Increasingly therefore, water use minimization in leather processing assumes greater significance due to increased treatment costs. End-of-pipe treatment methods alone do not meet the requirements and hence, in-plant control measures are gaining importance. The new era of cleaner technology has begun in leather processing. Pre-tanning and tanning operations contribute about 57% of the water consumption in leather processing and the washings about 35%. The proper adoption of integrated cleaner technologies provides a viable solution to the conservation of water in leather processing. This paper presents an integrated approach for water use minimization through recycling and optimization in leather processing. The integrated approach provides considerable reduction in the use of process water.

Synthesis, characterization and DNA binding studies of a ruthenium(II) complex

[Ru(bzimpy)(2)]Cl(2), where bzimpy is 2,6-bis(benzimidazol-2-yl) pyridine was synthesized and characterized by ESI-MS, UV-Visible, (1)H NMR and fluorescence spectra. Absorption titration and thermal denaturation experiments indicate that the complex binds to DNA with moderate strength. Viscosity measurement shows that the mode of binding could be surface binding. Fluorescence study shows that the fluorescence intensity of the complex decreases with increasing concentrations of DNA, which is due to the photoelectron transfer from guanine base to (3)MLCT of the complex. Photoexcitation of the complex in the MLCT region in the presence of plasmid DNA has been found to give rise to nicking of DNA.

Application of a chemically modified green macro alga as a biosorbent for phenol removal.

Phenol and substituted phenols are toxic organic pollutants present in tannery waste streams. Environmental legislation defines the maximum discharge limit to be 5-50 ppm of total phenols in sewers. Thus the efforts to develop new efficient methods to remove phenolic compounds from wastewater are of primary concern. The present work aims at the use of a modified green macro alga (Caulerpa scalpelliformis) as a biosorbent for the removal of phenolic compounds from the post-tanning sectional stream. The effects of initial phenol concentration, contact time, temperature and initial pH of the solution on the biosorption potential of macro algal biomass have been investigated. Biosorption of phenol by modified green macro algae is best described by the Langmuir adsorption isotherm model. Biosorption kinetics of phenol onto modified green macro algal biomass were best described by a pseudo second order model. The maximum uptake capacity was found to be 20 mg of phenol per gram of green macro algae. A Boyd plot confirmed the external mass transfer as the slowest step involved in the biosorption process. The average effective diffusion coefficient was found to be 1.44 x 10(-9) cm(2)/s. Thermodynamic studies confirmed the biosorption process to be exothermic.

Synthesis, characterization and DNA binding studies of new ruthenium(II)bisterpyridine complexes

Two new ruthenium(II) complexes, [Ru(itpy)2](PF6)2, 1 and [Ru(bitpy)2](PF6)2 2, were synthesized and characterized by ESI-Mass, UV-Visible, 1H NMR, fluorescence spectroscopy and cyclic voltammetry. Complex 1 has been characterized crystallographically. Interaction of these complexes with CT-DNA has been studied using absorption and CD spectra. Absorption spectral titration and CD spectral measurements show that complex 1 binds with DNA through intercalation. Complex 2 on the other hand shows dual mode of binding to DNA, groove binding as well as intercalation. Photo nuclease activity of these complexes has been studied using agarose gel electrophoresis and both the complexes have been shown to exhibit photonuclease activity. However, complex 1 has been found to show higher DNA cleaving efficiency compared to complex 2.

Recent Trends in Leather Making: Processes, Problems, and Pathways

Leather processing has emerged as an important economic activity in several developing countries. Awareness of environmental problems has increased considerably and during recent years protecting environment has become a global issue. Currently the leather processing industry is going through a phase change due to global environmental regulations. The article summarizes the current leather processing methods with their rationale and environmental problems. It has been revealed that pretanning and tanning processes contribute 80–90% of the total pollution load (BOD, COD, TS, TDS, Cr, S2−, sludge, etc.). Further, toxic gases like ammonia and hydrogen sulfide are also emitted. Volatile organic compounds, heavy metals, and carcinogenic arylamines from posttanning and finishing operations are also creating severe concern. Apart from this, a great deal of solid wastes like lime sludge from tannery and chrome sludge from effluent treatment plants are being generated. Advanced processing techniques as well as effluent treatment strategies for combating environmental and human health risks are reviewed in detail. The leather processing industry in various countries, however, is facing a serious challenge from the public and government. This is in spite of the implementation of several advanced processing techniques and treatment systems. Hence, there is a need to revamp leather processing methods anew for the sustainability of leather industry. Some of the novel concepts in leather processing are briefly mentioned and discussed.

Methane budget from paddy fields in India

Abstract Results of national methane campaign launched in 1991 to assess methane budget from Indian paddy fields are reported. The campaign involved a number of scientific institutions and universities with National Physical Laboratory at Delhi operating as a nodal agency and covered most of the major rice growing regions of India. Methane emission rates ranged between −0.64 and 84.1 mg −2 h −1 . The methane budget from Indian paddies has been estimated to be around 4.0 TgY −1 with a range between 2.7 to 5.4 TgY −1 .