Showing papers by "National Chemical Laboratory published in 2007"
TL;DR: These studies will help in designing a rational enzymatic strategy for the synthesis of nanomaterials of different chemical composition, shapes and sizes as well as their separation.
Abstract: Synthesis of silver nanoparticles using α-NADPH-dependent nitrate reductase and phytochelatin in vitro has been demonstrated for the first time. The silver ions were reduced in the presence of nitrate reductase, leading to the formation of a stable silver hydrosol 10–25 nm diam. and stabilized by the capping peptide. The nanoparticles were characterized by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy and UV-Vis absorption. These studies will help in designing a rational enzymatic strategy for the synthesis of nanomaterials of different chemical composition, shapes and sizes as well as their separation.
566 citations
TL;DR: The studies indicate that oral and nasal administration of insulin loaded chitosan reduced gold nanoparticles has led to improved pharmacodynamic activity and prove to be promising in controlling the postprandial hyperglycemia.
Abstract: Colloidal metallic systems have been recently investigated in the area of nanomedicine. Gold nanoparticles have found themselves useful for diagnostic and drug delivery applications. Herein we have reported a novel method for synthesis of gold nanoparticles using a natural, biocompatible and biodegradable polymer; chitosan. Use of chitosan serves dual purpose by acting as a reducing agent in the synthesis of gold nanoparticles and also promotes the penetration and uptake of peptide hormone insulin across the mucosa. To demonstrate the use of chitosan reduced gold nanoparticles as carriers for drug delivery, we report herein the transmucosal delivery of insulin loaded gold nanoparticles. Gold nanoparticles were prepared using different concentrations of chitosan (from 0.01% w/v up to 1% w/v). The gold nanoparticles were characterized for surface plasmon band, zeta potential, surface morphology, in vitro diffusion studies and fluorescence spectroscopy. The in vivo studies in diabetic male Wistar rats were carried out using insulin loaded chitosan reduced gold nanoparticles. Varying concentrations of chitosan used for the synthesis of gold nanoparticles demonstrated that the nanoparticles obtained at higher chitosan concentrations (>0.1% w/v) were stable showing no signs of aggregation. The nanoparticles also showed long term stability in terms of aggregation for about 6 months. Insulin loading of 53% was obtained and found to be stable after loading. Blood glucose lowering at the end of 2 h following administration of insulin loaded gold nanoparticles to diabetic rats was found to be 30.41 and 20.27% for oral (50 IU/kg) and nasal (10 IU/kg), respectively. Serum gold level studies have demonstrated significant improvement in the uptake of chitosan reduced gold nanoparticles. The synthesis of gold nanoparticles using a biocompatible polymer, chitosan would improve its surface properties for binding of biomolecules. Our studies indicate that oral and nasal administration of insulin loaded chitosan reduced gold nanoparticles has led to improved pharmacodynamic activity. Thus, chitosan reduced gold nanoparticles loaded with insulin prove to be promising in controlling the postprandial hyperglycemia.
548 citations
TL;DR: A simple pheromone-guided mechanism to improve the performance of PSO method for optimization of multimodal continuous functions is explored and numerical results comparisons with different metaheuristics demonstrate the effectiveness and efficiency of the proposed PSACO method.
321 citations
TL;DR: In this paper, the authors present a review on the present status of anionic polymerization of important non-polar and polar vinyl monomers, including recent developments, and discuss some important scientific and industrial applications.
207 citations
TL;DR: The strain of Penicillium janthinellum NCIM 1171 was subjected to mutation involving treatment of Ethyl Methyl Sulfonate for 24h followed by UV-irradiation for 3min and mutants showed enhanced cellulase production, clearance zone on Avicel containing plate, and rapid growth on Walseth cellulose agar plates containing 0.2% 2-deoxy-d-glucose.
206 citations
TL;DR: In this article, fine particles of cobalt ferrite were synthesized by the sol?gel method and X-ray diffraction studies were carried out to elucidate the structure of all the samples.
Abstract: Fine particles of cobalt ferrite were synthesized by the sol?gel method. Subsequent heat treatment at different temperatures yielded cobalt ferrites having different grain sizes. X-ray diffraction studies were carried out to elucidate the structure of all the samples. Dielectric permittivity and ac conductivity of all the samples were evaluated as a function of frequency, temperature and grain size. The variation of permittivity and ac conductivity with frequency reveals that the dispersion is due to Maxwell?Wagner type interfacial polarization in general, with a noted variation from the expected behaviour for the cold synthesized samples. High permittivity and conductivity for small grains were explained on the basis of the correlated barrier-hopping model.
161 citations
TL;DR: HPLC-MS and XPS analysis of dye degradation using as-synthesized nanoparticles exposed to air and water confirmed that the reductive or oxidative degradation capability of Fe-Ni nanoparticles is decided by the time and type of catalyst aging process.
Abstract: The degradation of Orange G, a monoazo dye, in aqueous solutions was investigated using as-synthesized and stored Fe-Ni bimetallic nanoparticles. Batch experiments with a nanocatalyst loading of 3 g/L showed complete dye degradation (150 mg/L) after 10 min of reaction time. HPLC-MS analysis of the degradation products showed that as-synthesized nanoparticles reductively cleaved the azo linkage to produce aniline as the major degradation product. However, 1-year-stored nanoparticles showed an oxidative degradation of Orange G through a hydroxyl-radical induced coupling of parent and/or product molecules. XPS analysis in corroboration with HPLC-MS data showed that the surface chemistry between Fe and Ni in as-synthesized and stored nanoparticles play a crucial role in directing the mode of degradation. Reductive dye degradation using as-synthesized nanoparticles proceeded through hydride transfer from nickel, whereas formation of a Fe2+ -Ni(0) galvanic cell in stored nanoparticles generated hydroxyl radicals from water in a nonFenton type reaction. The latter were responsible for the generation of radical centers on the dye molecule, which led to a coupling-mediated oxidative degradation of Orange G. The generation of hydroxyl radicals is further substantiated with radical quenching experiments using ascorbic acid indicating that stored nanoparticles degrade Orange G through a predominantly oxidative mechanism. HPLC-MS and XPS analysis of dye degradation using as-synthesized nanoparticles exposed to air and water confirmed that the reductive or oxidative degradation capability of Fe-Ni nanoparticles is decided by the time and type of catalyst aging process.
151 citations
TL;DR: In this article, the production of lactic acid from sugarcane bagasse cellulose, one of the abundant biomass materials available in India, was studied, where the bagasse was chemically treated to obtain a purified sample, which is much more amenable to cellulase enzyme attack than bagasse itself.
148 citations
TL;DR: The magnetic properties of the nanoparticles indicate their strongly interacting nature as mentioned in this paper, and they are superparamagnetic at room temperature, with a super-paramagnetic blocking temperature of 200 K.
146 citations
TL;DR: In this article, an autocombustion method was used to synthesize Mn doped ZnO nanowires, which were characterized by X-ray diffraction and transmission electron microscopy.
138 citations
TL;DR: In this paper, a detailed investigation on the production of chlorine-free benzaldehyde in the solvent-free oxidation of benzyl alcohol by O2 over nano-gold supported on U3O8 has been carried out.
TL;DR: In this paper, X-ray photoelectron spectroscopy (XPS) was used for the characterization of surface composition of core and shell nanoparticles, and the core-shell nanoparticles were synthesized using sodium bis(2-ethylhexyl) sulfosuccinate (AOT)/n-heptane/water microemulsion technique.
TL;DR: In this article, a total of seven nonlinear models have been developed using the artificial neural networks (ANN) methodology for the estimation of gross calorific value (GCV) with a special focus on Indian coals.
TL;DR: In this article, the acid properties of Cex-Aly-MCM-41 with different Ce/Al/Si atomic ratios were examined by pyridine-FTIR and ammonia-TPD methods.
TL;DR: In this article, the authors reported selective NO x sensing characteristics of Al-doped ZnO synthesized in the form of porous pellets sintered at 350°C.
Abstract: Although ZnO is studied intensively as a sensing material, there are limited reports available on aluminum-doped ZnO (AZO) as a NO x sensor. This paper reports selective NO x sensing characteristics of Al-doped ZnO synthesized in the form of porous pellets sintered at 350 °C. The salient feature of our experimental results is that our sensor can detect small concentrations of NO x at lower operating temperature. It is also observed that as compared to gases such as SO x , HCl, LPG, H 2 S, H 2 , ammonia, alcohol and acetone it selectively detects NO x due to Al-doping. The amount of Al in ZnO during synthesis is varied between 1 and 10 wt%. Our sensor senses NO x concentration as low as 20 ppm at 100 °C with a %response of 11 and a %response of 740 at 300 °C for 1 wt% Al. Of all the compositions with Al-doping, 1 wt% is found to give best results. Sensing experiments carried out at 350 °C, however, do not show any significant improvement in the gas sensing properties. The phase contents and lattice parameters were determined by XRD and the average particle size was obtained using Scherrer formula. A probable mechanism for sensing NO x involving oxygen ion adsorption and desorption on the surface of sensor has been suggested.
TL;DR: In this paper, a highly efficient and rapid synthesis of 2-amino-4-arylthiazoles from α-bromoketone and thiourea/thioamide is described using room temperature ionic liquid at ambient conditions.
TL;DR: In this paper, it was proposed that cellulose is hydrolyzed by in situ generated acid sites to form glucose, and glucose is immediately reduced to sorbitol over the metal catalyst.
Abstract: Cellulose is cracked over supported Pt or Ru catalysts under hydrogenolysis conditions in water to give sorbitol as a main product. Among the catalysts tested, Pt/γ-Al2O3 gave the highest yield and selectivity, and this catalyst was recyclable in repeated runs. It is proposed that cellulose is hydrolyzed by in situ generated acid sites to form glucose, and glucose is immediately reduced to sorbitol over the metal catalyst.
TL;DR: A composite intraspecific linkage map of chickpea was developed by integrating individual maps developed from two F8:9 RIL populations with one common parent along with three yield related traits: double podding, seeds per pod and seed weight.
Abstract: A composite intraspecific linkage map of chickpea was developed by integrating individual maps developed from two F8:9 RIL populations with one common parent. Different molecular markers viz. RAPD, ISSR, RGA, SSR and ASAP were analyzed along with three yield related traits: double podding, seeds per pod and seed weight. A total of 273 markers and 186 RILs were used to generate the map with eight linkage groups at a LOD score of ≥3.0 and maximum recombination fraction of 0.4. The map spanned 739.6 cM with 230 markers at an average distance of 3.2 cM between markers. The predominantly used SSR markers facilitated identification of homologous linkage groups from the previously published interspecific linkage map of chickpea and confirmed conservation of the SSR markers across the two maps as well as the variation in terms of marker distance and order. The double podding gene was tagged by the markers NCPGR33 and UBC249z at 2.0 and 1.1 cM, respectively. Whereas, seeds per pod, was tagged by the markers TA2x and UBC465 at 0.1 and 1.8 cM, respectively. Eight QTLs were identified that influence seed weight. The joint map approach allowed mapping a large number of markers with a moderate coverage of the chickpea genome and few linkage gaps.
TL;DR: In this article, an integrated reaction engineering based mathematical model for clinker formation in cement industry is presented, where separate models for pre-heater, calciner, rotary kiln and cooler are initially developed and coupled together to build an integrated simulator.
TL;DR: The jack-knife success rate thus obtained on the benchmark dataset constructed by Shen and Chou is 71.23%, indicating that the novel pseudo amino acid composition approach with PSSM and SVM classifier is very promising and may at least play a complimentary role to the existing methods.
TL;DR: In this paper, the effect of a coarse surface layer of bed material inhibiting the release of fine subsurface material in mountain rivers was investigated and it is hypothesized that the overestimate is due to a failure to account for the effect that a coarse, coarse layer of ground bed material hinders the free flow of fine surface material.
Abstract: Existing bed-load transport formulas may overestimate the transport rate in mountain rivers by two orders of magnitude or more. Recently published field data sets provide an opportunity to take a fresh look at the bed-load transport relationship and it is hypothesized that the overestimate is due to a failure to account for the effect of a coarse surface layer of bed material inhibiting the release of fine subsurface material. Bed-load transport is determined as gs =aρ(q− qc ) where q =water discharge per unit width; qc =critical value for initiation of bed material movement; ρ =water density; and a =coefficient. The gs ∕q relationship is typically piecewise linear, characterized by two transport phases with, respectively, low and high rates of change. Twenty-one flume and 25 field data sets were used to quantify the relationship for Phase 2. The flume data confirm the dependence of a on S1.5 , where S =channel slope, in agreement with earlier studies. The field data additionally show that a varies invers...
TL;DR: The nature of the relations between Parkinson’s disease and dementia with Lewy bodies, and what can be learned from them about the causes of dementia in patients with established Parkinson's disease are discussed.
Abstract: Parkinson's disease and dementia with Lewy bodies are two common presentations of a single, underlying disease process (Lewy body disease) which is thought to be related to dysregulation of the synaptic protein, alpha-synuclein. This article discusses the nature of the relations between Parkinson's disease and dementia with Lewy bodies, and what can be learned from them about the causes of dementia in patients with established Parkinson's disease. This is an area of clinical practice which is of increasing importance as greater numbers of ageing patients survive longer with good treatment of their motor symptoms. Precise use of terminology and a clear understanding of the biological substrates underlying symptom formation are particularly helpful to both clinicians and patients.
TL;DR: In this paper, the magnetostrictive properties of sintered cobalt ferrite derived from nanocrystalline powders synthesized by three different low-temperature methods (citrate, coprecipitation and autocombustion) and the high temperature ceramic method have been compared.
Abstract: The magnetostrictive properties of sintered cobalt ferrite derived from nanocrystalline powders synthesized by three different low-temperature methods (citrate, coprecipitation and autocombustion) and the high-temperature ceramic method have been compared. A strong dependence of the magnetostrictive strain is observed on the initial morphology of the ferrite particles and the microstructure of the final sintered product. The nanoparticles synthesized by the autocombustion method, with a flaky and porous morphology, give a sintered material with small grains. Maximum magnetostriction is found to be decreased with increasing grain size. However, no correlation is observed between the initial particle size of the powders or the sintered density and magnetostriction. Maximum magnetostriction values of 197, 184, 159, and 135 ppm are obtained for the sintered samples with average grain sizes of 8 μm (combustion), 17 μm (citrate), 23 μm (coprecipitation), and >25 μm (ceramic), respectively.
TL;DR: In this paper, a computational fluid dynamics (CFD) model was developed to simulate the unsteady gas−liquid flow in a bubble column using commercial code FLUENT 6.2.
Abstract: This paper focuses on the modeling of flow and mixing in a bubble column reactor operated at high gas velocities (up to 0.40 m/s). A dual-tip conductivity probe was used to measure local void properties such as local time-averaged gas holdup, chord length distribution, bubble velocity distribution, and interfacial area. Chord length distribution was converted to bubble size distribution, using the backward transformation method. Liquid-phase mixing time measurements were conducted using a conductivity probe. A computational fluid dynamics (CFD) model was developed to simulate the unsteady gas−liquid flow in a bubble column using commercial code FLUENT 6.2. The time-averaged flow properties predicted by CFD simulations were compared with the experimental data. The role of unsteady flow structures in mixing was studied. The “multiple snapshots” approach was used to simulate the mixing time using CFD. The mixing times that were predicted for all superficial gas velocities compared favorably to the measured v...
TL;DR: For the first time an alkali stable endoglucanase from alkalothermophilic Thermomonospora sp.
Abstract: Use of cellulase for denimwashing is a standard eco-friendly technique to achieve desirable appearance and softness for cotton fabrics and denims. But enzymatic washing of denim till date involved acid cellulase (Tricho- derma reesei) and neutral cellulase (Humicola isolens) the use of which has a drawback of backstaining of the indigo dye on tothefabric.ThoughithasbeensuggestedthatpHisamajor factor in controlling backstaining there are no reports on use of cellulase under alkaline conditions for denim washing. In this study for the first time an alkali stable endoglucanase from alkalothermophilic Thermomonospora sp. (T-EG) has been used for denim biofinishing under alkaline conditions. T-EG is effective in removing hairiness with negligible weight loss and imparting softness to the fabric. Higher abrasive activity with lower backstaining was a preferred property for denim biofinishing exhibited by T-EG. The activities were comparable to acid and neutral cellulases that arebeingregularly used.Theenzymewasalsoeffective under non-buffering conditions which is an added advantage for use in textile industry. A probable mechanism of enzymatic finishing of cotton fabric has been represented based on the unique properties of T-EG. Biotechnol. Bioeng. 2007;96: 48-56. 2006 Wiley Periodicals, Inc.
TL;DR: In this paper, the use of different lower and higher alcohols for the synthesis of methyl, ethyl, propyl and octyl fatty acid esters by transesterification of vegetable oil (triglycerides) with respective alcohols also known as Bio-diesel and Bio-lubricants was studied in detail.
TL;DR: In this paper, a direct synthetic route for the preparation of Sn-SBA-15 materials with nSi/nSn ratios ranging from 100 to 10 under milder acidic conditions than normally employed for the pre-processing of Si-Saba-15 is reported.
TL;DR: Ionic liquids are designer molecules which can efficiently replace the conventional organic solvents used in chemical processes and operations as discussed by the authors, but very few of them have actually been commercialized.
Abstract: Ionic liquids are designer molecules which can efficiently replace the conventional organic solvents used in chemical processes and operations. Although a number of such applications have been reported in the literature for almost a decade, very few have actually been commercialized. This paper details the different applications claimed and examines the issues and barriers which obstruct the rapid commercialization of ionic liquids. It identifies further courses of action required for the assessment and realization of the advantages of ionic liquids.
TL;DR: In this paper, the poly(o-anisidine-co-o-toluidine) coatings were synthesized on copper substrates by electrochemical copolymerization of o-nisidine with o-toline using sodium salicylate as supporting electrolyte.
TL;DR: The experimental results of the LPG sensing studies reveal that the nano-sized CdO powder synthesized by a simple co-precipitation method is a suitable material for the fabrication of theLPG sensor.