Showing papers by "National Chemical Laboratory published in 1994"
TL;DR: In this article, the authors review the experimental evidence, especially the anomalous experimental observations of interest to engineers, concerned with enhancement (which is sometimes rather dramatic) in heat, mass and momentum transfer during the flow of such sliding fluids.
158 citations
TL;DR: In this article, the effect of the SiO 2 Al 2 O 3 ratio, alkalinity, gel dilution, amount of the seed crystals and alkali metal, nature of the organic template, and time and temperature of the synthesis was investigated.
83 citations
TL;DR: In this paper, the nuclear and side-chain bromination of activated aromatic substrates has been achieved in high yields and substantial regioselectivity with N-Bromosuccinimide (NBS) over HZSM-5.
70 citations
TL;DR: This study demonstrates that microsatellite-derived DNA fingerprints are ideally suited for the identification of rice genotypes and can be very useful in monitoring and aiding gene introgression from wild rice into cultivars.
Abstract: In this report we describe the use of five oligonucleotide probes, namely (GATA)4, (GACA)4, (GGAT)4, (GAA)6 and (CAC)5, to reveal highly polymorphic DNA regions in rice. With each of the oligonucleotide probes, the level of polymorphism was high enough to distinguish several rice genotypes. Moreover, individual plants of one cultivar showed the same cultivar-specific DNA fingerprint. The multilocus fingerprint patterns were somatically stable. Our study demonstrates that microsatellite-derived DNA fingerprints are ideally suited for the identification of rice genotypes. As the majority of the probes detected a high level of polymorphism, they can be very useful in monitoring and aiding gene introgression from wild rice into cultivars.
68 citations
TL;DR: Embryogenic masses were obtained from immature leaves of peanut cultured on a medium containing 20 mg/l 2,4-D and developed into somatic embryos, which germinated and survived in sand:soil mixture and were grown to maturity.
Abstract: Embryogenic masses were obtained from immature leaves of peanut (Arachis hypogaea L.) cultured on a medium containing 20 mg/l 2,4-D. Somatic embryos developed from these masses following transfer to a medium containing 3 mg/l 2,4-D. The embryo morphology was quite variable. Following transfer to hormone-free medium, these embryos germinated. Shoot elongation was obtained in 25% of the embryos following transfer to a medium supplemented with 0.5 mg/l each of BAP and Kn. The plants grown in vitro by this method survived in sand:soil mixture and were grown to maturity.
56 citations
TL;DR: The life time of a dissolving polymeric particle in a hydrodynamic field is predicted by building up a model that includes the phenomenon of reptation of the macromolecules, disengagement of these molecules from the gel-liquid interface and also diffusion in the boundary layer surrounding the liquid interface as discussed by the authors.
56 citations
TL;DR: In this article, an energy efficient and safe conversion of methane to syngas is possible by carrying out the exothermic oxidation of methane and the endothermic reaction of methane with steam and CO 2 simultaneously with the same NiO/CaO catalyst.
Abstract: An energy efficient and safe conversion of methane to syngas is possible by carrying out the exothermic oxidation of methane and the endothermic
reaction of methane with steam and CO 2 simultaneously with the same NiO/CaO catalyst. By coupling the two reactions and manipulating the relative
concentrations of CH 4 , O 2 , CO 2 , and steam in the feed, the overall methane-to-syngas conversion can be made mildly
exothermic, thermoneutral, or mildly endothermic. The H 2 /CO ratio of the product can be varied from roughly 1.5 to 2.5.
54 citations
TL;DR: Synthesis of 5-Me-dC-amidite regiospecifically tethered at C4, with triethylenetetramine and spermine and their site specific incorporation into DNA to obtain oligonucleotide-polyamine conjugates is reported.
50 citations
TL;DR: In this paper, the authors compared the properties of TS-2 and VS-2 with aqueous hydrogen peroxide and showed that the principal path is probably homolytic in the case of the latter.
50 citations
TL;DR: In this article, the role of delocalised α-silylmethyl amine radical cation as reactive intermediate in PET reaction is described, and the authors show that the reactive intermediate can be used to produce pyrrolidines and piperidines.
48 citations
TL;DR: In this paper, the thermal decomposition and surface area of the resulting MgO are found to be strongly influenced by the preparation conditions of basic magnesium carbonate, and different modes of mixing in the precipitation and also by ageing the precipitate for different periods (0.5-96 h).
TL;DR: In this article, a variety of techniques including XRD, IR, AAS, SEM, UV-Vis, XANES and catalytic testing in hydroxylation of phenol were used.
Abstract: Crystalline titanium containing silica analog of ZSM-48 (TS-48) samples were synthesized using soluble peroxytitanate, fumed silica and diamino octane. All samples were characterized using a variety of techniques including XRD, IR, AAS, SEM, UV-Vis, XANES and catalytic testing in hydroxylation of phenol. Data suggest that titanium in these materials is linked to the framework. However, it was impossible to incorporate more than about 2 wt% Ti in the zeolite lattice. TS-48 samples prepared by this method had no activity for hydroxylation of phenol in the presence of hydrogen peroxide. The lack of activity of this material even though it showed all of the regular characteristics of other catalytically active titanium silicalites (i.e., TS-1 and TS-2) could be due either to diffusional limitations or to subtle differences in titanium environment.
TL;DR: In this paper, the importance of microbially enhanced oil recovery (MEOR) along with the historical background and proposed mechanisms involved in MEOR was stressed along with a historical overview of the MEOR process.
TL;DR: In this paper, a TS-1-H 2 O 2 combination has been shown to display remarkable reaction selectivity in the liquid-phase oxidative cleavage of oximes to carbonyl compounds in excellent yields.
TL;DR: In this article, an unprecedented selectivity and reactivity in heterogeneous asymmetric catalytic dihydroxylation of olefins has been achieved using 3,6-(9- O -bisdihydroquinyl) pyridazine and 3, 6-(9 - O -binidyl)pyridine immobilized on a polyethylene (PE) polymer backbone.
TL;DR: An efficient protocol has been developed for inducing direct somatic embryogenesis from mature embryo axes in chickpea and Histological sections confirmed the direct origin of embryos from the explant.
TL;DR: In this article, the synthesis, characterization and catalytic properties of PSH-3/MCM-22 are reported, and detailed characterization using X-ray, TGA/DTA, MAS NMR are described.
Abstract: The synthesis, characterization and catalytic properties of PSH-3/MCM-22 are reported. Crystallization kinetics and detailed characterization using X-ray, TGA/DTA, MAS NMR are described. X-ray results show the zeolite to possess an orthorhombic unit cell. Adsorption and catalytic studies indicate that the zeolite has an internal void volume in between that of ZSM-12 and beta.
TL;DR: In this article, a high piezoresistive effect has been observed in semiconducting polyvinylidene fluoride as well as polyphenylene sulfide composites containing metallic fillers.
TL;DR: In this article, two Fe-Mo catalysts have been prepared from ferric nitrate and ammonium paramolybdate, one following a conventional procedure and the other by a new precipitation procedure in a buffer medium, which leads to small, uniform (0.3 μm size) particles and a homogeneous morphology of phases as seen by scanning electron microscopy.
Abstract: Two samples of Fe-Mo catalysts have been prepared from ferric nitrate and ammonium paramolybdate, one following a conventional procedure and the other by a new precipitation procedure in a buffer medium. The evolution of different Fe-Mo phases, from the fresh precipitate to the aged and then to the calcined state, has been followed by FT-IR spectroscopy. All the spectral vibrations have been related to different coordination spheres of Mo and Fe ions in the samples and a comparison with a commercial catalyst of similar composition has been made. The new preparation procedure leads to small, uniform (0.3 μm size) particles and a homogeneous morphology of phases as seen by scanning electron microscopy. Additionally, a higher surface area (10.3 m 2 /g), lower bulk density (0.66 g/cm 3 ), a methanol conversion efficiency of >99% and an HCHO selectivity of 95% distinguish this sample from the conventionally prepared one. Better thermal stability of this sample is inferred from the IR spectral and XRD analyses of the heat-treated (up to 800°C) samples and is related to the interaction between Fe 2 (MoO 4 ) 3 and MoO 3 phases
TL;DR: Production of microspore-derived embryos from cultured anthers is now a well established technique for the isolation of homozygous lines in many crop plants and the effect of cold pretreatment, hormone regime and sucrose concentration are described.
Abstract: Production of microspore-derived embryos from cultured anthers is now a well established technique for the isolation of homozygous lines in many crop plants. We describe here a culture method for embryo induction and plant regeneration from anthers of four sunflower genotypes. For preliminary experiments, anthers of uninucleate microspores were cultured on four types of basal media viz., Murashige and Skoog's MS, Gamborg's B5, Nitsch and Nitsch, and White's W, supplemented with 1.0 mg/l 2,4 dichlorophenoxy acetic acid and 0.5 mg/l 6-benzylaminopurine and 40 g/l sucrose. MS basal medium, being more responsive for embryo induction, was used for further experimentation. To optimise the culture requirement MS basal medium was supplemented with 0.2-2.0 mg/l 2,4 dichlorophenoxy acetic acid and 0.5 and 1.0 mg/l 6-benzylaminopurine. The effect of cold pretreatment, hormone regime and sucrose concentration were tested for embryogenic efficiency. Genotype had a significant effect on the capacity of embryo induction. Addition of silver nitrate (2.5 mg/l), an ethylene inhibitor, stimulated embryo germination. Plantlets were obtained (10-15%) from embryos of only one genotype.
TL;DR: The photo-and thermooxidative degradation of different grades of high-impact polystyrene (HIPS) has been studied by FT-IR spectroscopy as discussed by the authors, where the oxidized films were treated with NH3 and SF, for the rapid identification and resolution of the various carbonyl species, alcohols, and hydroperoxides.
Abstract: SYNOPSIS The photo- and thermooxidative degradation of different grades of high-impact polystyrene (HIPS) has been studied by FT-IR spectroscopy. The oxidized films were treated with NH3 and SF, for the rapid identification and resolution of the various carbonyl species, alcohols, and hydroperoxides. All the sample gave similar oxidation products, but in varying quantities. The heterogenity in the film was also determined by micro-FT-IR spectroscopy. The thermal degradation processes at different temperature were compared. 0 1994 John Wiley & Sons, Inc.
TL;DR: A new moderately halophilic Micrococcus sp.
Abstract: A new moderately halophilic Micrococcus sp. 4, isolated from salt-pan water from India, produced extracellular amylase when cultivated aerobically in medium containing wheat bran, peptone, beef extract and sodium chloride. Other salts, such as sodium nitrate, potassium nitrate and sodium sulphate, were also found to be suitable for growth and enzyme production. Maximum amylase activity (1.2 IU ml-1) was secreted in the presence of 1 mol 1-1 sodium chloride. The enzyme requires the presence of either sodium chloride, potassium chloride, sodium nitrate, sodium citrate or sodium acetate for its activity. Maximum activity was found in the presence of 1 mol 1-1 sodium chloride. The pH and temperature optima for enzyme activity were 7.5 and 50°C, respectively.
TL;DR: In this article, Nanocrystalline alumina (Al 2 O 3 ) powder has been synthesized by the d.c. arc plasma method at atmospheric conditions using aluminium electrodes and X-ray diffraction and transmission electron microscopy confirmed the ultrafine nature of the particulates.
TL;DR: In this article, the packing density and gas permeability of a three-component copolymide series is presented. But, a conflicting result between free volume fraction and Gas permeability is observed, which may be due to a difference of the nature of free volume of each segment.
Abstract: Packing density and gas permeability of a three-component copolymide series is presented. The three-component polyimides are prepared a via “stepwise” synthesis procedure that goes through the acid anhydride terminated pre-polymer. The procedure ensures the statistical distribution of segments of the polymers. The polyimide series is composed of contrasting segments: a bulky and rigid hexafluoroisopropylidene-2,2-bis(phthalic acid anhydride)/9,9,-bis(4-aminophenyl)fluorene and a flexible hexafluoroisopropylidene-2-2-bis(phthalic acid anhydride)/2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane, with varying segment ratio. Generation of additional free volume by compolymerizing two segments is observed. The permeability of six pure gases—He, H2, N2, O2, CH4, and CO2—to the polymides showed positive deviation from the simple additivity rule of segment weight ratio reflecting the generation of free volume. However, a conflicting result between free volume fraction and gas permeability is observed, which may be due to a difference of the nature of free volume of each segment. © 1994 John Wiley & Sons, Inc.
TL;DR: An efficient synthesis of Epibatidine and its analogues via [3+2] cycloaddition of non-stabilised azomethine ylide and substituted 6-chloro-3-vinyl pyridine is reported.
TL;DR: In this paper, a single-step photocchemical approach for α-arylpropanoic acids (4 ) from α chloro-propiophenones (5 ) is described, which involves carbonyl triplet excited state directed 1,2-aryl migration of the aryl group.
TL;DR: In this article, the authors used NiCl2-H2O/PPh3 in the presence of inorganic base for the 4-bromo-4-hydroxyphenyl (4-BH)cinnamate and ethyl acrylate.
Abstract: The vinylation of 4-bromo-4′-hydroxybiphenyl and ethyl acrylate was studied using the catalyst NiCl2-H2O/PPh3 in the presence of inorganic base. Ethyl 4-(4′-hydroxyphenyl)cinnamate was formed as vinylation product with a selectivity as high as 98%. The effect of solvent, ligand and base for some halides was examined to show the applicability of the catalyst system.
TL;DR: The distribution of xylose isomerase as a function of growth in comparison with distributions of extra- and intracellular marker enzymes such as xylanase and beta-galactosidase revealed that xylOSE isomerases was truly secreted as an extracellular enzyme and was not released because of sporulation or lysis.
Abstract: An alkaliphilic, thermophilic Bacillus sp. (NCIM 59) produced extracellular xylose isomerase at pH 10 and 50°C by using xylose or wheat bran as the carbon source. The distribution of xylose isomerase as a function of growth in comparison with distributions of extra- and intracellular marker enzymes such as xylanase and β-galactosidase revealed that xylose isomerase was truly secreted as an extracellular enzyme and was not released because of sporulation or lysis. The enzyme was purified to homogeneity by ammonium sulfate precipitation followed by gel filtration, preparative polyacrylamide gel electrophoresis, and ion-exchange chromatography. The molecular weight of xylose isomerase was estimated to be 160,000 by gel filtration and 50,000 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, indicating the presence of three subunits. The enzyme is most active at pH 8.0 and with incubation at 85°C for 20 min. Divalent metal ions Mg2+, Co2+, and Mn2+ were required for maximum activity of the enzyme. The Km values for D-xylose and D-glucose at 80°C and pH 7.5 were 6.66 and 142 mM, respectively, while Kcat values were 2.3 × 102 s-1 and 0.5 × 102 s-1, respectively.
TL;DR: It is shown that 18-mer ODN containing spermine conjugated to 5-Me-dC at N4, form triplexes with complementary 24-mer duplex 8:9 at neutral pH (7.3, 100 mM NaCl), unlike the behavior of normal ODN's where optimal stability is at acidic pH (5.5).
TL;DR: In this paper, the authors investigated the effect of the bulky phthalide ring at the bridge carbon atom of bisphenol A-based polysulfone (PSF-PPHA).