Showing papers by "National Chemical Laboratory published in 1984"
TL;DR: The interfering effect ofbeta-glucosidase, which acts on both agluconic and holosidic bonds, is overcome by the addition of D-glucono-1,5-delta-lactone, a specific inhibitor of beta-glUCosidases.
305 citations
TL;DR: In this article, photoelectron-spectroscopic studies (XPS and UPS) have been carried out to investigate electronic structure and chemical bonding in the monoselenides of nickel, manganese and cobalt.
167 citations
TL;DR: In this article, a review on drag reduction has been presented in order to bring out some important aspects of the drag reduction phenomenon and its potential for practical use, which is biased towards micellar systems.
Abstract: A state-of-the-art review on drag reduction has been presented in order to bring out some important aspects of the drag reduction phenomenon and its potential for practical use. The review is biased towards micellar systems and discusses in detail the morphological differences between drag reducing polymeric and micellar systems. Work relating to polymeric systems has not been dealt in detail as it has been the subject of earlier reviews. Studies relating to biological additives as well as suspensions have been briefly mentioned without detailed discussion as their potential for practical use presently appears] to be limited.
97 citations
TL;DR: Two xylanases showed activity toward carboxymethyl cellulose but no activity toward para-nitrophenyl-beta-d-xyloside or laminarin, whereas xylanase II was inactive, indicating that they are endoxylanases capable of hydrolyzing 1,3-alpha-l-arabinofuranosyl branch points.
Abstract: Neurospora crassa 870 produced 14 and 0.025 U of extracellular xylanase (1,4-beta-d-xylan xylanohydrolase; EC 3.2.1.8) and beta-xylosidase (1,4-beta-xylan xylohydrolase; EC 3.2.1.37) per ml, respectively, in 4 days when commercial xylan was used as a carbon source. The effects of pH and carbon sources on xylanase production by N. crassa are discussed. Two xylanases (I and II) were purified and had pI values of 4.8 and 4.5 and molecular weights of 33,000 and 30,000. The maximum degree of hydrolysis of xylan by the extracellular culture broth was 66% in 4 h. The end products of xylan hydrolysis by xylanase I and II showed the presence of xylose, xylobiose, xylotriose, xylotetraose, xylopentose, and arabinose, indicating that they are endoxylanases capable of hydrolyzing 1,3-alpha-l-arabinofuranosyl branch points. Both xylanases showed activity toward carboxymethyl cellulose but no activity toward para-nitrophenyl-beta-d-xyloside or laminarin. Xylanase I showed appreciable activity toward para-nitrophenyl-beta-d-glucoside, whereas xylanase II was inactive.
90 citations
TL;DR: In this article, it was found that Pt/γ-alumina catalyst was effective for the decomposition of hydrogen iodide over platinum supported γ alumina, and an overall rate equation was obtained based on the Langmuir-Hinshelwood model.
68 citations
TL;DR: In this article, a comprehensive mathematical model for the finishing stages of polyethylene terephthalate (PET) synthesis is developed, which takes into account the variables which have significant influences on polymerization but have not been hitherto taken into account, eg, changing interfacial concentration and the presence of side reactions.
Abstract: A comprehensive mathematical model for the finishing stages of polyethylene terephthalate (PET) synthesis is developed The model takes into account the variables which have significant influences on polymerization but have not been hitherto taken into account, eg, changing interfacial concentration and the presence of side reactions The model is applicable to industrial polymerizations, and the predictions agree well with the literature and with certain pilot-plant and commercial data
57 citations
TL;DR: Explants from stem, leaf and rachilla of mature coconut trees turned green and swelled on Y3 semi-solid basal media supplemented with 2,4-D, K, NAA, BA and activated charcoal.
Abstract: Complete plants were grown from zygotic embryos cultured on Y3 basal liquid medium supplemented with coconut milk, BA and NAA. Explants from stem, leaf and rachilla of mature coconut trees turned green and swelled on Y3 semi-solid basal media supplemented with 2,4-D, K, NAA, BA and activated charcoal. Callus was initiated in explants from the subapical regions of the stem on Y3 basal medium supplemented with 2,4-D (4.52×102μM). Globular embryo-like structures were obtained when this callus was subcultured to auxinless medium. Root formation was obtained from leaf explants on Y3 basal medium containing citric acid, ascorbic acid and 2,4-D (4.52×102 μM). Globular embryo-like structures were also obtained directly from leaf explants on a Y3 basal medium supplemented with 2,4-D (2.26×102 μM). Callus isolated from rachilla explants on Y3 basal medium containing 2,4-D(4.52×102 μM), formed nodular structures when transferred to medium with 2,4-D (2.3×101 μM). These nodules developed roots from the base of the nodular growth whereas from the upper portion shoots were observed on Y3 basal liquid medium.
56 citations
TL;DR: In this article, the half-life of methyleneimine was calculated to be about 10 min, which is much longer than the previously reported values, 0.1 or 10 sec.
51 citations
TL;DR: The extent of aromatization and the distribution of aromatics in the conversions of methanol, ethanol, ethylene, propylene, butene-1, 1-hexene and cyclohexene on HZSM-5 zeolite are found to depend strongly on the extent of catalyst poisoning with pyridine, which causes not only a decrease in the stronger sites available for the reactions, but also leads to an increase in the diffusional resistance to the reaction species and the deactivation due to the deposition of hydrocarbon residues in the Zeolite channels as mentioned in this paper
49 citations
48 citations
TL;DR: In this paper, the infrared absorption spectrum of allylimine in the gas phase was measured for the first time and the spectrum consisted of two rotational isomers, cis and trans, around the CC bond.
TL;DR: In this article, a quantitative procedure for identifying critical operating conditions and material properties for the melt spinning of poly(ethylene terephthalate) (PET) is considered, based on the experimental observation that for vitrified polymers like polystyrene and PET spun at speeds below 3000 m/minute, the molecular orientation of the as-spun fiber is uniquely determined by σ L, the spinline stress at the glass transition temperature.
Abstract: A quantitative procedure for identifying critical operating conditions and material properties for the melt spinning of poly(ethylene terephthalate) (PET) is considered. The method is based on the experimental observation that for vitrified polymers like polystyrene and PET spun at speeds below 3000 m/minute, the molecular orientation of the as-spun fiber is uniquely determined by σ L, the spinline stress at the glass transition temperature. Using a constant tension model that predicts σL, a sensitivity analysis of the fiber orientation to changes in process variables is investigated. Extrusion temperature, melt intrinsic viscosity, feed rate, and the takeup velocity are the key variables for PET melt spinning, as they strongly affect the freeze line location and the as-spun fiber orientation.
TL;DR: In this paper, the authors analyzed the catalytic decomposition of HI by using a microporous membrane under reaction and showed that the conversion rate rises more than the equilibrium value.
TL;DR: In this article, the effects of the structure of the substrates, the diphosphine/Pd ratio, the CO pressure up to 800 kg cm−2, the R in ROH (alcohol), the solvent, and additives such as organic bases, halide salts and hydrogen have been investigated mainly for 2-phenylpropene.
TL;DR: Multiple shoot formation was induced from excised leaf explants of Annona squamosa Linn on a Murashige and Skoog basal medium containing benzylaminopurine and kinetin and the process of development of adventitious buds in leaf culture was analysed histologically.
Abstract: Multiple shoot formation was induced from excised leaf explants of Annona squamosa Linn. (custard apple) seedlings on a Murashige and Skoog basal medium containing benzylaminopurine and kinetin. Various auxins in combination with the above medium produced callusing of the explants. In an investigation of environmental factors affecting shoot induction it was seen that the maximum number of shoots were obtained using the leaf base with petiole at a temperature of 27°C and a light intensity of 1000 lux. Roots were initiated erratically when individual shoots were treated with an auxin and then transferred to an auxin free medium. The process of the development of adventitious buds in leaf culture was analysed histologically.
TL;DR: In this paper, it was revealed that the unknown phase is another polymorph of Mg 2 Ni hydride which is easily transformed into the low temperature form by grinding the powder in a mortar at room temperature.
Abstract: The high temperature form of Mg 2 Ni hydride has an f.c.c. lattice with the metal atoms occupying antifluorite positions. It transforms to the low temperature form at 235°C. In earlier work the structure of the low temperature form was determined from its X-ray powder diffraction data. It can be described as a monoclinic distortion of the high temperature cubic lattice. However, the low temperature phase is usually contaminated with a small amount of an unknown phase which shows a similar powder pattern to the high temperature form. In the present investigation it was revealed that this unknown phase is another polymorph of Mg 2 Ni hydride which is easily transformed into the low temperature form by grinding the powder in a mortar at room temperature. This intermediate phase was found to be stabilized by substituting cobalt for 10 wt.% Ni. This structure can also be described as a distortion of the high temperature cubic lattice and the main peaks were indexed with an orthorhombic cell with a = 6.572 A , b = 4.520 A and c = 4.560 A . However, the presence of several weak peaks indicates that longer-range ordering exists and that the true unit cell is larger than this.
TL;DR: In this article, polyimides were synthesized from pyromellitic dianhydride (PMDA), 3,3′,4,4′-benzophenone tetracarboxylic dianhydrate (BTDA), and three different diamines with the following general structure: ======¯¯¯¯¯¯where R is ethyl, propyl, or isobutyl.
Abstract: Polyimides were synthesized from pyromellitic dianhydride (PMDA), 3,3′,4,4′-benzophenone tetracarboxylic dianhydride (BTDA), and three different diamines with the following general structure:
where R is ethyl, propyl, or isobutyl. The poly(amic acids) obtained had inherent viscosities ranging from 0.30 to 0.93 and were thermally/chemically converted to polyimides. The thermal stability of the polyimides was evaluated by using dynamic thermogravimetric analysis in air. Physical and thermal properties of these polyimides were compared with that obtained by reacting 2,2-bis(4-aminophenyl) propane and PMDA/BTDA.
TL;DR: In this article, a unitary coupled cluster method is advocated for the calculation of static properties, and a suitable unitary wave function is envisaged for the perturbed Hamiltonian H(λ) including the relevant static property.
Abstract: A unitary coupled cluster method is advocated in this paper for the calculation of static properties. Corresponding to the perturbed Hamiltonian H(λ) including the relevant static property, a suitable unitary wavefunction is envisaged. It is shown that a specific nonvariational model of calculating various order static properties utilising this unitary ansatz results in simplifications compared to the previous Coupled Cluster Theories using only hole-particle excitation parameters formulated for this purpose.
TL;DR: In this article, the acid strength distribution and catalytic behavior of HZSM5 zeolites with varying SiO2/A1203 ratios (in the range 30 - 800) and hydrothermally treated at different temperatures have been studied.
TL;DR: In this paper, the Co2(CO)8-1,2-bis (diphenylphosphino)ethane (dpe) system under CO/H2O and CO/C2 is discussed.
TL;DR: It is of interest that the percent saccharification of cellulosic substrates with the Penicillium enzyme is comparable to that of T. reesei cellulase when the same amount of filter paper activity is used, although the endo-glucanase activity of the latter is two to three times higher.
Abstract: Enzymatic hydrolysis of cellulose is a promising method for the conversion of waste cellulose to glucose During the past few years, the development of this technology has proceeded rapidly, with significant advances made in enzyme production, pretreatment, and hydrolysis A variety of fungi are reported to produce cellulases but among these Trichoderma reesei and its mutants are powerful producers of cellulases However, the search for new and possibly better sources of cellulase is continued due to the low levels of beta-glucosidase of T reesei Penicillium funiculosum produces a complete cellulase having endo-beta-1,4-glucanase (15-20 U/mL), exo-beta-1,4-glucanase (15-20 U/mL), and high beta-glucosidase (8-10 U/mL) The saccharification of alkali-treated cotton and bagasse by P funiculosum enzyme was 70 and 63%, respectively It was possible to obtain glucose concentration as high as 30% using 50% bagasse It is of interest that the percent saccharification of cellulosic substrates with the Penicillium enzyme is comparable to that of T reesei cellulase when the same amount of filter paper activity is used, although the endo-glucanase activity of the latter is two to three times higher This communication reports the studies on saccharification of lignocelluloses by P funiculosum cellulase and certain studies on the kinetic aspects (Refs 15)
TL;DR: The crystal and molecular structure of the first peralkylcyclotrisilane, [(t-BuCH 2 Si] 3, have been determined by X-ray diffraction.
TL;DR: Using a coupled cluster form of the wave function, a variational method is formulated for calculation of static properties of any order in this article, and a size consistent functional is set up.
Abstract: Using a coupled cluster form of the wave function, a variational method is formulated for calculation of static properties of any order. Corresponding to an appropriate perturbed hamiltonian H(λ) including the relevant static property, a size consistent functional is set up. In a hierarchical fashion, properties of different orders may be found out using a variational method.
TL;DR: The ability of metal carbonyls to cleave the PC bonds was found to be Rh > Co > Ru in the presence of a rhodium, ruthenium, or cobalt carbonyl as discussed by the authors.
TL;DR: Three purified endo-(1→4)-β- d -glucanases from Sclerotium rolfsii culture filtrates showed homogeneity in disc-gel electrophoresis and in analytical isoelectric-focusing in polyacrylamide gel, but they showed some differences in the mode of attack on cellodextrins, phosphoric acid-swollen cellulose, and lichenan.
TL;DR: In this paper, the effect of ligands, metal oxide and chloride promoters on the conversion of 2,4-dinitrotoluene (DNT) and selectivity of isocyanates has been investigated.
TL;DR: In this paper, the isotropic Raman linewidth of t-butanol at 753 cm −1 has been measured in aqueous solution and in cyclohexane solution.
TL;DR: In this paper, a thermal decomposition of metal alkoxides is used for the preparation of stabilized zirconia, which is shown to be purely an oxygen ion conductor.
Abstract: The preparation of stabilized zirconia by thermal decomposition of metal alkoxides is reported. Formation of stabilized zirconia takes place at 400° C. The a.c. conductivity of the samples has been measured from 400 to 1000°C. The best conductivity is found in ZrO2doped with 15 per cent CaO, which at 400° C is 2.37×10−6 Ω−1 cm−1 and at 1000°C is 1.26×10−2 Ω−1 cm−1, with an activation energy of 1.16eV. Transport number measurements show that stabilized zirconia prepared by this method is purely an oxygen ion conductor.
TL;DR: Sharpless kinetic asymmetric epoxidation on (±)-2-(l-hydroxyethyl)-5,8-dimethoxy-3,4-dihydronaphthalene (8) followed by LAH reduction gave R-2-(S-lh-hydroxethyl)-2hydroxy-5, 8-dimethyl-1,2, 3, 4-tetrahydronophthalene and the undesired antipode as discussed by the authors.