Showing papers by "National Chemical Laboratory published in 1989"
TL;DR: The open-shell many-body perturbation theory (MBPT) and the propagator or the Green's function methods have now developed into vast computational technology, generating softwares that are cost-effective and competitive with the CI-based codes as mentioned in this paper.
Abstract: Publisher Summary This chapter discusses the developments of the open-shell many-body cluster expansion theories. Interpretation of most of the spectroscopic and dynamical phenomena, involving excited or ionized molecules and molecular fragments require models for open-shell states transcending the simple orbital description. The language of occupation number representation, coupled with the hole-particle description of the operators, the use of Wick's theorem and the attendant diagrammatic depiction of the various terms makes the many-body approach a very attractive alternative to the traditional CI-based theories. The open-shell many-body perturbation theory (MBPT) and the propagator or the Green's function methods have now developed into vast computational technology, generating softwares that are cost-effective and competitive with the CI-based codes. The cluster expansion based open-shell many-body formalisms possess even greater potentiality since they not only share and embed all the desirable features and technical advantages of the open-shell MBPT or propagator theories, but also are inherently non-perturbative in nature. They provide more compact descriptions of the electron correlation and are more flexible. Moreover, the cluster expansion of the open-shell functions provides valuable insight regarding the structure of general many-electron wave-functions.
337 citations
TL;DR: Alpha- and gamma-tocotrienols had inhibitory effects on lipid peroxidation of murine microsomes by adriamycin and growth inhibition of human and mouse tumor cells when the cells were exposed to these agents for 72 h in vitro, whereas tocopherol did not show any marked cytotoxic activity.
Abstract: Tocotrienols were evaluated for activity against transplantable murine tumors inoculated i.p. into mouse, and the activities of two tocotrienols and α-tocopherols were compared. When the compounds were injected i.p., α- and γ-tocotrienols were effective against sarcoma 180, Ehrlich carcinoma, and IMC carcinoma, and γ-tocotrienol showed a slight life-prolonging effect in mice with Meth A fibrosarcoma, but the tocotrienols had no antitumor activity against P388 leukemia at doses of 5-40 mg/kg/d. On the other hand α-tocopherol had only a slight effect against sarcoma 180 and IMC carcinoma. The antitumor activity of γ-tocotrienol was higher than that of α-tocotrienol. Tocotrienols showed growth inhibition of human and mouse tumor cells when the cells were exposed to these agents for 72h in vitro, whereas tocopherol did not show any marked cytotoxic activity. Alpha- and γ-tocotrienols had inhibitory effects on lipid peroxidation of murine microsomes by adriamycin.
128 citations
TL;DR: Glycolyse par l'ethylene-, le propene-and le diethyleneglycol de dechets de PET and polyesterification by l'acide adipique des diols oligomeres obtenus dans les conditions des procedes commerciaux, avec 2 plateaux de temperature as mentioned in this paper.
Abstract: Glycolyse par l'ethylene-, le propene- et le diethyleneglycol de dechets de PET et polyesterification par l'acide adipique des diols oligomeres obtenus dans les conditions des procedes commerciaux, avec 2 plateaux de temperature. La vitesse de la polyesterification du diol obtenu avec l'ethyleneglycol est la plus elevee
105 citations
TL;DR: The acidity of zeolite Beta has been characterized by FT i.r.d. spectroscopy and temperature-programmed desorption (t.p.d.) of NH 3 as discussed by the authors.
103 citations
TL;DR: In this article, the flux of trivalent rare earth ions (Sc3+, Y3+, La3+, Pr3+, Sm3+, Tb3+, Er3+ and Lu3+) across cellulose triacetate membranes containing a plasticizer was determined using benzoylacetone, dibenzoylmethane, and benzoy-l-, thenoyl- and furoyltrifluoracetone as carriers.
101 citations
TL;DR: A highly embryogenic culture of Eucalyptus citriodora was obtained by repetitive embryogenesis from somatic embryos cultured in the dark on a medium containing 500 mg/l each of glutamine and casein hydrolysate, 30 g/l of sucrose and 5 mg/L of 1-napthaleneacetic acid.
Abstract: A highly embryogenic culture ofEucalyptus citriodora was obtained by repetitive embryogenesis from somatic embryos cultured in the dark on a medium containing 500 mg/l each of glutamine and casein hydrolysate, 30 g/l of sucrose and 5 mg/l of 1-napthaleneacetic acid. Cultures retained morphogenetic ability for upto 36 months when maintained at 27°C by subculture at intervals of 4–5 weeks. The subculture period could be extended beyond 9 months if cultures were incubated at 10°C. On a hormone free medium incubated in light 50% of the embryos germinated to plantlets of which 70% survived when transferred to a sand and soil mixture.
92 citations
TL;DR: In this paper, an ensemble of travaux concernant la preparation and la caracterisation structurale de complexes du platine (II) and d'autres platinoides avec des nucleotides and avec l'ADN is presented.
91 citations
TL;DR: In situ nitrogen ion implantation of polycrystalline zirconium and titanium foils was performed and the surfaces were characterized by X-ray photoelectron spectroscopy (XPS) and ultraviolet photo-electron Spectrograph (UPS).
90 citations
TL;DR: M, verrucaria culture filtrate had 5-6 times more chitinase activity than commercial lytic enzyme preparations and this produced significantly higher levels of N-acetyl-D-glucosamine from the fungal mycelia preparations under study.
Abstract: Myrothecium verrucaria produced high levels of chitinases in a medium containing chitin used as a sole carbon source. Adding 0.03% urea increased the enzyme yield 4-fold in 7 days compared to the control. Adding oxgall (0.1%) to the growth medium gave the maximum activity (acid-swollen chitin-degrading activity, 2.0IU/ml) in 7 days. The biochemical characterization of the chitinase revealed its broader temperature (25-55°C) and pH (4.0-6.5) profiles of activity which showed its potential application in fungal mycelia degradation. Compared to commercial lytic enzyme preparations (NovoZym 234 and Onozuka R-10), M, verrucaria culture filtrate had 5-6 times more chitinase activity. And this produced significantly higher levels of N-acetyl-D-glucosamine from the fungal mycelia preparations under study.
88 citations
TL;DR: TGF‐β may be an important modulator of normal and leukemic hematopoietic cell growth and directly inhibited the growth of isolated Thy‐1‐positive progenitor cells.
Abstract: We have recently demonstrated that transforming growth factor (TGF)-beta 1 and TGF-beta 2 are potent inhibitors of the growth and differentiation of murine and human hematopoietic cells. The proliferation of primary unfractionated murine bone marrow by interleukin-3 (IL-3) and human bone marrow by IL-3 or granulocyte/macrophage colony-stimulating factor (GM-CSF) was inhibited by TGF-beta 1 and TGF-beta 2, while the proliferation of murine bone marrow by GM-CSF or murine and human marrow with G-CSF was not inhibited. Mouse and human hematopoietic colony formation was differentially affected by TGF-beta 1. In particular, CFU-GM, CFU-GEMM, BFU-E, and HPP-CFC, the most immature colonies, were inhibited by TGF-beta 1, whereas the more differentiated unipotent CFU-G, CFU-M, and CFU-E were not affected. TGF-beta 1 inhibited IL-3-induced growth of murine leukemic cell lines within 24 h, after which the cells were still viable. Subsequent removal of the TGF-beta 1 results in the resumption of normal growth. TGF-beta 1 inhibited the growth of factor-dependent NFS-60 cells in a dose-dependent manner in response to IL-3, GM-CSF, G-CSF, CSF-1, IL-4, or IL-6. TGF-beta 1 inhibited the growth of a variety of murine and human myeloid leukemias, while erythroid and macrophage leukemias were insensitive. Lymphoid leukemias, whose normal cellular counterparts were markedly inhibited by TGF-beta, were also resistant to TGF-beta 1 inhibition. These leukemic cells have no detectable TGF-beta 1 receptors on their cell surface. Last, TGF-beta 1 directly inhibited the growth of isolated Thy-1-positive progenitor cells. Thus, TGF-beta may be an important modulator of normal and leukemic hematopoietic cell growth.
81 citations
TL;DR: The shape selective catalytic properties of HZSM-22 and ZSM-23 in the isomerization of meta-xylene and methylation of toluene are compared with those of ZSM5 as discussed by the authors.
TL;DR: Plants of Arachis hypogea cultivar SB-11 are regenerated from immature zygotic embryo axis via direct somatic embryogenesis without an intermediate callus stage and 2,4-dichlorophenoxy acetic acid was essential for this response.
Abstract: We have regenerated plants of Arachis hypogea cultivar SB-11 from immature zygotic embryo axis via direct somatic embryogenesis without an intermediate callus stage. Induction and maturation of the somatic embryos was achieved on the same medium. 2,4-dichlorophenoxy acetic acid (2,4-D) was essential for this response. Both the size of the immature zygotic embryo axis and the concentration of 2,4-D were important for direct somatic embryogenesis. Embryos germinated in hormone free medium, and plants survived in a sand:soil mixture.
TL;DR: In this article, the enthalpy of perovskite compounds, ΔfH° (ABO3, B = transition metais), from binary oxides can be well characterized in terms of the tolerance factor, t≡(rA+ ro)√2 (rB+ ro), where rA and rB are the radii of A-site ions with 12-coordination and B-site ion with 6-coordinations, respectively, and Δ fH°=−168 + 270(1 − t) kJ·mol
Abstract: It has been found that the enthalpy of formation of perovskite compounds, ΔfH° (ABO3, B = transition metais), from binary oxides can be well characterized in terms the tolerance factor, t≡(rA+ ro)√2 (rB+ ro), where rA and rB are the radii of A-site ions with 12-coordination and B-site ions with 6-coordination, respectively, and ΔfH°=−168 + 270(1 − t) kJ·mol−1 for AIBVO3, ΔfH°=−125 + 1000(1 − t) kJ·mol−1 for AIIBIVO3, and ΔfH°=− 90 + 720(1 − t) kJ·mol−1 for AIIIBIIIO3. Although the thermodynamic data of K2NiF4 compounds are not extensive, a similar regularity can be found when use is made of the radii of A-site ions with 9-coordination for the K2NiF4 compounds. These correlations will be quite useful in predicting.
TL;DR: Xylan completely protected the enzyme from inactivation by the above reagents, suggesting the presence of tryptophan and cysteine at the substrate-binding site.
Abstract: Extracellular xylanase produced in submerged culture by a thermotolerant Streptomyces T7 growing at 37-50 degrees C was purified to homogeneity by chromatography on DEAE-cellulose and gel filtration on Sephadex G-50. The purified enzyme has an Mr of 20,463 and a pI of 7.8. The pH and temperature optima for the activity were 4.5-5.5 and 60 degrees C respectively. The enzyme retained 100% of its original activity on incubation at pH 5.0 for 6 days at 50 degrees C and for 11 days at 37 degrees C. The Km and Vmax. values, as determined with soluble larch-wood xylan, were 10 mg/ml and 7.6 x 10(3) mumol/min per mg of enzyme respectively. The xylanase was devoid of cellulase activity. It was completely inhibited by Hg2+ (2 x 10(-6) M). The enzyme degraded xylan, producing xylobiose, xylo-oligosaccharides and a small amount of xylose as end products, indicating that it is an endoxylanase. Chemical modification of xylanase with N-bromosuccinimide, 2-hydroxy-5-nitrobenzyl bromide and p-hydroxymercuribenzoate (PHMB) revealed that 1 mol each of tryptophan and cysteine per mol of enzyme were essential for the activity. Xylan completely protected the enzyme from inactivation by the above reagents, suggesting the presence of tryptophan and cysteine at the substrate-binding site. Inactivation of xylanase by PHMB could be restored by cysteine.
TL;DR: Alkyl-substituted p-benzoquinones were easily synthesized in good yields by the oxidation of the corresponding phenols with a hydrogen peroxide/heteropolyacid couple in acetic acid as discussed by the authors.
TL;DR: In this article, the authors show that the formation of alcohols may be related to the presence of bridged-CO species on the surface of the catalysts, and they show that Co2(CO)2 supported on SiO2 changes to Co4(CO), and then to highly dispersed cobalt metal when heated in a stream of hydrogen at 673 K.
TL;DR: In this paper, a super-high-pressure mercury lamp through the Pyrex glass wall of a cell was used to degrade chloral hydrate in the presence of suspended TiO2.
Abstract: Chloral hydrate was degraded in the presence of suspended TiO2 by illumination with a super-high-pressure mercury lamp through the Pyrex glass wall of a cell. The addition of H2O2 enhanced the degradation rate 3.4 times. The degradation rate increases with pH in the absence of H2O2 and exhibits a maximum at pH 5.5 in the presence of H2O2. Of the semiconductors tested ZnO was the most efficient catalyst. The effect of H2O2 was observed only with TiO2 and WO3.
TL;DR: In this paper, a chemical potential diagram for A-B-O (A, B = metallic elements) systems has been constructed to make visually clear the thermodynamic stability of double oxides.
Abstract: A chemical potential diagram for A-B-O (A, B = metallic elements) systems has been constructed to make visually clear the thermodynamic stability of double oxides; the stability area of metallic elements, their binary oxides, and double oxides can be presented as convex polygons in a log (aA/aB) vs log P(O2) plot, a and P(O2) being the activity of metallic elements and the oxygen partial pressure, respectively; the axis variable, log (aA/aB), is used to treat two metallic elements equivalently. The Co-Ti-O and La-Co-O systems have been chosen as examples to demonstrate how the present diagram can provide complicated phase relations in a compact and visualized manner. An attempt has also been made to utilize this diagram to present graphically products of kinetic decomposition of double oxides placed in an oxygen potential gradient.
TL;DR: In this paper, the rotational spectra of the 79Br and 81Br isotopic species of gaseous hypobromous acid, HOBr and DOBr, as well the v3 = 1 excited state of HOBr have been observed and analyzed.
TL;DR: The catalytic properties of zeolite β in the isomerization of metaxylene, and the methylation and disproportionation of toluene have been measured and compared with those of other zeolites like ZSM-5, -23, -48, and -50 as mentioned in this paper.
TL;DR: In this paper, it was shown that the apparent absence of the so-called inverted region in the free energy dependence of electron transfer rates is not accounted for by the dielectric saturation effect.
TL;DR: Stereoselective ∝-glycosylations may be achieved using stable 2-pyridyl thioglycosides (anomeric mixture) having a non-participating 2-substituent as glycosyl donor and methyl iodide as an activator.
TL;DR: A coupled-cluster method for the calculation of the response of properties of a system of various orders using a multiconfigurational model space thus making it suitable for open-shell or quasidegenerate situations.
Abstract: We present in this paper a coupled-cluster method for the calculation of the response of properties of a system of various orders. This uses a multiconfigurational model space thus making it suitable for open-shell or quasidegenerate situations. We present the basic equations and the hierarchy for generating higher-order response.
TL;DR: In this paper, a shuttlecock-shuttlebox model for a sorbate-zeolite channel system is proposed to explain for sorbates molecules the importance of configuration and flexibility over size in sorption/diffusion in zeolites.
TL;DR: Silica-supported cobalt catalysts doubly modified with ruthenium and alkaline earths were active for the synthesis of C2-oxygenates (C2 O) from syngas as mentioned in this paper.
TL;DR: Amorphous carbon films have been deposited on silicon and quartz substrates by pulsed ruby laser vaporization from pyrolytic graphite, and the properties of the deposited carbon films were studied using IR and UV-VIS transmission, ellipsometry, and laser-Raman spectroscopies as mentioned in this paper.
Abstract: Amorphous carbon films have been deposited on silicon 〈111〉 and quartz substrates by pulsed ruby laser vaporization from pyrolytic graphite. Depositions have been carried out at different substrate temperatures, and the properties of the deposited carbon films have been studied using IR and UV–VIS transmission, ellipsometry, and laser-Raman spectroscopies. Chemical and electrical resistivity measurements have also been performed. It is shown that the film properties depend critically on the substrate temperature and that at the substrate temperature of 50 °C films with substantial proportion of sp
3 hybridized orbitals are obtained.
TL;DR: Yeast mutant strains which secrete large amounts of human lysozyme were screened using an agar medium containing bacterial cells and it was found that the protease deficiency was caused by a deficiency in conversion of proenzyme to mature enzyme in ssl1 mutant cells.
Abstract: Yeast mutant strains which secrete large amounts of human lysozyme were screened using an agar medium containing bacterial cells. Nine mutants secreted over 10 times more lysozyme than the wild-type parent strain. The mRNA levels for lysozyme in the mutants were not higher than that of the wild-type strain. Three of the mutant strains were deficient in carboxypeptidase Y activity. It was found that the protease deficiency was caused by a deficiency in conversion of proenzyme to mature enzyme in ssl1 mutant cells. The ssl1 gene was found to be closely linked to the centromere and determine both the efficiency of secretion of lysozyme and the processing of carboxypeptidase Y.
TL;DR: In this paper, 2,3,6-trimethylphenol was efficiently oxygenated to trimethyl-p -benzoquinone by molecular oxygen in the presence of catalytic amount of copper (II) chloride/amine hydrochloride in alcoholic solvent at ambient temperature.
TL;DR: In this paper, an amphiphilic charge transfer complex with azobenzene introduced as a switching unit into the hydrophobic part was synthesized, which increased the conductivity of the Langmuir-Blodgett (LB) film.
TL;DR: In this article, conductive Langmuir-Blodgett (LB) films of alkylammonium-metal(dmit) 2 (where H 2 dmit ≡ 4,5-dimercapto-1,3-dithiol-2-thione) system are described.