Showing papers by "National Chemical Laboratory published in 1980"
TL;DR: It is estimated that by subculture 500 viable plants can be obtained from a single bud of a mature plant or 3000 plants from a seedling in a year.
143 citations
TL;DR: A general theoretical analysis for predicting the overall rate of reaction in a slurry catalytic as discussed by the authors for various kinetics is presented, incorporating all the transport effects, and major correlations and methods for determining gas-liquid and liquid-solid mass transfer coefficients and effective diffusivity in liquid filled pores are reviewed.
Abstract: This article reviews the major developments in the engineering and design of three-phase slurry catalytic reactors. A general theoretical analysis for predicting the overall rate of reaction in a slurry reactor for various kinetics is presented, incorporating all the transport effects. Modeling of semi-batch reactors is discussed and design procedures are indicated. Some major correlations and methods for determining gas-liquid and liquid-solid mass transfer coefficients and effective diffusivity in liquid filled pores are reviewed. Slurry reactors are compared with other three-phase reactors, such as trickle bed or packed bed reactors, and relative merits are pointed out.
119 citations
TL;DR: In this article, an equation for the correction of the finite slit width effect on line widths of Lorentzian Raman lines is derived for up to S/δa = 0.7, more applicable than those proposed previously.
83 citations
TL;DR: Glutaraldehyde crosslinking decreases immuno-globulin G leakage from Sepharose-immunoadsorbents to undetectable levels without noticeably affecting antigen-binding activity and reduces leakage of lactoperoxidase from solid-phase lactoperxidase with only a moderate reduction of enzymatic activity.
82 citations
TL;DR: In this article, the authors describe the behavior of a packed-bed nuclear reaction unit with respect to the nature of the reaction scheme and its sensitivity to perturbations in operating conditions, and describe a variety of models ranging from simple one-dimensional pseudohomogeneous to two-dimensional heterogeneous.
Abstract: Packed bed reactors are commonly used for carrying out heterogeneous chemical reactions, and the attendant complexities arising out of the interactions of the momentum, heat, and mass transport processes make the design of such units a very involved and cumbersome task. The strategy for rational design depends strongly on the nature of the reaction scheme and its sensitivity to perturbations in operating conditions. Models ranging from simple one-dimensional pseudohomogeneous to two-dimensional heterogeneous are used to describe process behavior. Reviews detailing these aspects of the packed-bed have appeared from time to time.
82 citations
TL;DR: Two isoprenylated benzophenone derivatives of Garcinia cambogia have been isolated from the latex of the plant and the structure of the derivatives has been deduced.
77 citations
TL;DR: In this article, a plateau region was observed between a body-centred tetragonal phase Ti 0.2 V 0.8 −H 2 and an f.c.d. phase Ti 1.8 H ≈ 0.6.
Abstract: Pressure-composition isotherms were measured for the Ti 0.2 V 0.8 −H 2 and Ti 0.4 V 0.6 −H 2 systems at temperatures between 80 and 150°C and pressures below 100 kgf cm −2 the hydride phases formed were identified by X-ray diffraction. In the Ti 0.2 V 0.8 −H 2 system, a plateau region was observed between a body-centred tetragonal phase Ti 0.2 V 0.8 H ≈0.8 and an f.c.c. phase Ti 0.2 V 0.8 H ≈1.6 . These hydride phases correspond to the monohydride and the dihydride of the V−H 2 system. In the Ti 0.4 V 0.6 −H 2 system, the transformation between the two hydride phases was found to be irreversible and the higher hydride did not decompose under the experimental conditions used.
76 citations
TL;DR: In this paper, the kinetics of diffusion-controlled reaction between molecules which are confined in a micelle is formulated and applied to recent experiments on luminescence quenching and excimer formation in micelles.
55 citations
TL;DR: In this article, a drastic change of frequency in the totally symmetric stretching vibration (v1) for the Ln(H2O)3+n ions (Ln3+ = rare earth ion) is observed between Sm and Gd and is interpreted as evidence for a change in the inner-sphere hydration number of rare earth ions in the series.
51 citations
TL;DR: In this paper, two experimental apparatuses based on a steady state method and a non-steady state method were constructed for measuring the effective thermal conductivity of metal hydrides.
Abstract: Two experimental apparatuses — one based on a steady state method and the other based on a non-steady state method — were constructed for measuring the effective thermal conductivity of metal hydrides. The experimental and analytical procedures for the steady state method are described in detail and data are presented for the TiMn1.5 hydride as a function of hydrogen gas pressure, temperature and hydride composition.
50 citations
TL;DR: In official assays of the tar and nicotine yields of 12 popular brands of cigarettes, smoking machines took fewer puffs in 1974 than in 1969, and the decline in puffs appears to have been a major cause of the reported reductions in tar and Nicotine yields.
Abstract: In official assays of the tar and nicotine yields of 12 popular brands of cigarettes, smoking machines took fewer puffs, on the average, in 1974 than in 1969. The decline in puffs appears to have been a major cause of the reported reductions in tar and nicotine yields during this period.
TL;DR: In this article, the microwave spectra of eight isotopic species of COCl2 have been observed, and the following rotational constants have been obtained: an analysis of the rotational constant has resulted in the rs and rm structures.
TL;DR: In this paper, the unresolved Stark patterns of the b -type transitions are analyzed by the use of computer simulation, including second-order perturbation theory, including the effect of spin-doublings in the denominators, is used for the calculation of the Stark effect coefficients.
TL;DR: In this article, it was shown that the detection and characterization of weak low frequency Raman bands in aqueous solutions is much easier in the Raman spectrum for the glassy state than for the liquid state.
Abstract: Raman spectra of aqueous zinc halide solutions are obtained in both liquid and glassy states. It is shown that the detection and characterization of weak low frequency Raman bands in aqueous solutions is much easier in the Raman spectrum for the glassy state than for the liquid state. Comparison of the spectra shows that the tetrahedral ZnX ions are the most stable ionic entities in the glassy state.
TL;DR: Sclerotium rolfsii UV-8 mutant secretes high levels of cellobiase and xylanase in addition to having high cellulase production, and the addition of 2% corn steep liquor to NM-2 medium increased endo-beta-glucanase, cellobiases, and x Dylanase yields by approximately 1.5-fold.
Abstract: Sclerotium rolfsii UV-8 mutant secretes high levels of cellobiase and xylanase in addition to having high cellulase production The apparent K(m) and V(max) of cellobiase (grown in NM-2 + 2% corn steep liquor medium) with cellobiose as a substrate were 56 mM and 222 mumol of glucose liberated per min per ml of culture filtrate, respectively The addition of 2% corn steep liquor to NM-2 medium increased endo-beta-glucanase, cellobiase, and xylanase yields by approximately 15-fold
TL;DR: In this article, six ω-hydroxy acids were converted to macrocyclic lactones by treatment with cyanuric chloride and triethylamine in acetone at room temperature.
TL;DR: Theoretical diffusion constants were computed for each solution, on the basis of the Hynes-Kapral-Weinberg model as mentioned in this paper, and it is suggested that intermolecular association of benzene with some solvent molecules is not so strong as to affect significantly the rotational motion.
Abstract: Raman line widths of v 1 and v 15 of benzene were measured in a number of solvents, and rotational diffusion constants were determined. Experimental Dz as well as Dx showed the solvent dependence. Theoretical diffusion constants were computed for each solution, on the basis of the Hynes-Kapral-Weinberg model. The theory well explains the solvent dependence of experimental diffusion constants, and it is suggested that intermolecular association of benzene with some solvent molecules is not so strong as to affect significantly the rotational motion of benzene.
TL;DR: In this paper, the vibrational relaxation widths of the i.r. raman and i. r. a 1 bands of acetonitrile, CH 3 CN and CD 3 CN, have been measured in the pure liquid and in solutions of isotopic compounds.
TL;DR: Tributyltin cyanide was used as an efficient cyanation agent for acyl chlorides to give acyl cyanides in excellent yields as mentioned in this paper, and was found to be an efficient acidification agent for chlorides.
TL;DR: In this article, the effect of small amounts of low molecular weight polypropylene oxide on the rheological properties of talc-filled poly-propylene composites was studied experimentally using a capillary viscometer.
Abstract: The effect of small amounts of low molecular weight polypropylene oxide on the rheological properties of talc-filled polypropylene composites was studied experimentally using a capillary viscometer. The elastic behavior of the system was investigated by exit pressure and die swell methods. Initial studies showed that the talc filler does not influence the viscosity of the polypropylene but decreases the elasticity of the polymer system. Addition of oligomer concentration in a 40 wt percent talc-filled polypropylene not only decreases the viscosity but also further decreases considerably the elasticity of the filled polymer composite. In both cases about 3 wt percent oligomer cone entration appears to be optimal, and further addition of oligomer does not significantly influence the rheological characteristics of the talc-filled polypropylene composite.
TL;DR: A first-order deactivation model which includes a step that does not destroy enzyme activity, but is a compulsory precursor of the step that did, is shown to fit reasonably well the immobilized and soluble enzyme deactivation data presented.
Abstract: A first-order deactivation model which includes a step that does not destroy enzyme activity, but is a compulsory precursor of the step that does, is shown to fit reasonably well the immobilized and soluble enzyme deactivation data presented. The deactivation rate coefficient increases with time, and the model may be generalized to include n such compulsory precursors.
TL;DR: In this paper, three different diisocyanates with the following general structure were synthesized: ethyl, propyl, or phenyl, where R is ethyl or propyl.
Abstract: Polyimides soluble in polar solvents such as dimethylacetamide (DMAC) and dimethylformamide (DMF) were synthesized by reacting 3,3′,4,4′-benzophenonetetracarboxylic dianhydride (BTDA) and three different diisocyanates with the following general structure:
where R is ethyl, propyl, or phenyl. Thermal properties of these polymides have been compared with that obtained by reacting 2,2-bis(4-isocyanatophenyl)propane and BTDA.
TL;DR: In this paper, the Raman spectra of glassy aqueous LiX and CaX2 solutions were obtained in the low frequency region (10−900 cm−1) and two low frequency Raman bands were clearly observed.
TL;DR: Four isoinhibitors of plant thiol proteinases from seeds of the legume Vigna unguiculata subsp.
TL;DR: A new and simple synthesis of 4-demethoxy-7-deoxydaunomycinone has been carried out in this paper essentially in three steps starting from 1,4-dimethyl-6-tetralone.
TL;DR: In this article, the T ← So absorption spectra of a p-terphenyl (TP) crystal at 77 K and room temperature were measured and compared with the T − So absorption and phosphorescence spectra in solution, giving some information about the potential curves of TP molecules as a function of the angle between the outer and central benzene rings both in the triplet and ground state.
TL;DR: In this paper, the theoretical Raman linewidths of cyclohexane-d 12 were calculated on the basis of the dephasing model, and fitted to the experimental results by adjusting the collision diameters of the solvent molecules.
Abstract: Raman linewidths of v 2 at 2083 cm-1 of cyclohexane-d 12 were measured in 40 solvents. The theoretical linewidths, calculated on the basis of the dephasing model, have been fitted to the experimental linewidths by adjusting the collision diameters of the solvent molecules. Most of the diameters thus determined are in good agreement with literature values, which indicates that the present model of the vibrational dephasing explains well the solvent dependence of Raman linewidths.
TL;DR: In this paper, the microwave spectrum of CH 3 OD has been observed in the frequency region between 14 and 92 GHz and rotational, torsional, and torsion-vibration-rotation interaction constants have been evaluated.
TL;DR: The temperature dependence of the UV absorption spectrum indicates that a displacive transition occurs rather than an order-disorder one in a TP crystal as discussed by the authors, and the UV spectrum shifts to higher energy as the temperature falls.
TL;DR: In this paper, 2-R1-4′-R-4-(4-nalkoxybenzoyloxy)azobenzenes, where R = n-butyl, methyl and methoxy, R1 = H and methyl and n-alkoxy, ethoxy and nbutoxy were synthesized, were used as stationary phases for the separation of di- and trisubstituted benzene.