Liquid suction by porous ceramic materials
Mise au point d'un appareillage et d'une methode pour la mesure de la sorptivite des ceramiques poreuses
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Highly stereoselective hydrogen transfer from alcohols to carbonyl compounds catalysed by aluminium porphyrins
Aluminium porphyrins, such as chloroaluminium porphyrin, catalyse a novel hydrogen transfer process in the reduction of aldehydes or ketones with alcohols, and the reactions eventually proceed with very high stereoselectivities.
Computer simulation of a 360° field-of-view ‘‘top-hat’’ electrostatic analyzer
Via computer simulation, we have studied the characteristics of the ‘‘top-hat’’ electrostatic analyzer, which has in principle a 360° field of view in the acceptance plane. Explicit details are given on how the simulation calculations were done. A finite-difference method employing a polar mesh was used for the comput…
DEACIDIFICATION OF PAPER—A MORE FUNDAMENTAL APPROACH
La cellulose provenant du papier de qualité chromatographique et incorporant des quantités diverses de carbonates et/ou d'hydrates d'éléments alcalins ou alcalino-terreux, a été soumise à un vieillissement dans des environnements secs et humides, à des températures allant de 60°C à 105°C. Les valeurs du pH extractif,…
Coupling coefficients for trapezoidal gratings
Using coupled-mode theory, the coupling coefficient was calculated for a trapezoid grating, and it was shown that it is possible to adjust its shape to obtain a high coupling coefficient. This is one of the advantages offered by the ion beam etching technique.>
Molecular asymmetry of an N-alkylporphyrin with enantiotopic faces. Resolution and spectroscopic characterizations of optical antipodes of N-methyletioporphyrin I
The optical antipodes of N-methyletioporphyrin I were resolved and characterized as the zinc complex with a chiral axial ligand by n.m.r. spectroscopy.
Radiation resistivity in silica optical fibers
Hydrogen treatment of optical fiber waveguides with pure silica cores and boron, fluorine codoped silica claddings was found to effectively reduce the y-ray induced loss increases in visible wavelength region. Germanium-doped core fibers free from metal impurities had good resistance against y-rays. The induced losses…
Infinite electrical networks: a reprise
A tutorial on resistive infinite electrical networks at an undergraduate level is presented. Rather than presenting a comprehensive survey on the wide variety of results existing in this subject, the author introduces the basic ideas with several examples and puzzles, examines how the theory branches into two separate…
A Study of the Fundamental Parameters of Some Fancy Yarns
A study is made of the fundamental parameters involved in the production of certain fancy yarns. It is shown how use of these parameters enables an existing fancy yarn to be reproduced without resorting to empirical methods and new yarns exhpirical special pre–selected effects to be created. The method developed is th…
Iridium oxide hydrosols as catalysts for the decay of zinc porphyrin radical cations in water
Iridium oxide hydrosols, containing both IrIII and IrIV sites within a complex oxyhydroxide structure, have been prepared and their interaction with water-soluble zinc porphyrin radical cations has been studied. The colloids possess a negative surface charge so that the positively charged zinc porphyrins are bound to…
Efficiency of natural oils as antifoaming agents in bioprocesses
Abstract The effectiveness and efficiency of nine different natural oils were investigated using simulated fermentation media and several dimensionless coefficients were derived to provide a means for quantitative comparison. Furthermore, correlations between the physical and chemical properties of natural oils and of…
Transannulation route to the [5.5.5.7]-fenestrane ring system of laurenene
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTTransannulation route to the [5.5.5.7]-fenestrane ring system of laureneneGoverdhan Mehta and Kasibhatla Srinivas RaoCite this: J. Org. Chem. 1988, 53, 2, 425–427Publication Date (Print):January 1, 1988Publication History Published online1 May 2002Published inissue 1 January…
Kinetic Aspects of Thermal Analysis
I. INTRODUCTION Roughly 20% of thermoanalytical publications deal with reaction kinetics or contain reaction kinetic evaluations.1 Unfortunately, a great portion of these publications have presented contradictory or meaningless results, which induced a great deal of pessimism about the applicability of reaction kineti…
Composites for high temperatures
Abstract
Controlled roughening of poly(ethylene terephthalate) by photoablation : study of wetting and contact angle hysteresis
The smooth surface of crystalline poly(ethylene terephthalate) films is readily roughened by ablative photodecomposition obtained by absorption of the pulsed far-UV radiation of the excimer laser. The amplitude of this roughness (of the order of 1 μm) is controlled by the intensity of the pulsed radiation and by the n…
Diaminopropionate ammonia-lyase from Salmonella typhimurium. Purification and characterization of the crystalline enzyme, and sequence determination of the pyridoxal 5'-phosphate binding peptide.
We have found a wide occurrence of alpha,beta-diaminopropionate ammonia-lyase in bacteria and actinomycetes. Considerable amounts of this enzyme were found in Salmonella typhimurium. The enzyme was purified and crystallized from S. typhimurium (IFO 12529). The relative molecular mass of the native enzyme, estimated by…
An iron–organic polymeric smoke suppressant for poly(vinyl chloride)
Abstract The incorporation of a poly[ferrocene‐1, 2 (1, 3: 1, 1′)diylmethylene] fraction with M̄ n =2100 as a smoke suppressant additive into both unplasticized and di(2‐ethylhexyl)phthalate‐plasticized, calcium carbonate‐filled poly(vinyl chloride) (PVC) compositions entails appreciable reductions in smoke evolution…
Calculation of forces on magnetised ferrous cores using the Maxwell stress method
The authors examine the problems involved in the application of the Maxwell stress equations for finite-element force calculations on magnetised ferrous cores. They also study the effect of the tangential magnetic field strength H/sub t/ on the accuracy of the force calculation. An effective H/sub t/ value is presente…
Effect of Arrangements of Reinforcements on Mechanical Properties of Ferrocement
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Observation of a re-entrant isotropic phase in a pure disc-like liquid crystal
We report the observation of an optically isotropic phase in the new disc-like mesogen 2,3,7,8,12,13-hexa(octadecanoyloxy)truxene. On cooling, this optically isotropic phase goes over into a nematic phase, while on heating a columnar phase grows in. To our knowledge this is the first example of a pure discotic mesogen…