Application of rigid polyurethane integral-skin foams to thermal insulating unit cases for car air conditioners

Integral-skin foams of rigid polyurethane are sandwich structures consisting of a core layer of closed cells enclosed in rigid surface layers on both sides. We examined the layer composition of integral-skin foam with the objective of maximum flexural strength, and then studied possibilities of reconciling the strength and thermal insulating properties in housings for evaporators in car air conditioners; i.e., unit cases. This examination showed that the most practical density range (250 ≦ ρ_pall ≦ 500 kg/m³) provides vibratile resistance and thermal insulating properties. In actual car-running tests, a maximum 0.1 MPa stress was generated on unit cases with overall densities of 350 kg/m³, We found this to be 0.4% of the flexural strength of an integral-skin foam and 2% of the fatigue strength. In the forcible vibratile test, a stress of 0.5 to 1.0 MPa was generated at the resonance point of a unit case with 250 to 500 kg/m³ overall density. We found that these values are 2 to 5% of integral-skin foam's flexural strength and 10 to 25% of its fatigue strength. These values are of the same level as the conventional unit case made of polypropylene blended with talc. An integral-skin foam with an overall density of 250 kg/m³, nearly equal to half the weight of polypropylene, has the same level of resistance to vibration.     

Representation of the size and shape of a single particle

A method for expressing three-dimensional bodies by a Fourier series expansion is proposed. The equivalent ellipsoid which has the same volume, surface area, and an average projected area as those of a test sample is made obtainable simultaneously. Computer application is explained using a cube as the test sample.     

Composition dependence of lithium ionic conductivity in lithium nitride-lithium iodide system

Two minima in the lithium ionic conductivity vs. composition curve in the lithium nitride-lithium iodide system are observed at Li₅NI₂ and Li₇N₂I. It is shown that ionic conductivity minimum at the stoichiometric Li₅NI₂ is caused by the increase in the lithium ion concentration.     

A random packing structure of equal spheres — statistical geometrical analysis of tetrahedral configurations

A random packing structure constructed by a computer simulation of the slow settling of rigid spheres into a randomly packed bed is investigated, where the bulk-mean volume fraction of the particles is 0.582. Each sphere settled on three others forms a tetrahedron, whose detailed geometrical configuration is successfully examined by a statistical geometrical analysis.     

Chlorine-resistant membrane for reverse osmosis. II. Preparation of chlorine-resistant polyamide composite membranes

Polyethylenetrimesamide (PET), poly(trimesoyl piperazine) (PTP), and poly(m-phenylenetrimesamide) (PMT) were fabricated into thin film composite to evaluate the membrane performance and resistance to oxidative chlorine. The salt rejection of these membrane increased in the following order: PTP<PET<PMT. The degree of performance deterioration of the membrane after the exposure to aq hypochlorous acid was in the following order: PMT>PET>PTP. The reaction behavior of these polyamide membranes with hypochlorous acid could be properly predicted by that of corresponding polyamide powder. Thus, polyethylenetrimesamide has proved to be one of the potential chlorine-resistant reverse osmosis membrane possessing excellent rejection to monosaccharides, amino acids, phenolics, and other solutes having a molar volume larger than 80 cm³/mol.     

Structure-Based Design,Synthesis, and Biological Evaluation of Imidazo[4,5-b]Pyridin-2-one-Based p38 MAP Kinase Inhibitors: Part 2

We identified novel potent inhibitors of p38 mitogen-activated protein (MAP) kinase using a structure-based design strategy, beginning with lead compound, 3-(butan-2-yl)-6-(2,4-difluoroanilino)-1,3-dihydro-2H-imidazo[4,5-b]pyridin-2-one ( 1 ). To enhance the inhibitory activity of 1 against production of tumor necrosis factor-α (TNF-α) in human whole blood (hWB) cell assays, we designed and synthesized hybrid compounds in which the imidazo[4,5-b]pyridin-2-one core was successfully linked with the p-methylbenzamide fragment. Among the compounds evaluated, 3-(3-tert-butyl-2-oxo-2,3-dihydro-1H-imidazo[4,5-b]pyridin-6-yl)-4-methyl-N-(1-methyl-1H-pyrazol-3-yl)benzamide ( 25 ) exhibited potent p38 inhibition, superior suppression of TNF-α production in hWB cells, and also significant in vivo efficacy in a rat model of collagen-induced arthritis (CIA). In this paper, we report the discovery of potent, selective, and orally bioavailable imidazo[4,5-b]pyridin-2-one-based p38 MAP kinase inhibitors.     

Actual ratios of triacylglycerol positional isomers consisting of saturated and highly unsaturated fatty acids in fishes and marine mammals

The distribution of fatty acid species at the (sn-1, 3) position or the (sn-2) position of triacylglycerol (TAG) in natural fats and oils has already been analysed by many researchers and several interesting results have been reported. However, most of these reports only focused on the distribution of fatty acids at the or positions in TAG, and did not take account of the combination of fatty acids in the TAG, i.e., the TAG positional isomers. In this study, the actual ratios of TAG positional isomer pairs, consisting of palmitic acid and highly unsaturated fatty acid (HUFA) such as DHA or EPA, in fish and marine mammals were investigated using a high-performance liquid chromatography/atmospheric pressure chemical ionisation-mass spectrometry (HPLC/APCI-MS) system equipped with tandem jointed non-endcapped polymeric ODS columns. The results show that for combinations of DHA or EPA with two palmitic acids in the TAG of marine mammals, binding was almost all at the α position. In contrast, binding of DHA or EPA was mainly at the β position in fish. The preferred DHA and EPA positions in TAG were the same in the same marine mammal or fish. The binding position tendency of HUFA in TAG positional isomers consisting of two HUFAs and one palmitic acid was the same as that for combinations of one HUFA and two palmitic acids. These results were interpreted as showing that the preferred fatty acid species of sn-glycerol-3-phosphate acyltransferase and 1-acyl-sn-glycerol-3-phosphate acyltransferase in marine mammals are different to those in fish and other animals, or that diacylglycerol acyltransferase in marine mammals favours 1,2-dipalmitoyl-sn-glycerol formed from 1,2-dipalmitoyl-sn-glycerol-3-phosphatidate if HUFA is the reaction substrate.     

On the nature of “easy paths” for the diffusion of oxygen in thermal oxide films on aluminum

Thermal oxide films grown on electropolished aluminum specimens have been investigated by transmission electron microscopy of stripped oxide films and ultramicrotomed sections. Particular attention has been focused on the nucleation sites -Al ₂ O ₃ crystals and the relationship of such sites to surface features on the electropolished aluminum surface. It is evident that easy paths for the diffusion of oxygen, or the nucleation sites of -Al ₂ O ₃ crystals, are not distributed randomly over the electropolished aluminum surface, but form preferentially in the amorphous oxide layer grown over preexisting metal ridges. Thus, the diffusion of molecular oxygen through cracks in the amorphous oxide layer represents the most realistic and acceptable basis for explaining the local growth of the -Al ₂ O ₃ crystals in thermal oxide films on aluminum, although the cracks have not yet been observed directly.Present address: Alcan International, Ltd., Banbury Laboratories, Banbury, Oxford, OX16 7SP, United Kingdom.     

Chaotic behavior of an elastoplastic bar in tensile test over a wide range of strain rate: a numerical investigation

Numerical tensile tests of an elastoplastic cylindrical bar at various high strain rates are performed by the use of a dynamic explicit FEM code (DYNA3D, a public domain version). The effects of mass (inertia) of the body, strain rate and strainrate sensitivity exponent (m-value) on the deformation pattern and the load curve are investigated. As for the material, strain-dependent nth power work hardening property is given by where is strain rate. The range of the prescribed average strain rate is 50–1000/s where the tensile tests with constant average strain rate and with constant tensile velocity are performed. Materials with higher density exert a greater influence on deformation mode at a high strain rate. Even if the tensile speed is less than that of plastic wave propagation, the deformation becomes non-uniform remarkably due to mass effect. It is unexpected that double necking occurs at certain computational conditions. The strain at maximum load point predicted by the numerical simulation does not coincide with the analytically predicted one. Maximum rate of decrease in cross sectional area within the straight portion of the bar is compared with Hart's instability criterion based on the imperfection in the cross section. In high-rate tension over , deformation behavior is chaotic in the sense that it varies very sensitively with a trivial change in material properties and/or in the prescribed strain rate.