Behaviour of cobalt infiltration and abnormal grain growth during sintering of diamond on cobalt substrate

The infiltration behaviour of molten cobalt into a diamond powder compact was examined when the latter was placed on a cobalt disc and held at high pressure of 5.8 GPa and high temperature of 1350 to 1500° C. The larger the grain size of the starting diamond powder and the higher the holding temperature, the more easily cobalt infiltrated into the diamond compact. The infiltration is considered to occur because of the negative pressure in the voids formed between diamond grains. Although diamond powder was consolidated in this process of cobalt infiltration, abnormal grain growth was also observed in the boundary between cobalt and diamond compact because of the dissolution and precipitation process of the compact into molten cobalt.On leave from Chengdu University of Science and Technology, Chengdu, China.     

Cupric ion-dependent inhibition of lysosomal acid cholesteryl ester hydrolase in the presence of hydroxylamine

In the presence of hydroxylamine or ascorbic acid, the inhibitory effects of Cu²⁺ on lysosomal acid cholesteryl ester hydrolase (acid CEH) partially purified from rat liver were studied. Hydroxylamine stimulated the inhibition of acid CEH activity by Cu²⁺ but not that by Zn²⁺, Fe²⁺, Co²⁺, Mn²⁺, Ca²⁺, Mg²⁺ and Hg²⁺. This Cu²⁺-dependent inhibition of acid cholesterol ester hydrolase (CEH) activity was completely prevented by ethylenediamine tetraacetic acid (EDTA), EGTA and o-phenanthroline, a chelator with a stability constant for Cu²⁺, and also by sulfhydryl agents and cytoplasmic reducing agents such as cysteine, glutathione and mercaptoethanol. In addition, the stimulative effects of hydroxylamine on Cu²⁺-dependent inhibition were maintained even after preincubation of Cu²⁺ with hydroxylamine. On the other hand, ascorbic acid was found to replace the stimulation by hydroxylamine of the Cu²⁺-dependent inhibition of acid CEH activity but the effects of ascorbic acid progressively became smaller with prolongation of the preincubation time. Moreover, addition of chemical radical scavengers to the reaction mixture did not prevent the Cu²⁺-dependent inhibition of acid CEH activity in the presence of ascorbic acid. These results suggest that Cu²⁺ causes inhibition of lysosomal acid CEH activity through the formation of Cu¹⁺ in a reductive medium.     

A new method for generating group constants for analysis of blanket parameters of HCLWR with Monte Carlo method

The preliminary analysis of natural uranium blanket region at the KUCA was carried out with continuous energy monte carlo method and group energy monte carlo method. From the results obtained, it is clear that group constants weighted with scalar neutron spectrum cannot predict the transitory effect of the forward biased on neutron angular distribution. It is suggested that the direction-dependent group constants have to be used to predict the reaction rate in the blanket region accurately.     

Effect of cupric ions on serum and liver cholesterol metabolism

Cupric ions were administered subcutaneously to male Sprague-Dawley rats at a single dose of 200 μmol/kg. At 24 hr after administration, a remarkable increase of total and free cholesterol was seen in the rat serum. Also, when lecithin-cholesterol acyltransferase (LCAT) (E.C. 2.3.1.43) activity was expressed as the percentage of the total serum that free cholesterol esterified, the acyltransferase activity in rats treated with cupric ions showed a slight decrease while the triglyceride content in rat serum and liver decreased by 54% and 61%, respectively. However, the content of hepatic cholesterol in rats treated with cupric ions did not show such a marked change. On the other hand, acid cholesteryl ester hydrolase activity (Acid CEH) (E.C. 3.1.1.14) in liver lysosomes of rats treated with cupric ions showed a marked decrease with increasing cupric ion concentration both in vivo and in vitro. Furthermore, cupric ions caused a marked release of the lysosomal enzymes cathepsin D and β-glucuronidase into the cytosolic fraction. The changes in acid cholesteryl ester hydrolase activity induced by cupric ions appear to be a direct effect of cupric ions on the enzyme. These results suggest that excessive cupric ion concentrations could cause various disorders in lipid metabolism.     

Melt rheology of ionomer filled with methyl methacrylate–grafted perlite

The shear viscosity, the shear compliance, and their shear rate dependence were determined by a Weissenberg rheogoniometer, and the effect of the grafted poly(methyl methacrylate) chains on the intensification of the interaction at the interface between the ionomer matrix and the filler was discussed. Results were as follows: (1) The relative viscosity of the ionomer filled with MMA-grafted perlite to the matrix ionomer and the yield stress increased with increase in the volume fraction of perlite, and these behaviors were more remarkable in the case of the perlite with larger quantity of grafted PMMA. (2) The effective thickness of the immobilized matrix layer on the filler surface in the Ziegel equation and the crowding factor in the Mooney equation showed larger values in the case of the filled systems of MMA-grafted perlite than in the case of the unmodified perlite. (3) At the same total volume fraction which was the sum of the quantities of the perlite and the grafted PMMA, the relative viscosity and the crowding factor showed respectively a maximum with the quantity of grafted PMMA. (4) The shear compliance of these filled systems decreased with perlite content. A little effect of the amount of grafted PMMA on the compliance was observed at the same volume fraction of perlite. According to these rheological properties, it could be concluded that the grafted PMMA chains were effective in increasing the interaction between the ionomer matrix and the perlite at their interface, particularly in the lower shear rate region.     

In situ X-ray analysis of mechanism of nonlinear super elastic behavior of Ti–Nb–Ta–Zr system beta-type titanium alloy for biomedical applications

Ti–XNb–10Ta–5Zr (mass %) alloys based on nominal compositions of Ti–35Nb–10Ta–5Zr, Ti–30Nb–10Ta–5Zr, and Ti–25Nb–10Ta–5Zr were fabricated through powder metallurgy and forging and swaging processes for biomedical applications. The tensile deformation mechanisms of the Ti–25Nb–10Ta–5Zr, Ti–30Nb–10Ta–5Zr, and Ti–35Nb–10Ta–5Zr alloys were investigated in situ by X-ray diffraction analysis under several loading conditions.Under the loading conditions, the X-ray diffraction peaks of all the specimens shifted to higher angles than those obtained under the unloading conditions. For the Ti–30Nb–10Ta–5Zr alloy, the elastic deformation is considered to progress continuously in a different crystal direction although after the elastic strain reaches elastic limit in the crystal direction where the elastic limit is the smallest, slip deformation occurs in that crystal direction. The elastic modulus of this alloy appears to decrease in terms of strain over the proportional limit. Thus, the elastic deformation behavior of the Ti–30Nb–10Ta–5Zr alloy does not obey Hooke's law.     

Remote calibration of ionization chambers for radioactivity calibration

A new calibration technique, referred to as e-trace, has been developed by the National Institute of Advanced Industrial Science and Technology (AIST). The e-trace technique enables rapid remote calibration of measurement equipment and requires minimal resources. We calibrated radioisotope calibrators of the Japan Radioisotope Association (JRIA) and the Nishina Memorial Cyclotron Center (NMCC) remotely and confirmed that remote calibration provided results that are consistent with the results obtained by existing methods within the limits of uncertainty. Accordingly, e-trace has been approved as the standard calibration method at AIST. We intend to apply remote calibration to radioisotope calibrators in hospitals and isotope facilities.     

Effect of solar control glazings on human skin temperature

Human skin temperatures were measured under exposure to near-infrared radiation through solar control glazings containing SiWO_x films as solar control materials. It was found that the increase in skin temperature corresponds to the solar transmittance (T_s) value of the glazings. When the hand was exposed to radiation through a glazing containing solar films, the skin temperature after five minutes was less 0.9–1.8°C lower than when the corresponding glass without the films was used. The solar control glazings were effective in reducing the increase in skin temperature.     

Impact of heat processing on the detection of the major shellfish allergen tropomyosin in crustaceans and molluscs using specific monoclonal antibodies

The major heat-stable shellfish allergen, tropomyosin, demonstrates immunological cross-reactivity, making specific differentiation of crustaceans and molluscs for food labelling very difficult. The aim of this study was to evaluate the application of allergen-specific monoclonal antibodies in differential detection of shellfish-derived tropomyosin in 11 crustacean and 7 mollusc species, and to study the impact of heating on its detection. Cross-reactive tropomyosin was detected in all crustacean species, with partial detection in molluscs: mussels, scallops and snails but none in oyster, octopus and squid. Furthermore, we have demonstrated that heating of shellfish has a profound effect on tropomyosin detection. This was evident by the enhanced recognition of multiple tropomyosin variants in the analysed shellfish species. Specific monoclonal antibodies, targetting the N-terminal region of tropomyosin, must therefore be developed to differentiate tropomyosins in crustaceans and molluscs. This can help in correct food labelling practices and thus protection of consumers.