Thermodynamic study of the phase equilibria in the Sn−Ti−Zn ternary system

The Sn−Ti−Zn ternary phase diagram has been constructed using the CALPHAD technique. The Ti−Zn binary system phase boundaries were determined using differential scanning calorimetry and the solid-liquid diffusion couples method. In addition, the formation energy of some stoichiometric compounds was obtained using first-principle band energy calculations. For the ternary system, some alloys were prepared by equilibration at 600 or 700 °C, and the compositions of the precipitates were analyzed using electron probe microanalysis. Thermodynamic assessment of the Ti−Zn and Sn−Ti−Zn systems was performed based on the experimental information and by adopting reported values of the thermodynamic properties of the Sn−Zn and Sn−Ti binary systems. Microstructural observation showed that Sn₃Ti₅Zn₁₂ exists in the ternary system. Seven types of invariant reaction on the Sn-rich liquidus surface of the ternary system are predicted by the phase diagram calculations. The ternary eutectic point falls at 0,0009 mass% Ti and 8.69 mass% Zn, at T=192.40°C, which is slightly lower than the calculated eutectic point of Sn−Zn binary alloy (T=192.41°C). Based on these results, a nonequilibrium solidification process using the Scheil model was simulated. This paper was presented at the International Symposium on User Aspects of Phase Diagrams, Materials Solutions Conference and Exposition, Columbus, Ohio, 18–20 October, 2004.     

Potent inhibitors of secretory phospholipase A2: synthesis and inhibitory activities of indolizine and indene derivatives

Phospholipase A2 is an enzyme which hydrolyzes the sn-2 position of certain cellular phospholipids. The liberated lysophospholipid and arachidonic acid are precursors in the biosynthesis of various biologically active products. As human nonpancreatic sPLA2 is present in high levels in the blood of patients in several pathological conditions, the potent sPLA2 inhibitors have been suggested to be useful drugs. Here we describe the synthesis, structure-activity relationship, and inhibitory activities of indolizine and indene derivatives. 1-(Carbamoylmethyl)indolizine derivatives and 1-oxamoylindolizine derivatives exhibited very potent inhibitory activity. The former was unstable to air oxidation, but the latter exhibited an improvement both in stability and in potency. Some compounds approached the stoichiometric limit of the chromogenic assay.     

Clinicopathological analysis and therapy in hepatitis C virus-associated nephropathy

The authors evaluated, using computer image analysis system, 15 renal biopsy specimens from patients with MCD and 15 from patients with FSGS. As a control group 5 biopsy and 10 autopsy renal specimens were used. These studies revealed, that in MCD glomeruli showed proliferative changes unrecognizable by light microscopy. In FSGS glomeruli without sclerotic changes were larger than in controls and showed glomerular cells proliferation (per unit of glomerular area) similar to MCD. FSGS in comparison with MCD showed larger glomeruli and prominent interstitial fibrosis. These observations appeared to be helpful in distinguishing MCD and recent forms of FSGS. There were no correlations between relative interstitial volume and glomerular changes in MCD as well as in FSGS. The authors concluded, that histomorphometry can't be used instead of morphological examinations of renal biopsy specimens, but it gives objective informations about progression of the illness and may be useful in differential diagnosis of selected cases of MCD and FSGS.     

Real-time IR and mass spectroscopic study of the reaction process of WF6 and a-Si:H:F

The deposition process of W from WF₆ onto a-Si:H:F film was studied by polarization modulation IR spectroscopy combined with quadruple mass spectrometry. The IR spectrum of the a-Si:H:F film formed by the spontaneous chemical deposition method (deposition temperature 373 K) showed that such fluorinated and hydrogenated Si species as —SiF₂, —SiF₂H and —SiH₂ were incorporated in the film. The lowest temperature at which W was deposited was 403 K. The intensity reduction of the IR bands due to the hydrogenated and fluorinated Si species as well as the evolutionary behaviour of the reaction products SiF₄ and H₂ depended upon the reaction temperature. At temperature between 403 K and 423 K, the IR band intensity of the —SiH₂ species remained unchanged in early stages of WF₆ exposure, while the bands due to —SiF₂ and —SiF₂H species decreased linearly with exposure time. No evolution of H₂ was observed as long as the —SiH₂ species remained unchanged, through SiF₄ evolved into the gas phase just after the beginning of the exposure. These results suggest that WF₆ reacts preferentially with the fluorinated silicon species in the films.     

INITIATION AND GROWTH OF SMALL CRACKS IN DIRECTIONALLY SOLIDIFIED MAR-M247 UNDER CREEP-FATIGUE. PART I: EFFECT OF MICROSTRUCTURE

This paper deals with the initiation and growth of small cracks in a directionally solidified superalloy, Mar-M247.     

Image-transmission of radiotherapy planning using 64kbps-ISDN videophone

We carried out the image-transmission using the 64kbps-ISDN and two terminals of the videophone installed in Osaka Teishin Hospital and Department of Radiation Oncology, Biomedical Research Center, Osaka University Medical School. The frame speeds (sec./frame) of the videophone are 1.2 for standard resolution with 320 x 200 matrix and 5.0 for high resolution with 640 x 400 matrix. Although the image with 640 x 400 matrix is not enough for the radiation diagnosis such as the chest radiogram, the image is useful for the radiation therapy planning. This system is easy to operate, and will be widely distributed in near future.     

Nonlinear stress analysis for thin spherical vessels with local non-axisymmetric imperfections

On a thin spherical shell with a local and non-axisymmetric imperfection, the magnitude of the strain concentration occurring around the imperfect region was investigated by means of a finite element method, and the quantitative determination method of it was theoretically studied. In a stress analysis of the thin shell structures, a large deformation analysis considering geometrical nonlinearity of the imperfect regions was practically necessary and important, as reported previously in detail (Ohtani et al., Int. J. Pres. Ves. & Piping, 45 (1991) 3–21). As a result of this analysis, it was seen that the imperfection induced a considerably high strain concentration, even if the amplitude of imperfection was very small, and that a tendency of strain concentration due to loading of internal pressure apparently showed a nonlinearity to the pressure. Furthermore, from a comparison of the present results for the local non-axisymmetric imperfection with the previous ones for the banded axisymmetric imperfection, which deformed uniformly on circumferential direction, it was found that a tendency of strain concentration due to this kind of local imperfection was basically similar to that of the uniform axisymmetric one. Therefore, it was clarified that the magnitude of strain in the local non-axisymmetric imperfection was calculated in practical accuracy by using the formulae presented in the previous paper for the axisymmetric one.     

Clarification of strain limits considering the ratcheting fatigue strength of 316FR steel

The effect of ratcheting on fatigue strength was investigated in order to rationalize the strain limit as a design criterion of commercialized fast reactor systems. Ratcheting fatigue tests were conducted at 550 °C. Duration of the ratchet straining was set for a certain number of strain cycles taking the loading condition of fast reactors into account, and the number of cycles for strain accumulation was defined as the ratchet-expired cycle. Fatigue lives decrease as the accumulated strain by ratcheting increases. Mean stress increased during the ratcheting cycle and its maximum value depended on the accumulated strain and the ratchet-expired cycle. Fatigue life reduction was negligible when the maximum mean stress was less than 25 MPa, corresponding to an accumulated strain of 2.2%. Accumulated strain is limited to 2% in the present design guidelines and this strain limit is considered effective to avoid reducing fatigue life by ratcheting. Microcrack growth behaviors were also investigated in these tests in order to discuss the life reduction mechanisms in ratcheting conditions.