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Oxidation resistance and oxidation mechanism of a carbon/carbon composite (C/C composite), on which inner layer of TiC and outer of SiC were coated by chemical vapor deposition, were investigated. The CVD conditions used were, TiCl4-CH4-H2 or SiCl2-CH4-H2 system, deposition temperatures ranging from 1050° to 1350°C and total gas pressures ranging from 40 to 100 Torr. TiC coating was 7-50μm thick and SiC coating was 70-270μm thick. The oxidation resistance of the coated C/C composite was estimated from room temperature to 1300°C in air using several heating programs. In two layers-coating, the number of thermal cracks which generated on the surface of the coated layer decreased and the oxidation resistance improved depending on the thickness ratio of TiC to SiC coating as compared with SiC monolayer-coating. It is recognized that large compressive stress generated in the outer layer of SiC and TiO2 (rutile) formed along the thermal cracks in the coated layers after the oxidation.

A machinability of porous Si3N4 ceramics composed of columnar β-Si3N4 grains was evaluated by turning and milling with cemented carbide cutting tools to investigate a possibility of application of the porous Si3N4 to machinable ceramic use. The porosity and the flexural strength of specimens were about 43% and 270MPa, respectively. The machinings were carried out with a cemented carbide throw-away tip of K-10 grade. The condition of turning was cutting speeds of 50 to 150m/min, feed rates of 0.05 to 0.40mm/rev, and a cutting depth of 0.5mm, and that of milling was cutting speeds of 20 to 200m/min, feed rates of 0.05 to 0.20mm/rev and a cutting depth of 0.5mm. Machinability was judged from the maximum surface roughness, Rmax, after machining; it was defined that a material was machinable when Rmax was below 10μm. In the case of turning, the Rmax increased with increasing cutting speed and feed rate. Rmax below 10μm was obtained under conditions that satisfied both a cutting speed of 50m/min and feed rates below 0.1mm/rev. In the case of milling, although the Rmax increased with increasing feed rate, serious cutting speed dependence of Rmax could not be seen. Rmax values below 10μm were obtained at feed rates below 0.1mm/rev, independent of cutting speed.

The calculation of likelihood ratios (LRs) for DNA mixture analysis is necessary to establish an appropriate hypothesis based on the estimated number of contributors and known contributor genotypes. In this paper, we recommend a relevant analytical method from the 15 short tandem repeat typing system (the Identifiler multiplex), which is used as a standard in Japanese forensic practice and incorporates a flowchart that facilitates hypothesis formulation. We postulate that: (1) all detected alleles need to be above the analytical threshold (e.g., 150 relative fluorescence unit (RFU)); (2) alleles of all known contributors should be detected in the mixture profile; (3) there should be no contribution from close relatives. Furthermore, we deduce that mixtures of four or more persons should not be interpreted by Identifiler as the LR values of 100,000 simulated cases have a lower expectation of exceeding our temporal LR threshold (10,000) which strongly supports the prosecution hypothesis. We validated the method using various computer-based simulations. The estimated number of contributors is most likely equal to the actual number if all alleles detected in the mixture can be assigned to those from the known contributors. By contrast, if an unknown contributor(s) needs to be designated, LRs should be calculated from both two-person and three-person contributions. We also consider some cases in which the unknown contributor(s) is genetically related to the known contributor(s).

Titanium silicides are well known as intermetallic compounds having excellent heat resistance and high hardness. However, it is difficult to fabricate the compounds using the powder sintering method to produce the strong bonding force between atoms characteristic of the compounds. Chemical vapour deposition (CVD) has been a useful method of fabricating a series of intermetallic compounds. In many CVD processes, thermal CVD without plasma is known as a thermally equilibrated process. Therefore, it is possible to predict the deposited phases by means of previous thermodynamic calculations. Many studies have been reported on titanium silicides. Wahl et al. reported the deposition of Ti-Si compounds from the Ti -S i -H-C1 system [1]. Other studies have considered the T i S i C H C 1 system. Most of these have reported both the synthesis and the thermodynamic calculations for a variety of composites consisting of Ti-Si-C, and compared the experimental results with the calculations [2-8]. These reports mention the rare case in which non-equilibrium phases deposit, even in the thermal CVD process. The fabrication of TiC-SiC composites performed by Stinton et al. [2] included the deposition of TiSi2 phase, which was not predicted by the thermodynamic calculation. Similarly, Goto and Hirai [3, 4] suggested that the difference in the deposited phase between the experiments and the calculations might be caused by kinetic restriction. However, detailed kinetic studies, such as deposition rate, have not been reported. In the research reported here, we found a high rate deposition of titanium silicides, which were non-equilibrium phases in a CVD system, under high gas flow rate. Fig. 1 shows the CVD apparatus. TiCI4, SiC14, CH 4 and H2 were used as source materials. The L

The purpose of this study was to compare the functional utility of intraoperative ultrasonography (IOUS) and cholangiography (IOC) during a laparoscopic cholecystectomy for the treatment of gallstone disease.A prospective study comparing IOUS and IOC was carried out in 65 patients. Intraoperative ultrasonography was conducted first using a 7.5-MHz linear array probe. After IOUS, IOC was then conducted in all patients. The respective usefulness of IOUS and IOC in the identification of gallstones, detection of hepatobiliary structures, and demonstration of congenital anomalies was then compared.Intraoperative ultrasonography was successful in all 65 patients, and IOC was successful only in 54. The time required for IOUS was significantly shorter (p0.0001) than for IOC. Intraoperative ultrasonography imaged the hepatic ducts and their confluence, the common hepatic duct, the common bile duct, and the ampulla of Vater in 97, 100, 97, and 51% of cases, respectively. Intraoperative cholangiography, on the other hand, depicted these structures in 85, 89, 100, and 94% of cases, respectively. Intraoperative ultrasonography demonstrated the cystic duct and its confluence in 94% of cases. Biliary anomalies were identified by IOUS in 12 patients and by IOC in 13. Intraoperative ultrasonography could detect the hilar vascular structures in most patients and visualized anomalies of the hepatic arteries in 5 patients. In this series, 5 patients had choledocholithiasis. The sensitivities, specificities, positive and negative predictive values, and accuracies in identifying these bile duct stones were 80, 98, 80, 98, and 97% by IOUS, and 80, 97, 67, 98, and 95% by IOC, respectively.Intraoperative ultrasonography is superior to cholangiography with respect to its safety, shorter examination period, and ease of administration in all patients. In addition, IOUS is also better for identifying subtle anatomic detail. Intraoperative ultrasonography compares favorably with IOC in terms of utility in exploring bile ducts for stones. Intraoperative ultrasonography is an effective procedure for biliary exploration during a laparoscopic cholecystectomy.

It is hard to generate twin defects in wurtzite-type ZnMS (M: metal element) crystals by static mechanical method, while it is important for the luminescence. It was found that many twin defects were formed in wurtzite-type ZnMgS crystals by shock compression of >15 GPa in stress, and the absorption and luminescence spectra changed.

Fine-grained silicon nitride (Si3N4) whiskers were coated on Si3N4 fibers through a vapor-liquid-solid mechanism under the following process. After the oxide glass of a Si-Al-Y-O system was coated on seed Si3N4 fibers, the coated fibers were heated at 1490°C and 700° in the vapor of the Si-N system which was generated by decomposition of amorphous Si3N4. The resulting specimens looked just like rose twigs. The Si3N4 whiskers were precipitated by nucleation in a liquid phase generated by melting of the oxide glass layers on the Si3N4 fibers.