Fe-Si系溶液を用いたSiC単結晶の溶液成長の界面現象と速度論

学位の種別:課程博士University of Tokyo(東京大学

Using ultrasonography in evaluating the intramuscular injection techniques used for administering drug treatments to schizophrenic patients in Japan

This study was conducted with six patients with schizophrenia, four of whom received the atypical antipsychotic risperidone long-acting injectable (RLAI), and two patients receiving the typical depot injection (TDI). The purpose of this study was to determine the location (gluteus medius or maximus ; deltoid muscles) and diffusion of typical and atypical antipsychotic medications administered intramuscularly using ultrasonography. When using the standardized depth of needle insertion, in some cases, the drug was injected into the gluteus maximus instead of the gluteus medius. Similarly, in some cases the TDI was not visible in the ultrasonographic images until sixteen days after the injection. This verifies how hard the injection site becomes when microspheres of RLAI is injected as compared to other muscle areas. These results confirmed that the gluteus muscle structure was the ideal muscle for depot injection as evidenced by the injection solution being dispersed and rendered not visible immediately after intramuscular injection (IM). With the use of ultrasonography, injection sites and drug dispersions were evaluated under a direct visual guidance, suggesting that ultrasonography is a useful method for establishing evidence for determining correct insertion of IM injection, diffusion of medications, and the effective administration of IM injections

Contribution of Dislocations in SiC Seed Crystals on the Melt-Back Process in SiC Solution Growth

The melt-back process has a significant effect on the quality of solution-grown SiC crystals. However, the phenomena surrounding the SiC dissolution into the molten alloy during the melt-back process have not been clarified. In this study, the behavior of 4H-SiC dissolution into molten alloy was investigated by using high-temperature in situ observation and subsequent KOH etching, and the effects of different doping conditions and crystal polarity were studied. Local dissolutions with hexagonal pyramid-shape originating from threading screw dislocation (TSD) were observed on the C face of n-type SiC with light nitrogen doping. Our analysis of their behavior revealed that the process was governed by the spiral dissolution. In addition to the dissolution at TSD, local dissolutions at threading-edge dislocations were observed on the Si face of the same crystal. The shape of the local dissolution at the dislocation was significantly affected by the doping conditions and the polarity of the SiC crystal. This local dissolution may occur during the melt-back process, suggesting that it is important to promote the dissolution while maintaining a smooth interface through the selection of the seed crystal and by keeping the degree of interface undersaturation small

In Situ Interferometry for ppm-Order Solubility Analysis at High Temperatures: A Case Study of Carbon Solubility in Molten Silicon

International audienceThe precise solubility data of a component in high-temperature melts are essential for the design and optimization of various processes including pyrometallurgical and solution growth processes. In this study, we developed an in situ method for measuring the solubility of a component in molten metals and alloys and investigated C solubility in molten Si using a system comprising Si and SiC substrate. The three-dimensional interfacial shape between the SiC substrate and molten Si droplet was analyzed from images captured by interferometry utilizing the internal interference in the SiC substrate. From the changes in interfacial shape, the temperature dependence of C solubility in molten Si up to 1873 K was successfully evaluated in the single experiment. The obtained C solubilities were in accordance with the smallest solubilities ever reported, suggesting a reliable evaluation because overestimations sometimes happen in the conventional point-by-point measurements of quenching samples. In addition, the excess partial molar Gibbs energy of C in molten Si was evaluated thermodynamically. The proposed method enables the in situ and crucible-free quantitative analysis of the solubility of a component in molten metals and alloys in the order of a few tens to hundreds of ppm for various material systems at high temperatures