Eutectic Morphology of Al-7Si-0.3Mg Alloys with Scandium Additions

The mechanisms of Al-Si eutectic refinement due to scandium (Sc) additions have been studied in an Al-7Si-0.3Mg foundry alloy. The evolution of eutectic microstructure is studied by thermal analysis and interrupted solidification, and the distribution of Sc is studied by synchrotron micro-XRF mapping. Sc is shown to cause significant refinement of the eutectic silicon. The results show that Sc additions strongly suppress the nucleation of eutectic silicon due to the formation of ScP instead of AlP. Sc additions change the macroscopic eutectic growth mode to the propagation of a defined eutectic front from the mold walls opposite to the heat flux direction similar to past work with Na, Ca, and Y additions. It is found that Sc segregates to the eutectic aluminum and AlSi₂Sc₂ phases and not to eutectic silicon, suggesting that impurity-induced twinning does not operate. The results suggest that Sc refinement is mostly caused by the significantly reduced silicon nucleation frequency and the resulting increase in mean interface growth rate.     

Replication of rat coronaviruses in intestinal cell line, RCN-9, derived from F344 rats

To examine the susceptibility of the epithelial cell line to rat coronavirus (RCV), we inoculated sialodacryoadenitis virus and Parker's RCV into five cell lines; JTC-19, rat L2, LLC, RCN-9 and LBC cells originating in the lungs, intestines and mammary tumors of rodents. Both RCVs were replicated in LBC and RCN-9 cells, but not in the others. The infectivity titers of both RCVs grown in RCN-9 cells were significantly higher than those in LBC cells in every passage (2.5-3.9 log rate). Both RCVs replicated in LBC cells showed higher tropism to RCN-9 cells than to LBC cells, suggesting that RCN-9 cells are more suitable for the replication of RCVs than LBC cells. The RCN-9 cell line would be useful for the investigation of RCV infection in rodents.     

The effects of treatment with lipopolysaccharide on responsiveness of rat blood vessels

Effects of treatment with lipopolysaccharide (LPS) both in vivo (intraperitoneal administration of 20 mg.kg-1 LPS for 6 hours) and in vitro (incubation with 1 microgram.kg-1 LPS for 6 hours) on the responsiveness of the rat thoracic aorta, carotid, renal, femoral, mesenteric, pulmonary arteries, and the femoral and mesenteric veins were examined. Intraperitoneal administration of LPS did not change the blood pressure of rats, but increased the heart rate significantly. The same amplitude of relaxation was produced by L-arginine in the aortic strips treated by LPS in vivo and in vitro, and the responses were inhibited by NG-nitro-L-arginine (L-NOARG). The contractile responses to phenylephrine in the aortic strips were reduced by LPS-treatment in vivo or in vitro, but the extent of inhibition was greater in vivo than in vitro. Further, the attenuation of contractile responses to phenylephrine was completely reversed by L-NOARG in the strips treated with LPS in vitro, whereas the reversal by L-NOARG was incomplete in the strips treated with LPS in vivo. Different amplitudes of relaxations were also produced by L-arginine or SNP in the blood vessels treated by LPS in vivo or in vitro. However, the tail artery treated with LPS in vivo or in vitro did not relax in response to L-arginine but did produce a relaxation to SNP. These results suggest that the hyporesponsiveness of rat blood vessels after treatment with LPS in vivo or in vitro may be related to an enhanced NO production in the smooth muscle cells and that there is a possible heterogeneity of regional induction or activation of L-arginine/NO pathway by LPS in rat blood vessels.     

Effect of Manganese Oxide Additive on the Dielectric Properties of Mixed-Sintering Ceramics

The influence of internal electrode material on the sintering of mixed-sintering ceramics and the effect of MnO₂ additive on improving their dielectric properties were investigated for their application as multilayer ceramic capacitors. The resistivities of mixed-sintering ceramic pellets sintered with Ag-Pd electrode material decreased remarkably because of the expulsion of component elements during sintering. A small amount of MnO₂ additive improved the resistivities. Extended X-ray absorption fine-structure analysis showed that MnO₂ exists in the grain boundaries and compensates for the electrical valence of the expelled elements.     

煅烧炉用喷射耐火料的近期发展趋向

开发了一种干式喷射隔热材料,其热导率与隔热板一样低.它正取代普通的隔热板,因它的安装方便,工作环境较好.另外,我们已开发了新的湿式喷射料体系,它效率高,工作环境好.     

Intratumoral pharmacokinetics and in vivo gene expression of naked plasmid DNA and its cationic liposome complexes after direct gene transfer

The pharmacokinetic properties and gene expression of naked plasmid DNA and its cationic liposome complexes were studied after direct intratumoral injection. Using a Walker 256 tissue-isolated tumor perfusion system, we quantified the recovery of naked plasmid DNA and cationic liposome complexes in the tumor, leakage from the tumor surface, and the venous outflow after intratumoral injection. Approximately 50% of naked plasmid DNA had been eliminated from the tumor 2 h after injection, whereas more than 90% of plasmid DNA was retained in the tumor when it was complexed with cationic liposomes. However, the distribution of these complexes in the tumor was restricted to the tissue surrounding the injection site. Pharmacokinetic analysis of the venous outflow profiles suggested that the rate-limiting process that determines the retention of plasmid DNA in the tumor is transferred from the injection site in the tumor tissue and that complexation with cationic liposomes may retard this process. Furthermore, we examined the gene expression of chloramphenicol acetyltransferase DNA constructs (naked pCMV-CAT) and the corresponding cationic liposome [3-beta-(N-(N',N'-dimethylaminoethane)carbamoyl)cholesterol] complexes. A similar level of gene expression was observed in vivo after direct intratumoral injection of naked DNA and its cationic liposome complexes. In both cases, a great variation was observed between tumors, and localization of gene-transduced cells in the tumor tissue was limited to the area in the vicinity of the injection site. Thus, these pharmacokinetic and gene expression studies have demonstrated that cationic liposomes can enhance the retention of injected DNA in the tumor model, whereas cationic liposome complex does not necessarily improve gene expression because of its poor dissemination in this tumor. The present study also suggested that there is a need to control the behavior of the injected naked plasmid DNA and its cationic liposome complexes to ensure better distribution throughout the tumor.     

Long-term results of Watson-Jones tenodesis of the ankle. Clinical and radiographic findings after ten to eighteen years of follow-up

Thirty-seven chronically unstable ankles in thirty-six patients were operated on with use of a Watson-Jones tenodesis. Thirty-four ankles (thirty-three patients) were followed for a mean duration of thirteen years and eight months (range, ten to eighteen years) after the operation. There were nine male and twenty-four female patients. The mean age of the patients was thirty-one years (range, fourteen to fifty-seven years) at the time of the operation and forty-four years (range, twenty-eight to seventy years) at the time of the latest follow-up. At the time of the most recent follow-up evaluation, twenty-seven patients (twenty-eight ankles) were examined directly by one of us and twenty-five patients (twenty-six ankles) also were evaluated radiographically. The other six patients were interviewed, with use of a questionnaire, by telephone. Of the thirty-four ankles, nineteen had an excellent result (grade 1), eleven had a good result (grade 2), three had a fair result (grade 3), and one had a poor result (grade 4) according to the rating system of Good et al. The mean score (and standard deviation) on the ankle-hindfoot scale of the American Orthopaedic Foot and Ankle Society for the twenty-eight ankles that were examined directly by one of us was 90 +/- 9.3 points (range, 68 to 100 points). Progression of an exostosis at the edge of the joint was detected in eighteen (69 percent) of the twenty-six ankles that were examined radiographically, but narrowing of the joint space was not seen in any ankle. No relationship was detected between the clinical results and radiographic osteoarthrotic changes or the duration of follow-up. The results did not deteriorate over the long term.     

The deformation of beams structured by thin walls

Nowadays our society demands the reuse of industrial products. Then we should not only re-investigate the materials of products but also originate a new design method of industrial products. We have investigated the cellular structure by using abandoned paper, because the cell's shape can be proposed arbitrarily by folding a paper. As examples, we have proposed the structure constructed by connecting many folded cells formed in a hexagonal cross area. This structure will have characteristics such as almost high rigidity, high stiffness, crushing stress, relative insensitivity to the overall loss of stability. To estimate the characteristics of these structures, we must analyze the deformation in loading. When the structure with thin walls formed by paper is loaded, the shape of deformation is different from that of the metal, wall swells and does not maintain its flatness. Therefore, we cannot apply the traditional theory of elasticity for the analysis. In this paper, we propose a new estimation method by analyzing the swelling.     

The relationship between cell proliferation activity and secretory activity in pituitary adenoma--a review of 63 cases

Determination of the cell proliferation activity of neoplasm is useful in making a prognosis. Immunohistochemical detection using MIB-1 monoclonal antibody has recently allowed us to assess tumor cell proliferation easily, because it can be performed on paraffin-embedded specimens and the results have been demonstrated to be positively correlated with the results of PCNA staining. In this study, surgical specimens of 63 pituitary adenomas were examined by immunohistochemical staining with MIB-1 monoclonal antibody. Twenty-nine cases were non-functioning pituitary adenomas, 20 were prolactin (PRL)-producing pituitary adenomas, and 14 were growth hormone (GH)-producing pituitary adenomas. The MIB-1 positive rates of the pituitary adenomas ranged from 0% to 6.46%. In the non-functioning pituitary adenomas, the MIB-1 positive rates ranged from 0% to 4.55% (mean : 0.76%), in the PRL-producing pituitary adenomas the MIB-1 positive rates ranged 0% to 6.46% (mean : 0.91%), and in the GH-producing pituitary adenomas the MIB-1 positive rates ranged 0% to 1.28% (mean: 0.58%). There were no significant differences between these values according to the results of the Wilcoxon signed-rank test. Although the size of the non-functioning pituitary adenomas was not correlated with their MIB-1 positive rate, tumor size was closely correlated with the interval between the onset of the initial symptoms and the date of surgery. In the PRL-producing pituitary adenomas, the MIB-1 positive rate was not correlated with serum PRL levels as an index of secretory activity, but was correlated with the PRL staining positive rate. Preoperative bromocriptine therapy proved effective in reducing tumor size and serum PRL levels, but had no effect on the MIB-1 positive rate. In the GH-producing pituitary adenomas, the MIB-1 positive rate was not correlated with serum GH levels as an index of secretory activity, but was closely correlated with the GH staining positive rate. All three groups included both invasive and noninvasive tumor types, but there were no close statistical correlations between the three tumor types.