Prediction of gas‐liquid two‐phase mixture flow in a vertical pipe with a sudden expansion in diameter

The principle of gas‐lift pumps is applied to vacuum‐decarburization with the RH (Ruhrstahl Heraeus) process to circulate molten steel. Gas‐lift pumps are also applicable to the transportation of molten iron/steel between different refining processes. This paper treats theoretical analysis of steady‐state flow characteristics of gas‐liquid two‐phase mixtures rising in a vertical pipe with an abrupt expansion of its diameter. The system of governing equations is based upon a one‐dimensional multi‐fluid model. Flow pattern transitions are taken into consideration. A new numerical procedure to predict the flow characteristics at the sudden expansion has been proposed. Experiments have also been performed for several conditions to confirm the applicability as well as the validity of the present numerical model. It has been found that the predictions agree reasonably well with the experimental data. Next, the effect of the sudden expansion of pipe diameter on the pump performance was investigated numerically. As a result, it has been confirmed that the sudden expansion of pipe diameter contributes to improve the pump efficiency.     

Preparation of diamond whiskers using Ar/O2 plasma etching

Radio frequency (RF) plasma etching of chemical vapor deposition (CVD) diamond film has been investigated in Ar/O₂ plasmas, with an emphasis to elucidate the effects of reacting gas on the fabrication of diamond whiskers. Diamond whiskers were formed on diamond films pre-coated with Al. It was found that diamond whiskers preferentially formed at the diamond grain boundaries. The densities of diamond whiskers increased with O₂ / Ar ratio. Whiskers obtained in pure O₂ plasma etching were 50 nm in diameter and 1 μm in height. The etching rate was increased by mixing Ar with appropriate volume of O₂. Al coated on the diamond surface reacted with O₂ to form Al₂O₃, serving as mask to restrain the etching underneath. Raman spectroscopy measurement confirmed that the whiskers kept sp³ diamond bonding structure after RF plasma etching. The field emission characteristics of the whiskers were also inspected.     

Effects of ondansetron on electrically evoked contraction in rat stomach fundus: possible involvement of 5-HT2B receptors

The effect of dietary RRR-gamma-tocopherol supplementation on serum and tissue alpha- and gamma-tocopherol concentrations was studied in vitamin-E-deficient rats fed diets containing adequate levels of RRR-alpha-tocopherol and graded levels of RRR-gamma-tocopherol over a 60 day period. Feeding rats with a RRR-alpha-tocopherol-supplemented diet induced in forebrain, sciatic endoneurium, skeletal muscle, heart and liver a marked increase in alpha-tocopherol concentration. In contrast, feeding rats with a diet containing the same level of RRR-gamma-tocopherol induced a small increase in gamma-tocopherol concentrations in brain, sciatic endoneurium, skeletal, muscle, heart and liver and a slight but significant decrease in alpha-tocopherol concentration in all tissues examined. In rats fed diets containing a constant level of RRR-alpha-tocopherol and graded levels of RRR-gamma-tocopherol, the concentrations of alpha-tocopherol in all tissues were much higher than those in rats fed a control diet containing RRR-alpha-tocopherol alone. The higher the gamma/alpha ratio, the more the alpha-tocopherol concentrations increased. Significant positive linear regressions were found between the gamma/alpha ratio and the alpha- and gamma-tocopherol concentrations in most of the tissues examined. These results indicate that when gamma-tocopherol was supplied continuously in the diet gamma-tocopherol accumulated significantly in the tissues but to a much smaller extent than when rats were fed with RRR-alpha-tocopherol. These experiments also indicate that gamma-tocopherol did not depress the serum and tissue alpha-tocopherol concentrations. On the contrary, gamma-tocopherol supplements induced a marked increase in alpha-tocopherol concentrations in the serum and tissues. These results suggest that there is a relationship between alpha- and gamma-tocopherol levels in vivo and that the biopotency of alpha-tocopherol should be reevaluated especially when high levels of gamma-tocopherol were present in the diet.     

Nineteen multiple primary cancer cases of 100 patients undergoing lung cancer resection

In our department, half of 100 consecutive lung cancer resection cases were over the age of 70 years. In the same 100 patients, nineteen cases had multiple primary cancers. Sixteen cases had double, two cases had triple, one case had quadruple primary cancers. The incidence rate of multiple primary cancers involving the lung was 19%. This incidence of 19% is higher than the others ever reported in Japan. It was concluded, when lung cancer patients were elder, that there was increasment in the frequency of multiple cancer cases involving lung, and there was a high possibility of the occurrence of 2nd and 3rd primary cancers.     

Tensile Strength and Deformation of a Two-Dimensional Carbon–Carbon Composite at Elevated Temperatures

Tensile strength and creep behavior of a two-dimensional (2D) laminate carbon–carbon composite (C/C) were examined from room temperature to 2773 K in an inert atmosphere. The tensile strength of the C/C was monotonically enhanced with increasing test temperatures. In particular, significant improvement was observed at temperatures higher than 1773 K. In this temperature range, nonlinear stress–strain curves were observed at low deformation rates, but with increasing test speed, the stress–strain curves became linear until total fracture. The source of the apparent nonlinearity was thus concluded to be creep deformation, which appeared from 1773 K. Two ruling mechanisms for the strength enhancement of the C/C at elevated temperatures were identified. The first source was degassing of absorbed water, which had a dominant influence on the strength enhancement up to 1773 K. The second was creep deformation. This phenomenon was notable at temperatures higher than 1773 K, and produced much larger enhancement than the degassing.     

Inhibition of influenza virus replication by phosphorothioate and liposomally endocapsulated oligonucleotides

We have demonstrated that antisense phosphorothioate oligonucleotides (S-ODNs) inhibit influenza virus A replication in MDCK cells. Phosphorothioate and liposomally encapsulated oligonucleotides with two target sites (PB1 and PB2) were synthesized and tested for virus-induced cytopathogenicity effects by a MTT assay using MDCK cells. The liposomally encapsulated S-ODNs complementary to the sites of the PB2-AUG initiation codon showed highly inhibitory effects. On the other hand, the inhibitory effect of the liposomally encapsulated S-ODNs targeted to PB1 was considerably decreased in comparison with the PB2 target sites. The liposomally encapsulated oligonucleotides exhibited higher inhibitory activity than the free oligonucleotides. The activities of the modified oligonucleotides are effectively enhanced by using the liposomal carrier.     

Alteration of tubulin-Gi protein interaction in rat cerebral cortex with aging

The ability of the tubulin dimer to interact with and to modulate the Gi function inhibiting adenylyl cyclase was examined in cerebral cortex membranes from 2-month-old and 24-month-old rats. The hydrolysis-resistant GTP analogue 5'-guanylylimidodiphosphate (GppNHp)-dependent inhibition of adenylyl cyclase was significantly decreased in cerebral cortex membranes from 24-month-old rats. Tubulin, prepared from rat brains by polymerization with GppNHp, caused inhibition of adenylyl cyclase (approximately 28%) in 2-month-old rats. Tubulin-GppNHp-dependent inhibition of adenylyl cyclase in 24-month-old rats was significantly attenuated (approximately 15%). In 2-month-old rats, when tubulin, polymerized with the hydrolysis-resistant photoaffinity GTP analogue [32P]P3(4-azidoanilido)-P1-5'-GTP ([32P]AAGTP), was incubated with cerebral cortex membranes, AAGTP was transferred from tubulin to Gi alpha. Transfer of AAGTP from tubulin to Gi alpha was reduced in 24-month-old rats. Furthermore, photoaffinity labeling of [32P]AAGTP to Gi alpha in cortex membranes was significantly decreased in 24-month-old rats. No differences were observed in the amounts of Gs alpha, Gi alpha, or G beta subunits and tubulin, estimated by immunoblotting, in cortex membranes from 2-month-old and 24-month-old rats. These results suggest that the ability of tubulin to interact with Gi and thereby modulate the inhibitory regulation of adenylyl cyclase is reduced in the cerebral cortex of 24-month-old rats.