The Multiphase Flow CFD Analysis in Journal Bearings Considering Surface Tension and Oil-Filler Port Flow

This chapter presents the multiphase computational fluid dynamics (CFD) analysis on oil-lubricated high-speed journal bearings considering the oil-filler port. Journal bearings are widely used for high-speed rotating machinery such as turbines, compressors, pumps, automobiles, and so on. They can support the rotating shaft utilizing the oil lubrication film wedge effects used in the bearing clearance. Previously, in the analysis of journal bearings, which clearance is very narrow compared with shaft diameter, the Reynolds equation has been used on journal bearing analysis because of its applicability on the narrow space calculation and its low calculation cost. However, the gaseous-phase area generated in the journal bearing and the effect of oil-filler port cannot be reproduced accurately using the method. Under these backgrounds, some researchers use the CFD analysis to calculate the journal bearing characteristics in recent years. In this chapter, the authors describe the multiphase flow CFD analysis on journal bearing based on our previous studies . At first, the multiphase CFD calculation model on journal bearing and the experimental method are explained. Then, four types of calculation results under flooded and starved lubrication conditions are compared to the experimental ones. Additionally, the effect of surface tension on journal bearing characteristics is discussed. Finally, the CFD thermal analysis results under two types of supply oil conditions are shown

Measurements of Film Thickness and Pressure Distribution for Optimized Thrust Air Bearing

In this paper, we describe the film thickness and pressure measurement of the optimized thrust air bearing. In our recent study, a new optimization technique of the bearing groove geometry of the hydrodynamic thrust air bearings was proposed and a new groove geometry having a bending curve in outer vicinity of the bearing surface was obtained. Furthermore, in this study, the drastic improvement of the bearing dynamic stiffness was verified by the dynamic characteristic experiment using the original high-speed bearing test rig. However the relative error of the film thickness between the theory and experiment is large compared with that of dynamic stiffness. Consequently, it has been considered that the improvement of the measurement accuracy for film thickness is one of the most important problems. On the other hand, the generation of the negative pressure on the optimized bearing surface has not been confirmed experimentally, and it is also important to verify the negative pressure generation by measurement. Therefore, in this study, we examined the improvement of the measurement accuracy of the film thickness and the pressure measurement of the optimized bearing. As a result, the accuracy of air film thickness is drastically improved applying a newly proposed compensation method and the negative pressure on the optimized bearing can be found experimentally

Prognosis and long-term neurodevelopmental outcome in conservatively treated twin-to-twin transfusion syndrome

<p>Abstract</p> <p>Background</p> <p>Amnioreduction remains a treatment option for pregnancies with twin-to-twin transfusion syndrome (TTTS) not meeting criteria for laser surgery or those in which it is not feasible. Amnioreduction is a relatively simple treatment which does not require sophisticated technical equipment. Previous reports of conservative management have indicated that major neurodevelopmental impairment occurs in 14.3-26% of survivors. The purpose of this study was to investigate long-term neurodevelopmental outcome in conservatively treated TTTS.</p> <p>Methods</p> <p>During the nine-year study period from January 1996 to December 2004, all pregnancies with TTTS who were admitted to our center were investigated. TTTS was diagnosed by using standard prenatal ultrasound criteria, and staged according to the criteria of Quintero <it>et al</it>. We reviewed gestational age at diagnosis, gestational age at delivery, the stage of TTTS at diagnosis, and diagnosis to delivery interval. Neonatal cranial ultrasound findings were reviewed and the neurodevelopmental outcomes were evaluated.</p> <p>Results</p> <p>Twenty-one pregnancies with TTTS were included. Thirteen pregnancies (62%) were treated with serial amnioreduction. The mean gestational age at delivery was 28 weeks (22 - 34 weeks). The perinatal mortality rate was 42.9%. Twenty survivors were followed up until at least 3 years of age. The mean age at follow-up was 6.3 years (3 - 12 years). Six children (30%) had neurodevelopmental impairment. Four children (20%) had major neurodevelopmental impairment and two children (10%) had minor neurodevelopmental impairment. Children with neurodevelopmental impairment were delivered before 29 weeks of gestation.</p> <p>Conclusions</p> <p>Our study showed a high rate of perinatal mortality and a high rate of major neurodevelopmental impairment in conservatively treated TTTS. The long-term outcomes for the survivors with TTTS were good when survivors were delivered after 29 weeks of gestation.</p

Molecular phylogeny and evolution of alcohol dehydrogenase (Adh) genes in legumes

BACKGROUND: Nuclear genes determine the vast range of phenotypes that are responsible for the adaptive abilities of organisms in nature. Nevertheless, the evolutionary processes that generate the structures and functions of nuclear genes are only now be coming understood. The aim of our study is to isolate the alcohol dehydrogenase (Adh) genes in two distantly related legumes, and use these sequences to examine the molecular evolutionary history of this nuclear gene. RESULTS: We isolated the expressed Adh genes from two species of legumes, Sophora flavescens Ait. and Wisteria floribunda DC., by a RT-PCR based approach and found a new Adh locus in addition to homologues of the Adh genes found previously in legumes. To examine the evolution of these genes, we compared the species and gene trees and found gene duplication of the Adh loci in the legumes occurred as an ancient event. CONCLUSION: This is the first report revealing that some legume species have at least two Adh gene loci belonging to separate clades. Phylogenetic analyses suggest that these genes resulted from relatively ancient duplication events

The Inhibitory Effect of Kakkonto, Japanese Traditional (Kampo) Medicine, on Brain Penetration of Oseltamivir Carboxylate in Mice with Reduced Blood-Brain Barrier Function

Oseltamivir phosphate (OP) is used to treat influenza virus infections. However, its use may result in central nervous system (CNS) adverse effects. In Japan, OP is used with Kampo formulations to improve clinical effectiveness. We evaluated the potential for using Kampo formulations to reduce CNS adverse effects by quantifying the CNS distribution of oseltamivir and its active metabolite oseltamivir carboxylate (OC) when administered with maoto and kakkonto. We administered lipopolysaccharide (LPS) by intraperitoneal injection to C57BL/6 mice to reduce blood-brain barrier function. Saline, maoto, and kakkonto were administered orally at the same time as LPS. OP was orally administered 4 hours after the last LPS injection and the migration of oseltamivir and OC was examined. Additionally, we examined the brain distribution of OC following intravenous administration. Changes in OC concentrations in the brain suggest that, in comparison to LPS-treated control mice, both Kampo formulations increased plasma levels of OC, thereby enhancing its therapeutic effect. Additionally, our findings suggest kakkonto may not only improve the therapeutic effect of oseltamivir but also reduce the risk of CNS-based adverse effects. Considering these findings, it should be noted that administration of kakkonto during periods of inflammation has led to increased OAT3 expression

Conceptual design of DEMO blanket materials test modules for A-FNS

A conceptual design of Advanced Fusion Neutron Source, A-FNS, has been conducted to achieve early realization of fusion-like neutron irradiation test for fusion reactor materials in Japan. A-FNS provides eight test modules to obtain irradiation data for fusion reactor materials. Conceptual design activities on Blanket Functional Materials Test Module (BFMTM), Tritium Release Test Module (TRTM) and Activated Corrosion Products Module (ACPM) were described among the A-FNS test modules. Also, basic concepts of the sub-system cells for the TRTM and the ACPM were also discussed

Clinicopathologtcal Study of Serrated Polyps of the Colorectum, with Special Reference to Maspin Expression

Aims: We compared the clinicopathologic features of three types of colorectal serrated polyps, namely, hyperplastic polyps (HPs), sessile serrated adenomas/polyps (SSA/Ps), and traditional serrated adenomas (TSAs), and analyzed the expression pattern of maspin in these serrated lesions. We retrospectively examined 173 polypoid lesions that were endoscopically excised from 136 patients and diagnosed as hyperplastic or adenomatous serrated lesions, and histologically classified as HPs, SSA/Ps, or TSAs. Maspin expression was immunohistochemically examined in all lesions. Overall, 59 lesions (34%) were classified as HPs, 70 (40%) as SSA/Ps and 44 (25%) as TSAs. There were no significant differences in mean age or gender of patients between types, but SSA/Ps frequently developed on the right colon and showed a superficial/flat elevation, whereas HPs and TSAs frequently developed on the left colon and showed protruded lesions. The average diameters of HPs, SSA/Ps, and TSAs were 7.2, 9.9, and 12.9mm, respectively, showing significant differences. Diffuse cytoplasmic expression of maspin was observed in the serrated glands of all three types. In addition, focal or diffuse intranuclear localization of maspin was observed in 15% of HPs, 13% of SSA/Ps, and 84% of TSAs, showing significant differences between TSAs and the other two types. The three types of serrated polyp examined in this study showed distinct clinicopathological features. The presence of maspin expression in these polyps, regardless of whether they were hyperplastic or neoplastic, indicates that maspin might be commonly associated with cell proliferation, although the underlying mechanism might be different between types

Existence of a Neuropathic Pain Component in Patients with Osteoarthritis of the Knee

∙ The authors have no financial conflicts of interest. © Copyright: Yonsei University College of Medicine 2012 This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial Licens