23,820 research outputs found
Involvement of the AIM-KIM-1 axis in the repair process of lethal AKI.
No full text(A) Kaplan-Meier survival curves. Wild-type and HS-IR KIM-1−/− mice with or without rAIM injection (200 μg). n = 8 for KIM-1−/− mice; and n = 8 for rAIM-injected KIM-1−/− mice. IR without HS (n = 6) is also presented. Arrowheads indicate the times of rAIM injection. Statistics: log-rank test. (B) Representative photomicrographs of PAS-stained kidney specimens. The kidney images including the corticomedullary junction area from wild-type (KIM-1+/+) mice and HS-IR KIM-1−/− mice with or without rAIM injection on day 3 after IR (n = 3 each) are presented. (C) ATN scores on day 3 after IR. n = 4 each. Statistics: Welch’s t-test. (D) Serum IS levels. Values on day 3 after HS-IR. n = 6 for KIM-1−/− mice; and n = 5 for rAIM-injected KIM-1−/− mice. IR without HS (n = 6) are presented. Statistics: Welch’s t-test.</p
YIELD AND DENSIFICATION BEHAVIOR OF RAPIDLY SOLIDIFIED MAGNESIUM POWDERS
No full textIn order to obtain high-quality products in powder metallurgy, it is important to control and understand the densification behavior of metallic powders. The effect of the powder characteristics of magnesium powders on the compaction behavior was investigated in this study by experimental and theoretical methods. A modified version of Lee-Kim's plastic yield criterion, known as the critical relative density model, was applied to simulate the densification behavior of magnesium powders, and a new approach that extracts both the powder and the matrix characteristics was developed. The model was implemented via the finite element method, and powder compaction under upsetting conditions was simulated. The calculated and experimental results are in good agreement.X112Nscopu
Optical frequency-domain reflectometry based on wavelength-swept mode-locked fiber laser
No full textWe demonstrate a novel optical frequency-domain reflectometry system with compactness and short measurement time based on the use of a wavelength-swept mode-locked fiber laser. The optical source uses an intracavity tunable Fabry-Perot filter as a tuning element. The fiber laser sweeps 20 nm in less than 10 ms. Spatial resolution of 100 pm and total measurement range of several centimeters are demonstrated.The authors would like to thank Dr. H. K. Kim and Dr. S. H.
Yun for support and valuable discussions
Hepatitis C virus genotypes in Korea and their relationship to clinical outcome in type C chronic liver diseases.
No full textOBJECTIVES: The relationship between HCV genotype and the development of more serious liver disease has not been clearly established. This study was to investigate the distribution pattern of HCV genotypes in Korea and their relationship to the viremic level and to progression of chronic liver disease. METHODS: Study population was 217 patients with type C chronic liver disease. They were divided into 4 groups; 83 patients with near-normal ALT (group 1), 64 patients with elevated ALT (group 2), 20 patients with decompensated liver cirrhosis (group 3) and 50 patients with hepatocellular carcinoma (group 4). HCV genotypes were determined by reverse transcription polymerase chain reaction (RT-PCR) using mixed primer sets, and then the fidelity of genotyping was confirmed by cloning and sequencing. HCV RNA concentration was measured by quantitative competitive RT-PCR for 23 patients in group 2. RESULTS: The genotypes could be determined in 166 (76%) out of 217 patients. Type 1b and type 2a were predominantly occurring over the other types in somewhat similar frequency (45% and 51%, respectively). The genotype distribution of type 1b and 2a among four different groups showed 42% and 54% in group 1, 49% and 45% in group 2, 53% and 47% in group 3 and 41% and 57% in group 4; thus there was no significant difference in genotype distribution among 4 different disease groups. However, the viremia levels in patients with genotype 1b infection were significantly higher than those with genotype 2a. CONCLUSION: Genotype 2a infection is as prevalent as genotype 1b in Korea, and genotype 2a infection may pose no less risk for progression of disease despite lower replication level than genotype lb infection
Analysis of thermal behavior during equal channel multi-angular pressing by the 3-dimensional finite volume method
No full textThermal behavior and heat transfer during equal channel multi-angular pressing process of AZ31 alloy at room temperature were analyzed by using the 3-dimensional finite volume method. The simulations were carried out at different frictional conditions (friction factor m = 0, 0.1 and 0.2), pressing speeds (v = 2 and 20 mm/s), and pressing routes (A, B and C). The pressing speed influences more on the temperature rise of the AZ31 sample than the pressing route and friction condition. The initial temperature 293 K of the AZ31 alloy was increased up to 395 K for 20 mm/s pressing speed during the pressing. (c) 2008 Elsevier B.V. All rights reserved.X1111sciescopu
Densitication modelling for nanocrystalline metallic powders
No full textA model for densification of metallic powders is proposed. It involves viscoplastic constitutive equations based on dislocation density evolution and also accounts for effects of porosity using a pressure-dependent critical density yield criterion. The model was applied to the case of cold compaction of nanocrystalline copper under uniaxial compression conditions. Densification behaviour during powder compaction was simulated using an explicit integration method as applied to the dislocation density evolution and the variation of the relative density of the compact. The model was gauged by comparing the experimental data generated by cylindrical die compaction tests on Cu powder with the simulation results. The model accounts for the grain size and the deformation rate dependence on the densification process. The proposed densification model was implemented into a finite element code. The finite element method was applied to simulating room temperature die compaction of nanocrystalline Cu powder in order to investigate the densification behaviour. (C) 2003 Elsevier B.V. All rights reserved.X111112sciescopu
MULTI-SCALE FINITE ELEMENT SIMULATION OF SEVERE PLASTIC DEFORMATION
No full textThe technique of severe plastic deformation (SPD) enables one to produce metals and alloys with an ultrafine grain size of about 100 nm and less. As the mechanical properties of such ultrafine grained materials are governed by the plastic deformation during the SPD process, the understanding of the stress and strain development in a workpiece is very important for optimizing the SPD process design and for microstructural control. The objectives of this work is to present a constitutive model based on the dislocation density and dislocation cell evolution for large plastic strains as applied to equal channel angular pressing (ECAP). This paper briefly introduces the constitutive model and presents the results obtained with this model for ECAP by the finite element method.X11sciescopu
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