Characterization of Mechanical Properties and Grain Size of Stainless Steel 316L via Metal Powder Injection Molding.

The metal powder injection molding process is completed by mixing a metal powder and a binder, performing an injection molding and degreasing process, and then performing a sintering process for high density. The disadvantage of metal powder injection molding is that defects occurring during the process affect mechanical properties, which are worse in mechanical properties than in products manufactured by cold-rolling. In this study, the mechanical properties and microstructure of stainless steel 316L manufactured by the metal powder injection molding process were analyzed. Mechanical properties such as density, tensile strength, and fatigue life were analyzed. The density was measured using Archimedes' principle, and a relative density of 94.62% was achieved compared to the theoretical density. The tensile strength was approximately 539.42 MPa and the elongation to fracture was approximately 92%. The fatigue test was performed at 80% of maximum tensile strength and a stress ratio of R = 0.1. The fatigue life was found in 55% (297 MPa) of maximum tensile strength that achieved 106 cycles. The microstructure was observed through scanning electron microscope after etching, and as a result, the average grain size was 88.51 µm. Using electron backscatter diffraction, inverse pole figure map, image quality map, and kernel average misorientation map of the specimen were observed in three different areas which were undeformed, uniformly deformed, and deformed. Based on these results, it is expected that research is needed to apply the metal powder injection molding process to the manufacture of agricultural machinery parts with complex shapes.

Simultaneous bilateral stenosis of the vertebral arteries treated by unilateral decompression: a case report.

A 56-year-old man presented with a 3-month history of progressive dizziness. His dizziness was aggravated when his head was rotated to the right side. Diagnostic angiography showed that a normal right-sided vertebral artery in the neutral position became an abnormal vertebral artery with two stenotic lesions at the C3-4 and C5-6 levels when the patient's head was turned to the right. A normal left-sided vertebral artery also showed a stenotic lesion at the C2 level when the patient's head was turned right. The axial dimensions of the bilateral vertebral arteries were similar. The patient was successfully treated with decompression of only one level (C5-6). We conclude that if a bilateral stenosis is found upon one directional head rotation and the bilateral vertebral arteries are similarly sized, a one-sided treatment may suffice.

Distribution of viral RNA in mouse tissues during acute phase of coxsackievirus B5 infection.

OBJECTIVE: To investigate histopathological changes and distribution of coxsackievirus B5 (CVB5) RNA in mouse heart, liver, and pancreas during the acute phase of infection. METHODS: C3H/HeJ male mice, aged 3-4 weeks, were inoculated intraperitoneally with 5 x 10(5) plaque-forming units of CVB5 and sacrificed at 1, 2, 3, 4, 7 and 10 days postinfection (p.i.). Inflammation of the heart, liver, and pancreatic tissue sections was evaluated by hematoxylin and eosin staining, and virus was detected using antibody to viral coat protein VP1. A quantitative real-time RT-PCR method, using primers and probe targeted to the highly conserved sequences in the 5'-untranslated region of the virus, was used to evaluate the kinetics of CVB5 RNA during the development of myocarditis or pancreatitis. RESULTS: Marginal inflammatory changes were observed in the heart tissues although viral RNA was constantly present between 1 and 10 days p.i., peaking at 4 days p.i. The pancreatic tissues displayed massive lymphocyte infiltration and loss of acinar cells at day 4 p.i. and viral RNA was detected between 1 and 10 days p.i., peaking at 2-3 days p.i. In the liver, viral RNA was detected between 1 and 7 days. No mortality was observed. CONCLUSIONS: CVB5 induced acute pancreatitis without subsequent development of myocarditis. Clearance of CVB5 RNA from the pancreas and heart was slower than clearance from the liver. Our real-time RT-PCR method, which is more sensitive than conventional plaque assay, may provide valuable insight into viral RNA kinetics during CVB5 infection.