Effects of Particle Strength of Feedstock Powders on Properties of Warm-Sprayed WC-Co Coatings

Warm spray (WS) process, which can control the temperature of a combustion gas jet used to propel powder, has been successfully applied to deposit WC-Co coatings. Detrimental reactions resulting from dissolution of WC into Co binder and decarburization were suppressed effectively by keeping the WC-Co particles’ temperature below the m.p. of the binder phase. In this study, three nano-structured WC-12Co powders with different particle strengths were prepared by changing the sintering conditions of spray-dried powder and were deposited by WS. The deposition efficiency and porosity of the coatings decreased with increasing the particle strength. The coating deposited from the powder with very low particle strength showed significant phase changes, while those deposited from the higher particle strengths showed almost no change. Particle Image Velocimetry revealed significant disintegration of the weakest powder, which explains the changes observed. The hardness and wear properties of the former coating, therefore, were inferior to the other two.     

Enhanced osteoblast and osteoclast responses to a thin film sputtered hydroxyapatite coating

A sputtering technique followed by a low temperature hydrothermal treatment has been demonstrated to produce a dense-and-bioactive hydroxyapatite thin film coating. The purpose of the present study was to investigate osteoblast and osteoclast responses to the hydroxyapatite coated plates and titanium plates with similar roughness. Rat bone marrow stromal cells were cultured on these plates to induce osteoblasts. The cells showed a significantly enhanced proliferation on the hydroxyapatite surface, accompanied by increase of osteoblastic phenotypes. The co-cultured osteoclasts exhibited the significantly different cell number and morphology between the hydroxyapatite and the titanium surfaces. A series of osteoclast marker genes were more stimulated on the hydroxyapatite and thirty two percent of the hydroxyapatite surface area could be resorbed by osteoclasts. The thin film sputtered hydroxyapatite could provide a favorable surface for both osteoblast and osteoclast formation and their function, indicating its good osteoconductivity and biodegradability.     

Crack growth characteristics of carbon nanotube-based polymer composites subjected to cyclic loading

This paper presents the characterization of crack growth in carbon nanotube (CNT)-based polymer composites under fatigue loading. Fatigue crack growth tests were performed on single-edge cracked plate specimens of CNT/polycarbonate composites at room temperature and liquid nitrogen temperature (77 K). An elastic–plastic finite element analysis was also conducted to determine the J-integral range. The crack growth rate data were expressed in terms of the J-integral range, and the effect of nanotube addition on the fatigue crack growth behavior was examined. In addition, possible mechanisms of the crack growth in the nanocomposites are discussed based on microscopic observations of the specimen fracture surfaces.     

Evidence for the existence of L-dopa-immunoreactive neurons in the human mesencephalic region

Radioactive end labeling can be used to determine the hydrolytic rates of nuclease mimics on moderate to long lengths of RNA or DNA. However, the reliability of end labeling as an assay can vary depending on how well the unincorporated label is removed from the labeled RNA or DNA products. Therefore, gel filtration, acid precipitation, membrane diafiltration, and paper chromatography were tested to determine which technique was the most effective at such separation. The results in order of decreasing contamination by [gamma-32P]ATP were gel filtration (40%), acid precipitation (5%), diafiltration (2%), and paper chromatography (1%); and, in order of decreasing loss of RNA, were acid precipitation (30%), diafiltration (11%), gel filtration (10%), and paper chromatography (1%). In order for the resultant radioactive counts to be linearly proportional to the number of cleavage sites, the total ATP in the end-labeling reaction should be in excess of 5'-hydroxyl ends by a factor of 10 or more. Interference by nuclease mimics in the end-labeling reaction should be accounted for by including the mimics when developing a standard curve based on known concentrations of 5'-hydroxyl ends.     

Charged amino acids at the carboxyl-terminal portions determine the intracellular locations of two isoforms of cytochrome b5

Outer mitochondrial membrane cytochrome b5 (OMb), which is an isoform of cytochrome b5 (cyt b5) in the endoplasmic reticulum, is a typical tail-anchored protein of the outer mitochondrial membrane. We cloned cDNA containing the complete amino acid sequence of OMb and found that the protein has no typical structural feature common to the mitochondrial targeting signal at the amino terminus. To identify the region responsible for the mitochondrial targeting of OMb, various mutated proteins were expressed in cultured mammalian cells, and the subcellular localization of the expressed proteins was analyzed. The deletion of more than 11 amino acid residues from the carboxyl-terminal end of OMb abolished the targeting of the protein to the mitochondria. When the carboxyl-terminal 10 amino acids of OMb were fused to the cyt b5 that was previously deleted in the corresponding 10 residues, the fused protein localized in the mitochondria, thereby indicating that the carboxyl-terminal 10 amino acid residues of OMb have sufficient information to transport OMb to the mitochondria. The replacement of either of the two positively charged residues within the carboxyl-terminal 10 amino acids by alanine resulted in the transport of the mutant proteins to the endoplasmic reticulum. The mutant cyt b5, in which the acidic amino acid in its carboxyl-terminal end was replaced by basic amino acid, could be transported to the mitochondria. It would thus seem that charged amino acids in the carboxyl-terminal portion of these proteins determine their locations in the cell.     

Urethral recurrence of bladder cancer 16 years after total cystectomy. A case report]

A 74-year-old man was admitted to our hospital. Diagnosis of invasive bladder cancer was made and a total cystectomy was performed on January, 30, 1980. Histological examination showed transitional cell carcinoma, grade 2, pT1 is N0M0. After 16 years, when he suffered left femur, he had right inguinal lymphnode swelling. On the biopsy of the inguinal mass, histology was transitional cell carcinoma. The urethral washing cytology was positive. Lung CT scan dem onstrated multiple lesions. He was diagnosed of the urethral recurrence, right inguinal lymphnode metastasis and lung metastasis of bladder cancer. This case is the 5th case of urethral recurrence of bladder cancer following cystectomy in our hospital.