Changes in the gaseous H2S barrier properties of damaged silicate coated nylon 6 films

The damage imposed on SiO _x deposited nylon 6 films as a result of abrasion with a cotton cloth and Gelboflex testing was examined by evaluating the rate at which copper plates, which were enveloped by the damaged films, were corroded by H₂S. Abrasion with a cotton cloth caused some micro-cracking of the SiO _x layer and the permeation rate of H₂S approached that of the uncoated nylon 6 film. Damage to the SiO _x layer by twisting and crushing progressed gradually with the number of Gelboflex test cycles and correspondingly the corrosion rate of the copper plates increased. Comparison of the corrosion rates of the copper plates kept in the pouches made of various commercial films with those obtained for the damaged SiO _x deposited nylon 6 films showed a clear relationship between the H₂ permeation rate of the films and the corrosion rate of the copper plates by H₂S.     

Surface Hardening of Carbon Steel Using High Powered YAG Laser

A high powered YAG laser with kaleidoscope for surface modification was applied to the surface hardening of carbon steels containing 0. 18-0.54 wt% C without the absorbents, and the relationships between laser processing and surface hardening were investigated by hardness and microstructure. The structure of the hardened zone underwent complete martensitic transformation in all of the carbon steels tested, and its hardness increased with greater carbon content. Under identical irradiated conditions, the hardened zone expanded with increasing carbon content. A hardened zone extending from the surface to a depth of 1.0 mm was obtained at a laser power of 1.0 kW and a scanning speed of 1 mm/sec. It was found that in the surface hardening of carbon steels, a high powered YAG laser can be used to control the hardened zone by selecting the appropriate irradiation conditions, however, the hardened zone was affected by the assistant gas and the flow rate.     

Lifetime improvement of slackened thin cluster carbon stripper foils by suppression of carbon buildup

We control the amount of carbon buildup on slackened thin cluster carbon stripper foils (less than 3.5 μg/cm²) by heating with a high-power infrared lamp during beam bombardment. Foil lifetime measurements were performed using 2.0±0.5 μA beams of 3.2 MeV Ne⁺ ions and quantified as the total charge/area before breakage. Lifetimes were obtained up to 1286 mC/cm² at maximum and 1139 mC/cm² on the average; these values are, respectively, approximately 51 times at maximum and 46 times on average greater than the best commercially available foils, when used unheated and unslackened.     

Strain-mediated phase control and electrolyte-gating of electron-doped manganites

A prototype Mott transistor, the electric double layer transistor with a strained CaMnO(3) thin film, is fabricated. As predicted by the strain phase diagram of electron-doped manganite films, the device with the compressively strained CaMnO(3) exhibits an immense conductivity modulation upon applying a tiny gate voltage of 2 V.     

Stability of the ultrafine-grained microstructure in silver processed by ECAP and HPT

The high-temperature thermal stability of the ultrafine-grained (UFG) microstructures in low stacking fault energy silver was studied by differential scanning calorimetry (DSC). The UFG microstructures were achieved by equal-channel angular pressing (ECAP) and high-pressure torsion (HPT) at room temperature (RT). The defect structure in the as-processed samples was examined by electron microscopy and X-ray line profile analysis. The stored energy calculated from the defect densities was compared to the heat released during DSC. The sum of the energies stored in grain boundaries and dislocations in the ECAP-processed samples agreed with the heat released experimentally within the experimental error. The temperature of the DSC peak maximum decreased while the released heat increased with increasing numbers of ECAP passes. The released heat for the specimen processed by one revolution of HPT was much smaller than after 4–8 passes of ECAP despite the 2 times larger dislocation density measured by X-ray line profile analysis. This dichotomy was caused by the heterogeneous sandwich-like microstructure of the HPT-processed disk: about 175 μm wide surface layers on both sides of the disk exhibited a UFG microstructure while the internal part was recrystallized, thereby yielding a relatively small released heat.     

Microstructural evolution in high purity aluminum processed by ECAP

High purity (99.99%) aluminum was processed by equal-channel angular pressing (ECAP) through 1–12 passes and examined using orientation imaging microscopy. The results reveal two distinct processing regimes: from 1 to 4 passes the microstructure evolves from elongated subgrains to an essentially equiaxed array of ultrafine grains and from 4 to 12 passes there is no measurable change in the average grain size and grain aspect ratio. The boundary misorientation angle and the fraction of high-angle boundaries increase rapidly up to 4 passes and at a slower rate from 4 to 12 passes. Anomalously large grains were visible in the central region of the billet pressed through 12 passes due to dynamic recovery and grain growth. The results suggest optimum processing is achieved by pressing through 4–8 passes.     

Subsegmentectomy or segmentectomy in hepatocellular carcinoma

BACKGROUND/AIMS: We determined the optimal therapeutic strategy for improving survival in patients with hepatocellular carcinoma (HCC), based on an analysis of our surgical results. METHODOLOGY: Between January 1990 and December 1996, 205 patients underwent initial curative hepatectomy. The liver volume to be resected was decided according to the plasma retention of indocyanine green 15 minutes after injection. The appropriate subsegmental and segmental areas were disclosed by staining under ultrasonographic guidance. Limited resection or tumor enucleation was performed in 119 patients, subsegmentectomy or segmentectomy in 71, and lobectomy or extended lobectomy in 15. RESULTS: Intrahepatic recurrence was documented in 115 patients, 46 of whom died from cancer recurrence. Disease free survival was 65% after 1 year, 35.1% after 3 years and 25.3% after 5 years. The type of hepatectomy (limited vs. subsegmental or segmental resection) significantly affected the cumulative survival (p = 0.047) and disease free survival rates (p < 0.01). Among the 115 patients with recurrence, 22 patients underwent repeated hepatectomy combined with TAE (transcatheter arterial embolization) and the remainder underwent TAE alone. Patients who underwent repeated hepatectomy combined with TAE survived significantly longer after recurrence than those who underwent TAE alone (p = 0.0197). CONCLUSION: Initial subsegmentectomy or segmentectomy prolongs disease free survival, and patients eligible for repeated hepatectomy combined with TAE after recurrence have a good chance of long-term survival. Subsegementectomy or segmentectomy should be performed in a lot more HCC patients in order to improve survival.     

Involvement of R-cadherin in the early stage of glomerulogenesis

The earliest commitment to the formation of glomeruli is recognizable in S-shaped bodies. Although cell-cell adhesion seems likely to play a crucial role in this process, how glomerular epithelial cells segregate from the other parts of the nephron is unknown. In this study, immunofluorescence microscopy and monoclonal antibodies specific for mouse R-, E-, P- and N-cadherins were used to examine which of these adhesion molecules are involved in glomerulogenesis of the mouse kidney. Weak R-cadherin staining was first found in the vesicle stage, becoming restricted to glomerular visceral epithelial cells (VEC) during the S-shaped body stage. The intensity of this staining became stronger in the capillary loop stage, whereas parietal epithelial cells (PEC) and tubular cells did not stain. In the maturing stage, VEC gradually lost their staining for R-cadherin. E-cadherin was detected in ureteric buds and the upper limb of S-shaped bodies. From the capillary loop to the maturing stage, anti-E-cadherin stained epithelial cells in all tubule segments, but no label was seen in VEC or PEC. P-cadherin was also stained in the ureteric buds and in the upper limb of S-shaped bodies. N-Cadherin was weakly stained in cells at the vesicle stage, but thereafter staining of N-cadherin was not detected at any stage of glomerular formation. Immunoelectron microscopy of differentiating VEC was performed using antibodies specific to alpha-catenin, which is associated with cadherin. Subsequently, immunogold particles identifying alpha-catenin were localized on junctions between primary processes of VEC. These findings indicate that R-cadherin is uniquely expressed in differentiating VEC, suggesting an important role in the early stages of glomerulogenesis.