Suppression of senescence in normal human fibroblasts by introduction of dominant-negative p53 mutants or human papilloma virus type 16 E6 protein

Transfection of nearly senesced human fibroblasts with plasmids encoding HPV16 E6 protein or dominant-negative p53 mutants greatly increased their colony-forming ability. Isolated colonies with these plasmids showed extension of lifespan compared to those with a control plasmid. These data demonstrate that p53 plays a major role in senescence in normal human fibroblasts.     

Detailed deletion mapping suggests the involvement of a tumor suppressor gene at 17p13.3, distal to p53, in the pathogenesis of lung cancers

The short arm of chromosome 17 is one of the most frequently affected chromosomal regions in lung cancers, while there is solid evidence that the p53 gene at 17p13.1 is a target for frequent 17p deletions. In the present study, we re-evaluated 17p deletions in lung cancers by conducting a detailed analysis of the minimum deleted region(s) on 17p with reference to the p53 gene status in each 100 primary lung cancer cases. In addition to the p53 locus at 17p13.1, the presence of an independent, commonly deleted region(s) at 17p13.3 was identified. Furthermore, loss of heterozygosity (LOH) at 17p13.3 was shown to be even more frequent than that at 17p13.1 and it appeared to occur in the absence of p53 mutation and/or 17p13.1 deletion. These results suggest that in addition to the p53 gene at 17p13.1, an as yet unidentified tumor suppressor gene(s) residing at 17p13.3 might play a role in lung carcinogenesis possibly in an earlier phase than the p53 gene. This would warrant future studies to identify the putative tumor suppressor gene at 17p13.3 in order to gain a better understanding of the molecular pathogenesis of this fatal disease.     

Laser-irradiation effect on poly(vinyl alcohol) films doped with nanometer-sized CdS particles: Ablation and third-harmonic generation

Ultrasmall CdS particles, whose average size was controlled by thiols to range from 2 to 4 nm, were embedded in poly(vinyl alcohol) films. Shift of the fluorescence peak associates with the shift of the absorption threshold of the films, and the fluorescence intensity increases with the decrease in the size of CdS. Laser ablation at 308 nm was investigated by monitoring the emission spectra. Third-harmonic generation was measured for various sizes of CdS particles, and the optical nonlinearity in the nonresonance region was found to remain almost constant in the diameter range studied. © 1993 John Wiley & Sons, Inc.     

Surface and bulk-passivated large area multicrystalline silicon solar cells

We have investigated the surface and bulk passivation technique on large-area multicrystalline silicon solar cells, a large open-circuit voltage has been obtained for cells oxidized to passivate the surface and hydrogen annealed after deposition of silicon nitride film on both surfaces by plasma CVD method (P---SiN) to passivate the bulk. The texture surface like pyramid structure on multicrystalline silicon surface has been obtained uniformly using reactive ion etching (RIE) method. Combining these RIE method and passivation schemes, the conversion efficiency of 17.1% is obtained on 15 cm × 15 cm multicrystalline silicon solar cell. Phosphorus diffusion, BSF formation, passivation technique and contact metallization for low-cost process sequence are also described in this paper.     

Structural and electrochemical properties of LiNi1/3Co1/3Mn1/3O2: Calcination temperature dependence

The structure of the layered LiNi_1/3Co_1/3Mn_1/3O₂ has been investigated by powder X-ray diffraction and electron diffraction, and the relationship of the calcination temperature with the crystal structure, morphology and electrochemical properties has been studied. All the unit cell parameters increase monotonically with increasing the calcination temperature. Some of the [00.1] zone electron diffraction patterns for the sample calcined at higher temperature than 1000 °C show extra spots indicating the 2 × 2 ordering in the basal triangular lattice. These results indicate that the high temperature calcination leads to the formation of vacancies in the transition metal layers with the spinel-like ordering. The calcination at higher temperature lowers the specific capacities and degrades the cycle performances, while the packing density of the powder is increased by the sintering. The optimum calcination temperature is 900 °C in order to obtain the electrochemically active and dense packed oxide particles. The decrease of Li composition leads to coprecipitation of the spinel-like second phase in the range of 0.742 ≤ x ≤ 0.884 for Li_xNi_1/3Co_1/3Mn_1/3O₂, when calcined at 900 °C. The Li-deficient samples show the worse electrochemical properties similarly to the stoichiometric samples calcined at high temperature. For the Li-excess samples, no impurity phase has been detected and their cycle performances are improved.     

Magnetic proximity effect as a pathway to spintronic applications of topological insulators

Spin-based electronics in topological insulators (TIs) is favored by the long spin coherence(1,2) and consequently fault-tolerant information storage. Magnetically doped TIs are ferromagnetic up to 13 K,(3) well below any practical operating condition. Here we demonstrate that the long-range ferromagnetism at ambient temperature can be induced in Bi(2-x)Mn(x)Te(3) by the magnetic proximity effect through deposited Fe overlayer. This result opens a new path to interface-controlled ferromagnetism in TI-based spintronic devices.     

Electroactive microwell arrays for highly efficient single-cell trapping and analysis

We present a novel method, implemented in the form of a microfluidic device, for arraying and analyzing large populations of single cells. The device contains a large array of electroactive microwells where manipulation and analysis of large population of cells are carried out. On the device, single cells can be actively trapped in the microwells by dielectrophoresis (DEP) and then lysed by electroporation (EP) for subsequent analysis of the confined cell lysates. The DEP force in the selected dimensions of the microwells could achieve efficient trapping in nearly all the microwells (95%) in less than three minutes. Moreover, the positions of the cells in the microwells are maintained even when unstable flow of liquid is applied. This makes it possible to exchange the DEP buffer to a solution that will be subsequently used for stimulating or analyzing the trapped cells. After closing the microwells, EP is conducted to lyse the trapped cells by applying short electric pulses. Tight enclosure is critical to prevent dilution, diffusion and cross contamination of the cell lysates. We demonstrated the feasibility of our approach with an enzymatic assay measuring the intracellular-galactosidase activity. The use of this method should greatly help analysis of large populations of cells at the single-cell level. Furthermore, the method offers rapidity in the trapping and analysis of multiple cell types in physiological conditions that will be important to ensure the relevance of single cell analyses.     

Grain boundary engineering of titanium-stabilized 321 austenitic stainless steel

Grain boundary engineering (GBE) primarily aims to prevent the initiation and propagation of intergranular degradation along grain boundaries by frequent introduction of coincidence site lattice (CSL) boundaries into the grain boundary networks in materials. It has been reported that GBE is effective to prevent intergranular corrosion due to sensitization in unstabilized 304 and 316 austenitic stainless steels, but the effect of GBE on intergranular corrosion in stabilized austenitic stainless steels has not been clarified. In this study, a twin-induced GBE utilizing optimized thermomechanical processing with small pre-strain and subsequent annealing was applied to introduce very high frequencies of CSL boundaries into a titanium-stabilized 321 austenitic stainless steel. The resulting steel showed much higher resistance to intergranular corrosion after sensitization subsequent to carbon re-dissolution heat treatment during the ferric sulfate–sulfuric acid test than the as-received one. The high CSL frequency resulted in a very low percolation probability of random boundary networks in the over-threshold region and remarkable suppression of intergranular corrosion during GBE.