Fracture and deformation properties of Ni-Fe superalloy in cryogenic high magnetic field environments

The present paper includes experimental and analytical data on the fracture properties of a nickel-iron superalloy, a ferromagnetic austenite, at 4 K in magnetic fields of 0 and 6 T. The tensile, notch tensile and small punch tests are employed. A finite element analysis is also performed to convert the experimentally measured load-displacement data into useful engineering information. To interpret the results we review the available theory of the influence of magnetic field on the stress intensity factor for a crack in ferromagnetic materials.     

Nonlinear Optical Properties of TeO2-Based Glasses: MOx-TeO2 (M = Sc, Ti, V, Nb, Mo, Ta, and W) Binary Glasses

The third-order nonlinear optical susceptibilities, X⁽³⁾, of TeO₂-based glasses containing transition metal oxides (M = Sc₂O₃, TiO₂, V₂O₅, Nb₂O₅, MoO₃, Ta₂O₅, and WO₃) glasses have been measured by the third harmonic generation (THG) method in order to investigate the effect of the empty d-orbital contributions to the third-order nonlinear optical susceptibilities. It is found that the addition of TiO₂, Nb₂O₅, and WO₃ to TeO₂ glass increases the X⁽³⁾ value as well as the refractive index, while others decrease both of them. The positive effect of the TiO₂, Nb₂O₅, or WO₃, on the X⁽³⁾ of TeO₂ glass was interpreted in terms of the cationic empty d-orbital contribution. There is an almost linear relation between the X⁽³⁾ and the term (n²_ω+ 2)³.(n²_ω -1).E_d/E²₀ containing three measurable parameters only, irrespective of the kinds of MO, which was derived based on the bond orbital theory developed by M. E. Lines. The largest X⁽³⁾ value obtained is 1.69 × 10⁻¹² esu for 30NbO_2.5.70TeO₂ glass, about 60 times larger than that of pure fused silica glass.     

Photoelectrochemical properties of sol–gel-derived Ti1−xVxO2 solid solution film photoelectrodes

Ti_1−xV_xO₂ solid solution film photoelectrodes were prepared by the dip-coating sol–gel method. X-ray diffraction and X-ray photoelectron spectroscopy were employed to ensure the formation of the solid solution and their composition. Obvious photoresponses were observed in the visible region for the solid solution film electrodes with x0.05 and the red shift of the photoresponse was enhanced with increasing x. Moreover, the solid solution film electrodes were found to be photoelectrochemically stable. However, the onset potential of photocurrent shifted positively with increasing x. Band model of the solid solution was suggested to explain the effects of the vanadium incorporation on the photoelectrochemical properties.     

Silicon nitride thin-film deposition by LPCVD with in situ HF vaporcleaning and its application to stacked DRAM capacitor fabrication

Silicon nitride film deposited by LPCVD with newly developed in situ HF vapor cleaning has been studied and applied to fabricate dielectric films for stacked DRAM capacitors. Using this method, an oxide-free surface of underlaid poly-Si can be obtained. Silicon nitride film deposited on this surface has been verified by FTIR measurement to have the stoichiometrically proper composition of Si₃N₄ . However, the film was found to be selectively deposited on poly-Si electrodes. This selective deposition degrades the reliability of the stacked capacitor, because the silicon nitride can not completely cover the periphery of poly-Si electrodes on SiO₂. We propose a simple process that avoids the problem making it possible to apply silicon nitride film to stacked-capacitor fabrication. Stacked capacitors fabricated by this process exhibit very low leakage current and high electrical reliability even for ultra-thin silicon nitride films less than 5 nm thick     

Enhancement of adenovirus-mediated gene transfer to human bone marrow cells

Adenovirus infection of CD34+ hematopoietic stem/progenitor cells is dependent on the multiplicity of infection (MOI), time of incubation, the volume in which the co-incubation occurs and the presence or absence of growth factors. Studies revealed that a brief co-incubation (1-8 hours), resulted in low levels of transgene expression, suggesting that adenovirus infection of CD34+ cells occurs slowly, and optimal transduction requires a 24 hour exposure to adenovirus. Infection by Ad/beta-gal or Ad/p53 at a MOI of 500:1 provided a high transduction efficiency but inhibited hematopoietic function. However, treatment at a MOI of 50-100 resulted in efficient transduction (10.7-15.7% positive) without detectable toxicity. Secondary proof of adenovirus transgene expression was demonstrated by detection of mRNA for p53 in Ad/p53 infected stem cells. We conclude that a 24 hour exposure to recombinant adenovirus encoding p53 or beta-gal, at a MOI of 50-100 is optimal for in vitro gene transfer to BM cells and has no significant effect on hematopoietic function. Adenovirus-mediated transduction of BM cells can also be modulated by growth factors (IL-3, GM-CSF and G-CSF) with improved gene delivery and maintenance of hematopoietic function. In summary, adenovirus vectors can be used to transiently transduce stem cells, and conditions have been defined to maximize expression and limit inhibitory effects on CD34+ cells. These data support continued investigation of this vector for local cytokine delivery and purging of stem cell products.     

Preparation of multiple oxide BaTiO3 fibres by the sol-gel method

Multiple oxide BaTiO₃ gel fibres were prepared by the sol-gel method from Ba(OC₂H₅)₂-Ti(O-isoC₃H₇)₄-H₂O-C₂H₅OH-CH₃COOH and Ba(CH₃COO)₂-Ti(O-isoC₃H₇)₄-H₂O-CH₃COOH solutions. Relatively long gel fibres of 10cm length were obtained from both solutions in the limited composition region. The latter solution in particular showed a spinnability even when it contained no water. Therefore, the occurrence of spinnability of the solution was considered to be due to the formation of linear polymers composed of bridging acetate groups such as TiO-C(CH₃)-O-Ti rather than metalloxane bonding as Ti-O-Ti. Addition of water to the solutions seems to break the bridging acetate bonds and replace some of them by bridging oxygen bonds. The as-drawn gel fibres which were X-ray amorphous crystallized into BaTiO₃ ceramic fibres of 5mm average length upon heating above 600 ° C. However, the gel fibres drawn from the sols without water became powdery on heating because of the lack of Ti-O-Ti metalloxane bonds. The crystallization behaviour of the BaTiO₃ gel fibres is discussed based on the infrared spectroscopy, X-ray diffraction analysis and thermogravimetric-differential thermal analysis.     

Crystallization process and magnetic properties of Fe100−x,B x (10 ≦ × ≦ 35) amorphous alloys and supersaturated state of boron inα-Fe

Amorphous specimens of Fe_100–x B _x were prepared in the range 10 × 35 at % B by a single-roller method. The crystallization process and the boron concentration dependence of the Curie temperature were examined by differential scanning calorimetry, X-ray diffraction, Mössbauer spectroscopy and magnetic measurements. Two-step crystallization was observed in specimens with× < 17: amorphous amorphous + boron-supersaturated b c c phase (-Fe(B)) t-Fe₃B +-Fe. A single-Fe(B) phase was not observed. The transition temperature from t-Fe₃B to stable (-Fe + t-Fe₂B) sensitively depends on the boron content in the alloys. The crystallization temperature (T _x) of the amorphous alloys was almost unchanged for 17 × 31, but increased remarkably at high boron concentrations of× 33, where the decomposition products consisted of t-Fe₂B and o-FeB. The Curie temperature (T _c) of the amorphous phase was as low as 480 K at× = 10, increased with increasing boron content up to 820 K and then decreased in the high boron concentration alloys of× > 28. A single-Fe(B) phase was not detected in the as-quenched specimens of× = 8 and 10. The phase coexisted with the o-Fe₃B and amorphous phases. The lattice parameter of the phase was 0.2861₀ nm which was smaller than that of pure iron by 2/1000, indicating the substitutional occupation of boron atoms in the b c c lattice.     

Structural changes of glass-ceramics of the Cu2O-Al2O3-SiO2 system on heating in air

The behaviour of copper ions in low thermal expansion glass-ceramics prepared from Cu₂O · Al₂O₃ ·_nSiO₂ glasses, or in-spodumene type Cu₂O · Ae₂O₃ ·nSiO₂ crystals included in the glass-ceramics on heating in air was investigated. On hewing at 300 to 500° C, the copper ions behaved as in the corresponding glasses. Cuprous ions in the glass-ceramics or-spondumene type crystals were oxidized into the cupric state, and at the same time an equal amount of cuprous ions to those oxidized were expelled out of the specimen for the requirement of electrical charge neutrality and then reacted with oxygen to form CuO on the surface. The oxidation of cuprous ions and the decrease of the copper content of the-spondumene type crystals brought about a considerable decrease in the lattice spooings.     

Molecular Mechanisms and Tumor Biological Aspects of 5-Fluorouracil Resistance in HCT116 Human Colorectal Cancer Cells

5-Fluorouracil (5-FU) is a cornerstone drug used in the treatment of colorectal cancer (CRC). However, the development of resistance to 5-FU and its analogs remain an unsolved problem in CRC treatment. In this study, we investigated the molecular mechanisms and tumor biological aspects of 5-FU resistance in CRC HCT116 cells. We established an acquired 5-FU-resistant cell line, HCT116R^F10. HCT116R^F10 cells were cross-resistant to the 5-FU analog, fluorodeoxyuridine. In contrast, HCT116R^F10 cells were collaterally sensitive to SN-38 and CDDP compared with the parental HCT16 cells. Whole-exome sequencing revealed that a cluster of genes associated with the 5-FU metabolic pathway were not significantly mutated in HCT116 or HCT116R^F10 cells. Interestingly, HCT116R^F10 cells were regulated by the function of thymidylate synthase (TS), a 5-FU active metabolite 5-fluorodeoxyuridine monophosphate (FdUMP) inhibiting enzyme. Half of the TS was in an active form, whereas the other half was in an inactive form. This finding indicates that 5-FU-resistant cells exhibited increased TS expression, and the TS enzyme is used to trap FdUMP, resulting in resistance to 5-FU and its analogs.