Sol–gel and rf sputtered AZO thin films: analysis of oxidation kinetics in harsh environment

Al-doped ZnO (AZO) thin film, which possess the advantages of low cost, low sheet resistance and high transmittance, are one of the most promising candidates to replace indium tin oxide films as the transparent electrode. However, oxidation causes a substantial increase in the sheet resistance of AZO film after exposing in ambient and especially, damp heat environment. In this work, we compare structural, optical, electrical properties and environmental stability between films prepared by two different methods: sol–gel and rf sputtering. Experimental results indicate that the properties of film can be affected by different deposition method. From the X-ray diffraction analysis, all films have hexagonal wurtzite crystal structure with different preferable orientation in two different methods. Optical transmittance spectra of the AZO films exhibited transparency higher than about 80 % within the visible wavelength region and the optical band gap (E_g) of these films was increased in sputtered film, probably due to the increase of carrier concentration. The better environmental stability was found in AZO film prepared by sputtering method. Improved surface morphology and enhancement of crystal orientation (110) was considered for this improvement.     

Structural Distortion and Compositional Gradients Adjacent to Epitaxial LiMn2O4 Thin Film Interfaces

Thin film electrode materials are key components in the development of high rate, high capacity solid‐state Li‐ion batteries. Detailed knowledge of the epitaxial film/substrate(current‐collector) interface structures, which provides insights into epitaxial growth mechanisms and the effects of microstructure on electrochemical properties, is essential for efficient materials and device design. Here we report the epitaxial growth mechanism of a typical cathodic LiMn₂O₄ thin film by exploring the detailed structural and compositional variations in the vicinity of a film/substrate interface using state‐of‐the‐art scanning transmission electron microscopy. Direct observation of atom columns shows the epitaxial film forms an atomically flat and coherent heterointerface with the substrate, but that the crystal lattice is tetragonally distorted with a measurable compositional gradient from the interface to the crystal bulk. The growth mechanism is interpreted in terms of a combination of chemical and physicomechanical effects, namely a complex interplay between the internal Jahn‐Teller distortions induced by oxygen non‐stoichiometry and the lattice misfit strain.     

Molecular structure of La3+-induced methanol dehydrogenase-like protein in Methylobacterium radiotolerans

La(3+) and not Ca(2+) increases methanol dehydrogenase (MDH) activity in Methylobacterium radiotolerans NBRC15690. La(3+)- and Ca(2+)-MDH-like proteins were found to be homodimeric (α(2)) and heterotetrameric (α(2)β(2)), respectively. N-terminal amino acid sequences of these proteins revealed that La(3+)- and Ca(2+)-MDH-like proteins were encoded by xoxF and mxaFI, respectively.     

Simultaneous induction of calcium transients in embryoid bodies using microfabricated electrode substrates

Precise control of differentiation processes of pluripotent stem cells is a key component for the further development of regenerative medicine. For this purpose, combining a cell-aggregate-size treatment for regulating intercellular signal transmissions and an electrical stimulation technique for inducing cellular responses is a promising approach. In the present study, we developed microfabricated electrode substrates that allow simultaneous stimulation of embryoid bodies (EBs) of P19 cells. Mouse embryonal carcinoma P19 cells can be induced to differentiate into three germ layers and serve as a promising stem cell model. Microcavity–array patterns were fabricated onto indium–tin–oxide (ITO) substrates using a standard photo-lithography technique, and uniform-sized EBs of P19 cells were inserted into each microcavity. Electrical stimulation was applied to the EBs through substrate electrodes and stimulus-induced intracellular calcium transients were monitored. We confirmed that the developed electrode device could simultaneously stimulate smaller (200 μm diameter) and larger (500 μm diameter) EBs inserted in the microcavities and induce specific spatio-temporal patterns of intracellular calcium transients in the EBs with fine reproducibility. We concluded that the developed microcavity array with embedded electrodes could simultaneously and effectively stimulate uniform-sized EBs inserted in it. Therefore, it is a promising experimental tool for precisely controlling cell differentiation processes.     

The role of vitamin E in T-cell differentiation and the decrease of cellular immunity with aging

Spontaneously hypertensive rats (SHR) as a model for aging were used in this experiment and fed a regular (50 IU/Kg diet) or high vitamin E (500 IU/Kg diet) diet for 6 weeks. At 12 weeks old, they were killed and assayed. Although proliferation of thymic lymphocytes was significantly decreased in SHR fed the regular diet compared to Wistar Kyoto rats (WKY) fed the same diet, high vitamin E diet enhanced proliferation of thymic lymphocytes in SHR to almost the levels in WKY fed the regular diet. In addition, the expressions of both CD4 and CD8 antigens on CD+CD8+ T cells, immature T cells existing in thymic cortex, were also decreased in SHR, and significantly improved by high vitamin E diet. These results suggest that high vitamin E diet enhances thymic lymphocyte proliferation through increased T-cell differentiation in thymus. Then, the effect of vitamin E on T-cell differentiation in thymus was investigated by using male Fisher rats. Rats were divided into three groups; vitamin E-free, regular and high vitamin E groups and fed a diet containing various levels of vitamin E (0, 50 and 500 IU/Kg diet) for 7 weeks. Although the percentages of CD4+CD8- and CD4-CD8+ T cells in thymocytes were significantly greater in the high vitamin E group, the percentage of CD4+CD8- T cells inversely decreased in the vitamin E-free group compared to the regular group. We have tried to investigate the mechanism of the increased T-cell differentiation in thymus of rats fed the high vitamin E diet through cytokine production, and thymic epithelial cell (TEC) and macrophage functions. We have found that vitamin E enhances T-cell differentiation through the increase of not macrophage but TEC function in thymus, which is associated with the increased binding capacity of TEC to immature T cells via increased expression of adhesion molecule, ICAM-1. These results suggest that vitamin E is a potent nutrient for promoting health in the aged via the improvement of cellular immunity decreased with aging.     

Activation of the protein kinase p38 in the spindle assembly checkpoint and mitotic arrest

The mitogen-activated protein kinase (MAPK) superfamily comprises classical MAPK (also called ERK), c-Jun amino-terminal or stress-activated protein kinase (JNK or SAPK), and p38. Although MAPK is essential for meiotic processes in Xenopus oocytes and the spindle assembly checkpoint in Xenopus egg extracts, the role of members of the MAPK superfamily in M phase or the spindle assembly checkpoint during somatic cell cycles has not been elucidated. The kinase p38, but not MAPK or JNK, was activated in mammalian cultured cells when the cells were arrested in M phase by disruption of the spindle with nocodazole. Addition of activated recombinant p38 to Xenopus cell-free extracts caused arrest of the extracts in M phase, and injection of activated p38 into cleaving embryos induced mitotic arrest. Treatment of NIH 3T3 cells with a specific inhibitor of p38 suppressed activation of the checkpoint by nocodazole. Thus, p38 functions as a component of the spindle assembly checkpoint in somatic cell cycles.     

Model predictive control with adaptive disturbance prediction and its application to fatty acid distillation column control

This paper describes the results of a joint university-industry study to control a fatty acid distillation sequence, which is plagued with severe disturbance problems. In order to solve the disturbance problem, a model predictive control algorithm is modified in terms of disturbance prediction. Assuming that the dynamics of the unmeasured disturbances is generated by an auto-regressive form, the dynamics of the disturbance can be adaptively identified by using time series data of prediction errors and inputs. Using an identified disturbance model with a process model, future outputs are predicted. Control actions are determined so that the predicted output is as close to the target value as possible. This modified model predictive control aglorithm is applied to a ratio control scheme for three distillation columns. The control system developed has been in use sucessfully for more than six years to produce commercial products.     

Adsorption and photocatalytic decomposition of methylene blue on mesoporous metallosilicates

Mesoporous silica and mesoporous metallosilicates with Al, Ti and Fe as foreign metal species were successfully synthesized by the rapid room temperature method. Mesoporous metallosilicates with low contents of foreign metals possessed high surface area (S_a), large mesopore volume (V_mp) and highly ordered hexagonal mesoporous structure. Increases in foreign metal contents caused disordering the mesoporous structures and lowering the S_a and V_mp values. Bleaching of aqueous methylene blue (MB) by mesoporous silica and metallosilicates was investigated. Mesoporous aluminosilicate and ferrosilicate with cation-exchangeable ability showed the excellent property for the adsorption of MB of cationic dye, while mesoporous ferrosilicate and titanosilicate which absorbed UV lights catalyzed the photocatalytic decomposition of MB under UV-illumination.     

Microstructures and Vickers hardness of rapidly solidified Al-Cu alloys near the Al-Al2Cu equilibrium eutectic composition

Al-Cu alloys near the Al-Al₂Cu equilibrium eutectic composition were rapidly solidified by the single-roller method. Two-zone structures were observed in transverse sections of Al-24.8, 30.0, 32.7, 33.2, 37.0 and 40.3 mass % Cu alloy ribbons, which were interpreted on the basis of the difference in cooling rates and of the temperature gradients between the chilled and free-surface sides of the ribbons. Non-equilibrium eutectic structures, cellular and irregular lamellar, were seen at the chilled side because the alloy liquids were directionally solidified with coupled eutectic growth. The coupled zone of the Al-Cu alloy expanded over the composition range 24.8–40.3 mass % Cu by rapid solidification. Dendritic structures were formed at the unchilled side of Al-24.8, 30.0, 37.0 and 40.3 mass % Cu alloys. Vickers hardness values at the chilled side differed from those at the unchilled side due to the difference in the microstructure.     

Catalytic performance of K-promoted Rh/USY catalysts in preferential oxidation of CO in rich hydrogen

K-promoted Rh/USY (molar ratio: K/Rh=3) catalyst was found to exhibit high performance in preferential oxidation of CO in rich hydrogen. Such high performance was maintained in the presence of steam and CO₂. The CO oxidation activity of the K-Rh/USY catalyst was independent of the partial pressure of H₂, while the activity of the unpromoted Rh/USY catalyst was decreased significantly in hydrogen-rich stream. The effect of potassium addition on the catalyst structure was investigated and is discussed in terms of the differences in the catalytic performance.