2D spinodal phase-separated TiO2 films prepared by sol-gel process and photocatalytic activity

For the purpose of obtaining oxide thin films with high photocatalytic activity, we have successfully prepared the TiO₂ anatase polycrystalline films with a two-dimensional spinodal phase-separated structure (2D-SPSS) in micron size by the sol-gel dip-coating method from a titanium tetraisopropoxide solution containing polyoxyethylene(20) nonylphenyl ether. It has been also found that TiO₂ films with a variety of morphologies in addition to the 2D-SPSS can be formed by controlling the molar ratio of water to titanium tetraisopropoxide. The methylene blue photodegradation activity of the 2D-SPSS TiO₂ film was higher than that of dense TiO₂ film prepared from a TiO₂ sol without co-existing polymer. This fact can be interpreted in terms of possessing a high specific surface area available for the photocatalytic reaction.     

High‐mobility oxide TFT for circuit integration of AMOLEDs

Abstract— A high‐mobility and high‐reliability oxide thin‐film transistor (TFT) that uses In‐Sn‐Zn‐O (ITZO) as a channel material has been developed. The mobility was 30.9 cm²/V‐sec and the threshold voltage shift after 20,000 sec of a bias‐temperature‐stress (BTS) test (with a stress condition of Vg = 15 V, Vd = 15 V, and T = 50°C) was smaller than 0.1 V. In addition, a method of obtaining a stable enhancement‐type TFT, which realizes circuit integration for active‐matrix organic light‐emitting diode (AMOLED) displays has been developed.     

Effect of Nitrogen Profile and Fluorine Incorporation on Negative-Bias Temperature Instability of Ultrathin Plasma-Nitrided SiON MOSFETs

The effects of plasma nitridation and fluorine incorporation on the components of negative-bias temperature instability (NBTI) in p-type MOSFETs with plasma-nitrided SiON gates were investigated. To clarify these effects, NBTI-induced threshold-voltage shift was separated into two components: one for generation of traps at the SiON/Si-substrate interface and one for positive charges within the SiON bulk. It was found that the proportions of the interface and bulk components can be controlled with the plasma nitridation method: The bulk component was increased by radio-frequency plasma nitridation, while the interface component was dominant in the case of electron-cyclotron-resonance plasma nitridation. Lowering the nitrogen concentration near the SiON/Si-substrate interface decreased the interface component. Lowering the nitrogen concentration near the poly-Si/SiON interface did not decrease NBTI, while it decreased positive oxide charges in the as-fabricated MOSFETs. Furthermore, it was demonstrated that the fluorine incorporation decreases the interface component in plasma-nitrided SiON gates, while it does not decrease the bulk component.     

Impact of Crystalline Phase of Ni-FUSI Gate Electrode on Bias Temperature Instability and Gate Dielectric Breakdown of HfSiON MOSFETs

We investigated the influences of gate metals (n⁺/p⁺ poly-Si, Ni silicide (NiSi), Ni₃Si) on the time dependent dielectric breakdown (TDDB) reliability and negative/positive bias temperature instability (NBTI/PBTI) of phase-controlled Ni-full-silicide (Ni-FUSI)/HfSiON/SiO ₂ FETs. The TDDB reliability of NiSi-electrode n-FETs was comparable to that of n⁺-poly-Si-electrode n-FETs. However, further Ni enriching of the electrode to Ni₃Si degraded the reliability. A degradation of the base SiO₂ layer seems to have been responsible for this. A higher compressive strain was observed for the Ni₃Si sample, which may have caused the degradation of the bottom SiO₂. In contrast, the TDDB reliability of p-FETs improved much by using Ni₃Si. We attribute this improvement to the lower cathode energy and/or the absence of boron in the gate electrode. The PBTI of the n-FETs was negligible and was not degraded by Ni enrichment of the gate electrode and additional annealing, suggesting that HfSiON was stable against the Ni-FUSI process. The threshold voltage (V_T) shift in NBTI of p-FETs did not depend much on the gate materials. The major component of the V _T shift in NBTI, however, was changed by Ni enriching from the generation of interface traps to the trapping of holes by the HfSiON bulk     

城市空间人口密度模型研究综述

自Clark(1951)提出城市空间传统密度模型后,城市空间人口密度分布研究进入了一个繁盛阶段.McDonald(1989)对70年代至80年代后半期城市人口密度分布研究成果进行了整理.本论文在此基础上,着重对反映城市化(尤其是其中的郊区化)进程中日趋复杂的现代城市空间结构变化的人口密度模型进行归纳整理.作为综述论文虽与McDonald(1989)会有部分重复,但论文范围扩展到90年代以后的相关研究成果.     

Optimal unit sizing of fuel cell cogeneration systems in consideration of performance degradation

The influence of the life of a cell stack due to performance degradation on a system's economy is investigated in unit sizing of fuel cell cogeneration systems. An optimal unit sizing method proposed by the authors is extended to this case so that it enables the life and performance degradation of the cell stack to be considered. In the method, equipment capacities and maximum contract demands of utilities such as electricity and natural gas are determined so as to minimize the annual total cost leveled for a whole planning period based on the annualized costs method, in consideration of operational strategies which change with performance degradation of the cell stack. Numerical studies are carried out for normally and highly pressurized phosphoric acid fuel cell cogeneration systems installed in two urban areas. Through the studies, it is found that the life of the cell stack greatly influences system' economics and equipment capacities. © 1998 John Wiley & Sons, Ltd.     

Specific Gut Microbial Environment in Lard Diet-Induced Prostate Cancer Development and Progression

Lard diet (LD) is a risk factor for prostate cancer (PCa) development and progression. Two immunocompetent mouse models fed with isocaloric specific fat diets (LD) enriched in saturated and monounsaturated fatty acid (SMFA), showed significanftly enhanced PCa progression with weight gain compared with a fish oil diet (FOD). High gut microbial divergency resulted from difference in diets, and the abundance of several bacterial species, such as in the orders Clostridiales and Lactobacillales, was markedly altered in the feces of LD- or FOD-fed mice. The proportion of the order Lactobacillales in the gut was negatively involved in SMFA-induced body weight gain and PCa progression. We found the modulation of lipid metabolism and cholesterol biosynthesis pathways with three and seven commonly up- and downregulated genes in PCa tissues, and some of them correlated with the abundance of the order Lactobacillales in mouse gut. The expression of sphingosine 1-phosphate receptor 2, which is associated with the order Lactobacillales and cancer progression in mouse models, was inversely associated with aggressive phenotype and weight gain in patients with PCa using the NCBI Gene Expression Omnibus database. Therefore, SMFA may promote PCa progression with the abundance of specific gut microbial species and overexpression of lipogenic genes in PCa. Therapeutics with alteration of gut microbiota and candidate genes involved in diet-induced PCa progression may be attractive in PCa.     

Synthesis,characterization, and CO2 permeation properties of acetylene‐terminated polyimide membranes

A novel fluorine‐containing telechelic polyimide end‐capped with acetylene group which derived from 4,4‐(hexafluoroisopropylidene) diphthalic anhydride (6FDA), 3,4‐diaminodiphenyl ether (DADE), and 4‐(2‐phenylethynyl) phthalic anhydride (PEPA) was synthesized using polycondensation. The physical and CO₂ permeation properties of its crosslinked membranes prepared by the cyclotrimerization reaction of the acetylene groups at the polymer chain end using tantalum (V) chloride (TaCl₅) as a catalyst under thermal treatment was investigated in terms of CO₂‐induced membrane plasticization. The crosslinked membranes showed a gel content in organic solvent, which was good solvent of noncrosslinked membranes, and improved their thermal stability. Based on the measurement of the high‐pressure time dependence on CO₂ permeation, the crosslinked 6FDA–DADE–PEPA membranes exhibited more resistance to CO₂‐induced plasticization than noncrosslinked 6FDA–DADE and thermal treated 6FDA–DADE–PEPA. Furthermore, the increase in TaCl₅ content resulted in more resistance to plasticization. The cyclotrimerization reaction of the acetylene groups at the polymer chain ends using a transition metal catalyst under thermal treatment was found to be more effective than conventional thermal treatments for suppressing membrane plasticization without the membrane densification. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers     

Production of MAG of CLA by esterification with dehydration at ordinary temperature using <Emphasis Type="Italic">Penicillium camembertii</Emphasis> lipase

Production of MAG with CLA using Penicillium camembertii mono- and diacylglycerol lipase (referred to as lipase) was attempted for the purpose of expanding the application of CLA. The commercial product of CLA (referred to as FFA-CLA) is a FFA mixture containing almost equal amounts of 9cis,11trans (9c,11t)-CLA and 10t,12c-CLA. Esterification of FFA-CLA with glycerol without dehydration achieved 84% esterification but produced almost equal amounts of MAG and DAG. Esterification with dehydration not only achieved a high degree of esterification but also suppressed the formation of DAG. When a mixture of FFA-CLA/glycerol (1∶2, mol/mol), 1% water, and 200 units/g-mixture of P. camembertii lipase was agitated at 30°C for 72 h with dehydration at 5 mm Hg, the degree of esterification reached 95% and the contents of MAG and DAG were 90 and 6 wt%, respectively. This reaction system may be applied to the industrial production of MAG with unstable CLA.     

Structural effect of a series of block copolymers consisting of poly(N-isopropylacrylamide) and poly(N-hydroxyethylacrylamide) on thermoresponsive behavior

Well-defined diblock and triblock copolymers consisting of poly(N-isopropylacrylamide) (PNIPAM) and poly(N-hydroxyethylacrylamide) (PHEAA) were prepared using the atom transfer radical polymerization (ATRP) method. The number-average molecular weight and fraction of each segment were precisely controllable by adjusting the monomer/initiator ratio in feed. The lower critical solution temperature (LCST) of a series of block copolymers with different compositions was examined using a turbidimetry analysis. The copolymers with a relatively lower molar fraction of HEAA units in the polymer chain exhibited phase transition phenomenon, in which the LCST depended on the fraction in the copolymer. On the other hand, the LCST disappeared for the copolymers with higher HEAA unit molar fractions. The ¹H NMR measurement clarified that the disappearance of the LCST was attributed to the formation of the water-soluble micelle. Furthermore, the thermoresponsive property of the series of block copolymers was elucidated on the basis of the structural effect of the copolymer, which includes the order and length of the block segments.