纳米HS型沸石合成及长大机制的研究

通过清夜合成法成功地合成了纳米ＨＳ沸石,通过Ｘ射线粉末衍射法和高分辨率透 射电镜对产物进行了表征,并对其长大机制进行了分析．结果表明,纳米颗粒包含若干个尺寸 大致相同而晶体学位向不同的亚晶,其长大机制为聚集增长机制．     

Preparation and atomic force microscopy observation of lipid membranes on micro-patterned self-assembled monolayers

Using micro-contact printing (μCP) method, lipid membranes were deposited on the surface of micro-patterned self-assembled monolayers. Height and phase mode atomic force microscopy (AFM) images showed that the resulting deposited films were flat and that a micro-patterned composite bilayer system was constructed. It was also shown that the use of crystalline phase lipid membrane is effective for the preparation of the micro-patterned composite bilayer system of membranes with flat surface.     

Carrier injection and transport in organic field-effect transistor investigated by impedance spectroscopy

In this research, impedance spectroscopy (IS) has been applied on top-contact pentacene organic field-effect transistors (OFETs) for characterization of the contact resistance and carrier transport properties. The various relaxation processes were analyzed based on the Maxwell–Wagner model, assuming pentacene as a dielectric material. The mobilities obtained from the IS analysis correspond well with that obtained from the current–voltage (I–V) analysis. This alternative method by IS provides an additional advantage of isolating the effect of carrier concentration when evaluating the mobility of OFETs.     

The influence of reaction layer on the strength of aluminum/steel joint welded by resistance spot welding

We investigated the influence of interfacial reaction layer on the strength of resistance spot welded aluminum/steel joint by analyzing fracture surface and observing interfacial structure. The results revealed that the interfacial strength was approximately 6.509 MPa in the case that the reaction layer thickness exceeds 1.5 µm.     

Improved route for the synthesis of colloidal NaYF4 nanocrystals and electron spin resonance of Gd3+ local probe

This paper presents the synthesis and characterization of colloidal NaYF4 and NaYF4:20% Gd lanthanide nanocrystals. The nanoparticles were prepared by chemical route using co-thermolysis of Na(CF3COO), Y(CF3COO)3 and Gd(CF3COO)3 precursor in oleylamine surfactant/phenylether at Ts = 250 degrees C. By tuning the precursor/surfactant molar ratio during the process, it was possible to control the crystalline phase, chemical order and size of the nanocrystals. The nanocrystals were characterized by Transmission Electron Microscopy, Small Angle X-ray Scattering, powder X-ray Diffraction, dc-magnetization and Electron Spin Resonance (ESR) techniques. The ESR experiments show the so called U-spectrum for the Gd3+ ions in bulk counterpart materials, where characteristic powder spectra of cubic and lower crystal field symmetries were observed.     

Correction of the thermal neutron capture cross section of 241Am obtained by the Westcott convention

There is large discrepancy among the reported experimental data of the thermal neutron capture cross section of ²⁴¹Am, where the activation measurements provided larger cross sections than those in the time-of-flight ones. The Westcott convention has been widely used for the derivation of the thermal neutron capture cross section in the activation measurements. We have estimated that this large discrepancy is due to the existence of the resonances below the cadmium cut-off energy (E_Cd ～ 0.5 eV). By reviewing the Westcott convention, we developed the correction method taking account of the contribution of the resonances near or below E_Cd. The correction term was evaluated using the JENDL-4.0. Application of the present method successfully improved the existing discrepancy of the thermal capture cross section of ²⁴¹Am.     

On-line subcriticality measurement using a pulsed spallation neutron source

To investigate the applicability of the pulsed neutron source method using a pulsed spallation neutron source for an on-line subcriticality monitoring system of an accelerator-driven system, a subcritical experiment is conducted using the Kyoto University Critical Assembly in combination with the fixed-field alternating gradient accelerator. Reactivity values obtained from different traditional techniques, the area-ratio method and the α-fitting method, are discussed with respect to the applicability to on-line subcriticality monitoring. The results show that the area-ratio method robustly and accurately monitors subcriticality in shallow subcritical states with negative reactivity of up to a few dollars; however, this method faces problems with temporal fluctuations, spatial dispersion, and sensitivity to the proton-beam current with increasing depth of subcriticality. On the other hand, it is shown that the α-fitting method alleviates such problems in deep subcritical states. Moreover, a proposed fitting technique using the maximum-likelihood estimation method based on the Poisson distribution is robust enough to be applicable to on-line subcriticality monitoring for negative reactivity levels of up to roughly nine dollars.     

Spore rec-assay by dry sheet medium culture plate for bacterial counts

A simple and rapid method for spore rec-assay by utilizing dry sheet medium culture (Compactdry TC, CTC) for determining numbers of bacteria, instead of the spore agar plate, was developed. One mL of spore suspension (2 x 10(6)/mL) of Bacillus subtilis strain M45 Rec- or H17 Rec+ was inoculated in the center of the CTC plate. In the case of metabolic activation, 1 mL of mixed solution (spore suspension of M45 or H17: 9,000 x g supernatant of rat-liver homogenate treated with Aroclor 1254 = 19:1) was used. The spore suspension spreads over the whole sheet in seconds and gels. A paper disk impregnated with 20-40 microL of the sample solution and 20 microL of the cofactor solution was placed on the surface of CTC plate. For the assay of samples that do not require metabolic activation, use of the cofactor solution can be omitted. After 48 hr incubation at 37 degrees C, 0.01% MTT [3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide] aqueous solution (0.5 mL) was dropped uniformly on the plate. The plate was left for 5 min, and the diameter of the inhibition circle was measured with slide calipers. The samples for which the difference in inhibition zone between M45 and H17 was more than 2 mm were judged positive. Under these conditions, the DNA damaging activities of sodium sulfite, sodium benzoate and citric acid, used as food additives, were investigated by the proposed method. Sodium sulfite and sodium benzoate gave positive results and citric acid gave a negative result with or without metabolic activation, in agreement with the results obtained by the conventional method.     

Lupus anticoagulants in patients with systemic lupus erythematosus

Lupus anticoagulants (LA) and anticardiolipin antibodies (aCL) are known as thrombosis-related antiphospholipid antibodies. LA is not as well characterized as aCL, and the relation between LA and aCL is not clarified. Since standardized method for the detection of LA has not been established, we measured LA activities in outpatients with SLE by using two different methods (KCT and dRVVT), and analyzed the characteristics of LA in SLE. LA was detected in 29.8% of all samples (14.3% in both methods, 15.5% in one method). IgG-aCL and IgM-aCL was detected in 38% and 20%, respectively, of all LA positive samples. Though a good correlation was observed between LA activities and IgG-aCL levels, a considerable number of LA positive samples were negative for aCL. This indicated the presence of factors with LA activity other than aCL. On the contrary there was also a high percentage of LA negative samples with positive aCL (42.4% in IgG-aCL, 47.4% in IgM-aCL), suggesting the presence of aCL with poor or low LA activity. These findings showed the heterogeneity of antiphospholipid antibodies both in LA and in aCL. The platelet function tests showed increased platelet adhesiveness and normal platelet aggregation in LA positive patients with SLE even in the inactive phase. The serum levels of factors such as protein C, protein S, antithrombin III and thrombomodulin were within normal range. Clinical features such as hemolytic anemia, thrombosis and abortion were more frequently observed in LA positive population than in LA negative population. The clinical features tend to be different between patients with dRVVT-LA and those with KCT-LA, though not significant. Because of the heterogeneity in LA, a combination of more than two different methods including dRVVT was recommended for the detection and the evaluation of LA.     

Effects of light,CO2 and inhibitors on the current output of biofuel cells containing the photosynthetic organism Synechococcus sp

The current output of the biofuel cells containing a marine alga, Synechococcus sp. and an electron transport mediator, 2-hydroxy-1, 4-naph-thoquinone (HNQ) was increased under illumination and in the presence of CO₂. The inhibitory effects of carbonyl cyanide m-chlorophenylhydrazone (CCCP), 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU), 2,5-dibromomethylisopropyl-p-benzoquinone (DBMIB), phenylmercury acetate (PMA) and N,N′-dicyclohexyl-carbodiimide (DCCD) on the output current of fuel cells run in the light suggested that HNQ accepts electrons mainly at the site of ferredoxin-NADP⁺ reductase (FNR) in the electron transfer chain. The inhibition of light-induced generation of current output by CCCP indicates that the current is derived from photosynthetic oxidation of water. Endogenous glycogen in algae is required to sustain a steady current output from the fuel cells.