On-demand patterning of protein matrixes inside a microfluidic device

On-demand immobilization of proteins at specific locations in a microfluidic device would advance many types of bioassays. We describe a strategy to create a patterned surface within a microfluidic channel by electrochemical means, which enables site-specific immobilization of protein matrixes and cells under physiological conditions, even after the device is fully assembled. By locally generating hypobromous acid at a microelectrode in the microchannel, the heparin-coated channel surface rapidly switches from antibiofouling to protein-adhering. Since this transformation allows compartmentalizing of multiple types of antibodies into distinct regions throughout the single microchannel, simultaneous assay of two kinds of complementary proteins was possible. This patterning procedure can be applied to conventional microfluidic devices since it requires only some electrodes and a voltage source (1.7 V, DC).     

Changes in Surface Property and Catalysis of Mesoporous Nb<Subscript>2</Subscript>O<Subscript>5</Subscript> from Amorphous to Crystalline Pore Walls

Abstract  

The amorphous inorganic phase of an ordered amorphous mesoporous Nb₂O₅ with two dimensional hexagonal (2D-hex) structure was crystallized with maintaining the original well arranged porous structure. The difference in surface property between amorphous and crystalline Nb₂O₅ with similar ordered mesoporous structure was compared. It was found from water adsorption–desorption isotherms and observation by infrared (IR) spectroscopy that the amorphous sample was hydrophilic and that the surface OH groups were acidic. On the other hand, the OH groups on crystalline mesoporous Nb₂O₅ were non-acidic and inside the pores was less hydrophilic. The surface property was also compared by a catalytic reaction, oxidation of cyclohexe by an aqueous solution of H₂O₂. The high (95%) selectivity for 1,2-epoxycyclohexane was obtained at 40 °C for 2 h in methanol solvent over crystalline mesoporous Nb₂O₅ at 12% conversion, while amorphous mesoporous Nb₂O₅ showed high (68%) selectivity for 1,2-cyclohexanediol in acetonitrile solvent at 60 °C for 2 h at 22% conversion. The differences in selectivity and the optimal solvent between amorphous and crystalline samples were interpreted in terms of the acidic feature of surface OH groups and hydrophilicity. While similar selectivity was observed over non-porous crystalline Nb₂O₅, much higher conversion over crystalline mesoporous Nb₂O₅ was attained at the same surface area. Thus, an advantage of mesoporous structure is attributed to the higher contact time of molecules inside the pores to the catalyst surface than those outside the particles.     

Low-Temperature Fabrication of Transparent Yttrium Aluminum Garnet (YAG) Ceramics without Additives

A carbonate precursor of yttrium aluminum garnet (YAG) with an approximate composition of NH₄AlY_0.6(CO₃)_1.9(OH)₂·0.9H₂O was synthesized via a coprecipitation method from a mixed solution of ammonium aluminum sulfate and yttrium nitrate, using ammonium hydrogen carbonate as the precipitant. The precursor precipitate was characterized using chemical analysis, differential thermal analysis/thermogravimetry, X-ray diffractometry, and scanning electron microscopy. The sinterability of the YAG powders was evaluated by sintering at a constant rate of heating in air and vacuum sintering. The results showed that the precursor completely transforms to YAG at ∼1000°C via the formation of a yttrium aluminate perovskite (YAP) phase. YAG powders obtained by calcining the precursor at temperatures of ≤1200°C were highly sinterable and could be densified to transparency under vacuum at 1700°C in 1 h without additives.     

Measurements of thermal-neutron capture cross-section and resonance integral of neptunium-237

The thermal-neutron capture cross-section (σ₀) and resonance integral (I₀) were measured for the ²³⁷Np(n,γ) ²³⁸Np reaction by an activation method. A method with a Gadolinium filter, which is similar to the Cadmium difference method, was used to measure the σ₀ with paying attention to the first resonance at 0.489 eV of ²³⁷Np, and a value of 0.133 eV was taken as a cut-off energy. Neptunium-237 samples were irradiated at the pneumatic tube of the Kyoto University Research Reactor in Institute for Integral Radiation and Nuclear Science, Kyoto University. Wires of Co/Al and Au/Al alloys were used as monitors to determine thermal-neutron fluxes and epi-thermal Westcott’s indices at an irradiation position. A γ-ray spectroscopy was used to measure activities of ²³⁷Np, ²³⁸Np and neutron monitors. On the basis of Westcott’s convention, the σ₀ and I₀ values were derived as 186.9 ± 6.2 barn, and 1009 ± 90 barn, respectively.     

High-Performance Liquid Chromatography with Fluorescence Detection for Simultaneous Analysis of Phytosterols (Stigmasterol, β-Sitosterol,Campesterol, Ergosterol,and Fucosterol) and Cholesterol in Plant Foods

A method based on high-performance liquid chromatography (HPLC) with fluorescence (FL) detection for the simultaneous analysis of phytosterols (stigmasterol, β-sitosterol, campesterol, ergosterol, and fucosterol) and cholesterol was developed. To fluoresceinate the sterols, they were derivatized by 1-anthroyl cyanide to the hydroxyl group at carbon 3 of each sterol skeleton. This HPLC-FL method consists of a C-30 column, an isocratic solution using acetone/acetonitril/hexane/water (71:20:4:5, v/v) as the mobile phase at 1.0 mL min^?1 and fluorescence detection at an excitation of 370 nm and an emission of 470 nm. The separation of five phytosterols, cholesterol, and 1-hexacosanol as an internal standard was achieved with sufficient reproducibility and quantitative ability. Our method could evaluate the sterols of land plants such as wood ear fungus, soybean, and parsley, as well as marine algae such as Hiziki (Phaeophyta), Ogonori (Rhodophyta), and Heraiwazuta (Chlorophyta). As a result of the analysis of land plants, wood ear contained a large amount of ergosterol as a precursor of vitamin D₂. Soybean contained a large amount of stigmasterol, campesterol, and β-sitosterol. Parsley contained small amounts of these sterols compared with wood ear and soybean. Among the marine algae, Hiziki, Ogonori, and Heraiwazuta contained large amounts of fucosterol, cholesterol, and β-sitosterol, respectively. The compositions of marine algae differed from those of land plants.     

Evaluating river water quality through land use analysis and N budget approaches in livestock farming areas

This study was carried out to evaluate the quality of river water by analysis of land use in drainage basins and by estimating the N budgets. The drainage basins of Shibetsu River (Shibetsu area) and Bekkanbeushi River (Akkeshi area) in eastern Hokkaido, Japan were selected for a case study, and the evaluation of water quality was up-scaled to the regional level in Hokkaido by using the Arcview/GIS and statistical information. Water sampling was carried out in August 2001 and May 2002 in the Shibetsu and Akkeshi areas, respectively. The proportions of major land uses in drainage basins such as upland field, forest, urban area, wetland and wasteland for each sampling site were estimated by using topographic maps scaled at 1:25,000. The linear regression results showed that the correlation between NO3-N concentration and the proportion of upland in the drainage basins was highly and positively significant for both the Shibetsu area (r = 0.84, n = 57) and the Akkeshi area (r = 0.71, n = 73) at < 0.001 significance level. The regression coefficients or impact factors of river water quality were 0.015 and 0.0052 for the Shibetsu and Akkeshi areas, respectively. A comparison of these results with that of the previous study results in Hokkaido indicated that the impact factors were highest for intensive livestock farming areas (0.040), medium for mixed agriculture and livestock farming (0.020-0.030), and the lowest for grassland-based dairy cattle and horse farming areas (0.0052-0.015). The results of a simple regression analysis showed that the impact factors had a significant positive correlation with the cropland surplus N (r = 0.93, P < 0.01), chemical fertilizer N (r = 0.82, P < 0.05), and manure fertilizer N (r = 0.76, P < 0.05), which were estimated by using the N budget approach. Using the best-correlated regression model, impact factors for all cities, towns and villages of the Hokkaido region were estimated. The NO3-N concentrations for all major rivers in Hokkaido were predicted by multiplying the estimated impact factors by the proportion of uplands. The regression analysis indicated that the predicted NO3-N concentrations were significantly correlated (r = 0.62, P < 0.001, n = 203) with the measured NO3-N concentrations, reported previously. It can be concluded that estimating the proportions of upland fields in drainage basins, and calculating cropland surplus N enables us to predict river water quality with respect to NO3-N concentration.     

Hydrogen production by steam reforming of acetic acid: Comparison of conventional supported metal catalysts and metal-incorporated mesoporous smectite-like catalysts

The activities of various metal catalysts were tested in steam reforming of acetic acid for the production of H₂, using conventional metal oxides and transition metal-incorporated mesoporous smectite-like materials as supports. It has been found that Pt is superior to Ni, Co, and Fe among Al₂O₃ supported catalysts, Al₂O₃ is more effective than ZrO₂ and SiO₂ as support for Pt, Ni incorporated smectite (SM(Ni)) support is more effective than Fe and Co incorporated ones for Pt, and SM(Ni) is also active in the absence of Pt. The total activity for the conversion of acetic acid is in the order of Pt/Al₂O₃ > Pt/SM(Ni) > SM(Ni) but the ability of H₂ production is comparable among these catalysts. These catalysts (and the other ones) were observed to lose their activities during the reforming reactions. The activity of Pt/Al₂O₃ decreased during the whole course of reaction up to 10 h. In contrast, the activity of SM(Ni) also decreased within 2 h but it showed a stable activity in the following stage of reaction. The initial activity of the used Pt/SM(Ni) and SM(Ni) was able to be almost completely restored by thermal treatment with H₂ but less effectively for the used Pt/Al₂O₃. The catalyst deactivation was shown to occur by the formation and deposition of carbon materials on the catalysts (XRD, TEM, thermal analysis). The properties of carbon deposits formed on Pt/Al₂O₃ and SM(Ni) catalysts should be different and this may be responsible for the differences in the extent of deactivation and in the regeneration behavior between the two catalysts.     

Mixed-model assembly line scheduling using the Lagrangian relaxation technique

The increasing market demand for product variety forces manufacturers to design mixed-model assembly lines on which different product models can be switched back and forth and mixed together with little changeover costs. This paper describes the design and implementation of an optimization-based scheduling algorithm for mixed-model compressor assembly lines at Toshiba with complicated component supply requirements. A separable integer optimization formulation is obtained by treating compressor lots going through a properly balanced line as undergoing a single operation, and the scheduling goal is to delivery products just in time while avoiding possible component shortage. The problem is solved b y using Lagrangian Relaxation (LR). Several generic defects of LR leading to slow algorithm convergence are identified based on geometrical insights, and are overcome by perturbing/ changing problem parameters. Numerical testing shows that near-optimal schedules are efficiently obtained, convergence is significantly improved, and the method is effective for practical problems. The system is currently under deployment at Toshiba     

Fast calculation method for fine‐tuned design of need‐based collateralized debt obligation (CDO)

In this paper we propose a speed‐up method for need‐based collateralized debt obligation (CDO) that meets the investor needs of the attributes of the CDO. We note the fact that the computing time to derive the best portfolio is proportional to the number of generated contract conditions that constitute the portfolio. Our method reduces the number of portfolios that can never be the best portfolios by skipping the generation of redundant contract conditions of Super Senior (SS) debt and Equity debt, which is the main cause for the increase of the generated contract conditions. A comparative experiment indicates that the proposed method makes it possible to double the types of tranches or to raise the calculation accuracy nearly 6‐fold, keeping the urgency of the calculation. Copyright © 2007 Institute of Electrical Engineers of Japan© 2007 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Design study of a multibeam type IH-RFQ linac to accelerate high intensity and low energy heavy ion beams

A multibeam Radio Frequency Quadrupole (RFQ) linac with an Interdigital H-mode (IH) structure has been developed for high intensity heavy-ion beam acceleration. The defocusing force of space charge effect is proportional to the beam current and to the inverse square of the beam velocity. Therefore, multibeam acceleration is an attractive scheme to suppress this in the low energy region. The electromagnetic field distribution and the beam dynamics were studied for a prototype. We discuss the configuration of the multibeam IH-RFQ linac and the results of these simulations.