X射线—极紫外光学中的超精密加工及其应用

短波光学技术的发展对高精密超光滑表面提出了严格要求。在X射线—极紫外光学中,光学元件表面粗糙度均方根值必须达到埃量级。制造这样表面的超精加工包括切割、研磨和抛光等工艺过程。本文介绍一种制造X射线望远镜中非球面镜的复制方法。     

Adsorption of phenol and reactive dye from aqueous solution on activated carbons derived from solid wastes

Activated carbons were produced from several solid wastes, namely, waste PET, waste tires, refuse derived fuel and wastes generated during lactic acid fermentation from garbage. Activated carbons having various pore size distributions were obtained by the conventional steam-activation method and via the pre-treatment method (i.e., mixture of raw materials with a metal salt, carbonization and acid treatment prior to steam-activation) that was proposed by the authors. The liquid-phase adsorption characteristics of organic compounds from aqueous solution on the activated carbons were determined to confirm the applicability of these carbons, where phenol and a reactive dye, Black5, were employed as representative adsorbates. The hydrophobic surface of the carbons prepared was also confirmed by water vapor adsorption. The characteristics of a typical commercial activated carbon were also measured and compared. It was found that the activated carbons with plentiful mesopores prepared from PET and waste tires had quite high adsorption capacity for large molecules. Therefore they are useful for wastewater treatment, especially, for removal of bulky adsorbates.     

Preparation and characterization of Ni-based positive electrodes for use in aqueous electrochemical capacitors

We have prepared NiO particles on Ni sheet and Ni foam substrates by chemical bath deposition and the following heat-treatment, and assembled a hybrid capacitor (HC) cell with the NiO-loaded Ni sheet or Ni foam positive electrode and activated carbon negative electrode. The deposited NiO particles had flower-like porous morphology which was composed of aggregated nanosheets. The maximum operating voltage of both HC cells was 1.5 V, which was much higher than theoretical decomposition voltage of water (1.23 V). The HC cell with NiO/Ni foam (HC_foam) had higher discharge capacitance and high-rate dischargeability and lower IR drop than the HC cell with NiO/Ni sheet (HC_sheet) because of the increase in the utilization of NiO active material. Both energy and power densities per mass of active materials, were much higher than those for the HC_sheet. Both HC_foam and HC_sheet showed excellent cycle stability for 2000 cycles.     

Phase and Formation/Dissolution of Precipitates in Biomedical Co-Cr-Mo Alloys with Nitrogen Addition

The precipitates in as-cast and heat-treated biomedical Co-28Cr-6Mo-(0 to 0.35)C-(0.15 to 0.25)N alloys (mass pct) were investigated. Heat treatment was carried out at temperatures of 1473?K to 1573?K (1200???C to 1300???C) for holding periods of 0 to 43.2?ks. In the as-cast and heat-treated Co-Cr-Mo-N alloys, no precipitates were detected; nitrogen effectively inhibited the formation of the ??-phase and stabilized the face-centered cubic (fcc) metallic ??-phase. The precipitates observed in the as-cast and heat-treated Co-Cr-Mo-C-N alloys were of the M₂₃X₆ type, M₂X type, ??-phase (M₂T₃X type with a ??-Mn structure), and ??-phase (M₆X-M₁₂X type). Complete precipitate dissolution was detected in the alloys with carbon contents of less than 0.3 mass pct regardless of the nitrogen content. The main precipitates were of the M₂X and M₂₃X₆ types after heat treatment for 1.8 to 43.2?ks. The ??-phase precipitate was detected in the early stage of heat treatment at high temperatures. The formation of the M₂X-type precipitate was enhanced by the addition of nitrogen, although the constitution of the precipitates depended on the balance between the nitrogen and carbon contents and the heat-treatment conditions.     

Expression and purification of recombinant human annexin A2 in Pichia pastoris and utility of expression product for detecting annexin A2 antibody

Annexin A2, a Ca2+-dependent phospholipid binding protein, is abundantly expressed in various human organs, which exists as either a membrane-associated, cytosolic or soluble form in serum. We constructed expression systems for recombinant human annexin A2 (rhA2) using Pichia pastoris. The systems are designed to secrete rhA2 as either the N- or C-terminally His6-tagged form to facilitate purification. Both types of rhA2 were overexpressed, but in the N-terminal-truncated form as revealed from the results of N-terminal amino acid sequencing and Western blotting. Therefore, further purification of N-terminally His6-tagged rhA2 was not feasible because of the removal of the N-terminal His6-tag sequence. C-terminally His6-tagged rhA2 was expressed as either a glycosylated or a nonglycosylated form, and the nonglycosylated form was purified using the combination of nickel-immobilized affinity, concanavalin A and cation exchanged column chromatographies. The solid-phase binding of rhA2 was examined by enzyme-linked immunosorbent assay (ELISA), which revealed the specific reactivity of rhA2 against an anti-annexin A2 monoclonal antibody. These results suggest that the expression system using P. pastoris is useful for the preparation of rhA2 that is applicable to the ELISA detection of the anti-annexin A2 antibody.     

Simplified method for preparing methylene-blue-sensitized dichromated gelatin

Methylene-blue-sensitized dichromated gelatin (MBDCG) is a suitable material for recording full-color holograms in a single layer. However, a drying process in an ammonia atmosphere is necessary to prepare the MBDCG plate. This process is time-consuming and unstable. A simplified method for preparing the MBDCG plate is presented in which the MBDCG can be dried without ammonia. Elimination of the drying process is possible when the methylene blue in MBDCG does not separate. This is achieved by a decrease in the concentration of dichromate in the photosensitized solution and the addition of an ammonia solution to the photosensitized solution. Last, the gelatin is allowed to gel. A Lippmann color hologram grating with a diffraction efficiency of more than 80% is obtained by use of this MBDCG.     

Effect of surface roughness and subsurface damage on grazing-incidence x-ray scattering and specular reflectance

Grazing-incidence specular reflectance and near-specular scattering were measured at Al-K(alpha) (1.486-keV, 8.34-?) radiation on uncoated dielectric substrates whose surface topography had been measured with a scanning probe microscope and a mechanical profiler. Grazing-incidence specular reflectance was also measured on selected substrates at the Cu-K(alpha) (8.047-keV, 1.54-?) wavelength. Substrates included superpolished and conventionally polished fused silica; SiO(2) wafers; superpolished and precision-ground Zerodur; conventionally polished, float-polished, and precision-ground BK-7 glass; and superpolished and precision-ground silicon carbide. Roughnesses derived from x-ray specular reflectance and scattering measurements were in good agreement with topographic roughness values measured with a scanning probe microscope (atomic force microscope) and a mechanical profiler that included similar ranges of surface spatial wavelengths. The specular reflectance was also found to be sensitive to the density of polished surface layers and subsurface damage down to the penetration depth of the x rays. Density gradients and subsurface damage were found in the superpolished fused-silica and precision-ground Zerodur samples. These results suggest that one can nondestructively evaluate subsurface damage in transparent materials using grazing-incidence x-ray specular reflectance in the 1.5-8-keV range.     

Country domain governance: an analysis by data-mining of country domains

Along with protocols, domain names are critical internet resources. To build a safe, secure, and globally ubiquitous internet, all entities responsible for the governance of domains must allocate their lower-level domains with competence and discipline following the basic principle of decentralized governance. The governance and operation of a country code top-level domain is delegated to the governing and operating entity of the relevant country or territory. There are great differences among these entities in domain allocation policy, fees, discipline, and technical competence. The undertaking of governing a global infrastructure requiring high integrity, such as the internet, on the basic principle of decentralized governance is unprecedented. To enable this governance to work well, it is necessary to set up proper objectives for the governance of country domains, and to use highly transparent criteria for a multi-faceted evaluation of how far these objectives have been achieved. This article presents a set of country domain governance indicators which is intended to be used for the construction of a safe and secure ubiquitous global network.     

A design scheme of discrete robust PID control systems and its application

PID controllers have been widely used in many chemical processes. Because they have only three control parameters, we can easily understand their physical meanings. However, it is difficult to tune their parameters in the case where the control system has uncertainties, for example, modeling errors, system fluctuation, and so on. Therefore, we propose a design scheme of discrete robust PID controllers in this paper. That is, we design a PID controller in connection with the generalized minimum variance control (GMVC) scheme, and present a scheme on how to design a weighting factor included in the GMVC criterion from the viewpoint of robust stability. Furthermore, we investigate the behavior of the proposed control scheme by applying it to an air pressure control system. © 1999 Scripta Technica, Electr Eng Jpn, 128(4): 77–83, 1999     

Role of the outermost subdomain of Salmonella flagellin in the filament structure revealed by electron cryomicroscopy

A mutant strain of Salmonella typhimurium, SJW46, has flagellar filaments supercoiled in the same form as the wild-type strain, SJW1103, and swims normally. However, its flagellar filaments are mechanically unstable and show anomalous behaviors of polymorphism. Flagellin from SJW46 has a large central deletion from Ala204 to Lys292 of SJW1103 flagellin, which has been thought to be located in the outer surface of the filament. Since the filament structure is determined by intersubunit interactions of the terminal regions in the densely packed core of the filament, no serious involvement of the deleted portion was expected in the filament stability and polymorphism. In order to locate the deleted portion and to understand the underlying mechanism of these anomalous characteristics, we carried out structure analysis of the L-type straight filament reconstituted from a mutant flagellin of SJW46 (SJW46S) and compared the structure with that of the SJW1660 filament, which is also the L-type but composed of flagellin with no deletion. The deleted portion was identified as the outermost subdomain, and the structure in the core region showed no appreciable differences. The structure revealed the previously identified folding of flagellin in further detail, and the significance of intersubunit interactions between outer domains, which are present in the SJW1660 filament but absent in the SJW46 filament. This suggests that these contacts have a significant contribution to the filament stability and polymorphic behavior, despite the fact that the contacting surface area occupies only a minor portion of the whole intersubunit interactions.