Development of the radiation-hardened Magnetically Suspended Compound Molecular Pump

The Magnetically Suspended Compound Molecule Pump is used for the vacuum pumping system in the 3 GeV Rapid Cycle Synchrotron (3 GeV-RCS) at Japan Proton Accelerator Research Complex (J-PARC). Due to the radiation environment it is used under, the pump must be resistant to at least 10 MGy of radiation. The standard Magnetically Suspended Compound Molecular Pump is only capable of withstanding up to 3.5 MGy under the radiation environment. For this reason, the radiation-hardened Magnetically Suspended Compound Molecular Pump was developed based on the gamma-ray irradiation examination results for the standard Magnetically Suspended Compound Molecular Pump, and an irradiation test was performed. The radiation-hardened Magnetically Suspended Compound Molecular Pump got a sensor tuning error when the accumulative radiation dose reached to 73.8 MGy. As a result of a disassembly check, cause of the failure was determined to be a decreased movement of the shaft due to the deformation of epoxy resin for the mandrel. However, all other parts such as the position sensor, the electromagnet and the motor, were no problem.     

Application of Macromonomers for Pressure Sensitive Adhesives II. Phase Separation and Adhesive Properties

Pressure sensitive adhesives (PSA) were prepared by copolymerization of butyl acrylate, methyl methacrylate and styrene macromer and the effects of macromer on the adhesive properties and phase separated structures were investigated. The results are as follows:

(1) The cohesion of the PSA increased as the quantity of the styrene macromer increased.

(2) The reason why the cohesion of the PSA increased seemed to be that the polystyrene phase, as the graft chain, was separated from the polybutyl acrylate phase as matrix.

(3) When styrene was used instead of styrene macromer, there were not these effects on the adhesive properties.     

Degradation analysis of dye-sensitized solar cell module after long-term stability test under outdoor working condition

Using Raman spectroscopy in addition to electrochemical impedance spectroscopy, we have clarified the deteriorated components of dye-sensitized solar cells (DSCs) module after the longest durability test in the world under outdoor working condition for ～2.5 years. It was confirmed that the N719 dye-adsorbed TiO₂ electrode and carbon counter electrode were almost stable; therefore, the photocurrent (Jsc) was maintained during the outdoor working. The photovoltages (Voc) and the filling factors (FF) slightly decreased due to the increase of the Nernst diffusion impedance of triiodide (I₃^?), resulting from the change of the components in the electrolyte.     

Characterization of random and multiblock copolymers of highly sulfonated poly(arylene ether sulfone) for a proton‐exchange membrane

Random and multiblock copolymers of sulfonated poly(arylene ether sulfone) (SPAES) were synthesized and characterized to compare the differences in the properties of proton‐exchange membranes made with random and multiblock SPAES copolymers. Atomic force microscopy observations and small‐angle X‐ray scattering measurements suggested the presence of nanoscale, clusterlike structures in the multiblock SPAES copolymers but not in the random SPAES copolymers. Proton‐exchange membranes were prepared from random and multiblock copolymers with various ion‐exchange capacities (IECs). The water uptake, proton conductivity, and methanol permeability of the SPAES membranes depended on the IECs of the random and multiblock SPAES copolymers. At the same IEC, the multiblock SPAES copolymers exhibited higher performances with respect to proton conductivity and proton/methanol permeation selectivity than the random SPAES copolymers. The higher performances of the multiblock SPAES copolymers were thought to be due to their clusterlike structure, which was similar to the ionic cluster of a Nafion membrane. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Combination of reinforcing powders and matrix alloys for fabrication of aluminum matrix composites by plasma synthesis method

Several kinds of powders and aluminum alloys are adopted to study the feasibility of the fabrication of aluminum matrix composites through plasma synthesis. Some powders do not incorporate into the molten aluminum due to reflection on the melt surface and dissolution in the plasma arc. On the contrary, iron powders are well incorporated into the molten aluminum. The iron powders incorporated into the molten aluminum make angular Al₁₃Fe₄ intermetallic compounds in the matrix. In addition, some portion of iron powders dissolve into the matrix and change the microstructures of the matrix alloys. The effects of dissolved Fe on the microstructures and mechanical properties of the composites are examined.     

Sulfidation kinetics and scale structures of chromium at temperatures of 973–1173 K and 104–10−6 Pa sulfur pressures

The sulfidation behavior of chromium was investigated over a temperature range of 973–1173 K in H₂S-H₂ gas mixtures of 10⁴–10^–6 Pa sulfur partial pressures using thermogravimetry, X-ray diffractometry, optical and scanning electron microscopy, and electron-probe microanalysis. Sulfidation kinetics are rapid for short periods and obey a linear rate law at low sulfur pressures, whereas at high sulfur pressures sulfidation tends to be parabolic. The surface morphologies can be divided into four types: at high sulfur pressures a petal-like crystal of Cr₂S₃(rho. and tri.) (type 1), at intermediate sulfur pressures a twinlike structure of Cr₃S₄ (type 2), at low sulfur pressures a flat surface with numerous hexagonal pits of Cr_1–xS (type 3), and a fine twinlike structure of ordered Cr_1–xS (type 4). At 973 K, the sulfur pressure ranges are type 1 at > 10^–4, type 2 at , and type 3 at . The critical sulfur pressure where type 2 was formed, 10^–5 Pa at 973 K, shifts toward higherressures at higher temperatures and becomes 10^–3 Pa at 1073 K and 10^–1 Pa at 1173K. Type 4 is observed at 1173K and 10^–6 Pa sulfur pressure. Thesulfide scale is composed of two distinct layers: an external layer, which is dense with a fine columnar structure, and an inner layer, which is porous with a layered structure of sulfides and voids. The external scale is composed offour layers at high sulfur pressures: at the scale-gas interface Cr₂S₃(rho.), next Cr₂S₃(tri.), third Cr₃S₄, and innermost Cr_1–xS. With decreasing sulfur pressures,the number of layers in the external scale was reduced. Pt markers were positioned between the external and inner scales.Emeritus Professor.     

Encapsulation of hemoglobin in mesoporous silica (FSM)-enhanced thermal stability and resistance to denaturants

Hemoblogin (Hb), which is a typical oligomeric protein, was introduced into the pores of mesoporous silica (FSM: folded-sheet mesoporous material) that had a diameter of 7.5 nm. Soret CD spectra of Hb-FSM-7.5 conjugates showed a peak that was identical to that of free Hb. This suggests that Hb retained its highly ordered structure in the mesoporous silica. In addition, the UV-visible absorption spectrum showed that Hb had an increased resistance to heat denaturation in the silica. Even after heat treatment at 85 degrees C, Hb-FSM-7.5 retained its ligand-binding activity. The stability of Hb-FSM-7.5 was examined further by measuring its peroxidase-like activity. Encapsulation of Hb resulted in the retention of activity in the presence of high NaCl or Gdn-HCl levels. This suggests that encapsulation prevented dissociation and denaturing. Thus, it seems that the mesopores created a favorable environment for the oligomeric protein to perform its function, even under harsh conditions.     

Transport of organic acids through a supported liquid membrane driven by lipase-catalyzed reactions

We have developed a lipase-facilitated supported liquid membrane. Lipase-catalyzed reactions were coupled with a supported liquid membrane (SLM) to transport organic acids through the SLM. We succeeded in the rational transport of organic acids through the SLM using lipase-catalyzed reactions and observed that there were differences in the transport behavior of various organic acids due to the substrate specificity of lipase. Subsequently, various parameters, such as the alcohol concentration in the feed phase, the pH in each aqueous phase, an organic solvent in the SLM, and the kind of lipase, were investigated. We found that the optimum conditions were 65 vol% alcohol concentration, pH 6.3 in each aqueous phase, isooctane as the liquid membrane phase and Candida rugosa lipase as the esterification biocatalyst.     

Change in electrical resistivity of nuclear graphite during compression tests and a model for its deformation and fracture mechanism

The results of the resistivity changes during compression of some nuclear graphites are summarized in order to cast light on the fracture mechanism of the materials; data on pyrolytic graphite and amorphous carbon are also taken into account. It is found that all the graphites investigated show an abrupt increase in resistivity when the applied stress increases to about a half of the fracture stress. Above this stress the non-linearity of the stress-strain curve becomes more pronounced and the formation and growth of optically resolvable cracks occur. A model based on the deformation of cracks and pores on the basal plane is proposed for explaining the change in resistivity, and is supported by measurements of the effect of pre-stressing on the Young's modulus, thermal expansion, mercury porosimetry and Knoop micro-hardness of the material.     

Cellular proteins of Microcystis aeruginosa inhibiting coagulation with polyaluminum chloride

Cyanobacterial growth in semi-closed water areas such as reservoirs brings about a coagulation inhibition in a drinking water treatment system, but the inhibitory substances and mechanisms involved have yet to be elucidated. In this study, proteins having a high affinity with polyaluminum chloride (PACl) were isolated from organic substances produced by Microcystis aeruginosa with the affinity chromatography technique. Both extracellular organic matter (EOM) and cellular organic matter (COM) disturbed the flocculation of suspended kaolin with PACl, but it was likely that nonproteinous substances in EOM cause the reduction of coagulation effciency. In contrast, proteins in COM were obtained as possible inhibitory substances for the coagulation with PACl. These proteins could consume PACl in the coagulation process due to the formation of chelate complexes between these inhibitory proteins and the coagulant. The consumption of PACl by cyanobacterial proteins could be one of the important causes of the increase in coagulant demand.