Phase relationship on Mo-S system at high temperatures

Changing the partial pressure of sulfur Ps₂ at temperatures of 750° and 950°C, phase equilibria on the Mo-S system by solid-gas reaction were investigated. Hexagonal 2H-MoS₂ and monoclinic Mo₂S₃ phases were identified from the x-ray powder diffraction pattern. The 2H-MoS₂ had a slight homogeneity range, i.e. MoS_1.978 to MoS_2.0 at 950°C, MoS_1.983 to MoS_2.0 at 750°C. No remarkable variation of lattice parameters for the MoS₂ was observed. The composition of the Mo₂S₃ phase was not stoichiometric MoS_1.5 but MoS_1.457 at 950°C. At 750°C the composition of the Mo₂S₃ phase could not be determined since it was quite difficult to establish the equilibrium state between the gas and the condensed phases. This finding agreed well with the result of Morimoto and Kullerud.     

Factors affecting the oxidative activity of laccase towards biphenyl derivatives in homogeneous aqueous-organic systems

Catalytic oxidation of biphenyl derivatives was investigated using laccase in a homogeneous aqueous-organic system. A thermostable laccase from Trametes sp. showed the highest catalytic activity for the oxidation of 4-hydroxybiphenyl (4-HB) at a reaction temperature of 60 degrees C when dimethylsulfoxide (DMSO) was employed as a co-solvent. Furthermore, the catalytic performance was successfully enhanced by the incorporation of a laccase mediator system (LMS) into the aqueous-DMSO media. The catalytic performance strongly depended on the type of mediator, and the highest activity was observed with 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) as mediator, suggesting the importance of the selection of a suitable mediator. It was verified that this mediator system is applicable to the oxidation of several biphenyl derivatives with hydroxyl groups.     

HVEM study of crack-tip dislocations in Si crystals prepared by FIB and twin-blade cutting method

Crack-tip dislocations in silicon crystals have been examined by using high-voltage electron microscopy. Cracks were introduced by the Vickers indentation method at room temperature and the indented specimens were annealed at high temperatures to induce dislocations around crack tips under the presence of residual stress due to the indentation. A selected area around a crack tip was thinned by a focused ion beam (FIB) technique. Specimens were thinned in advance by a twin-blade cutting (TBC) method, which is a simple cutting process for saving FIB machine time. A combination of FIB and TBC can be a useful thinning procedure for the efficient preparation of transmission electron microscopy specimens. Characteristic dislocation structures were observed around the tip of a crack, aiding the elucidation of dislocation processes, which is essential to increase the fracture toughness of materials.     

Development of porous ceramics with well-controlled porosities and pore sizes from apatite fibers and their evaluations

Porous hydroxyapatite (HAp) ceramics possessing well-controlled porosities and pore sizes were developed by firing apatite-fiber compacts mixed with carbon beads and agar. The total porosities could be controlled in the range from 40 to 85% by varying compaction pressure (20-40 MPa), firing temperature (1000-1300 degrees C) and carbon/HAp ratio (0/10-10/10 (w/w)). Most of the pores were regarded as open pores. The pore sizes were mainly affected by the carbon-bead diameter (5, 20 or 150 microm) and partly by the compaction pressure and the firing temperature. The pore sizes of the porous HAp ceramics derived from the carbon beads of 150 microm in diameter were distributed in the two separate ranges of several micrometers and more than 100 microm.     

Self-assembly of a silica-surfactant nanocomposite in a porous alumina membrane

A mesoporous membrane composed of nanochannels with a uniform diameter has a potential use for precise size-exclusive separation of molecules. Here, we report a novel method to form a hybrid membrane composed of silica-surfactant nanocomposite and a porous alumina membrane, by which size-selective transport of molecules across the membrane becomes possible. The nanocomposite formed inside each columnar alumina pore was an assembly of surfactant-templated silica-nanochannels with a channel diameter of 3.4 nm; the channel direction being predominantly oriented along the wall of the columnar alumina pore. Molecules could be transported across the membrane including the silica-surfactant nanocomposite with a capability of nanometre-order size-exclusive separation. Our proposed membrane system has a potential use not only for separation science, but also catalysis and chip technologies.     

The influence of a fibre structure on optical loss in a graded-index fibre

For designing a fibre structure, the influence of structural parameters on optical loss is investigated experimentally for a graded-index fibre. The fibre with large cladding/outer-layer index difference and small cladding thickness is found to have large excess loss near excitation points, such as a launching point and a splicing point.     

Liquid holdup and heat transfer coefficient between bed and wall in liquid solid and gas-liquid-solid fluidized beds

In fluidized beds of 0.052 and 0.12 m i.d. air, water and aqueous solutions of carboxymethyl cellulose (viscosity = 9.0 X 10^-4- 52 X 10^-2 Pa s), and glass beads were used as gas, liquid and solid phase, respectively. The diameters of the glass beads were 4.2 X 10^-4 6.6 X 10^-4 1.2 X l0^-3, and 2.2 X 10^-3 m.The liquid holdup in the gas-liquid-solid fluidized bed was well correlated by modifying the Garside and Al-Dibouni's equation with the gas phase Froude number.The wall heat transfer coefficient of the gas-liquid-solid fluidized beds in the range of stable fluidization state runs correlated as a function of modified Nusselt number, modified Reynolds number and gas phase Froude number.     

Observation of New Longitudinal and Transverse Josephson Plasma Modes in the Parallel Magnetic Fields: Underdoped YBCO

Josephson plasma reflectivity edge in YBa₂Cu₃O_6.6 (T _c=59 K) was measured in parallel magnetic fields HCuO₂ up to 7 T. Upon application of the field, the Josephson plasma edge splits to two reflectivity edges, forming a new peak at finite frequency. Optical conductivity obtained by Kramers–Kronig analysis indicates that a new transverse Josephson plasma mode appears under parallel fields. We propose that the new mode originates from the modulation of the insulating layers with and without Josephson vortices, as has been suggested by free-energy calculations of Josephson vortices with moderate densities.     

2-Aminoethoxydiphenyl borate (2-APB) inhibits capacitative calcium entry independently of the function of inositol 1,4,5-trisphosphate receptors

Capacitative calcium entry (CCE), the mechanism that replenishes intracellular calcium stores after depletion, is essential to intracellular calcium signaling. CCE is mediated by the channels in the plasma membrane generally referred to as "store operated channels (SOCs)". However, the molecular identity of the SOCs has never been determined, and the mechanism of the activation of SOCs remains to be elucidated. Recent studies have demonstrated that 2-aminoethoxydiphenyl borate (2-APB), which has been found to be an antagonist of inositol 1,4,5-trisphosphate receptors (IP3Rs), inhibits CCE, suggesting that IP3Rs channel activity is essential to the generation of CCE. However, CCE has also been reported to occur normally in IP3R-deficient cells. In order to resolve this discrepancy, we investigated the effect of 2-APB on CCE in IP3Rs-deficient cells. In response to store depletion with thapsigargin or N,N,N',N'-tetrakis (2-pyridylmethyl) ethylene diamine (TPEN), CCE was generated in IP3Rs-deficient cells the same as in wild-type cells, however, 2-APB abolished CCE in IP3Rs-deficient cells, despite the fact that this cell line does not possess functional IP3Rs. We also examined the effect of 2-APB on several types of TRP Ca2+ channels, which exhibit properties similar to those of SOCs. 2-APB had a different inhibitory effect on spontaneous and thapsigargin-induced Ba2+ influx in cells that transiently expressed individual TRP subtypes. These results suggest that the channel activity of IP3Rs is not essential to the generation of CCE in this cell line and that 2-APB inhibits CCE independently of the function of IP3Rs.