Experimental confirmation of the isotopic volume effect in superconducting molybdenum by means of energy-dispersive x-ray diffration at low temperatures

Differences in the lattice constants of Mo-100 and Mo-92 have been measured by x-ray diffraction, in order to search directly for the volume effect of isotopes in a superconductor. No significant difference in the lattice constanta(Mo-100)–a(Mo-92) could be detected at 290 K, while the differences –0.0014±0.0008 and –0.0029±0.0009 Å were detected at 85.3 and 4.31 K, respectively. These values, and their temperature dependence, are considered to be theoretically reasonable. The exponent in the isotope effect defined by T_cM^- is represented thermodynamically by =–( lnT _c / lnM)–( lnT _c / lnV)(d lnV/d lnM). From the results, d lnV/d lnM is found to be –0.033±0.009 at 4.31 K. Then, the second term representing the isotopic volume effect is estimated to be about 0.09, with lnT _c / lnV2.81. The observed value of is 0.33, so that the contribution of the second term, 0.09, is 27% of the value of . It becomes quite clear that the isotopic volume effect in superconducting Mo should not be neglected.     

Multinomial Bayesian learning for modeling classical and nonclassical receptive field properties

We study the interplay of Bayesian inference and natural image learning in a hierarchical vision system, in relation to the response properties of early visual cortex. We particularly focus on a Bayesian network with multinomial variables that can represent discrete feature spaces similar to hypercolumns combining minicolumns, enforce sparsity of activation to learn efficient representations, and explain divisive normalization. We demonstrate that maximal-likelihood learning using sampling-based Bayesian inference gives rise to classical receptive field properties similar to V1 simple cells and V2 cells, while inference performed on the trained network yields nonclassical context-dependent response properties such as cross-orientation suppression and filling in. Comparison with known physiological properties reveals some qualitative and quantitative similarities.     

Formation of Anatase Porous Ceramics by Hydrothermal Hot-Pressing of Amorphous Titania Spheres

Anatase porous ceramics were produced at low temperatures below 350°C by hydrothermal hot-pressing of amorphous titania consisting of spherical particles prepared by hydrolysis of titanium tetraethoxide. After fine anatase crystals were formed in the original amorphous spheres by hydrothermal hot-pressing, the spherical particles were deformed and the fine anatase crystals flowed into the interstices among the original spheres by compression from outside the autoclave to form a compact with homogeneous distribution of fine pores. The fine anatase crystals in the compacts were bonded together by dissolution and deposition to form a compact with high mechanical strength. The porous anatase ceramics with open pores were prepared by drying in air after removing water which had occupied the pores in the compacts during hydrothermal hot-pressing.     

Fabrication of Low-Porosity Indium Tin Oxide Ceramics in Air from Hydrothermally Prepared Powder

Compositionally homogeneous indium tin oxide (ITO) ceramics with low porosity were obtained successfully by sintering hydrothermally prepared powders. The fabrication technique began with the preparation of microcrystalline, homogeneously tin-doped (5 wt%) indium oxyhydroxide powder, under hydrothermal conditions. Low-temperature (∼500°C) calcination of the hydrothermally derived powder led to the formation of a substitutional-vacancy-type solid solution of In₂Sn_{1− x} O_{5− y} , and further heating of this phase at temperatures of >1000°C resulted in the formation of the tin-doped indium oxide phase, which had the C -type rare-earth-oxide structure. The sintering of uniformly packed, calcined powder compacts at 1450°C for 3 h in air resulted in low-porosity (∼0.7%) ITO ceramics.     

Possibilities of the Formation of Enol-Ethers in Lignin by Soda Pulping

In the alkaline decomposition of a β-O-4 type lignin model compound (erythro-guaiacylglycerol-β-guaiacyl ether, compound 1), an isomeric pair of C₆C₂ enol-ether (2-methoxy-4-[2-(2-methoxyphenoxy)-vinyl]-phenol, compound 2) was detected as the main decomposition product with no trace of C₆C₃ enol-ether (4-[3-hydroxy-1-(2-methoxyphenoxy)-propenyl]-2-methoxy-phenol, compound 3) or other dimers. In contrast, compound 2 was not detected in the alkaline decomposition products of compound 3. Under alkaline conditions, the γ-hydroxymethyl group of compound 3 was reduced to form 2-methoxy-4-[1-(2-methoxyphenoxy)-propenyl]-phenol (compound 4). In the HSQC analysis of soda lignin, the formation of substructures of C₆C₂ type enol-ether (related to compound 2) was confirmed. However, no substructures related to compound 4, which could be formed if a substructure of C₆C₃ type enol-ether was formed under alkaline conditions, were detected. Therefore, it could be concluded that C₆C₃ type enol-ethers could not be intermediates of alkaline decomposition products of lignin.     

An Application of Silica‐Based Monolithic Membrane Emulsification Technique for Easy and Efficient Preparation of Uniformly Sized Polymer Particles

Summary: Uniformly sized polymer particles were prepared by an emulsification and polymerization technique utilizing a silica monolithic membrane, namely the “silica monolithic membrane emulsification technique”. In this paper, we utilized silica monolithic membrane as a device for the preparation of uniformly sized polymer particles. A mixture of monomers, diluents and oil‐soluble initiator was emulsified into a continuous medium through the silica monolithic membrane and polymerized. The particles obtained had a higher size uniformity than that of particles prepared by previously reported membrane emulsification techniques, such as the Shirasu Porous Glass (SPG) emulsification technique. Through the silica monolithic membrane emulsification technique, we could prepare particles having availability as a possible packing material for solid‐phase extraction (SPE) and high performance liquid chromatography (HPLC).

SEM photograph of silica particles prepared through capillary plate membrane.     

Hydrolysis of Cellulose Selectively into Glucose Over Sulfonated Activated-Carbon Catalyst Under Hydrothermal Conditions

A sulfonated activated-carbon (AC-SO₃H) catalyst selectively hydrolyzes cellulose with β-1,4-glycosidic bonds into glucose in the catalytic hydrothermal reactions at temperatures around 423 K. The AC-SO₃H catalyst with the hydrothermal pre-treatment has the excellent catalytic properties attributed to the high hydrothermal stability and the strong acid sites of sulfo functional groups.     

Water vapor barrier property of organic-silica nanocomposite derived from perhydropolysilazane on polyvinyl alcohol substrate

Poly(vinyl alcohol) membrane was coated with organic-silica nanocomposite derived from perhydropolysilazane. For organic composite part, polystyrene-block-poly(4-vinyl phenol) [SP], poly(tert-butyl acrylate-co-2-hydroxyethyl methacrylate) [BA] and poly(butyl methacrylate-co-2-hydroxyethyl methacrylate) [BMA] were used. Water vapor barrier property of coat membrane was measured at relative humidity = 96% by a cup method. The coat films of nanocomposites with SP-silica and BA-silica showed better water vapor barrier property than those of the silica coat film without organic polymer and BMA-silica composites. The surface morphologies of the coat films were investigated by scanning electron microscopy and atomic force microscopy. The addition of organic polymer to silica prevented the crack formation of coat layer on the substrate.     

Performance of a monolithic silica column in a capillary under pressure-driven and electrodriven conditions

A continuous macroporous silica gel network was prepared in a fused-silica capillary and evaluated in reversed-phase liquid chromatography. Under pressure-driven conditions, the monolithic silica column derivatized to C18 phase (100 microns in diameter, 25 cm in length, silica skeleton size of approximately 2.2 microns) produced plate heights of about 23 and 81 microns at 0.5 mm/s with a pressure drop of 0.4 kg/cm2, and at 4.0 mm/s with 3.6 kg/cm2, respectively, in 90% acetonitrile for hexylbenzene with a k value of 0.7. The separation impedance, E, calculated for the present monolithic silica column was much smaller at a low flow rate than those for particle-packed columns, although higher E values were obtained at a higher flow rate. Considerable dependence of column efficiency on the linear velocity of the mobile phase was observed despite the small size of the silica skeletons. A major source of band broadening in the HPLC mode was found in the A term of the van Deemter equation. The performance of the continuous silica capillary column in the electrodriven mode was much better than that in the pressure-driven mode. Plate heights of 7-8 microns were obtained for alkylbenzenes at 0.7-1.3 mm/s, although the electroosmotic flow was slow. In HPLC and CEC mode, the dependency of plate height on k values of the solutes was observed as seen in open tube chromatography presumably due to the contribution of the large through-pores. Since monolithic silica capillary columns can provide high permeability, the pressure-driven operation at a very low pressure can afford a separation speed similar to CEC at a high electric field.     

Mutation analysis of the WT1 gene in myelodysplastic syndromes

Infectious mononucleosis due to Epstein-Barr virus (EBV) is almost always a self-limited disease, most commonly seen in young adults. Hepatitis is a well-recognized complication of EBV infection that usually resolves spontaneously. Jaundice occasionally results from the unusual complication of autoimmune haemolytic anaemia rather than hepatitis. We report a 60-year-old man with severe cholestatic jaundice whose history, liver histology and laboratory findings suggested EBV infection. He also developed significant jaundice related to his hepatitis, but not to autoimmune haemolysis, a situation that led to diagnostic delay. Costly diagnostic laboratory tests and invasive procedures were performed to rule out a malignant extrahepatic biliary obstruction. Physicians need to be aware of this complication and EBV infection should be included in the differential diagnosis of cholestatic jaundice in the elderly.