Adsorption Potentials and Film Growths of 4He in Nanometer Pores of FSM-16 (2.8 nm) and HMM-2 (2.7 nm)

No Heading To find the one- and the three-dimensionalities for the superfluid onset of the ⁴He films formed in nanopores, we have been studying ⁴He adsorbed on FSM-16 and HMM-2 that have pores of almost the same diameter, 2.8 and 2.7 nm, but ID and 3D connections of the pores, respectively. For these two substrates, the adsorption potential profile and layer-by-layer growth of ⁴He films were observed by the precise measurement of the vapor pressure for adsorption. The isothermal compressibility _T, the film thickness d, and the isosteric heat q_st of adsorption are derived from the vapor pressure. _T and d indicate that ⁴He adatoms form uniform layers up the second layer on both substrates. Almost the same q_st for both substrates suggest that the adsorption potential is the same between these SiO₂-based substrates. These results suggest that FSM-16 and HMM-2 are ideal substrates to use in investigating the dimensionality of the superfluid onset.PACS numbers: 67.40.–w, 67.70.+n     

Oxidative Decomposition of N,N'-Dimethylformamide over Pt Catalysts with H2 Addition to the Feed

Catalysis of decomposition of dilute N, N'-dimethylformamide was explored. Among the catalysts investigated, Pt displayed the highest activity at low temperatures (~200 °C) and DMF conversion was promoted by H₂ addition to the feed. As the Pt support material, H-ZSM-5 exhibited the best performance at around 200 °C in terms of harmless decomposition.     

Thermally stimulated current studies on molecular relaxation and blow moulding of poly(ethylene terephthalate)

The thermally stimulated current (TSC) technique has been used to investigate molecular relaxation in poly(ethylene terephthalate) (PET) films unstretched and biaxially stretched at 90 and 95 °C. Unstretched PET films show two peaks at 77 and 90 °C corresponding to α and ρ relaxation processes, respectively. The α relaxation is associated with the main glass transition of the material. The ρ peak with lower intensity is attributable to permanent dipoles. Both biaxially stretched samples show one TSC peak at 95 °C, supposed to correspond to ρ relaxation. The disappearance of the α peak, accompanied by the displacement of the ρ peak to higher temperature, is the result of the higher thermal stability of the permanent dipoles, which is strongly influenced by the stiffening of amorphous parts and the crystallization by stretching. In both stretched samples, the continuous distribution of pre-exponential factors over activation energies observed might correspond to a single relaxation mode. The kinematics of stretching PET has been discussed in terms of activation energy and temperature dependence of relaxation time. © 1999 Society of Chemical Industry     

Polypeptide Compositions and Antigenic Homologies Among Prolamins from Italian,Common and Japanese Millet Cultivars

Prolamins from Italian, common and Japanese millet cultivars were separately extracted with three kinds of alcohol (ethanol, propanol and isopropanol) and their component polypeptides and immunochemical relationships were examined by SDS-PAGE, two-dimensional electrophoresis and immunoblot analysis using the antiserum raised against Italian millet prolamin. Polypeptides of the individual millet prolamins appeared to be primarily composed of two major common subunit complexes with respective molecular masses ranging from about 19 to 23 kDa and from 13 to 14 kDa (groups A and B, respectively), although a few minor variations due to varietal differences were seen. Group A clearly contained one neutral subunit (21 kDa) and one basic one (22 kDa), while group B had one basic 14 kDa subunit. The Italian millet prolamin antiserum strongly bound with all three prolamin polypeptides but neither with the homologous non-prolamin fractions nor with the heterogeneous prolamins of the Triticeae (wheat, barley and rye). Amino acid compositions were found to be almost identical to one another.     

Shape-controlled synthesis of hydroxyapatite from α-tricalcium bis(orthophosphate) in organic-aqueous binary systems

Hydrolyses of -tricalcium bis(orthophosphate) Ca₃(PO₄)₂ (-TCP) were carried out in a heterogeneous solvent system (hydrophobic organic solvent-water). The hydroxyapatites (HAp) formed were deficient in calcium (Ca/P = 1.56–1.61, a-axis = 0.9440 nm, c-axis = 0.6880 nm) and contained acid phosphate (and sometimes carbonate depending on the organic solvent used). The HAp was in the form of needles with a length (1–4 m) that depended on the polarity of the hydrophobic organic solvent. The aspect ratio was highest in 1-octanol with a polarity of E _T = 48.3. On the other hand, in a hydrophobic organic solvent system without OH groups such as n-octane (E _T = 31.1), HAp formed fine particles that are similar to HAp prepared in a system without an organic solvent. Thus, hydrophobicity and OH groups of organic solvents affect the crystal growth of HAp.     

Formation of L10-type ordered β′ phase in as-solutionized dental Ag-Pd-Au-Cu alloys and hardening behavior

The relationship between the microstrucutural changes of L1₀-type ordered β′ phase and hardening behavior in as-solutionized dental Ag-Pd-Au-Cu alloys was investigated by changing the cooling rate and the solution treatment temperature. Additionally, the formation process of the β′ phase in as-solutionized Ag-Pd-Au-Cu alloy was attempted to clarify. The microstructural changes were observed by X-ray diffraction (XRD) method and transmission electron microscopy (TEM). The hardness was evaluated using a Vickers microhardness tester. The β′ phase is precipitated regardless of the cooling rate, after solution treatment at 1123 K. TEM dark field images show that the size of the β′ phase decreases and the number of β′ phase increases with an increase in the cooling rate. The Vickers hardness value increases with an increase in cooling rate. TEM dark field images show that the microstructure of β′ phase is similar when the solution treatment temperature increases from 1123 K to 1173 K. However, the Vickers hardness increases with an increase of solution treatment temperature. It is of great significance to reveal that the β′ phase precipitated in as-solutionized Ag-Pd-Au-Cu alloy is formed during cooling after high-temperature solution treatment and that the growth of the β′ phase is diffusion controlled.     

Preparing samples for fullerene C60 hazard tests: Stable dispersion of fullerene crystals in water using a bead mill

A dispersion method using a bead mill was developed for preparing suspensions used in hazard testing of nanosize fullerenes. Fullerene crystals (C₆₀) of several μm to 100 μm in size were wet ground using a bead mill and dispersed in pure water containing Tween 80 as a dispersant. The particle size, dispersing condition, crystallization and fullerene oxide in the suspension prepared by bead milling were evaluated. As a result, the conditions of bead milling where the sizes of fullerene crystals were reduced to 100 nm or less were found, which made it possible to prepare a fullerene aqueous dispersion system using Tween 80. Furthermore, by centrifugation, it became possible to prepare fullerene suspensions in which the particle size of the majority of the suspended particles was 100 nm or less. The prepared suspensions remained stable for almost two months. Controlling milling conditions and milling time made it possible to achieve dispersion while maintaining the crystallized state of the fullerenes, and operating in anaerobic conditions under shade effectively suppressed the production of oxidized fullerenes. The fullerene suspensions prepared by bead milling and centrifugation were suitable for endotracheal administration tests and inhalation tests using rats.     

Competition Between the Superfluid Overlayer and the Mobile Solid Layer of 3He-4He Mixture Films on Porous Gold

In the previous quartz crystal microbalance measurements for ⁴He films adsorbed on porous gold, we have observed a competition between superfluidity and slippage: In low areal densities, the resonance frequency increases gradually below T _S due to the slippage of solid layer, while at high areal densities the slippage disappears and the superfluid onset of liquid overlayer is observed at T _C . In the crossover region, the slippage below T _S is suddenly suppressed at T _D , which is much lower than T _C . In the present work, we introduced a small amount of ³He onto ⁴He films, and studied the competition as a function of ³He areal density ρ ₃. As ρ ₃ is increased, T _C is monotonically lowered. In contrast, T _D increases up to a certain value of ρ ₃, and then turns over to decrease in parallel to T _C .     

Photocatalytic degradation of organic compounds diluted in water using visible light-responsive metal ion-implanted TiO2 catalysts: Fe ion-implanted TiO2

The application of metal ion-implantation method has been made to improve the electronic properties of the TiO₂ photocatalyst to realize the utilization of visible light. The photocatalytic properties of these unique TiO₂ photocatalysts for the purification of water have been investigated. By the metal ion-implantation method, metal ions (Fe⁺, Mn⁺, V⁺, etc.) are accelerated enough to have the high kinetic energy (150 keV) and can be implanted into the bulk of TiO₂. TiO₂ photocatalysts which can absorb visible light and work as a photocatalyst efficiently under visible light irradiation were successfully prepared using this advanced technique. The UV-Vis absorption spectra of these metal ion-implanted TiO₂ photocatalysts were found to shift toward visible light regions depending on the amount and the kind of metal ions implanted. They were found to exhibit an effective photocatalytic reactivity for the liquid-phase degradation of 2-propanol diluted in water at 295 K under visible light (λ>450 nm) irradiation. The investigation using XAFS analysis suggested that the substitution of Ti ions in TiO₂ lattice with implanted metal ions is important to modify TiO₂ to be able to adsorb visible light.