Seminatural Occurrence of Fullerenes

In continuation to our search of fullerenes in usual soots, sixteen additional samples of Chinese ink stick have been analyzed by HPLC. When combined with our previous results, we recognize that C₆₀-content in Chinese ink sticks decreases with time following the first order rate law. This novel observation was interpreted in terms of diffusion-dissipation of C₆₀ molecules through the solid stick.     

High Field Magnetism of the Spinel Oxide CoAl2O4

We report the results of magnetization and electron spin resonance (ESR) measurements on sintered samples of the spinel oxide CoAl₂O₄ in magnetic fields up to 53 T. In CoAl₂O₄, Co²⁺ (S=3/2) ions make a diamond lattice, indicating naively that no geometrical frustration takes place. This spinel oxide, however, is thought to be in the vicinity of a quantum melting point of the antiferromagnetically ordered state because of no sharp peak in the temperature dependence of specific heat. Magnetization curve at 4.2 K is almost linear in magnetic fields and a broad ESR signal was observed on a straight resonance line with g=2.26, implying an antiferromagnetic long range order or a well developed antiferromagnetic short range order with very small anisotropy.     

Internal moisture evolution in timbers exposed to ambient conditions following kiln drying

This study aimed to investigate the changes of internal moisture content distribution within hem-fir timbers after kiln drying while exposed to two different local outdoors seasonal conditions. Timbers were dried to three different target moisture contents (12, 17, and 22 %) and thereafter, they were conditioned outdoors in two diverse seasonal coastal environments, namely, cold-wet wintertime and warm-dry summertime. Moisture contents at quarter-point and the center in depth were continuously monitored for a period of 3 weeks. The results showed that no significant moisture content reductions took place during the cold-wet season equalization, while moisture content differences were regularly reduced regardless of seasonal conditions. In addition, below 2.5 % differential moisture content, moisture movement between at quarter-point and the center slowed down regardless of seasonal condition or current moisture content level. At high drying target moisture content of 22 %, moisture content values both at quarter-point and the center remained constant after 2 weeks at moisture content difference value of 2.5 %, and no further drying or no further moisture content equalization were observed after that point.     

Induction of the imbalance of helper T-cell functions in mice exposed to diesel exhaust

Administration of diesel exhaust particles (DEP) increases antigen-specific IgE production and IgE-secreting cells, and induces Th2-type cytokine profiles in the airway in mice and humans. To determine the early effects of diesel exhaust (DE) inhalation on the cytokine production profile, BALB/c mice were exposed to 0 (controls) and 1.0 mg/m3 DE inhalation for 4 weeks. Intraperitoneal sensitization with ovalbumin (OVA) was conducted immediately before DE inhalation. Mice were treated with anti-CD4 or anti-CD8 mAb 1 day before and after the sensitization. On day 21, these mice were boosted with OVA and blood; bronchoalveolar lavage (BAL) fluid, and spleens were collected on day 28. In BAL fluid, both TNFalpha and IL-10 production in DE-exposed and control mice remained basically the same. IL-6 production in the anti-CD4 treatment group of DE-exposed mice, however, significantly increased compared with that of the controls. In vitro antigen-stimulated interleukin-4 (IL-4) and -10 (IL-10) production in spleen cells of exposed mice were not affected by low-dose DE inhalation. In vitro interferon (IFN)-gamma production in the anti-CD4 treated group of exposed mice decreased markedly. Although anti-OVA IgE production in the plasma of sham-treated mice exposed to DE was the same level as for controls, anti-CD4 mAb treatment in DE-exposed mice significantly reduced IgE production compared to controls. In anti-OVA IgG1 production, anti-CD4 or anti-CD8 mAb treatment in DE-exposed groups also significantly reduced. Anti-OVA IgG2a production was reduced by treatment with anti-CD4 mAb, but increased by anti-CD8 mAb treatment in DE-exposed mice. Low dose DE inhalation is thus shown to adversely affect the cytokine and antibody production in mice by altering CD4+ and CD8+ T-cell functions.     

Ge-doped InxGa1−xAs p−n junctions

The amphoteric properties of Ge in the In_xGa_1?xAscrystals grown by liquid-phase epitaxy are reported. It was found from the Hall measurements that when x < 0·1, the Ge-doped In_xGa_1?xAs was p-type, and when x > 0.1,it was n-type . At the vicinity of x = 0.1, therefore, the In_xGa_1?xAs p?n junction could be made by one growth process. The electrical and photoelectric characteristics of that junction were investigated. The distribution of Ge concentration at the p?n junction, which was obtained from the C-V characteristics, depended on the doping concentrations of Ge. This dependence can be interpreted by analyzing a modified Longini-Green equation. The spectral responses of both photovoltaic effect and electroluminescence showed that in In_0.1Ga_0.9As, Ge atoms gave rise to a heavy compensation effect, and introduced a conduction band tail of states and two kinds of acceptor levels located ～ 20and～ 100meV above the valence band edge.     

High performance in protease refolding by application of a continuous system using immobilized inhibitor

In the reoxidative refolding of Streptomyces griseus trypsin, which is a serine protease having three S-S bonds per molecule, a synthetic inhibitor immobilized on agarose beads was applied in order to avoid the digestion of non-renatured protease molecules by renatured ones. A semi-continuous refolding system was fabricated by packing such inhibitor-immobilized gels in a glass column and the optimal operating conditions were investigated. Taking account of the effective conditions surveyed in the system, a continuous refolding system was constructed and operated to achieve higher performance. By application of the continuous system, a marked increase in the recovery rate as well as high recovered activity could be accomplished, i.e., the recovery rate obtained was ca. 40 times higher than that in the semi-continuous system. This system was also revealed to be substantially advantageous since it includes not only effective refolding but also separation, purification and enrichment processes in one operation.     

Three-dimensionality of field-induced magnetism in a high-temperature superconductor

Many physical properties of high-temperature superconductors are two-dimensional phenomena derived from their square-planar CuO2 building blocks. This is especially true of the magnetism from the copper ions. As mobile charge carriers enter the CuO2 layers, the antiferromagnetism of the parent insulators, where each copper spin is antiparallel to its nearest neighbours, evolves into a fluctuating state where the spins show tendencies towards magnetic order of a longer periodicity. For certain charge-carrier densities, quantum fluctuations are sufficiently suppressed to yield static long-period order, and external magnetic fields also induce such order. Here we show that, in contrast to the chemically controlled order in superconducting samples, the field-induced order in these same samples is actually three-dimensional, implying significant magnetic linkage between the CuO2 planes. The results are important because they show that there are three-dimensional magnetic couplings that survive into the superconducting state, and coexist with the crucial inter-layer couplings responsible for three-dimensional superconductivity. Both types of coupling will straighten the vortex lines, implying that we have finally established a direct link between technical superconductivity, which requires zero electrical resistance in an applied magnetic field and depends on vortex dynamics, and the underlying antiferromagnetism of the cuprates.     

Morphological changes in twisted nylon monofilament

The changes in structure of oriented nylon monofilaments due to an applied twisting action was investigated using wide angle x-ray scattering analysis and microscopy. The surface layer of the twisted filaments changes to a single texture after being repeatedly twisted in one direction at high temperature. Simultaneously, kink bands were produced on their surface. Characteristic features of kink bands are observed on the surface layer of the filaments first twisted in one direction and then twisted in the opposite direction at high temperature. X-ray diffraction patterns of the surface layer also changed remarkably. These changes in surface layers are related to the twist direction, the repeated number of twists, and the temperature of untwist. At lower temperatures, kink bands are not formed and a structural change to a single texture does not occur spontaneously.