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Notes: It has been found that the exposure of a Si (100) surface to an As ionized cluster beam (ICB) is effective in the preparation of the surface prior to epitaxial growth of GaAs under conventional high vacuum conditions of 2×10−5 Pa. This process is achieved at a temperature as low as 600 °C. A clear 1×2 or 2×2 reflection high energy electron diffraction pattern observed after the procedure indicates good ordering of the sample surface. The cleaning process is attributed to chemical and physical sputtering by As ICB in the first stage and to the subsequent As termination of Si dangling bonds. It has been found that the optimum preparation conditions are an accelerating voltage of the As ionized cluster beam of 1.3 kV and a substrate temperature of 600 °C. GaAs films deposited on As ICB treated Si (100) substrates show good crystal quality with single domain structure.

Notes: Previous studies have shown that nanoparticle chain aggregates (NCA) of titania are elastic [S. K. Friedlander, H. D. Jang and K. H. Ryu, Appl. Phys. Lett. 72, 1 (1998)]. The NCA were a few tenths of a micron long and composed of (approximately) 7 nm primary particles. They were produced by thermal decomposition of titanium tetraisopropoxide vapor in nitrogen. The goal of this study was to see whether the elastic behavior depends on (a) the material properties, (b) primary particle size, and (c) method of NCA formation. For this purpose, titania, alumina, and iron oxide NCA were generated by laser ablation. Rotating metal foil targets were mounted in a small cylindrical chamber and exposed to an excimer laser beam. The resulting aerosol was swept out by an oxygen stream. The generator was operated to produce NCA with similar mobility diameter and primary particle size. The NCA were deposited on the carbon or formvar films of an electron micrograph grid. Under the electron beam a hole develops in the carbon film in the neighborhood of the deposited NCA. The NCA then stretch and contract as described in our earlier study [S. K. Friedlander, H. D. Jang and K. H. Ryu, Appl. Phys. Lett. 72, 1 (1998)]. The titania, alumina, and iron oxide NCA generated by laser ablation all showed elastic behavior for primary particles smaller than about 10 nm. However, titania NCA composed of 36 nm primary particles did not exhibit elastic behavior indicating that very small primary nanoparticles are needed for this phenomenon to occur. The small scale stretching and contraction of chain segments were studied by measuring changes in the bond angles between adjoining particles and in the lengths of the segments studied. The elastic behavior is probably associated with local folding of chain segments due to van der Waals forces. Under tension, folded chains straighten but when the tension is relaxed, folds tend to reform but not reversibly. Rotation and sliding probably occur at the boundaries between particles during stretching. We hypothesize that elastic behavior is a general property of NCA composed of transition metal oxides with primary particles smaller than 10–15 nm; the phenomenon has now been observed for NCA produced in two ways, thermal decomposition and laser ablation. These phenomena may play a role in the action of nanoparticle additives such as fumed silica and carbon black used to improve the properties of rubber. NCA elasticity may also contribute to the ductile properties of nanoparticle compacts. © 2000 American Institute of Physics.

Notes: Blood flow stagnation is said to be an important factor for the incidence of dark eye circles, but there are few reports, which have studied dark eye circles and the relationship to blood flow. We have examined dark eye circles dermatologically using a non-invasive method and made clear the factor related to it. We have also studied the effect of newly developed cosmetics on improvement of dark eye circles. Melanin and haemoglobin content, haemoglobin oxygen saturation and blood flow rate were measured to compare dark eye circles with a normal control. An increased amount of haemoglobin and decreased haemoglobin oxygen saturation were observed at the site of dark eye circles. We also observed that the blood flow rate was slow at dark eye circles in comparison with cheek. From these results, blood flow stagnation seems to be one of the factors that could induce dark eye circles. In addition, the increase of melanin at dark eye circles was also observed in older subjects. It was considered that not only congestion but also an increase of melanin content in the skin could induce dark eye circles. On the basis of these results, we developed anti-dark eye circle cosmetics that can improve blood circulation, reduce melanin content and maintain high moisture retention in the skin. After 3 weeks’ usage of this product, it was confirmed that dark eye circles were improved, judging from the result of non-invasive instrumental measurements.

Notes: Needle-shaped quantum size microcrystals as thin as 10 nm have been selectively grown by employing reduced pressure organometallic vapor phase epitaxy using trimethylgallium and arsine as source materials. The microcrystals grown within a SiO2 window area have their growth axes along the [111] direction. Transmission electron diffraction analysis shows that the crystal structure of microcrystals is consistent with the zinc-blende structure of GaAs. The mechanism for growing the needle-shaped crystals is similar to a vapor-liquid-solid (VLS) equilibrium phase growth model. From photoluminescence measurements at 4.2 K, it is found that the microcrystals show a very distinct spectra for free exciton and neutral acceptor-bound exciton recombinations, meaning good crystal quality.

Notes: Fluctuations of magnetic fields and related magnetohydrodynamic (MHD) phenomena are investigated in the TPE-1RM15 reversed-field pinch experiment [Plasma Physics and Controlled Fusion Research, 1986 (IAEA, Vienna, 1987), Vol. 2, p. 453]. Mode analysis of fluctuations measured by multichannel coils reveals that nonlinear interactions between m=1 and m=0 modes, such as nonlinear coupling and phase locking, play significant roles during a dynamo event (i.e., the flux genertion process in the sustainment phase), resulting in transition from an unstable state to a stable state. Behaviors of these fluctuations are found to be toroidally asymmetrical due to strong nonlinearity. Study of the current ramping experiment shows that the inverse of global energy confinement time depends on the squared fluctuation level offset linearly, which is consistent with the prediction of the transport model based on the diffusion of stochastic field lines. By examining the dependence of the resistive part of the loop voltage on the fluctuation level, the input power to the electrons and ions are estimated to be about 70% and 30% of the total input power, respectively.

Notes: Background We have recently demonstrated that the transfer of interleukin (IL)-5-producing CD4+ T cell clones into unprimed mice is sufficient for the development of eosinophilic inflammation in the bronchial mucosa upon antigen inhalation.Objective The aim of this study was to elucidate the possible contribution of mast cells in eosinophilic inflammation and bronchial hyper-responsiveness (BHR), and to discriminate between the roles of CD4+ T cells and mast cells.Methods Mast cell-deficient mice (WBB6F1-W/Wv) and their congenic normal littermates (WBB6F1−+/+) were immunized with ovalbumin and challenged by inhalation with the relevant antigen.Results Airway eosinophilia was induced with equivalent intensity in +/+ and W/Wv mice 6, 24, 96 and 216 h after antigen inhalation. In contrast, 48 h after antigen challenge, eosinophilic infiltration into the bronchial mucosa was significantly less pronounced in W/Wv mice than in +/+ mice. Anti-CD4 monoclonal antibody (mAb), anti-IL-5 mAb, and cyclosporin A were administered next, demonstrating that the airway eosinophilia of W/Wv mice induced 48 h after antigen challenge was almost completely inhibited by each of these three treatments, but that of +/+ mice was significantly less susceptible. Bronchial responsiveness to acetylcholine was increased 48 h after antigen challenge and was not significantly different between +/+ and W/Wv mice. Administration of anti-IL-5 mAb completely inhibited the development of BHR in both +/+ and W/Wv mice.Conclusion These results indicate that, in mice, mast cells do have a supplemental role in the development of pulmonary eosinophilia but not BHR. CD4+ T cells totally regulate these responses by producing IL-5.

Notes: Myxobolus artus infection of carp is reported for the first time from Japan. In most cases, it took the form of interfibrillar pseudocysts in the skeletal muscle, some showing abnormal growth, imperfect encapsulation of the parasite by the host connective tissue and irregular development of the ectoplasm. Such atypical pseudocysts probably ruptured before the completion of sporogenesis, causing lysis of adjacent muscle fibres. Intrafibrillar pseudocysts were also present. After spore formation was complete or atypical pseudocytes were ruptured host reaction was initiated. Spores were phagocytosed and transported to the melanomacrophage centres in the kidney, liver, spleen etc. Phagocytosed spores were also observed in the capillaries and epithelial tissues of various organs, suggesting that the spores were transported there from the skeletal muscle through the host vascular system. They are thought to be discharged from the host through the skin and intestine.

Notes: The circulating antibody which reacted with sonicated spores of Myxobolus artus was detected in some naturally infected carp. However, some other fish had no detectable sign of infection, though they had the antibody. When carp were injected either with intact or sonicated spores, the antibody was not produced, while fish injected either with developing stages (presporogonic and sporoblast stages) of the parasite or sonicated spores with bovine serum albumin elicited the antibody production. The results of the injection experiments suggest that (1) developing stages have antigenicity to carp, and (2) spores have lost the antigenicity; sonicated spores are haptens, with which the antibody can react. In an indirect fluorescent antibody technique, sera positive for the antigen reacted with developing stages of the parasite, but not with the spore.The mechanism of the host immune response against M. artus is discussed in relation to a previous observation that the parasite sometimes underwent abnormal development, in which host encapsulation was imperfect or even lacking, probably leading to degeneration of pseudocysts before the completion of spore formation. It is plausible that the antibody was produced when pseudocysts which showed abnormal growth ruptured during their developing stages, resulting in exposure of the young parasite to the host immune system.