Effect of pre-oxidation on reactivity of chars in steam

The effects of pre-oxidation of char from Taiheiyo coal, a non-caking bituminous coal, in the 400–550 °C temperature range on its gasification reactivity with N₂-H₂O at 0.1 MPa (steam partial pressure of 13.2 kPa) have been investigated. The pre-oxidation of char markedly enhances gasification rates at temperatures between 800 and 900 °C. Reactivity is found to parallel the burn-off level during preoxidation at low temperatures (400–430 °C), whereas at relatively high temperatures (480–550 °C), the burn-off level only affects the reactivity slightly. The amount of CO and CO₂ evolved from the preoxidized char by heat treatment is proportional to the burn-off level at low temperatures (400–430 °C), being closely related to the enhancement of the gasification reactivity in steam.     

Study of crater formation and sputtering process with large gas cluster impact by molecular dynamics simulations

Molecular dynamics (MD) simulations of large argon clusters impacting on silicon solid targets were performed in order to study the transient process of crater formation and sputtering. The MD simulations demonstrate that the initial momentum of incident cluster is transferred to target surface atoms through multiple collision mechanism, where the initial momentum, which is along to the surface normal before impact, is deflected to lateral direction. This momentum transfer process was analyzed by the calculation of the velocity at the crater edge (the interface between cluster and target). In the case of Ar₁₀₀₀ cluster impact on Si(1 0 0) target at low energy per atom less than 40 eV/atom, the maximum value of lateral velocity of the crater edge increases in proportional to the velocity of incident cluster atoms. On the other hand, the crater edge velocity saturates over 40 eV/atom of incident energy per atom. In this case, the whole of constituent cluster atoms are implanted into the target and expand in both lateral and reflective directions at the subsurface region of the target. These MD simulations demonstrated that this collisional process result in the high yield sputtering of the target atoms.     

Treatment of Chronic Kidney Disease with Extracellular Vesicles from Mesenchymal Stem Cells and CD133+ Expanded Cells: A Comparative Preclinical Analysis

Chronic kidney disease (CKD) is characterized by structural abnormalities and the progressive loss of kidney function. Extracellular vesicles (EVs) from human umbilical cord tissue (hUCT)-derived mesenchymal stem cells (MSCs) and expanded human umbilical cord blood (hUCB)-derived CD133⁺ cells (eCD133⁺) maintain the characteristics of the parent cells, providing a new form of cell-free treatment. We evaluated the effects of EVs from hUCT-derived MSCs and hUCB-derived CD133⁺ cells on rats with CDK induced by an adenine-enriched diet. EVs were isolated by ultracentrifugation and characterized by nanoparticle tracking analysis (NTA) and electron microscopy. The animals were randomized and divided into the MSC-EV group, eEPC-EV group and control group. Infusions occurred on the seventh and 14th days after CKD induction. Evaluations of kidney function were carried out by biochemical and histological analyses. Intense labeling of the α-SMA protein was observed when comparing the control with MSC-EVs. In both groups treated with EVs, a significant increase in serum albumin was observed, and the increase in cystatin C was inhibited. The results indicated improvements in renal function in CKD, demonstrating the therapeutic potential of EVs derived from MSCs and eCD133⁺ cells and suggesting the possibility that in the future, more than one type of EV will be used concurrently.     

Growth of bubbles containing plasma in water by high-frequency irradiation

Plasma was generated in water by irradiation at high frequency of 13.56 MHz, and the behavior of bubbles including the plasma was observed by a high-speed camera. The generation pattern of the bubbles was classified into four types according to liquid temperature and supplied power. Conducting the simulation, the maximum temperature in the bubble was found to be from 3500 K to 4300 K, and the decomposition of water molecule occurred. The gas in the bubble was found to become high ratio of hydrogen. The phenomenon can be regarded as a film boiling of exceptionally high heat flux.     

Influence of Water on the Compression Behavior of Decomposed Granite Soil

In order to investigate the influence of water on compression characteristics of decomposed granite soils, single-particle crushing and one-dimensional compression tests were carried out on three types of decomposed granite soils as well as on quartz-rich silica sand under both dry and wet conditions. Results showed that the initial crushing strength of a single particle was reduced and strength variability increased due to the weakening effects induced by the presence of water. Moreover, it was observed that the one-dimensional compression behavior of decomposed granite soil was related to the initial crushing strength. Finally, the magnitude of initial crushing strength was also affected by the degree of weathering of the soil.     

Theoretical analysis of high-temperature characteristics of1.3-μm InP-based quantum-well lasers

By taking into account the electrostatic deformation in the band profiles and the temperature dependence of the optical dephasing time, we study the temperature sensitivity of the differential gain, threshold carrier density, and radiative current density in 1.3-μm InP-based strained-layer quantum-well (QW) lasers. Electrostatic deformation is analyzed by the self-consistent numerical calculation of Poisson's equation, the scalar effective-mass equation for the conduction band, and the multiband effective-mass equation for the valence band. The optical dephasing time is then obtained from the intrasubband scattering rates for electrons and holes within the fully dynamic random phase approximation including carrier-carrier and carrier-phonon interactions on an equal basis. It is clarified that the electrostatic band-profile deformation is one of the dominant mechanisms For determining the temperature sensitivity Of the differential gain, while the optical dephasing time has a pronounced influence on the transparent condition at elevated temperatures. We demonstrate that the electrostatic band-profile deformation and the temperature-dependent optical dephasing play essential roles in determining the high-temperature characteristics of InP-based QW lasers     

Effects of veterinary drugs on beta-hexosaminidase release from rat basophilic leukemia cells (RBL-2H3)

Little is known about the effects of residual veterinary drugs on the allergic reaction, except for the antigenicity of antibiotics and synthetic antimicrobials. Therefore, 59 kinds of veterinary drugs were investigated for their effects on the IgE receptor-mediated beta-hexosaminidase release from RBL-2H3 cells as an index of immediate allergic reaction. We found that the antibiotics chlorotetracycline, doxycycline, monensin, the synthetic antimicrobial pyrimethamine and the steroid hormone testosterone inhibited beta-hexosaminidase release. Most of the veterinary drugs showed no action, though the ionophores lasalocid, salinomycin and the steroid hormone hexestrol promoted beta-hexosaminidase release from injured cells. Based on the residual levels of these drugs and the frequencies of detection in actual food samples, it seems unlikely that these drugs have any immediate allergic effect in practice.     

Optical properties of end-sealed hollow fibers

We propose sealing techniques for medical hollow fibers to protect the inner surface of fibers from debris or water that scatters from targets. First, hollow fibers are sealed with a film of polymer that is easily formed by use of a dipping technique. The transmission loss of 20-microm-thick sealing film was 0.2 dB for Er:YAG laser light, and the maximum energy that is available for the film was 180 mJ. Second, a sealed glass cap was applied to the output end of hollow fiber. The silica-glass cap with a wall thickness of 400 microm shows a transmission loss of 0.5 dB and was not damaged by radiation of 400-mJ energy pulses.