Space charge distribution for various glass materials under DC stress

Space charge accumulation for various glass materials under DC stress was studied by using a pulse electroacoustic (PEA) method. We should make an acoustic matching between the sample and electron on the high‐voltage side when the hetero‐space charge distribution in glass materials is measured. The acoustic pressure wave generated from the induced charge at the high‐voltage side is canceled by the reflected one generated from hetero‐charge accumulated in the sample. Large hetero‐charge is observed in the glass materials containing MgO and CaO compound compared to the quartz glass containing no such compounds. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 148(1): 19–27, 2004; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10260     

Particle simulation of discharge current oscillation in Hall thrusters

Twenty kHz-range discharge current oscillation with a large amplitude is observed in Hall thrusters, causing unstable operation. In our previous studies, the effects of the anode orifice configuration on the current oscillation have been investigated. Using the results of neutral particle simulations, the relationship between the neutral distribution and the propellant inlet condition was analyzed. In the present study, to confirm the effect of the neutral distribution and investigate the ionization process in detail, axisymmetric analysis in the acceleration channel was carried out using a hybrid-PIC code. As a result, the periodic ionization and current oscillation were obtained. The oscillation amplitude for a smaller orifice is greater due to the higher ionization rate. The results agree with the effect of the neutral distribution predicted by the simulations.     

Probing CO on a rutile TiO2(110)surface using atomic force microscopy and Kelvin probe force microscopy

Probing CO at a specific site on a metal oxide surface is essential for characterizing various applications such as CO oxidation,hydrogenation,and water-gas shi...     

Cytocompatible and multifunctional polymeric nanoparticles for transportation of bioactive molecules into and within cells

Multifunctional polymeric nanoparticles are materials with great potential for a wide range of biomedical applications. For progression in this area of research, unfavorable interactions of these nanoparticles with proteins and cells must be avoided in biological environments, for example, through treatment of the nanoparticle surfaces. Construction of an artificial cell membrane structure based on polymers bearing the zwitterionic phosphorylcholine group can prevent biological reactions at the surface effectively. In addition, certain bioactive molecules can be immobilized on the surface of the polymer to generate enough affinity to capture target biomolecules. Furthermore, entrapment of inorganic nanoparticles inside polymeric matrices enhances the nanoparticle functionality significantly. This review summarizes the preparation and characterization of cytocompatible and multifunctional polymeric nanoparticles; it analyzes the efficiency of their fluorescence function, the nature of the artificial cell membrane structure, and their performance as in-cell devices; and finally, it evaluates both their chemical reactivity and effects in cells.     

Decomposition of a cyanine dye in binary nanosheet colloids of photocatalytically active niobate and inert clay

Binary colloids of inorganic nanosheets prepared by exfoliation of two different layered crystals form phase-separated structures with demixing of the two nanosheets. The phase-separated colloids of photocatalytic niobate and photochemically inert clay nanosheets exhibit unusual photochemical reactions based on the phase-separated structure. The present paper reports photocatalytic decomposition of a cyanine dye in this binary colloid, where the dye is selectively adsorbed on the clay nanosheets to be spatially separated from the photocatalytic nanosheets. Upon UV irradiation, the dye is photocatalytically decomposed in the colloids containing the niobate nanosheets, but self-photolysis of the dye is observed in the colloid lacking the photocatalytic nanosheets. Faster decomposition in nitrogen than in air suggests contribution of the conduction-band electrons generated in the niobate nanosheets to the photocatalytic reaction. In the binary colloid, the degradation is retarded compared with the single-component niobate colloid. Larger clay content more stabilized the dye against the decomposition. In contrast, irradiation of the colloids with visible light causes self-photolysis of the dye even in the presence of the niobate nanosheets, indicating the absence of electron transfer from the photoexcited dye to the photocatalytic nanosheets.     

FATIGUE MICROCRACKS IN A LOW CARBON STEEL

Abstract— The behaviour of a low carbon steel has been studied, in particular the initiation, growth and coalescence of fatigue microcracks on the surfaces of smooth specimens via surface replicas and photomicrographs. From the study, quantitative information on the initiation period, growth and coalescence of cracks, statistical distributions of crack length and crack depth, density of cracks, distribution pattern and characteristics of the major crack, were obtained. Knowledge of these parameters is critical for non-destructive inspection during service life and the application of fracture mechanics to life assessment.     

Efficient error estimation and adaptive meshing method for boundary element analysis

This paper describes a new and efficient error estimator by using the Direct Regular Method and h or h-r adaptive meshing for BEM analysis. This posteriori error estimator correctly indicates the discretization errors on each element. Based on the error distribution, and the adaptive meshing is generated automatically. The accuracy and convergence of this method are demonstrated by the numerical results on the stress concentration problem and the crack problem.     

Performance of thermal energy storage unit using CaCl2-NH3 system mixed with Ti

In order to develop an energy storage system using the reaction of solid CaCl₂ with ammonia gas, various properties such as volume expansion of CaCl₂ with ammoniation, activity of the chemical reaction for repeated cycles and influence of a metal additive on the heat transfer rate of the ammoniated salt were studied experimentally. The maximum volume after the reaction was 14–16 times of the ideal volume of CaCl₂. No deactivation was observed on repeated cycles. The heat transfer rate of ammoniated salts (CaCl₂ · nNH₃) was improved by adding the metal, titanium. The time required for ammoniation of CaCl₂ mixed with Ti was 10–30% shorter than for CaCl₂ alone. Similar results were obtained by repeating the cycles of ammoniation and deammoniation.     

An α2,3-Linked Sialylglycopolymer as a Multivalent Glycoligand Against Avian and Human Influenza Viruses

A glycopolymer bearing α2,3-linked sialyltrisaccharides was synthesized by living radical polymerization using a glycomonomer prepared by a protecting-group-free process, direct azidation of the free sialyllactose, and subsequent azide-alkyne cycloaddition. The prepared glycopolymer with pendant 3´-sialyllactose moieties strongly interacted with both avian and human influenza viruses analyzed by the hemagglutination inhibition assay and the quartz crystal microbalance method.