Formation mechanisms of paramagnetic defect centers induced by excimer lasers,gamma rays,and mechanical fracturing in amorphous SiO2

The formation mechanisms of paramagnetic defect centers in amorphous SiO₂ induced by excimer lasers, ⁶⁰Co γ rays, and mechanical fracturing were investigated. Correlation between the paramagnetic defect centers and their precursors introduced during manufacture is discussed for the cases of excimer lasers and γ rays. For the case of mechanical fracturing, formation of strained Si·O·Si bonds as well as paramagnetic defects is examined. The mechanism of laser- or γ-ray-induced paramagnetic defect centers is compared with that of fracture-induced centers. © 1998 Scripta Technica, Inc. Electr Erg Jpn, 121(3): 9–19, 1997     

Cytokine Networks in the Pathogenesis of Rheumatoid Arthritis

Rheumatoid arthritis (RA) is an autoimmune disease characterized by chronic systemic inflammation causing progressive joint damage that can lead to lifelong disability. The pathogenesis of RA involves a complex network of various cytokines and cells that trigger synovial cell proliferation and cause damage to both cartilage and bone. Involvement of the cytokines tumor necrosis factor (TNF)-α and interleukin (IL)-6 is central to the pathogenesis of RA, but recent research has revealed that other cytokines such as IL-7, IL-17, IL-21, IL-23, granulocyte macrophage colony-stimulating factor (GM-CSF), IL-1β, IL-18, IL-33, and IL-2 also play a role. Clarification of RA pathology has led to the development of therapeutic agents such as biological disease-modifying anti-rheumatic drugs (DMARDs) and Janus kinase (JAK) inhibitors, and further details of the immunological background to RA are emerging. This review covers existing knowledge regarding the roles of cytokines, related immune cells and the immune system in RA, manipulation of which may offer the potential for even safer and more effective treatments in the future.     

Steam absorption process of water/LiBr system inside vertical small bore pipes

In a previous paper, a numerical model for absorption within vertical pipes was proposed and compared with the experiments. Agreements were good for pipes with an OD 28–15 mm but at 10 mm pipe experiments fell below the predicted values. For smaller diameters, the difference between the surface area of the falling liquid film and that of the outer surface of the pipe is not negligible and the thickness of the liquid film is also not negligible. In this paper a new model is formulated in cylindrical coordinates and experiments using pipes with 9.52 mm and 7 mm OD are done. Smooth pipes and two kinds of internally finned pipes, originally developed and used to enhance the heat transfer characteristics of the evaporator and condenser of a refrigerator using HFC as refrigerant, are tested in the experiments. The absorption performance is enhanced by 30% when compared to the smooth pipes, but the difference between the finned pipes is small. © 2004 Wiley Periodicals, Inc. Heat Trans Asian Res, 34(1): 18–28, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.20040     

Non-contact atomic force microscopy study of atomic manipulation on an insulator surface by nanoindentation

Experimental results on vertical manipulation on an insulator surface using non-contact atomic force microscopy are presented. Cleaved ionic KCl(100) single crystal is used as an insulator surface. With the nanoindentation method used, the vertical manipulation of a single atom in an ionic crystal surface is more difficult than in a semiconductor surface. Therefore, in many cases, more than one surface atom is manipulated while, in rare cases, single-atom manipulation is successfully performed. Lateral manipulation of a vacancy has occasionally succeeded on the KCl(100) surface. We have presumed that the lateral manipulation was induced by pulling.     

Fabrication of barium titanate nanoparticles‐epoxy resin composite films and their dielectric properties

A method for fabricating epoxy resin films dispersing the surface‐modified barium titanate (BT) particles (BT‐epoxy resin composite films) are proposed. BT particles with a size of 7.8 nm and a crystal size of 8.6 nm were synthesized with a complex alkoxide method. To introduce epoxy groups on the BT particle surface, the BT particles were surface‐modified with 2‐(3,4‐epoxycyclohexyl)‐ethyltrimethoxysilane. A precursor solution, which was prepared by prereacting 2,2‐bis(4‐glycidyloxyphenyl)propane (BGPP) and phthalic anhydride in 4‐butyrolactone and adding the surface‐modified BT particles to the prereacting solution, was spin‐coated on glass substrates to fabricate the composite films. An increase in BT volume fraction in film increased dielectric constant of the composite film while keeping dissipation factor below 0.03. The dielectric constant attained 10.8 at a BT volume fraction of 30% in film that was around twice higher than pure epoxy resin film. POLYM. COMPOS., 31:1179–1183, 2010. © 2009 Society of Plastics Engineers     

Variations in signal intensity with periodical temperature changes in vivo in rat brain: analysis using wide-field optical coherence tomography

In a previous study, we reported measurements of three-dimensional (3D) optical coherence tomography (OCT) images through a thinned skull by reducing temperatures from 28 °C to 18 °C in vivo in the rat brain to show negative correlation coefficients (CCs) between ratios of signal intensity (RSI) and temperature for applications to monitoring brain viability. In this study, using the same OCT system, we measured 3D OCT images of the rat brain by periodically changing tissue temperatures from 20 °C to 32 °C in vivo. In the evaluation of CCs among RSI, temperature, and heart rate, the largest number of periods was four, and the longest measurement time was 570 min. Averaged CCs between RSI and temperature, and between RSI and heart rate, were -0.42 to -0.50 and -0.48 to -0.64, respectively. RSI reversibly changed subsequent variations of temperatures and finally increased rapidly just before cardiac arrest. These results indicate that RSI could correspond to decreases in viability because of local ischemia and recovery.     

High quality epitaxial ZnO films grown on solid-phase crystallized buffer layers

High quality epitaxial ZnO films on sapphire (110) plane have been fabricated on ZnO homo-buffer layers crystallized via solid-phase epitaxially (SPE). The SPE-ZnO films are fabricated by annealing of amorphous ZnON (a-ZnON) films deposited by RF magnetron sputtering. During annealing, the a-ZnON films are oxidized and converted to ZnO crystal. X-ray diffraction (XRD) analysis shows that the resultant films are epitaxially grown on the sapphire substrates. By using the SPE-ZnO films as homo-buffer layers, the ZnO films with high crystallinity, which are deposited by RF magnetron sputtering, are fabricated. The full width at half-maximum of XRD patterns for 2θ-ω and ω scan of (002) plane are 0.094° and 0.12°, respectively, being significantly small compared with 0.24° and 0.55° for the films without buffer layers. Thus utilizing SPE buffer layers is very promising to obtain epitaxial ZnO films with high crystallinity.     

Development of an energy-binned photon-counting detector for X-ray and gamma-ray imaging

The aim of this study is to develop an energy-binned photon-counting (EBPC) detector that enables us to provide energy information of x-rays with a reasonable count statistics. We used Al-pixel/CdTe/Pt semiconductor detectors, which had an active area of 8 mm×144 mm and consisted of 18 modules aligned linearly. The size of a CdTe detector module was 8 mm×8 mm and the thickness of the CdTe crystal was 1 mm. Each module consisted of 40×40 pixels and the pixel size was 200 μm×200 μm. We applied the bias voltage of −500 V to the Pt common electrode. The detector counted the number of x-ray photons with four different energy windows, and output four energy-binned images with pixel depths of 12, 12, 11 and 10 bits at a frame rate of 1200 Hz (300 Hz×4 energy bins). The basic performance of the detector was evaluated in several experiments. The results showed that the detector realized the photon counting rate of 0.4×10⁶ counts/sec/pixel (10⁷ counts/sec/mm²), energy resolution 4.4% FWHM at 122 keV. The integral uniformity of the detector was about 1% and the differential uniformity was about 1%. In addition, the image quality was examined with a resolution chart and step-wedge phantoms made of aluminum and polymethyl methacrylate. And we compared the quality of an acquired image with that acquired with an energy integration detector. The results of these experiments showed that the developed detector had desirable intrinsic characteristics for x-ray photon counting imaging.     

Crystal growth and scintillation properties of Er-doped Lu3Al5O12 single crystals

Er-doped Lu₃Al₅O₁₂ (Er:LuAG) single crystalline scintillators with different Er concentrations of 0.1, 0.5, 1, and 3% were grown by the micro-pulling-down (μ-PD) method. The grown crystals were composed of single-phase material, as demonstrated by powder X-ray diffraction (XRD). The radioluminescence spectra measured under ²⁴¹Am α-ray excitation indicated host emission at approximately 350 nm and Er³⁺ 4f-4f emissions. According to the pulse height spectra recorded under γ-ray irradiation, the 0.5% Er:LuAG exhibited the highest peak channel among the samples. The γ-ray excited decay time profiles were well fitted by the two-component exponential approximation (0.8 μs and 6-10 μs).