脉冲或连续X射线预电离气体激光器

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Synthesis and properties of superabsorbent hydrogels based on guar gum and succinic anhydride

Synthesis of novel superabsorbent hydrogels has been investigated with the reaction of guar gum and succinic anhydride (SA), using of 4‐dimethylaminopyridine as esterification promoter and water or dimethylsulfoxide (DMSO) as reaction solvent, followed by NaOH neutralization. Hydrogels prepared in water exhibited somewhat higher water absorbency than those prepared in DMSO; its maximum water absorbency in pure water and aqueous 0.9% NaCl solution was ca. 200 g/g and 80 g/g, respectively. These values were considerably higher than those of hydrogels obtained from starch in a similar way. The products in this study biologically degraded up to 70–80% after 10 days in activated sludge, which shows their excellent biodegradability. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Oncocytic hepatocellular carcinoma with numerous globular hyaline bodies

The current approach to the management of physician resources in Canada needs to be re-examined by all concerned. Canada is about to enter a phase of accelerating depletion of physicians as the result of two separate and evolving circumstances. Because of the unusually large number of physicians who graduated from Canadian medical schools in the late 1960s and early 1970s, a significantly larger than usual number of practising physicians will reach their normal retirement age in the decade ahead. In addition, if the recent surge in the emigration of Canadian physicians continues, the loss of so many physicians will exaggerate the impact of the expected increase in retirements. Therefore, the decision to cut medical school class sizes in the 1990s would have been more suitable in the early 1980s. Existing physician work force policies may be leading to unexpected or undeclared consequences for health care across Canada. On the basis of current trends, the author concludes that policy makers now should reconsider current physician workforce policies in anticipation of a possible shortfall of physicians beginning in the early decades of the next century.     

Relationship between response to interferon therapy and detection of hepatitis C virus RNA by differential flotation centrifugation

Problem-based learning (PBL) is a method of instruction gaining increased attention and implementation in medical education. In PBL there is increased emphasis on the development of problem-solving skills, small group dynamics, and self-directed methods of education. A weekly PBL conference was started by a university consultation psychiatry team. One active consultation service problem was identified each week for study. Multiple computerized and library resources provided access to additional information for problem solving. After 1 year of the PBL conference, an evaluation was performed to determine the effectiveness of this approach. We reviewed the content of problems identified, and conducted a survey of conference participants. The most common types of problem categories identified for the conference were pharmacology of psychiatric and medical drugs (28%), mental status effects of medical illnesses (28%), consultation psychiatry process issues (20%), and diagnostic issues (13%). Computerized literature searches provided significant assistance for some problems and less for other problems. The PBL conference was ranked the highest of all the psychiatry resident educational formats. PBL appears to be a successful method for assisting in patient management and in resident and medical student psychiatry education.     

Binaural Localization Based on Weighted Wiener Gain Improved by Incremental Source Attenuation

This paper addresses the problem of direction-of-arrival (DOA) estimation both in azimuthal and elevation angle from binaural sound that is processed with a head-related transfer function (HRTF). Previously, we proposed a weighted Wiener gain (WWG) method for two-dimensional DOA estimation with two-directional microphones. However, for signals processed with HRTFs, peaks in the spatial spectra of WWG indicating true sources can mingle with spurious peaks. To resolve this situation, we propose to apply incremental source attenuation (ISA) in combination with WWG. In fact, ISA reduces spectral components originating from specified sound sources and thereby improves the localization accuracy of the next targeted source in the proposed incremental estimation procedure. We conduct computer simulations using directional microphones and four HRTF sets corresponding to four individuals. The proposed method is compared to two DOA estimation methods that are equivalent to two generalized cross-correlation functions and two high-resolution methods of multiple signal classification (MUSIC) and minimum variance method. For comparison purposes, we introduce binary coherence detection (BCD) to high-resolution methods for emphasizing valid spectral components for localization in multiple source conditions. Evaluation results demonstrate that, although MUSIC with BCD yield comparable performance to that of WWG in conditions where single speech source exists, WWG with ISA surpasses the other methods in conditions including two or three speech sources.     

Pre-evaluation method for the spectroscopic properties of YAG bulk materials by sol–gel synthetic YAG powder

We propose a convenient method for pre-evaluating the spectroscopic properties of luminescent impurity doped YAG by sol–gel synthetic powder. Three synthetic methods, the sol–gel, normal-strike, and reverse-strike methods, are examined for their ability as a predictor and the sol–gel method proved the most effective of the three in experiments on crystallinity, particle size, and spectroscopic properties. The sol–gel Nd:YAG powder agrees well with that of a single crystal or ceramic YAG regarding the luminescent spectrum, the intensity, and the lifetime, even though the powder sintered at a low temperature of 1100 °C in comparison with the YAG crystal melting point of 1970 °C. These facts suggest that the sol–gel synthetic powder is the most effective and the easiest technique for evaluating spectroscopic properties of bulk YAG materials before fabricating the final materials.     

Hardenability Improvement Mechanisms and Hardenability-Controlling Factors in Steels With Combined Mo–B Addition

Metallurgical and Materials Transactions A - To elucidate the hardenability improvement mechanisms and hardenability-controlling factors in low-carbon (C) steels with the combined addition of...     

Cell-Based in Vitro Blood–Brain Barrier Model Can Rapidly Evaluate Nanoparticles’ Brain Permeability in Association with Particle Size and Surface Modification

The possibility of nanoparticle (NP) uptake to the human central nervous system is a major concern. Recent reports showed that in animal models, nanoparticles (NPs) passed through the blood–brain barrier (BBB). For the safe use of NPs, it is imperative to evaluate the permeability of NPs through the BBB. Here we used a commercially available in vitro BBB model to evaluate the permeability of NPs for a rapid, easy and reproducible assay. The model is reconstructed by culturing both primary rat brain endothelial cells and pericytes to support the tight junctions of endothelial cells. We used the permeability coefficient (P_app) to determine the permeability of NPs. The size dependency results, using fluorescent silica NPs (30, 100, and 400 nm), revealed that the P_app for the 30 nm NPs was higher than those of the larger silica. The surface charge dependency results using Qdots^® (amino-, carboxyl-, and PEGylated-Qdots), showed that more amino-Qdots passed through the model than the other Qdots. Usage of serum-containing buffer in the model resulted in an overall reduction of permeability. In conclusion, although additional developments are desired to elucidate the NPs transportation, we showed that the BBB model could be useful as a tool to test the permeability of nanoparticles.     

Spectroscopic comparison between 1200 grooves/mm ruled and holographic gratings of a flat-field spectrometer and its absolute sensitivity calibration using bremsstrahlung continuum

A flat-field extreme ultraviolet (EUV) spectrometer with a varied line spacing groove grating (1200 grooves/mm at grating center) has been developed to study the emission spectra from highly ionized medium Z impurities in large helical device (LHD). It covers a wavelength range of 50-500 A using a mechanically ruled grating, which was later replaced by a newly developed laminar-type holographic grating for comparative studies. Differences in spectral resolution, intensities of higher order spectra, and sensitivities of the spectrometer were studied between the two gratings by observing the emission spectra of LHD plasmas. Although the achieved resolution was alike between them, i.e., deltalambda approximately 0.24 A at 200 A, the holographic grating was much superior in suppressing the higher order light than the ruled grating. The relative sensitivity between the two gratings was evaluated using continuum radiation from LHD plasmas. As a result, it was found that the holographic grating has a flat response in the full wavelength range, but the sensitivity of the ruled grating drops sharply below 200 A. A new technique for the absolute calibration of the EUV holographic grating spectrometer was tried by combining the continuum radiation with a branching ratio of C IV lines (3p-3s: 5800 A/3p-2s: 312 A), and an accurate absolute sensitivity has been successfully obtained.     

Fabrication of oxide-gate thin-film transistors using PECVD/PLD multichamber system

We developed a new multichamber system which combines a pulsed-laser deposition (PLD) and a plasma-enhanced chemical vapor deposition (PECVD) with shadow masks installed to define the film deposition area on a substrate. In order to verify thecapability of this PLD/PECVD multichamber system, hydrogenated amorphous silicon (a-Si:H) thin film transistors (TFTs) using MgO and Al2O₃ gate dielectrics have been fabricated on glass/indium-tin-oxide (ITO) substrates. The MgO and Al2O₃ films fabricated on fused silica substrates by PLD exhibited transparency higher than 90% and a low leakage current (1 nA/cm² at 1 MV/cm). After depositions of the MgO or Al2O₃ film on the glass/ITO, thesample was transferred to the PECVD chamber for a-Si:H deposition without exposing them to the air. TFTs thus fabricated exhibited such high characteristics as the threshold voltage (VTH) as low as 0.35 V and gate bias dependence of source±drain current exceeding five orders of magnitude. Theresults indicate a high quality a-Si:H/oxide interface and that heterojunction devices can be produced by using the PLD/PECVD multichamber system.