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Polyurethane- b -poly( N -isopropyl acryl amide) block copolymers having 0–40% N -isopropyl acryl amide have been synthesized via AB crosslinked polymerization technique and tested for various properties. It was possible to systematically control the thermal, mechanical, dynamic mechanical properties as well as swelling–deswelling characteristics of the copolymers by controlling the block length.

This study was to describe the findings of osteonecrosis in patients with SLE at MR and scintigraphic imaging. Among 415 patients with SLE, 37 patients were diagnosed to have osteonecrosis. MR images and bone scintigraphs were analyzed for sites of involvement, signal intensity, bilaterality and multiplicity. MR imaging features of osteonecrosis in patients with SLE included isointense signal intensity relative to adjacent bone marrow, hypointense rim, marginal enhancement and unusual involvement of flat bones. Bilateral and multiple involvements were common.

Silicon dioxide(SiO 2 ) thick films have been deposited by plasma enhanced chemical vapor deposition(PECVD) and flame hydrolysis deposition(FHD). PECVD SiO 2 films were obtained at low temperatures (

ZnO/ n -Si heterojunction solar cells were fabricated on n -Si substrates by spin coating of the ZnO precursor solution produced by the sol-gel process. In order for the ZnO films to have proper electrical conductivity, the films were doped with an n -type dopant such as aluminum, and were subsequently annealed at a temperature of 450°C under reducing environments. The ohmic contacts were formed between n -Si and Al for a bottom electrode by doping the rear surface of the Si substrate with phosphorous atoms. The front surface of the Si substrate was also doped with phosphorous atoms for improving the efficiency of the solar cells. The substrate doping was carried out with PSG (phosphosilicate glass) films produced by the sol-gel process. As a result, the conversion efficiencies of the fabricated solar cells ranging up to about 5.3% were obtained. These efficiencies were found to decrease rather quickly with time because of silicon oxide film grown at the ZnO/Si interface as a result of oxygen penetration through the porous structure of the ZnO films. Oxygen barrier layers should be needed in order to prevent the decrease of conversion efficiencies.

Thin films of zinc oxide, cadmium oxide, and their compounds have been deposited by the sol-gel process. The ZnO and CdO films are found to have different crystallographic structures and their compounds are found to be simple mixtures of the two different crystallographic strutures for the constituent materials. The electrical resistivity of the compounds, ZnxCd1−xO thin films decreases as the composition x decreases, so that pure CdO thin films have the lowest electrical resistivity of 3×10−3 Ωcm. Although the optical transmittance and bandgap of the ZnxCd1−xO films also decrease as the value of x decreases, all the films prepared in this study have a fairly high transmittance reproducibly in the visible spectral range at room temperature. The electrical resistivity of the films is found to have significant dependence on the post-deposition annealing environments. This dependence is more pronounced for the films which contain higher percentages of Zn among all the ZnxCd1−xO films prepared in this study. The dependence of the electrical resistivity on the aluminium impurity concentration in the ZnxCd1−xO films is also examined.

Hydrogenated silicon,germanium alloys, which span the transition from amorphous to polycrystalline microstructures, have been prepared by reactive magnetron sputtering from pure crystalline Si and Ge targets in a hydrogen ambient using argon as the sputtering gas. X-ray diffraction, Raman scattering, Fourier transform infrared spectroscopy, and high-resolution transmission electron microscopy have been used for microstructural characterization of films with different Ge concentrations. Microstructural changes produced by rapid thermal annealing in an Ar environment were also studied.

a-Si,N:H alloys were prepared by remote plasma-enhanced chemical-vapor deposition (PECVD), and evaluated for applications as wide band gap, photo-active materials for PV devices. These alloys have been deposited using SiH 4 as the silicon-atom source gas, and either N 2 or NH 3 as the nitrogen-atom source gas to yield films with E 04 band gaps up to ∼2.2 eV. We have characterized the microstructure, and have studied selected optical and electrical, and transport properties, comparing films prepared from N 2 and NH 3 N-atom source gases.

BACKGROUND AND PURPOSE: Injury to spinal segmental arteries may potentially occur during spinal surgery, particularly during anterior or minimally invasive approaches. Use of a noninvasive radiologic tool to evaluate these arteries before surgery may reduce this risk. MATERIAL AND METHODS: We performed spinal CT angiography and reconstructed 3D images of segmental arteries in 41 patients. We classified the pathways and locations of the segmental arteries into 4 zones (A, B, C, and D) according to pedicle and vertebral endplates. We designated segmental arteries from T8 to L1 as “high-level segmental arteries” and those from L2 to L4, as “low-level segmental arteries.” We compared the distribution of segmental arteries between these 2 groups. We also investigated anatomic variations of segmental arteries and the rate of occurrence of the artery of Adamkiewicz. RESULTS: In all patients, 3D reconstruction images from spinal CT angiography clearly showed the pathways of segmental arteries on the vertebral bodies. Most of the segmental arteries passed the middle portion of the vertebral body (zones B and C). However, 51 of 738 segmental arteries (6.9%) had uncommon pathways (zones A and D), and segmental arteries from L2 to L4 had a higher incidence of uncommon pathways than higher level vertebrae (P < .05). We also observed 2 types of segmental artery anatomic variation, agenesis and dual supply. CONCLUSIONS: We suggest that spinal CT angiography can help to precisely visualize the spinal segmental arteries and surrounding bony structures and can aid clinicians in deciding on optimal approaches for spinal surgery.

Summary Objective: Questionnaire-based ADHD screening tests may not always be objective or accurate, owing to both subjectivity and prejudice. Despite attempts to develop objective measures to characterize ADHD, no widely applicable index currently exists. The principal aim of this study was to develop a decision support model for ADHD screening by monitoring children’s school activities using a 3-axial actigraph. Methods: Actigraphs were placed on the non-dominant wrists of 153 children for 3 hours, while they were at school. Children who scored high on the questionnaires were clinically examined by child psychiatrists, who then confirmed ADHD. Mean, variance, and ratios of low-level (0.5-1.0G) and high-level (1.6-3.2G) activity were extracted as activity features from 142 children (10 ADHD, 132 non-ADHD). Two decision-tree models were constructed using the C5.0 algorithm: [A] from whole hours (class + playtime) and [B] during classes. Accuracy, sensitivity, and specificity were evaluated. PPV, NPV, likelihood ratio, and AUC were also calculated for evaluation. Results: [Model A] One child without ADHD was misclassified, resulting in an accuracy score of 99.30%. Sensitivity and NPV were 1.0000. Specificity and PPV were 0.992 and 0.803-0.909, respectively. [Model B] Two children without ADHD were misclassified, resulting in an accuracy score of 98.59%. Specificity and PPV were scored at 0.985 and 0.671-0.832, respectively. Conclusion: The selected features were consistent with the findings of previous studies. Objective screening of latent patients with ADHD can be accomplished with a simple watch-like sensor, which is worn for just a few hours while the child attends school. The model proposed herein can be applied to a great many children without heavy cost in time and manpower cost, and would generate valuable results from a public health perspective.

We present ASDSP (application-specific digital signal processor) instructions and their hardware architecture for high-speed FFT. The proposed instructions calculate a butterfly within two cycles. The proposed architecture employs a data processing unit (DPU) supporting the instructions and an FFT address generation unit (FAGU) automatically calculating the butterfly input and output data addresses. The proposed DPU has a smaller area than commercial DSP chips. Moreover, the number of FFT computation cycles is reduced by the proposed FAGU. The architecture has been modeled by the VHDL. We have used the UMC 0.25/spl square/standard cell library for logic synthesis. Performance comparisons show that the number of execution cycles is reduced over 10% and the size of the DPU decreases about 30% compared with Carmel DSP.

This paper proposes a high speed OFDM modem architecture for powerline communications. The proposed modem using symmetric communication is designed to be compatible with the HomePlug standard. The HomePlug standard adopts from DC to 25 MHz frequency bandwidth, 128 subcarriers for OFDM transmission, and BPSK, DBPSK, and DQPSK modulations for each subcarrier. In particular, this paper proposes algorithms and the associated architectures for the signal detection, AGC and frame synchronization. The AGC and frame synchronization algorithms are based on the symbol power ratio and the sliding cross-correlation of preamble, respectively. The frame is then synchronized with a position of the minimum correlation value. In addition, an area-efficient integrate-and-dump architecture for frame synchronization is proposed. The proposed architectures have been validated using SPW/spl trade/ and implemented with Verilog-XL. We show that the BER performance of the proposed modem under an AWGN channel is similar to the theoretical one.

A working methodology bypasses the conventional cell plate line (PL), mitigating its disadvantages. The methodology utilizes split word lines (SWLs), driven by multi-phased voltage signals. In this scheme there is no need for PL and additional elements, and fabrication is simple and compatible with downscaling of cell area.

This paper reports the results of a parallel computation of a transonic flow past a 3D wing using the Hanbit-1 computer, a hypercube parallel computer developed at KAIST (Korea Advanced Institute of Science and Technology). Two different numerical schemes, one a lower-upper symmetric Gauss-Seidel (LU-SGS) method and the other a Runge-Kutta time-stepping scheme, were used. The performance of the Hanbit-1 was assessed based on the present parallel computation with domain decomposition.

We have investigated on the effect of different substrate surfaces in changing the microstructure of μc-SixGe1-x:H films prepared by reactive magnetron sputtering. Films were deposited on hydrogen terminated Si(111), Si(100) surfaces, and surfaces chemical and plasma oxides. The thin film microstructure was characterized by Fourier transform infrared spectroscopy (FTIR), high resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), and Raman scattering.

Amorphous and microcrystalline silicon-germanium alloys, a-SixGel-x:H and μc-SixGel-x:H, respectively, have been prepared by reactive magnetron sputtering (RMS) from pure crystalline Si and Ge targets in a hydrogen ambient using argon as the sputtering gas. We have investigated the structural, optical, and electronic properties of the as-deposited films. The optical and electrical properties, e.g., the ambipolar diffusion length, photoconductivity, and photosensitivity, were found to be comparable to those of device-grade a-SixGe1-x:H alloys, e.g., films with x ∼ 0.5, and band-gaps ∼ 1.3–1.4 eV. In contrast to the behavior of the a-SixGel-x:H alloys, the μc-SixGe1-x:H alloys do not display a Staebler-Wronski effect, as manifested by a decay of the photoconductivity under intense illumination.

Many photoelectronic properties of a-Si,N:H alloys prepared by remote PECVD (RPECVD) from two N-atom source gases - N2 and NH3 - are the same; however, the photo-induced changes in the electrical properties in alloys with -2.1 eV bandgaps are ∼3 to 5 times greater in alloys deposited from NH3, which display Si-NH, as well as SiH bonding. Based on this result, we show that bonding groups important in the Staebler-Wronski effect include (i) ≡SiH, and nearest-neighbor (ii) ≡Si-NH-Sis and/or ≡Si-O-Sis in which the respective N and O-atoms make H-bonds with the sSiH group. The model, based on ab-initio calculations, includes a H-exchange reaction in which trapping of photo-generated holes promotes a transfer of the H-atom from the ^SiH group to a nearest-neighbor ≡Si-NH-Si≡ creating (i) a Si-dangling bond (Si*) and (ii) a Metastable (≡Si-NH2-Si≡) + group. Calculations indicate that neutral (≡Si-NH2≡Sis) ° is unstable, so that relaxation of (≡Si-NH2-Si≡) + groups can occur by trapping of a thermally-released (trapped) electron during a post-light-soaking thermal-anneal. The same type of model is developed for hole/electron trapping-induced H-atom transfer between ≡SiH and ≡Si-0-Si≡ groups in other a-Si:H Materials.

We have compared the photo-transport properties of thin films of B-compensated Μc-Si and device-grade a-Si:H prepared by remote plasma-enhanced chemical-vapor deposition (PECVD). The steady state photocarrier grating technique was used to determine the ambipolar diffusion lengths, Lamb. The conductivity of the μc-Si:B thin films changed from n-type to p-type as the B2H6 fraction in the B2H6/SiH4 source gas mixture was increased. The steady state photoconductivity, σph, decreased as B2H6 was initially introduced and the material changed from n-type to intrinsic; σph then increased as the material converted to p-type. Lamb displayed a complementary behavior with a maximum value at the approximate compensation point between the n-type and p-type conductivity regions. The steady-state photoconductivity and Lamb did not show any significant photo-induced degradations under intense illumination. Finally, the photoconductivity and Lamb displayed a strong dependence on sample thickness which is associated with Fermi level pinning at the surface.

We have deposited films of a-Si,N:H by remote PECVD from N2 and SiH4 for N-concentrations, [N], to about 12 atomic percent (at. %). Bonded-H concentrations were ∼7–10 at. %, Mostly in Si-H groups. The films with [N] = 9–12 at. % have εθ4 bandgaps of ∼2.0 to 2.2 eV, which makes them potentially useful as wide bandgap photo-active materials in tandem PV cells. Several properties are of special interest for PV applications. First, like many other a-Si:H-based alloys, the photoconductivity relative to a-Si:H is degraded by alloying, but less than for a-Si,C:H alloys with the same bandgaps. Second, the ambipolar diffusion lengths (Ld) obtained with the Steady State Photocarrier Grating (SSPG) technique for films with [N] = 10 at. % and εθ4 = 2.1eV, are comparable to those of a-Si:H. For lightly-nitrided films to [N] ∼5 at. %, Ld first decreases with respect to a-Si:H and then increases as [N] increases from ∼7 at.% to 10–12 at. %. These trends follow the dark conductivity activation energy, Ea, which initially drops due to doping, and then increases into an alloy regime for [N] > 5 at. %. Films with [N1=10 at. % have dark conductivities and Ea's comparable to those of undoped a-Si:H. Third the magnitude of the Staebler-Wronski effect, as monitored by the photo- to dark conductivity ratio after a 1000 Minute lightsoak, was about the same as in a-Si:H. Finally, we contrast the properties of these films prepared from N2 with a-Si,N:H alloys with the same [N] and E04, but prepared from an ammonia N-atom source gas and attribute differences in their photoelectronic behavior such as a significantly enhanced Staebler-Wronski effect.to the presence of Si-NH bonding arrangements in the films grown from NH3.

SixGei1−x:H alloys which span the transition from amorphous to microcrystalline structures have been prepared by reactive magnetron sputtering (RMS) from pure crystalline Si and Ge targets in different partial pressures of hydrogen, using argon as the sputtering gas. Film properties were studied as a function of H2 flow and partial pressure. X-ray diffraction (XRD), Raman scattering, Fourier transform infrared spectroscopy (FTIR), reflection high-energy electron diffraction (RHEED), and high resolution transmission electron microscopy (HRTEM) have been used for microstructural characterization. Films prepared by RMS at a partial pressure of hydrogen (PH2) < ∼ 4 mTorr were amorphous, while those prepared with PH2 > ∼ 6 mTorr were microcrystalline.

We have incorporated N-atoms into hydrogenated amorphous silicon in the Si-rich alloy regime to ∼12 at.% N, and have observed a transition from n-type doping to alloying as the concentration of N-atoms is increased above about 5 at.%. By analogy with the local bonding arrangements of P-donors in n-doped a-Si:H, we attribute the doping to four-fold coordinated N-atoms with second neighbor H-atoms as in N+-Si-H linkages. The occurrence of these arrangements is supported by (i) IR studies which indicate a non-statistical association of N and H-atoms bonded to the same Si-atom, and (ii) a chemical bonding model in which the large effective electronegativies of four-fold coordinated N+ atoms and neutral O-atoms promote similar bonding properties with respect to their nearest-neighbor arrangements with Si and H atoms such as N+ (O) -Si-H linkages

We have investigated a-Si,N:H alloys as an alternative wide band-gap, photo-active material. The entire alloy range between a-Si:H and a-Si3N4:H can be formed by a remote plasma-enhanced chemical-vapor deposition (PECVD) process. Other studies have demonstrated that a-Si,N:H alloys could be doped to form window materials for p-i-n devices. This paper focuses on alloy materials with E04 bandgaps to about 2.2 eV. We have prepared these a-Si,N:H alloys, characterized their microstructure, and studied their photoconductivity, sensitivity to light-soaking and transport properties. For example, with increased alloying we show that i) the white-light photoconductivity and ii) the kinetics and magnitude of the decay of photoconducitivity under intense illumination (the Staebler-Wronski effect), are about the same as for PV-grade a-Si:H.

We have investigated the difference in the electronic energies of neutral Si and Ge dangling bond states in undoped a-Si1-xGex alloys as a function of the alloy composition, x, and local bond-angle distortions. The local density of states, LDOS, in a-Si1-xGex alloys has been calculated using nearest-neighbor interactions, and employing the Cluster Bethe Lattice method. We conclude that for ideal, tetrahedrally bonded amorphous semiconductors alloys, the Ge dangling bond energy is lower than that of Si dangling bonds by ∼ 0.13 eV, independent of the specific nearest neighbors to the dangling bond (3 Si-atoms, 2 Si-atoms and 1 Ge-atom, etc.), but that the spread in dangling bond energies associated bond-angle variations of the order of 6–8 degrees can be larger than this energy difference (∼0.3 eV or greater). This means that structural disorder, rather than chemical disorder causes Si and Ge-atom dangling bond states to overlap in their energy distributions.

The feasibility of thermal transient testing of sodium components using a fluid other than sodium is considered. Simulation of thermal transient conditions that may exist in the sodium system is considered to be, in general, achievable in a special test fixture, if the thermal and hydraulic conditions of the fluid to be used are properly selected. This feasibility is demonstrated for the 28 in. FFTF hot-leg isolation valve by introducing a high-speed gaseous nitrogen flow into an annulus formed by the valve body and a cylindrical pipe insert. The structural wall temperature distributions were estimated first for the sodium system, and the simulation was established by equating the transient heat transfer rates as a function of time at key locations in both real sodium and simulating nitrogen systems. Remarkably good simulation test results were achieved.

Analytical models are presented for the determination of thermal field in the heat transfer tubing under critical heat flux (CHF)-induced thermal oscillations in a sodium-heated steam generator. The oscillatory nature of the water/steam convective boundary conditions in the post-CHF transition boiling is simulated by postulating a number of rivulet-type wet regions that are swirled around the tube circumference. The rate at which the rivulets are swirled or rotated is determined by the indications of recent test data at Argonne National Laboratory. The same test data are also used as the criteria on model development. The results of 1-, 2- and 3-dim. models indicate that the 2-dim. (radial-circumferential) model with three or four rivulets and a 26.7% total circumferential wetness may be adequate for the thermal analysis of heat transfer tubing under oscillatory transition boiling.

A 30-Mwt prototype sodium-to-sodium intermediate heat exchanger and a 30-Mwt prototype sodium-heated steam generator were tested in combined operation in its Sodium Components Test Installation. This report contains the results of test and evaluation of the steam generator. During plant performance tests, performance degradation was observed, which resulted in the initiation of a diagnostic test series. This test series revealed that under certain operating conditions, the thermohydraulic characteristic of the steam generator changed either suddenly or gradually, resulting in overall performance degradation. A structural failure, requiring retirement of the unit, occurred before the diagnostic test series and analytical support effort were completed. This report describes the thermohydraulic and structural performance, including the structural failures, and related evaluation analyses of the Alco/BLH prototype steam generator performed prior to termination of the test and evaluation program. In addition, the report presents a post-test examination plan to obtain data that could possibly explain the cause of performance anomalies and structural failures experienced during testing.

A new type diffractive spatial optical modulator has been developed for laser projection display. It has inherent advantages such as fast response time and high-performance light modulation characteristics. Also, it is suitable for embedded mobile projection display module because of its compact optical volume (les 20 cc) and low power consumption (les 2.0 W).