Search

BACKGROUND AND PURPOSE: Temporal lobe epilepsy is the most common type of epilepsy. Early surgical treatment is superior to prolonged medical therapy in refractory temporal lobe epilepsy. Successful surgical operations depend on the correct localization of the epileptogenic zone. This study aimed to evaluate the clinical value of hybrid TOF-PET/MR imaging–based multiparametric imaging in localizing the epileptogenic zone in patients with MR imaging-negative for temporal lobe epilepsy. MATERIALS AND METHODS: Twenty patients with MR imaging-negative temporal lobe epilepsy who underwent preoperative evaluation and 10 healthy controls were scanned using PET/MR imaging with simultaneous acquisition of PET and arterial spin-labeling. On the basis of the standardized uptake value and cerebral blood flow, receiver operating characteristic analysis and a logistic regression model were used to evaluate the predictive value for the localization. Statistical analyses were performed using statistical parametric mapping. The values of the standardized uptake value and cerebral blood flow, as well as the asymmetries of metabolism and perfusion, were compared between the 2 groups. Histopathologic findings were used as the criterion standard. RESULTS: Complete concordance was noted in lateralization and localization among the PET, arterial spin-labeling, and histopathologic findings in 12/20 patients based on visual assessment. Concordance with histopathologic findings was also obtained for the remaining 8 patients based on the complementary PET and arterial spin-labeling information. Receiver operating characteristic analysis showed that the sensitivity and specificity of PET, arterial spin-labeling, and combined PET and arterial spin-labeling were 100% and 81.8%, 83.3% and 54.5%, and 100% and 90.9%, respectively. When we compared the metabolic abnormalities in patients with those in healthy controls, hypometabolism was detected in the middle temporal gyrus (P < .001). Metabolism and perfusion asymmetries were also located in the temporal lobe (P < .001). CONCLUSIONS: PET/MR imaging–based multiparametric imaging involving arterial spin-labeling may increase the clinical value of localizing the epileptogenic zone by providing concordant and complementary information in patients with MR imaging-negative temporal lobe epilepsy.

In this paper, a novel rasorber with both Frequency Selective Surface and absorptive periodical structure is developed. This rasorber works as a radome and an absorber. Firstly, the design procedure of the unit cell of this rasorber is explained. Then, the characteristics of the manufactured rasorber are measured. The characteristics include the transmission/reflection coefficients of the rasorber, the radiation properties of the horn antenna covered by the novel rasorber and the scattering features of this rasorber. In the passband, the gain of the antenna with our rasorber radome is only 1~2 dB lower than the one of the horn antenna without any radome. Furthermore, the radome has little effect on the radiation patterns of the horn antenna. In the absorptive bands of the rasorber, the electric level of the scattered electromagnetic wave from the rasorber can be 16.5 dB lower than the one from a metallic plane with the same size as the rasorber. The feature proves that this rasorber can be a good candidate in the stealth radar radome area.

Detecting the land cover changes is an important application of multi-temporal synthetic aperture radar (SAR) images. This study puts forward a novel SAR change detection method which has two-steps: change detector construction and change threshold selection. For change detector construction, considering the SAR intensity images follow the gamma distribution, the conditional probabilities of the binary hypothesis test are provided, then the log likelihood ratio (LLR) combined with the log ratio (LR) to construct a detector which can enhance the degree of change to calculate the diversity degree convenient between the two images; for change threshold selection, owing to the characteristic that the curve about the ratio value of adjacent grey-level (GL) values in normalized difference map, the normalized difference map can be segmented in three parts by two thresholds selected which correspond to the regions of unchanged, backscatter enhanced and weakened separately. And as this, the change areas can be also determined simultaneously. The experimental results on different areas and sensors indicate that the proposed algorithm is effective and feasible.

Information on the structural evolution of materials under high pressure is of great importance for understanding the properties of materials exhibited under high pressure. High-pressure powder diffraction is widely used to investigate the structure evolution of materials at such pressure. Unfortunately, powder diffraction data are usually insufficient for retrieving the atomic structures, with high-pressure single-crystal diffraction being more desirable for such a purpose. Here, a high-pressure single-crystal diffraction experimental system developed recently at beamline 4W2 of Beijing Synchrotron Radiation Facility (BSRF) is reported. The design and operation of this system are described with emphasis on special measures taken to allow for the special circumstance of high-pressure single-crystal diffraction. As an illustration, a series of diffraction datasets were collected on a single crystal of LaB6 using this system under various pressures (from ambient pressure to 39.1 GPa). The quality of the datasets was found to be sufficient for structure solution and subsequent refinement.

The technology of arranging particles by ultrasound has matured. In recent years, this technology has been used as a basis for arranging particles in a photocurable resin for stereolithography (SL). In order to process the resin doped with particles to obtain a variety of particle arrangement patterns, most of the previous work chose to use different polygonal containers to obtain single-layer fiber angles. In this adjustment mode, the selectivity of the fiber angle is very poor, usually 45°, 90° and other common angles. In this work, we designed and manufactured a new ultrasound-assisted 3D printing platform that can flexibly adjust the thickness of the sandwich and the rotation angle of the sandwich. We will introduce the basic working principle and matching usage of the device, and show some basic print samples.

Synopsis Through indirectly heating a TAC foam with ns laser driven gold hohlraum radiation, isolated, highly homogeneous and long-living dense ionized matter was generated in laboratory. This provide a fantastic sample for investigation of dense plasma science and technology. The emission spectra of the plasma with time, spatial and spectral resolution were measured with various techniques. The temperature and electron density are precisely diagnosed on the basis of the spectra.

Background T helper 17 (Th17) cells play a central role in rheumatoid arthritis(RA) via the production of pro-inflammatory cytokines interleukin (IL)−17. SWAP-70- like adapter of T cells (SLAT) has recently emerged as an important regulator of Th17 differentiation. Aptamer-facilitated cell specific delivery of shRNA represents an attractive novel approach for efficient RNAi delivery. However, the role of CD30 aptamer-SLAT-shRNA chimaeras in regulating Th17 differentiation in patients with RA is unclear. Objectives SLAT play a crucial role in regulating Th17 cell differentiation and function. This study was undertaken to investigate the role and mechanism of SLAT in Th17 cells differentiation in patients with RA. Methods Peripheral blood CD4+ T cells and synovial fluid CD4+ T cells derived from RA patients and healthy controls were used to test the effect of SLAT in vitro. CD30 aptamer-SLAT-shRNA chimaeras were generated in vitro and transfected into CD4+ T cells. The effect of CD30 aptamer-SLAT-shRNA chimaeras on Th17 production and differentiation was detected. Results SLAT was expressed mostly in cytoplasm and cell membrane of CD4+ T cells. The protein levels of SLAT in peripheral blood and synovial fluid CD4+ T cells of RA patients were higher than that of healthy controls. The effect of CD30 aptamer-SLAT-shRNA chimaeras on Th17 differentiation was due to its ability to sequester SLAT and prevent it from targeting the transcription factor RORγt. Conclusions This study reveals new evidence of the role of SLAT in Th17 differentiation in CD4+ T cells of RA patients. References [1] Park H, Li Z, Yang XO, et al. A distinct Lineage of CD4+ T cells regulate tissue inflammation by producing interleukin 17. Nat Immunol2005;6(11):1133–1141. [2] Gupta S, Lee A, Hu C, et al. Molecular cloning of IBP, a SWAP-70 homologous GEF, which is highly expressed in the immune system. Hum Immunol2003;64(4):389–401. [3] Canonigo-Balancio AJ, Fos C, Prod’homme T, et al. SLAT/Def6 plays a critical role in the development of Th17 cell-mediated experimental autoimmune encephalomye- litis. J Immunol2009;183(11):7259–7267. [4] Binder N, Miller C, Yoshida M, et al. Def6 Restrains Osteoclastogenesis and Inflammatory Bone Resorption. J Immunol. 2017;198(9):3436–3447. [5] Wheeler LA, Trifonova R,Vrbanac V, et al. Inhibition of HIV transmission in human cervicovaginal explants and humanized mice using CD4 aptamer-siRNA chimeras. J Clin Invest. 2011;121(6): 2401–2412. [6] Takahashi M, Burnett JC, Rossi JJ. Aptamer-siRNA chimeras for HIV. Adv Exp Med Biol. 2015;848:211–234. [7] Zhang P, Zhao N, Zeng Z, et al. Combination of an aptamer probe to CD4 and antibodies for multicolored cell phenotyping. Am J Clin Pathol2010;134(4): 586–593. [8] Song P, Chou YK, Zhang X, et al. CD4 aptamer-RORgammat shRNA chimera inhibits IL-17 synthesis by human CD4(+) T cells. Biochem Biophys Res Commun2014;452(4):1040–1045. Acknowledgements The work was supported by grant 81102274 from the National Natural Science Foundation of China (NSFC) (Hui Lin); grant 10GGYB644SF-023 from the Science and Technology Foundation of Chengdu: (Hui Lin); grant 2017HH0110 from Science and Technology Foundation of International Cooperation of Sichuan Province (Hui Lin) Disclosure of Interest None declared

Direction of arrival (DOA) estimation is an important problem in array signal processing. An effective multiple signal classification (MUSIC) method based on the short-time Fourier transform (STFT) and forward/ backward spatial smoothing (FBSS) techniques for the DOA estimation problem of multiple time-frequency (t-f) joint LFM sources is addressed. Previous work in the area e. g. STFT-MUSIC algorithm cannot resolve the t-f completely or largely joint sources because they can only select the single-source t-f points. The proposed method con¬structs the spatial t-f distributions (STFDs) by selecting the multiple-source t-f points and uses the FBSS techniques to solve the problem of rank loss. In this way, the STFT-FBSS-MUSIC algorithm can resolve the t-f largely joint or completely joint LFM sources. In addition, the proposed algorithm also owns pretty low computational complexity when resolving multiple LFM sources because it can reduce the times of the feature decomposition and spectrum search. The performance of the proposed method is compared with that of the existing t-f based MUSIC algorithms through computer simulations and the results show its good performance.

Background Sjogren syndrome (SS) is a chronic systemic autoimmune disease characterized by exocrine gland inflammation and symptoms of oral and ocular dryness. Anxiety affects as many as 50–70% of persons living with SS. While anxiety is commonly experienced, very little is known concerning the mechanisms of cognitive dysfuction in SS. Objectives To reveal the psychopathology of patients with Sjogren9s syndrome and anxiety disorder. Methods 12 patients with pSS and anxiety disorder (SAS≥50), 11 patients with pSS, and 10 healthy controls were recruited. (1) Self-rating Anxiety Scale (SAS) were used to assess anxiety level of participations. All the subjects went through functional magnetic resonance imaging (fMRI) while listening actively to neutral words, negative words and negative words alternating with neutral ones. Results When subjects listened to neutral words alternating with no words, prefrontal cortex and BA21 were active in patients with pSS and anxiety disorder. When subjects listened to negative words alternating with no words, patients showed increased activity in prefrontal cortex, BA21, anterior cingulate and fusiform. Furthermore, when subjects listen to negative words alternating with neutral words, patients with pSS and anxiety disorder showed more increased activity in prefrontal cortex, anterior cingulate, and caudate nucleus than that of other two groups. Conclusions Anxiety disorder commonly exists in patients with pSS. The pathology of this psychological symptom is poorly understood, which may be one of manifestation of nervous system involvement. fMRI may provide a novel insight into the pathological process accompanying subtle psychiatric disorders commonly experienced by patients with pSS. References Massara A, Bonazza S, Castellino G, et al. Central nervous system involvement in Sjogren9s syndrome: unusual, but not unremarkable–clinical, serological characteristics and outcomes in a large cohort of Italian patients. Rheumatology (Oxford). 2010;49:1540–9. Martinez S, Caceres C, Mataro M, et al. Is there progressive cognitive dysfunction in Sjogren Syndrome? A preliminary study. Acta Neurol Scand. 2010;122:182–8. Barbara M. Segal, Bryon A. Mueller,et al. Disruption of brain white matter microstructure in primary Sjogren9s syndrome: evidence from diffusion tensor imaging. Rheumatology 2010;49:1530–1539. Liu LJ, Zhang XY, He N1, et al. Genetic variation in WDR1 is associated with gout risk and gout-related metabolic indices in the Han Chinese population. Genet Mol Res. 2016 Apr 28;15(2). doi: 10.4238/gmr.15027381. Acknowledgements Thanks are due to Dr. Gong for assistance with the experiments and to YQ. Wang for valuable discussion.There is no financial support or other benefits from commercial sources for the work reported on in the manuscript, or no other financial interests that any of the authors may have, which could create a potential conflict of interest or the appearance of a conflict of interest with regard to the work. Disclosure of Interest None declared

We investigated the asymptotic problem of a kinked interface crack in an orthotropic bimaterial under in-plane loading conditions. The stress intensity factors at the tip of the kinked interface crack are described in terms of the stress intensity factors of the interface crack prior to the kink combined with a dimensionless matrix function. Using a modified Stroh formalism and an orthotropy rescaling technique, the matrix function was obtained from the solutions of the corresponding problem in transformed bimaterial. The effects of orthotropic and bimaterial parameters on the matrix function were examined. A reduction in the number of dependent material parameters on the matrix function was made using the modified Stroh formalism. Moreover, the explicit dependence of one orthotropic parameter on the matrix function was determined using an orthotropic rescaling technique. The effects of the other material parameters on the matrix function were numerically examined. The energy release rate was obtained for a kinked interface crack in an orthotropic bimaterial.

The aim of this study is to evaluate the reliability, validity, and acceptability of the Chinese version of the EORTC QLQ-OES18 in patients with esophageal cancer. The questionnaire was translated according to the guideline of the EORTC. One hundred and forty-nine patients with esophageal cancer from Tianjin Medical University Cancer Institute and Hospital completed the Karnofsky performance scale (KPS) and the simplified Chinese EORTC QLQ-C30/OES18 scales during July 2013 to January 2014. The results were statistically analyzed by Cronbach's α coefficient, Spearman correlation test with multiple strengthen analysis, and Wilcoxon Rank Sum test. The internal consistency (Cronbach's α coefficient) of all four scales (dysphagia, eating, reflux, and pain) was 0.689-0.822, which were satisfactory or near satisfactory. The absolute values of correlation of each scale between EORTC QLQ-OES18 and EORTC QLQ-C30 were 0.002-0.750 while there was no significant difference between groups divided by KPS scores. We confirmed the Chinese version of EORTC QLQ-OES18 appears to be a reliable, valid, and acceptable instrument for measuring the health-related quality of life of patients with esophageal cancer in mainland China.

We report the reversible orbital reconstruction driven by ferroelectric polarization modulates the magnetic performance of ferroelectric/ferromagnetic heterostructure. Inplane Mn orbital occupancy and related interfacial magnetic state are enhanced and weakened by the negative and positive electric-field, respectively. With the aid of ionic liquid, the modulation of magnetism extends to bulk part of the ferromagnet. Our finding not only shows the role of orbits on electrical control of magneism, but also makes the orbits straight forward to the application in microelectronic device.

In recent years, the role of high mobility group box-1 (HMGB1) protein and its receptors in autoimmune diseases has received increasing attention. It has been documented that HMGB1 is associated with disease activity in patients with systemic lupus erythematosus (SLE). This study was undertaken to determine the potential role of receptor for advanced glycation end products (RAGE), one receptor for HMGB1, in the pathogenesis of SLE. Plasma levels of soluble RAGE (sRAGE) from 105 patients with clinical diagnosis of SLE and 43 healthy controls were determined by ELISA. Associations between sRAGE levels and clinical, laboratory characteristics were assessed. The data showed that plasma levels of sRAGE in patients with SLE were significantly lower than those in healthy controls (HC) (P = 0.003). Plasma sRAGE in patients receiving short-period treatment showed an immediate decrease compared with the untreated patients (P = 0.023). In contrast, plasma sRAGE in patients receiving long-period treatment were significantly increased compared to those with short-period treatment (P = 0.000) and comparable with those in HC (P = 0.305). The significant decreased levels of sRAGE in patients with SLE suggest the potential association of RAGE signalling and SLE clinical pathology, whereas, long-period antilupus treatment may counteract the decreased sRAGE levels in patients with SLE.

This paper analyzes the asymptotic problem of a kinked crack in an anisotropic material under antiplane deformation. Using the linear transformation method proposed in this paper, a solution to the asymptotic problem of a kinked crack in an anisotropic material can be obtained from the solution of the corresponding isotropic kinked crack problem. The exact solution of the stress intensity factor for the kinked crack in the anisotropic material is obtained from the solution of the isotropic problem. The effect of the kink angle and two anisotropic parameters on the stress intensity factor is discussed for the inclined orthotropic material as well as the anisotropic material. In order to verify the exact solution of the stress intensity factor, numerical calculations are performed by using finite element analysis.

Graves' disease (GD) is an organ-specific autoimmune thyroid disease; 25-50% of GD patients will develop Graves' ophthalmopathy (GO). The etiology of GD and GO may be multifactorial, but the immune response plays a central role. Many studies have reported that IL-21 has crucial roles in autoimmune diseases. We examined whether IL-21 is associated with the development of GD and GO. The serum concentration of IL-21 was tested in 40 primary GD patients, 42 treated GO patients and 24 healthy controls. Our data show that the serum level of IL-21 is associated with the development of GD. We also made an association study with the IL-21 gene polymorphisms rs4833837, rs907715 and rs13143866 in a comparison of 633 patients and 612 healthy controls from the Chinese population. This case-control association study demonstrated that rs907715 SNP is significantly associated with GD, while the rs13143866 A allele is significantly associated with GO. The haplotypes A-G-G and A-A-A were found at higher and lower frequencies, respectively, in GD patients, suggesting a protective role for A-A-A. However, there were no significant differences in the frequencies of these haplotypes between the GO patients and the control group. We found no association between IL-21 gene polymorphisms and the age of GD onset. We conclude that IL-21 is associated with GD and GO.

With the forthcoming laser intensities (I ≥ 1023 W/cm2), synchrotron radiation in a laser-plasma interaction has attracted particular interest because it can lead to an extremely bright source of γ-rays. Here, a scheme to generate a bright γ-ray pulse with high efficiency is proposed and numerically demonstrated. Using a circularly polarized (CP) laser pulse impinged on a thin foil, a relativistic flying plasma layer is formed. With another counterpropagating CP pulse colliding with the flying layer, it is found that the electrons are efficiently accelerated in the longitudinal direction by the space-charge field. The energetic electrons interact with the counterpropagating CP pulse, producing ultra-brilliant (∼1024 photons/s/mm2/mrad2/0.1%BW) highly dense (∼270nc) femtosecond (∼5 fs) γ-ray pulses. At a moderate laser intensity of 4 × 1022 W/cm2, the fraction of laser energy transferred into the γ-ray pulse is as high as 10%, which is comparable to that previously predicted for an order of magnitude higher in laser intensity. The enhanced γ-photon emission might pave the way for its potential applications in the near future.

In this paper, we propose a Bayesian of inductive cognition algorithm based on Dirichlet process used in virtual reality multimedia information data classification. We present a Bayesian of inductive cognition algorithm framework model for classifying scenes in virtual reality multimedia data. The multimedia can switch between different shots, the unknown objects can leave or enter the scene at multiple times, and the scenes can be classified. The proposed algorithm consists of Bayesian inductive cognition part and Dirichlet process part. This algorithm has several advantages over traditional distance-based agglomerative classifying algorithms. Bayesian of inductive cognition algorithm based on Dirichlet process hypothesis testing is used to decide which merges are advantageous and to output the recommended depth of the scenes. The algorithm can be interpreted as a novel fast bottom-up approximate inference method for a Dirichlet process mixture model. We describe procedures for learning the model...

We report on the novel normally-on/off AlN/GaN high electron mobility transistors (HEMTs) grown by plasma-assisted molecular beam epitaxy. With simple oxygen exposure, the threshold voltage can be tuned from -2.76 V to +1.13 V depending on the treatment time. The gate current was reduced and current-voltage curves show metal-oxide semiconductor diode-like characteristics after oxygen plasma exposure. The extrinsic transconductance of HEMTs decrease with increasing oxygen plasma exposure time due to the thicker Al oxide formed on the gate area. The unity current gain cut-off frequency, fT, and maximum frequency of oscillation, fmax, were 20.4 GHz and 36.5 GHz, respectively for an enhancement-mode HEMT with the gate dimension of 0.4 × 100 μm2. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Ozone treatment of AlN on AlN∕GaN heterostructures produces effective surface passivation and chemical resistance to the AZ positive photoresist developer used for subsequent device fabrication. The ozone-passivated AlN∕GaN high electron mobility transistors (HEMTs) exhibited low gate leakage currents, high gate modulation voltage, and minimal drain current degradation during gate pulse measurements. With an additional oxygen plasma treatment on the gate area prior to the gate metal deposition, enhancement-mode AlN∕GaN high electron mobility transistors were realized. The gate characteristics of the HEMTs treated with the ozone and oxygen plasma behaved in a manner similar to a metal oxide semiconductor diodelike gate current-voltage characteristic instead of a Schottky diode. Drain breakdown voltages of 23 and 43V for d- and e-mode HEMTs were obtained, respectively. For d-mode HEMTs, there was no reduction in the drain current during the gate pulse measurements at frequencies of 1, 10, and 100kHz. For th...

The consistency of measurements in various wind tunnels is of concern to designers and code writers. This study attempts to quantify the variability of wind effects estimates based on tests conducted at six wind tunnel laboratories. Pressure tap measurements were made on wind tunnel models of four buildings. Comparisons were made between estimated 50th percenttiles of (1) peak positive moments in a frame section near the knee joint and (2) peak pressure coefficients of a roof tap nearest a building corner. Modeling of suburban terrain contributes significantly to the variability. Other factors are eave height, wind direction, and frame location within the building. Coefficients of variation were about 10–40%. A subsequent phase of this research entails a detailed analysis of the reasons for the variabilities. The results could help future improvement of wind load factors that account for all relevant uncertainties in the estimation of wind effects and efforts to improve and standardize wind tunnel simulat...

Single layer microstrip antenna arrays with 64-patch and 256-patch applied in millimeter-wave radar front-end are presented. There are two kinds of 64-patch arrays: one is fed from radiating edge a...

A novel Wilkinson power divider using complementary split ring resonators (CSRRs) for harmonic suppression is presented. CSRRs resonators cells are etched at the ground plane below the microstrip line of power divider. A demonstration power divider is designed, fabricated and measured. It agreed with the simulated results well.

The magnetoelectric coupling effect with profound physics and enormous potential applications has provoked a great number of research activities in materials science. Here, we report that the reversible orbital reconstruction driven by ferroelectric polarization modulates the magnetic performance of ferroelectric ferromagnetic heterostructure. Mn in plane orbital occupancy and related interfacial exotic magnetic state are enhanced and weakened by the negative and positive electric field, respectively. Our findings thus not only present a broad opportunity to fill the missing member, orbital in the mechanism of magnetoelectric coupling, but also make the orbital degree of freedom straight forward to the application in microelectronic device., Comment: 26 pages, 5 figures, Accepted by Advanced Materials

863 project of china [2009aa03z305]; national natural science foundation of china [60876031]

Different type HTS filters for the applications in satellite microwave receivers have been developed, aiming for space communications and astronomy observations. The HTS filters have been integrated with cryogenic low noise amplifiers and Stirling cryocoolers forming receiver front-end subsystems, which have passed all space qualification environmental tests. The first Chinese space HTS subsystem was taken into space with a civilian experimental satellite for new technology on October 14, 2012. Data received from this satellite show that the HTS filter is working on orbit perfectly. Moreover, an ultra-wide band HTS filter with a notch has been developed for the applications of deep space exploration. A novel K-band receiver with both HTS passive and active devices is under development and is expected to work in the planned space VLBI system by 2020.

Oral lichen planus (OLP) is a common oral inflammatory disease affecting about 1-2% of the general adult population. As with European families who are diagnosed with OLP, the Chinese family who we studied was diagnosed with a severe form of oral reticular and erosive lesions; moreover, two of the five affected individuals developed oral cancer at an early age. A whole-genome genotyping scan with linkage analysis was performed using the 10K SNP array to investigate the genetic susceptibility of the Chinese family to OLP, which revealed one maximal nonparametric LOD score of 2.32 (P = 0.0156) for SNP marker rs2372736, defined at the chromosome 3p14-3q13 region encompassing 19 SNPs. Blood samples were obtained from 10 members of the family, which included the grandmother, father and mother, and the children altogether. The grandfather is dead, but the family members remembered he also suffered from the same disease. Chromosome 3p14-3q13 was identified as the candidate gene region for OLP; this information provides a foundation for further identification of the gene responsible for OLP.

We describe electrodeposition of a (Cu2O)-(ZnO nanowire) thin film p-n junction solar cell. The efficiency of this prototype large junction-area nanostructured cell is 1.6 times that of a planar cell fabricated from the same materials.

In a conventional spin-valve magnetic memory cell, where a nonmagnetic metal is sandwiched between two-magnetic layers, the magnetization of one magnetic layer (the pinned layer) is fixed by an anti-ferromagnetic FeMn layer (the pinning layer). However, the FeMn can be easily oxidized, creating instability. In this paper, we demonstrate a new spin-valve magnetic cell, where the magnetization of one magnetic layer is fixed through the spontaneous formation of a single-domain due to nanopatterning, and pinning layers (such as FeMn) are no longer required. Magnetic multilayer samples with a NiFe(10 nm)/Co(1 nm)/Cu(13 nm)/Co(10 nm)/NiFe(2 nm) structure were deposited on a SiO/sub 2/ substrate using a DC sputtering system. The samples were patterned using nanoimprint lithography and an ion milling process.

We propose a new scheme for object recognition in robot vision. The proposed scheme uses the HSI model as the input. A gradient algorithm is used to obtain the edge estimation of objects. The edge points are regarded as stimulus and the other points as nonstimulus. The stimulus context of all the possible positions of objects is coded in stimulus vectors. Then a HMM-based vision system for scene analyse and object recognition is presented. This method has been tested using our mobile service robot called ARNOLD and real data of Columbia Object Image Library (COIL-20). Through these experiments, we have demonstrated the generalisation capabilities and robustness of object recognition and classification.

A study of the polarization characteristic of a Co:MgF2 laser with a 1320-nm YAG pumping laser at room temperature is reported. The thresholds, output energies, and efficiencies of the laser are given at the various polarization states. The more intensive emission is in the pi-polarization pump laser and sigma-polarization laser operation. Performances of the Co:MgF2 lasers are similar for the polarized and unpolarized laser pumping along the optical axis of the crystal.

A multi-sample Cs sputter negative-ion source, equipped with a conical-geometry, W-surface-ionizer has been designed and fabricated that permits sample changes without disruption of on-line accelerator operation. Sample changing is effected by actuating an electro-pneumatic control system located at ground potential that drives an air-motor-driven sample-indexing-system mounted at high voltage; this arrangement avoids complications associated with indexing mechanisms that rely on electronic power-supplies located at high potential. In-beam targets are identified by LED indicator lights derived from a fiber-optic, Gray-code target-position sensor. Aspects of the overall source design and details of the indexing mechanism along with operational parameters, ion optics, intensities, and typical emittances for a variety of negative-ion species will be presented in this report.

A new measurement system for microwave property study has been developed. Modified from the standard quasi-optical dielectric resonator technique, the sapphire cylinder resonator excited with whispering gallery modes has a narrow slit along the radius, within which a piece of small-sized single crystal or thin film sample can be positioned. Sandwiched by two pieces of YBCO films, the resonator is sealed in a specially designed vacuum vessel, which is soaked in liquid 4He. A microwave signal is coupled to the vacuum vessel by stainless steel thin wall waveguides and then to the resonator by sapphire waveguides. Coupling between the resonator and the two sapphire waveguides can be controlled accurately during the measurement. Furthermore, a decompressed liquid 4He port has been designed in the vacuum vessel so as to extend the measurement to lower temperatures down to 2.6 K. A high-quality single crystal pnictide superconductor of BaFeNiAs was used for testing.

After we developed a saturated iron core type 35 kV/90 MVA superconductive fault current limiter and installed the device in a transmission network at Puji substation of China Southern Power Grid for live-grid operation in 2007, we continued our efforts in advancing this technology. A 220 kV/300 MVA device has been designed, manufactured and factory tested. This device differs from the 35 kV device in its form of electrical insulation even though the two devices have the same working principle and similar core structure. Improvements in the dc magnetization circuit and the cryogenic system were also achieved. This 220 kV/300 MVA superconductive fault current limiter has been installed and has passed all field tests at Shigezhuang substation in Tianjin, China. Trial operation is underway. This paper introduces the major design parameters, key functional specifications and some testing results of the device.

CdS nanocrystal-sensitized solar cells (NCSSCs) were investigated by using polyaniline (PANI) as a replacement for conventional platinum counter electrode. The growth time of the NCs significantly affects the solar cell performance. At an optimum growth, the NCSSCs exhibit 0.83% of the conversion efficiency in comparison to 0.13% for the identical cells without CdS NCs. Electrochemical impedance spectroscopy showed that the charge transfer in the solar cells with CdS nanocrystals was improved. The enhanced overall energy conversion efficiency by NCs is attributed to improved light absorption and suppressed recombination rate of interfacial charges with injection, resulting in significantly improved charge transfer and electron life time. In addition, the PANI electrodes with large surface area and ideal corrosion-inertness toward polysulfide redox exhibit promising application potential as a counter electrode for NCSSCs. This study demonstrates that the solution grown CdS nanocrystals and polyaniline are ...

n-ZnO/p-GaN heterojunction light-emitting diodes with and without a sandwiched AlN layer were fabricated. The electroluminescence (EL) spectrum acquired from the n-ZnO/p-GaN displays broad emission at 650 nm originating from ZnO and weak emission at 440 nm from GaN, whereas the n-ZnO/AlN/p-GaN exhibits strong violet emission at 405 nm from ZnO without GaN emission. The EL intensity is greatly enhanced by inserting a thin AlN intermediate layer and it can be attributed to the suppressed formation of the GaOx interfacial layer and confinement effect rendered by the AlN potential barrier layer.

A simple method is reported for fabrication of AlN/GaN MOS-HEMTs. Ultra-thin Al 2 O 3 , which is formed using thermal oxidation of evaporated Al, was used for surface passivation and as a gate dielectric. Prior to formation of Al 2 O 3 , the Al protects the very sensitive AlN epilayer from exposure to processing liquid chemicals. Fabricated two-finger AlN/GaN MOS-HEMTs with 3 m gate length and 200 m gate width showed good gate control of drain currents up to a gate bias of 3 V and achieved a maximum drain current, I DSmax , of ~900~mA/mm. The peak extrinsic transconductance, G max , of the device is ~100~mS/mm at V DS = 8=V. Capacitance-voltage ( C - V ) characteristics of Al 2 O 3 /AlN/GaN circular test MOS structures were observed and measured. They exhibited no hysteresis, indicating the good quality of the thermally grown Al 2 O 3 for realising AlN/GaN MOS-HEMTs for high power and high frequency applications.

Enhancement mode AlN/GaN high electron mobility transistors (HEMTs) were fabricated from originally depletion-mode structures using oxygen plasma treatment on the gate area prior to the gate metallization. Starting with a depletion mode AlN/GaN HEMT, the threshold voltage of the HEMT could be shifted from −3.2 to 1 V depending on the oxygen plasma treatment time to partially convert the AlN barrier layer into Al oxide. The gate current was reduced and the current-voltage curves show metal-oxide semiconductor diodelike characteristics after oxygen plasma treatment.

The effects of 10MeV electron irradiation on AlGaN∕GaN and AlN∕GaN heterojunctions grown by molecular beam epitaxy are reported. The irradiation increases the resistivity of the GaN buffer due to compensation by radiation defects with levels near Ec−1eV and decreases the mobility of the two-dimensional electron gas (2DEG) near the AlGaN∕GaN (or AlN∕GaN) interface. The bulk carrier removal rate in the GaN buffer is the same for both types of structures and similar to carrier removal rates for undoped n-GaN films. In structures with a density of residual donors of ∼1015cm−3, irradiation with electron doses of ∼5×1015cm−2 renders the buffer semi-insulating. The 50% degradation of the 2DEG conductivity happens at several times higher doses (close to 3×1016cm−2 versus 6.5×1015cm−2) for AlN∕GaN than for AlGaN∕GaN structures, most likely because of the lower thickness of the AlN barrier.

Low defect AlN/GaN high electron mobility transistor (HEMT) structures, with very high values of electron mobility (>1800 cm2/V s) and sheet charge density (>3×1013 cm−2), were grown by rf plasma-assisted molecular beam epitaxy (MBE) on sapphire and SiC, resulting in sheet resistivity values down to ∼100 Ω/◻ at room temperature. Fabricated 1.2 μm gate devices showed excellent current-voltage characteristics, including a zero gate saturation current density of ∼1.3 A/mm and a peak transconductance of ∼260 mS/mm. Here, an all MBE growth of optimized AlN/GaN HEMT structures plus the results of thin-film characterizations and device measurements are presented.

The origin of hysteresis in capacitance-voltage (C-V) characteristics was studied for Schottky diodes prepared on AlGaN∕GaN transistor structures with GaN (Fe) buffers. The application of reverse bias leads to a shift of C-V curves toward higher positive voltages. The magnitude of the effect is shown to increase for lower temperatures. The phenomenon is attributed to tunneling of electrons from the Schottky gate to localized states in the structure. A technique labeled “reverse” deep level transient spectroscopy was used to show that the deep traps responsible for the hysteresis have activation energies of 0.25, 0.6, and 0.9eV. Comparison with deep trap spectra of GaN buffers and Si doped n-GaN films prepared on GaN buffers suggests that the traps in question are located in the buffer layer.

Effects of a resistive sheet on the field emission characteristics of carbon films have been studied systematically by monitoring both the emission I–V curves and the emission image. We demonstrate that the emission current of individual sites with different field enhancement factors β can be controlled by the resistive sheet and hence that the homogeneity of the emission sites can be significantly improved. This implies that the use of a local resistor to limit the emission could be one possibility to homogenize emission sites in display device fabrication.

Agro-industrial wastes are a low-cost and sustainable resource for the production of both bulk and specialty chemicals. A number of natural flavors can also be produced from them via microbial transformation. Vanillin is one of the most important flavoring compounds in the food industry. Research regarding its biotechnological production from ferulic acid AU3 recovered from agro-food industry byproducts and wastes has received a great impulse in the last years. Several byproducts from the cereal industry (maize, rice, and wheat) and the sugar beet pulp have been examined as a source of ferulic acid that has been extracted at high yield from all of them. Both crude hydrolysates, obtained from the mentioned plant source and purified ferulic acid, have been used as substrate sources for the biological production of ‘natural’ vanillin. The highest vanillin molar yields have been obtained with the use of fungi or actinomycetes as catalysts, although very promising results have been recently obtained with nonfilamentous microorganisms. On the whole, the production of vanillin from agro-food industry byproducts represents an opportunity to produce this flavor in a new, economically and environmentally sustainable way, which also allows for the valorization of waste matrixes.