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Porcine respiratory disease complex (PRDC) is one of the most challenging health concerns for pig production worldwide. The aim of the present study was to determine the prevalence of pathogens associated with PRDC, including porcine reproductive and respiratory syndrome virus (PRRSV) and porcine circovirus type 2 (PCV2) and bacterial agents, such as Streptococcus suis, Haemophilus parasuis and Actinobacillus pleuropneumoniae, in clinically healthy pigs in Eastern China. Molecular detection revealed positive single‐pathogen detection rates of 59.9%, 27.2%, 52.3%, 33.2% and 0.4% for PCV2, PRRSV, S. suis, H. parasuis and A. pleuropneumoniae, respectively. Co‐infection with more than one pathogen was frequently detected in these samples, with PCV2/S. suis, H. parasuis and PCV2/H. parasuis mixed infection rates of 35.4%, 33.2% and 21.6%, respectively, and PCV2/S. suis/H. parasuis and PRRSV/PCV2/S. suis co‐infection rates of 21.6% and 6.2%, respectively. These results suggest that mixed infections are prevalent among PRDC cases in swine, which may pose a greater threat to the health of herds compared with single‐pathogen infections., These results suggest that mixed infections are prevalent among PRDC cases in swine, which may pose a greater threat to the health of herds compared with single‐pathogen infections.

This study was to explore the potential mechanism of naprapathy in treating neuropathic pain (NP) after brachial plexus injury (BPI).Totally 72 rats were randomly divided into normal group, model control group, and naprapathy group (n=24 per group). A right upper-limb chronic NP model was established, and naprapathy was administered at C5-T1 Jiaji Points on 4th day after modeling. Naprapathy was performed for 15 min once daily with a frequency of 60 per minute. The treatment was applied for altogether 28 days. Cold pain threshold and mechanical pain threshold were measured 1 day before modeling, 3 days after modeling, and 7, 14, 21 and 28 days after naprapathy; 7, 14, 21 and 28 days after naprapathy, rats were killed and the β-endorphin expression and γ-aminobutyric acid (GABA) content were detected in the thalamus.After 14-day treatment, there was significant difference of mechanical pain threshold between the naprapathy group and the normal group (P0.05); after treatment for 21 and 28 days, there was no significant difference between the naprapathy group and the normal group (P0.05); after 28-day naprapathy, there was significant difference of β-EP expression between the normal group and the naprapathy group (P0.05), while the difference between model control group and naprapathy group was statistically significant (P0.05). After 14-day treatment, there was significant difference of GABA content between the model control group and the naprapathy group (P0.05). After 28-day treatment, significant difference was also found between the model control group and the naprapathy group (P0.05).After naprapathy, chronic NP is attenuated in rats with BPI, which might be ascribed to the upregulation of β-endorphin and GABA.

Electrodialysis (ED) is an alternative to the conventional thermal regeneration of high-salt solutions used in air conditioning systems (ACSs). In this work, a simplified mathematical model was developed to describe the solute and water transport. The solute hydration number and free water content were proposed to characterize the solute hydration properties. A laboratory-scale ED regeneration system was set up to investigate the regeneration performance of three kinds of high-salt solutions (aqueous LiCl, LiBr and CaCl2 solutions) at various initial concentrations and current densities. The results demonstrate good agreement between numerical and experimental findings. The initial concentration and applied current density have great impacts on ED performance. Firstly, higher initial concentration generally results in lower membrane permselectivity, current efficiency, solute and water transfer rate, and higher energy consumption. Secondly, higher current density has a positive effect on solute and water transport but leads to more energy consumption. The solute hydration number and free water content both decrease with increasing initial concentration. The appropriate mass concentrations of 15%, 25% and 15% are respectively suggested for aqueous LiCl, LiBr and CaCl2 solutions when applying ED in ACSs to ensure responsible performance.

In order to solve the problem of poor regeneration performance of the solar solution dehumidification air conditioning regeneration system under high temperature and high humidity weather conditions. In this paper, a novel vacuum membrane distillation (VMD) solution regeneration method was proposed for a solution desiccant air conditioning system, and a theoretical study of this novel regenerator is performed. Through the analysis of heat and mass transfer, the mathematical model of VMD regeneration is established, and the mathematical model is verified by experiments. The results indicated that VMD regenerator not only could increase the regenerate rate but also could exhibit higher energy utilization efficiency. At the same concentration, the VMD regenerator has a higher regeneration performance, and the regeneration rate is 1.6–2.4 times that of the internal heat type regenerator, and the 4.5–6 times that of the adiabatic regenerator.

Vitamin A (VA), which is stored in several forms in most tissues, is required to maintain metabolite homeostasis and other processes, including the visual cycle, energy balance, epithelial cell integrity, and infection resistance. In recent years, VA molecules, also known as retinoids, have been extensively explored and used in the treatment of skin disorders and immune-related tumors. To date, several observational and interventional studies have explored the relationship between VA status and the pathogenesis of diabetes. In particular, VA micronutrients have been shown to regulate pancreatic development, β-cell function, pancreatic innate immune responses, and pancreatic stellate cells phenotypes through multiple mechanisms. However, there are still many problems to be proven or resolved. In this review, we summarize and discuss recent and available evidence on VA biological metabolism in the pancreas. Analysis of the effects of VA on metabolism in the pancreas will contribute to our understanding of the supportive physiological roles of VA in pancreas protection.

This paper proposes a novel solar vacuum membrane distillation (VMD) regeneration for liquid desiccant air conditioning (LDAC) system, and establishes a mathematical model of the VMD regeneration process and traditional thermal (TH) regeneration process based on the heat and mass balance. The corresponding simulation model was established by using Matlab software, and the model was verified by previous experiments. The results show that: the model results are consistent with the previous experimental results, and the maximum error is less than 6%. Model simulations are carried out to study the regeneration performance under various operating parameters and climatic conditions, meanwhile the comparison the solar power consumption for regenerating one kilogram desiccant between the VMD regeneration and TH regeneration. Results demonstrate that when the air temperature is less than 32 °C, the humidity ratio is higher than 19 g/kg, and the air flow rate is less than 0.13 kg/s, the VMD regenerator solution regeneration effect is better than the conventional thermal regenerator. VMD regeneration is more suitable for solution regeneration in wet areas than TH regeneration. Furthermore, when the solution temperature is lower than 60 °C, VMD regeneration outlet concentration is higher than TH regeneration. VMD regeneration is more suitable for low-grade energy. Analyze the solar power consumption for regenerating one kilogram desiccant found that the VMD regeneration saves 10–37% energy than TH regeneration. Through economic analysis, it is found that the VMD regenerator can save 582.4 kWh of electricity per year compared to the TH regenerator. According to the cost recovery calculation formula, the cost recovery period can be calculated as 13.8 years.

A spatial separated source delivery (SSSD) method has been proposed to alleviate parasitic reactions between group III precursors and ammonia (NH3) in gas phase using the MOCVD. AlGaN alloys and GaN films grown on sapphire has been prepared with this method. The influence of parasitic reactions on the qualities and properties of AlGaN and GaN films is investigated in detail. High-resolution X-ray diffraction (HRXRD) measurements show that the aluminum composition in materials rises up close to the ratio of trimethylaluminum (TMAl) supply when the supply ratio of TMAl is 0.2, 0.3 and 0.4 respectively, which demonstrates that the parasitic reactions are suppressed mostly. In-situ monitor reflectometer spectra for GaN show that the growth rate gets a 20% increase in comparison with materials grown without the SSSD method. Subsequently, the relationship between parasitic reactions and other reaction types are elucidated. The effect of the SSSD method on parasitic reactions is also systematically studied. Reactions are controlled to change from combination reactions to pyrolysis reactions and surface reactions with the SSSD method. A 2-inch GaN/AlGaN heterostructure is also prepared to evaluate the uniform electrical properties grown with this method. The result indicates that the SSSD method provides a better way to prepare high-quality III-nitride materials, especially for AlN and related alloys.

Experimental investigations were conducted on a diesel engine to evaluate the effects of hydrogen addition on engine combustion, unregulated gaseous emissions and particulate emissions based on the Japanese 13-mode testing cycle. A diesel–hydrogen co-operated combustion strategy is proposed in which hydrogen is naturally aspirated into the diesel engine to substitute 10, 20 and 30% of the total fuel energy at 10 selected modes and diesel is used as the sole fuel for the other 3 modes. Gradual increase of peak in-cylinder pressure and heat release rate is observed at medium and high engine loads. Pre-ignition might occur at high engine load and speed. Cyclic variation of the indicated mean effective pressure and maximum pressure derivative increased with hydrogen addition. The brake specific emissions of acetaldehyde (CH3CHO), alkenes (C2H4, C3H6 and C4H6), arenes (C6H6, C7H8 and C8H10) and particulate mass can be evidently reduced. However, with H30 operation, the weighted total HC and formaldehyde (HCHO) increased by around 27% and 8%, respectively, while NOx increased by around 17%. The simultaneous decrease of particle size and number are believed to be associated with the inhibition effect of hydrogen on soot particle formation based on the HACA (H2 abstraction and C2H2 addition) mechanism.

The influence of excessive H2 flow during barrier growth on optical and electrical properties of InGaN light-emitting diodes (LEDs) are investigated in this study. The room temperature photoluminescence of LEDs decays with excessive H2 treatment. Temperature-dependent photoluminescence (TDPL) reveals an increase of the density and a decrease of the activation energy of deep non-radiative recombination centers in the H2 treated LEDs. The external quantum efficiency (EQE) of the LEDs suffers from excessive H2 treatment. The leakage current on the reverse and forward sides of the LEDs are reduced significantly when treated with H2, which may be due to the suppressed Poole–Frenkel effect.

The interface, optical and electrical properties of InGaN light emitting diodes (LEDs) with different H2 flow treatment during the barrier growth are investigated in this study. With H2 treatment, the interface between the quantum well and barrier becomes rougher and the photoluminescence intensity decreases. The external quantum efficiency of the LEDs with 600 sccm (2.7%) H2 treatment has the best performance among the samples. Both the forward and reverse leakage currents of the samples are reduced significantly when treated with H2. Among the samples, a H2 flow with 600 sccm (2.7%) gives the best performance.

This article presents a novel method to apply on reducing the period limitation in laser interference lithography (LIL) by preparing a kind of nanowire arrays with the period $${\uplambda }/(4\hbox {n}\times \hbox {sin}{\uptheta }$$ ) instead of $${\uplambda }/(2\hbox {n}\times \hbox {sin}{\uptheta }$$ ). Nanowire arrays with periods of 150 and 125 nm on Si (100) substrate were fabricated successfully with a 325 nm He–Cd continuous wave laser as a light source, based on the combined process of dry etching and wet etching. It is the slight over-etching in the dry etching process and keeping the fluorine carbon organic polymer layer intact during whole process of wet etching that guaranteed the nanowire generated from the platform between two adjacent etched facets. The width of the nanowire as narrow as 50 nm was fabricated by this method, which is much more interesting for the research on the small size effect. This method is proved to circumvent the period formula limitation of the traditional LIL and makes the preparation of nanostructures with much smaller size more feasible.

Human visual system (HVS) can perceive the difference between two retinal images to create a mental image with depth perception, which is the result of two binocular interactions, i.e., binocular fusion and suppression. According to perceptual attributes of binocular interactions, in this paper, a full-reference stereoscopic image quality assessment (SIQA) method is proposed based on the mechanisms of binocular fusion and suppression. There are two kinds of information in stereoscopic images: monocular information which is visible in only one view, and binocular information which is visible in two views. HVS adopts two ways to deal with the binocular information, one is binocular fusion which deals with the information with similar content and small disparity, the other is binocular suppression which deals with the information with dissimilar content or large disparity. Therefore, the proposed method firstly divides a distorted stereoscopic image into occluded, pseudo-binocular fusion and pseudo-binocular suppression regions. Then three methods are respectively adopted to assess the quality of the three regions and the three quality indices combine into one to represent the overall quality of the distorted stereoscopic image. Finally, the predictive performance of the proposed method is evaluated and compared with existing methods in terms of consistency, cross-image and cross-distortion, and robustness. Experimental results show that the proposed SIQA method outperforms other methods and can predict human visual perception of stereoscopic image more accurately.

Experiments were conducted to investigate the combustion and emission characteristics of a diesel engine with addition of hydrogen or methane for dual-fuel operation, and mixtures of hydrogen–methane for tri-fuel operation. The in-cylinder pressure and heat release rate change slightly at low to medium loads but increase dramatically at high load owing to the high combustion temperature and high quantity of pilot diesel fuel which contribute to better combustion of the gaseous fuels. The performance of the engine with tri-fuel operation at 30% load improves with the increase of hydrogen fraction in methane and is always higher than that with dual-fuel operations. Compared with ULSD–CH 4 operation, hydrogen addition in methane contributes to a reduction of CO/CO 2 /HC emissions without penalty on NO x emission. Dual-fuel and tri-fuel operations suppress particle emission to the similar extent. All the gaseous fuels reduce the geometry mean diameter and total number concentration of diesel particulate. Tri-fuel operation with 30% hydrogen addition in methane is observed to be the best fuel in reducing particulate and NO x emissions at 70 and 90% loads.

A method is suggested to improve the characteristics of light emitting diodes (LEDs) by using p-GaN structure with heavily Mg-doping grown at low temperature in full N-2 environment. The LED exhibits a 36.4% enhancement in light output power (LOP) at 222Acm(-2) due to the higher hole concentration as compared to the normal p-GaN layer. Meanwhile, the experimental results prove that the optimized LED structure shows reduced efficiency droop behavior, smaller peak wavelength blueshift and narrower electroluminescence (EL) spectrum broadening.

Personal heating clothing systems (PHCS) incorporated with electrical heating elements have shown its great potential to help occupants attain thermal comfort in cold built environments. Presently there is a lack of a comprehensive study to optimize the PHCS's performance. In this work, a newly developed complete 3D model was used to systematically examine the factors affecting the PHCS's heating performance in various cold unheated built environments. Effects of ambient temperature, clothing insulation, heating power, heating mode and metabolic rate on the PHCS's performance were investigated by performing a numerical parametric study. Validation data have demonstrated that the 3D model could precisely predict human thermophysiological responses while wearing PHCS in the built environment. At 15.0 °C indoor temperature and metabolic rate of 1.6 met, wearing a PHCS with thermal insulation of 1.0 clo and heating power of 20 W could help occupants attain thermal comfort. It was also found that compared with continuous heating, intermittent heating at a high heating frequency could contribute to saving energy without compromise of body temperature reduction. Furthermore, metabolic rate has a significant impact on thermophysiological responses and the mean heaters' temperature. Hence, the selection and operation of a PHCS should be based on the nature of occupant activities. Occupants are advised to adjust the heating power to a lower level when performing more demanding activities because the need for auxiliary heating is not as high as that in the case when occupants are resting or performing seated office activities.

GaN-based light emitting diodes (LEDs) with nano truncated cone SiO2 passivation layer via laser interference lithography and inductively coupled plasma dry etching technology were fabricated. The sidewall profile of the nano truncated cones was optimized by adjusting the etching process to obtain high fill factor. The light output power and electroluminescence intensity of the LEDs with textured SiO2 surface show better results than the conventional LEDs without SiO2 layer. At an injection current of 20 mA, the enhancement of the light output power is about 64 %. Moreover, the reverse leakage current, under a reverse bias of −5 V, is obviously reduced in contrast to the conventional LEDs. The method of texturing the passivation layers is proved to be an alternative method to improve both the optical and electrical performances of GaN-based LEDs.

AlxGa1−xN/GaN high-electron-mobility transistor (HEMT) structures with Al composition ranging from x = 0.13 to 0.36 are grown on sapphire substrates by low-pressure metalorganic chemical vapor deposition (LP-MOCVD). The effects of Al content on crystal quality, surface morphology, optical and electrical characteristics of the AlGaN/GaN heterostructures have been analyzed. Although high Al-content (36%) heterostructure exhibits a distinguished photoluminescence peak related to recombination between the two-dimensional electron gas and photoexcited holes (2DEG-h), its crystal quality and rough surface morphology are poor. 2DEG mobility increases with the Al content up to 26% and then it apparently decreases for high Al-content (36%) AlGaN/GaN heterostructure. The increase of sheet carrier density with the increase of Al content has been observed. A high mobility at room temperature of 2105 cm2/V s with a sheet carrier density of ns = 1.10 × 1013 cm−2, for a 26% Al-content AlGaN/GaN heterostructure has been obtained, which is approaching state-of-the-art for HEMT grown on SiC. Sheet resistance as low as 274 Ω/□ has also been achieved.

The 256×1 linear array of multiple quantum wells infrared photodetector (QWIP) is designed and fabricated for the peak response wavelength at λ P = 14.6 μm. The response spectral width is bigger than 2.2 μm. The two-dimensional (2D) diffractive coupling grating has been formed on the top QWIP photosensitive pixel for coupling the infrared radiation to the infrared detective layers. The performance of the device at V B = 3 V and T = 45 K has the responsibility 4.28×10−2 (A/W), the blackbody detectivity D b* = 5.14×109 (cm·Hz1/2/W), and the peak detectivity D λ * = 4.24× 1010 (cm·Hz1/2/W). The sensor pixels are connected with CMOS read out circuit (ROC) hybridization by indium bumps. When integral time is 100 μs, the linear array has the effective pixel of QWIP FPA N ef of 99.2%, the average responsibility $$ \overline R $$ (V/W) of 3.48×106 (V/W), the average peak detectivity D λ * of 8.29×109 (cm·Hz1/2/W), and the non-uniformity UR of 5.83%. This device is ready for the thermal image application.

The effects of GaN cap layer thickness and doping type on photoluminescence (PL) are investigated for InGaN/GaN quantum wells (QWs), which are deposited on a C-plane sapphire substrate by metal organic chemical vapor deposition (MOCVD). As for the results, the QWs capped with an unintentional doped (un-doped) GaN layer show a linear PL blue shift behavior with decreased cap layer thickness, while for the QWs capped with a heavy n- or p-doped GaN layer none of the similar behaviors are observed until the cap layer is less than 25 nm. These phenomena are well explained by introducing the effects of upward surface band bending. Surface polarization discontinuity and surface states are considered as the origins of the surface band bending. Furthermore, the actual surface band bending value of the un-doped GaN is also extracted as Eb = 1.54 ±0.08 eV from the linear PL blue shift behavior.

Photoluminescence (PL) is a nondestructive and powerful method to investigate carrier recombination and transport characteristics in semiconductor materials. In this study, the temperature dependences of photoluminescence of GaAs-AlxGa1-xAs multi-quantum wells samples with and without p-n junction were measured under both resonant and non-resonant excitation modes. An obvious increase of photoluminescence(PL) intensity as the rising of temperature in low temperature range (T xGa1-xAs quantum wells sample with p-n junction under non-resonant excitation. The origin of the anomalous increase of integrated PL intensity proved to be associated with the enhancement of carrier drifting because of the increase of carrier mobility in the temperature range from 15 K to 100 K. For non-resonant excitation, carriers supplied from the barriers will influence the temperature dependence of integrated PL intensity of quantum wells, which makes the traditional methods to acquire photoluminescence characters from the temperature dependence of integrated PL intensity unavailable. For resonant excitation, carriers are generated only in the wells and the temperature dependence of integrated PL intensity is very suitable to analysis the photoluminescence characters of quantum wells.

Light-emitting diodes (LEDs) in the wavelength region of 535–570 nm are still inefficient, which is known as the “green gap” problem. Light in this range causes maximum luminous sensation in the human eye and is therefore advantageous for many potential uses. Here, we demonstrate a high-brightness InGaN LED with a normal voltage in the “green gap” range based on hybrid multi-quantum wells (MQWs). A yellow-green LED device is successfully fabricated and has a dominant wavelength, light output power, luminous efficiency and forward voltage of 560 nm, 2.14 mW, 19.58 lm/W and 3.39 V, respectively. To investigate the light emitting mechanism, a comparative analysis of the hybrid MQW LED and a conventional LED is conducted. The results show a 2.4-fold enhancement of the 540-nm light output power at a 20-mA injection current by the new structure due to the stronger localization effect and such enhancement becomes larger at longer wavelengths. Our experimental data suggest that the hybrid MQW structure can effectively push the efficient InGaN LED emission toward longer wavelengths, connecting to the lower limit of the AlGaInP LEDs’ spectral range, thus enabling completion of the LED product line covering the entire visible spectrum with sufficient luminous efficacy.

A promising technique of lateral epitaxial overgrowth, namely CantiBridge epitaxy, is developed and demonstrated in order to reduce the threading dislocation density in GaN films. Using metalorganic chemical vapor deposition, the GaN films are grown on patterned sapphire fabricated by wet chemical etching, instead of traditional dry etching. The image of atomic force microscopy shows that the threading dislocations in CantiBridge-epitaxy GaN are reduced sharply, which makes a promising to realize the high-performance GaN-based optoelectronic devices.

The wavelength of the responsive peak for GaAs/Al0.3Ga0.7As multi-quantum well (MQW) infrared detectors was measured to be λ = 6.29 μ m at 77 K. Based on the theory of electron interference, the results calculated for the MQW structure indicate that there may be a series of separated conduction states above the barriers, on which the electrons can propagate along the direction perpendicular to well/barrier interfaces. For the quantum well parameters given in this article, the wavelength of light absorbed is calculated to be 6.29 μm when optical excitations occur for which electrons transit from Fermi level in quantum wells to the first conduction state E 1 above the barriers. The theoretical value for the responsive peak wavelength is in very good agreement with the measurement result. This shows that the wavelength of the responsive peak resulted from electron interferences for the MQW infrared detectors.

The new developed maskless lateral-epitaxial-overgrowth technique, in which the striped substrates are patterned by wet chemical etching, is systematically investigated using scanning electron microscopy, X-ray diffraction, and atomic force microscopy (AFM). Wing tilt is measured for the GaN films on patterned substrates with a range of "fill factor" (ratio of groove width to stripe period) and for the GaN in different growth time. It is found that changes in these parameters have a significant effect on the extent and distribution of wing tilt in the laterally overgrown regions relative to the GaN directly on the sapphire substrate. Increasing the thickness of GaN films is benefit to reduce wing tilt. The tilt is avoided in the GaN films with 4.5 mu m thickness and fill factor for 0.46. The full-width at half-maximum of X-ray rocking curves of the asymmetric diffraction peaks and the image of AFM both show that the threading dislocations in the developed lateral epitaxial overgrowth of GaN films are reduced sharply. The GaN template could be used as an excellent substrate to fabricate high-performance optoelectronic devices. (c) 2006 Elsevier B.V. All rights reserved.

Lattice-matched InGaP epilayers on GaAs (001) and InGaP/GaAs heterojunction bipolar transistors (HBTs) were successfully grown by solid-source molecular beam epitaxy (SSMBE) with a GaP decomposition source. A 3 μm thick InGaP epilayer shows that low temperature photoluminescence (PL) peak energy is as large as 1.998 eV, full width at half maximum (FWHM) is 5.26 meV, which is the smallest ever reported, and X-ray diffraction (XRD) rocking curve linewidth is as narrow as that of GaAs substrate. The electron mobilities at room temperature of nominally undoped InGaP layers obtained by Hall measurements are comparable to similar InGaP epilayer grown by solid-source molecular beam epitaxy (SSMBE) with other sources or other growth techniques. The large area InGaP/GaAs HBTs show very good Dc characteristics.

We demonstrate the fabrication of high-quality GaAs/AlGaAs multiple quantum wells (MQWs) at very low temperature by solid-state source molecular beam epitaxy. The key to our method is to maintain a critical arsenic pressure or As/Ga beam equivalent pressure ratio to ensure a sharp heterointerface and a low defect density. A sharp heavy-hole excitonic photoluminescence (PL) signal was observed from the MQWs with a well width of 7.5 nm and a barrier width of 4 nm grown at 360°C. The PL linewidth of the QW heavy-hole exciton is 3 meV measured at 77 K. This emission linewidth is far narrower than that in a sample with the same structure grown at the standard growth temperature. The resistivity of the as-grown sample is about 5×106 Ωcm and increases to 5×107 Ωcm after postgrowth annealing at 700°C. The low growth temperature and high optical quality as well as the high resistivity make this kind of material suitable for use in ultrafast optical and monolithic integrated optoelectronic devices.

The indium segregation in InGaN well layer is confirmed by a nondestructive combined method of experiment and numerical simulation, which is beyond the traditional method. The pre-deposited indium atoms before InGaN well layer growth are first carried out to prevent indium atoms exchange between the subsurface layer and the surface layer, which results from the indium segregation. The uniform spatial distribution of indium content is achieved in each InGaN well layer, as long as indium pre-deposition is sufficient. According to the consistency of the experiment and numerical simulation, the indium content increases from 16% along the growth direction and saturates at 19% in the upper interface, which cannot be determined precisely by the traditional method.

Electroacupuncture has traditionally been used to treat pain, but its effect on pain following brachial plexus injury is still unknown. In this study, rat models of an avulsion injury to the left brachial plexus root (associated with upper-limb chronic neuropathic pain) were given electroacupuncture stimulation at bilateral Quchi (LI11), Hegu (LI04), Zusanli (ST36) and Yanglingquan (GB34). After electroacupuncture therapy, chronic neuropathic pain in the rats' upper limbs was significantly attenuated. Immunofluorescence staining showed that the expression of β-endorphins in the arcuate nucleus was significantly increased after therapy. Thus, experimental findings indicate that electroacupuncture can attenuate neuropathic pain after brachial plexus injury through upregulating β-endorphin expression.

The pursuit of high internal quantum efficiency (IQE) for green emission spectral regime is referred as “green gap” challenge. Now researchers place their hope on the InGaN-based materials to develop high-brightness green light-emitting diodes. However, IQE drops fast when emission wavelength of InGaN LED increases by changing growth temperature or well thickness. In this paper, a new wavelength-adjusting method is proposed and the optical properties of LED are investigated. By additional process of indium pre-deposition before InGaN well layer growth, the indium distribution along growth direction becomes more uniform, which leads to the increase of average indium content in InGaN well layer and results in a redshift of peak-wavelength. We also find that the IQE of LED with indium pre-deposition increases with the wavelength redshift. Such dependence is opposite to the IQE-wavelength behavior in conventional InGaN LEDs. The relations among the IQE, wavelength and the indium pre-deposition process are discussed.

The pursuit of high internal quantum efficiency (IQE) for green emission spectral regime is referred as "green gap" challenge. Now researchers place their hope on the InGaN-based materials to develop high-brightness green light-emitting diodes. However, IQE drops fast when emission wavelength of InGaN LED increases by changing growth temperature or well thickness. In this paper, a new wavelength-adjusting method is proposed and the optical properties of LED are investigated. By additional process of indium pre-deposition before InGaN well layer growth, the indium distribution along growth direction becomes more uniform, which leads to the increase of average indium content in InGaN well layer and results in a redshift of peak-wavelength. We also find that the IQE of LED with indium pre-deposition increases with the wavelength redshift. Such dependence is opposite to the IQE-wavelength behavior in conventional InGaN LEDs. The relations among the IQE, wavelength and the indium pre-deposition process are discussed.

A strained SiGe/Si superlattice structure has been grown on a patterned Si substrate and its photoluminescence has been studied. The patterned substrate is composed of pyramid-like structures. It is found that there are Ge-rich SiGe quantum wires (QWR) at the crossings of adjacent planes that form the pyramid-like structure. Photoluminescence of strained the SiGe layer grown on a planar substrate and a patterned substrate was compared. The total intensity of photoluminescence from the patterned substrate was 5.2 times larger than that from the planar substrates. The result is discussed and it is believed that this increase in photoluminescence is related to the observed QWRs. (C) 1999 Elsevier Science Ltd. All rights reserved.

A new method for growing a GaN initial layer on a GaAs(0 0 1) substrate is reported. The experiments show that the optimized growth condition for a smooth GaN initial layer is to grow a two monolayer thick layer at 600°C under As pressure. The pure cubic GaN films of 500 nm has been obtained on such an initial layer, the X-ray diffraction and photoluminescence show that the C–GaN film has a very high quality. There is no yellow or DA band emission of PL spectrum and the FWHM of the X-ray rocking curve is only 10 min.

By using a stacked structure, adding an SiO2 dielectric cavity and an Al mirror, and evaporating a SiO anti-reflecting layer on the back of the substrate, the peak detectivity D-(5.5,D-1000,D-1)* of an unbiased P+-GexSi1-x/p-Si heterojunction internal photoemission (HIP) infrared detector at 77 K has been improved to 1.1 X 10(10) cm Hz(1/2)/W, with a peak quantum efficiency of similar to 2.8% and a photoresponse range of 2-8 mu m. Its D-p* is of the same order of magnitude as that of the PtSi infrared detectors being used in practice. In addition, an improved electrode structure is used in order to improve the performance and reliability of the device. (C) 1998 Elsevier Science B.V. All rights reserved.

The self-organized In0.25Ga0.75As quantum dots (QDs) were grown by conventional molecular beam epitaxy (MBE) and migration-enhanced epitaxy (MEE) at 500 degrees C. The dot initiation by MEE was much earlier than that by MBE due to the enhanced atomic migration. However, atomic-force microscopy showed that the mean base length and height are almost the same for the 60 ML dots grown both by MEE and MBE. For the MBE growth the atoms in the wetting layer migrate and participate in forming the dots after the dot's initiation to reduce the strain-energy accumulated in the wetting layer before the dot's initiation. From the size of the dots with 30 and 60 ML deposition thickness, it is realized that there is a critical thickness over which further deposition will not only enlarge the dots but also thicken the wetting layer. The photoluminescence intensity of QDs grown by MEE is more than an order of magnitude higher than that of QDs grown by MBE. It indicates that some types of defects were produced during the process of the dots growth by MBE. (C) 1998 Elsevier Science B.V. All rights reserved.

CdTe films were grown on (211)A GaAs and (211)B GaAs substrates by molecular beam epitaxy in a wide range of growth temperature. X-ray double crystal rocking curves were used to analyze the quality and orientation of the epitaxial films. Our experiments prove that the growth temperature has a great effect on the quality and orientation of the epitaxial CdTe films: T-sub 280 degrees C, CdTe(211)parallel to GaAs(211)A. For (211)B GaAs, the orientation of CdTe changes at 295 degrees C. An explanation is given of this result by considering the lattice mismatch and interface energy.

CdTe has been grown on (211)A GaAs for the first time in the growth temperature range of 240–310 °C by molecular beam epitaxy. The quality and characteristics of the epitaxial film were studied by photoluminescence spectra, an x‐ray double crystal rocking curve, a Nomarski interference microscope, and etching. High quality CdTe films were obtained. For our best film the full width at half maximum of the x‐ray double crystal rocking curve was 126 arcsecond, and that of photoluminescence at 77 K was 8.9 meV. The epilayer was always (211)A CdTe with a tilted angle of about 2° around CdTe[011]∥GaAs[011] with respect to the substrate. A model of the initial growth stage of CdTe on (211)A GaAs is presented.

It is found that the SiGe alloy self-organizes into uniform quantum dots embedded in the silicon layer during the growth of strained SiGe/Si multilayers on a Si (001) substrate by molecular beam epitaxy. The energy of photoluminescence from the quantum dots is higher than the indirect band-gap of Si, and the luminescence of the quantum dots exceeds that of quantum well by three orders of magnitude. This can be attributed to an indirect-to-direct band-gap conversion in the SiGe dots.

CdTe films have been grown on (001) GaAs substrates by molecular beam epitaxy in a wide range of growth temperature. X‐ray double crystal rocking curve has been used to analyze the quality and orientation of the epitaxial films. Our experiments prove that the growth temperature has a great effect on the quality and orientation of the epitaxial CdTe films: Tsub

A new mechanism of light-to-electricity conversion that uses InGaN/GaN QWs with a p–n junction is reported. According to the well established light-to-electricity conversion theory, quantum wells (QWs) cannot be used in solar cells and photodetectors because the photogenerated carriers in QWs usually relax to ground energy levels, owing to quantum confinement, and cannot form a photocurrent. We observe directly that more than 95% of the photoexcited carriers escape from InGaN/GaN QWs to generate a photocurrent, indicating that the thermionic emission and tunneling processes proposed previously cannot explain carriers escaping from QWs. We show that photoexcited carriers can escape directly from the QWs when the device is under working conditions. Our finding challenges the current theory and demonstrates a new prospect for developing highly efficient solar cells and photodetectors.

The resonant excitation is used to generate photo-excited carriers in quantum wells to observe the process of the carriers transportation by comparing the photoluminescence results between quantum wells with and without a p—n junction. It is observed directly in experiment that most of the photo-excited carriers in quantum wells with a p—n junction escape from quantum wells and form photocurrent rather than relax to the ground state of the quantum wells. The photo absorption coefficient of multiple quantum wells is also enhanced by a p—n junction. The results pave a novel way for solar cells and photodetectors making use of low-dimensional structure.

Subjective quality evaluation is the basis of quality evaluation of stereoscopic images. As the lack of a public and diverse testing database currently, in this paper, a symmetric stereoscopic images database is built. And then the subjective quality of stereoscopic images is analyzed from two aspects, one is the effects of JPEG, JPEG2000, H.264. The other is the comparisons between symmetric and asymmetric stereoscopic images from Gaussian blurring, white Gaussian noise, JPEG and JPEG2000, respectively. The results show three compressions are quite different in the subjective quality of symmetric stereoscopic images at different bitrates, and the comparisons between symmetric and asymmetric stereoscopic images investigate the properties of binocular fusion, binocular suppression, and binocular summation.

In this paper, an objective assessment model based on three-component weighted structural similarity is presented for stereoscopic image. Since different distortions affect details of stereoscopic image differently, the image is classified into three kinds of regions including edge, smooth and texture regions so that different weights are associated to different regions to assess distorted stereoscopic image. The experimental results show that the assessment scores are consistent with subjective stereoscopic perception when stereoscopic image is degraded by blur, white noise, JPEG and JPEG 2000 process. Thus the objective assessment results can well reflect the image quality and stereoscopic perception.

The active photo-excited carrier has been identified in reverse biased quantum dot resonant tunneling diode (QDRTD) for light detection. The QD is embedded on the AlAs/GaAs/AlAs double barrier part of the material structure and is found with strong charge memory effect. The QD is charged with electrons in forward bias and the charge storage of QD is maintained well in reverse bias until the voltage of QD resonant tunneling peak. With this charge memory effect, the photo-excited holes are charged into QDs in forward bias and still influence the reverse bias behavior of QDRTD at dark. Compared to the illuminated QDRTD in reverse bias, the active photo-excited carrier of reverse biased QDRTD is unambiguously identified as photo-excited holes. The potential profile of QDRTD structure is also calculated and the potential near charged QDs is found greatly pushed up above GaAs E C . This may explain the trapping of photo-excited hole by QD for QDRTD in reverse bias.

A back-incident Si/sub 0.65/Ge/sub 0.35//Si multiple quantum-well resonant-cavity-enhanced photodetector operating near 1.3 /spl mu/m is demonstrated on a separation-by-implantation-oxygen substrate. The resonant cavity is composed of an electron-beam evaporated SiO/sub 2/-Si distributed Bragg reflector as a top mirror and the interface between the buried SiO/sub 2/ and the Si substrate as a bottom mirror. We have obtained the responsivity as high as 31 mA/W at 1.305 /spl mu/m and the full width at half maximum of 14 nm.

We report on a Si1-xGex/Si multiple quantum-well resonant-cavity-enhanced (RCE) photodetector with a silicon-on-oxide reflector as the bottom mirror operating near 1.3 mu m. The breakdown voltage of the photodetector is above 18 V and the dark current density at 5 V reverse bias is 12 pA/mu m(2). The RCE photodetector shows enhanced responsivity with a clear peak at 1.285 mu m and the peak responsivity is measured around 10.2 mA/W at a reverse bias of 5 V. The external quantum efficiency at 1.3 mu m is measured to be 3.5% under reverse bias of 16 V, which is enhanced three- to fourfold compared with that of a conventional p-i-n photodetector with a Ge content of 0.5 reported in 1995 by Huang [Appl. Phys. Lett. 67, 566 (1995)]. (C) 2000 American Institute of Physics. [S0003-6951(00)00628-8].

We report on a study of interfacial structure of GaN films grown on GaAs(001) substrates by plasma-assisted molecular beam epitaxy using x-ray grazing-angle specular reflection. We show that interfacial layers with electron densities differing from those of GaN and GaAs were formed upon deposition of GaN. It is also found that the interfacial structure of our systems depends strongly on the course of the initial layer deposition. The phase purity of the GaN films was examined by x-ray reciprocal space mapping. A simple kinetic growth model suggested by our results has been presented.

This paper presents the first report on the successful use of a ruling machine that forms planar grooves as a grating coupler on AlGaAs/GaAs MQW for a reflected optical bistality study. A low switch threshold of 5 microW/microm for the bistability of thermal origin has been observed. Using the same method, QW wire and QW box systems have been defined. Blue shifts of 8 and 26–30 meV of the photoluminescence upon changing the temperature from 14 to 200 K. have been obtained in QW wires and QW boxes, respectively, with different well widths and lateral sizes.