Correlation of vascular endothelial growth factor to permeability of blood-brain barrier and brain edema during high-altitude exposure

BACKGROUND： Many studies have evaluated the role of vascular endothelial growth factor （VEGF） in traumatic brain edema and hemorrhagic brain edema. OBJECTIVE： To observe the effects of VEGF expression on permeability of the blood-brain barrier （BBB） during high-altitude and hypoxia exposure, and to investigate the correlation between VEGF expression and BBB permeability with regard to Evans blue staining and brain edema during high-altitude exposure. DESIGN, TIME AND SETTING： The randomized, controlled, animal study was performed at the Tanggula Etape, Central Laboratory of Chengdu Medical College, and Central Laboratory of General Hospital of Chengdu Military Area Command of Chinese PLA, China, from July 2003 to November 2004. MATERIALS： Quantitative RT-PCR kit （Sigma, USA）, VEGF ELISA kit （Biosource, USA）, and Evans blue （Jingchun, China） were acquired for this study. METHODS： A total of 180 Wistar rats were equally and randomly assigned to 15 groups： low-altitude （500 m）, middle-altitude （2 880 m）, high-altitude （4 200 m）, super-high-altitude （5 000 m）, 1,3, 5, 7, 9, 11, 13, 15, 17, 19, and 21 days of super high-altitude exposure. Wistar rats were exposed to various altitude gradients to establish a hypoxia model. MAIN OUTCOME MEASURES： Brain water content was calculated according to the wet-to-dry weight ratio. BBB permeability to Evans blue was determined by colorimetric method. VEGF mRNA and protein levels in brain tissues were detected using RT-PCR and double-antibody sandwich ELISA. RESULTS： Brain water content, BBB permeability to Evans blue, and VEGF mRNA and protein levels in brain tissues increased with increasing altitude and prolonged exposure to altitude. The greatest increase was determined on day 9 upon ascending 5 000 m. Simultaneously, VEGF expression positively correlated to BBB permeability of Evans blue and brain water content （r = 0.975, 0.917, P〈 0.01）. CONCLUSION： Increased VEGF protein and mRNA expression was responsible for increased BBB permeability, which may be an important mechanism underlying brain edema during high-altitude exposure.

High performance trench MOS barrier Schottky diode with high-k gate oxide

A novel trench MOS barrier Schottky diode（TMBS） device with a high-k material introduced into the gate insulator is reported, which is named high-k TMBS. By simulation with Medici, it is found that the high-k TMBS can have 19.8% lower leakage current while maintaining the same breakdown voltage and forward turn-on voltage compared with the conventional regular trench TMBS.

Fabrication of high temperature grating on thermal barrier coatings based on solute-solvent separation soft lithography

In this study, an etched-SiO-film grating fabrication technique based on solute-solvent separation soft lithography is developed. By using this new technique, high temperature grating with frequency of 600 lines/mm is successfully fabricated on the surface of thermal barrier coatings(TBCs). During the fabrication process, the microstructure and chemical compositions of ceramic coating before and after polishing is analyzed with a digital microscope and the energy dispersive X-ray spectroscope(EDS) in scanning electron microscope(SEM). And then the grating on TBCs is heated at the temperature ranging from 300℃ to 1000℃ for examining the high temperature resistance. In the practical application, the displacement and strain field around the crack on the ceramic surface are investigated with geometry phase analysis(GPA). The successful results verify that the etched-SiO-film grating has a good oxidation resistance and can be applied to high temperature deformation measurement of TBCs.

GaN As/InGaAs Superlattice Solar Cells with High N Content in the Barrier Grown by All Solid-State Molecular Beam Epitaxy

We demonstrate nearly i e V GaN0.03As0.97 /In0.09 Ga0.91As strain-compensated short-period superlattice solar cells by all solid-state molecular beam epitaxy. The optimal period thickness for the superlattice growth is achieved to realize high structural quality. Meanwhile, the annealing conditions are optimized to realize a pho- toluminescence （PL） at a low temperature. However, no PL signal is detected at room temperature, which could be reflected by a lower open-circuit voltage of the fabricated devices. The GaN0.03As0.97/In0.09Ga0.91As super- lattice solar cells show a reasonably-high short-circuit current density （Jsc） of over lOmA/cm2. Eurthermore, a concentration behavior is measured, which shows a linear relationship between Jsc and concentration ratios. The extrapolated ideality factor and saturated current density by the concentration action are in good agreement with that extracted by the dark case of the p-i-n diodes.

High-performance 4H-SiC junction barrier Schottky diodes with double resistive termination extensions

4H-SiC junction barrier Schottky （JBS） diodes with a high-temperature annealed resistive termination extension （HARTE） are designed, fabricated and characterized in this work. The differential specific on-state resistance of the device is as low as 3.64 mΩ·cm^2 with a total active area of 2.46× 10 ^-3 cm^2. Ti is the Schottky contact metal with a Schottky barrier height of 1.08 V and a low onset voltage of 0.7 V. The ideality factor is calculated to be 1.06. Al implantation annealing is performed at 1250 ℃ in Ar, while good reverse characteristics are achieved. The maximum breakdown voltage is 1000 V with a leakage current of 9× 10^-5 A on chip level. These experimental results show good consistence with the simulation results and demonstrate that high-performance 4H-SiC JBS diodes can be obtained based on the double HARTE structure.

Analytical model including the fringing-induced barrier lowering effect for a dual-material surrounding-gate MOSFET with a high-κ gate dielectric

By solving Poisson＇s equation in both semiconductor and gate insulator regions in the cylindrical coordinates, an analytical model for a dual-material surrounding-gate （DMSG） metal-oxide semiconductor field-effect transistor （MOSFET） with a high-k gate dielectric has been developed. Using the derived model, the influences of fringing-induced barrier lowering （FIBL） on surface potential, subthreshold current, DIBL, and subthreshold swing are investigated. It is found that for the same equivalent oxide thickness, the gate insulator with high-k dielectric degrades the short-channel performance of the DMSG MOSFET. The accuracy of the analytical model is verified by the good agreement of its results with that obtained from the ISE three-dimensional numerical device simulator.

The influence and explanation of fringing-induced barrier lowering on sub-100 nm MOSFETs with high-k gate dielectrics

The fringing-induced barrier lowering（FIBL） effect of sub-100 nm MOSFETs with high-k gate dielectrics is investigated using a two-dimensional device simulator.An equivalent capacitance theory is proposed to explain the physics mechanism of the FIBL effect.The FIBL effect is enhanced and the short channel performance is degraded with increasing capacitance.Based on equivalent capacitance theory,the influences of channel length,junction depth,gate/lightly doped drain（LDD） overlap length,spacer material and spacer width on FIBL is thoroughly investigated.A stack gate dielectric is presented to suppress the FIBL effect.

Enhancement-mode AlGaN/GaN high electronic mobility transistors with thin barrier

An enhancement-mode （E-mode） A1GaN/GaN high electron mobility transistor （HEMTs） was fabricated with 15-nm A1GaN barrier layer. E-mode operation was achieved by using fluorine plasma treatment and post-gate rapid thermal annealing. The thin barrier depletion-HEMTs with a threshold voltage typically around -1.7 V, which is higher than that of the 22-nm barrier depletion-mode HEMTs （-3.5 V）. Therefore, the thin barrier is emerging as an excellent candidate to realize the enhancement-mode operation. With 0.6-tim gate length, the devices treated by fluorine plasma for 150-W RF power at 150 s exhibited a threshold voltage of 1.3 V. The maximum drain current and maximum transconductance are 300 mA/mm, and 177 mS/ram, respectively. Compared with the 22-nm barrier E-mode devices, VT of the thin barrier HEMTs is much more stable under the gate step-stress,

曙光5000高性能计算机Barrier网络的设计

为优化Barrier操作的性能,提高大规模并行计算应用在曙光5000系统中的执行效率,文中提出了一种基于硬件的Barrier加速设计.该设计是采用树形Barrier算法,通过增强曙光5000互联网络交换芯片的功能,实现低延迟、可扩展、高可靠和可管理的Barrier网络.该网络支持并发16个Barrier操作,可在Fat-Tree拓扑环境下实现较低的Barrier操作延迟.相比已有实现,是更适合Fat-Tree拓扑的设计方案.理想情况下,1024个节点的同步操作在1.7μs内完成.根据Barrier操作归约和分发过程的特点,分别采用请求应答和超时催促两种机制,为Barrier操作的可靠性提供保障.以该设计实现的Barrier网络原型系统已通过FPGA验证.

软土地基上水利枢纽基础处理施工技术

对于水利枢纽工程而言,基础处理的科学性、合理性直接关系到工程的安全运行和经济效益。软土地基因其低承载力、高压缩性和流变特性,为水利枢纽工程的设计与施工带来诸多挑战,这些地质条件要求采用特定的工程技术以确保结构的稳定性和功能的可靠性。从搅拌桩的布置与施工、混凝土的浇筑与固化过程以及施工后的质量控制与验收等方面阐述了软土地基上水利枢纽基础处理的施工技术,最后对地基加固成效进行了评估,确保加固措施达到预期效果。

Effects of a flexible net barrier on the dynamic behaviours and interception of debris flows in mountainous areas

Flexible net barriers are a new type of effective mitigation measure against debris flows in valleys and can affect the kinematic energy and mass of debris flows. Here, ten flume tests were performed to study the dynamic behaviours of debris flows with differences in volumes, concentrations(solid volume fraction), and travel distances after interception by a uniform flexible net barrier. A high-speed camera was used to monitor the whole test process, and their dynamic behaviours were recorded. A preliminary computational framework on energy conversion is proposed according to the deposition mechanisms and outflow of debris flow under the effects of the flexible net barrier. The experimental results show that the dynamic interaction process between a debris flow and the flexible net barrier can be divided into two stages:(a) the two-phase impact of the leading edge of the debris flow with the net and(b) collision and friction between the body of the debris flow and intercepted debris material. The approach velocity of a debris flow decreases sharply(a maximum of 63%) after the interception by the net barrier, and the mass ratio of the debris material being intercepted and the kinetic energy ratio of the debris material being absorbed by the net barrier are close due to the limited interception efficiency of the flexible net barrier, which is believed to be related to the flexibility. The energy ratio of outflow is relative small despite the large permeability of the flexible net barrier.

Coherent gradient sensing method for measuring thermal stress field of thermal barrier coating structures

Coherent gradient sensing （CGS） method can be used to measure the slope of a reflective surface, and has the merits of full-field, non-contact, and real-time measurement. In this study, the thermal stress field of thermal barrier coating （TBC） structures is measured by CGS method. Two kinds of powders were sprayed onto Ni-based alloy using a plasma spraying method to obtain two groups of film-substrate specimens. The specimens were then heated with an oxy-acetylene flame. The resulting thermal mismatch between the film and substrate led to out-of-plane deformation of the specimen. The deformation was measured by the reflective CGS method and the thermal stress field of the structure was obtained through calibration with the help of finite element analysis. Both the experiment and numerical results showed that the thermal stress field of TBC structures can be successfully measured by CGS method.

Arrangement of High-standard Basic Farmland Construction Based on Village-region Cultivated Land Quality Uniformity

As an important constitute of land consolidation, high-standard basic farmland construction is an important means to protect the quantity, quality and ecological environment of cultivated land. Its target not only lies in the increase of cultivated land quantity, but also the improvement of cultivated land quality, agricultural production conditions and ecosystem environments. In the present study, the quality evaluation method and construction arrangement of cultivated land were explored to facilitate the process of decision-making and implementation for high-standard basic farmland construction(HSBFC) with administrative village as the unit. Taking the land comprehensive improvement project area in Quzhou County, Handan City, Hebei Province as a case study, the whole process of the study comprised of three steps: 1) establishment of the evaluation model of cultivated land quality uniformity based on regional optimum cultivated land quality, and construction of the uniformity evaluation index system from the aspects of soil fertility quality, engineering quality, spatial quality and eco-environment quality, according to the new concept of cultivated land quality; 2) calculation of cultivated land quality uniformity by grading indicators, assigning scores and weighting sums, exploring the local homogenization characteristics of regional cultivated land quality through spatial autocorrelation analysis, and analyzing the constraints and transformative potential of barrier factors; 3) arrangement of HSBFC according to the principle of concentration, continuity and priority to the easy operation. The results revealed that the value of farmland quality uniformity for the administrative villages in the study area was between 7.76 and 21.96, and there was a difference between various administrative villages. The regional spatial autocorrelation patterns included High-High(HH), Low-Low(LL), High-Low(HL) and Low-High(LH). These indicate that regional cultivated land quality has local homogenization characteristics. The most restrictive factors in the study area were the medium and low transformation difficulty indexes, including soil organic matter content, farmland shelterbelt network density, field regularity and scale of the field. In addition, there were also high transformation difficulty indicators in some areas, such as sectional configuration. The project area was divided into four partitions: major construction area, secondary construction area, general construction area, and conditional construction area. The cultivated land area of each subarea was 1538.85 ha, 1224.27 ha, 555.93 ha, and 1666.63 ha, respectively. This comprised of 30.87%, 24.56%, 11.15% and 33.42% of the total project area, respectively. The evaluation model and index system could satisfy the evaluation of farmland quality and diagnosis of obstacle factors to facilitate the subsequent construction decision. The present study provides reference for the practice of regional HSBFC, and a new feasible idea and method for related studies.

Formation and behavior of thermal barrier coatings on nickel-base superalloys

Plasma sprayed thermal barrier coatings (TBCs) have been used to extend the life of combustors. Electron beam physical vapor deposited (EB PVD) ceramic coating has been developed for more demanding rotating as well as stationary turbine components. Here 3 kW RF magnetron sputtering equipment was used to gain zirconia ceramic coatings on hollow turbine blades and vanes, which had been deposited NiCrAlY by cathodic arc deposition. NiCrAlY coating surface was treated by shot peening; the effects of shot peening on the residual stress are presented. The results show that RF sputtered TBCs are columnar ceramics, strongly bonded to metal substrates. NiCrAlY bond coat is made of β, γ ′ and Cr phases, ZrO 2 ceramic layer consists of t ′ and c phases. No degradation occurs to RF ceramic coatings after 100 h high temperature oxidation at 1 150 ℃ and 500 thermal cycles at 1 150 ℃ for 2 min, air cooling.

Upregulated inflammatory associated factors and blood-retinal barrier changes in the retina of type 2diabetes mellitus model

AIM： To examine the expression of high mobility group box-1（HMGB-1） and intercellular adhesion molecule-1（ICAM-1） in the retina and the hippocampal tissues; and further to evaluate the association of these two molecules with the alterations of blood-retinal barrier（BRB） and blood-brain barrier（BBB） in a rat model of type 2 diabetes.METHODS： The type-2 diabetes mellitus（DM） model was established with a high-fat and high-glucose diet combined with streptozotocin（STZ）. Sixteen weeks after DM induction, morphological changes of retina and hippocampus were observed with hematoxylin-eosin staining, and alternations of BRB and BBB permeability were measured using Evans blue method. Levels of HMGB-1 and ICAM-1 in retina and hippocampus were detected by Western blot. Serum HMGB-1 levels were determined by enzyme-linked immunosorbent assay（ELISA）.RESULTS： A significantly higher serum fasting blood glucose level in DM rats was observed 2wk after STZ injection（P 〈0.01）. The serum levels of fasting insulin,Insulin resistance homeostatic model assessment（IRHOMA）,total cholesterol（TC）, total triglycerides（TG） and low density lipoprotein cholesterol（LDL-C） in the DM rats significantly higher than those in the controls（all P 〈0.01）.HMGB-1（0.96±0.03, P 〈0.01） and ICAM-1（0.76±0.12, P 〈0.05） levels in the retina in the DM rats were significantly higher than those in the controls. HMGB-1（0.83±0.13, P 〈0.01） and ICAM-1（1.15 ±0.08, P 〈0.01） levels in the hippocampal tissues in the DM rats were alsosignificantly higher than those in the controls. Sixteen weeks after induction of DM, the BRB permeability to albumin-bound Evans blue dye in the DM rats was significantly higher than that in the controls（P 〈0.01）.However, there was no difference of BBB permeability between the DM rats and controls. When compared to the controls, hematoxylin and eosin staining showed obvious irregularities in the DM rats.CONCLUSION： BRB permeability increases significantly in rats with type-2 DM, which may be associated with the up-regulated retinal expression of HMGB-1 and ICAM-1.

Filament Discharge Phenomena in Fingerprint Acquisition by Dielectric Barrier Discharge

In this paper, the dielectric barrier discharge fingerprint acquisition technique is introduced. The filament discharge phenomena were observed in the process of fingerprint acquisition. The filament discharge reduced the quality of fingerprint images. Obviously, it was necessary to eliminate streamer discharges in order to get good fingerprint images. The streamer discharge was considered to be the cause of the filament discharge in the experiment. The relationship between the critical electric field and the discharge gap was calculated with the Raether＇s model of streamer discharge. The calculated results and our experiment proved that it would be difficult for the streamer discharge to occur when the discharge gap was narrow. With a narrow discharge gap, the discharge was homogeneous, and the fingerprint images were clear and large in area. The images obtained in the experiment are very suitable for fingerprint identification as they contain more information.

高阻隔包装薄膜发展现状及产业化建议

分析了高阻隔包装薄膜在包装市场的应用,对聚偏氯乙烯(PVDC)、乙烯–乙烯醇共聚物(EVOH)、聚酰胺(PA)、聚萘二甲酸乙二醇酯(PEN)以及热塑性聚乙烯醇(TPVA)等阻隔材料进行了介绍,总结了高阻隔包装薄膜的制备方式及未来发展趋势,提出高阻隔包装薄膜产业化的发展建议。

A threshold voltage analytical model for high-k gate dielectric MOSFETs with fully overlapped lightly doped drain structures

We investigate the influence of voltage drop across the lightly doped drain（LDD） region and the built-in potential on MOSFETs,and develop a threshold voltage model for high-k gate dielectric MOSFETs with fully overlapped LDD structures by solving the two-dimensional Poisson＇s equation in the silicon and gate dielectric layers.The model can predict the fringing-induced barrier lowering effect and the short channel effect.It is also valid for non-LDD MOSFETs.Based on this model,the relationship between threshold voltage roll-off and three parameters,channel length,drain voltage and gate dielectric permittivity,is investigated.Compared with the non-LDD MOSFET,the LDD MOSFET depends slightly on channel length,drain voltage,and gate dielectric permittivity.The model is verified at the end of the paper.