单片集成的增强型和耗尽型pHEMT技术

随着射频/微波器件的快速发展及其应用领域的日益扩大,基于半导体单片集成技术的多种器件集成工艺不断发展。研究了一种采用AlGaAs-InGaAs的砷化镓化合物衬底。琥珀酸湿法蚀刻工艺对器件电性能影响较小。将耗尽型和增强型赝配高电子迁移率晶体管(pseudomorphic High-Electron-Mobility Transistor, pHEMT)器件集成于同一芯片半导体工艺技术。结果表明,增强型晶体管Y型栅极的线宽为0.25 m,开启电压为0.3 V;耗尽型晶体管栅极的线宽为0.5 m,开启电压为-0.8 V,实现了在同一芯片上集成从负到正的栅极电压分布,为设计者提供了更为宽广的设计平台。这种集成技术可以应用于低噪声放大器、线性天线开关、滤波器以及功率控制装置等领域。     

Enhanced dielectric and piezoelectric properties in Na0.5Bi4.5Ti4O15 ceramics with Pr-doping

The bismuth layer-structured Na_0.5Bi_4.5-xPr_xTi₄O₁₅ (x?=?0, 0.1, 0.2, 0.3, 0.4, and 0.5) (NBT-xPr³⁺) ceramics were fabricated using the traditional solid reaction process. The effect of different Pr³⁺ contents on dielectric, ferroelectric and piezoelectric properties of Na_0.5Bi_4.5Ti₄O₁₅ ceramics were investigated. The grain size of Pr³⁺-doping ceramics was found to be smaller than that of pure one, the maximum dielectric constant and Curie temperature T_c gradually decreased with increasing Pr³⁺ contents, and the dielectric loss decreased at high temperature by Pr³⁺-doping. Moreover, the activation energy (E_a), resistivity (Z’), remanent polarization (2P_r) and piezoelectric constant (d₃₃) increased by Pr³⁺-doping. The NBT-xPr³⁺ ceramics with x?=?0.3 achieved the optimal properties with the maximum dielectric constant of 1109.18, minimum loss of 0.00822 (250?kHz), E_a of 1.122?eV, Z’ of 7.9?kΩ?cm (725 ºC), d₃₃ of 18 pC/N, 2P_r of 12.04 μC/cm². The enhancement was due to the addition of Pr³⁺ which suppressed the decreasing of resistivity at high temperature and made it possible for NBT-xPr³⁺ ceramics to be poled in perpendicular direction, implying that it is a great improvement for Na_0.5Bi_4.5Ti₄O₁₅ ceramics in electrical properties.     

低信噪比直序扩频导航信号的自适应捕获算法研究

为解决低信噪比下直序扩频导航信号的捕获,提出了一种自适应捕获算法.该算法基于相干相关模型及FFT,提高了后测信噪比、缩短了捕获时间.对GPS C/A信号的捕获进行了仿真实验,结果表明此算法明显优于非相干相关算法,可提供约2 dB左右处理增益,捕获灵敏度达到-175 dBW.该算法可以运用于其它类似的卫星定位与直序扩频测距信号的伪码精确跟踪及相位测量中.     

Usefulness of Plasma YKL-40 in Management of Community-Acquired Pneumonia Severity in Patients

Plasma YKL-40 level has been reported as playing a significant role in community-acquired pneumonia (CAP). However, the correlation between plasma level of YKL-40 and the severity of CAP has not been reported. This study identifies the relationship between plasma level changes of the YKL-40 gene in adult patients hospitalized with CAP. The ELISA was used to measure the plasma YKL-40 level from 61 adult CAP patients before and after antibiotic treatment and from 60 healthy controls. The plasma YKL-40 levels were significantly increased in patients with CAP compared to normal controls. Moreover, the plasma concentration of YKL-40 correlated with the severity of CAP based on the pneumonia severity index (PSI) score (r = 0.630, p < 0.001), the CURB-65 (confusion, uremia, respiratory rate, BP, age 65 years) score (r = 0.640, p < 0.001), the Acute Physiology And Chronic Health Evaluation II (APACHE II) score (r = 0.539, p < 0.001) and length of hospital stay (r = 0.321, p = 0.011), respectively. In conclusion, plasma YKL-40 may play a role in the diagnosis and clinical assessment of CAP severity, which could potentially guide the development of treatment strategies.     

Analysis of Heat Transfer Behaviour of the Conduction Cold Plate System

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Determination of a Vapor Compression Refrigeration System Refrigerant Charge

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Cellular uptake of protein-bound magnetic nanoparticles in pulsed magnetic field

A method for fast delivery of proteins conjugated to superparamagnetic iron oxide nanoparticles (SPION) into mammalian cells by applying a strong magnetic field in pulses was proposed. Firstly, SPION were prepared from an alkaline solution of divalent and trivalent iron ions and covalently bound with protein through the activation of N-ethyl-N'-(3-dimethylaminopropyl) carbodiimide (EDC). After fluorescently labelling, the protein-nanoparticle conjugate was mixed with mammalian cell line and exposed to a pulsed magnetic field for short durations of few milliseconds. Results suggested that superparamagnetic nanoparticles were able to carry proteins into living cells immediately. Cellular internalization of the fluorescently labelled protein-nanoparticle conjugate was proved by the observation of cell fluorescence in a fluorescent microscopy, as well as cell analysis by a flow cytometer. We found that the cellular uptake was accomplished dominantly by the process of bombardment of magnetic nanoparticles.     

Cross-Talk of Toll-Like Receptor 5 and Mu-Opioid Receptor Attenuates Chronic Constriction Injury-Induced Mechanical Hyperalgesia through a Protein Kinase C Alpha-Dependent Signaling

Recently, Toll-like receptors (TLRs), a family of pattern recognition receptors, are reported as potential modulators for neuropathic pain; however, the desired mechanism is still unexplained. Here, we operated on the sciatic nerve to establish a pre-clinical rodent model of chronic constriction injury (CCI) in Sprague-Dawley rats, which were assigned into CCI and Decompression groups randomly. In Decompression group, the rats were performed with nerve decompression at post-operative week 4. Mechanical hyperalgesia and mechanical allodynia were obviously attenuated after a month. Toll-like receptor 5 (TLR5)-immunoreactive (ir) expression increased in dorsal horn, particularly in the inner part of lamina II. Additionally, substance P (SP) and isolectin B4 (IB4)-ir expressions, rather than calcitonin-gene-related peptide (CGRP)-ir expression, increased in their distinct laminae. Double immunofluorescence proved that increased TLR5-ir expression was co-expressed mainly with IB4-ir expression. Through an intrathecal administration with FLA-ST Ultrapure (a TLR5 agonist, purified flagellin from Salmonella Typhimurium, only the CCI-induced mechanical hyperalgesia was attenuated dose-dependently. Moreover, we confirmed that mu-opioid receptor (MOR) and phospho-protein kinase Cα (pPKCα)-ir expressions but not phospho-protein kinase A RII (pPKA RII)-ir expression, increased in lamina II, where they mostly co-expressed with IB4-ir expression. Go 6976, a potent protein kinase C inhibitor, effectively reversed the FLA-ST Ultrapure- or DAMGO-mediated attenuated trend towards mechanical hyperalgesia by an intrathecal administration in CCI rats. In summary, our current findings suggest that nerve decompression improves CCI-induced mechanical hyperalgesia that might be through the cross-talk of TLR5 and MOR in a PKCα-dependent manner, which opens a novel opportunity for the development of analgesic therapeutics in neuropathic pain.