Photonic integrated technology for multi-wavelength laser emission

We summarized the design, fabrication challenges and important technologies for multi-wavelength laser transmitting photonic integration. Technologies discussed include multi-wavelength laser arrays, monolithic integration and modularizing coupling and packaging. Fabrication technique requirements have significantly declined with the rise of reconstruction-equivalent-chirp and second nanoimprint mask technologies. The monolithic integration problem between active and passive waveguides can be overcome with Butt-joint and InP array waveguide grating technologies. The dynamic characteristics of multi-factors will be simultaneously measured with multi-port analyzing modules. The performance of photonic integration chips is significantly improved with the autoecious factors compensation packaging technique.     

Serum levels of perfluorinated compounds in the general population in Shenzhen, China

Perfluorinated compounds (PFCs) have been detected in many environmental matrices, biota, and nonoccupationally exposed populations in China recently. However, little is known about the distribution and levels of various PFCs in the general population living in areas where there is PFC exposure. In the present study, the levels and prevalence of ten target PFCs were determined in 227 serum samples from a population of nonoccupationally exposed individuals in Shenzhen, China. Results indicated that human exposure to PFCs was prevalent in Shenzhen. Perfluorooctanoate (PFOA) was the dominant PFC contaminant in the serum samples, with a median concentration of 6.72 ng/mL, followed by perfluorooctane sulfonate (PFOS) with a median concentration of 2.07 ng/mL. Other PFCs were detected at much lower concentrations, with median concentrations ranging from 0.02 to 0.87 ng/mL. Statistically, no significant (P>0.05) gender differences were observed for any of the PFCs. Significant (P<0.01) positive correlations were found between age and serum concentrations of the target PFCs, except for perfluorobutane sulfonate (R = 0.16, P = 0.01), perfluorohexanoic acid (R = 0.08, P = 0.22), and perfluoroheptanoic acid (R = 0.11, P = 0.10). Based on the one-compartment pharmacokinetic model, the total daily intakes of PFOA and PFOS for the general population in Shenzhen were calculated as 0.63 and 0.20 ng/kg body weight/day, respectively.     

Rolling-induced microstructure change in Zr_(65)Al_(7.5)Ni_(10)Cu_(12.5)Ag_5 bulk metallic glass

The microstructures and free-volume evolutions of as-cast and pre-annealed Zr65Al7.5Ni10Cu12.5Ag5 bulk metallic glasses during rolling deformation have been investigated. No phase transformation is detected in the as-cast/rolled specimen. However,the structural stability of the glass against plastic deformation is worse after pre-annealing,indicated by nanocrystallization in preannealed/rolled specimens with large deformation degrees. Moreover,with increasing deformation degree,the free-volume content in a ...     

A comparison of optimization theories for energy conservation in heat exchanger groups

In general,thermal processes can be classified into two categories: heat-work conversion processes and heat transfer processes. Correspondingly,the optimization of thermal processes has to have two different criteria:the well known entropy generation minimization method and the recently proposed entransy dissipation maximization method. This study analyzes the thermal issues in a heat exchanger group,and optimizes the unit arrangements under different constraints based on a suitable optimization crite-rion. The result indicates that the principle of minimum entropy generation rate is valid for optimizing heat exchangers in a ther-modynamic cycle with given boundary temperatures. In contrast,the entransy dissipation maximization is more suitable in heat exchanger optimizations involving only heat transfer processes. Furthermore,the entropy generation rate induced by dumping used streams into ambient surroundings has to be taken into account,except for that originating from the hot and cold-ends of heat exchangers,when using the entropy generation minimization to optimize heat exchangers undergoing a thermodynamic cycle.     

Forced response of atmospheric oscillations during the last millennium simulated by a climate system model

Variations in global atmospheric oscillations during the last millennium are simulated using the climate system model FGOALS_gl. The model was driven by reconstructions of both natural forcing (solar variability and volcanic aerosol) and anthropogenic forcing (greenhouse gases and sulfate aerosol). The model results are compared against proxy reconstruction data. The reconstructed North Atlantic Oscillation (NAO) was out of phase with the Pacific Decadal Oscillation (PDO) in the last millennium. During the ...     

Progress in the research of GSH in cells

Glutathione (GSH), γ-Glu-Cys-Gly, is one of the most abundant small non-protein thiol molecules in mammalian tissues, particu- larly in the liver. Although glutathione is present in thiol-reduced (GSH) and disulfide oxidized (GSSG) forms, the predominant form is GSH and its content can exceed 10 mmol/L in liver cells. As an important intracellular reductant, GSH has many biological functions in cells. Its major function is as an anti-oxidant as it can protect proteins from oxidation by reversible posttranslational modification (glutathionylation) and decrease reactive oxygen species-mediated damage. However, it does have numerous other functions, including to chelate metal irons; enhance the absorption of iron, selenium and calcium; participate in lipid and insulin metabolism; regulate cellular events such as gene expression, DNA and protein synthesis, cell proliferation and apoptosis, redox-dependent signal transduction pathways, cytokine production and the immune response; and control protein glutathionylation. Therefore, GSH plays important roles in cell survival and health, and an imbalance in the GSH level can lead to many diseases. In this review, we provide an overview of the function of GSH in mammalian cells and discuss future research of GSH.     

Compact fiber-optic diode-laser sensor system for wide-dynamic-range relative humidity measurement

A compact fiber-optic diode-laser sensor system for measuring relative humidity is studied. In such a system, a distributed feedback laser lasing near 1877 nm is used as light source while a high-precision Pt resistance as temperature sensor, an accuracy of 0.1% relative-humidity can be achieved. The laser sensor system is able to lock to the absorption peak and calculate the density of water vapor without any additional reference measurements. Using programs built in to the microcontroller unit, the laser system can switch functions between direct measurement at high density and second-harmonic detection at low density. The system can switch between the two modes automatically and work in a wide dynamic range.     

基于时序植被指数的东北地区耕地生长季特征识别与应用研究

基于多时相遥感信息可以有效反映区域尺度上作物物候期特征的原理,利用1998—2009年期间的SPOT/VGT NDVI逐旬时间序列数据,采用TIMESAT软件集成的非对称高斯函数拟合方法对数据序列进行平滑重构处理,进而根据拟合曲线变化特征定义并提取了我国东北地区耕地生长季特征参数（包括生长季开始期、峰值期、结束期与生长...     

论思维的复杂系统模型暨新一代专家系统的设想

在复杂系统研究思想指导下,构建了基于神经元网络结构的复杂系统思维模型,提出以网络节点表示概念,以网络连接表示命题,以网络回路实现知识表达,以网络节点间的时空动力学激发实现演绎推理等思维活动的理论新框架,并以此为基础对新一代专家系统进行了设计。     

基于剩余寿命的劣化系统最优维修策略

考虑Gamma型劣化可替换系统的最优观测/替换策略问题,给出了基于剩余寿命的观测函数,得到期望单位时间维修费用最小化准则下的最优维修策略.相对于传统的非周期观测策略,该方法只需要一个比例风险系数参数来确定检测时间,从而降低了策略优化过程的复杂性.数值模拟表明在系统长期使用的单位时间维修费用上,基于平均剩余寿命的策略可以得到比一些基于状态的维修策略更优的结果.