葡聚糖中超顺磁氧化铁复合纳米粒子制备影响因素及表征

利用化学共沉积法在改性葡聚糖体系下制备了以超顺磁性纳米氧化铁为核心，外包葡聚糖的壳核结构复合粒子．对制备过程控制因素进行了详细的研究，实验结果表明：利用改性葡聚糖为表面活性剂，碱源快速滴加，合理的控制反应时间，温度可形成小核的超顺磁性纳米氧化铁-葡聚糖复合纳米粒子．在优化的实验条件下，得到核心的平均粒径5nm，总体的平均粒径为7．8nm，并利用XRD、TEM和GLS等手段对其结构，形态和粒径分布进行了表征．     

Flow direction characteristics in the vicinity of the spark plug in an S. I. Engine

The flame speed may be decomposed into the burning speed and the flame transport speed. The flame transport speed is affected considerably by the flow direction, variation rate of flow direction, and flow speed in the combustion chamber. Especially, the flow direction and the variation rate of flow direction at the spark plug location during the ignition period have an important effect on the ignition process and the early flame propagation process. We measured the flow direction component and the variation rate of flow direction with a hot wire probe at the spark plug location. It was shown that the representative flow direction of ignition period is the right-vertical direction of crank shaft and it was used to investigate the variation rate of flow direction.     

Haptic Perception,Mechanics, and Material Technologies for Virtual Reality

Emerging virtual and augmented reality technologies can transform human activities in myriad domains, lending tangible, embodied form to digital data, services, and information. Haptic technologies will play a critical role in enabling human to touch and interact with the contents of these virtual environments. The immense variety of skilled manual tasks that humans perform in real environments are only possible through the coordination of touch sensation, perception, and movement that together comprise the haptic modality. Consequently, many research groups are vigorously investigating haptic technologies for virtual reality. A longstanding research goal in this area has been to create haptic interfaces that allow their users to touch and feel plausibly realistic virtual objects. In this progress report, the perspective on this unresolved research challenge is shared, guided by the observation that no technologies can even approximately match the capabilities of the human sense of touch. Factors that have it challenging to engineer haptic technologies for virtual reality, including the extraordinary spatial and temporal tactile acuity of the skin, and the complex interplay between continuum mechanics, haptic perception, and interaction are identified. The perspective on how these challenges may be overcome through convergent research on haptic perception, mechanics, electronics, and material technologies is presented.     

某游泳馆空调节能设计、运行能耗分析

游泳馆建筑温湿度要求与其他公共建筑不同,能耗较大,在舒适度和节能之间选择一个合适的点,并据此合理地确定其空调方式,对游泳馆建筑节能至关重要。目前国内关于游泳馆等方面的设计规范、标准尚不完善,成功的案例不多,通过总结南京市某游泳馆投入使用后1年的监测数据,从实践的角度探讨游泳馆建筑空调节能设计思路。     

A Novel Vertical Directional Coupler Switch with Switching Operation‐Induced,Extinction Ratio‐Adjusted,and Extinction Ratio‐Enhanced Sections

We propose a novel very short (< 300 μm) vertical directional coupler switch with high extinction ratios larger than 30 dB. The device consists of a switching operation induced section (SOIS), an extinction ratio adjusted section (ERAS), and an extinction ratio enhanced section (ERES). These are achieved by changing the refractive index of one core. The switching operation is induced by changing the refractive index of one core in the SOIS. The improvement of extinction ratios larger than 30 dB for both the cross and bar states is made by controlling the asymmetry of the refractive indices of both cores in the ERES. Through the ERAS, different extinction ratios between the cross and bar states at the end of the SOIS are changed to the same value. For this reason, the optimum asymmetry of the refractive indices of the cores for the maximum extinction ratios and the lengths of ERES are the same for cross and bar states. Design guidelines for high extinction ratios with large tolerances are presented.     

Pathophysiological Reconstruction of a Tissue-Specific Multiple-Organ On-A-Chip for Type 2 Diabetes Emulation using 3D Cell Printing

Type 2 diabetes mellitus (T2D), a chronic complex disease with high prevalence, causes severe damage to various organs. T2D has many etiologies that have not been fully elucidated. Although various models have been created to understand T2D, reconstructing the tissue-specific microenvironment and complications of T2D remain difficult. Therefore, a dynamic multiple-organ on-a-chip that mimics T2D in a hyperglycemic environment and visceral adipose tissue (vAT) using 3D cell printing with decellularized extracellular matrix (dECM) bioinks is developed. This chip composed of separate compartments for the pancreas, adipose tissue, and liver, closely related to T2D, and a retinal compartment is added to confirm T2D complications. Furthermore, the pathological features of T2D are clearly revealed in the chip with vAT-derived dECM bioink in a hyperglycemic environment. These pathological features caused cellular dysfunctions of the retinal compartment. Moreover, treated T2D medications on the chip showed clinically identical efficacy. The chip is suitable for recapitulating the key features of T2D and is a promising platform for drug testing and T2D complication research.     

用"镜像法"处理高功率激光系统中非共轴光路的鬼点问题

高功率激光系统中鬼光束对元件安全造成威胁,并导致主光束质量变坏,故鬼光束会聚点的位置和鬼光束会聚光斑光强的定量分析,对高功率激光系统安全运行非常重要。提出了用“镜像法”分析高功率激光系统中非共轴光路鬼点的方法。即将光路在各反射镜处“镜像”,由“镜像”得到等效光学系统,对等效系统进行鬼点分析后,再将鬼点“镜像”回原非共轴光学系统。结果表明,非共轴光学系统的鬼点情况,可由其“镜像”等效系统决定。     

EPON最新标准与技术进展(本期优秀论文)

介绍了EPON标准和技术的最新进展情况,重点分析了三种EPON的技术发展方向:10GEPON标准进展情况及主要技术特点、2G EPON标准进展及主要技术特点以及WDM EPON的技术特点.通过对EPON技术发展的分析,得出今后FTTX发展的趋势.     

Wheat-germ aspartate transcarbamoylase: revised purification, stability and re-evaluation of regulatory kinetics in terms of the Monod-Wyman-Changeux model

A revised and simplified purification scheme for aspartate transcarbamoylase (ATCase) from wheat-germ is reported, with an eightfold increase in scale (yielding approximately 10 mg of the pure protein from 4 kg of wheat-germ), and improved characteristics of stability and regulatory kinetics. The ATCase obtained is greater than 96% pure, as judged by polyacrylamide gel electrophoresis. The long-term stability (i.e. on a time-scale of several hours to weeks) of the activity of the purified enzyme, under various storage conditions, was investigated. At 4 degreesC and pH 7.5, stability was found to be strongly dependent on protein concentration (increased stability at high concentration), buffer concentration (decreased stability at high buffer concentration) and the inclusion of glycerol (increased stability with increasing glycerol concentration). The enzyme is routinely stored at 4 degreesC, in 0. 05 m Tris/HCl buffer containing 25% glycerol and at high protein concentration (approximately 1 mg.mL-1, or 10 microm in trimers). Under these conditions, the half-life of the enzyme activity is greater than 300 days. Over the time-scale of kinetic experiments (up to 20 min), the diluted activity (at around 1 nm of ATCase, in the presence of ligands) is completely stable. The specific activity remains constant in the range 0.1-10 nm, in the absence and presence of ligands, showing that dissociation of the trimeric enzyme into its subunits is negligible. Steady-state kinetics were examined using the enzyme at a concentration of 1.3 nm. Initial-rate curves for both allosteric ligands, carbamoylphosphate (CP) and uridine 5'-monophosphate (UMP), showed pronounced sigmoidicity, each in the presence of the other. In the absence of UMP, initial-rate curves for CP are hyperbolic. The initial rate data fit reasonably well to a trimeric Monod-Wyman-Changeux model, suggesting a two-state conformational mechanism, greatly favouring the active (R) state when both ligands are absent, in which the R-state binds CP exclusively (dissociation constant = 23.2 microm), and the T-state binds UMP exclusively (dissociation constant = 0.49 microm). This regulatory behaviour was found to be quite stable, and was indistinguishable from that of the enzyme in a freshly made crude extract, even after storage of the pure sample for 5 months. This enzyme preparation is therefore free of the anomalous allosteric kinetics produced by a previous purification scheme, in which the affinity for UMP was markedly reduced, CP rate curves showed no sigmoidicity, while UMP rate curves had sigmoidicity exaggerated by a low maximum.     

Modeling, control, and design ofinput-series-output-parallel-connected converter for high-speed-trainpower system

In this paper, a charge control with an input voltage feedforward is proposed for an input-series-output-parallel-connected converter configuration for the high-speed-train power system application. This control scheme accomplishes the output current sharing. For the output-parallel-connected modules as well as the input voltage sharing for the input-series-connected modules for all operating conditions including the transients. It also offers the robustness for the input voltage sharing control according to the component value mismatches among the modules. This configuration enables the usage of a MOSFET for a high-voltage system allowing a higher switching frequency for a lighter system weight and smaller size. The performance of the proposed scheme is verified through the experimental results