Two-dimensional imaging biosensor for the monitoring of lactate released from brain slices

Real-time monitoring of lactate release from brain slices has been studied with an optical two-dimensional (2D) imaging biosensor. The 2D biosensor is prepared by direct immobilization of lactate dehydrogenase (LDH) molecules onto a flat silica glass surface through a covalent binding mechanism. The biosensor is able to spatially differentiate lactate concentration variations with conventional optical microscopic spatial resolution. This biosensor has the capability to effectively detect lactate down to a concentration of 100 nM. The 2D biosensor responds uniformly with 2.5% RSD from pixel to pixel. With a 100 ms response time, this 2D biosensor has the capability of monitoring simultaneously many cells in one image. We have studied the impact of KCI on lactate release from brain slices. Clear differences have been observed in lactate release for different regions of the tissue. The real-time determination of the newly released lactate from the mouse brain slices clearly demonstrates the feasibility of monitoring lactate release from living specimens. The 2D biosensor will enable us to study cellular communications and possibly other biological processes that require simultaneous temporal and spatial resolution.     

V2O5 nanofibre sheet actuators

Vanadium oxides, such as V2O5, are promising for lithium-ion batteries, catalysis, electrochromic devices and sensors. Vanadium oxides were proposed more than a decade ago for another redox-dependent application: the direct conversion of electrical energy to mechanical energy in actuators (artificial muscles). Although related conducting polymer and carbon nanotube actuators have been demonstrated, electromechanical actuators based on vanadium oxides have not be realized. V2O5 nanofibres and nanotubes provide the potential advantages of low-cost synthesis by sol-gel routes and high charging capacity and long cycle life. Here, we demonstrate electromechanical actuation for obtained high modulus V2O5 sheets comprising entangled V2O5 nanofibres. The high surface area of these V2O5 sheets facilitates electrochemical charge injection and intercalation that causes the electromechanical actuation. We show that the V2O5 sheets provide high Young's modulus, high actuator-generated stress, and high actuator stroke at low applied voltage.     

Optimal variable step-size LMS model and algorithm with independence assumption

To solve the contradiction between convergence rate and steady-state error in least mean square (LMS) algorithm, basing on independence assumption, this paper proposes and proves the optimal step-size theorem from the view of minimizing mean squared error (MSE). The theorem reveals the one-to-one mapping between the optimal step-size and MSE. Following the theorem, optimal variable step-size LMS (OVS-LMS) model, describing the theoretical bound of the convergence rate of LMS algorithm, is constructed. Then we discuss the selection of initial optimal step-size and updating of optimal step-size at the time of unknown system changing. At last an optimal step-size LMS algorithm is proposed and tested in various environments. Simulation results show the proposed algorithm is very close to the theoretical bound.     

静重式力标准机"逆程"现象的影响及消除

本文用详实的数据说明了静重式力标准机的"逆程"现象及对传感器检测结果的影响,介绍了电液伺服技术解决"逆程"现象的几个关键技术问题,肯定了电液伺服技术是消除"逆程"现象的一个行之有效的途径.     

Spatial distribution of single-photon and two-photon fluorescence light in scattering media: Monte Carlo simulation

Three-dimensional fluorescence spatial distributions under single-photon and two-photon excitation within a turbid medium are studied with Monte Carlo simulation. It is demonstrated that two-photon excitation has an advantage of producing much less fluorescence light outside the focal region compared with single-photon excitation. With the increase of the concentration of scattering particles in a turbid medium, the position of the maximum fluorescence intensity point shifts from the geometric focal region toward the medium surface. Further studies show that the optical sectioning property of two-photon fluorescence microscopy is degraded in thick turbid media or when the numerical aperture of an objective becomes low.     

Preparation of DyPt2 Films by Using Magneto Controlled Sputtering and Phase Transformation of Dy/Pt Alloy Films

DyPt2 films were prepared by alternate deposition thin Dy and Pt layers on glass substrates by DC magneto controlled sputtering method. The XRD data indicated that for as-deposited Dy/Pt films, and the periodic layered structures along thickness direction were evidenced with low angle X-ray scattering. With increasing annealing temperature, the compounds of DyPt, DyPt2 and DyPt3 were formed successively at temperature ranging from 300 to 400℃. It was found that the composition reaction DyPt DyPt3→2DyPt2 took place at 500℃. After annealing at 500℃ for 1h, the compounds DyPt and DyPt3 transformed completely into the DyPt2 compound.     

关于顶点链编码的图像区域表示和填充算法

图像区域的表示和显示是图像处理和图像分析、计算机制图和计算机图形学中的重要研究课题.以顶点链编码为基础,提出一种以顶点链编码来表示二值图像的方法,完成了对于图像区域的简单表示.同时着重提出了一种将用以表示二值图像的顶点链编码转化为原二值图像的算法.该算法对表示二值图像区域的顶点链编码点进行记录处理,配对被记录的顶点链编码点,然后运用水平扫描线来填充图像区域,从而将原图像根据顶点链编码完全恢复出来.     

冰蓄冷式中央空调在工程中的应用分析

以燕莎商城和凯宾斯基酒店的冰蓄冷空调工程为基础，阐述冰蓄冷空调对于平衡华北电网负荷、移峰填谷能够起到积极的作用。通过分析机房内合理配置的冰蓄冷系统设备，满足建筑物最舒适的空调要求，并结合北京市电价政策，分析冰蓄冷空调在节约运行费用方面的收益。     

化学镀镍对Ti粉吸气性能的影响

采用低温碱性化学镀方法制备镍包覆钛复合细粉，利用XRD，SEM，EDS和吸气性能测试台对样品的相结构、表面形貌、表面成分和吸气性能进行分析和表征。结果表明：表面镍层以结晶态包覆于Ti表面，镀层均匀，镀层中的Ni对H2具有催化解离作用，促进了Ti的吸氢速率，在较低温度450℃激活时，镍包覆钛复合细粉的吸氢性能较纯Ti粉有了明显的提高。     

Magnetic Properties and Intergranular Action in Bonded Hybrid Magnets

Magnetic properties and intergranular action in bonded hybrid magnets,based on NdFeB and strontium ferrite powders were investigated.The long-range magnetostatic interaction and short-range exchange coupling interaction existed simultaneously in bonded hybrid magnets,and neither of them could be neglected.Some magnetic property parameters of hybrid magnets could be approximately obtained by adding the hysteresis loops of two magnets pro rata.