Silicon-based microelectrode arrays for stimulation and signal recording of in vitro cultured neurons

Microelectrode arrays (MEAs) for stimulation and signal recording of in vitro cultured neurons are presented.Each MEA is composed of 60 independent electrodes with 59 working ones and one reference one.These electrodes are divided into 30 pairs.Through each pair of electrodes,four independent states can be realized to define the accessing modes of neurons cultured on the surface of the electrodes.A total MEA covers an area of 10 mm×10 mm.MEAs are fabricated in a silicon-based semiconductor process.An implemented MEA is bonded on a specially designed printed-circuit-board (PCB) and surrounded by a culture chamber.An impedance measurement has been made to verify the electrical characteristics of MEAs.The surface was modified to enhance the biocompatibility.A series of PC12 cells culture experiments validates the effectiveness of the modification.An extracellular signal recording experiment with acetylcholine (Ach) as a stimulant has been carried out,and the results show the feasibility of MEAs for extracellular action potential recording.Extracellular electrical stimulation and recording experiments have been carried out too.They indicate that MEAs can be used for extracellular stimulation,recording,simultaneous stimulation and recording,and isolation of PC12 cells network cultured in vitro.     

柳钢高炉炉况失常处理方法及特点

总结了柳钢高炉近年来多次出现的炉况失常及其处理过程的经验教训，提出了在处理失常炉况过程中减少反复、快速恢复的措施。     

Bifurcation and chaos of the bladed overhang rotor system with squeeze film dampers

To study the nonlinear dynamic behavior of the bladed overhang rotor system with squeeze film damper (SFD), a blade-overhang rotor-SFD model is formulated using the lumped mass method and the Lagrange approach. The cavitated short bearing model is employed to describe the nonlinear oil force of the SFD. To reduce the scale of the nonlinear coupling system, a set of orthogonal transformations is employed to decouple the one nodal diameter equations of blades, which are coupled with the dy- namical equations ...     

建筑评价系统与建筑发展迹线浅析

建筑是生活的容器。建筑的功能、技术和艺术三维属性为其意义的载体，建立科学的建筑评价系统对于建筑师的创作和建筑乃至社会的发展均有着重的作用。在建筑三维属性空间中进行半定量化的比较静态分析，并以之探索建筑发展的规律，这不仅能使人们更好地认识建筑，而且有利于深化对于人类自身的认识。     

Diode-pumped doubly Q-switched mode-locked YVO4/Nd:YVO4/KTP green laser with AO and GaAs saturable absorber

By using both acousto-optic modulator and GaAs saturable absorber, a diode-pumped Q-switched and mode-locked(QML) YVO₄/Nd:YVO₄/KTP green laser is presented. The experimental results show that the doubly QML YVO₄/Nd:YVO₄/KTP green laser has good stability and nearly 100% modulation depth. The average output power and the pulse width of the Q-switched envelope have been measured. The mode-locked pulse inside the Q-switched envelope has a repetition rate of 137 MHz and its pulse width is estimated to be about 280 ps. By using a hyperbolic secant square function and considering the Gaussian distribution of the intracavity photon density, the coupled equations for diode-pumped dual-loss-modulated QML green laser is given and the numerical solutions of the equations are in good agreement with the experimental results.     

Power source research at USC: Development of advanced electrocatalysts for polymer electrolyte membrane fuel cells

This paper provides an overview on the development of advanced fuel cell cathode catalysts at University of South Carolina (USC) with the emphasis on the stability of non-precious metal and Pt alloy catalysts. Nitrogen-modified carbon composite (NMCC) catalysts were developed for the oxygen reduction reaction (ORR) through the pyrolysis of cobalt (iron)-nitrogen chelate followed by the treatment combination of pyrolysis, acid leaching, and re-pyrolysis. A promising stability was observed for 1050 h fuel cell operation under current density of 200 mA cm⁻² as evidenced by a potential decay rate as low as 40 μV h⁻¹. The performance degradation mechanism of the NMCC-based fuel cell is discussed. Pt and PtPd hybrid catalysts are developed that use a NMCC, which is itself active for the ORR, instead of a conventional carbon black support. The stability test at 1 A cm⁻² indicated that the Pt/NMCC hybrid catalyst (new Pt-Co/C) is more stable than the conventional Pt-Co/C without the Co leaching out. The PEM fuel cell accelerated stress test (AST) for supports and catalysts demonstrated that their stability changes in the order: Pt₃Pd₁/NMCC hybrid catalyst > Pt/NMCC hybrid catalyst > conventional Pt/C catalyst. Moreover, the hybrid catalysts exhibit higher mass activity than the Pt/C catalysts.     

A Latency-Aware Multiple Data Replicas Placement Strategy for Fog Computing

Journal of Signal Processing Systems - With the rapid increase of the number of IoT devices, transmitting big amount of data from these devices to data centers which are far away will cause...     

C语言在水泥配料计算中的运用

水泥配料计算是工艺设计和正常生产的常用计算。由于牵涉到非线性方程的求解，用手工计算需反复试凑，难以得到最优解。而各种简化计算方法也不容易为大多数人掌握。本程序用C语言作为编程语言，采用试探法求解，只须输入原料组成，大概配比及率值，几分钟即可得到最优解。     

An improved dynamic model for angular contact ball bearings under constant preload

High-speed spindles are typically installed with angular contact ball bearings. This research has established a dynamic model for angular contact ball bearings under constant preload. By analyzing the constant preload mechanism, and the gyroscopic and centripetal forces, a dynamic non-linear model for angular contact ball bearings was proposed using Hertz contact theory. The model was solved by numerical iteration to obtain the dynamic parameters of an angular contact ball bearing which included: the dynamic normal contact force and contact angle, the maximum compressive stress and axial displacement, the contact pattern, stiffnesses, etc. To validate the model, a test device was designed which was equipped with a constant preloaded bearing group. By measuring the relative displacement of the bearings’ inner and outer rings under different conditions, the accuracy of the model was proved. This modeling method provided a theoretical basis for calculating bearing thermal characteristics, fatigue life, and an optimized radius of curvature of the bearing ring channel.