增量电位滴定模式在低浓度磺酸盐阴离子测定中的应用

在两相电位滴定中,采用增量模式和动态模式两种滴定剂添加方式测定了阴离子表面活性剂有效物浓度。实验表明,试样质量分数在0.3%～0.09%,阳离子滴定剂质量浓度为0.004mol/L,V(萃取剂水)∶V(无水乙醇)∶V(MIBK)=2∶1∶1时,标样的增量添加模式的准确度和精密度0.09%优于动态添加模式的0.29%,试样的增量添加模式的精密度0.68%高于动态模式的1.02%。

诱发电位地形图及临床应用

四、诱发电位地形图的临床应用 (一)视觉诱发电位地形图: 视觉诱发电位地形图就是将视觉刺激引起的大脑皮层各区的电位变化通过地形图仪用图像的形式反映出视觉诱发电位不同时相的空间电位分布图。它的刺激方式和条件与视觉诱发电位相同,刺激方式多采用单眼,双眼和半视野等形式。在一般情况下我们在做完单眼视诱发电位后即行双眼视诱发地形图。在特殊视觉功能下可加做半视野检查。

昆虫触角电位技术的研究进展

触角电位技术是直接检测昆虫对化学信号反应的电生理方法。通过介绍该技术的原理、触角电位仪基本结构和发展历程、实验注意事项及其局限性,旨在为研究昆虫电生理行为提供一个清晰的思路,对解决试验中遇到的问题有一定的帮助。

诱发电位地形图

第一节 视觉诱发电位地形图 一、视觉诱发电位地形图的概念 视觉诱发电位地形图（Visual evoked potential mapping）是视觉诱发电位曲线图经快速付立叶转换而成为的地形图。是研究被检查者在给予外界特定条件视觉的刺激下皮层电位的分布状态。

CV-6209阻断血小板活化因子引起的动作电位持续时间短缩

目的 :探讨血小板活化因子 (PAF)的作用及其机制。方法 :采用标准微电极技术观察PAF对豚鼠左心室乳头肌的电生理作用以及PAF受体拮抗剂CV 62 0 9对PAF诱发的电生理作用的影响。结果 :PAF明显缩短动作电位持续时间 ;PAF灌流前后 ,APD90 (90 %复极水平的动作电位时相 )分别为 14 4.0± 6.3ms和 12 0 .3± 5 .6ms(n =8,P <0 .0 1)。经CV 62 0 9(n =5 )灌流后 ,PAF诱发的APD90 短缩率为 5 .8%± 1.9% ,而对照组APD90 短缩率为 16.4%± 1.8% (P <0 .0 5 )。结论 :CV 62 0 9可阻断PAF引起的动作电位持续时间短缩 。

单侧肢体肌萎缩征的临床及肌电图分析

单侧肢体肌萎缩征又名青少年非进行性单侧肢体肌萎缩征,病因不明,多数学者认为本病是一种独立的神经——肌肉病患。国内目前未见有系统报道,而国外研究较多。从我们近年来临床观察发现,本病并非少见,因临床医师对本病缺乏足够的认识,常致漏诊或误诊。现将我院1985年～1992年门诊收治的21例患者的临床及肌电图检查结果报告如下。

Icon memory research under different time pressures and icon quantities based on event-related potential

In order to obtain related brain electrical components and neural bases of physiology assessment of icon elements in a digital human-computer interface the modified sample-delay matching task experimental paradigm is used under different time pressures 4 000 and 2 000 ms and different icon quantities three five and ten icons on icon memory based on event-related potential ERP technology.Experimental results demonstrate that P300 has significant volatility changes and the maximum amplitude around the middle line of the parietal area PZ and P200 has obvious volatility changes around the middle line of the frontal and central area FCZ during icon cognition.P300 and P200 amplitudes increase as tasks become more difficult.Thus P300 latency is positively correlated with task difficulty. ERP research on the characteristics of icon memory will be an important reference standard in guiding user neurocognitive behavior and physiology assessment on interface usability.

A High-Performance Silicon Electro-Optic Phase Modulator with a Triple MOS Capacitor

We propose and analyze a novel Si-based electro-optic modulator with an improved metal-oxide-semiconductor （MOS） capacitor configuration integrated into silicon-on-insulator （SOl）. Three gate-oxide layers embedded in the silicon waveguide constitute a triple MOS capacitor structure, which boosts the modulation efficiency compared with a single MOS capacitor. The simulation results demonstrate that the Vπ Lπ product is 2. 4V · cm. The rise time and fall time of the proposed device are calculated to be 80 and 40ps from the transient response curve, respectively,indicating a bandwidth of 8GHz. The phase shift efficiency and bandwidth can be enhanced by rib width scaling.

Dependent mechanism of Chinese prepositions processing in the brain:evidence from event-related potentials

Objective To compare the event-related potentials （ERPs） waves of verbs and prepositions in the brain. Methods We recorded ERPs in the brain while participants judged the legality of the collocation for verbs and ＂preposition＂. Results Both verbs and prepositions elicited a negativity at the frontal site in 230-330 ms and 350-500 ms window. No difference was seen in 230-330 ms and 350-500 ms window; In difference waves, a negativity was elicited in the left and fight hemisphere at about 270-400 ms and 470-600 ms window for both open and closed-class words. Conclusion These may demonstrate that prepositions in modem Chinese are probably not a separate class from verbs and that N280 may be not a specific component for only prepositions （or closed-class words）.

Establishment of continuous cooling transformation diagrams of aluminum alloys using in situ voltage measurement

An effective method was proposed to establish the continuous cooling transformation（CCT） diagrams of aluminum alloys using in situ voltage measurement.The voltage change of samples with predefined dimension was recorded under the constant current state during continuous cooling.Solutionizing time,together with starting and finishing temperatures of phase transformation of the alloy can be obtained from relationships of voltage vs time and temperature.A critical cooling rate without detectable phase transition during continuous cooling can be determined.Continuous cooling transformation diagrams of tested samples can be established conveniently based on these results.Microstructure observation and differential scanning calorimetry（DSC） testing were applied to verify the reliability of continuous cooling transformation diagram.

Design of a 2.5GHz Low Phase-Noise LC-VCO in 0.35μm SiGe BiCMOS

This paper introduces a 2.5GHz low phase-noise cross-coupled LC-VCO realized in 0.35μm SiGe BiCMOS technology. The conventional definition of a VCO operating regime is revised from a new perspective. Analysis shows the importance of inductance and bias current selection for oscillator phase noise optimization. Differences between CMOS and BJT VCO design strategy are then analyzed and the conclusions are summarized. In this implementation, bonding wires form the resonator to improve the phase noise performance. The VCO is then integrated with other components to form a PLL frequency synthesizer with a loop bandwidth of 30kHz. Measurement shows a phase noise of - 95dBc/Hz at 100kHz offset and - 116dBc/Hz at 1MHz offset from a 2.5GHz carrier. At a supply voltage of 3V, the VCO core consumes 8mA. To our knowledge,this is the first differential cross-coupled VCO in SiGe BiCMOS technology in China.

Design of 2.5GHz Low Phase Noise CMOS LC-VCO

A 2 5GHz fully integrated LC VCO is fabricated in a standard single poly 4 metal 0 35μm digital CMOS process,using a complementary cross coupled topology for lowering power dissipation and reducing the effect of 1/ f noise.An on chip LC filtering technique is used to lower the high frequency noise.Accumulation varactors are used to widen frequency tuning.The measured tuning range is 23 percent.A single hexadecagon symmetric on chip spiral is used with grounded shield pattern to reduce the chip area and maximize the quality factor.A phase noise of -118dBc/Hz at 1MHz offset is measured.The power dissipation is 4mA at V DD =3 3V.

A 2GHz Low Power Differentially Tuned CMOS Monolithic LC-VCO

A 2GHz differentially tuned CMOS monolithic LC-VCO is designed and fabricated in a 0.18μm CMOS process. The VCO has a 16.15% tuning range （from 1. 8998 to 2. 2335GHz） through a combination of analog and digital tuning techniques （4-bit binary switch-capacitor array）. The measured phase noise is - 118.17dBc/Hz at a 1MHz offset from a 2. 158GHz carrier. With the presented improved switch,the phase noise varies no more than 3dB at different digital control bits. The phase noise changes only by about 2dB in the tuning range because of the pn-junctions as the varactors. The VCO draws a current of about 2. lmA from a 1.8V power supply and works normally with a 1.5V power supply.

单独离子活度研究进展

本文论述了过去二十多年中对单独离子活度研究的重大进展。研究方向主要有两个。一是企图通过消除或估计相界面电位(液接电位)来实验测定;二是以离子溶液理论为指导,将电解质的平均活度系数合理地分解为单独离子的活度系数。

A wideband low-phase-noise LC VCO for DRM/DAB frequency synthesizer

The wideband CMOS voltage-controlled oscillator（VCO）with low phase noise and low power consumption is presented for a DRM/DAB（digital radio mondiale and digital audio broadcasting）frequency synthesizer.In order to obtain a wide band and a large tuning range,a parallel switched capacitor bank is added in the LC tank.The proposed VCO is implemented in SMIC 0.18-μm RF CMOS technology and the chip area is 750 μm×560 μm,including the test buffer circuit and the pads.Measured results show that the tuning range is 44.6%;i.e.,the frequency turning range is from 2.27 to 3.57 GHz.The measured phase noise is-122.22 dBc/Hz at a 1 MHz offset from the carrier.The maximum power consumption of the core part is 6.16 mW at a 1.8 V power supply.

Effects of acute aerobic exercise on response preparation in a Go/No Go Task in children with ADHD:An ERP study

Purpose： The purpose of this study was to investigate the impact of acute exercise on reaction time and response preparation during a Go/No Go Task in children with attention deficit hyperactivity disorder （ADHD）. Methods： Nineteen children with ADHD （aged between 8 and 12 years old） undertook a 30-min intervention that consisted of treadmill running or video-watching presented in a counterbalanced order on different days. A Go/No Go Task was administrated after exercise or video-watching. Results： The results indicated a shorter reaction time and smaller contingent negative variation （CNV） 2 amplitude following exercise relative to the video-watching. For event related potential （ERP） analyses, greater CNV l and CNV 2 amplitudes in response to No Go stimuli in com- parison to Go stimuli was observed in the video-watching session only. Conclusion： These findings suggest that acute exercise may benefit children with ADHD by developing appropriate response preparation, particularly in maintaining a stable motor preparatory set prior to performing the given task.

Influence of Heterojunction Position on SiGe HBTs with Graded BC Junctions

The influence of a heterojunction in the vicinity of a graded BC junction on the performance of npn SiGe HBTs is studied. SiGe HBTs differing only in heterojunction position in the vicinity of a graded BC junction are simulated by means of 2D Medici software for DC current gain and frequency characteristics. In addition, the simulated DC current gains and cut-off frequencies are compared at different collector-emitter bias voltages. Through the simulation results, both DC and HF device performance are found to be strongly impacted by degree of confinement of the neutral base in the SiGe layer, even in the absence of a conduction band barrier. This conclusion is of significance for designing and analyzing SiGe HBTs.

Numerical simulation on electrolyte flow field in 156 kA drained aluminum reduction cells

Based on the commercial CFD software CFX-4.3, two-phase flow of electrolyte in 156 kA drained aluminum reduction cells with a new structure was numerically simulated by multi-fluid model and k-ε turbulence model. The results show that the electrolyte flow in the drained cells is more even than in the conventional cells. Corresponding to center point feeding, the electrolyte flow in the drained cells is more advantageous to the release of anode gas, the dissolution and diffusion of alumina, and the gradient reduction of the electrolyte density and temperature. The average velocity of the electrolyte is 8.3 cm/s, and the maximum velocity is 59.5 cm/s. The average and maximum velocities of the gas are 23.2 cm/s and 61.1 cm/s, respectively. The cathode drained slope and anode cathode distance have certain effects on the electrolyte flow.

Effects of acute aerobic exercise on motor response inhibition:An ERP study using the stop-signal task

Purpose： The purpose of this study was to determine the effects of acute exercise on motor response inhibition using both behavioral and electrophysiological approaches. Methods： The P3 and N1 event-related potential （ERP） components were recorded while performing a stop-signal task in 21 college students following a moderately intense acute exercise bout for 30 min and a sedentary control session that involved reading. Results： Acute exercise induced a shorter stop signal response time （SSRT） as compared to control; however, the go response time （Go RT） remained unchanged. In examining the ERP data, acute exercise increased both P3 amplitude and latency but did not affect the N1 component. Conclusion： Acute exercise has a selective and beneficial effect on cognitive function, specifically affecting the motor response inhibition aspect of executive function. Furthermore, acute exercise predominately impacts later stages of information processing during motor response inhibition, which may lead to an increase in attentional resource allocation and confer the ability to successfully withhold a response to achieve motor response inhibition.

A Three-Stage Operational Amplifier for a Wide Range of Capacitive Loads

This paper presents a three-stage CMOS operational amplifier （opamp） that combines accuracy with stability for a wide range of capacitive loads. A so-called quenching capacitor is added to a multipath nested Miller compensation （MNMC） topology to obtain stability for a wide range of capacitive loads. Theoretical analysis and mathematical formulas are provided to prove the improvement in stability. A prototype of this frequency compen- sation scheme is implemented in a 0.7μm CMOS process. Measurement′s show that the amplifier can drive capaci- tive loads ranging from 100pF to 100/μF with a gain of 90dB and a minimum phase margin of 26°. The amplifier has a unity-gain bandwidth of 1MHz for a 100pF capacitive load. It employs a quenching capacitance of 18pF.