基于交流阻抗和数值积分方法测定腐蚀反应电阻

提出了基于交流阻抗和数值积分原理的二点频率法。通过数值积分计算出腐蚀体系交流阻抗的突部和虚部,求解方程获得腐蚀反应电阻,进而求得腐蚀反应速度。该方法测量时间短,精度高。根据这一改进方法,建立了以TP801B单板计算机与TP801 1232A/D模数转换板及接口电路组成的腐蚀速度测量系统。通过对等效电路及实际体系的测量,并同SOLARTRON1250频响仪测量结果进行比较,证明了该方法的可靠性。由于整个过程仅由单板机控制,设备规模小,造价低,在腐蚀监控领域具有应用价值。

不同pH值对Au/CaM膜结合Ca^(2+)的电化学行为研究

采用交流阻抗的方法,在包含1 mmol/L Fe(CN)63-/4-的0.15 mol/L的NaCl溶液中,研究了Au/CaM膜在不同的酸碱环境下结合Ca2+的电化学行为.结果表明:在pH为6.5的环境下Au/CaM膜结合Ca2+的能力要比在pH为4.5环境下的强.

不锈钢化学镀Ni-Mo-P沉积速率的研究

研究了硫酸镍、柠檬酸钠、钼酸钠及pH值对不锈钢化学镀Ni-Mo-P沉积速率的影响。观察了化学镀Ni-Mo-P合金镀层的微观形貌,并对比了化学镀Ni-Mo-P合金镀层与化学镀Ni-P合金镀层的电化学反应电阻。通过沉积速率的研究,确定了化学镀Ni-Mo-P合金镀层的最佳配方及操作条件。实验结果表明:采用最佳配方及操作条件制备的化学镀Ni-Mo-P合金镀层表面呈现细致颗粒状结构,电化学反应电阻是化学镀Ni-P合金镀层的8.32倍,较好地保护了不锈钢基体。

化学镀镍钴磷合金的研究

通过正交试验对钢铁基体表面化学镀镍钴磷合金配方进行了选择,并对选择出的配方进行了性能测试。结果表明:化学镀镍钴磷合金镀层较致密,无明显缺陷,表面呈现有微裂纹的膜层状结构,镀层含钴48.72%(质量分数),晶相结构为晶态,化学镀镍钴磷镀层的电化学反应电阻与化学镀镍磷层相比提高了26%,化学镀镍钴磷合金的耐腐蚀性优于化学镀镍磷合金。

金属离子竞争结合钙调素的电化学行为研究

为了探讨金属离子与Ca^(2+)对钙调素(CaM)的竞争结合作用,在pH值为6.5含2mmol/L[Fe(CN)6]3-/4-的0.15 mol/L的NaCl溶液中,用交流阻抗法研究了金属离子如Ca^(2+),Cd^(2+),Al^(3+),Fe^(3+)结合及竞争结合钙调素的电化学行为。结果表明:金属离子与CaM的结合能力可以通过溶液中[Fe(CN)_6]^(3-/4-)在钙调素自组装膜修饰金电极上的电化学反应电阻的变化来判断,Ca^(2+),Cd^(2+)和Al ^(3+)都能与CaM结合,Fe^(3+)不能与CaM结合,且Ca^(2+)与CaM结合能力要比Al 3+强;Ca^(2+)在CaM上的结合位点与Cd^(2+)相同,与Al^(3+)不同。交流阻抗法为研究金属离子与CaM的竞争结合行为提供了一个新方法。

氯化钾镀锌添加剂的电化学性能

对BH 51氯化钾镀锌添加剂及其主要成分的极化性能、微分电容、整平性、反应电阻等进行了初步研究 ,结果表明 ,氯化钾镀锌添加剂可明显加大阴极极化 ,对镀层具有整平性。

EIS studies the effect of Zinc to Al-Zn alloy used for cathodic protection in 3% NaCl solution

Electrochemical impendence spectroscopy （EIS） is applied to investigate the dissolution behavior of Al-Zn alloys in 3% NaCl solution at different polarization potentials. A new reaction model is proposed, and the activation mechanism of zinc in Al-Zn alloys is achieved. There are three intermediates in the dissolution process： Znad^＋, Znad^2＋ and Alad^＋, ,of which only Zni can activate Al-Zn alloys. Most Znnd^＋ is produced by β-phase,and the alloys with 2. 3% - 3. 8% （wt） Zn dissolve rapidly. The Al-Zn alloys of heart-shaped EIS are active in 3% NaCl solution, thus EIS characteristic can be used to distinguish the activa-tion of Al-Zn alloys.

反应堆铂电阻测温仪表精密校准技术研究

设计了一种新的数控电阻网络结构。此结构能够降低由于继电器接触电阻不稳定特性的影响,实现高精度可变电阻输出,达到反应堆铂电阻测温仪表的精度等级要求。分析了在采用二进制电阻权重序列的情况下,由于电阻的初始误差导致的失配误差,并提出了失配误差的计算公式和不失配条件。新电阻结构具有高精度和高稳定性的特点,能够用于反应堆铂电阻测温仪表的设计、测试和校准工作。

RESEARCH ON MEMBRANE BIOREACTOR TREATING DOMESTIC WASTEWATER AND RELATED MECHANISMS

Experiments on treatment of domestic wastewater by membrane bioreactors were carried out.The results showed that this process could produce good quality effluent with low COD,turbidity and total count of bacteria.With intermittent operation and continuous aeration,the membrane flux was kept steady.The mechanisms of removing COD through membrane,the structure of membrane and filtration resistance were also discussed.

Abnormality of Magnetic Behavior and Resistivity of La_(0.7-x)Dy_x Sr_(0.3)MnO_3 (0.00≤x≤0.30)System at Low Temperature

By measuring M-T curves, ρ-T curves and MR-T curves of the samples under different temperatures, the influence of Dy doping （0.00 ≤ x ≤0.30） on the magnetic and electric properties of La0.7-xDyxSr0.3MnO3 has been studied. The experimental results show that, with the increase of the Dy content, the system undergoes a transition from long range ferromagnetic order to the cluster-spin glass state and further to antiferromagnetic order. For the samples with x=0.20 and 0.30, their magnetic behaviors are abnormal at low temperature, and their resistivities at low temperature have a minimum value. These peculiar phenomena not only come from the lattice effect induced by doping, but also from extra magnetic coupling induced by doping.

面针镇痛及其作用机制探讨

一、当人体某一部分发生病变时，往往会在相应的区域或穴位处出现压痛点，电阻降低或伴有形态和色泽变化。根据这些反应，可以对躯体或内脏疾病的定位起辅助诊断作用。应用电阻铡定仪，对121个病人合计242病例进行面部腧穴低电阻的测定工作，结果表明；符合率为60．3%(即低电阻反应与患者的主诉和临床诊断相一致的)。在面部24个腧穴中，出现反应点的有17个穴位。

Analysis and design of resistance-wire heater in MOCVD reactor

Metal organic chemical vapor deposition(MOCVD) is a key equipment in the manufacturing of semiconductor optoelectronic devices and microwave devices in industry. Heating system is a vital part of MOCVD. Specific heating device and thermal control technology are needed for each new reactor design. By using resistance-wire heating MOCVD reaction chamber model, thermal analysis and structure optimization of the reactor were developed from the vertical position and the distance between coils of the resistance-wire heater. It is indicated that, within a certain range, the average temperature of the graphite susceptor varies linearly with the vertical distance of heater to susceptor, and with the changed distances between the coils; furthermore, single resistance-wire heater should be placed loosely in the internal and tightly in the external. The modulate accuracy of the temperature field approximately equals the change of the average temperature corresponding to the change of the coil position.

Structural, Magnetic, and Electrical Properties of Al3＋ Substituted CuZn-ferrites

NanocrystallineCuo5Zno5Fe2-xAlxO2（x=0.0,0.1,0.2,0.3,0.45 and 0.5） ferrite materials were synthesized using standard solid state reaction technique. The effects of Al3＋ contents on the structural, electrical, and magnetic properties were investigated. Single phase cubic spinel structure was revealed by X-ray diffraction analysis. The crystallite size was evaluated considering the most intense diffraction peak （311） using Scherrer formula. Lattice constant decreased, whereas porosity increased with the increase in Al3＋ concentration. The value of saturation magnetization decreased with increasing aluminum contents. Temperature dependent value of direct current electrical resistivity has been determined. It is observed that the substitution of Al3＋ has significant impact on the dielectric constant, tangent of dielectric loss angle and dielectric loss factor. The variation in dielectric properties was attributed to space charge polarization.

Formation and growth of Cu-Al IMCs and their effect on electrical property of electroplated Cu/Al laminar composites

Cu/Al laminar composite was prepared by dipping Zn layer and then electroplating Cu thick layer on pure Al sheet.During annealing the Cu/Al composites at temperature from 473 to 673 K, the Cu/Al interfacial diffusion and reaction and itskinetics and also the electrical resistivity of the composites were studied. The results show that no Cu?Al IMC layer is observable asthe composites are annealed at 473 K for time till 360 h, indicating that the Zn intermediate layer can effectively suppress the Cu/Alinterfacial diffusion. However, as the composites are annealed at 573 K and above, Zn atoms in the Zn layer dissolve into the Culayer. Tri-layered reaction product of CuAl2/CuAl/Cu9Al4 then forms from the Al side to the Cu side. The IMC layer follows thediffusion-controlled growth kinetics. Electrical resistivity of the Cu/Al composites increases with the increase of the annealingtemperature and time.

Magnetic iron oxide nanoparticles carrying PTEN gene to reverse cisplatin-resistance of A549/CDDP cell lines

To evaluate the feasibility of using magnetic iron oxide nanoparticle as wild PTEN gene carrier for transfection in vitro to reverse cisplatin-resistance of A549/CDDP cells, A549/CDDP cells were transfected with the wild PTEN gene expression plasmid (pGFP-PTEN) by magnetic iron nanoparticle and lipo2000. The transfection efficiency was detected by fluorescence microscope and flow cytometer. The expression levels of PTEN mRNA and protein were detected by reverse transcription polymerase chain reaction (RT-PCR) and immunocytochemistry analysis. The effect of PTEN transfection on cell cycle enhances the sensitivity of A549/CDDP to cisplatin and nanoparticle-mediated transfection has a higher efficiency than that of the liposome-mediated group. The apoptosis level was up-regulated in PTEN transfection group. The magnetic iron oxide nanoparticle could be used as one of the ideal gene carriers for PTEN gene delivery in vitro. PTEN can be an effective target for reversing cisplatin-resistance in lung cancer.

Hierarchical Manganese Oxide/Carbon Nanocomposites for Supercapacitor Electrodes

MnO2/carbon nanocomposites with hierarchical pore structure and controllable MnO2 loading have been synthesized using a self-limiting growth method. This was achieved by the redox reactions of KMnO4 with sacrificed carbon substrates that contain hierarchical pores. The unique pore structure allows the synthesis of nanocomposites with tunable MnO2 loading up to 83 wt.%. The specific capacitance of the nanocomposites increased with the MnO2 loading; the conductivity measured by electrochemical impedance spectroscopy, on the other hand, decreased with increasing MnO2 loading. Optimization of the MnO2 loading resulted in nanocomposites with high specific capacitance and excellent rate capability. This work provides important fundamental understanding which will facilitate the design and fabrication of high-performance supercapacitor materials for a large variety of applications.

Spontaneously producing syngas from MFC-MEC coupling system based on biocompatible bifunctional metal-free electrocatalyst

The preparation of high-value fuels and chemicals through the electrochemical carbon dioxide reduction reaction(CDRR)is of great significance to the virtuous cycle of carbon dioxide.However,due to the high overpotential involved in this reaction,high power consumption and high-cost noble-metal-based catalysts are required for driving this process.Herein,the electrochemical CDRR was achieved on biocompatible metal-free nitrogen,phosphorus co-doped carbon-based materials(NP-C)in the microbial fuel cell-microbial electrolysis cell(MFC-MEC)coupling system.As the bioelectrochemistry in MFC supplied power to drive the electrocatalysis in MEC,syngas was spontaneously produced from this coupling system without external energy input.With the NP-C materials as the excellent bifunctional electrocatalyst for the CDRR and oxygen reduction reaction(ORR),the current density of the MEC reached−0.52 mA cm^−2,and the Faradaic efficiencies(FEs)of CO and H2 were 60%and 40%,respectively,at a load resistance of 10Ω.Moreover,the CO/H2 product ratio can be changed by adjusting the load resistance,which will widely meet various demand of syngas usage in further reactions.This study provides a spontaneous and tunable production of syngas in biogas digesters via a electrochemical strategy.

Alternaria toxin-induced resistance against rose aphids and olfactory response of aphids to toxin-induced volatiles of rose plants

The search for active toxins for managing weeds or plant diseases is believed to be a promising avenue of investigation. However, the effects of Alternaria toxins on insects have just begun to be investigated. Bioactivities of toxins from four strains of Altemaria alternata on Rosa chinensis and rose aphid Macrosiphum rosivorum were tested in the present study. At a concentration of 50.0 pg/ml, the crude extract （toxin） of strain 7484 was found not to be harmful to rose plants with excised leaf-puncture method （P≥0.079）, and rose plants showed enhanced resistance to rose aphids when this Altemaria toxin was sprayed on the plants （P≤0.001）. However, this toxin caused no detrimental effects on aphids in insecticidal bioassay at a concentration of 10.0 to 160.0 μg/ml （P≥0.096）. Therefore, the Alternaria toxin had significantly induced the resistance of rose plants against rose aphids, demonstrating that the resistance mechanism triggered by the Altemaria toxin in the rose plant may also be used by the plant to defend itself against insects. Further bioassays aimed to discover the olfactory responses of aphids to the toxin-induced volatiles of host plants. The aphids were significantly more attracted to both volatiles emitted and collected from control rose plants than to both volatiles emitted and collected from the toxin-treated rose plants （P≤0.014）. This result showed that the toxin-induced resistance related to the volatile changes of host plants.

Theoretical investigation on tunneling magnetoresistance in ferromagnetic/anti-ferromagnetic core/shell system

Based on Monte Carlo simulations,the effect of structural configuration on the hysteresis behavior and tunneling magnetoresistance(TMR) of composite nanoparticles with ferromagnetic(FM) core/anti-ferromagnetic(AFM) shell is investigated.The simulated results indicate that the coercive field(H c) of composites increases with the decreasing ratio of core-radius(r core) to shell-radius(r shell).When the ratio of r shell to r core is approaching 4:3,H c decreases with increasing AFM thickness.In addition,TMR is found to increase with the decreasing ratio of r core to r shell,resulting from the enhancement of resistance changes in disordered AFM shell.