The Measurement of Membrane Potential and NO3 Activity in Root Cells Using Ion-Selective Microelectrodes

Remobilisation of nitrate in plants, especially in vacuole of plant, is mostly related to the qua- lity of agricultural products and the high nitrogen use efficiency in plants. Ion-selective microelectrodes offer a non-destructive and non-interruptive method to measure NO 3 gradients and electric potential differences across both the plasma membrane and tonoplast. Thus, a double-barrelled microelectrode backfilled with a membrane sensor for NO 3 embedded in poly vinyl chloride (PVC) can record the NO 3 activity in cytoplasm and vacuole of a cell. This paper presented how to make this kind of microelectrode and how to do the intracellular measurements on intact plants. Our result showed that nitrate activity was about 2.7 mmol L 1 in cytoplasm while 70 mmol L 1 in vacuole, which implicated that vacuole was a pool of nitrate in plants.

Direct Determination of Potassium-Sodium Activity Ratio in Soil Suspension with Two Ion-Selective Electrodes

A K+-selective electrode and a Na+-selective electrode were used to construct a measuring cell without liquid-junction for the determination of the ion activity ratio of K+ to Na+ in soil suspensions. The measured cell potential was not affected by the total electrolyte concentration when the total cation concentration was 10-1-10-3 mol L-1 and the concentration ratio CK+ / CNa+. was 10:1 to 1:50. When the concentration ratios were equal to 1and the total electrolyte concentrations were 10-2 and 10-3 mol L-1, the ion activity ratio measurement would not be affected by pH in the pH range of 3.5 to 11.5 and 4.4 to 11 respectively. Ions other than H+ have no remarkable influence on the measurement. The ion activity ratio of K+ to Na+ measured directly in soil suspension agree well with those in centrifuged supernant solution. The relative deviation was within 4%. From the measured ion activity ratio, the difference of the bonding energies of K+ and Na+ ions was calculated.

Preparation of CeO_2 Nanoparticles and Its Application to Ion-selective Electrodes Based on Acetyl Cellulose

CeO2 nanoparticles with an average diameter of about 30 nm were prepared by sol-gel method at lower temperature. The gel, transformed from the aqueous solution of metal nitrate and citric acid, can be combusted completely at lower temperature. The redox behavior and the crystallization process of the dried gel were studied by thermogravimetric analysis and infrared spectroscopy. The synthesized powders were characterized by X-ray powder diffraction and transmission electron microscopy. In addition, rare earth elements ion-selective electrodes based on acetyl cellulose were prepared using ultra fine cerium oxide powders.

Construction and Application of a PVC Membrane Enoxacin Ion-selective Electrode Based on a Needle-shaped Inner Reference Electrode

A PVC membrane enoxacin ion-selective electrode based on a needle-shaped inner reference electrode was prepared. A Ag/AgCl wire was used as the substrate of this electrode. It was previously coated with a thin sheet of urea-formaldehyde resin containing Cl - ions to form a needle-shaped inner reference electrode, then the inner reference electrode was coated with a thin sheet of a PVC membrane containing an enoxacin tetraphenylborate ion-pair complex. The influences of various ion-pair complexes, concentrations of the active components in the membrane and the plasticizers on the performance of the electrode were studied by orthogonal design. The linear response range of the electrode was 7.9×10 -5 -1.0×10 -2 mol/L. The detection limit was 2.0×10 -5 mol/L. The slope was 30.4 mV/decade(25 ℃). The electrode can be used for the potentiometric determination of enoxacin tablets directly. The average recovery was 100.4%, and the RSD was 0.9%. The results agreed with those determined by the method in Chinese Pharmacopoeia.

Highly Efficient Power Conversion from Salinity Gradients with Ion-Selective Polymeric Nanopores

A polymeric nanopore membrane with selective ionic transport has been proposed as a potential device to convert the chemical potential energy in salinity gradients to electrical power. However, its energy conversion efficiency and power density are often limited due to the challenge in reliably controlling the size of the nanopores with the conventional chemical etching method. Here we report that without chemical etching, polyimide （PI） membranes irradiated with GeV heavy ions have negatively charged nanopores, showing nearly perfect selectivity for cations over anions, and they can generate electrical power from salinity gradients. We further demonstrate that the power generation efficiency of the PI membrane approaches the theoretical limit, and the maximum power density reaches 130m W/m2 with a modified etching method, outperforming the previous energy conversion device that was made of polymeric nanopore membranes.

DEVELOPMENT OF DOUBLE-BARRELED CALCIUM ION-SELECTIVE MICROELECTRODE

A new PVC matrix membrane double-barreled calcium ion-selective microelectrode based on liquid ion exchanger has been designed and constructed.The tip diameter of about 2.5μm as well as lower selectivity coefficients for K+,Na and Mg2+are adequate for in-tracellular measurements of Ca activities.The inner wall of the selective channel was made to be hydrophobic by treatment withalkyl-alcohols.By means of this microelectrode some physiologicalphenomena related to Ca2+activities have been studied,and Caconcentrations in clinical microsamples have also been determined.

Potentiometric Urea Biosensor Based on Ion-Selective Electrode by Different Immobilization Procedures

Enzyme was immobilized on an ammonium ion-selective electrode by different methods.An ion-selective electrode is not completely ion-specific,and interfering ions react with the ion-selective electrode membrane,altering the measured potential.Therefore,the characteristics of the effect of other ions on ammonium ion-selective electrode-based urea biosensors are considered.Based on the experimental results,the urea biosensor based on entrapment had a high response voltage of around 189 mV and fast response time of around 16 sec.Moreover,selectivity of the urea biosensor in different interfering ions was considered to elucidate the characteristics of ammonium ion-selective electrode-based biosensors.

STUDY OF CALCIUM ION-SELECTIVE ELECTRODE BASED ON A NEW NEUTRAL CARRIER

A calcium ion-setective eletrode based on a new neutral carrier was studied.The electrode gives a Nernstian response in the rang 5.9-1 Pa and the response is stable in a wide pH range.Logarithms of setectivity coefficents are -2.3 Li(+),-3.5 Na(+),-4.0 K(+),-3.7NH_4(+),-4.5 Mg(2+) and -4.4Zn(2+).

Studies of Adsorption of Cadmium Ions by Biowaste Adsorbent from Aqueous Solutions with Ion-Selective Electrodes and ICP-OES

Using environment-friendly and low-cost biowaste adsorbents as toxic metal ion removal substrates from aqueous solutions has a great economic advantage. This work evaluated pumpkin and potato peel biowastes for the adsorption of cadmium ions. The biowastes were treated with acid or base. Batch experiments were carried out by introducing a known concentration of metal ion solution into the biowaste sorbent at various pH levels. The pH and metal ion concentration was monitored with pH and cadmium ion-selective electrode continuously for two hours, and the final concentration for the metal ion after 24 hours was measured with the cadmium electrode and then confirmed with ICP-OES. L-type isotherms were obtained that fit to Freundlich model. Adsorption isotherms showed chemical adsorption and the kinetics following the second order model. Equilibrium adsorption capacity is higher than 29 mg/g at pH 5.6 when the initial concentration is 220 ppm. Dynamic cadmium adsorption capacity is 17 mg/g from aqueous solution when the feed solution is 220 ppm with pumpkin peel biowaste sorbent. The biowaste materials can be regenerated with acid washing.

COMPARISON OF CELLULOSE ACETATE POLYMER AND ELECTROLYTIC DETACHABLE COILS FOR TREATMENT OF CANINE ANEURYSMAL MODELS

Electrolytic detachable coils (EDC) have been the main embolic materi als for intracranial aneurysms. Liquid aneurysmal embolic materials represented by cellulose acetate polymer (CAP) are still in controversy. In this research, t he embolization results and pathological reactions after embolization of canine aneurysmal models with EDC or CAP were observed and compared. Methods. The canine aneurysmal models constructed by anastomosis of venous pouch es were randomly grouped. The aneurysms were respectively occluded with CAP and electrolytic detachable coils that was named by Wu electrolytic detachable coil (WEDC) and made by us. Angiogram follow ups were performed at 24 hour, 2 week , and 2 month after embolization. The occluded aneurysms were dissected in each stage for light microscopic, electron microscopic, and histochemical research. Results. The effect of embolization was significantly better with WEDC than that with CAP . Post embolized complications such as aneurysm rupture and stenosis of parent arteries could only be found in CAP group. Pathol ogical research showed that CAP mass could packed the aneurysms more densely tha n coils. Acute chemical damage of aneurysmal wall and inflammatory cell infiltra tion was prominently found in early stage after CAP embolization. Organization of thrombus inside aneurysms and formation of endothelial tissue over the orific es of aneurysmal necks could be found in both groups 2 months after embolization . But parts of coils might be exposed outside endothelial layer. Conclusions. EDC are still the most safe, efficient, and reliable instruments to embolize aneurysm. CAP should be improved further to solve the problem of stron g chemical corrosion and difficulty in control before it is widely used.

A review on the synergism between corrosion and fatigue of magnesium alloys:Mechanisms and processes on the micro-scale

Understanding the interaction between cyclic stresses and corrosion of magnesium(Mg)and its alloys is increasingly in demand due to the continuous expansion of structural applications of these materials.This review is dedicated to exploring the corrosion-fatigue mechanisms of these materials,with an emphasis on microscale processes,and the possibility of expanding current knowledge on this topic using scanning electrochemical techniques.The interaction between fatigue and corrosion of Mg alloys is analyzed by considering the microstructural aspects(grain size,precipitates,deformation twins),as well as the formation of pits.Furthermore,in the case of coated alloys,the role of coating defects in these phenomena is also described.In this context,the feasibility of using scanning electrochemical microscopy(SECM),scanning vibrating electrode technique(SVET),scanning ion-selective electrode technique(SIET),localized electrochemical impedance spectroscopy(LEIS)and scanning Kelvin probe(SKP)methods to study the corrosion-fatigue interaction of Mg alloys is examined.A comprehensive review of the current literature in this field is presented,and the opportunities and limitations of consolidating the use of these techniques to study the microscale processes involved in Mg corrosion-fatigue are discussed.

PSPICE仿真的测试性验证方法

阐明了对复杂电子设备测试性进行验证的重要性,介绍了PSP ICE软件的特点,对基于PSP ICE仿真的电子设备测试性验证方法进行了研究,提出了电子设备测试性验证的具体方案。在确定电子设备测试性验证指标的基础上,通过实例分析对方案进行验证,并对实验结果进行了分析,总结了验证过程中存在的问题。实验表明,基于PSP ICE仿真的测试性验证方法是可行的。

激光强化喷射技术在不锈钢上直接局部电沉积金

运用激光强化而喷射技术在不锈钢基体上直接局部电沉积金获得成功，经剥离试验以及白SIMS深度谱分析均表明其结合力良好。从SEM照片得到激光照射可提高镀层的致密性，改善镀层的质量；在流体流速、镀液组成及电流密度相同的情况下，激光的照射还能提高电流效率。此外，我们还研究了喷嘴至基体的距离以及流体流速对镀金线的选择性和电沉积速率的影响。

电针治疗神经根型颈椎病临床疗效Meta分析

目的:评价电针治疗神经根型颈椎病(CSR)的临床有效性。方法:通过计算机检索CNKI、Wangfang database、CHKD、VIP、Pub Med database及Cochrane library有关电针治疗CSR的随机对照试验(RTCs),按Cochrane协作网系统评价的方法进行评价,采用Rev Man 5.3软件进行统计分析。结果:9个关于电针治疗CSR的随机对照试验共529例病人纳入研究,Meta分析结果显示:电针组与普通针刺组对比,总有效率RR=1.08,95%CI为(1.02,1.15),Z=2.66,P=0.008<0.05;治愈率RR=1.52,95%CI(1.20,1.91),Z=2.32,P=0.0004<0.05;根据日本田中靖久颈椎病症状20分法量表评分情况[MD=2.41,95%CI(2.22,2.59),Z=25.99,P<0.00001],差异均具有统计学意义,表明电针治疗CSR的临床疗效优于普通针刺。而根据MPQ评分情况[MD=-1.79,95%CI(-3.68,0.10),Z=1.86,P=0.06>0.05],差异无统计学意义,表明在两组治疗CSR后疼痛症状改善相同。结论:本研究结果表明电针治疗CSR具有较好的临床疗效,但由于缺乏高质量文献的纳入及本研究存在敏感性不确定的因素,因此需要更多设计严格的、大样本的、多中心随机对照试验进一步验证。

酸性氧化电位水防治大肠埃希菌腹膜炎的实验观察

目的 :观察酸性氧化电位水 (electrolyzed strong acid water,EOW)对大肠埃希菌所致小白鼠腹膜炎的治疗作用及毒性反应。方法 :实验分酸性氧化电位水毒性测定组、治疗观察组和对照组 ,治疗组小鼠用大肠埃希菌 O13 6K∶ 78株经腹腔接种后 ,制造腹膜炎模型 ,然后采用不同的 p H值 ,氧化还原电位(ORP)为 950～ 1150 mv的酸性氧化电位水对小鼠腹膜炎治疗及毒性作用进行观察。结果 :4组不同 p H值酸性氧化电位水治疗小鼠腹膜炎均有一定的作用 ,以 p H2 .8组疗效最为理想 ,小白鼠存活率为 10 0 % ;腹腔中感染的大肠埃希菌消失或存在极少量 ,病理切片可见腹膜炎症反应明显降低 ,增厚的腹膜变薄 ,血管充血减轻。结论 :酸性氧化电位水作为一种替代的抗菌消毒剂 ,在杀灭大肠埃希菌和治疗小鼠腹膜炎具有一定的作用 ,并且在尿毒症患者腹膜透析过程中 ,替代抗生素防治感染具有进一步研究和应用推广的价值。

BaCe_(0.8)Y_(0.2)O_(3-α)的溶胶-凝胶法合成及其电性能

用溶胶 -凝胶法合成了BaCe0 8Y0 2 O3 -α固体电解质前驱体 ,并以低于通常固相反应 15 0～ 2 5 0℃的温度 (即14 0 0～ 15 0 0℃ )进行了烧结 .以烧结体样品为固体电解质、多孔性铂为电极 ,组成氢及氧浓差电池、氢 -空气燃料电池 ,测定了BaCe0 8Y0 2 O3 -α烧结体的质子和氧离子迁移数以及燃料电池的性能 ,并与高温固相反应法合成的样品进行了比较 .结果表明 ,烧结温度能显著影响溶胶 -凝胶法合成样品的质子迁移数及燃料电池性能 .烧结温度≥ 14 5 0℃时 ,质子迁移数近似为 1,燃料电池性能亦较高 ,烧结温度 <14 5 0℃时 ,质子迁移数 <1,燃料电池性能亦较低 .在14 0 0～ 15 0 0℃烧结的样品中 ,14 5 0℃下烧结的样品具有最高的电池性能 。

基于Multisim10.1频率自动跟踪锁相环电路的仿真分析

利用Multisim10.1软件对高频电路频率自动跟踪锁相环进行了仿真分析;通过改变电阻大小调整振荡波形的脉冲宽度,调整积分电路的电容大小能找出最佳锁相范围的数值大小,改变电容大小调整波形是否同步和改变信源的频率找同步范围,从而实现频率自动追踪。仿真结果与实际理论相吻合,虚拟仿真实例的结论证明了将Multisim10.1合理引入到高频电路实验教学后,能将一些抽象、枯燥的电子线路理论教学变得具体和生动,有利于提高电子线路理论课的教学质量。

不同存放条件对酸性氧化电位水理化性能和杀菌效果的影响

为观察不同存放条件对瓶装酸性氧化电位水理化性能及杀菌效果的影响,在实验室用仪器法和定量杀菌试验法进行了实验。结果,在54℃存放14d的酸性氧化电位水出现氧化还原电位下降、pH值升高;对金黄色葡萄球菌杀灭99.9％以上所需时间,载体定量法由贮存前的5min增加到10min,悬液定量法由0.5min增加至1min。结果显示,酸性氧化电位水经不同条件下贮存,对其理化性能和杀菌效果均有影响。

酸性氧化电位水杀菌效果及其对内镜清洗消毒效果观察

采用载体定量杀菌试验和模拟现场消毒试验方法,对酸性氧化电位水杀菌作用和内镜清洗消毒效果进行了试验研究。结果,新生产的酸性氧化电位水原液平均含有效氯118.7 mg/L、氧化还原电位1200 mV、pH2.29。用该酸性氧化电位水原液浸泡作用20 m in,对载体上枯草杆菌黑色变种芽孢杀灭对数值>3.0。用该酸性氧化电位水原液经内镜清洗消毒机循环冲洗20 m in,对模拟塑料管道内枯草杆菌黑色变种芽孢清除对数值>4.0。医疗器械模拟消毒现场试验对止血钳齿部枯草杆菌黑色变种芽孢浸泡作用30 m in,杀灭对数值>3.0。结论,该酸性氧化电位水对清洁条件下载体上枯草杆菌黑色变种芽孢杀灭效果较好,模拟现场消毒试验结果达到规范要求。

部队战救信息系统中制表控件的应用研究

阐述了在部队战救信息系统开发过程中,如何利用第三方电子报表控件formula one来解决应用系统中复杂的不规则中式报表不能灵活生成和修改的问题。经过实战开发应用,显著提高了系统开发过程中报表应用的灵活性和报表开发的效率。