Ce^4＋／Ce^3＋缓冲溶液流动注射电势检测法测定维生素C

以Ce4+/Ce3+氧化还原体系作缓冲溶液,用流动注射电势检测法测定了维生素C,将样品注射于以0.1mol/L K2SO4作支持电解质的Ce4+/Ce3+缓冲溶液试剂流, 以流通型氧化还原电势检测电极检测维生素C与Ce4+反应引起的氧化还原电对的电势变化,对3.0×10-4mol/L Ce4+/3.0×10-4mol/L Ce3+缓冲溶液,测定维生素C的线性范围为1.0×10-4～6.0×10-4mol/L,检出限为1.3×10-5mol/L,相对标准偏差为0.36%(n=4),分析频率为120次/小时.     

流动注射化学发光法快速测定中药黄芪中的痕量铬

利用Cr3+对鲁米诺-H2O2化学发光反应的催化作用,流动注射化学发光法的优点,建立测定Cr3+的新方法,并通过H2SO3的还原作用,使Cr6+还原为Cr3+,从而实现对总铬的测定。确定此方法的最佳条件:负高压500V;鲁米诺浓度为2.50×10-4mol/L;过氧化氢的浓度为4.00×10-2mo1/L,鲁米诺溶液的pH为12,铬(Ⅲ)试液的pH为5。线性范围为1.0×10-6mg/mL～1.0×10-4mg/mL,检出限(S/N=3)为6.60×10-7mg/mL,对浓度为6.00×10-6mg/mLCr3+的标准溶液进行11次平行测定,其相对标准偏差为0.6%。该法成功地实现对中药黄芪样品中痕量铬的测定。     

全微机化示波极谱仪的应用--地质样品中钨和钼的测定

应用全微机化示波极谱仪 (简称JPS) ,测定地质样品中的微量钨、钼。在氯酸钾 -苯羟乙酸 -辛可宁 -硫酸体系中钨、钼的峰电位分别为 - 0 82V (vs.SEC)、 - 0 4 2V (vs.SEC) ,钨、钼浓度分别在 1 39× 1 0 -9～2 6× 1 0 -6mol/L、2 6× 1 0 -9～ 2 1× 1 0 -6mol/L范围内与峰电流呈线性关系。检出限为钨 1 3× 1 0 -9mol/L、钼 2 7× -10 mol/L。特有的剥谱技术和科学的软件数学处理及自动化寻峰读值 ,对于微量元素及复杂样品的测定 ,有其独到的优势。     

橙皮甙的电化学行为研究

用单扫示波极谱法,橙皮甙在0.1mol/LKH_2PO_4缓冲溶液中(pH4.60)有一灵敏的二阶导数峰,25℃时峰电位为-1.43V(vs、SCE),峰电流与橙皮甙浓度在2.5×10~(-7)～4.0×1O~(-5)mol/L范围内有良好的线性关系,检测限为1.2×10~(-7)mol/L。用本法测定了中药陈皮中总黄酮的含量,其结果令人满意。实验证明橙皮甙的电极反应机理为双电子的不可逆过程。此外,还证明了H_2O_2和·OH自由基可催化该还原电流,并讨论了橙皮甙对超氧阴离子自由基的清除作用。     

巯基丁二酸镍(Ⅱ)自组装单分子层修饰金电极的制备及H2O2传感器的研制

制备了巯基丁二酸镍(Ⅱ)(NiL-SH)自组装单分子层修饰金电极,制做了测定H2O2 的电流型生物传感器.NiL-SH在电极表面有一个不可逆的还原峰,传感器对H2O2的还原具有快速电催化响应(＜10s).采用电子扫描电镜(SEM)对电极表面进行了表征,探讨了电极的电化学反应性质.研究了各种因素,如pH、工作电位等,对传感器响应电流的影响.用循环伏安法测定H2O2,线性范围为5.0×10-6～3.0×10-3mol /L (R = 0.999),检出限为2.0×10-6mol/L.该电极具有模拟酶特性,米氏常数KappM＝2.78mmol/L.实验表明,传感器的稳定性、灵敏度和选择性都比较好,可以用于现场测定.     

有机溶剂对α-萘乙酸无保护性流体室温磷光性质的影响

在无保护性介质存在下,仅以Na_2SO_3作化学除氧剂,用KI或TlNO_3作重原子微扰剂,就能直接诱导α-萘乙酸(α-NAA)水溶液强而稳定的流体室温磷光(RTP)发射。磷光峰位波长λ_(ex)/λ_(em)分别为281/495,522nm和289/492,521nm。当体系中引入少量有机溶剂时,体系RTP强度,达到稳定所需的光诱导时间及重原子微扰剂的选择都受到较大影响。在维持乙醇或乙腈含量<1％条件下,用KI作重原子时,α-NAA的分析曲线线性范围为6.0×10~(-7)～1.6×10~(-5)mol/L和1.6×10~(-5)～8.0×10~(-5)mol/L,相关系数分别为0.999和0.997,检出限为3.6×10~(-8)mol/L。用TlNO_3作重原子时,分析曲线线性范围为6.0×10~(-7)～4.0×10~(-5)mol/L,相关系数为0.997,检出限为4.3×10~(-8)mol/L。     

用聚合亚甲蓝修饰的酶电极对牛奶中青霉素残留测定研究

将青霉素酶与亚甲蓝用循环伏安法共聚合在玻碳电极上,制成青霉素酶电极,通过交流阻抗谱对酶电极表征。在一定电位范围内,青霉素微小浓度变化与亚甲蓝还原峰电流成正比,据此可间接测定了牛奶中残留青霉素含量,在磷酸缓冲溶液和牛奶中,线性范围分别为2.81×10-4～2.81×10-3mmol·L-1和1.12×10-3～2.81×10-3mmol·L-1。     

电容耦合非接触电导检测器的研制

利用电容耦合的原理,将环形电极直接包在石英毛细管外壁,研制成一种电容耦合非接触电导检测(C4D).采用毛细管电泳技术评价了该检测器,对碱金属、碱土金属的浓度检测限为5×10-7～5×10-6mol/L,响应值在10-6～10-3mol/L的线性相关系数R＞0.999.该检测器结构简单,彻底克服了电化学检测器电极易污染的缺点.     

吡哌酸离子选择性电极的研制和应用

本文研究了以PPA-TBP为电活性物质的PVC膜吡哌酸离子选择性电极的制备方法.在HAc-NaAc(pH=3.7)底液中,电极响应的线性范围1.0×10-3～1.0×10-5mol/L,检测限为5.0×10-6mol/L,级差为28mV/pc.并用该电极测定了吡哌酸片剂中吡哌酸的含量,结果满意.     

普鲁士蓝修饰丝网印刷电极的葡萄糖生物传感器

在丝网印刷电极上,通过电沉积普鲁士蓝和溶胶-凝胶固定酶两步修饰法,制得一种葡萄糖生物传感器。该传感器利用普鲁士蓝对酶催化反应产物之一的过氧化氢的选择性催化还原特性,实现对葡萄糖的检测。在-0.05V工作电位下,传感器灵敏度3.289μA/(mol/L),线性范围5.00×10-6～2.44×10-3mol/L,检测极限1.43×10-6mol/L,并具有良好的重复性、稳定性和抗干扰能力。同时对小鼠血清样品中的葡萄糖进行检测,该传感器具有实际应用价值。     

X射线光电子能谱仪应用——特殊样品测量及复杂图谱解析

x射线光电子能谱(XPS)是材料表面元素定性和半定量分析的重要手段之一。在XPS测量实验中,使用绝缘方法来安置导电不均匀样品到导电的样品台上进行常规XPS测量,方便地得到满意的图谱数据;在数据处理中,针对扫描谱图中的峰位、峰强度、峰宽和峰形等情况,利用XPS图谱分析软件的拟合分析功能,对多价态混合的复杂样品(例如:Ce和Fe的多价态样品)的XPS图谱进行处理,采用单一价态的实验数据为模版对混合图谱进行拟合处理,比较容易地获得常规方法不易得到的不同价态的定性及半定量结果。本文对以上方法分别作举例说明。     

富铈混合稀土对Al-24%Si合金的变质效果及机理

采用富铈混合稀土对Al-24%Si合金进行了变质处理,用扫描电镜对合金的硅相形貌与尺寸进行了研究,分析了变质效果及机理。结果表明:富铈混合稀土对合金中初晶硅及共晶硅均有良好的变质效果,变质后初晶硅平均尺寸由100μm细化到50 μm左右,共晶硅细化成颗粒状或短杆状;初晶硅细化是通过稀土原子与氧原子反应生成稀土化合物(CeO_2),它成为硅非均匀形核核心,生成了大量硅晶晶核来实现的;共晶硅细化是通过硅相生长界面前沿形成很强的稀土原子富集层,造成成分过冷降低硅生长速度来实现的。     

Prospective scintillation electron detectors for S(T)EM based on garnet film scintillators

The performance of a scintillation electron detector for a scanning electron microscope and/or a scanning transmission electron microscope (S(T)EM) based on new epitaxial garnet film scintillators was explored. The LuGAGG:Ce and LuGAGG:Ce,Mg film scintillators with chemical formula (Ce_0.01Lu_0.27Gd_0.74)_3–wMg_w(Ga_2.48Al_2.46)O₁₂ were prepared and their cathodoluminescence (CL) and optical properties were studied and compared with the properties of current standard bulk single crystal YAG:Ce and YAP:Ce scintillators. More specifically, CL decay characteristics, CL emission spectra, CL intensities, optical absorption coefficients, and the refractive indices of the mentioned scintillators were measured. Furthermore, electron interaction volumes with absorbed energy distributions, photomultiplier (PMT) photocathode matchings, modulation transfer functions (MTF), and the photon transport efficiencies of scintillation detectors with the mentioned scintillators were calculated. A CL decay time for the LuGAGG:Ce,Mg film scintillator as low as 28 ns with an afterglow of only 0.02% at 1 μs after the e‐beam excitation was observed. As determined from calculated MTFs, the scintillation detectors with the new film scintillators lose contrast transfer ability above 0.6 lp/pixel, while the currently commonly used YAG:Ce single crystal scintillators already do so above 0.1 lp/pixel. It was also calculated that the new studied film scintillators have an 8% higher photon transfer efficiency, even for a simple disk shape compared with the standard bulk single crystal YAG:Ce scintillator. The studied LuGAGG:Ce,Mg epitaxial garnet film scintillators were evaluated as prospective fast scintillators for electron detectors, not only in S(T)EM but also in other e‐beam devices.     

0.2%Ce合金化对铸造Al-Cu合金热裂倾向的影响

为了探索改善高强度铸造 Al- Cu合金抗热裂性能的途径 ,采用液淬的方法 ,通过测量热平衡曲线、溶质浓度分布及金相显微分析等手段 ,研究了 0 .2 % Ce对Al- 4.5 Cu和高强度铸造 Al- Cu- Mn- Ti合金的凝固行为的影响。研究结果表明 ,Ce的加入 ,改变了试验合金的凝固特性 ,并影响了合金的枝晶生长行为 ,其综合作用使合金组织明显细化和均匀化 ,且二次晶臂发达 ,对提高高强度铸造 Al- Cu合金抗热裂性能具有积极作用。对试验合金的热裂抗力测试证明了这一观点     

稀土元素铈对超级双相不锈钢热变形能力的影响

利用Gleeble-3800热模拟试验机、光学显微镜、扫描电镜和能谱仪等研究了稀土元素铈对铸态00Cr25Ni7Mo4N超级双相不锈钢在应变速率为5 s-1、变形温度为1 100,1 150,1 200℃下热变形行为的影响。结果表明:稀土元素铈能够降低该钢中氧、硫含量,使钢中的夹杂物由硫化物变成稀土夹杂物,从而在一定程度上改善了该钢的热变形能力;铈的较佳添加量为0.165%~0.220%,适宜的热变形温度为1 150~1 200℃。     

Fe-Mo-Mn-Sn-Ce-C烧结合金体系与强化烧结工艺研究

研究了合金成分，烧结气氛对Fe-Mo-Mn-Sn-Ce-C系合金的力学性能与烧结温度的影响以及在烧结合金中的作用机理，结果表明：适量的Mn、Sn、混合稀土和氨燃烧氮基保护气氛均可加速该系合金的烧结进程，降低其烧结温度，改善其力学性能，而且具有协同、叠加强化效果。其强化作用主要体现在稀土元素的脱氧保碳、变质夹杂物，细化晶粒，Mn,Sn元素的固溶强化以及氨燃烧氮基保护气氛对烧结热效率，合金表层脱碳状况，烧结活化能的改善等方面，该系合金在氨燃烧氮基保护气氛中的合适烧结温度范围为1025～1075℃，比Fe-Mo-Ni-C系合金的烧结温度降低了120～180℃。     

Surface micromorphology of dental composites [CE‐TZP]‐[Al2O3] with Ca+2 modifier

The objective of this study was to characterize the three‐dimensional (3D) surface micromorphology of the ceramics produced from nanoparticles of alumina and tetragonal zirconia (t‐ZrO₂) with addition of Ca⁺² for sintering improvement. The 3D surface roughness of samples was studied by atomic force microscopy (AFM), fractal analysis of the 3D AFM‐images, and statistical analysis of surface roughness parameters. Cube counting method, based on the linear interpolation type, applied for AFM data was used for fractal analysis. The morphology of non‐modified ceramic sample was characterized by the rather big (1–2 μm) grains of α‐Al₂O₃ phase with a habit close to hexagonal drowned in solid solution of t‐ZrO₂ with smooth surface. The pattern surfaces of modified composite content a little amount of elongated prismatic grains with composition close to the phase of СаСеAl₃О₇ as well as hexahedral α‐Al₂O₃‐grains. Fractal dimension, D, as well as height values distribution have been determined for the surfaces of the samples with and without modifying. It can be concluded that the smoothest surface is of the modified samples with Ca⁺² modifier but the most regular one is of the non‐modified samples. A connection was observed between the surface morphology and the physical properties as assessed in previous works. Microsc. Res. Tech. 78:840–846, 2015. © 2015 Wiley Periodicals, Inc.     

Electron microscope studies of nano-domain structures in Ru-based magneto-superconductors: RuSr(2)Gd(1.5)Ce(0.5)Cu(2)O(10-delta) (Ru-1222) and RuSr(2)GdCu(2)O(8) (Ru-1212)

Microstructures of the RuSr(2)Gd(1.5)Ce(0.5)Cu(2)O(10-delta) (Ru-1222) and RuSr(2)GdCu(2)O(8) (Ru-1212) magneto-superconductors have been investigated by using selected-area electron diffraction, convergent-beam electron diffraction, dark-field electron microscopy and high-resolution electron microscopy at room temperature. Both Ru-1212 and Ru-1222 consist of nm-size domains stacked along the [Formula: see text] direction, where the domains are formed by two types of superstructures due to ordering of rotated RuO(6) octahedra about the c-axis. In Ru-1212, both primitive-and body-centered tetragonal superstructures (the possible space groups: P4/mbm and I4/mcm) are derived to form the corresponding nm-domains. It is of great interest that Ru-1212 consists of domains of two crystallographically different superstructures, while the similar domains observed in Ru-1222 have crystallographically identical superstructure with an orthorhombic symmetry (possible space group: Aeam), related by 90 degrees rotation around the c-axis (Yokosawa et al., 2003, submitted for publication).     

Effect of shock front geometry on shock depolarization of Pb(Zr(0.52)Ti(0.48))O(3) ferroelectric ceramics

By use of experimentation, we detected a shock wave geometry effect on the depolarization of poled Pb(Zr(0.52)Ti(0.48))O(3) (PZT 52∕48) ferroelectrics. It follows from the experimental results that shock front geometry is one of key parameters in the shock depolarization of PZT 52∕48 ferroelectrics. This shock depolarization effect forms a fundamental limit to miniaturization of explosive-driven shock-wave ferroelectric generators (FEGs). Based on obtained experimental results, we developed miniature generators that reliably produce pulsed voltages exceeding 140 kV.     

Antennal sensilla of Eucryptorrhynchus chinensis (Olivier) and Eucryptorrhynchus brandti (Harold) (Coleoptera: Curculionidae)

Eucryptorrhynchus chinensis (Olivier) (Coleoptera: Curculionidae) and E. brandti (Harold) (Coleoptera: Curculionidae) are the two most important pests of tree‐of‐heaven, Ailanthus altissima (Mill.) Swingle and its variety Ailanthus altissima var. Qiantouchun in China. They are also considered potential biological control agents for tree‐of‐heaven in North America. In this study, the external morphologies and antennal sensilla of both species were examined using scanning electron microscopy to better understand their host‐finding mechanisms. Eleven morphological sensilla types were recorded, that is, Böhm bristles, six types of sensilla chaetica (Sch. 1–6), two types of sensilla basiconica (Sb. 1–2), and two types of sensilla trichodea (St. 1–2). Sch. 5 were absent from the antennae of E. chinensis, while Sch. 2 were absent from the antennae of E. brandti. Abundant cuticular pores were present on the antennae of both species. Three types of sensilla on the antennae of E. chinensis that were not found in a previous study, and ten different types of sensilla on the antennae of E. brandti were identified for the first time. The possible functions of the sensilla types are discussed based on a comparison with previous studies. Four types of sensilla (Sb. 1, Sb. 2, St. 2, and Sch. 6) on the antennae of both species indicate chemoreception may play a significant role in host location. Microsc. Res. Tech. 76:968–978, 2013. © 2013 Wiley Periodicals, Inc.