米粒状氧化铜化学修饰电极的制备及其对葡萄糖的检测

采用水热合成法与原位分解法相结合, 在不使用软模板和强碱条件下制备得到了米粒状氧化铜(CuO)。将得到的CuO材料与Nafion溶液混合, 制作成化学修饰电极(CME), 开展葡萄糖的无酶检测。采用X射线衍射仪(XRD)和扫描电子显微镜(SEM)分别对所制备的材料和电极的结构、形貌进行表征、分析。采用线性扫描伏安法、循环伏安法、安培响应和交流阻抗技术对所制备电极进行电化学性能测试。研究结果表明: 所制备的CuO形貌在微观下酷似米粒, 长度为0.5~ 1.0 μm, 直径为250~320 nm。当CuO修饰量为0.35 mg (电极表面积为0.22 cm²)时, 修饰电极对葡萄糖具有较好的电化学检测性能。在0.0357~2.361 mmol/L浓度范围内存在良好的线性关系, 其线性方程为: I_pa(mA)= -0.00187+0.05239c (mmol/L), R²=0.998。检出限为 0.0647 μmol/L, 灵敏度为950.36 μA·L/(mmol·cm²), 且具有良好的选择性和可靠性。     

Ba(Zr0.15Ti0.85)O3厚膜的介电与铁电性能研究

本研究采用流延法制备Ba(Zr_0.15Ti_0.85)O₃(BZT)厚膜样品。采用扫描电子显微镜分析样品形貌; 采用LCR测试仪和Sawyer-Tower电路法测量样品的介电与铁电性能。结果表明, BZT厚膜具有明显的介电弛豫特征, 击穿电场强度可达60 kV/cm以上, 饱和极化强度可达58.1 μC/ cm², 剩余极化强度(Pr)为20.9 μC/ cm²。     

基于花状MoS2微米材料的葡萄糖生物传感器的制备及其性能研究

本研究采用水热法制备了花状MoS₂微米材料, 将其作为电极构建葡萄糖生物传感器, 并研究了相关性能。结果表明: 水热法制备的MoS₂呈花状, 具有较好的结晶质量, 尺寸约为3.6 μm, 比表面积约为9.646 m²/g; MoS₂电极具有优良的电催化活性, 且电阻抗较小, 使得传感器对葡萄糖具有较好的响应。葡萄糖检测结果表明, 该传感器在0~20 mmol/L范围内, 氧化峰电流与葡萄糖浓度呈良好的线性关系, 相关系数(R)为0.9653, 灵敏度为262 μA•L/mmol。     

γ-NaxCoO2粉体的聚丙烯酸钠凝胶法制备及其表征

本研究发展了一种用于制备氧化物热电材料γ-Na_xCoO₂粉体的化学合成方法——聚丙烯酸钠(PAAS)凝胶法。主要研究了PAAS/Co²⁺摩尔比、原料浓度和煅烧温度对产物相组成及微观形态的影响规律, 探讨了物相形成机制, 同时用该方法结合SPS制备了不同Na离子浓度的Na_xCoO₂多晶样品, 并对其热电性能进行了表征。结果表明, PAAS/Co²⁺摩尔比对产物相组成产生了显著影响, 随着PAAS/Co²⁺摩尔比的增加, 样品的相组成由Co₃O₄相向单相γ-Na_xCoO₂转变, 合适的PAAS/Co²⁺摩尔比为0.8~1.1。而反应原料浓度对产物相组成的影响存在一个临界值(0.025 mol/L), 大于临界值抑制单相形成, 小于临界值促进单相形成。煅烧温度的升高有助于γ-Na_xCoO₂单相的形成, 800℃煅烧得到γ-Na_xCoO₂单相, 晶粒形态呈片状, 平均厚度约200 nm, 片状方向的尺寸在1~4 μm之间。随着Na含量的增加, 样品的Seebeck系数增大, 电导率增加, 热导率降低, 最终导致ZT值大幅增加。     

氧化镍/镍/碳微球原位制备及葡萄糖传感性能

以葡萄糖、六水合氯化镍和尿素为原料, 通过水热反应一步制备前驱体Ni(OH)₂/C, 在高纯度氮气中煅烧获得NiO/Ni/C微球三元复合材料。采用扫描电镜(SEM)、透射电镜(TEM)、X射线衍射(XRD)、X射线光谱(EDS)和拉曼(Raman)等手段, 分析NiO/Ni/C微球三元复合材料的形貌结构以及物相组成。结果表明: NiO/Ni/C微球为珊瑚花状结构, 直径约1.7 μm, Ni、NiO呈立方相。通过循环伏安法和计时电流法研究了NiO/Ni/C微球三元复合材料的电化学行为及葡萄糖传感性能。当Ni/NiO摩尔比为0.19时, 形成的NiO/Ni/C三元复合微球具有优异的葡萄糖传感性能, 其灵敏度为241.09 μA·mmol/(L·cm²), 线性响应范围为10 μmol/L~5.05 mmol/L, 最低检测限位10 μmol/L。该传感器具有灵敏度高、抗干扰能力强以及稳定性好等特点。     

(Ca,Fe)共掺铈酸镧陶瓷的制备及红外辐射性能研究

以La₂O₃、CeO₂、CaO和Fe₂O₃为起始原料, 采用高温固相烧结工艺制备得到(Ca,Fe)共掺铈酸镧(La_1.9Ca_0.1Ce_1.9Fe_0.1O₇)红外辐射陶瓷材料。采用X射线衍射仪、扫描电子显微镜、能谱仪、紫外-可见-近红外(UV-Vis-NIR)分光光度计分别对样品的物相组成、显微结构、化学成份、UV-Vis-NIR反射率及UV-Vis吸收进行了表征, 同时采用IR-2双波段红外发射率测量仪测试了样品3~5 μm波段的红外发射率。结果表明: 掺杂元素(Ca, Fe)均固溶进入铈酸镧晶格, 共掺后样品的晶体结构也为萤石结构; (Ca,Fe)共掺样品内部形成杂质能级, 强化了自由载流子吸收与杂质能级吸收, 使样品红外短波段(0.75~5 μm)性能由高反射转变为高吸收(辐射), 其中在0.75~2.5 μm波段的平均红外吸收率为0.88, 3~5 μm波段的红外发射率为0.752, 与未掺杂样品相比分别提高了1660%与60%。     

核壳结构氧化镍/碳微球的制备及葡萄糖传感性能

以碳球为模板, 六水合氯化镍和尿素为原料, 通过水热反应制备前驱体Ni(OH)₂/C, 在高纯氮气中煅烧获得核壳结构的NiO/C微球。采用扫描电镜(SEM)、X射线衍射(XRD)、X射线光谱(EDX)和热重分析(TGA)等技术手段, 分析NiO/C微球的形貌结构以及物相组成, 结果表明: NiO/C微球直径约1.4 μm, 由厚度为50 nm的纳米片包覆碳球形成花状核壳结构, NiO呈立方相。通过循环伏安法和计时电流法研究了NiO/C微球的电化学行为及葡萄糖传感能力。与单纯NiO相比, NiO/C具有优异的葡萄糖传感性能, 其灵敏度为31.37 mA/(mmol·L^-1·cm²)线性响应范围为2~1279 μmol/L, 最低检测限为2 μmol/L。该传感器具有灵敏度高、抗干扰能力强和稳定性好等特点。     

海藻酸钠离子凝胶法制备直通孔氧化铝多孔陶瓷

利用海藻酸钠的离子凝胶过程, 采用溶剂置换结合冷冻干燥的工艺, 成功制备了具有高度有序六方排列的直通孔多孔氧化铝陶瓷, 整个工艺过程及所使用的原料都是环境友好的。研究结果表明, 1500℃烧结2 h样品的孔径尺寸在200 μm左右, 且与固相含量的关系不大, 而孔壁上存在0.3 μm~0.5 μm的小孔。通过控制浆料中氧化铝的固相含量可以对材料的性能进行有效地调控, 研究表明, 随着固相含量从5wt%提高到15wt%, 材料的密度从0.87 g/cm³提高到1.16 g/cm³, 渗透率从2.57×10^-11 m²下降到2.16×10^-11 m², 而抗压强度从(18.9±3.2) MPa提高到(44.2±5.4) MPa, 平行孔道方向的热导率从2.1 W/(m·K)提高到3.1 W/(m·K), 而垂直孔道方向的热导率从1.3 W/(m•K)提高到1.7 W/(m·K), 并且平行孔道方向热导率的增加幅度要明显大于垂直孔道方向。     

生物活性玻璃纤维的基因转染研究

生物活性玻璃由于含有钙、磷成分, 因此在基因转染方面具有应用潜能。本研究通过溶胶-凝胶结合静电纺丝技术制备了具有连续介孔或分级纳米孔的微纳米生物活性玻璃纤维(BGF), 并将其用于基因转染。实验结果显示, BGF在无血清培养基中可大量释放Ca²⁺和PO₄^3-, 这些释放的离子在沉积的同时可装载质粒DNA, 起到基因转染载体的作用, 转染效率与BGF之间具有剂量依赖性。当质粒浓度为1 μg/mL、BGF浓度为1000 μg/mL时, 细胞的转染效率可达对照组(脂质体转染试剂)的50%以上。其转染机理与传统的磷酸钙基因转染类似, 而其较好的离子溶出保障了其使用的稳定性, 有望替代纳米磷酸钙转染体系用于基因传输。     

不同晶相MnS制备及光解H2S制氢性能研究

采用溶剂热法成功制备了具有立方结构的α-MnS和六方结构的γ-MnS。通过X射线衍射(XRD), 扫描电子显微镜(SEM), 透射电子显微镜(TEM)、高分辨透射电镜(HRTEM)、选区电子衍射(SAED)和紫外-可见吸收光谱(UV-Vis), 对样品的物相组成、显微形貌、光学性质进行了研究, 并对不同晶相MnS在可见光(λ > 420 nm)和全光谱下光解H₂S制氢性能进行了研究。结果表明: α, γ-MnS在可见光下都具有光解H₂S制氢活性, 且相比于热力学稳定相的α-MnS (4.24 μmol/(g·h)), 亚稳态的γ-MnS (23.38 μmol/(g·h))具有更好的催化性能。相对于可见光, α, γ-MnS在全光谱下的产氢速率明显提高, 其中γ-MnS在全光谱下具有最大的光解H₂S制氢活性, 其产氢速率可达 2272.69 μmol/(g·h)。值得注意的是, 在6 h的光催化测试过程中, α, γ-MnS都展示较好的抗光腐蚀能力和光催化稳定性。此外, 对α, γ-MnS光催化分解H₂S制氢机理进行了分析, 通过对α, γ-MnS光电化学性质的研究, 对其光催化活性存在差异的原因进行了探讨。     

Recovery of surfactant SDS and Cd2+ from permeate in MEUF using a continuous foam fractionator

The purpose of this study was to investigate the use of foam fractionation to recover valuable surfactant (SDS) and metal ion (Cd²⁺) in the permeate of micellar-enhanced ultrafiltration (MEUF). The effects of operating factors, such as time, air flow rate, feed flow rate, liquid height, foam height, feed surfactant concentration, ethanol concentration and temperature on separation characteristics were studied in the continuous operation. When the concentrations of surfactant (SDS) and metal ion (Cd²⁺) in the feed solution were 500 mg/L and 10 mg/L, an enrichment ratio of 3.1 was achieved for SDS along with 52% removal fraction, as well as 99.35% Cd²⁺ was removed, after optimization of different process parameters. As the optimized results, the air and liquid flow rates were 100 L/h and 5 L/h, liquid and foam heights were 45 cm and 66 cm, respectively, sparger pore size was 10 μm. The Cd²⁺ concentration in the effluent was lower than 0.1 mg/L which could meet the integrated wastewater discharge standard (the first grade of national discharge standards in China).     

Cadmium Selective PVC-Membranes Sensor Based on 1, 2-Bis (Quinoline-2-Carboxamido) -4-Chlorobenzene as a Neutral Carrier

The 1, 2-bis(quinoline-2-Carboxamido)-4-chlorobenzene (H₂Clbqb) was used as an excellent ionophore in the construction of a cadmium(II)-selective PVC-based membrane sensor. The influences of membrane compositions on the potentiometric response of the electrodes have been found to substantially improve the performance characteristics. The best performance was obtained with a membrane composition of (H₂Clbqb) (5%): PVC (31%): DBP (61%): NaTPB (3%). The sensor shows a Nernestian response for cadmium ions over a wide concentration range (1.0times10⁶ to 1.0 times 10^-1 mol.L^-1) with slope of 30.3 plusmn0.4 mV decade¹. The limit of detection was 8.0 times10^-7 mol.L^-1. It illustrates a relatively fast response time in the whole concentration range (< 10 s) and it can be used for at least 8 weeks without any divergence in potential. The electrode can be used in the pH range from 2.4 to 9.0. The selectivity coefficient of some alkali, alkaline earth, transition and heavy metal ions towards Cd²⁺ion have been determined. The results show proposed Cd sensor is selective over a number of mono, bi- and trivalent cations such as Pb²⁺, Fe³⁺, Ni²⁺, K⁺, and Mg²⁺. The analytical usefulness of the proposed electrode has been evaluated by its application in the determination of cadmium in real samples. It was successfully applied for the direct determination of Cd²⁺ in standard and real sample solutions.     

残余相和烧结温度对碳化硅陶瓷抗混酸腐蚀特性的影响

本工作主要研究了残余相和晶粒尺寸对碳化硅的抗混酸(HF-HNO₃)腐蚀特性。通过不同的烧结方法(固相烧结、液相烧结、反应烧结)制备出残余相不同的碳化硅材料。结果表明: 与液相烧结碳化硅(LPS SiC)和反应烧结碳化硅(RB SiC)相比, 固相烧结碳化硅(SSiC)具有更好的腐蚀抗性, 这是由于残余相石墨的抗腐蚀性强, 以及残余相在材料中形成不能相互联通的岛状结构。通过调节碳化硅的烧结温度, 可以影响材料中的晶粒尺寸, 研究结果发现相同烧结温度下随着残余相含量的增加, 材料腐蚀失重线性增加, 对曲线进行线性拟合, 其Y轴截距的绝对值代表不含碳的试样在该烧结温度下的腐蚀失重。研究表明随着烧结温度由2100℃升高到2160℃, 晶粒尺寸由2 μm增加到6 μm。此时其Y轴截距的绝对值分别为9.22(2100℃), 5.81(2130℃), 0.29(2160℃), 表明晶粒尺寸的增加有利于提高材料的抗腐蚀能力。     

Further study on different dopings into PbWO4 single crystals to increase the scintillation light yield

Since we presented our preliminary result (Nucl. Instr. and Meth. A 486 (2002) 170) at SCINT2001, we have continued our efforts to increase the light yield (LY) of PbWO₄ scintillators by extending different dopings with an aim to find a possibility of using PbWO₄ successfully in Positron Emission Tomography (PET). Overall result obtained for single doping as well as double and tripple co-dopings are summarized, including decay characteristics and radiation hardness. The LY in non-doped PbWO₄ crystals with a size of 10×10×(20–30) mm³ is 25–35 photolectrons/MeV (phe/MeV) corresponding to 3–4% of the LY in BGO, when measured with a bialkali photomultiplier during a gate of 1 μs. The maximum LY increased to 49 phe/MeV for single doping with Mo⁶⁺, 80 phe/MeV for double co-doping of Mo⁶⁺+Sb⁵⁺, and 85 phe/MeV for tripple co-doping of Mo⁶⁺+Cd²⁺+Sb⁵⁺. The radiation hardness is larger than 10⁵ Gy for each of the samples co-doped with Mo⁶⁺+Sb⁵⁺ and Mo⁶⁺+Cd²⁺+Sb⁵⁺, while it is much poorer in PWO:Mo⁶⁺. In each of these co-doped samples, a medium-speed green emission in the microsecond range is created besides the fundamental fast (a few nanoseconds range) blue one, giving a peak at 500 nm in the radioluminescence spectrum similarly as in PWO:Mo⁶⁺.     

Optimum thickness of carbon stripper foils in tandem accelerator in view of transmission and lifetime

Optimum thickness of charge stripper foils installed at the terminal of a tandem accelerator has been investigated from the view of (1) charge stripping effect, (2) transmission of ions through accelerator, (3) lifetime of foils for the irradiation of ions. For this purpose, measurements have been done for (a) transmission of H, Li, O, Br and Au ions, passing through 12 UD Pelletron tandem accelerator for carbon stripper foils of 1.8–19.5 μg/cm² thickness, at terminal voltages of 5 and 10 MV, and (b) lifetime of 2–15 μg/cm² thick Tanashi foils developed by Sugai by irradiating Au ions at the terminal voltage of 10 MV. The results obtained are as follows: (a) From the view of above items (1) and (2), the optimum thickness of foils is 10 μg/cm² for ions of Z=1, several μg/cm² for Z=8, and less than a few μg/cm² for heavier ions. (b) From the view of item (3), the lifetime of Tanashi foils by means of new arc-discharge method is demonstrated to be much longer than that of commercial foils for foils thicker than about 5 μg/cm² thick. This superiority rapidly decreases with decreasing foil thickness, and at around 2 μg/cm², the lifetime of Tanashi foils is at the most 2.4 times longer than that of commercial foils.     

Hazardous impact of toxic metals on tobacco leaves grown in contaminated soil by ultrasonic assisted pseudo-digestion: multivariate study

Tobacco leaves (Nicotiana tabacum L.), agricultural soil and pollute irrigated lake water samples were collected during 2005–2006 and analyzed for Cd and Ni by electrothermal atomic absorption spectrometry (ETAAS). A simple and efficient procedure was investigated for the complete decomposition of tobacco leaves using ultrasonic assisted acid pseudo-digestion method (UPDM). A Plackett–Burman experimental design was used as a multivariate strategy for the evaluation of seven factors/variables at once, while central composite were used to found optimum values of significant variables. The accuracy of the proposed methods was assessed by analyzing certified reference (CRM); Virginia tobacco leaves (CTA-VTL-2). The results being compared with those obtained by conventional wet acid digestion method. The result obtained by optimized method showed good agreement with the certified values and sufficiently high recovery 97.8 and 98.7% for Cd and Ni, respectively. Under optimal conditions, the detection limits (3σ) were evaluated to be 0.019 μg g⁻¹ for Cd and 0.37 μg g⁻¹ for Ni. The proposed method was successfully applied to the determination of Cd and Ni in raw, processed tobacco and different branded cigarettes samples.