Tuning the phase separation in La_(0.325)Pr_(0.3)Ca_(0.375)MnO_3 using the electric double-layer field effect

Electric double-layer field effect experiments were performed on ultrathin films of La0.325Pr0.3Ca0.375MnO3, which is noted for its micrometer-scale phase separation. A clear change of resistance up to 220% was observed and the characteristic metal–insulator transition temperature TPwas also shifted. The changes of both the resistance and TPsuggest that the electric field induced not only tuning of the carrier density but also rebalancing of the phase separation states. The change of the charge-ordered insulating phase fraction was estimated to be temperature dependent, and a maximum of 16% was achieved in the phase separation regime. This tuning effect was partially irreversible, which might be due to an oxygen vacancy migration that is driven by the huge applied electric field.     

A key to the storage stability of Au/TiO(2) catalyst

The effect of Au(3+) percentage in Au/TiO(2) on its storage stability at room temperature was studied by varying the drying temperature and storage duration of a deposition-precipitation prepared Au/TiO(2) sample. Carefully-designed room temperature storage in a desiccator, in the dark to exclude any interference of light irradiation, was referenced to the freezing storage (255 K) in a refrigerator. The samples were characterized by well-calibrated H(2)-TPR, TEM and TG measurements. Reduction of Au(3+) ions and agglomeration of metallic Au particles were shown to be the main reasons for the deterioration of Au/TiO(2) during desiccator-storage. Correlating the percentage of Au(3+) ions, determined by H(2)-TPR, with the storage stability of Au/TiO(2) for CO oxidation at 273 K revealed that Au/TiO(2) samples with higher Au(3+) percentages (>90%) were much more stable during the desiccator-storage than those with higher percentages of metallic Au. Residual water in fresh Au/TiO(2) before storage showed a promotional effect on gold reduction and agglomeration during storage. By maximizing the percentage of Au(3+) ions and minimizing the residual water in the fresh sample, the deterioration of the Au/TiO(2) catalyst was successfully avoided during desiccator-storage of up to 150 days in dark. A possible mechanism of Au/TiO(2) deterioration during the desiccator-storage was also discussed.     

Flux qubit with a large loop size and tunable Josephson junctions

We present the design of a superconducting flux qubit with a large loop inductance. The large loop inductance is desirable for coupling between qubits. The loop is configured into a gradiometer form that could reduce the interference from environmental magnetic noise. A combined Josephson junction, i.e., a DC-SQUID is used to replace the small Josephson junction in the usual 3-JJ (Josephaon junction) flux qubit, leading to a tunable energy gap by using an independent external flux line. We perform numerical calculations to investigate the dependence of the energy gap on qubit parameters such as junction capacitance, critical current, loop inductance, and the ratio of junction energy between small and large junctions in the flux qubit. We suggest a range of values for the parameters.     

应用表面增强拉曼光谱技术快速检测尿样中的β-兴奋剂

应用表面增强拉曼光谱技术与化学计量法相结合分析克伦特罗、沙丁胺醇和莱克多巴胺3种β-兴奋剂的标准溶液.在取自10头猪的尿样中,分别添加5个不同浓度的莱克多巴胺(1～20 mg/L),采用快速的液液萃取法对样品进行前处理,再进行表面增强拉曼测试.结果表明,克伦特罗和沙丁胺醇标准溶液的最低检测浓度为2 μg/L,莱克多巴胺标准溶液的最低检测浓度为0.1 mg/L;通过偏最小二乘法建立模型进行定量分析,3种药物的实际值与预测值的相关系数(R2)为0.9134～0.9368;本方法可检测尿样中1 mg/L莱克多巴胺,经外部验证后模型的实际值与预测值的相关系数(R2)为0 881,相对分析误差(RPD)为2.83;分析尿液中的莱克多巴胺含量所需时间小于30 min,为快速检测莱克多巴胺提供新途径.