One-dimensional $\mathcal{PT}$-symmetric acoustic heterostructure

The explorations of parity-time ($\mathcal{PT}$)-symmetric acoustics have resided at the frontier in physics, and the pre-existing accessing of exceptional points typically depends on Fabry-Perot resonances of the coupling interlayer sandwiched between balanced gain and loss components. Nevertheless, the concise $\mathcal{PT}$-symmetric acoustic heterostructure, eliminating extra interactions caused by the interlayer, has not been researched in depth. Here we derive the generalized unitary relation for one-dimensional (1D) $\mathcal{PT}$-symmetric heterostructure of arbitrary complexity, and demonstrate four disparate patterns of anisotropic transmission resonances (ATRs) accompanied by corresponding spontaneous phase transitions. As a special case of ATR, the occasional bidirectional transmission resonance reconsolidates the ATR frequencies that split when waves incident from opposite directions, whose spatial profiles distinguish from a unitary structure. The derived theoretical relation can serve as a predominant signature for the presence of $\mathcal{PT}$ symmetry and $\mathcal{PT}$-symmetry-breaking transition, which may provide substantial support for the development of prototype devices with asymmetric acoustic responses.     

二乙基二硫代氨基甲酸银光度法测定磷矿石中砷

近年来,随着我国磷矿石出口量的逐年增加,国外用户对磷矿石的质量要求也逐年提高,合同中加入了对铅、砷、汞等一些微量有害元素的限制。本法参照国家标准方法采用银盐法测定磷矿石中微量砷,并使用500g·L^-1柠檬酸溶液取代了原标准中使用的酒石酸溶液作掩蔽剂,有效地消除了磷矿石中Fe^3＋、Hg^2＋等共存离子的干扰。该法用于磷矿石中砷含量的测定,取得较满意的结果。     

纳米级普鲁士蓝的制备表征及其在电分析化学中的应用

普鲁士蓝(PB)可以作为许多生物化学物质的人工酶来修饰惰性电极,用来催化它们的氧化还原.该文评述了近年来国内外对纳米尺度PB在电分析化学领域中的应用进展,含纳米PB的基本特性、制备方法、电极固定,以及在电分析化学中的应用.纳米PB对检测信号有放大作用,已经在电分析中体现了它的优越性,对纳米PB的深入研究将开发出性能更优良的传感器.