Calibration method for determination of acids and bases with piezoelectric quartz crystal sensors

Based on the linear relation between the frequency response of the piezoelectric quartz crystal sensor and the conductivity of the solution to be measured, calibration models for quantitative analysis of acid and base systems are derived and are verified both theoretically and experimentally. Then quantitative determinations of aspirin and penicilline were done with the calibration technique. The quantitative analysis results of the two true pharmaceutical systems indicate that the models, combining linear regression, can give precise and accurate concentration estimates, which can reduce the influence of the presence of interferences.     

Miniaturized back-side contact transducer for potentiometric sensors

A novel type of a miniature transducer for potentiometric sensors was designed and tested. The transducer is made from an ordinary printed circuit board using a typical technology. As a result, a back-side contact structure was obtained, which can be mounted in flow systems. The advantage of the fabrication process is its cheapness and flexibility in designing modified structures. The measurement properties of the transducer were tested as a chloride sensor. Then the structure was covered with polyHEMA and a potassium-selective membrane and tested as a potassium sensor. The performance and the long-term stability of the sensors with plasticized PVC and Siloprene based potassium-selective membranes were compared.     

Expanded aromatic carboxylate anion induced molecular sandwich construction via a tetracationic imidazolium macrocycle conversion from molecular box to molecular tweezer

The molecular box, namely cyclo[2](2,6-di(1H-imidazol-1-yl)pyridine)-[2](1,4-dimethylene benzene) (1⁴⁺; as PF₆^? salt), fold its conformation as molecular tweezer to clip the specific carboxylates with expanded aromatic plane. The binding modes between 1⁴⁺ and carboxylate, namely pseudorotaxane, outside or clipping (i.e., sandwich like), also depend on the location of carboxylate on the large conjugated moiety. These finding develop the usability of 1⁴⁺ and carboxylates as important building block pairs to create non-covalent self-assembly structures.     

A novel polyoxometalate chain constructed from sandwich lanthanide-containing polyanions [Pr(PW<Subscript>11</Subscript>O<Subscript>39</Subscript>)<Subscript>2</Subscript>]<Superscript>11−</Superscript> and sodium cation linkers

A novel sandwich-type lanthanide polyoxometalate [(CH₃)₄NH]₄Na₃[Pr(PW₁₁O₃₉)₂] · 12H₂O (1) has been synthesized by conventional method and characterized by cyclic voltammetry, IR spectroscopy and single crystal X-ray diffraction. X-ray diffraction result reveals that the sandwich type polyanions are linked by sodium cations to form a structure of zigzag chains, and the chains are further connected into an extensive two-dimensional (2D) framework depending on hydrogen bond. The emission spectrum result shows weak photoluminescence of compound 1. The magnetic studies of compound 1 demonstrate an antiferromagnetic interaction in 1.     

Resonant characteristics of PZT-4 transducers for photoacoustic signal detection

Rectangular and circular types of PZT-4 transducers have been studied. Their resonant frequencies were determined in different media and related to the photoacoustic signal generation. Recommendations were made for maximum signal detection with these transducers.     

A piezoelectric stress gauge for measuring dynamic stress in soil and rock media

A piezoelectric stress gauge is described in this paper. Its major performance data are: measuring range 10⁶–10⁸ Pa, response time less than 7μs; non-linearity within ±1% and total stress measurement error within ± 10%. It can be used for measuring dynamic stress in soil, rock and concrete media as well as dynamic force and dynamic pressure in fluids.     

Hg2Br2声光器件的换能器带宽和镀层厚度的确定

提出用环氧树脂聚合物作为换能器与Hg2Br2声光介质的缓冲层(粘接层),设计Hg2Br2声光器件的换能器。根据换能器等效电路网络分析法,就x切LN／Hg2Br2声光器件的电极层各种金属材料和厚度计算了换能器损耗TL随规一化频率f／fo的变化关系。从声光器件的布喇格带宽和工艺条件出发,优化选择了换能器损耗为3dB范围内的换能器结构、电极层材料及其厚度和压电层厚度,并确保了换能器的倍频程带宽。     

Quantum Fluctuations of the Current and Voltage in Thermal Vacuum State for Mesoscopic Quartz Piezoelectric Crystal

The mesoscopic quartz piezoelectric crystal equivalent circuit is quantized by the method of damped harmonic oscillator quantization. It is shown that, when each branch is in the thermal vacuum states, the quantum fluctuations of the voltage, and current of each loop relate with not only the equivalent circuit inherent parameter, but also the temperature and decay according to exponent along with time.     

线性双折射对光纤电流互感器影响的研究

应用琼斯矩阵理论分析传感光纤中残余线性双折射对光纤电流互感器测量精度的影响。根据干涉结果得到在传感光纤中加入大量圆双折射可以抑制残余线性双折射,并提出有效的减小线性双折射误差的方法。     

超声换能器带宽对光声成像的影响

研究了不同尺寸吸收体产生的光声压的频谱特性：对于厘米量级、毫米量级和几百个微米量级的吸收体,产生光声压频谱的主要范围分别约为20～300kHz、70kHz～2．5MHz和400kHz～20MHz;讨论了不同频率范围的光声信号对重建图像的影响,低频段的光声信号能反映物体的非边界区域,而高频段的光声信号能突出物体的细微结构,尤其是物体的边界特征。提出了不同尺寸的吸收体要选用或设计不同带宽范围的探测器进行检测的方法．当探测器的带宽范围与光声压频谱范围基本吻合时,损失的频率成份较少,重建的光声图像效果较好,这一结论在仿真和实验结果中都得到了证明。实验用的光源为YAG激光器,波长为532nm,重复频率为30Hz,脉宽为7ns,探测器为针状的PVDF膜水听器,接收面积的直径为1mm。