RP-HPLC测定烧仙草不同部位中的齐墩果酸和熊果酸

采用超声辅助提取,建立烧仙草不同部位中齐墩果酸和熊果酸的高效液相色谱分析方法.色谱柱为Kromasil C18柱(4.6mm×250mm,5μm),流动相为甲醇∶水∶磷酸(90 ∶ 10 ∶ 0.1,V/V/V),流速0.8mL·min-1,检测波长210nm,柱温30℃.齐墩果酸在0.228-2.850μg时,与峰面...     

Determination of Melphalan and Chlorambucil in Tablet Dosage form Using High-Performance Liquid Chromatography and Amperometric Detection

Abstract

We developed a liquid chromatographic method for the measurement of melphalan and chlorambucil in tablets, using a reversed phase C18 column with isocratic elution and amperometric detection. For melphalan the potential was set at +0.95V and chlorambucil at + 0.90V. The method is simple, sensitive and may also be applicable to pharmacokinetic studies.     

A hybrid structure gaseous detector for ion backflow suppression

A new concept for a hybrid structure gaseous detector module with ion backflow suppression for the time projection chamber in a future circular collider is presented.It is a hybrid structure cascaded Gas Electron Multiplier(GEM) with a Micromegas detector.Both Micromegas and GEM have the capability to naturally reduce most of the ions produced in the amplification region.The GEM also acts as the preamplifer device and increases gas gain together with the Micromegas.Feasibility tests of the hybrid detector are performed using an ~(55)Fe X-ray source.The energy resolution is better than 27% for 5.9 keV X-rays.It is demonstrated that a backflow ratio better than 0.2% can be reached in the hybrid readout structure at a gain of 5000.     

Gear fault diagnosis under non-stationary operating mode based on EMD,TKEO, and Shock Detector

Condition monitoring of gearboxes running under non-stationary operating conditions is a very difficult task. In this study, a signal processing technique is developed for damage detection of a bevel gearbox running under variable load and speed conditions. The proposed technique is applied on simulated vibration data computed through a dynamic model of bevel gearbox. The procedure used in this technique is based on the extraction of the shock related to the defect using the Shock Detector (SD) method. Firstly, vibration signals are decomposed into IMFs using Empirical Mode Decomposition (EMD). Then, the Teager–Kaiser Energy Operator (TKEO) is used to assess the instantaneous energy of the signal. Afterwards, SD is applied to examine and quantify the shock contents of the TKEO signal, which reflect the effect of the defect.     

Spontaneous excitation of a detector in circular motion coupled to massless Rarita–Schwinger fields in vacuum

We study the spontaneous excitation of a detector (modeled by a two-level atom) in circular motion coupled nonlinearly to vacuum massless Rarita–Schwinger fields in the ultrarelativistic limit and demonstrate that the spontaneous excitation occurs for ground-state atoms in circular motion in vacuum but the excitation rate is not of a pure thermal form as that of the atoms in linear uniform acceleration. An interesting feature is that terms of odd powers in acceleration appear in the excitation rate whereas in the linear acceleration case there are only terms of even powers present. On the other hand, what makes the present case unique in comparison to the atom’s coupling to other fields that are previously studied is the appearance of the terms proportional to the seventh and ninth powers of acceleration in the mean rate of change of atomic energy which are absent in the scalar, electromagnetic and Dirac field cases.     

相干场成像探测器噪声定量化占比模型

为解决激光相干场成像系统探测器噪声相对总噪声的定量化占比估计问题,分析探测器噪声是否为主要噪声源,提出一种探测器噪声占比权重定量化分析计算方法.基于光电子统计方法得到系统信噪比方程,并引入信噪比中间参数估计方程,建立了探测器噪声相对总噪声的占比权重定量化计算模型.结合理论分析与实验测量进行验证,结果表明:针对构建的相干场成像实验系统,探测器噪声占比权重达52%,进一步分析可知实验在大气相对宁静的夜晚进行,系统受背景光噪声和湍流噪声影响小,探测器噪声是主要噪声源.所提方法可有效估算探测器噪声占比权重,具有便捷、高效的特点,可用于实际相干场成像系统探测器噪声定量化评估测量分析.     

A Systematic Approach for the Evaluation of Triethanolamine as a Possible Sulfur Dioxide Sorption Detector Coating

Abstract

A change in the vibrating frequency of a quartz crystal can be an accurate measurement of the mass change on the surface of the crystal. When coated with an absorbing compound, the subsequent frequency change indicates the sorption of a chemical species by the coating. An approach is proposed for evaluating potential crystal coatings and is. applied to the evaluation of Triethanolamine as a possible sulfur dioxide sorption detector coating.     

Reply to comments on ‘The investigations on K and L X-ray fluorescence parameters of gold compounds'

We reply to comments raised in Kumar and Puri (2011). The comments claim that our results may ;be considered inconsequential because of the detector efficiency at Ge K-edge energy and the procedure of the photo-peak area evolution. However, to obtain detector efficiency in different energies, the variation of the factor I₀Gε as a function of the energy was drawn and the error arising from the detector efficiency added to our results. Moreover, the peak fitting procedure was made by the software program and the values of the reduced χ² and coefficient of determination show that the fits are quite adequate. Therefore, our results may be considered consequential.     

X-ray induced conductivity of ZnSe sensors at high temperatures

Measurements of intrinsic conductivity and X-ray induced conductivity were performed on specially undoped ZnSe samples. The measurements demonstrated that sensors made of ZnSe have minor intrinsic conductivity when heating up to the temperature of 180 °C, and significant X-ray induced conductivity. Dose dependence “dose rate - current” is described with simple power function which considerably simplifies calibration of sensors. This results can be used during the designing of high-temperature X-ray and gamma-radiation detectors for radiation hot rolling thickness gauges which are widely used in the metallurgy.