A simple and robust liquid chromatography tandem mass spectrometry assay for determination of plasma free metanephrines and its application to routine clinical testing for diagnosis of pheochromocytoma

Plasma free metanephrines (PFMs) have high sensitivity for detecting pheochromocytoma (PCC). Herein, we developed a simple and reliable liquid chromatography tandem mass spectrometry assay for PFMs determination in Chinese population. PFMs were enriched by SPE without requiring extract evaporation or the use of buffers containing nonvolatile salts. The analytes were analyzed in multiple reaction monitoring mode. Inter‐ and intra‐assay precisions were ≤4.3% and ≤ 6.3%. The lower limits of quantification were 0.07 nmol/L for metanephrine and 0.06 nmol/L for normetanephrine. Recoveries of PFMs were in the range of 89.3–113%. The method was free from significant matrix effect, carryover and interference. Owing to its fast analysis time, more than 150 samples/day could be easily performed by a single operator. With the established reference intervals of PFMs in the Chinese population, this simple and robust LC–MS/MS method could be valuable for use in routine clinical laboratories. It is noted that the combined tests of PFMs with urinary catecholamines or urinary vanillylmandelic acid could improve specificity.     

Effect of magnetic field on sodium arsenate metastable zone width and crystal nucleation kinetics for crystallization

Sodium arsenate, the main component of arsenic-containing solid waste pollutants, causes serious environmental health threats. Crystallization is one of the effective methods for separating and purifying sodium arsenate from arsenic-alkali residue lixivium. However, the crystallization process is limited for its low observability and the lack of separation and purification data. In this work, a laser detection system with a magnetic field generator was designed, and the solubility, metastable zone width, interfacial tension, interfacial entropy factor, crystal nucleation, and growth rate of sodium arsenate were investigated in a constant composition environment. The results showed that the solubility, metastable zone width, interfacial tension, and interfacial entropy factor decreases with the presence of a magnetic field. The magnetic field shortened the crystallization induction time and changed the nucleation and growth rate of sodium arsenate. Under the magnetic field, the nucleation rate increased from 2.43 × 10¹⁶ to 8.98 × 10¹⁷ (s m³)⁻¹, and the growth rate decreased from 4.94 × 10⁻⁸ to 2.73 × 10⁻⁸ (s m³)⁻¹, the growth mechanism of sodium arsenate as a continuous growth mode was unchanged. In addition, the X-ray diffraction and infrared showed that the crystal structure of sodium arsenate is unaffected by the magnetic field, indicating that the enhancement of the crystallization process of sodium arsenate with the magnetic field could be a feasible method in engineering application.     

High Channel Count, Low Cost, Multiplexed FBG Sensor Systems

With rich products development experience in WDM telecommunication networks, we introduce a few of high channel count, multiplexed FBG fiber optic sensor systems featured in reliable high performance and low cost.     

Simplified Fast Transient Control in Coolerless Pump EDFA for Metro Applications

A novel optical transient suppression technique to dramatically reduce gain variation of EDFA with un-cooled pump is demonstrated experimentally, showing excellent performance of 50μs transient time with no more than 0.5dB excursion and 0.25dB offset.     

A modified continuous flow microcalorimeter for measuring heat dissipation by mammalian cells in batch culture

Microcalorimeters to monitor the heat dissipation of bench-scale animal cell cultures on line and in real time require a continuous circuit between the vessel measuring heat flow rate and the bioreactor. The modifications to the transmission lines and calorimetric heat exchanger were to: (i) reverse the usual upward direction of the cell suspension in the flow vessel to downwards; (ii) install an in situ washing/cleaning facility; (iii) use low diffusivity PEEK material; and (iv) maintain thermal equilibration by water-jacketing the transmission tubing. Chemical calibration showed that there was more than a 20% difference between the physical volume and the effective thermal volume. An appropriate thermodynamic system was defined in order to permit enthalpy balance studies.We are indebted to the BBSR.C (UK) for financial support under grant No. 2/3680. Mr. R.L. Taylor (ThermoMetric Ltd, Northwich, Cheshire) has been extremely helpful in discussions about the various designs.     

两路高功率钕玻璃激光系统

建立了脉宽１～２ｎｓ、能量８０Ｊ的两路钕玻璃激光系统，介绍了激光装置中的一些技术问题。     

脉冲激光制备薄膜材料的烧蚀机理

研究了脉冲激光烧蚀靶材的整个过程.从包含热源项的导热方程出发，利用适当的动态边界条件，详细研究了靶材在熔融前后的温度分布规律，并且给出了熔融后的固、液分界面的变化规律.熔融后的温度演化规律和固液相界面均以解析表达式的形式给出.还根据能量平衡原理给出烧蚀面位置随时间的变化规律.以硅靶材为例计算模拟了激光烧蚀的整个过程，与实验结果符合较好. 关键词： 脉冲激光 烧蚀面 熔融 温度演化     

附认股权公司债价值分析

附认股权公司债是公司债附有认股权证的新型金融产品．本介绍了附认股权公司债的定义；给出了附认股权公司债的定价模型，并给出了仿真案例．     

扰动情况下一类混沌系统的观测器同步

研究了存在外界扰动情况下一类混沌系统的同步问题，混沌系统非线性项无需满足输出反馈形式.首先对系统进行变换得到未受扰降价混沌系统，然后基于非线性观测器的思想构造同步观测系统实现了混沌同步，通过仿真证实了该方法的有效性. 关键词： 混沌系统 同步 观测器