Multidimensional chromatography coupled with mass spectrometry for target-based screening

Summary The synthesis of structural analogs and the process of drug discovery have evolved dramatically through recent advances in solid-phase synthesis reagents and automated screening systems. As molecular diversity strategies emerge, the need for automated target-based selection of lead candidates becomes equally important. Multidimensional automated chromatographic techniques coupled to electrospray ionization mass spectrometry facilitate the selection process and provide maximum characterization information in a single screening run. The capture of tightly bound affinity leads by target biomolecules, followed by subsequent release and high-resolution separation with sensitive detection, significantly reduces the time required to identify and characterize lead compounds. This automated multidimensional chromatographic approach coupled with mass spectrometry, Selectronics, was used with several organic and natural libraries to demonstrate an automated target-based screening technique to select for high-affinity binders as potential lead compounds.Abbreviations ESI electrospray ionization - HPLC high-performance liquid chromatography - HTS high-throughput screening - ESI-TOF electrospray ionization time-of-flight - SAR structure-activity relationship     

Application of extraction induced by emulsion breaking for trace multi-element determination in jet fuel by inductively coupled plasma-mass spectrometry

ABSTRACT

A novel method, based on extraction induced by emulsion breaking, is proposed for rapid simultaneous determination of iron, manganese, copper, and zinc in jet fuel by inductively coupled plasma-mass spectrometry. Several parameters affecting the extraction efficiency were investigated including the concentrations of nitric acid and emulsifying agents, centrifugal speed, and extraction time. The limits of detection for iron, manganese, copper, and zinc were 0.116, 0.028, 0.06, and 0.085 µg L^?1, respectively. The accuracy of the method was tested by the analysis of spiked samples (recovery percentages between 90% and 107% were observed) and by comparison with a well-established method.     

电感耦合等离子体质谱法测定铜矿区20种植物中的金银

采用灰化-王水处理试样,选取103 Rh和203 Tl作为测定107 Ag、109 Ag和197 Au的内标元素,建立了电感耦合等离子体质谱法测定铜矿区栓皮栎等20种植物中金和银的方法。所建立方法用于不同矿区植物样品的分析,相对标准偏差(n=5)为9.05%～0.85%,加标回收率在93.6%～101.6%之间,Au和Ag检出限分别为0.048和1.06ng.g-1。该方法简便、准确,适用于铜矿区植物中金和银的测定。测定结果表明,矿区中金和银含量因不同植物而存在较大差异,变动范围为Au:0.18～0.99ng.g-1,Ag:282～2 150ng.g-1,其中凤尾蕨、芒萁和长叶实蕨中Ag具备地球化学异常特征,可作为找矿有效指示的植物。     

电感耦合等离子体质谱测定居住区大气中痕量铍、镉、砷、铅

建立电感耦合等离子体质谱法测定居住区大气中铍、镉、砷、铅等痕量元素的分析方法.通过超声浸提同时分离气溶胶样品中多种元素,对仪器工作参数进行优化,选取72Ge,115In和204T1作为测定元素的校正内标,有效克服了基体效应、接口效应和仪器漂移对测定信号产生的影响.测定元素标准曲线的相关系数均优于0.999 5,铍、镉、砷、铅各元素的测定方法检出限分别为0.022,0.020,0.018和0.130μg·L-1,方法定最限分别为0.102,0.093,0.083和0.602 ng·m-3.通过测定标准参考物质GBW(E)080212考察方法的准确性,测定值均在标准值范围内.取采样滤膜分别加入低、中、高浓度标准溶液进行测定,样品加标回收率为91.6%～109.7%,相对标准偏差介于0.7%～4.8%.该方法精密度好、准确性好,简便、快速、灵敏,适用于居住区大气中痕量元素铍、镉、砷、铅含量的测定.     

电感耦合等离子体质谱法测定饮用水中6种痕量重金属元素

采用电感耦合等离子体质谱(ICP-MS)法同时测定饮用水中的镉、铬、铅、锌、铜、镍6种元素的含量.对仪器工作参数进行了优化,选取45Sc,72Ge,115In, 209Bi作为测定元素的内标元素,有效克服了基体效应、接口效应及仪器波动所产生的影响,利用八极杆碰撞/反应池技术,消除多原子离子对待测元素的干扰.测定元素校准曲线的相关系数都在0.999 7以上,各元素的检出限在0.70～77.0 ng·L-1之间,相对标准偏差(RSD)介于0.47%～1.69%之间.测定标准参考物GBW08607,测定值均在标准值范围内.对4个地区的饮用水进行了检测,样品加标回收率为92%～108%.该方法具有简便、快速、准确、稳定的特点,可作为饮用水中痕量元素检测的可靠方法.     

紫外告警系统探测距离的估算

介绍了紫外告警原理及紫外告警系统的结构组成。基于典型目标(导弹)的紫外辐射特征和紫外辐射的大气传输特性,结合紫外告警系统探测器件的性能参数,根据像平面照度公式,提出了紫外告警系统探测距离的估算方法及模型,实例计算并验证了紫外告警系统在不同观察方位角对固体推进剂导弹的探测距离。分析研究表明,改变CCD最小照度值,像管的增益,光学系统的透过率和相对孔径等探测传感器的性能参数,可以提高紫外告警系统的探测距离。     

全向激光告警系统中SWIRFPA的盲元补偿算法

针对全向激光告警系统中SWIRFPA的盲元补偿问题,提出一种基于邻域灰度特性的加权插值盲元补偿算法.阐述该算法的基本思想和原理,根据盲元邻域灰度值的分布情况,赋予每个邻域像元与其灰度值相关的权重,进而完成盲元补偿.从主客观2个角度对补偿效果进行评价.结果表明:与传统的邻域平均法和中值滤波法相比,加权插值盲元补偿算法对全向激光告警系统中SWIRFPA的盲元补偿效果最好,不仅使盲元补偿值与其邻域偏差最小,而且减小了盲元对系统探测的影响,有效提高了系统性能.     

放电功率变化对电磁波在电感耦合闭式等离子体中的衰减特性

射频电感耦合等离子体(ICP)放电方式能够在较宽的压强范围内产生大面积、密度高的等离子体,在对电磁波衰减应用中具有较大优势。通过研究ICP等离子体与电磁波相互作用的过程,改进闭式等离子体模型,建立电磁波在非均匀等离子体中传播的分层计算模型,对实测诊断分布情形下等离子体与电磁波的相互作用进行研究,得到不同功率条件下电磁波衰减的变化情况;提出射频电感耦合闭式等离子体用于电磁波衰减的方法并实验验证,基于等离子体覆盖金属平板的测量模型,在实验室内搭建了以金属板为衬底的弓形微波反射测试系统,研究了闭式等离子体对4～8 GHz频段范围内微波反射的作用特性,以及不同射频功率对微波反射的影响规律,并将实验测量与计算结果进行对比分析。实验表明,通过功率调节,电感耦合闭式等离子体对5.92～6.8 GHz频带电磁波具有明显的衰减作用。     

An attractive analytical technique for coupled system of fractional partial differential equations in shallow water waves with conformable derivative

Mathematical simulation of nonlinear physical and abstract systems is a very vital process for predicting the solution behavior of fractional partial differential equations(FPDEs)corresponding to different applications in science and engineering. In this paper, an attractive reliable analytical technique, the conformable residual power series, is implemented for constructing approximate series solutions for a class of nonlinear coupled FPDEs arising in fluid mechanics and fluid flow, which are often designed to demonstrate the behavior of weakly nonlinear and long waves and describe the interaction of shallow water waves. In the proposed technique the n-truncated representation is substituted into the original system and it is assumed the(n-1) conformable derivative of the residuum is zero. This allows us to estimate coefficients of truncation and successively add the subordinate terms in the multiple fractional power series with a rapidly convergent form. The influence, capacity, and feasibility of the presented approach are verified by testing some real-world applications. Finally, highlights and some closing comments are attached.     

Simulation of earth background radiation characteristic for satellite borne laser warning system

The earth background radiation is a kind of main background interference for satellite borne laser warning system in the space environment, and it is so necessary that the radiation characteristic be studied. In this paper, the mathematic model of the earth background radiation is established, the input parameters of 6S model are analyzed and set, and the simulation of earth background radiation is carried on aiming at the alarm wavelength 1.315 μm and the waveband 0.9-1.7 μm which is the responsive bandwidth of the detector. The results show that: with the increase of zenith angle, the irradiance from ground reflection increases, but the irradiances of atmospheric path radiation and surface-atmosphere interaction at the satellite level decrease; comparing with other two parts, the irradiance from ground reflection weighs most, and the corresponding percentages for 1.315 μm and 0.9-1.7 μm are 75.89% and 73.99%, respectively. The total irradiance at the satellite level from earth background radiation has exceeded the detection sensitivity of the system (about 1 mW/cm²), which may arouse the false alarm. So, the special technique of background suppression must be studied.     

Microfluidic chip-inductively coupled plasma mass spectrometry for trace elements and their species analysis in cells

Abstract

Accurate identification and quantification of trace elements and their species in cells is an important prerequisite for the exploration of their physiological function and related mechanisms of process involving trace elements/species in human body. Inductively coupled plasma mass spectrometry (ICP-MS) is a powerful analytical instrument for trace elements detection, while it still suffers from insufficient limits of detection, interference from complex cell matrix, and incompatible sample consumption in cells analysis. Microfluidic chips which possess advantages of low sample/reagent consumption, rapid analysis speed and high spatial resolution provide perfect miniaturized and integrated platforms for cell analysis. In this article, microfluidic chip-ICP-MS techniques for trace elements and their species analysis in cells were reviewed. Both chip-based pretreatment techniques (e.g., magnetic solid phase microextraction (MSPME), monolithic capillary microextraction (MCME), liquid phase microextraction (LPME)) including chip-based array microextraction techniques for trace elements and their species analysis and droplet chip for single cell analysis were introduced. The newly developed methods of microfluidic chips in combination with ICP-MS for trace elements and their species analysis in small numbers of cells and even single cell were critically discussed, including chip-based MSPME/MCME/LPME-(electrothermal vaporization-ICP-)MS, on-line chip-based array MSPME/MCME-ICP-MS, on-line chip-based array MSPME-high performance liquid chromatography-ICP-MS and online droplet chip-time-resolved ICP-MS. These methodologies were demonstrated with high sensitivity, high throughput, good matrix resistance and low sample/reagent consumption, contributing to the quantification of trace elements/species in cells and even single cells. Relevant 20 references are included herein, and the development trend of microfluidic chip-ICP-MS techniques for cells analysis is prospected.     

Effect of the matrix in mass spectrometry using an inductively coupled plasma

Using different types of devices, we have performed an experimental study of matrix ionization effects manifesting themselves in the method of mass spectrometry with an inductively coupled plasma. Basic laws governing these effects have been established. The composition of the analytical zone of the plasma and possible attenuation of the signal from the analyte on introduction of a matrix element due to processes occurring in the plasma and in the ion beam have been determined theoretically. A high degree of coincidence between experimental and calculated results is shown. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 65, No. 5, pp. 768–774, September–October, 1998.     

Stochastic model for the dynamics of a spin-oscillator coupled system

For a model system consisting of bilinearly coupled harmonic oscillators and pseudospins, a generalized Langevin equation for the oscillator subsystem, valid for general spatial dimensionality and interaction range, is derived exactly, using Mori's projection operator technique. The retarded friction kernel is derived to second order in the spinoscillator interaction constant. It is shown that for a one-dimensional model system treated in an earlier paper, the oscillator susceptibility predicted by this approximation, is identical to the susceptibility obtained then by a phenomenological Langevin equation approach.     

原子与耦合腔相互作用的动力学特性

研究了两个二能级原子分别与耦合腔A和B发生共振相互作用时的情况,给出了总激发数为1时系统态矢的演化。通过对原子1和原子2占有激发子的几率,以及腔A和腔B具有1个光子的几率计算,研究了系统的动力学行为。讨论了腔场间的耦合强度变化对系统动力学行为的影响。研究结果表明:随着腔场间耦合的增强,系统初始的激发子分布在原子1和原子2中的几率增大,腔A和腔B具有1个光子的几率减小,两原子间的纠缠增强。     

Enhancement and weakening of stochastic resonance for a coupled system

In the paper, we investigate the phenomenon of stochastic resonance of a system with finite locally coupled linear elements driven by multiplicative dichotomous noise and temporal periodic signal. It is shown that, for some suitably selected values of the parameters, with increasing the size of the system or the coupling among the nearest elements, the stochastic resonance phenomenon can be enhanced; while for some other suitably selected parameters' values, with the increase of the size or the coupling, the phenomenon of stochastic resonance can be weakened. Our results can provide some useful insights for the investigation of the stochastic resonance phenomenon of the systems with locally (or globally) coupled finite (or infinite) elements.     

Stochastic model for the dynamics of a spin-oscillator coupled system

We construct a stochastic model for the dynamics of a one-dimensional system consisting of bilinearly coupled harmonic oscillators and spins. The spin dynamics is defined as a Glauber model where the spins are effectively coupled through their interaction with the oscillators. To maintain internal thermal equilibrium in the composite system, which does not exhibit Onsager symmetry, we introduce a phenomenological retarded friction in the oscillator equation of motion and relate it to the spin correlation function through a fluctuation-dissipation theorem. The oscillator susceptibility is derived and the behavior of its poles as functions of wavevector and temperature is studied. The results are compared to those obtained by other authors who have studied similar systems, using irreversible thermodynamics. In contrast to ours, these treatments do not give an explicit result for the wavevector dependence of the poles.     

Solitons in a system of coupled graphene waveguides

Propagation of extremely-short optical pulses that can be considered as discrete solitons in a system of graphene waveguides has been studied. The effective equation having the form of an analog of the classical sin-Gordon equation has been derived. The effects observed with varying the initial pulse width have been investigated