In this work a self-referencing fiber optic intensity sensor using virtual instrumentation is presented. To ensure higher flexibility and dynamic optimization, the use of an optical fiber delay line or an electrical delay line is avoided by implementing a delay line in the virtual domain, preserving the self-referencing and sensitivity characteristics of the proposed optical intensity sensing structure. Results are presented where displacement is measured with an 18 μm resolution demonstrating the concept feasibility. 相似文献
Metabolomics is the comprehensive assessment of endogenous metabolites of a biological system. These large-scale analyses of metabolites are intimately bound to advancements in ultra-performance liquid chromatography-electrospray (UPLC) technologies and have emerged in parallel with the development of novel mass analyzers and hyphenated techniques. Recently, the combination of UPLC with MS covers a number of polar metabolites, thus enlarging the number of detected analytes in the widely used separation sciences. This technology has rapidly been accepted by the analytical community and is being gradually applied to various fields such as metabolomics and traditional Chinese medicine (TCM). Given the power of the technology, metabolomics has become increasingly popular in drug development, molecular medicine, traditional medicine and other biotechnology fields, since it profiles directly the phenotype and changes thereof in contrast to other "-omics" technologies. Hyphenated UPLC/MS technique is becoming a useful tool in the study of body fluids, represents a promising hyphenated microseparation platform in metabolomics and has a strong potential to contribute to disease diagnosis. This review describes the applications of UPLC/MS in metabolomic research, and comparison role of HPLC/MS, NMR and GC/MS, highlights its advantages and limitations with certain characteristic examples in the life and TCM sciences. 相似文献
Multivariate curve resolution-particle swarm optimization (MCR-PSO) algorithm is proposed to exploit pure chromatographic and spectroscopic information from multi-component hyphenated chromatographic signals. This new MCR method is based on rotation of mathematically unique PCA solutions into the chemically meaningful MCR solutions. To obtain a proper rotation matrix, an objective function based on non-fulfillment of constraints is defined and is optimized using particle swarm optimization (PSO) algorithm. Initial values of rotation matrix are calculated using local rank analysis and heuristic evolving latent projection (HELP) method. The ability of MCR-PSO in resolving the chromatographic data is evaluated using simulated gas chromatography–mass spectrometry (GC–MS) and high-performance liquid chromatography–diode array detection (HPLC–DAD) data. To present a comprehensive study, different number of components and various levels of noise under proper constraints of non-negativity, unimodality and spectral normalization are considered. Calculation of the extent of rotational ambiguity in MCR solutions for different chromatographic systems using MCR-BANDS method showed that MCR-PSO solutions are always in the range of feasible solutions like true solutions. In addition, the performance of MCR-PSO is compared with other popular MCR methods of multivariate curve resolution-objective function minimization (MCR-FMIN) and multivariate curve resolution-alternating least squares (MCR-ALS). The results showed that MCR-PSO solutions are rather similar or better (in some cases) than other MCR methods in terms of statistical parameters. Finally MCR-PSO is successfully applied in the resolution of real GC–MS data. It should be pointed out that in addition to multivariate resolution of hyphenated chromatographic signals, MCR-PSO algorithm can be straightforwardly applied to other types of separation, spectroscopic and electrochemical data. 相似文献
In this paper we discuss the progress at Argonne National Laboratory with the APosS. We outline possible improvements that can increase the flux of positrons by increasing the electron current on target or by modification of the positron converter. We discuss some new techniques that could increase moderation efficiency and thus further increase positron flux two to three orders of magnitude by making use of modern accelerator techniques. 相似文献
In the framework of the SPES project at LNL-INFN a method for emissivity measurements by a double-frequency pyrometer in the
infrared region at high temperatures on opaque gray bodies of SiC and graphite is presented. The measurement method proposed
in this work reveals a good fitting with literature values. Moreover, the effect of surface finishing on emissivity values
has been investigated. 相似文献
Determinations of radical density are essential to investigate the
physical-chemical processes in plasmas and setup the related theoretical
models. This paper presents the experimental measurement of atomic hydrogen
near grounded electrode in dielectric barrier discharge medium-pressure
hydrogen plasma via threshold ionisation-molecular beam mass spectrometry.
After investigating the possible influences from parent molecules in excited
states, background component and space-charge, evolution of atomic hydrogen
density as functions of discharge parameters are investigated utilising the
signal of H2 molecule beam as the reference. At fixed gas pressure of
6.0 torr and a discharge voltage of 24 kV, atomic hydrogen density increases
monotonously from 1.1×1014 to 2.0×1015 cm-3
as the discharge frequency increases from 9 to 26 kHz. Similarly the rising
discharge voltage also lead to enhancement of atomic hydrogen density. 相似文献
Broadband femtosecond-laser frequency combs are filtered to spectrographically resolvable frequency-mode spacing, and limitations
of using cavities for spectral filtering are considered. Data and theory are used to show implications relevant to spectrographic
calibration of high-resolution, astronomical spectrometers. 相似文献
Spatial distribution of delayed responses of argon and hydrogen spectral line and continuum intensity to square power modulation
was investigated in order to get better insight into the processes occurring in argon dc arc plasma. The power was abruptly
changed between stationary values, 9 and 3.5 A. For these currents steady state radial distributions of electron number density,
temperature and emission intensity were measured. On part of the discharge radial profiles the power drop and the power jump
are both accompanied by intensity peaks which may be explained by displacement of the arc core axis and change in the arc
core diameter during the power modulation. 相似文献
Starting in biochemistry and pharmaceutical chemistry, combinatorial methods, automated synthesis and high‐throughput characterization are being further developed for organic synthesis and polymer research. The development is strongly driven by the achievements in biochemistry and pharmaceutical chemistry and the need to minimize the time‐to‐market for novel polymeric products. The success of high‐throughput methodologies in polymer science is partially limited by the commercially available hardware (synthesizers, workstations, robots, online‐characterization instruments, etc.) and software. A short overview of commercially available equipment for polymer research is provided in this Review.