Online Analysis Method Research Articles

Preliminary study on aerosol particle addition calibration method for on-line quantitative analysis of airborne radioactive particles with ICP-MS

An ambient aerosol concentration enrichment system coupled with ICP-MS for real-time monitoring of airborne radioactive particles is now under development. ICP-MS is very sensitive to sample introduction conditions, so it is necessary to develop an easy-use calibration method for on-line quantitative analysis in field application. In this paper, a calibration method using standard solution instead of monodisperse particles was established and validated preliminarily. First of all, four parameters for the method were determined experimentally, including: uptake flow rate and nebulisation efficiency of the Microconcentric nebuliser, nebulisation/transport efficiency of Aridus Desolvating Sample Introduction System, and Relative Sensitivity Factor between 159 Tb and 174 Yb. Then, monodisperse terbium nitrate particles were generated by a commercial Vibrating Orifice Aerosol Generator. Continuous aerosols of ytterbium nitrate droplets were nebulised from standard solution. They were mixed together, desolvated through the membrane dryer and introduced into ICP-MS for on-line analysis of terbium nitrate particles. The air sampled from nuclear environment was also introduced into ICP-MS to investigate the effect of flow rate on instrument responses. Finally, atom numbers of 159 Tb in discrete terbium nitrate particles were determined using the calibration method and compared to the calculated value. Results show that when air flow rate increase from 10 mL min−1 to 100 mL min−1, the ratio of 159 Tb ion count to 174 Yb ion intensity keeps constant although instrument sensitivity decreases by a factor of 25. The relative standard deviation of 159 Tb atom number measured is better than 18%. The discrepancy with the calculated value could be attributed to the over-estimation of atom number in the particles generated by VOAG because there was some liquid leakage in the VOAG.

Tie-line constrained distributed state estimation

This paper presents an implementable distributed state estimation method for online analysis of power systems having multiple, geographically separated areas. Distributed state estimation apart from giving a faster solution, also improves the condition number of the resultant gain matrices. The method proposed here uses the conventional WLS estimator (Gauss–Newton method) with equality constraints forcing the tie line flows as calculated by the adjacent areas to be equal. Based on the topology of the network, the system is partitioned into multiple areas and a processor is assigned to each of these areas for solving the local state estimation problem. Simulations carried out on the IEEE 14, 30 and 118 bus systems show good convergence properties and improvement on the condition number of the gain matrices when compared with centralized algorithms.

On-line high-performance liquid chromatography–diode array detection–electrospray ionization–mass spectrometry–chemiluminescence assay of radical scavengers in Epimedium

An on-line analysis method for the simultaneous detection and identification of radical scavenging compounds in plant extracts was developed by combining HPLC with hydrogen dioxide radical scavenging and HPLC–DAD–MS–CL system. The structural identification and activity characteristics of various constituents could be rapidly achieved by the on-line assay of UV, MS and CL in one run. In 4 species of Epimedium studied 32 compounds, including phenolic acids, 8-isopentenyl-flavonoid glycosides and flavonoid glycosides containing a ortho-hydroxyl group, were identified by comparison with authentic standards and published mass data. Among these compounds, phenolic acids and flavonoid glycosides containing an ortho-hydroxyl group could obviously inhibit CL, which suggested their strong radical scavenging activity. These four species each exhibited different active properties, which might correlate to their respective quality. The results indicated that the on-line HPLC–DAD–MS–CL system would be a potential method to rapidly and sensitively screen radical scavengers in herbal medicines, and could display an integrated fingerprint based on different detectors.

A web-based platform for rice microarray annotation and data analysis

Rice (Oryza sativa) feeds over half of the global population. A web-based integrated platform for rice microarray annotation and data analysis in various biological contexts is presented, which provides a convenient query for comprehensive annotation compared with similar databases. Coupled with existing rice microarray data, it provides online analysis methods from the perspective of bioinformatics. This comprehensive bioinformatics analysis platform is composed of five modules, including data retrieval, microarray annotation, sequence analysis, results visualization and data analysis. The BioChip module facilitates the retrieval of microarray data information via identifiers of "Probe Set ID", "Locus ID" and "Analysis Name". The BioAnno module is used to annotate the gene or probe set based on the gene function, the domain information, the KEGG biochemical and regulatory pathways and the potential microRNA which regulates the genes. The BioSeq module lists all of the related sequence information by a microarray probe set. The BioView module provides various visual results for the microarray data. The BioAnaly module is used to analyze the rice microarray's data set.

Automated instrumental method for on-line fraction analysis and peak deconvolution in gradient multicomponent overloaded high performance liquid chromatography

An automated method for deconvolution of overloaded band profiles in gradient elution is described. The instrumental set-up consists of a pseudo-bidimensional HPLC system, where overloaded band profiles generated in the first direction are sampled on the second one. The method, previously employed under isocratic conditions, has been now extended to gradient elution, where one has to face the problem of band compression (and possibly band interference) during gradient, which decreases the time-window available along the first direction for sampling the overloaded profiles. The effect of the gradient steepness on the problem of defining a minimum number of sampling points to reconstruct single component bands from overloaded profiles is investigated. This approach is particularly useful in the framework of using inverse method (IM) to determine adsorption isotherm parameters for preparative gradient elution. In fact, it allows for the gathering of the information necessary to run IM calculations with minimum efford, also in cases where the individual component forming the mixture have different UV spectra.

Particle analysis on concentrated particle suspensions by transmission fluctuation spectrometry with band-pass filters: part 2. Experimental results

Transmission fluctuation spectrometry (TFS), as a new method of online and real-time particle analysis developed in recent years, can measure the particle size distribution and particle concentration simultaneously. In the preceding paper, high concentration effects on the TFS using band-pass filters were investigated by numerical simulation, and empirical expressions to correct the effects were obtained. This paper presents a study on the TFS measurements in which the particle concentration varies in a very wide dynamic range. Finally, reasonable results on both the particle size distribution and particle concentration are obtained by introducing empirical corrections into the inversion algorithm.

Particle analysis on concentrated particle suspensions by transmission fluctuation spectrometry with band-pass filters: part 1. Simulation

Transmission fluctuation spectrometry (TFS), as a new method of online and real-time particle analysis developed in recent years, can measure the particle size distribution and particle concentration simultaneously. In this work, TFS with band-pass filters is studied by numerical simulation in which the particle concentration varies in a large dynamic range. The results of the simulations show that the transmission fluctuation spectrum is related to the particle concentration of the suspension, the pathlength of the light beam within the particle system and the beam-to-particle diameter ratio. Empirical expressions to correct the effects of particle overlapping on the transmission fluctuation spectrum are obtained, which are found to be experimentally validated.

Numerical methods for on-line power system load flow analysis

Newton-Raphson method is the most widely accepted load flow solution algorithm. However LU factorization remains a computationally challenging task to meet the real-time needs of the power system. This paper proposes the application of very fast multifrontal direct linear solvers for solving the linear system sub-problem of power system real-time load flow analysis by utilizing the state-of-the-art algorithms for ordering and preprocessing. Additionally the unsymmetric multifrontal method for LU factorization and highly optimized Intel® Math Kernel Library BLAS has been used. Two state-of-the-art multifrontal algorithms for unsymmetric matrices namely UMFPACK V5.2.0 and sequential MUMPS 4.8.3 (“Multifrontal Massively Parallel Solver”) are customized for the AC power system Newton-Raphson based load flow analysis. The multifrontal solvers are compared against the state-of-the-art sparse Gaussian Elimination based HSL sparse solver MA48. This study evaluates the performance of above multifrontal solvers in terms of number of factors, computational time, number of floating-point operations and memory, in the context of load flow solution on nine systems including very large real power systems. The results of the performance evaluation are reported. The proposed method achieves significant reduction in computational time.

Fluorescence spectroscopy as a novel method for on-line analysis of biocatalytic C–C bond formations

On-line analysis of bioprocesses is of increasing interest avoiding the time delay for off-line sample preparation and the following analyses via chromatographic methods. Moreover, continuous monitoring of the reaction components during chemo- or biocatalytic transformations provides a direct control of the process. Since productivity of the processes can be controlled simultaneously, on-line monitoring of the processes is attractive for industrial applications. The reliable in situ monitoring of biocatalyzed reactions has been a challenge where reactions run in aqueous solutions. Limited work has been published on the use of spectroscopic methods for on-line analysis of biocatalytic reactions up to now. However, in this communication two dimensional (2D)-fluorescence spectroscopy has been proved to be an effective tool for on-line monitoring of the carboligation reactions catalyzed by wild type benzoylformate decarboxylase (BFD) from Pseudomonas putida . BFD is a thiamine diphosphate (ThDP)-dependent enzyme that catalyzes the asymmetric C–C bond formation to ( S )-2-hydroxypropiophenone (( S )-2-HPP) starting from benzaldehyde and acetaldehyde. The analysis of the fluorescence spectra was achieved by chemometric modeling performing principle component analysis (PCA) and partial least square (PLS) regression. The derived chemometric models were used for the validation of concentrations of yielded 2-HPP and the substrate benzaldehyde with low root mean square error of calibration (RMSEC).

Human-error-based design of barriers and analysis of their uses

The paper discusses on the concept of human errors when operators use barriers or when barriers have to be designed to decrease risks associated with human behaviours. It gives taxonomies of barriers and of their uses and develops the concept of the human-error-based design of barriers to control human errors. Human error assessment methods are then proposed regarding three dimensions: retrospective analysis methods, prospective analysis methods and on-line analysis methods. A new methodology including these dimensions is proposed to take into account several uses of barriers: normal uses, unintentional erroneous uses, intentional diverted uses and uses of new barriers. In order to achieve the identification of these barrier uses, this approach is based on the comparison between the prescriptive and predictive behaviours for a prospective analysis or between prescriptive and real behaviours for a retrospective analysis to define new barriers or to redesign the existing ones. A management of the learning process of such barrier uses is integrated in order to make this design or redesign processes possible.

Quantitative Online Analysis of Liquid-Phase Products of Methanol Oxidation in Aqueous Sulfuric Acid Solutions Using Electrospray Ionization Mass Spectrometry

We describe a novel method and setup for quantitative online analysis of the liquid-phase methanol oxidation products in acidic aqueous solutions by electrospray ionization mass spectrometry (ESI-MS). This includes a specially designed flow system, which allows continuous online mixing, derivatization, extraction, separation, and quantitative detection within ca. 3 min. For electrospray ionization of formaldehyde, it is first online-derivatized by 2,4-dinitrophenyl hydrazine to form the easily ionizable 2,4-dinitrophenyl hydrazone. Then, both formic acid and derivatized formaldehyde are online extracted into an immiscible organic phase, which, after separation from the aqueous phase, is piped to the ESI-MS for analysis. This strategy ensures complete removal of the highly corrosive sulfuric acid from the analyte and allows the liquid-phase methanol oxidation reaction (MOR) products (formaldehyde and formic acid) to be quantitatively detected by ESI-MS. Finally, the potential of this method for online analysis in electroanalysis and electrocatalysis is discussed.

Painting problem solver: Determining which paint spray application method produces a drier coating

The Co-Al bimetallic hydroxide nanocomposites were synthesized and used as in-tube solid-phase microextraction coating. The nanocomposites-coated fibers were packed in a PEEK tube and tested for the extraction of eight polycyclic aromatic hydrocarbons (PAHs) coupled with high performance liquid chromatography. Several parameters affecting the PAHs extraction including the sampling volume, sampling flow rate, methanol content and desorption time were investigated. Under the optimized conditions, the extraction tube with nanocomposites coating exhibited remarkable extraction performance towards PAH targets. An online analysis method was achieved with the limits of detection less than 0.02 μg L−1 and the linearity in the range from 0.03 to 15 μg L−1. The recoveries of the method for two water samples with spiking levels of 1 and 10 μg L−1 ranged from 83 to 121%. Extraction repeatability and preparation repeatability were less than 4.0% and 10.9%, respectively.

Development of an on-line isotope dilution laser ablation inductively coupled plasma mass spectrometry (LA–ICP-MS) method for determination of boron in silicon wafers

A method has been developed based on an on-line isotope dilution technique couple with laser ablation/inductively coupled plasma mass spectrometry (LA–ICP-MS), for the determination of boron in p-type silicon wafers. The laser-ablated sample aerosol was mixed on-line with an enriched boron aerosol supplied continuously using a conventional nebulization system. Upon mixing the two aerosol streams, the isotope ratio of boron changed rapidly and was then recorded by the ICP-MS system for subsequent quantification based on the isotope dilution principle. As an on-line solid analysis method, this system accurately quantifies boron concentrations in silicon wafers without the need for an internal or external solid reference standard material. Using this on-line isotope dilution technique, the limit of detection for boron in silicon wafers is 2.8 × 10 15 atoms cm −3. The analytical results obtained using this on-line methodology agree well with those obtained using wet chemical digestion methods for the analysis of p-type silicon wafers containing boron concentrations ranging from 1.0 × 10 16 to 9.6 × 10 18 atoms cm −3.

Fully automated deconvolution method for on-line analysis of time-resolved fluorescence spectroscopy data based on an iterative Laguerre expansion technique

Time-resolved fluorescence spectroscopy (TRFS) is a powerful analytical tool for quantifying the biochemical composition of organic and inorganic materials. The potential of TRFS for tissue diagnosis has been recently demonstrated. To facilitate the translation of TRFS to the clinical arena, algorithms for online TRFS data analysis are essential. A fast model-free TRFS deconvolution algorithm based on the Laguerre expansion method has previously been introduced. One limitation of this method, however, is the need to heuristically select two parameters that are crucial for the accurate estimation of the fluorescence decay: the Laguerre parameter alpha and the expansion order. Here, a new implementation of the Laguerre deconvolution method is introduced, in which a nonlinear least-square optimization of the Laguerre parameter alpha is performed, and the optimal expansion order is selected based on a minimum description length criterion (MDL). In addition, estimation of the zero-time delay between the recorded instrument response and fluorescence decay is also performed based on normalized mean square error criterion (NMSE). The method is validated on experimental data from fluorescence lifetime standards, endogenous tissue fluorophores, and human tissue. The proposed automated Laguerre deconvolution method will facilitate online applications of TRFS, such as real-time clinical tissue diagnosis.

GABAergic hub neurons orchestrate synchrony in developing hippocampal networks

Event Abstract Back to Event GABAergic hub neurons orchestrate synchrony in developing hippocampal networks Rosa Cossart1* 1 INMED-INSERM, France Network theory predicts that scale-free power law distributed topologies, which include “hubs” i.e. super-connected nodes, are an effective design regarding synchronization. Although the non-random structure of cortical networks has been largely described, the existence of functional hubs in living brain networks lacked experimental evidence. We have recently developed a method for online analysis of network dynamics based on two-photon imaging that enables to localize during an experiment, neurons driving population activity without any a priori assumption. Using network dynamics imaging, online reconstruction of functional connectivity and targeted intracellular recordings, we observed that developing hippocampal networks follow a scale-free topology and performed recordings from functional hubs. Morphometric analysis revealed that recorded hippocampal hubs driving early network synchronizations are a fraction of GABAergic interneurons displaying remarkably widespread axonal projections. In other words, we found superconnected neurons (circuit-hubs) orchestrating network synchrony in developing hippocampal slices. I will explain how we found them and describe their specific morpho-physiological properties as well as show how they control network dynamics. Conference: INMED Satellite Conference of SFN - Neuroscience 2009, Multiple Facets of GABA in Brain Development, Chicago, United States, 16 Oct - 16 Oct, 2009. Presentation Type: Oral Presentation Topic: Abstracts Citation: Cossart R (2009). GABAergic hub neurons orchestrate synchrony in developing hippocampal networks. Conference Abstract: INMED Satellite Conference of SFN - Neuroscience 2009, Multiple Facets of GABA in Brain Development. doi: 10.3389/conf.neuro.03.2009.13.011 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 23 Jul 2009; Published Online: 23 Jul 2009. * Correspondence: Rosa Cossart, INMED-INSERM, 13331 Marseille, France, cossart@inmed.univ-mrs.fr Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Rosa Cossart Google Rosa Cossart Google Scholar Rosa Cossart PubMed Rosa Cossart Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Sampling and preconcentration techniques for determination of volatile organic compounds in air samples

Because air is complex and heterogeneous, continuously evolving in time and space and being influenced by atmospheric and geographical conditions, sampling is crucial in air analysis. Moreover, due to the low levels of pollutants present in the atmosphere, enrichment is often required. This review deals with the most common techniques for sampling and preconcentration of volatile organic compounds (VOCs) in air samples (e.g., whole-air collection in containers, which is usually combined with preconcentration step, and solid-sorbent enrichment methods). We also describe solid sorbents used to trap VOCs in air, and subsequent desorption techniques. In recent years, there have been many efforts to improve on-line analysis methods, which offer real-time data and are useful in providing rapid results. We examine the application of sorbent trapping to on-line analysis and other techniques for on-line analysis (e.g., membrane extraction and selected-ion-flow-tube mass spectrometry).

Control problems in contingency during flight of a space vehicle with low thrust engine

An approximate method of online analysis of contingency during the flight of a space vehicle with low thrust engine and nuclear power unit to asteroids is proposed. The properties of dependence of the vehicle mass near the target on the flight characteristics and parameters of the space vehicle are used. Examples of the choice of a new variant of the expedition to several asteroids of the Main belt in the case of a contingent change in the power of the energy unit are given.

A New Integrated Fault Diagnosis And Analysis System For Large-Scale Power Grid

This paper describes an efficient methodology that can be used in an integrated fault diagnosis and analysis system (IFDAS) for large-scale power grid. The IFDAS extended from some software tools used in contemporary power grid consists of four main parts: fault information processing, fault diagnosis, power gird vulnerability analysis and prediction contingency analysis. It also has some innovative characteristics. First, the large-scale power system IFDAS in this paper is based on slow successive tripping procedure of cascading failure. Second, the concept of coordination is brought into the cascading failure analysis and defence scheme of IFDAS. Third, it is an on-line cascading failure analysis method which can trace real-time operation conditions. And last it makes full use of data acquisition channels and monitor system dynamic behavior. According to the slow successive tripping procedure character of the cascading failure and blackouts, the concept of a large-scale power system IFDAS is presented. And the features, structure, flow and responding mechanism of the IFDAS are all detailed discussed. Finally, case analysis shows that the IFDAS is a system good at fast identifying cause during cascading failure, supplying optimum dispatching strategy, and avoiding blackouts effectively.

Measurements of enhanced electron screening in d+d reactions under UHV conditions

Observation of the enhanced electron screening in metallic environments is of fundamental importance for the understanding of strongly coupled astrophysical plasmas. Experimental screening energies determined by different groups for many metals are much larger than the theoretical predictions. However, a comparison between experimental and theoretical data is rather ambiguous because of the contributions of systematic errors in the experiments. One of the most important problems is the uncertainty resulting from the oxidation of the target surface during the measurements. Here, we present results of the first ultra-high vacuum (UHV) experiments studying d+d nuclear reactions in a deuterized Zr target for which the experimental discrepancies are especially large. The total cross sections and angular distributions of the 2H(d,p)3H and 2H(d,n)3He reactions have been measured using a deuteron beam of energies between 8 and 30 keV provided by an electron cyclotron resonance ion source with excellent long-term stability. The cleanness of the target surface has been assured by combining Ar sputtering of the target and Auger spectroscopy. In an on-line analysis method, the homogeneity of the implanted deuteron densities could be monitored also. The resulting screening energy for Zr confirms the large value obtained in a previous experiment under poorer vacuum conditions.

An automated on-line method for simultaneous analysis of phenothiazines in human serum by high-performance liquid chromatography/sonic spray ionization mass spectrometry using backflush column switching

An automated on-line method for simultaneous analysis of five phenothiazine drugs by high-performance liquid chromatography (HPLC)/sonic spray ionization mass spectrometry (SSI-MS) has been established, using backflush column switching. A 400-μl portion of serum sample diluted 81-fold with distilled water was subjected to the on-line system. In the system, an Oasis HLB cartridge was used as the precolumn for extraction; large molecules such as proteins in serum were discarded by use of distilled water containing 0.1% formic acid as a mobile phase. After switching a valve, the analytes trapped in the precolumn were eluted in the backflush mode and separated by a Chromolith Performance RP-18e column, which is composed of C18-bonded monolithic silica. The column effluents were then introduced into the SSI-MS. The present method provided successful separation and determination of six phenothiazines including an internal standard. Satisfactory linearities, reproducibility, and sensitivity were obtained at concentration levels that matched the toxic levels of phenothiazines. All drug peaks appeared within 18 min, and the system could be reequilibrated in only about 8 min for the next run. Because of the simplicity and rapidness of the method, it is likely to be useful in the fields of emergency medicine and forensic toxicology.