Identification and quantification of sources of variation in the analysis of steel

In steel industries a need exists for the reduction of variation in the element concentrations. This need is triggered by an increasing demand for high quality steel products by clients. The results of a large-scale experiment concerning the identification and quantification of sources of variation in the production, sampling and analysis of steel are presented. The results are obtained by means of a strategic approach that consists of six steps. By means of this strategic approach, insight is obtained in the build-up of the total variation. This knowledge can be used to reduce the influence of those factors that have a major impact on the total variation. Attention is focused on estimating the magnitude of sources of variation apparent in sampling of certain stages of the steel making process and in analysis of steel samples by means of spark emission spectrometry.     

Identification and quantification of sources of variation in the analysis of steel

In steel industries a need exists for the reduction of variation in the element concentrations. This need is triggered by an increasing demand for high quality steel products by clients. The results of a large-scale experiment concerning the identification and quantification of sources of variation in the production, sampling and analysis of steel are presented. The results are obtained by means of a strategic approach that consists of six steps. By means of this strategic approach, insight is obtained in the build-up of the total variation. This knowledge can be used to reduce the influence of those factors that have a major impact on the total variation. Attention is focused on estimating the magnitude of sources of variation apparent in sampling of certain stages of the steel making process and in analysis of steel samples by means of spark emission spectrometry. Received: 6 November 1999 / Revised: 10 February 2000 / Accepted: 19 March 2000     

Empirical kernel map approach to nonlinear underdetermined blind separation of sparse nonnegative dependent sources: pure component extraction from nonlinear mixture mass spectra

Nonlinear underdetermined blind separation of nonnegative dependent sources consists in decomposing a set of observed nonlinearly mixed signals into a greater number of original nonnegative and dependent component (source) signals. This hard problem is practically relevant for contemporary metabolic profiling of biological samples, where sources (a.k.a. pure components or analytes) are aimed to be extracted from mass spectra of nonlinear multicomponent mixtures. This paper presents a method for nonlinear underdetermined blind separation of nonnegative dependent sources that comply with a sparse probabilistic model, that is, sources are constrained to be sparse in support and amplitude. This model is validated on experimental pure component mass spectra. Under a sparse prior, a nonlinear problem is converted into an equivalent linear one comprised of original sources and their higher‐order, mostly second‐order, monomials. The influence of these monomials, which stand for error terms, is reduced by preprocessing a matrix of mixtures by means of robust principal component analysis and hard, soft and trimmed thresholding. Preprocessed data matrices are mapped in high‐dimensional reproducible kernel Hilbert space (RKHS) of functions by means of an empirical kernel map. Sparseness‐constrained nonnegative matrix factorizations in RKHS yield sets of separated components. They are assigned to pure components from the library using a maximal correlation criterion. The methodology is exemplified on demanding numerical and experimental examples related respectively to extraction of eight dependent components from three nonlinear mixtures and to extraction of 25 dependent analytes from nine nonlinear mixture mass spectra recorded in nonlinear chemical reaction of peptide synthesis. Copyright © 2014 John Wiley & Sons, Ltd.     

Calibrant delivery for mass spectrometry

This article describes a means of sampling ions that are created at a location remote from the primary ion source used for mass spectral analysis. Such a source can be used for delivery of calibrant ions on demand. Calibrant ions are sprayed into an atmospheric pressure chamber, at a position substantially removed from the sampling inlet. A gas flow sweeps the calibrants towards the sampling inlet, and a new means for toggling the second ion beam into the instrument can be achieved with the use of a repelling field established by an electrode in front of the sampling inlet. The physical separation of two or more sources of ions eliminates detrimental interactions due to gas flows or fields. When using a nanoflow electrospray tip as the primary ion source, the potential applied to the tip completely repels calibrant ions and there is no compromise in terms of electrospray performance. When calibrant ions are desired, the potential applied to the nanoflow electrospray tip is lowered for a short period of time to allow calibrant ions to be sampled into the instrument, thus providing a means for external calibration that avoids the typical complications and compromises associated with dual spray sources. It is also possible to simultaneously sample ions from multiple ion beams if necessary for internal mass calibration purposes. This method of transporting additional ion beams to a sampling inlet can also be used with different types of atmospheric pressure sources such as AP MALDI, as well as sources configured to deliver ions of different polarity.     

The energy sprad of some radiation fields used in activation analysis

The global results of the activation process are genrally dependent of the activated material, type of nuclear reaction, energy of incident particles, etc. by means of some specific parameters (crouss section, flux denisty, etc.). To characterize the above mentioned process, the energy behavior study of the radiation fiels generated by extended sources can be useful. In this paper, the energy spread in nondispersive media of some exoergic nuclear reactions (i.e., d-D, d-T reactions at low energy excitation, levels, etc.) lodged in axi-symmetrically emitting disk-shaped sources, used as radiation sources in activation anlysis, have been investigated analytically. The contribution of the first tems of an angular depending series approximation is underlined. Computationally tractable expressions, in tems of elementary and elliptic integral type functions, are proposed.     

Application of instrumental neutron activation analysis to study ceramic fragments from Damascus Castle site,Syria

Summary Thirty-three archaeological ceramic fragment samples from Damascus Castle archaeological site, Damascus city, Syria, were analyzed using instrumental neutron activation analysis (INAA). 36 elements were determined. These elemental concentrations have been processed using two multivariate statistical methods, cluster and factor analysis in order to determine similarities and correlation between the various samples. Factor analysis confirms that 84.8% of the ceramics samples classified by cluster analysis are correctly classified by cluster analysis. The results provided persuasive evidence that Castle pottery used at least four different clay sources. Moreover, by means of systematic local analysis it will be clear whether these sources are local or not.     

Toward on-chip X-ray analysis

The possibility of performing chemical analysis and structure determinations with the use of X-rays in a microfluidic chip environment is explored. Externally generated radiation, radioisotope irradiation and on-chip generated X-rays were considered as excitation means for the performance of sample analysis with the techniques of X-ray fluorescence and diffraction. The absorption properties of chip-building materials by different radiation sources are reviewed and data on absorption coefficients calculated, upon which recommendations for optimisations with the use of various X-ray sources may be made. The capabilities and limitations of on-chip X-ray analysis are placed in perspective by preliminary experimental results of diffraction, fluorescence and on-chip X-ray generation experiments.     

Determination of equilibrium parameters by minimization of an extended sum of squares

A method is proposed for the evaluation of equilibrium parameters from potentiometric data, in which all the sources of random error are taken into account. This means including in the minimized sum the residuals in all the quantities subject to error (titrant volume, emf, parameters of composition of the titrant and titrand, parameters of electrode characteristics, and equilibrium constants known from other experiments). The method of preparation of the solutions is represented by a directed, acyclic graph which allows consideration of the sources of error connected with the composition of the solutions, and avoidance of inconsistency in the composition characteristics. Numerical examples are presented.     

Capabilities of superpure actinide and stable isotope product in Russian Federal Nuclear Center

The paper describes the production of highly enriched isotopes of uranium, plutonium and curium by means of electromagnetic separation for scientific and applied research in physics, chemistry, geology and other field. The equipment and radiochemical methods used allows to provide the isotopic pure samples in quantities sufficient to set up nuclear physics experiments, to produce reference materials and standard sources for calibration of radiometrical and mass spectrometrical equipment and for use in radionuclear metrology. Methods of fabrication of special sources or targets and layers of highly enriched isotopes on various substrated are presented. The brief information on developing stable isotope production program is also presented.     

Background,fundamental understanding and progress in electrochemical capacitors

Journal of Solid State Electrochemistry - Supercapacitors means electrochemical capacitors are being considered these days to be a good alternative for the conventional power sources (fuel cells...     

Investigation of various SiC materials by means of EPMA/WDS techniques

The microstructure and compositions of SiC materials from different sources and processing routes were investigated by means of EPMA/WDS and image analysis techniques. The influence of various sources of errors like carbon contamination and spectrometers defocusing on the analysis has been assessed.The presence of dissolved sintering aids, or impurities, and their distributions were investigated by EPMA/WDS. In addition, inhomogeneities, porosity agglomerations and heterogeneous inclusions were found in almost all the SiC materials, which are known to influence the corrosion and mechanical behavior of the material.Quantification of secondary phase contents was performed by means of image analysis, EPMA and, when possible, by density measurement. All methods are affected by errors of difficult assessment. In particular, the EPMA/WDS technique has to handle the problem of non homogeneous volumes of analysis. Two quantitative approaches were attempted, both based on the averaging of many points. In the first, the beam was highly focused. In the second approach, large areas (from 10 to 50 m in diameter) were illuminated. The errors and limits of these methods are discussed and the results compared.     

Optimization of Fermentation Medium for Epothilones Production with Sequential Statistical Approach

A sequential statistical approach was applied to optimizing the fermentation medium of epothilones(Epos) production by means of a mutant which was obtained by treating polyangium cellulosum ATCC 15384 with nitrite and ultraviolet. The effects of different carbon sources and nitrogen sources on the fermentation medium were tested, and the suitable ones were selected. Then a uniform design was employed to design the experiments. A linear model was developed for identifying the significant components in fermen...     

Surface-assisted reduction of aniline oligomers, N-phenyl-1,4-phenylenediimine and thionin in atmospheric pressure chemical ionization and atmospheric pressure photoionization

Reduction of the oligomers formed from on-line electropolymerization of aniline, the compound N-phenyl-1,4-phenylenediimine, and the thiazine dye thionin was observed in both an atmospheric pressure chemical ionization and an atmospheric pressure photoionization source. The reduction, which alters the mass of these analytes by 2 Da, was shown to occur by means of a surface-assisted process which involves reactive species, possibly hydrogen radicals, generated from protic solvents in the ionization plasma. Reduction was minimized by limiting protic solvents, by using a high heated nebulizer temperature, and by using a clean, heated nebulizer probe liner. The expected generality of this reduction process, and the possibility of similar reduction processes in other plasma ionization sources are discussed in relation to the use of these ion sources for on-line electrochemistry/mass spectrometry experiments.     

Multivariate geostatistical analysis of soil contaminations

Soil is one of the most endangered compartments of our environment. The input of pollutants into the soil caused by industrial production, agriculture, and other human activities is a problem of high relevance. A contour analysis of soil contamination is the first step to characterize the size and magnitude of pollution and to detect emission sources of heavy metals. The evaluation and assessment of the large number of measured samples and pollutants require the use of efficient statistical methods which are able to discover both spatial and multivariate relationships. The evaluation of the presented case study – soil contamination by heavy metals – is carried out by means of multivariate geostatistical methods, also described as theory of linear coregionalization. Multivariate geostatistics connects the advantages of common geostatistical methods (spatial correlation) and multivariate data analysis (multivariate relationships). In the given case study of soil pollution by heavy metal emissions it is excellently possible to detect multivariate spatial correlations between different heavy metals in the soil and to determine their common emission sources. These emission sources are located in the area under investigation. Received: 2 October 1997 / Revised: 22 January 1998 / Accepted: 27 January 1998     

乙二胺四乙酸辅助水热法合成NaYF_4纳米晶

用络合剂乙二胺四乙酸(EDTA)辅助水热法合成了NaYF4纳米球和微米棱柱,通过控制反应条件得到了立方相和六方相纳米晶体;采用X射线粉末衍射仪(XRD)、扫描电子显微镜(SEM)及荧光光谱仪(PL)分析了产物的结构、形貌及发光性能.结果表明,络合剂EDTA和氟化物的物质的量对NaYF4的形貌和粒度有很大影响,且产物的荧光性能呈现出尺寸依赖性.     

Low pressure plasma spectroscopy – Spectrochemical analysis,technology process investigation and fundamental spectroscopic data

Low pressure plasma, its characteristics, excitation sources and applications are shortly presented. The paper is focused on three areas of low pressure plasma spectroscopy, i.e. spectrochemical analysis, investigation of technology processes and fundamental reference data. Matrix effects occurring in spectrochemical analyses by means of hollow cathode discharges are presented. Investigation and monitoring of processes of production of new materials in glow discharges are shown. Applicability of low pressure plasma for the determination of atomic (transition probabilities) and molecular reference data (electronic, vibrational and rotational constants) and utilization of molecular data are discussed.     

Comparison of figures of merit for fluorimetric analysis of rhodamine complexes of gallium and indium by excitation with pulsed laser and by xenon arc sources

Optimum conditions have been established for formation and extraction of indium-Rhodamine complexes, and limits of detection found for fluorimetric determination of gallium and indium by means of Rhodamine dyes, using the excitation with pulsed laser and xenon arc sources.     

First synthesis of the chiral mixed O/S ligands, 1,2-sulfinyl thiols: application as chiral proton sources in enantioselective protonations of enolates

A suitable method for the preparation of the chiral mixed O/S ligands 1,2-sulfinyl thiols is described. These compounds have then been used as a chiral proton source in the enantioselective protonation of 2-methyl tetralone enolate and the results are compared with those obtained from the analogous alcohols. A theoretical model is proposed to explain the different behaviors exhibited in the protonation reaction for each of these proton sources. Configurational assignments for the new chiral thiols have been carried out by means of X-ray analysis.     

Solid-state structural properties of 2,4,6-trimethoxybenzene derivatives, determined directly from powder X-ray diffraction data in conjunction with other techniques

Structural properties of 2,4,6-trimethoxybenzaldehyde, 2,4,6-trimethoxybenzyl alcohol and 2,4,6-trimethoxyacetophenone have been determined directly from powder X-ray diffraction data, using the direct-space Genetic Algorithm (GA) technique for structure solution followed by Rietveld refinement. Structural similarities and contrasts within this family of materials are elucidated. The work illustrates the value of utilizing information from other sources, including spectroscopic data and computational techniques, as a means of augmenting the structural knowledge established from the powder X-ray diffraction data.