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Determination of gold in gold jewellery alloys by ICP spectrometry
M. Brill,K. -H. Wiedemann
Gold Bulletin , 1992, DOI: 10.1007/BF03214719
Abstract: As a result of recent research and development work supported by World Gold Council, Inductively Coupled Plasma Spectrometry (ICP) is rapidly emerging as a serious and viable alternative to the centuries-old cupellation or fire assay method for the determination of gold in gold jewellery alloys.
Applications of X-ray Fluorescence Spectrometry in Elemental Analysis of Crystals
X射线荧光光谱在晶体材料组成分析中的应用

ZHUO Shang-Jun,TAG Guang-Yi,JI Ang,SHENG Cheng,SHEN Ru-Xiang,
卓尚军
,陶光仪,吉昂,盛成,申如香

无机材料学报 , 2003,
Abstract: The applications of X-ray fluorescence spectrometry in elemental analysis of crystals were reviewed. Although it is an effective and efficient approach for elemental analysis, X-ray fluorescence analyses require different sample preparation methods depending on different sample types and require calibration standards to correct matrix effects. Abnormal reflection may lead to complicated background and confused qualitative interpretation or/and quantitative measuring conditions if the measured specimen is a single crystal. In this case, the fusion method is preferable. Attention must be paid to the uncertainty of the measurement when the results are employed to a specific purpose.
THE QUANTITATIVE EDS ANALYSIS OF THE CONSTITUENTS OF BINARY ALLOYS WITHOUT STANDARD SAMPLES
二元合金成份的无标样X光能谱定量分析

WU ZI-QIN,GAO QIAO-JUN,GE SEN-LIN,
吴自勤
,高巧君,葛森林

物理学报 , 1980,
Abstract: In general, the quantitative electron probe microanalysis is based on comparisons with standard samples. In this article, a method of the quantitative analysis of binary alloys without reference to standard samples is introduced. After simultaneous measurements of the ratios of the Ka photons of two elements in the binary alloys (Cu-Ga, GaAs) in SEM-EDS equipment, the constituents of the binary alloys are calculated from a simplified formula for the energy loss of the incident electrons, the X-ray excitation cross-section and the secondary fluorescence. When the overvol-tage of the incident electrons is kept in the range 2-3, the calculated results show good agreement with the actual constituents. The "instrument sensitivity" of the characteristic X-ray of the pure elements determined in the literature is calculated and discussed by using this simplified model.
Current Status and Advances in Quantitative Proteomic Mass Spectrometry  [PDF]
Valerie C. Wasinger,Ming Zeng,Yunki Yau
International Journal of Proteomics , 2013, DOI: 10.1155/2013/180605
Abstract: The accurate quantitation of proteins and peptides in complex biological systems is one of the most challenging areas of proteomics. Mass spectrometry-based approaches have forged significant in-roads allowing accurate and sensitive quantitation and the ability to multiplex vastly complex samples through the application of robust bioinformatic tools. These relative and absolute quantitative measures using label-free, tags, or stable isotope labelling have their own strengths and limitations. The continuous development of these methods is vital for increasing reproducibility in the rapidly expanding application of quantitative proteomics in biomarker discovery and validation. This paper provides a critical overview of the primary mass spectrometry-based quantitative approaches and the current status of quantitative proteomics in biomedical research. 1. Introduction Quantification in a proteomics setting relies on the ability to detect small changes in protein and peptide abundance in response to an altered state [1]. Differential analysis is generated from LC-MS experiments and can be carried out using both label and label-free approaches. For trace amounts of proteins within complex proteomes such as plasma, tears, and urine, no singular technique should be used as a stand-alone guarantee of quantitative precision without hypothesis-driven, targeted approaches. Enrichment and fractionation of specific classes of protein is beneficial during the discovery phase of a project, but because these methods can involve numerous steps, they can become a limiting factor for large scale validation. The variability introduced by multiple methods prior to quantitative mass spectrometry should be assessed, and it is paramount that protein measurements reflect the authentic concentration in the original sample. The development of methods for accurate protein quantitation is one of the most challenging areas of proteomics. Quantitative proteomics comes in two forms: absolute and relative. Relative quantitation compares the levels of a specific protein in different samples with results being expressed as a relative fold change of protein abundance [2]. Absolute quantitation is the determination of the exact amount or mass concentration of a protein, for example, in units of ng/mL of a plasma biomarker. Traditional proteomic quantitation approaches rely on high-resolution protein separation by 2D gels. The use of dyes, fluorophores, or radioactivity to label proteins allows visualization of spots/bands with differential intensities [3, 4]. These methods facilitate
Mass Spectrometry-Based Label-Free Quantitative Proteomics
Wenhong Zhu,Jeffrey W. Smith,Chun-Ming Huang
Journal of Biomedicine and Biotechnology , 2010, DOI: 10.1155/2010/840518
Abstract: In order to study the differential protein expression in complex biological samples, strategies for rapid, highly reproducible and accurate quantification are necessary. Isotope labeling and fluorescent labeling techniques have been widely used in quantitative proteomics research. However, researchers are increasingly turning to label-free shotgun proteomics techniques for faster, cleaner, and simpler results. Mass spectrometry-based label-free quantitative proteomics falls into two general categories. In the first are the measurements of changes in chromatographic ion intensity such as peptide peak areas or peak heights. The second is based on the spectral counting of identified proteins. In this paper, we will discuss the technologies of these label-free quantitative methods, statistics, available computational software, and their applications in complex proteomics studies.
Analysis of Substrate Specificity and Kinetics of Cyclic Nucleotide Phosphodiesterases with N’-Methylanthraniloyl-Substituted Purine and Pyrimidine 3′,5′-Cyclic Nucleotides by Fluorescence Spectrometry  [PDF]
Daniel Reinecke, Frank Schwede, Hans-Gottfried Genieser, Roland Seifert
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0054158
Abstract: As second messengers, the cyclic purine nucleotides adenosine 3′,5′-cyclic monophosphate (cAMP) and guanosine 3′,5′-cyclic monophosphate (cGMP) play an essential role in intracellular signaling. Recent data suggest that the cyclic pyrimidine nucleotides cytidine 3′,5′-cyclic monophosphate (cCMP) and uridine 3′,5′-cyclic monophosphate (cUMP) also act as second messengers. Hydrolysis by phosphodiesterases (PDEs) is the most important degradation mechanism for cAMP and cGMP. Elimination of cUMP and cCMP is not completely understood, though. We have shown that human PDEs hydrolyze not only cAMP and cGMP but also cyclic pyrimidine nucleotides, indicating that these enzymes may be important for termination of cCMP- and cUMP effects as well. However, these findings were acquired using a rather expensive HPLC/mass spectrometry assay, the technical requirements of which are available only to few laboratories. N’-Methylanthraniloyl-(MANT-)labeled nucleotides are endogenously fluorescent and suitable tools to study diverse protein/nucleotide interactions. In the present study, we report the synthesis of new MANT-substituted cyclic purine- and pyrimidine nucleotides that are appropriate to analyze substrate specificity and kinetics of PDEs with more moderate technical requirements. MANT-labeled nucleoside 3′,5′-cyclic monophosphates (MANT-cNMPs) are shown to be substrates of various human PDEs and to undergo a significant change in fluorescence upon cleavage, thus allowing direct, quantitative and continuous determination of hydrolysis via fluorescence detection. As substrates of several PDEs, MANT-cNMPs show similar kinetics to native nucleotides, with some exceptions. Finally, they are shown to be also appropriate tools for PDE inhibitor studies.
Tools for the Quantitative Analysis of Sedimentation Boundaries Detected by Fluorescence Optical Analytical Ultracentrifugation  [PDF]
Huaying Zhao, Ernesto Casillas, Hari Shroff, George H. Patterson, Peter Schuck
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0077245
Abstract: Fluorescence optical detection in sedimentation velocity analytical ultracentrifugation allows the study of macromolecules at nanomolar concentrations and below. This has significant promise, for example, for the study of systems of high-affinity protein interactions. Here we describe adaptations of the direct boundary modeling analysis approach implemented in the software SEDFIT that were developed to accommodate unique characteristics of the confocal fluorescence detection system. These include spatial gradients of signal intensity due to scanner movements out of the plane of rotation, temporal intensity drifts due to instability of the laser and fluorophores, and masking of the finite excitation and detection cone by the sample holder. In an extensive series of experiments with enhanced green fluorescent protein ranging from low nanomolar to low micromolar concentrations, we show that the experimental data provide sufficient information to determine the parameters required for first-order approximation of the impact of these effects on the recorded data. Systematic deviations of fluorescence optical sedimentation velocity data analyzed using conventional sedimentation models developed for absorbance and interference optics are largely removed after these adaptations, resulting in excellent fits that highlight the high precision of fluorescence sedimentation velocity data, thus allowing a more detailed quantitative interpretation of the signal boundaries that is otherwise not possible for this system.
Quantitative Fluorescence Excitation Spectra for Synthetic Eumelanin  [PDF]
Stephen Nighswander-Rempel,Jennifer Riesz,Joel Gilmore,Jacques Bothma,Paul Meredith
Physics , 2005,
Abstract: Previously reported excitation spectra for eumelanin are sparse and inconsistent. Moreover, these studies have failed to account for probe beam attenuation and emission reabsorption within the samples, making them qualitative at best. We report for the first time quantitative excitation spectra for synthetic eumelanin, acquired for a range of solution concentrations and emission wavelengths. Our data indicate that probe beam attenuation and emission reabsorption significantly affect the spectra even in low-concentration eumelanin solutions and that previously published data do not reflect the true excitation profile. We apply a correction procedure (previously applied to emission spectra) to account for these effects. Application of this procedure reconstructs the expected relationship of signal intensity with concentration, and the normalised spectra show a similarity in form to the absorption profiles. These spectra reveal valuable information regarding the photophysics and photochemistry of eumelanin. Most notably, an excitation peak at 365 nm (3.40 eV), whose position is independent of emission wavelength, is possibly attributable to a DHICA component singly linked to a polymeric structure.
Variance function estimation in quantitative mass spectrometry with application to iTRAQ labeling  [PDF]
Micha Mandel,Manor Askenazi,Yi Zhang,Jarrod A. Marto
Statistics , 2013, DOI: 10.1214/12-AOAS572
Abstract: This paper describes and compares two methods for estimating the variance function associated with iTRAQ (isobaric tag for relative and absolute quantitation) isotopic labeling in quantitative mass spectrometry based proteomics. Measurements generated by the mass spectrometer are proportional to the concentration of peptides present in the biological sample. However, the iTRAQ reporter signals are subject to errors that depend on the peptide amounts. The variance function of the errors is therefore an essential parameter for evaluating the results, but estimating it is complicated, as the number of nuisance parameters increases with sample size while the number of replicates for each peptide remains small. Two experiments that were conducted with the sole goal of estimating the variance function and its stability over time are analyzed, and the resulting estimated variance function is used to analyze an experiment targeting aberrant signaling cascades in cells harboring distinct oncogenic mutations. Methods for constructing conservative $p$-values and confidence intervals are discussed.
Quantitative Model of Large Magnetostrain Effect in Ferromagnetic Shape Memory Alloys  [PDF]
A. A. Likhachev,K. Ullakko
Physics , 1999, DOI: 10.1007/s100510050128
Abstract: A quantitative model describing large magnetostrain effect observed in several ferromagnetic shape memory alloys such as Ni2MnGa is briefly reported.The paper contains an exact thermodynamic consideration of the mechanical and magnetic properties for a similar type materials. As a result, the basic mechanical state equation including magnetic field effect is directly derived from a general Poisson's rule. It is shown that the magnetic field induced deformation effect is directly connected with the strain dependence of magnetization. A simple model of magnetization and its dependence on the strain is considered and applied to explain the results of experimental study of large magnetostrain effects in Ni2MnGa.
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