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Статті в журналах з теми "Separation techniques for silicate matrices"
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Bonnand, P., C. Israel, M. Boyet, R. Doucelance, and D. Auclair. "Radiogenic and stable Ce isotope measurements by thermal ionisation mass spectrometry." Journal of Analytical Atomic Spectrometry 34, no. 3 (2019): 504–16. http://dx.doi.org/10.1039/c8ja00362a.
Повний текст джерелаАнотація:
Techniques for the separation of Cerium (Ce) from silicate matrices and for the analysis of radiogenic (ε138Ce) and mass dependent (δ142Ce) Ce isotope variations by Thermal Ionisation Mass Spectrometry (TIMS) are presented in this study.
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Muzi, Elisa, Maxime Cavillon, Matthieu Lancry, François Brisset, Ruyue Que, Diego Pugliese, Davide Janner, and Bertrand Poumellec. "Towards a Rationalization of Ultrafast Laser-Induced Crystallization in Lithium Niobium Borosilicate Glasses: The Key Role of the Scanning Speed." Crystals 11, no. 3 (March 15, 2021): 290. http://dx.doi.org/10.3390/cryst11030290.
Повний текст джерелаАнотація:
Femtosecond (fs)-laser direct writing is a powerful technique to enable a large variety of integrated photonic functions in glass materials. One possible way to achieve functionalization is through highly localized and controlled crystallization inside the glass volume, for example by precipitating nanocrystals with second-order susceptibility (frequency converters, optical modulators), and/or with larger refractive indices with respect to their glass matrices (graded index or diffractive lenses, waveguides, gratings). In this paper, this is achieved through fs-laser-induced crystallization of LiNbO3 nonlinear crystals inside two different glass matrices: a silicate (mol%: 33Li2O-33Nb2O5-34SiO2, labeled as LNS) and a borosilicate (mol%: 33Li2O-33Nb2O5-13SiO2-21B2O3, labeled as LNSB). More specifically, we investigate the effect of laser scanning speed on the crystallization kinetics, as it is a valuable parameter for glass laser processing. The impact of scanning energy and speed on the fabrication of oriented nanocrystals and nanogratings during fs-laser irradiation is studied.Fs-laser direct writing of crystallized lines in both LNS and LNSB glass is investigated using both optical and electron microscopy techniques. Among the main findings to highlight, we observed the possibility to maintain crystallization during scanning at speeds ~5 times higher in LNSB relative to LNS (up to ~600 µm/s in our experimental conditions). We found a speed regime where lines exhibited a large polarization-controlled retardance response (up to 200 nm in LNSB), which is attributed to the texturation of the crystal/glass phase separation with a low scattering level. These characteristics are regarded as assets for future elaboration methods and designs of photonic devices involving crystallization. Finally, by using temperature and irradiation time variations along the main laser parameters (pulse energy, pulse repetition rate, scanning speed), we propose an explanation on the origin of (1) crystallization limitation upon scanning speed, (2) laser track width variation with respect to scanning speed, and (3) narrowing of the nanogratings volume but not the heat-affected volume.
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Navin, Michael J., and Michael D. Morris. "Capillary Electrophoresis Separation Techniques and Mechanisms in Dilute Polymer Matrices." Journal of the Chinese Chemical Society 42, no. 1 (February 1995): 5–9. http://dx.doi.org/10.1002/jccs.199500002.
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Stepanova, Mariia, Aleksei Eremin, Ilia Averianov, Iosif Gofman, Antonina Lavrentieva, Viktor Korzhikov-Vlakh, and Evgenia Korzhikova-Vlakh. "Comparison of Supermacroporous Polyester Matrices Fabricated by Thermally Induced Phase Separation and 3D Printing Techniques." Key Engineering Materials 822 (September 2019): 277–83. http://dx.doi.org/10.4028/www.scientific.net/kem.822.277.
Повний текст джерелаАнотація:
Supermacroporous three-dimensional matrices based on poly-D,L-lactide or polycaprolactone were fabricated by thermally induced phase separation method and 3D printing technique. The morphology and mechanical properties of the resulting matrices were studied with the use of optical and scanning electron microscopy and the uniaxial compression test, respectively. All matrices were characterized with supermacroporous structure suitable for cell penetration. A significant increase in Young's modulus and tensile strength was established for both polymer matrices prepared by 3D printing technique.
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Hsu, S. h., S. Huang, Y. C. Wang, and Y. C. Kuo. "Novel nanostructured biodegradable polymer matrices fabricated by phase separation techniques for tissue regeneration." Acta Biomaterialia 9, no. 6 (June 2013): 6915–27. http://dx.doi.org/10.1016/j.actbio.2013.02.012.
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López-Cabeza, Rocío, and Antonio Francioso. "Chiral Pesticides with Asymmetric Sulfur: Extraction, Separation, and Determination in Different Environmental Matrices." Separations 9, no. 2 (January 26, 2022): 29. http://dx.doi.org/10.3390/separations9020029.
Повний текст джерелаАнотація:
Chiral pesticides with S atoms as asymmetric centers are gaining great importance in the search for new pesticides with new modes of action. As for the rest of the chiral pesticides, the determination of the stereoisomers separately has become crucial in the environmental risks assessment of these pesticides. Therefore, the development of suitable extraction and clean-up methods as well as efficient stereoselective analytical techniques for stereoisomers determination in environmental samples is essential. Currently, liquid/solid phase extraction, microextraction, and QuEChERS-based methods are most commonly used to obtain chiral pesticides from environmental samples. Gas, liquid, and supercritical fluid chromatography together with capillary electrophoresis techniques are the most important for the determination of the stereoisomers of chiral pesticides containing S atoms in its structure. In this study, all these techniques are briefly reviewed, and the advantages and disadvantages of each are discussed.
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Miao, Yu, Tao Long, Jingjun Wang, Fu Lai, Weiran Zuo, and Bao Guo. "The Inadvertent Activation of Silicate Minerals Flotation and Their Depression in Molybdenite Beneficiation." Minerals 11, no. 11 (November 22, 2021): 1296. http://dx.doi.org/10.3390/min11111296.
Повний текст джерелаАнотація:
The Wushan Operation has been studied as a case study, particularly relevant to the copper-molybdenum separation circuit, in which efforts have been made to improve the quality of the molybdenum concentrate through diagnostic analysis. A key finding has been the appearance of coarser silicate minerals in the molybdenum concentrate due to their inadvertent activation in flotation. The suitable silicate minerals flotation conditions occurs, most likely, due to upstream bulk flotation regarding the usage of novel collectors and metal cations bearing process water. The flotation of silicate minerals can be diminished by the implementation of water glass and regrinding. The mechanisms underlying flotation behaviors have been revealed by using advanced in-situ surface analysis and particle size analysis techniques.
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Eikenberg, J., S. Bajo, I. Zumsteg, M. Reuthi, and H. Beer. "Separation and Measurement Techniques for Determination of 228Th, 230Th and 232Th in Various Matrices." Radiation Protection Dosimetry 97, no. 2 (October 1, 2001): 127–31. http://dx.doi.org/10.1093/oxfordjournals.rpd.a006649.
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Raks, Victoria, Hossam Al-Suod, and Bogusław Buszewski. "Isolation, Separation, and Preconcentration of Biologically Active Compounds from Plant Matrices by Extraction Techniques." Chromatographia 81, no. 2 (September 22, 2017): 189–202. http://dx.doi.org/10.1007/s10337-017-3405-0.
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Tohry, Arash, Reza Dehghan, Saeed Chehreh Chelgani, Jan Rosenkranz, and Omid Rahmani. "Selective Separation of Hematite by a Synthesized Depressant in Various Scales of Anionic Reverse Flotation." Minerals 9, no. 2 (February 20, 2019): 124. http://dx.doi.org/10.3390/min9020124.
Повний текст джерелаАнотація:
Demand for high-quality iron concentrate is significantly increasing around the world. Thus, the development of the techniques for a selective separation and rejection of typical associated minerals in the iron oxide ores, such as phosphorous minerals (mainly apatite group), is a high priority. Reverse anionic flotation by using sodium silicate (SS) as an iron oxide depressant is one of the techniques for iron ore processing. This investigation is going to present a synthesized reagent “sodium co-silicate (SCS)” for hematite depression through a reverse anionic flotation. The main hypothesis is the selective depression of hematite and, simultaneously, modification of the pulp pH by SCS. Various flotation experiments, including micro-flotation, and batch flotation of laboratory and industrial scales, were conducted in order to compare the depression selectivity of SS versus SCS. Outcomes of flotation tests at the different flotation scales demonstrated that hematite depression by SCS is around 3.3% higher than by SS. Based on flotation experiment outcomes, it was concluded that SCS can modify the pH of the process at ~9.5, and the plant reagents (including NaOH, Na2CO3, and SS gel) can be replaced by just SCS, which can also lead to a higher efficiency in the plant.
Дисертації з теми "Separation techniques for silicate matrices"
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Wahlen, Raimund. "Development of analytical techniques for the extraction, separation and determination of organometallic and inorganic metal species in environmental and biological matrices." Thesis, Kingston University, 2003. http://eprints.kingston.ac.uk/20722/.
Повний текст джерелаАнотація:
Existing methodologies for the separation and detection of organotin species by liquid- and gas-chromatography coupled to inductively coupled plasma mass-spectrometry (ICP-MS) have been improved significantly. The LC separation of dibutyltin (DBT), triphenyltin (TPhT) and unidentified species in mussel tissue has been enhanced in terms of peak shape and resolution. GC-ICP-MS detection limits for organotin species are significantly reduced by addition of oxygen or nitrogen to the ICP-MS carrier gas. A comparison of LC-ICP-MS and GC-ICP-MS for the species-specific isotope dilution determination of tributyltin (TBT) in sediment extracts has shown that both methods deliver accurate results. However, GC-ICP-MS is significantly more sensitive (absolute detection limit of 0.03 pg TBT as Sn compared to 3 pg TBT as Sn by LC-ICP-MS) and provides superior isotope ratio measurement precision, which is linked to more reproducible peak integration and greater analyte signals by this technique. [sup]117Sn enriched DBT and TBT have been used to investigate the stability of species during extraction and the derivatisation efficiency of ethylation. The speciation of arsenic (As) has been performed using anion-exchange chromatography coupled to ICP-MS detection. Good separations have been achieved for up to seven species including monomethyl- and dimethylarsinic acid (MMA and DMA) and especially between arsenobetaine (AsB) and arsenite (As(III)). The accuracy and precision of the methods have been tested by analysis of a range of biological certified reference materials. Extraction methods for organotin and arsenic species have been developed using accelerated solvent extraction (ASE), and this technique has been assessed for the simultaneous co-extraction of Sn, As and Hg species from environmental samples. Accurate data were obtained for DBT, TBT, AsB and DMA in a certified oyster tissue, and promising results were also obtained for methylmercury. The combined extraction, separation and detection methods have been used to determine the vertical profiles of organotin and arsenic species in sediments from the Thames estuary (UK). Vp to nine organotin species were detected, with DBT being the predominant at levels ranging from [tilde] 12 - 160 ng/g (as Sn). The main As species were As(III) and As(V) at concentrations between [tilde] 160 - 4200 ng/g (as As). Methylated arsenicals were also detected throughout the core.
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Filippi, Marc. "Séparation de sources en imagerie nucléaire." Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAT025/document.
Повний текст джерелаАнотація:
En imagerie nucléaire (scintigraphie, TEMP, TEP), les diagnostics sont fréquemment faits à l'aide des courbes d'activité temporelles des différents organes et tissus étudiés. Ces courbes représentent l'évolution de la distribution d'un traceur radioactif injecté dans le patient. Leur obtention est compliquée par la superposition des organes et des tissus dans les séquences d'images 2D, et il convient donc de séparer les différentes contributions présentes dans les pixels. Le problème de séparation de sources sous-jacent étant sous-déterminé, nous proposons d'y faire face dans cette thèse en exploitant différentes connaissances a priori d'ordre spatial et temporel sur les sources. Les principales connaissances intégrées ici sont les régions d'intérêt (ROI) des sources qui apportent des informations spatiales riches. Contrairement aux travaux antérieurs qui ont une approche binaire, nous intégrons cette connaissance de manière robuste à la méthode de séparation, afin que cette dernière ne soit pas sensible aux variations inter et intra-utilisateurs dans la sélection des ROI. La méthode de séparation générique proposée prend la forme d'une fonctionnelle à minimiser, constituée d'un terme d'attache aux données ainsi que de pénalisations et de relâchements de contraintes exprimant les connaissances a priori. L'étude sur des images de synthèse montrent les bons résultats de notre approche par rapport à l'état de l'art. Deux applications, l'une sur les reins, l'autre sur le cœur illustrent les résultats sur des données cliniques réellesIn nuclear imaging (scintigraphy, SPECT, PET), diagnostics are often made with time activity curves (TAC) of organs and tissues. These TACs represent the dynamic evolution of tracer distribution inside patient's body. Extraction of TACs can be complicated by overlapping in the 2D image sequences, hence source separation methods must be used in order to extract TAC properly. However, the underlying separation problem is underdetermined. We propose to overcome this difficulty by adding some spatial and temporal prior knowledge about sources on the separation process. The main knowledge used in this work is region of interest (ROI) of organs and tissues. Unlike state of the art methods, ROI are integrated in a robust way in our method, in order to face user-dependancy in their selection. The proposed method is generic and minimize an objective function composed with a data fidelity criterion, penalizations and relaxations expressing prior knowledge. Results on synthetic datasets show the efficiency of the proposed method compare to state of the art methods. Two clinical applications on the kidney and on the heart are also adressed
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Lowczak, C. R. "Copper isotope method development for determining the source of mineralised provinces." Thesis, 2019. https://hdl.handle.net/2440/136974.
Повний текст джерелаАнотація:
This item is only available electronically.Many isotope proxies have been applied to study the prosperous iron oxide copper gold (IOCG) province in the eastern Gawler Craton (E.G.C) and Au mineralised region of the cental Gawler Craton (C.G.C), in Southern Australia. Yet, copper isotope proxies- an indicator for low temperature fluid flow and sulfide mineralisation- have yet to be applied to the region. In this study, purification techniques using automatic column chromatography were demonstrated during separation of Cu from matrix elements. Cu isotopes – 65Cu & 63Cu – were used to understand the extent of mantle input and mantle metasomatism, potentially responsible for the Cu in IOCG mineralisation. Eleven samples were gathered. Three mafic enclaves and four intrusives from the Central Gawler Gold Province and four intrusives from the eastern Gawler IOCG province. Separation using automatic column chromatography proved challenging, with matrix elements abundant throughout the purified fractions (Co, Ti, Fe, Mg, Na), due to poor separation. Ti proved to a major interference during isotopic analysis using a Multicollector-ICP-MS, positively offsetting values. E.C.G samples showed the most positively fractionated δ65Cu values (+0.69 ± 0.024‰ to +1.422 ± 0.077‰). Enclaves from the C.G.C showed the most negatively fractionated δ65Cu values (-0.053 ± 0.023‰ to -0.897 ± 0.006‰), while intrusives from this region showed more positive δ65Cu values (+0.084±0.23‰ to +0.397±0.011‰). All samples showed a lack of hydrothermal alteration. Magmatic sulphide-containing E.G.C samples had the most positive δ65Cu values; which cannot be explained by current understanding of Cu isotope fractionation during sulfide saturation. This trend may instead be attributed to a heterogeneous sub-continental lithospheric mantle (SCLM) source. In contrast the negative δ65Cu values of mafic enclaves is possibly caused by assimilation of S-type granitic crust and/or possibly due to a heterogeneous SCLM source.
Thesis (B.Sc.(Hons)) -- University of Adelaide, School of Physical Sciences, 2019
Частини книг з теми "Separation techniques for silicate matrices"
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Hale, Robert C., Meredith E. Seeley, Ashley E. King, and Lehuan H. Yu. "Analytical Chemistry of Plastic Debris: Sampling, Methods, and Instrumentation." In Microplastic in the Environment: Pattern and Process, 17–67. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-78627-4_2.
Повний текст джерелаАнотація:
AbstractApproaches for the collection and analysis of plastic debris in environmental matrices are rapidly evolving. Such plastics span a continuum of sizes, encompassing large (macro-), medium (micro-, typically defined as particles between 1 μm and 5 mm), and smaller (nano-) plastics. All are of environmental relevance. Particle sizes are dynamic. Large plastics may fragment over time, while smaller particles may agglomerate in the field. The diverse morphologies (fragment, fiber, sphere) and chemical compositions of microplastics further complicate their characterization. Fibers are of growing interest and present particular analytical challenges due to their narrow profiles. Compositional classes of emerging concern include tire wear, paint chips, semisynthetics (e.g., rayon), and bioplastics. Plastics commonly contain chemical additives and fillers, which may alter their toxicological potency, behavior (e.g., buoyancy), or detector response (e.g., yield fluorescence) during analysis. Field sampling methods often focus on >20 μm and even >300 μm sized particles and will thus not capture smaller microplastics (which may be most abundant and bioavailable). Analysis of a limited subgroup (selected polymer types, particle sizes, or shapes) of microplastics, while often operationally necessary, can result in an underestimation of actual sample content. These shortcomings complicate calls for toxicological studies of microplastics to be based on “environmentally relevant concentrations.” Sample matrices of interest include water (including wastewater, ice, snow), sediment (soil, dust, wastewater sludge), air, and biota. Properties of the environment, and of the particles themselves, may concentrate plastic debris in select zones (e.g., gyres, shorelines, polar ice, wastewater sludge). Sampling designs should consider such patchy distributions. Episodic releases due to weather and anthropogenic discharges should also be considered. While water grab samples and sieving are commonplace, novel techniques for microplastic isolation, such as continuous flow centrifugation, show promise. The abundance of nonplastic particulates (e.g., clay, detritus, biological material) in samples interferes with microplastic detection and characterization. Their removal is typically accomplished using a combination of gravity separation and oxidative digestion (including strong bases, peroxide, enzymes); unfortunately, aggressive treatments may damage more labile plastics. Microscope-based infrared or Raman detection is often applied to provide polymer chemistry and morphological data for individual microplastic particles. However, the sheer number of particles in many samples presents logistical hurdles. In response, instruments have been developed that employ detector arrays and rapid scanning lasers. The addition of dyes to stain particulates may facilitate spectroscopic detection of some polymer types. Most researchers provide microplastic data in the form of the abundances of polymer types within particle size, polymer, and morphology classes. Polymer mass data in samples remain rare but are essential to elucidating fate. Rather than characterizing individual particles in samples, solvent extraction (following initial sample prep, such as sediment size class sorting), combined with techniques such as thermoanalysis (e.g., pyrolysis), has been used to generate microplastic mass data. However, this may obviate the acquisition of individual particle morphology and compositional information. Alternatively, some techniques (e.g., electron and atomic force microscopy and matrix-assisted laser desorption mass spectrometry) are adept at providing highly detailed data on the size, morphology, composition, and surface chemistry of select particles. Ultimately, the analyst must select the approach best suited for their study goals. Robust quality control elements are also critical to evaluate the accuracy and precision of the sampling and analysis techniques. Further, improved efforts are required to assess and control possible sample contamination due to the ubiquitous distribution of microplastics, especially in indoor environments where samples are processed.
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Cutler, P. "Chromatography on the basis of size." In Protein Purification Techniques. Oxford University Press, 2001. http://dx.doi.org/10.1093/oso/9780199636747.003.0012.
Повний текст джерелаАнотація:
Chromatography has been employed for the separation of proteins and other biological macromolecules on the basis of molecular size since the mid 1950s when Lathe and Rutheven employed modified starch as a media for separation. Porath and Flodin developed the technique further using cross-linked dextran and coined the term gel filtration. Some confusion over nomenclature has been created by the term gel permeation, used to describe separation by the same principle in organic mobile phases using synthetic matrices. It is now generally agreed that the terms gel filtration and gel permeation do not accurately reflect the nature of the separation. Size exclusion Chromatography (SEC) has been widely accepted as a universal description of the technique and in line with the IUPAC nomenclature this term will be adopted. The historical development of SEC for protein separation has been reviewed. SEC is a commonly used technique due to the diversity of the molecular sizes of proteins in biological tissues and extracts. In addition to isolating proteins from crude mixtures, SEC has been employed for many roles including buffer exchange (desalting), removal of non-protein contaminants (DNA, viruses), protein aggregate removal, the study of biological interactions, and protein folding. The principle of size exclusion is based on a solid phase matrix consisting of beads of defined porosity which are packed into a column through which a mobile liquid phase flows. The mobile phase has access to both the volume inside the pores and the volume external to the beads. Unlike many other chromatographic procedures size exclusion is not an adsorption technique. Separation can be visualized as reversible partitioning into the two liquid volumes. The elution time is dependent upon an individual protein’s ability to access the pores of the matrix. Large molecules remain in the volume external to the beads as they are unable to enter the pores. The resulting shorter flow path means that they pass through the column relatively rapidly, emerging early. Proteins that are excluded from the pores completely, elute in the void volume, V0. This is often determined experimentally by the use of a high molecular weight component such as blue dextran or calf thymus DNA.
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Wells, David E., and Philipp Hess. "Chapter 2 Separation, clean-up and recoveries of persistent trace organic contaminants from soils, sediment and biological matrices." In Sample handling and trace analysis of pollutants - Techniques, applications and quality assurance, 73–113. Elsevier, 2000. http://dx.doi.org/10.1016/s0167-9244(00)80008-6.
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Zia Uddin Kamal, Mohammed, and Md Yunus Miah. "Arsenic Speciation Techniques in Soil Water and Plant: An Overview." In Arsenic [Working Title]. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.99273.
Повний текст джерелаАнотація:
There are more than 100 different arsenic with different characteristics in the soil-water-plant ecosystem. The identification and quantification of individual arsenic species is essential for understanding the distribution, environmental fate and behavior, metabolism and toxicity of arsenic. Due to the hazardous nature of arsenic, people have a high interest in the measurement of arsenic species. The reaction of the formation of arsenic speciation in the soil-water-plant environment is briefly studied. There is little information on methods used to quantify arsenic forms and species in contaminated soil, water and plant. The purpose of this article is to understand the available sample pretreatment, extraction, separation, detection and method validation techniques for arsenic speciation analysis of arsenic species in soil, water and plant. The performances of various sample preparation and extraction processes, as well as effective separation techniques, that contribute greatly to excellent sensitivity and selectivity in arsenic speciation when coupling with suitable detection mode, and method validity are discussed. The outlines of arsenic speciation techniques are discussed in view of the importance to the completeness and accuracy of analytical data in the soil-water-plant samples. To develop cheap, fast, sensitive, and reproducible techniques with low detection limits, still needed to confine research on arsenic speciation present in environmental matrices.
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Abbas, Mateen. "Chromatographic Techniques for Estimation of Aflatoxins in Food Commodities." In Aflatoxins [Working Title]. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.98508.
Повний текст джерелаАнотація:
Aflatoxins, produced mainly by Aspergillus flavus Aspergillus parasiticus, have been documented as one of the major food contaminants throughout the world. Because of their toxic nature, these food contaminants have acknowledged considerable attention in recent years. Among the different types of Aflatoxins, the most prevalent and predominant Aflatoxins are AFB1, AFB2, AFG1, AFG2, AFM1, AFM2 which are considered the more lethal as compared to others. Several analytical and immunological methods are available for testing and estimating aflatoxins in different food commodities. However, chromatographic techniques have been considered superior regarding the estimation of aflatoxins both qualitatively and quantitatively. Chromatographic techniques have numerous applications for the separation and identification of chemical and biological compounds in food industry. It has grown to be the most popular and versatile of all analytical techniques in laboratories used for the analysis of multiple components in different matrices. For preliminary qualitative detection of Aflatoxins, Thin layer chromatography (TLC) is considered the best analytical technique which is being used broadly in food industry. However, liquid chromatographic techniques including High Performance Liquid Chromatography (HPLC) and Liquid chromatography-mass Spectrometry (LC–MS) are the best analytical techniques developed so far for the quantification of Aflatoxins in food commodities.
Тези доповідей конференцій з теми "Separation techniques for silicate matrices"
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Roach, Jay A. "Investigation of Processing Advanced Waste Forms in Cold Crucible Induction Melter Systems." In ASME 2013 15th International Conference on Environmental Remediation and Radioactive Waste Management. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/icem2013-96077.
Повний текст джерелаАнотація:
The Cold Crucible Induction Melter (CCIM) technology has been identified in several independent reviews and studies as a potential alternative or supplemental vitrification technology for specific U.S. Department of Energy (DOE) high level radioactive waste (HLW) streams. These inventories have unique chemistries, such as high alumina, high iron, high chromium, etc., that are not amenable to efficient immobilization in conventional borosilicate glass (BSG) matrices. Advanced waste forms, such as iron phosphate glass (FePG), high crystalline BSG (HC-BSG), and alumino-silicate glass-ceramic (GC) have been shown to provide significantly improved immobilization matrices for these challenging waste streams, including dramatically improved waste loadings; however, they are difficult to efficiently process in the baseline joule-heated ceramic melters (JHCMs). The CCIM technology can effectively process these advanced waste forms at the desired high waste loadings. This paper describes the most recent collaborative activities between the DOE Office of Environmental Management (DOE-EM) and various Russian institutions in modeling, development and testing of advanced waste forms in CCIMs, including FePG and HC-BSG formulations. Additionally, past interactions with other international partners, including France and Korea, are described. Finally, recent enhancements to CCIM processing related to modeling, draining techniques and automated control, which were collaboratively developed, will be discussed.
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Kögel, Michael, Sebastian Brand, and Frank Altmann. "Machine Learning Assisted Signal Analysis in Acoustic Microscopy for Non-Destructive Defect Identification." In ISTFA 2019. ASM International, 2019. http://dx.doi.org/10.31399/asm.cp.istfa2019p0035.
Повний текст джерелаАнотація:
Abstract Signal processing and data interpretation in scanning acoustic microscopy is often challenging and based on the subjective decisions of the operator, making the defect classification results prone to human error. The aim of this work was to combine unsupervised and supervised machine learning techniques for feature extraction and image segmentation that allows automated classification and predictive failure analysis on scanning acoustic microscopy (SAM) data. In the first part, conspicuous signal components of the time-domain echo signals and their weighting matrices are extracted using independent component analysis. The applicability was shown by the assisted separation of signal patterns to intact and defective bumps from a dataset of a CPU-device manufactured in flip-chip technology. The high success-rate was verified by physical cross-sectioning and high-resolution imaging. In the second part, the before mentioned signal separation was employed to generate a labeled dataset for training and finetuning of a classification model based on a one-dimensional convolutional neural network. The learning model was sensitive to critical features of the given task without human intervention for classification between intact bumps, defective bumps and background. This approach was evaluated on two individual test samples that contained multiple defects in the solder bumps and has been verified by physical inspection. The verification of the classification model reached an accuracy of more than 97% and was successfully applied to an unknown sample which demonstrates the high potential of machine learning concepts for further developments in assisted failure analysis.
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Nottoli, Emmanuelle, Philippe Bienvenu, Didier Bourlès, Alexandre Labet, Maurice Arnold, and Maité Bertaux. "Determination of Long-Lived Radionuclide (10Be, 41Ca, 129I) Concentrations in Nuclear Waste by Accelerator Mass Spectrometry." In ASME 2013 15th International Conference on Environmental Remediation and Radioactive Waste Management. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/icem2013-96054.
Повний текст джерелаАнотація:
Radiological characterization of nuclear waste is essential for storage sites management. However, most of Long-Lived RadioNuclides (LLRN), important for long-term management, are difficult to measure since concentration levels are very low and waste matrices generally complex. In an industrial approach, LLRN concentrations are not directly measured in waste samples but assessed from scaling factors with respect to easily measured gamma emitters. Ideally, the key nuclide chosen (60Co, 137Cs) should be produced by a similar mechanism (fission or activation) as the LLRN of interest and should have similar physicochemical properties. However, the uncertainty on the scaling factors, determined from experimental and/or calculation data, can be quite important. Consequently, studies are performed to develop analytical procedures which would lead to determine precisely the concentration of LLRN in nuclear waste. In this context, the aim of this study was to determine the concentrations of three LLRN: 129I (T1/2 = 15.7×106 a), 41Ca (T1/2 = 9.94×104 a) and 10Be (T1/2 = 1.387×106 a) in spent resins used for primary fluid purification in Pressurized Water Reactors using Accelerator Mass Spectrometry (AMS) for measurement. The AMS technique combined mass spectrometry and nuclear physics to achieve highly efficient molecular and elemental isobars separation. Energies of several Million Electron-Volt transferred to the ions in the first accelerating part of specifically developed tandem accelerators lead to molecular isobars destruction through interaction with the argon gas used to strip the injected negative ions to positive ones. At the exit of the tandem accelerator, the energy acquired in both accelerating parts allows an elemental isobars separation based on their significantly different energy loss (dE) while passing through a thickness of matter dx that is proportional to their atomic number (Z) and inversely proportional to ions velocity (ν) according to the Bethe-Block law (1). (1)dEdx=k*Z2ν2 The use of a particle accelerator in conjunction with a selective ion source, mass and energy filters and a high-performance detector thus allow unambiguously identifying and measuring analyte concentration against much more abundant interfering isobars. The development of AMS and of related applications have recently been extensively reviewed [1–3]. Up to now, the potentialities of the accelerator mass spectrometry technique were explored for the measurement of cosmogenic radionuclides produced in the Earth’s environment either in the atmosphere or in the Earth’s crust (in situ-production). Many applications aiming to date and/or quantify Earth surface processes have been developed in the fields of geology, geomorphology and planetary sciences as well as archeology paleoanthropology and biomedicine. The present study extends the scope of AMS to nuclear industry. Because AMS facilities are not widely accessible and difficult to handle, LLRN concentrations in nuclear waste are usually determined using Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and radiometric techniques. However for the measurement of very low LLRN concentrations, AMS becomes the most effective measurement method with detection limits of 105–106 atoms per sample. In this study, AMS measurements were performed using the French AMS national facility ASTER located at the Centre Européen de Recherche et d’Enseignement des Géosciences de l’Environnement (CEREGE). The challenge was to define a chemical treatment procedure allowing the measurement of the three nuclides, 10Be, 41Ca and 129I, by AMS. Each method selection was based on three main requirements: 1) a quantitative recovery in solution of Be, Ca, I and key radionuclides after resin mineralization, 2) a selective extraction from the sample matrix and the separation from β-γ emitters (3H, 14C, 55Fe, 59Ni, 60Co, 63Ni, 90Sr, 125Sb, 134Cs, 137Cs) and isobars, 3) the precipitation of each element under the best suited forms (i.e. AgI, CaF2, BeO) for AMS measurements. The chosen methods were optimized on synthetic solutions and finally applied for the determination of the three LLRN concentrations in spent resins from a 900 MWe Nuclear Power Reactor.
Звіти організацій з теми "Separation techniques for silicate matrices"
1
Lehotay, Steven J., and Aviv Amirav. Fast, practical, and effective approach for the analysis of hazardous chemicals in the food supply. United States Department of Agriculture, April 2007. http://dx.doi.org/10.32747/2007.7695587.bard.
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Background to the topic: For food safety and security reasons, hundreds of pesticides, veterinary drugs, and environmental pollutants should be monitored in the food supply, but current methods are too time-consuming, laborious, and expensive. As a result, only a tiny fraction of the food is tested for a limited number of contaminants. Original proposal objectives: Our main original goal was to develop fast, practical, and effective new approaches for the analysis of hazardous chemicals in the food supply. We proposed to extend the QuEChERS approach to more pesticides, veterinary drugs and pollutants, further develop GC-MS and LC-MS with SMB and combine QuEChERS with GC-SMB-MS and LC-SMB-EI-MS to provide the “ultimate” approach for the analysis of hazardous chemicals in food. Major conclusions, solutions and achievements: The original QuEChERS method was validated for more than 200 pesticide residues in a variety of food crops. For the few basic pesticides for which the method gave lower recoveries, an extensive solvent suitability study was conducted, and a buffering modification was made to improve results for difficult analytes. Furthermore, evaluation of the QuEChERS approach for fatty matrices, including olives and its oil, was performed. The QuEChERS concept was also extended to acrylamide analysis in foods. Other advanced techniques to improve speed, ease, and effectiveness of chemical residue analysis were also successfully developed and/or evaluated, which include: a simple and inexpensive solvent-in-silicone-tube extraction approach for highly sensitive detection of nonpolar pesticides in GC; ruggedness testing of low-pressure GC-MS for 3-fold faster separations; optimization and extensive evaluation of analyte protectants in GC-MS; and use of prototypical commercial automated direct sample introduction devices for GC-MS. GC-MS with SMB was further developed and combined with the Varian 1200 GCMS/ MS system, resulting in a new type of GC-MS with advanced capabilities. Careful attention was given to the subject of GC-MS sensitivity and its LOD for difficult to analyze samples such as thermally labile pesticides or those with weak or no molecular ions, and record low LOD were demonstrated and discussed. The new approach of electron ionization LC-MS with SMB was developed, its key components of sample vaporization nozzle and flythrough ion source were improved and was evaluated with a range of samples, including carbamate pesticides. A new method and software based on IAA were developed and tested on a range of pesticides in agricultural matrices. This IAA method and software in combination with GC-MS and SMB provide extremely high confidence in sample identification. A new type of comprehensive GCxGC (based on flow modulation) was uniquely combined with GC-MS with SMB, and we demonstrated improved pesticide separation and identification in complex agricultural matrices using this novel approach. An improved device for aroma sample collection and introduction (SnifProbe) was further developed and favorably compared with SPME for coffee aroma sampling. Implications, both scientific and agricultural: We succeeded in achieving significant improvements in the analysis of hazardous chemicals in the food supply, from easy sample preparation approaches, through sample analysis by advanced new types of GC-MS and LCMS techniques, all the way to improved data analysis by lowering LOD and providing greater confidence in chemical identification. As a result, the combination of the QuEChERS approach, new and superior instrumentation, and the novel monitoring methods that were developed will enable vastly reduced time and cost of analysis, increased analytical scope, and a higher monitoring rate. This provides better enforcement, an added impetus for farmers to use good agricultural practices, improved food safety and security, increased trade, and greater consumer confidence in the food supply.