Articoli di riviste: "Quantification de phases minérales"

1

Cabanes, Nelly, e Jean-Claude Mercier. "Chimie des phases minérales et conditions d'équilibre des enclaves de lherzolite à spinelle de Montferrier (Hérault, France)". Bulletin de Minéralogie 111, n. 1 (1988): 65–77. http://dx.doi.org/10.3406/bulmi.1988.8071.

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Breda, M., S. A. Ontiveros Vidal, Jacopo Basoni e Irene Calliari. "Phases Quantification in Duplex Stainless Steels Weldments". Applied Mechanics and Materials 698 (dicembre 2014): 209–14. http://dx.doi.org/10.4028/www.scientific.net/amm.698.209.

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Duplex Stainless Steels (DSS) are very attractive steels and their application is presently of increasing interest, especially as structural materials in aggressive environments. DSS are austeno-ferritic biphasic steels, having an austenite-to-ferrite phase ratio of about one, giving the best combination of mechanical and corrosion-resistance properties. However, these steels must be handled with extreme care, especially if thermal cycles are involved, owing to the formation of dangerous secondary compounds that highly worsen their excellent properties.The production of big pipes requires manufacturing welding operations on steel plates or sheets and the final products must satisfy specific requirements in terms of material properties. DSS approximately contain equal volume fraction of the phases that, in practice, cover a slightly wider range within 40/60 and 60/40. Therefore, since DSS properties depend on phase ratio, ferrite quantification on an industrial scale represents a topic of great interest, which must be as reliable as possible and, at the same time, quickly executable.The present paper gives a comparison of different methods currently employed for ferrite determination in DSS weldments, in order to understand the limits derived from the specific employed technique.

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Scarlett, Nicola V. Y., e Ian C. Madsen. "Quantification of phases with partial or no known crystal structures". Powder Diffraction 21, n. 4 (dicembre 2006): 278–84. http://dx.doi.org/10.1154/1.2362855.

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Quantification of mixtures via the Rietveld method is generally restricted to crystalline phases for which structures are well known. Phases that have not been identified or fully characterized may be easily quantified as a group, along with any amorphous material in the sample, by the addition of an internal standard to the mixture. However, quantification of individual phases that have only partial or unknown structures is carried out less routinely. This paper presents methodology for quantification of such phases. It outlines the procedure for calibration of the method and gives detailed examples from both synthetic and mineralogical systems. While the method should, in principle, be generally applicable, its implementation in the TOPAS program from Bruker AXS is demonstrated here.

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Medina-Hernández, M. J., e S. Sagrado. "Chromatographic quantification of hydrophobicity using micellar mobile phases". Journal of Chromatography A 718, n. 2 (dicembre 1995): 273–82. http://dx.doi.org/10.1016/0021-9673(95)00678-8.

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Bergounioux, C., C. Perennes, P. Gadal e S. C. Brown. "Nuclear RNA quantification in protoplast cell-cycle phases". Cytometry 9, n. 1 (gennaio 1988): 84–87. http://dx.doi.org/10.1002/cyto.990090113.

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Locat, Jacques, e Marc-André Bérubé. "L’influence de la granulométrie sur la mesure des carbonates par la méthode du Chittick". Note 40, n. 3 (4 dicembre 2007): 331–36. http://dx.doi.org/10.7202/032653ar.

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RÉSUMÉ Des études récentes sur la composition minéralogique de sédiments argileux de la vallée du Saint-Laurent incluaient l'utilisation de la méthode du Chittick pour la détermination des quantités respectives de calcite et de dolomite. Lors d'essais préliminaires de calibration, il est apparu que la granulométrie de ces phases minérales pouvait grandement influencer les résultats. Afin de quantifier ce problème, plusieurs échantillons de granulométrie variée et contrôlée ont été dosés. La méthode du Chittick s'avéra alors très bonne pour le dosage de la teneur totale en carbonates mais faible pour le dosage individualisé de la calcite et de la dolomite en raison de sa forte sensibilité à la granulométrie des carbonates et à leur surface spécifique. Ainsi, les échantillons de dolomite pure ont montré une teneur apparente en calcite de 15 à 66%, selon leur granulométrie. L'addition d'une analyse chimique de la solution résiduelle obtenue au terme de l'essai permet toutefois d'obtenir les concentrations réelles de ces deux carbonates.

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Leduc, Thierry, Éric Goemaere, Ivan Jadin e Pierre Cattelain. "L’altération des briquets en « marcassite » du « Trou de Chaleux » (Fouilles d'Édouard Dupont) : identification des phases minérales primaires et secondaires". ArchéoSciences, n. 36 (31 dicembre 2012): 85–93. http://dx.doi.org/10.4000/archeosciences.3776.

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Dauphin, Yannicke. "Comparaison de l'état de conservation des phases minérales et organiques d'os fossiles. Implications pour les reconstitutions paléoenvironnementales et phylétiques". Annales de Paléontologie 84, n. 2 (aprile 1998): 215–39. http://dx.doi.org/10.1016/s0753-3969(98)80006-2.

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9

Escuder-Gilabert, L., Y. Martín-Biosca, R. M. Villanueva-Camañas, M. J. Medina-Hernández e S. Sagrado. "The chromatographic quantification of hydrophobicity using micellar mobile phases". Chromatographia 50, n. 5-6 (settembre 1999): 325–32. http://dx.doi.org/10.1007/bf02490837.

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Mishra, R. "Quantification of Galvannealed Coating Phases Using the Galvanostatic Technique". Metallurgical and Materials Transactions A 39, n. 10 (11 luglio 2008): 2275–77. http://dx.doi.org/10.1007/s11661-008-9592-4.

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AL-Farhan, Khalid A. "farhan—a qualitative and quantitative PC program for X-ray powder diffraction". Powder Diffraction 14, n. 1 (marzo 1999): 16–21. http://dx.doi.org/10.1017/s0885715600010241.

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FARHAN is a PC interactive, graphically oriented search–match–identification–quantification computer program for X-ray powder diffraction, which uses a variable intensity-error window (IEW). Both the intensity scale factor and the IEW for each standard phase are estimated by a simple iterative procedure. A new tunable combined figure-of-merit (agreement function) is suggested for estimating the goodness-of-fit of matches. The concentrations of the identified phases may be determined by normalized or generalized RIR quantification methods, if the RIRs of the identified phases are known.

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Kniess, C. T., P. B. Prates, J. C. de Lima, N. C. Kuhnen, Humberto Gracher Riella e A. M. Maliska. "Quantitative Determination of the Crystalline Phases of the Ceramic Materials Utilizing the Rietveld Method". Materials Science Forum 660-661 (ottobre 2010): 164–69. http://dx.doi.org/10.4028/www.scientific.net/msf.660-661.164.

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Ceramic materials have properties defined by their chemical and micro-structural composition. The quantification of the crystalline phases is a fundamental stage in the determination of the structure, properties and applications of a ceramic material. Within this context, this study aims is the quantitative determination of the crystalline phases of the ceramic materials developed with addition of mineral coal bottom ash, utilizing the X ray diffraction technique, through the method proposed by Rietveld. For the formulation of the ceramic mixtures a {3,3} simplex-lattice design was used, giving ten formulations of three components (two different types of clays and coal bottom ash). The crystalline phases identified in the ceramic materials after sintering at 1150oC during two hours are: quartz, tridimite, mullite and hematite. The proposed methodology utilizing the Rietveld method for the quantification relating to crystalline phases of the materials was shown to be adequate and efficient.

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Harnett, L., M. Stennett, E. Maddrell e N. Hyatt. "Characterisation of glass ceramic wasteforms using quantitative image analysis of electron micrographs". MRS Advances 7, n. 5-6 (9 febbraio 2022): 86–89. http://dx.doi.org/10.1557/s43580-022-00227-0.

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Abstract Multi-phase material systems make up a significant proportion of the currently proposed and researched wasteforms for sequestration of heterogeneous nuclear material feeds. Quantification of the components for such multi-phase assemblages is typically performed using diffraction-based Rietveld methods, many of which necessitate long measurement times of several hours. Furthermore, careful additions of an internal standard are typically required, to facilitate inclusion of amorphous phases in the quantification. The application of an image analysis method has been investigated, using the z-contrast greyscale of back-scattered electron micrographs to determine the relative quantities of component phases in a suite of monolithic phosphate glass ceramic wasteforms. This work demonstrates an alternate methodology for accelerated quantification which could be applied to other heterogeneous wasteforms and multi-phase materials. Graphical abstract

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14

Wilson, A. S., K. A. Christofidou, A. Evans, M. C. Hardy e H. J. Stone. "Comparison of Methods for Quantification of Topologically Close-Packed Phases in Ni-Based Superalloys". Metallurgical and Materials Transactions A 50, n. 12 (15 ottobre 2019): 5925–34. http://dx.doi.org/10.1007/s11661-019-05442-3.

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Abstract The ability to quantify accurately the formation of topologically close-packed phases in nickel-based superalloys is key to assessing their thermal stability and ensuring that their performances will not deteriorate during long-term exposure at high temperatures. To investigate the effectiveness of synchrotron XRD for the detection of such minority phases in Ni-based superalloys, the commercial polycrystalline alloy RR1000 was analyzed following exposures of varying times at 800 °C. Data were collected from both solid samples and extracted residues, and additional laboratory X-ray diffraction was performed on the residues. The minor phases were successfully detected in solid samples using synchrotron radiation, and a comparison of the results from these quantification methods shows that the extraction method gives results of the right order of magnitude to reflect the phase quantities that are present in the alloy. However, the results indicate that the synchrotron route is not a suitable method for the quantification of phases present in quantities less than approximately 0.3 wt pct.

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Muthalib, Nurhidayah, Norazharuddin Shah Abdullah, Hashim Hussin e Suhaina Ismail. "Mineralogical Characteristics and Quantification of Mineral Phases in Malaysian Low Grade Manganese Ore". Materials Science Forum 888 (marzo 2017): 453–57. http://dx.doi.org/10.4028/www.scientific.net/msf.888.453.

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The aim of this work is to study the quantification of crystalline and amorphous content of manganese ore. The mineralogical characteristics and mineral phases of Malaysian low grade manganese ore are investigated using spiking method technique. Manganese ore was mixed with an internal standard of rutile and analyzed by Rietveld refinement with SIROQUANT. The refinement qualification and quantification indicated three phases which are pyrolusite (MnO2) with 1.1%, goethite (α-FeOOH) with 0.5% and quartz (SiO2) with 30.9%. From the calculation, sample consisted more amorphous content which is 0.6 compared to crystalline (0.4). This revealed that the ore is in amorphous form.

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Miquita, D. R., J. C. González, M. I. N. da Silva, W. N. Rodrigues, M. V. B. Moreira, R. Paniago, R. Ribeiro-Andrade, R. Magalhães-Paniago, H. D. Pfannes e A. G. de Oliveira. "Identification and quantification of iron silicide phases in thin films". Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films 26, n. 5 (settembre 2008): 1138–48. http://dx.doi.org/10.1116/1.2953708.

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Fourati, Slim, e Jean-Michel Pawlotsky. "Recent advances in understanding and diagnosing hepatitis B virus infection". F1000Research 5 (6 settembre 2016): 2243. http://dx.doi.org/10.12688/f1000research.8983.1.

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Hepatitis B virus (HBV) infects approximately 240 million individuals worldwide. Recent advances in the virology, immunopathogenesis, and diagnosis of HBV infection are summarized in this review article. The identification of a hepatocyte-specific cellular receptor for HBV, the sodium taurocholate co-transporting polypeptide (NTCP), made it possible to develop reliable cell culture systems and better understand the early steps of the viral lifecycle. Viral and host factors involved in covalently closed circular DNA synthesis, stability, and transcriptional regulation have also been identified and provide potential targets for new drugs. Based on recent evidence showing trained immunity in immune-tolerant patients, the immune tolerance and immune clearance phases have been renamed the non-inflammatory and inflammatory phases, respectively. New diagnostic and monitoring tools are now available, including rapid diagnostic tests for hepatitis B surface antigen (HBsAg) detection, HBsAg quantification assays, anti-HBc antibody quantification assays, an HBV core-related antigen (HBcrAg) quantification test, new HBV DNA detection and quantification assays, and an HBV RNA quantification test. Their clinical utility is under study. Finally, new antiviral and immune modulation approaches are in the preclinical or early clinical developmental stages, with the goal to achieve functional cure or ideally (if possible) eradication of HBV infection.

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Regnault, Olivier, Vincent Lagneau, Hubert Catalette e Hélène Schneider. "Étude expérimentale de la réactivité du CO2 supercritique vis-à-vis de phases minérales pures. Implications pour la séquestration géologique de CO2". Comptes Rendus Geoscience 337, n. 15 (novembre 2005): 1331–39. http://dx.doi.org/10.1016/j.crte.2005.07.012.

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Valášková, Marta, Zdeněk Klika, Boris Novosad e Bedřich Smetana. "Crystallization and Quantification of Crystalline and Non-Crystalline Phases in Kaolin-Based Cordierites". Materials 12, n. 19 (23 settembre 2019): 3104. http://dx.doi.org/10.3390/ma12193104.

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Kaolin is most often used as traditional raw material in ceramic industry. The purpose of the study was to obtain understanding of the structural and chemical variability of cordierite ceramics influenced by chemical and mineralogical properties of six raw kaolins taken from different localities when they are applied in ceramics mixtures with vermiculite and sintered up to 1300 °C. The X-ray diffraction and simultaneous thermogravimetric and differential thermal analysis were used to identify and characterize crystalline mineral phases and the course of reactions during the heating. The percentages of the crystalline and non-crystalline phases were newly determined by recalculation of the bulk chemical analyses of kaolins and cordierite ceramics using Chemical Quantitative Mineral Analysis (CQMA) method. Varying amounts of minerals in kaolins: kaolinite from 73.3 to 85.0, muscovite from 4.2 to 9.9, and quartz from 6.0 to 19.5 (mass %) affected amount of cordierite/indialite from 75.2 to 85.1, enstatite from 5.8 to 8.9 (when are calculated as their maximal possible percentages), and non-crystalline phases from 8.8 to 15.1 (mass %) in cordierite ceramics. Regression analysis predicted high relationship between quantity of: (a) kaolinite in kaolins and crystalline cordierite and (b) quartz in kaolins and non-crystalline phases in the ceramics. The migration of potassium from muscovite into the cordierite structure, melting point and crystallization of cordierite/indialite phases and pore size variability in relation to impurity of kaolins are documented and discussed.

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Zhang, Jin, Zhide Li, Fushun Xu e Chongjun Bao. "Quantification and Modelling of the Multiphase-Coupled Strengthening Effect in Al-Cu-Li Alloy". Metals 9, n. 10 (24 settembre 2019): 1038. http://dx.doi.org/10.3390/met9101038.

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After aging heat treatment, Al-Cu-Li alloy, in general, contains a variety of precipitated phases that jointly influence the age-strengthening effect on the alloy. In this work, a multiphase-coupled strengthening model has been established on the basis of a dislocation bypassing mechanism. The model considered situations with different proportions of two strengthening phases, T1 and θ′, and then obtained the dimension and volume fractions of these two strengthening phases via experiments. The values predicted by the multiphase-coupled strengthening model and the classical strengthening superposition model were compared with the measured results. The multiphase-coupled strengthening model established in this work had better consistency with the measured results. Moreover, the modeling method proposed in the paper can also be extended to the system having over two primary strengthening phases. Hence, the model can contribute towards the development of a multi-component precipitation strengthening process for aluminum alloys.

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Sobanska, Anna W., e Jaroslaw Pyzowski. "Quantification of Sunscreen Ethylhexyl Triazone in Topical Skin-Care Products by Normal-Phase TLC/Densitometry". Scientific World Journal 2012 (2012): 1–6. http://dx.doi.org/10.1100/2012/807516.

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Ethylhexyl triazone (ET) was separated from other sunscreens such as avobenzone, octocrylene, octyl methoxycinnamate, and diethylamino hydroxybenzoyl hexyl benzoate and from parabens by normal-phase HPTLC on silica gel 60 as stationary phase. Two mobile phases were particularly effective: (A) cyclohexane-diethyl ether 1 : 1 (v/v) and (B) cyclohexane-diethyl ether-acetone 15 : 1 : 2 (v/v/v) since apart from ET analysis they facilitated separation and quantification of other sunscreens present in the formulations. Densitometric scanning was performed at 300 nm. Calibration curves for ET were nonlinear (second-degree polynomials), withR> 0.998. For both mobile phases limits of detection (LOD) were 0.03 and limits of quantification (LOQ) 0.1 μg spot−1. Both methods were validated.

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Bezerra, U. T., A. E. Martinelli, D. M. A. Melo, M. A. F. Melo e F. M. Lima. "A correlation between Bogue's equations and Taylor's procedure for the evaluation of crystalline phases in special class Portland oilwell cement clinker". Cerâmica 57, n. 341 (marzo 2011): 122–28. http://dx.doi.org/10.1590/s0366-69132011000100016.

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The crystalline composition of Portland cement clinker is commonly established by Bogue's equations, which are based on a series of assumptions that seldom apply to oilwell cements. This is probably due to the presence of additional oxides and phase reconversion upon cooling of the clinker from the calcination temperature. Important differences are therefore observed between the numerical values yielded by the mathematical equations and image analysis quantification. In this study, the concentration of crystalline phases in oilwell cement was determined using Taylor's procedure, which consists in a system of linear equations corresponding to each one of the four main clinker phases. The results revealed an adequate relationship between this method and phase quantification by optical micrography, especially concerning the contents of aluminate and ferrite.

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Riello, P., M. Munarin, S. Silvestrini, E. Moretti e L. Storaro. "X-ray powder diffraction quantitative analysis of an amorphous SiO2–poly(methyl methacrylate) nanocomposite". Journal of Applied Crystallography 41, n. 6 (11 ottobre 2008): 985–90. http://dx.doi.org/10.1107/s0021889808029944.

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Quantification of individual phases within a multiphase amorphous material has been achieved using a newly developed technique based on X-ray powder diffraction. The quantification method was developed during a study of an amorphous silica–poly(methyl methacrylate) (SiO2–PMMA) hybrid nanocomposite. The efficiency of the method as a quantifying tool for individual phases was demonstrated for samples of SiO2–PMMA prepared either by polymerization of methyl methacrylate in the presence of amorphous SiO2or by mechanically mixing known quantities of the individual and pre-prepared SiO2and PMMA materials. The weight percentages of amorphous SiO2in the nanocomposites as determined by application of the new technique were analogously found to be 29%, a result that was supported by thermogravimetric analysis and helium picnometry measurements.

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Gruskovnjak, Astrid, Barbara Lothenbach, Frank Winnefeld, Beat Münch, Renato Figi, Suz-Chung Ko, Michael Adler e Urs Mäder. "Quantification of hydration phases in supersulfated cements: review and new approaches". Advances in Cement Research 23, n. 6 (dicembre 2011): 265–75. http://dx.doi.org/10.1680/adcr.2011.23.6.265.

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Reuther, H., T. Arnold e E. Krawczyk-Bärsch. "Quantification of Secondary Fe-Phases Formed During Sorption Experiments on Chlorites". Hyperfine Interactions 156/157, n. 1-4 (2004): 439–43. http://dx.doi.org/10.1023/b:hype.0000043265.97905.8d.

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Bach, David, Reinhard Schneider e Dagmar Gerthsen. "EELS of Niobium and Stoichiometric Niobium-Oxide Phases—Part II: Quantification". Microscopy and Microanalysis 15, n. 6 (26 ottobre 2009): 524–38. http://dx.doi.org/10.1017/s1431927609991061.

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AbstractA comprehensive electron energy-loss spectroscopy (EELS) study of niobium (Nb) and stable Nb-oxide phases (NbO, NbO2, Nb2O5) was carried out. Part II of this work is devoted to quantitative EELS by means of experimental k-factors derived from the intensity ratio of the O-K edge and the Nb-M4,5 or Nb-M2,3 edges for all three stable Nb-oxides. The precision and accuracy of the quantification are investigated with respect to the influence of intensity-measurement energy windows, background subtraction, and sample thickness. Integration-window widths allowing optimum accuracy are determined. Owing to background-subtraction errors, the Nb-M4,5 edges rather than Nb-M2,3 are preferred for quantification. Different approaches are applied to improve the precision with regard to thickness-related errors. Thus, a precision up to ±1.5% is achieved by averaging spectra from all three reference oxides to determine a k-factor using Nb-M4,5. Using the experimental k-factor, the determination of atomic concentration ratios CNb/CO in the range of 0.4 (Nb2O5) to 1 (NbO) was found to be possible with an accuracy of 0.6% (relative deviation between measured and nominal composition), whereas ratios of calculated partial ionization cross sections lead to less accurate results.

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Shah, Birju, Vasu Kumar Kakumanu e Arvind K. Bansal. "Analytical techniques for quantification of amorphous/crystalline phases in pharmaceutical solids". Journal of Pharmaceutical Sciences 95, n. 8 (agosto 2006): 1641–65. http://dx.doi.org/10.1002/jps.20644.

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Reddy, K. Chiranjeevi, e Kolluru V. L. Subramaniam. "Quantitative phase analysis of slag hydrating in an alkaline environment". Journal of Applied Crystallography 53, n. 2 (13 marzo 2020): 424–34. http://dx.doi.org/10.1107/s1600576720001399.

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An X-ray diffraction (XRD)-based evaluation of the crystalline and amorphous phases in slag hydrating in an alkaline environment is presented. A method is developed for the quantification of the amorphous phases present in hydrating slag in a sodium hydroxide solution. In hydrating slag, the amorphous reaction product is identified as calcium aluminosilicate hydrate. A water-soluble sodium-based amorphous reaction product is also produced. The XRD-based quantification method relies on the direct decomposition of the XRD intensity pattern of the total amorphous phase present in partially hydrated slag into the intensity patterns of the amorphous unreacted slag, the hydrate and the sodium-based product. The unreacted slag content in partially hydrated slag is also determined from the decomposition of the intensity signature of the total amorphous phase. An independent verification of the amorphous unreacted slag content in hydrating slag is obtained from measurements of blends of unhydrated and partially hydrated slag. The XRD-based phase-quantification procedure developed here provides a basis for evaluating the extent of reaction in hydrating slag.

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Kato, Masanao, Sinzo Fujii, Takuji Ui e Eiichi Asada. "Identification and Quantification of Unknown Component Phases in Powder Samples by X-Ray Diffractometry". Powder Diffraction 5, n. 1 (marzo 1990): 33–35. http://dx.doi.org/10.1017/s0885715600015189.

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AbstractA method of analysis for X-ray diffractometry is proposed for determining the number and the concentrations of phases in a series of samples of the same multiphase system. This method can be used when n samples containing N phases, where N<n, with different concentrations are given or prepared from a given sample.The method of principal component analysis was applied to the determination of the number of individual phases in multiphase mixtures. A quantification method using the intensity ratio to an arbitrary chosen standard mixture, which is also one of the mixtures to be analyzed, is proposed.In this study, we examined the validity of this method for X-ray diffractograms of two and three component systems. It is shown that the values determined by the present method are in good agreement with the prepared concentrations of the samples.

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Repnik, Eva, Urška Puh, Nika Goljar, Marko Munih e Matjaž Mihelj. "Using Inertial Measurement Units and Electromyography to Quantify Movement during Action Research Arm Test Execution". Sensors 18, n. 9 (22 agosto 2018): 2767. http://dx.doi.org/10.3390/s18092767.

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In patients after stroke, ability of the upper limb is commonly assessed with standardised clinical tests that provide a complete upper limb assessment. This paper presents quantification of upper limb movement during the execution of Action research arm test (ARAT) using a wearable system of inertial measurement units (IMU) for kinematic quantification and electromyography (EMG) sensors for muscle activity analysis. The test was executed with each arm by a group of healthy subjects and a group of patients after stroke allocated into subgroups based on their clinical scores. Tasks were segmented into movement and manipulation phases. Each movement phase was quantified with a set of five parameters: movement time, movement smoothness, hand trajectory similarity, trunk stability, and muscle activity for grasping. Parameters vary between subject groups, between tasks, and between task phases. Statistically significant differences were observed between patient groups that obtained different clinical scores, between healthy subjects and patients, and between the unaffected and the affected arm unless the affected arm shows normal performance. Movement quantification enables differentiation between different subject groups within movement phases as well as for the complete task. Spearman’s rank correlation coefficient shows strong correlations between patient’s ARAT scores and movement time as well as movement smoothness. Weak to moderate correlations were observed for parameters that describe hand trajectory similarity and trunk stability. Muscle activity correlates well with grasping activity and the level of grasping force in all groups.

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Butler, M. A., e D. J. Dyson. "The Quantification of Different Forms of Cristobalite in Devitrified Alumino-Silicate Ceramic Fibres". Journal of Applied Crystallography 30, n. 4 (1 agosto 1997): 467–75. http://dx.doi.org/10.1107/s0021889897001672.

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When heat treated, amorphous alumino-silicate fibres will devitrify into crystalline phases which on cooling become stable at room temperature. X-ray diffraction has been used to identify and quantify the phases present in such products; mullite and two distinct forms of cristobalite have been observed. One form of cristobalite has been identified as α-cristobalite, the second form has been designated as α′-cristobalite. An internal standard approach was used to enable calibration curves to be obtained for the three crystallite phases, including the α′- cristobalite for which no commercially available standard exists. The accuracy of the methods was estimated as ± 5 wt% for all three crystalline phases present. This was achieved by quantifying the proportion of α′-cristobalite in a standard alumino-silicate fibre after heat treatment for 48 h at 1773 K and then using this material as the `standard' for α′-cristobalite. This `standard' contained 32.9 wt% α′-cristobalite, 1.6 wt% α-cristobalite and 65.5 wt% mullite. The exact nature of the α′- cristobalite phase has also been examined using high-temperature X-ray diffraction and differential scanning calorimetry. It has been shown to be more similar in nature to α-cristobalite than β-cristobalite since it undergoes an α′ → β phase transition on heating. Compared with α-cristobalite it has a different lattice size, and both the temperature and enthalpy of the α′ → β phase transition are lower than for the α → β phase transition. It has been proposed that the α′-cristobalite observed is a defect form of α-cristobalite but with a constant amount of defects/substituted cations which gives it a well defined and consistent structure.

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Cai, Xiaomei, Tingping Lei, Daoheng Sun e Liwei Lin. "A critical analysis of the α, β and γ phases in poly(vinylidene fluoride) using FTIR". RSC Advances 7, n. 25 (2017): 15382–89. http://dx.doi.org/10.1039/c7ra01267e.

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A universal but simple procedure for identifying the α, β and γ phases in PVDF using FTIR is proposed and validated. An integrated quantification methodology for individual β and γ phase in mixed systems is also proposed.

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Ahmad, Naveed, Khadim Hussain e Shahzad Naseem. "Quantification of Phases in Lahore (Pakistan) Airborne Particulates by Matrix-Flushing Method". Journal of Minerals and Materials Characterization and Engineering 01, n. 04 (2013): 168–83. http://dx.doi.org/10.4236/jmmce.2013.14028.

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Hurst, Vernon J., Paul A. Schroeder e Robert W. Styron. "Accurate quantification of quartz and other phases by powder X-ray diffractometry". Analytica Chimica Acta 337, n. 3 (gennaio 1997): 233–52. http://dx.doi.org/10.1016/s0003-2670(96)00425-4.

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35

Döbelin, Nicola. "Interlaboratory study on the quantification of calcium phosphate phases by Rietveld refinement". Powder Diffraction 30, n. 3 (11 agosto 2015): 231–41. http://dx.doi.org/10.1017/s088571561500038x.

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An interlaboratory study (ILS, round robin) was conducted to assess the accuracy and precision of the phase quantification of calcium phosphate (CaP) bioceramics by X-ray diffraction (XRD) and Rietveld refinement. For that purpose, a mixture of hydroxyapatite and β-tricalcium phosphate, two CaP phases commonly used in synthetic bone graft substitutes, was prepared and sent to 12 laboratories for XRD analysis. Results from 26 different instruments were received and evaluated statistically according to ASTM E691 – 13. The statistical analysis revealed that the reproducibility standard deviation of phase quantities was approximately two times greater than the repeatability standard deviation, which is obtained by repeating the analysis on a single instrument configuration multiple times. The 95% reproducibility limit for phase quantities was R = ±1.67 wt%. The study also demonstrated that several participants overinterpreted their data in an attempt to refine crystallite sizes of the minor phase.

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Barcelo, F., P. Olier e J. C. Brachet. "Quantification des phases apparues lors de l’élaboration par frittage d’un alliage TïNi". Revue de Métallurgie 90, n. 9 (settembre 1993): 1135. http://dx.doi.org/10.1051/metal/199390091135.

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37

Labidi, Islem, Sonia Boughanmi, Houcine Tiss e Adel Megriche. "Critical research study of quantification methods of mineralogical phases in cementitious materials". Journal of the Australian Ceramic Society 55, n. 4 (14 febbraio 2019): 1127–37. http://dx.doi.org/10.1007/s41779-019-00327-5.

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38

Lopez Galindo, A., J. Torres Ruiz e J. M. Gonzalez Lopez. "Mineral quantification in sepiolite-palygorskite deposits using X-ray diffraction and chemical data". Clay Minerals 31, n. 2 (giugno 1996): 217–24. http://dx.doi.org/10.1180/claymin.1996.031.2.07.

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AbstractA quantification technique useful in analysis of clay-rich deposits containing sepiolite and/or palygorskite has been developed by combining diffractometric and chemical data and represents a considerable improvement on classic quantification based on X-ray diffraction. The required data are: intensity ratios between certain diffraction peaks of calcite-dolomite and sepiolite-palygorskite-smectites, and also the CaO, MgO, K2O, Al2O3 and SiO2 contents. The validity of this method was tested by analysis of artificial mixtures of pure phases of the minerals found in such deposits.

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Jordán, Manuel Miguel, Sergio Meseguer, Francisco Pardo e María Adriana Montero. "High-Temperature Mineral Formation after Firing Clay Materials Associated with Mined Coal in Teruel (Spain)". Applied Sciences 10, n. 9 (29 aprile 2020): 3114. http://dx.doi.org/10.3390/app10093114.

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The production of porcelain stoneware has experienced a considerable increase. Therefore, it was necessary to undertake an investigation that would allow knowing the mineralogical evolution that porcelain stoneware undergoes during the firing process, as well as establishing the influence of the formation of mullite and other mineral or vitreous phases and their quantification. The firing transformations of mine spoils associated with mined coal in the Utrillas-Escucha-Estercuel and Ariño-Andorra areas are studied in this paper. The mineralogical composition of the bulk mine spoils is kaolinite, illite, chlorite, and smectites (in traces), with quartz and feldspar, and minor hematite, calcite, and dolomite. The main objective is to understand the generation of high-temperature mineral phases after firing, and their quantification. The formation of mullite and other high-temperature phases are studied from samples that include variable proportions of illite. Samples with a high content of illite generate mullite at 995 °C. Cristobalite was not detected as a high-temperature phase. Mullite is the most abundant mineral. The hercynite content is higher at low temperatures (995 °C), and hematite content is higher at 1150 °C. The vitreous phase represents about 50% of fired bodies. Despite observing a porous microstructure, the non-porous areas are well sintered.

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Cardoso, Deise de Lima, Diva Anélie de Araújo Guimarães, Pedro Mayor, Maria Auxiliadora Pantoja Ferreira, Leandro Nassar Coutinho e Frederico Ozanan Barros Monteiro. "Follicular Atresia, Cell Proliferation, and Anti-Mullerian Hormone in Two Neotropical Primates (Aotus nancymae and Sapajus macrocephalus)". Animals 13, n. 6 (14 marzo 2023): 1051. http://dx.doi.org/10.3390/ani13061051.

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This study evaluated the follicular atresia, cell proliferation, and anti-Mullerian hormone action in Aotus nancymae and Sapajus macrocephalus during three sexual phases (follicular, luteal, and gestational). Follicular quantification and immunolocalization of Caspase-3 protein, B-cell lymphoma 2 (BCL-2), proliferating cell nuclear antigen (PCNA), and anti-Mullerian hormone (AMH) were performed. A significant difference in the quantification between preantral and antral follicles, with a progressive decrease in the antrals, was identified. Protein and hormonal markers varied significantly between follicle cell types (A. nancymae p = 0.001; S. macrocephalus, p = 0.002). Immunostaining in the preantral and antral follicles was present in all sexual phases; for Caspase-3, in granulosa cells, oocytes, and stroma; for BCL-2, in granulosa cells, oocytes, and theca; and for PCNA and AMH, in oocytes and granulosa cells. The immunostaining for Caspase-3 was more expressive in the preantral follicles (follicular phase, p < 0.05), while that for BCL-2 and PCNA was more expressive in the antral follicles of the follicular phase. The AMH was more expressive in the primary and antral follicles of nonpregnant females, in both the follicular and luteal phases. Our results contribute to understanding the ovarian follicular selection, recruitment, and degeneration of these species.

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Meier, Thomas, Dominique Laniel e Florian Trybel. "Direct hydrogen quantification in high-pressure metal hydrides". Matter and Radiation at Extremes 8, n. 1 (1 gennaio 2023): 018401. http://dx.doi.org/10.1063/5.0119159.

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High-pressure metal hydride (MH) research evolved into a thriving field within condensed matter physics following the realization of metallic compounds showing phonon mediated near room-temperature superconductivity. However, severe limitations in determining the chemical formula of the reaction products, especially with regards to their hydrogen content, impedes a deep understanding of the synthesized phases and can lead to significantly erroneous conclusions. Here, we present a way to directly access the hydrogen content of MH solids synthesized at high pressures in (laser-heated) diamond anvil cells using nuclear magnetic resonance spectroscopy. We show that this method can be used to investigate MH compounds with a wide range of hydrogen content, from MH x with x = 0.15 (CuH0.15) to x ≲ 6.4 (H6±0.4S5).

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42

Mežibrický, Roland, e Mária Fröhlichová. "COMPARISON OF IRON ORE SINTER MINERALOGY QUANTIFICATION, WHEN XRD-PATTERNS FOR SFCA/SFCA-I AND OTHER CALCIUM FERRITES ARE CONSIDERED". Acta Metallurgica Slovaca 23, n. 3 (27 settembre 2017): 283. http://dx.doi.org/10.12776/ams.v23i3.899.

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<p class="AMSmaintext">At present, the powder XRD is widely used analytical method for iron ore sinter mineralogy determination. In many researches, diffraction data for SFCA and SFCA-I phases were not available and diffraction data for other calcium ferrites were used instead. Therefore, the aim of this paper is to bring a comparison between evaluation of diffractograms, when SFCA/SFCA-I, and, other calcium ferrites, respectively, are considered. As a result, the quantification of phases is quite comparable, when minerals are collected into groups, i.e. hematite, magnetite, calcium ferrites, silicates and non-assimilated non-ferrous phases. Only in the case of silicates a comparison tends to be dissatisfactory.</p>

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43

Pérez, Nora A., Lauro Bucio, Xim Bokhimi, Enrique Lima e Enrique Soto. "Quantification of amorphous phases in the silt fraction of Mexican pre-Hispanic adobe earth bricks". Journal of Applied Crystallography 49, n. 2 (18 marzo 2016): 561–68. http://dx.doi.org/10.1107/s1600576716002806.

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This study is focused on quantifying the amorphous phases in soil-related material samples by quantitative phase analysis (QPA) with a carefully designed methodological strategy in the X-ray diffraction sample measurement and in the refinement procedure. The configuration applied was Debye–Scherrer geometry with Mo Kα radiation which, together with meticulous instrumental profile modelling using an LaB6 standard, allowed the refinement of a minimum of sample-related parameters. This method was applied to two micro-samples of adobe earth bricks from The Great Pyramid of Cholula, Mexico, and one local soil micro-sample containing several amorphous and semi-crystalline phases such as allophane, volcanic glass and opal. The results obtained by the QPA method, complemented by elemental particle induced X ray emission (PIXE) spectrometry analysis, were compared with a silicon chemical environment analysis by 29Si MAS-NMR. An average amorphous content of 40 wt% was calculated with the QPA/PIXE results, which is in agreement within 10% with the NMR experiments. Consequently, the methodology proposed could be of interest for further studies of cultural heritage geomaterials, which usually contain amorphous phases in their composition and allow only micro-sampling.

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44

Zhao, Yao, Shuai Wen, Yan Wang, Wenshuo Zhang, Xiangming Xu e Yi Mou. "A Review of Recent Advances in Chromatographic Quantification Methods for Cyanogenic Glycosides". Molecules 29, n. 20 (11 ottobre 2024): 4801. http://dx.doi.org/10.3390/molecules29204801.

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Cyanogenic glycosides are naturally occurring compounds found in numerous plant species, which can release toxic hydrogen cyanide upon hydrolysis. The quantification of cyanogenic glycosides is essential for assessing their potential toxicity and health risks associated with their consumption. Liquid chromatographic techniques coupled with various detectors have been widely used for the quantification of cyanogenic glycosides. In this review, we discuss recent advances in chromatographic quantification methods for cyanogenic glycosides, including the development of new stationary phases, innovative sample preparation methods, and the use of mass spectrometry. We also highlight the combination of chromatographic separation with mass spectrometric detection for the identification and quantification of specific cyanogenic glycosides and their metabolites in complex sample matrices. Lastly, we discuss the current challenges and future perspectives in the development of reliable reference standards, optimization of sample preparation methods, and establishment of robust quality control procedures. This review aims to provide an overview of recent advances in chromatographic quantification methods for cyanogenic glycosides and their applications in various matrices, including food products, biological fluids, and environmental samples.

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45

Blacher, Silvia, Laetitia Devy, Ruslan Hlushchuk, Etienne Larger, Noel Lamandé, Peter Burri, Pierre Corvol, Valentin Djonov, Jean-Michel Foidart e Agnes Noël. "QUANTIFICATION OF ANGIOGENESIS IN THE CHICKEN CHORIOALLANTOIC MEMBRANE (CAM)". Image Analysis & Stereology 23, n. 3 (3 maggio 2011): 169. http://dx.doi.org/10.5566/ias.v24.p169-180.

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The chick chorioallantoic membrane (CAM) provides a suitable in vivo model to study angiogenesis and evaluate several pro- and anti-angiogenic factors and compounds. In the present work, new developments in image analysis are used to quantify CAM angiogenic response from optical microscopic observations, covering all vascular components, from the large supplying and feeding vessels down to the capillary plexus. To validate our methodology angiogenesis is quantified during two phases of CAM development (day 7 and 13) and after treatment with an antiangiogenic modulator of the angiogenesis. Our morphometric analysis emphasizes that an accurate quantification of the CAM vasculature needs to be performed at various scales.

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46

Hall, Caitrín, Ji Chul Kim e Alexandra Paxton. "Multidimensional recurrence quantification analysis of human-metronome phasing". PLOS ONE 18, n. 2 (23 febbraio 2023): e0279987. http://dx.doi.org/10.1371/journal.pone.0279987.

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Perception-action coordination (also known as sensorimotor synchronization, SMS) is often studied by analyzing motor coordination with auditory rhythms. The current study assesses phasing—a compositional technique in which two people tap the same rhythm at varying phases by adjusting tempi—to explore how SMS is impacted by individual and situational factors. After practice trials, participants engaged in the experimental phasing task with a metronome at tempi ranging from 80–140 beats per minute (bpm). Multidimensional recurrence quantification analysis (MdRQA) was used to compare nonlinear dynamics of phasing performance. Varying coupling patterns emerged and were significantly predicted by tempo and linguistic experience. Participants who successfully phased replicated findings from an original case study, demonstrating stable tapping patterns near in-phase and antiphase, while those unsuccessful at phasing showed weaker attraction to in-phase and antiphase.

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47

Bogale, Melaku A., Huiying Yu, Thompson Sarkodie-Gyan e Amr Abdelgawad. "Characterization and quantification of gait deficits within gait phases using fuzzy-granular computing". Journal of Biomedical Science and Engineering 05, n. 12 (2012): 720–28. http://dx.doi.org/10.4236/jbise.2012.512090.

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48

Signes-Frehel, M., P. Maes e C. Haehnel. "Etude des phases d'un clinker par diffractométrie des rayons X : vers la quantification". Le Journal de Physique IV 06, n. C4 (luglio 1996): C4–135—C4–142. http://dx.doi.org/10.1051/jp4:1996414.

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49

Skibsted, J�rgen, Hans J. Jakobsen e Christopher Hall. "Quantification of calcium silicate phases in Portland cements by 29Si MAS NMR spectroscopy". Journal of the Chemical Society, Faraday Transactions 91, n. 24 (1995): 4423. http://dx.doi.org/10.1039/ft9959104423.

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50

Duché, Daniel, Van Luu-The, Corinne Ferraris, Jacques Leclaire e Fernand Labrie. "Quantification of phases 1 and 2 metabolism enzymes in Episkin™ and epidermis". Toxicology Letters 180 (ottobre 2008): S121. http://dx.doi.org/10.1016/j.toxlet.2008.06.377.

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