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| Registros recuperados: 11 | |
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| Andrews, John T.; Kristjansdottir, Greta B.; Eberl, Dennis D.; Jennings, Anne E.. |
| This paper re-evaluates how well quantitative x-ray diffraction (qXRD) can be used as an exploratory method of the weight percentage (wt%) of volcaniclastic sediment, and to identify tephra events in marine cores. In the widely used RockJock v6 software programme, qXRD tephra and glass standards include the rhyodacite White River tephra (Alaska), a rhyolitic tephra (Hekla-4) and the basaltic Saksunarvatn tephra. Experiments of adding known wt% of tephra to felsic bedrock samples indicated that additions >= 10 wt% are accurately detected, but reliable estimates of lesser amounts are masked by amorphous material produced by milling. Volcaniclastic inputs range between 20 and 50 wt%. Primary tephra events are identified as peaks in residual qXRD glass wt%... |
| Tipo: Text |
Palavras-chave: X-ray diffraction; Tephras; Iceland Holocene. |
| Ano: 2013 |
URL: https://archimer.ifremer.fr/doc/00265/37578/36528.pdf |
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| Testoni,Samara Alves; Almeida,Jaime Antonio de; Silva,Luana da; Andrade,Gabriel Ramatis Pugliese. |
| ABSTRACT Shrinkage capacity (caráter retrátil in Portuguese) is a new diagnostic characteristic recently introduced in the Brazilian System of Soil Classification (SiBCS) to indicate shrink and swell properties observed in subtropical soils from highland plateaus in southern Brazil, specifically in Oxisols with brown colors. In soils located in road cuts exposed to drying for some weeks, strong shrinkage of soil volume is observed in these soils, resulting in the formation of pronounced vertical cracks and large and very large prismatic structures, which crumble in blocks when handled. We hypothesize that such properties are related to their clay mineralogy, although there are no conclusive studies about this, the motive for the present study. Samples of... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Kaolinite-smectite; Interstratified clay mineral; X-ray diffraction; Quasicrystals. |
| Ano: 2017 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-06832017000100420 |
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| Simões,Ilka Sumiyoshi; Gioielli,Luiz Antonio. |
| The objective of this study was to verify the influence of temperature on crystallization of binary and ternary mixtures of two hydrogenated fats and soybean oil, by polarized light microscopy at temperatures of 30° C, 35° C, and 40° C. The types of crystals observed were spherulites type A, and B and the polymorphic forms were ß , and ß -prime. The soybean oil does not contribute statistically to total area or maximum diameter of the crystals. At 35° C the positive relative coefficients to the interactions presented, in general, absolute values higher than the negative ones, pointing that the crystals were larger than what could be expected, if there was no interaction among the components. At 40° C the negative relative coefficients revealed, in general,... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Crystal morphology; Hydrogenated fat; Mixture; X-ray diffraction. |
| Ano: 2000 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-89132000000200015 |
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| Solís Martínez, Martín. |
| Se evaluó el efecto de la adición de azufre y fósforo sobre la extractabilidad de Pb, Cd y Ni, y en la biodisponibilidad para maíz y alfalfa en el valle del Mezquital, Hidalgo. Se muestrearon los suelos de 13 sitios, se caracterizaron física y químicamente y se determinaron los elementos potencialmente tóxicos totales y extractables. De estos suelos se seleccionaron tres (Atitalaquia, Tlahuelilpan y Tepatepec) para establecer experimentos de equilibrio en el laboratorio. Los suelos se incubaron con dosis crecientes de azufre (0, 2, 4 y 6 t ha-1) y fósforo (0, 250, 500, 1000 y 2000 mg L-1), durante cinco y dos semanas, respectivamente. Se cuantificó la concentración de Pb, Cd y Ni, unidos a las diferentes fracciones del suelo (soluble, FI; intercambiable,... |
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Palavras-chave: Elementos potencialmente tóxicos; Extracción secuencial; Alfalfa; Maíz; Difracción de rayos x; Potentially toxic elements; Sequential extraction; Corn; X-ray diffraction; Edafología; Doctorado. |
| Ano: 2014 |
URL: http://hdl.handle.net/10521/2268 |
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| Nouet, Julius; Bassinot, Franck. |
| Several authors suggested that the thinning, with increasing depth of deposition, of calcite X-ray diffractometry (XRD) peaks obtained on planktonic foraminifera tests resulted from the preferential removal of their poorly crystallized parts as dissolution increases. By deconvolving XRD peak (104) from Globorotalia tumida (surface sediments, Sierra Leone Rise depth transect), we show that the full width at midheight does not depend only upon crystallinity, but reflects also the chemical and structural heterogeneity of foraminifera tests, which results in closely spaced, individual (104) diffraction peaks corresponding to phases with slightly different Mg contents. G. tumida contains two calcite phases: a well crystallized, Mg-poor calcite and a poorly... |
| Tipo: Text |
Palavras-chave: Dissolution; Foraminifera; X-ray diffraction; Crystallinity; Deconvolution. |
| Ano: 2007 |
URL: https://archimer.ifremer.fr/doc/00235/34626/32973.pdf |
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| Moterle,Diovane Freire; Bortoluzzi,Edson Campanhola; Kaminski,João; Rheinheimer,Danilo dos Santos; Caner,Laurent. |
| ABSTRACT Ferralsols ( Latossolos ) should contain few or no 2:1 clay minerals and have low potassium (K) contents, and consequently low levels of non-exchangeable K forms are expected. The aim of this study was to evaluate how the clay mineralogy of a Ferralsol affects the soil K dynamics in response to K fertilization during cropping and whether the clay mineralogy was altered due to successive crops and K fertilization. A tropical Brazilian Ferralsol under field conditions was sampled (0.00-0.20 m) in contrasting K fertilization plots: no K application (control plot) and 3,200 kg ha-1 applied K2O fertilizer. These two treatments were submitted at eight different crop cycles, performed in pots under greenhouse conditions, and fertilized with 0, 30, and 90... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Potassium forms; K fertilization; Non-exchangeable K; 2:1 clay minerals; X-ray diffraction. |
| Ano: 2019 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-06832019000100512 |
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| Chaves,Lucia Helena Garófalo; Curry,Joan Elizabeth; Stone,David Andrew; Chorover,Jon. |
| In order to investigate the efficiency of sulfate green rust (GR2) to remove Ni from solution, GR2 samples were synthesized under controlled laboratory conditions. Some GR2 samples were synthesized from Fe(II) and Fe(III) sulfate salts by precipitation. Other samples were prepared by coprecipitation, of Ni(II), Fe(II) and Fe(III) sulfate salts, i.e., in the presence of Ni. In another sample, Ni(II) sulfate salt was added to pre-formed GR2. After an initial X-ray diffraction (XRD) characterization all samples were exposed to ambient air in order to understand the role of Ni in the transformation of the GR2 samples. XRD was repeated after 45 days. The results showed that Nious GR2 prepared by coprecipitation is isomorphous to Ni-free GR2, i.e. Ni is... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Nickel incorporation; Nickel adsorption; X-ray diffraction; Isomorphous substitution. |
| Ano: 2007 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-06832007000400021 |
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| Brinatti,André Maurício; Mascarenhas,Yvonne Primerano; Pereira,Vitor Paulo; Partiti,Carmen Silvia de Moya; Macedo,Álvaro. |
| The mineralogical characterization through mineral quantification of Brazilian soils by X-ray diffraction data using the Rietveld Method is not common. A mineralogical quantification of an Acric Ferralsol from the Ponta Grossa region, state of Paraná, Brazil, was carried out using this Method with X-Ray Diffraction data to verify if this method was suitable for mineral quantification of a highly-weathered soil. The A, AB and B3 horizons were fractioned to separate the different particle sizes: clay, silt, fine sand (by Stokes Law) and coarse sand fractions (by sieving), with the procedure free of chemical treatments. X-ray Fluorescence, Inductively Coupled Plasma Atomic Emission Spectrometry, Infrared Spectroscopy and Mössbauer Spectroscopy were used in... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Acric Ferralsol; Clay fraction; Silt fraction; Mineralogical quantification; X-ray diffraction. |
| Ano: 2010 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-90162010000400013 |
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| Souza,Camila Prado Cenciani de; Abreu,Cleide Aparecida de; Cunha,José Francisco da; Costa,Geraldo Magela da; Andrade,Cristiano Alberto de. |
| Alternative copper (Cu) sources could be used in fertilizer production, although the bioavailability of copper in these materials is unknown. The objective of this study was to evaluate the extractants neutral ammonium citrate (NAC), 2 % citric acid, 1 % acetic acid, 10 % HCl, 10 % H2SO4, buffer solution pH 6.0, DTPA, EDTA, water, and hot water in the quantification of available Cu content in several sources, relating them to the relative agronomic efficiency (RAE) of wheat grown in a clayey Latossolo Vermelho eutrófico (Oxisol) and Neossolo Quartzarênico (Typic Quartzipsamment). Copper was applied at the rate of 1.5 mg kg-1 as scrap slag, brass slag, Cu ore, granulated copper, and copper sulfate. The extractants 10 % HCl, 10 % H2SO4, and NAC extracted... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Extractants; Industrial waste; Micronutrients; Triticum aestivum; X-ray diffraction. |
| Ano: 2015 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-06832015000200553 |
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| Registros recuperados: 11 | |
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