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Element Contents (element + content)
Kinds of Element Contents Selected AbstractsChemistry and Morphology of Hydrogarnets Formed in Cement-Based CASH Hydroceramics Cured at 200° to 350°CJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 5 2009Konstantinos Kyritsis We have studied the chemistry and the morphology of hydrogarnet crystals produced in cement-based hydroceramic materials at elevated temperatures (200°,350°C) with silica and alumina additions. Such materials lie within the hydrothermal CaO,Al2O3,SiO2,H2O (CASH) system. Hydrogarnet Ca3Al2(SiO4)3,y(OH)4y is the dominant aluminum bearing phase formed and its composition is influenced mainly by the curing temperature and to a lesser degree by the addition of silica. The composition parameter y was estimated by Rietveld refinement of X-ray diffraction (XRD) data. Electron probe microanalysis (EPMA) shows that the hydrogarnets incorporate minor elements such as Fe, Mg, and S. EPMA data confirmed the hydrogarnet composition estimated from XRD. Both octahedral and icositetrahedral forms are observed. The icositetrahedral form is associated with higher minor element content. [source] Differentiation of eight tea (Camellia sinensis) cultivars in China by elemental fingerprint of their leavesJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 14 2009Yingxu Chen Abstract BACKGROUND: Tea is an infusion made from dried leaves of tea (Camellia sinensis) and can be a good dietary source of essential trace metals for humans. Therefore, it is necessary to consider variations in element content of tea leaves among tea cultivars. Thus, elemental fingerprint techniques, based on elemental contents (Al, B, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Na, P, Pb, and Zn) determined by inductively coupled plasma atomic emission spectrometry (ICP-AES) and multivariate statistical analysis, have been used to differentiate eight tea cultivars. RESULTS: The ranges of element concentrations in leaves of the eight cultivars were in good agreement with those obtained in previous studies and the level of most elements in tea leaves was significantly different among cultivars. The classifications of eight tea cultivars were 100% accurate in total by principal component analysis (PCA), hierarchical cluster analysis (HCA), linear discriminant analysis (LDA), and back-propagation neural network (BPNN) analysis. CONCLUSION: Each cultivar presented a distinctive element fingerprint and the elements in tea leaves can be significant predictors in differentiating tea cultivars. Copyright © 2009 Society of Chemical Industry [source] An ethnoarchaeological study of chemical residues in the floors and soils of Q'eqchi' Maya houses at Las Pozas, GuatemalaGEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL, Issue 6 2002Fabián G. Fernández This ethnoarchaeological study at the Q'eqchi' Maya village of Las Pozas, Guatemala, aimed to refine the understanding of the relationship between soil chemical signatures and human activities for archaeological applications. The research involved phosphorus, exchangeable ion (calcium, potassium, magnesium, sodium), and trace element analysis of soils and earth floors extracted by Mehlich II, ammonium acetate, and DTPA chelate solutions, respectively. The results showed high levels of phosphorus, potassium, magnesium, and pH in food preparation areas, as well as high phosphorus concentrations and low pH in food consumption areas. The traffic areas exhibited low phosphorus and trace element contents, whereas refuse disposal areas were enriched. These results provide important information for the understanding of space use in ancient settlements. © 2002 Wiley Periodicals, Inc. [source] Reference Minerals for the Microanalysis of Light ElementsGEOSTANDARDS & GEOANALYTICAL RESEARCH, Issue 2-3 2001M. Darby Dyar tourmaline; danburite; spodumène; muscovite; isotopes The quantitative determination of light element concentrations in geological specimens represents a major analytical challenge as the electron probe is generally not suited to this task. With the development of new in situ analytical techniques, and in particular the increasing use of secondary ion mass spectrometry, the routine determination of Li, Be and B contents has become a realistic goal. However, a major obstacle to the development of this research field is the critical dependence of SIMS on the availability of well characterized, homogeneous reference materials that are closely matched in matrix (composition and structure) to the sample being studied. Here we report the first results from a suite of large, gem crystals which cover a broad spectrum of minerals in which light elements are major constituents. We have characterized these materials using both in situ and wet chemical techniques. The samples described here are intended for distribution to geochemical laboratories active in the study of light elements. Further work is needed before reference values for these materials can be finalized, but the availability of this suite of materials represents a major step toward the routine analysis of the light element contents of geological specimens. La détermination quantitative des concentrations en éléments légers dans les échantillons géologiques représente un défi analytique majeur, la sonde électronique ne convenant généralement pas pour ce travail. Avec le développement de nouvelles techniques analytiques in situ, en particulier l'utilisation grandissante de la spectrométrie ionique secondaire, la détermination en routine des teneurs en Li, Be et B est devenue un objectif réaliste. Toutefois, un obstacle majeur dans le développement de cette recherche subsiste : la technique SIMS est dépendante de la disponibilité de matériaux de référence bien caractérisés et homogènes proches en composition et en structure de l'échantillon étudié. Nous rapportons ici les premiers résultats obtenus à partie d'un groupe de grands cristaux de qualité gemme recouvrant un large spectre de minéraux composés essentiellement d'éléments légers. Nous avons caractérisé ces matériaux en utilisant à la fois des techniques in situ et par voie humide. Les échantillons décrits ici vont être distribués dans les laboratoires de géochimie spécialisés dans l'étude des éléments légers. Avant la conclusion des valeurs de référence de ces matériaux, des travaux ultérieurs seront nécessaires, mais la disponibilité de l'ensemble de ces matériaux représente une étape importante vers l'analyse en routine des teneurs en éléments légers d'échantillons géologiques. [source] THE COMPOSITION OF TWO SPANISH PEPPER VARIETIES (FRESNO DE LA VEGA AND BENAVENTE-LOS VALLES) IN DIFFERENT RIPENING STAGESJOURNAL OF FOOD QUALITY, Issue 6 2008ANA BERNARDO ABSTRACT The chemical composition of two traditional varieties of Spanish peppers, "Fresno de la Vega" and "Benavente-Los Valles" harvested in the provinces of León and Zamora, respectively, at different ripening stages (green mature, breaker and red) were evaluated. Herein we report the global composition, mineral and trace element contents, and the most relevant physicochemical parameters of each variety of pepper collected in 2 consecutive years. Both pepper varieties showed a similar chemical composition, except in vitamin C content, which resulted to be about 70% higher in Fresno de la Vega peppers. Red ripe fruits were high in total carbohydrates, fructose, glucose, sucrose, fat (64.5, 29.14, 25.57, 2.94, 1.79/100 g dry weight, respectively) and total soluble solids (6.83°Brix). Ascorbic acid content also increased progressively during ripening, reaching a mean value of 1.81 mg/100 g dry weight for Fresno de la Vega peppers. Potassium was the most abundant of the analyzed elements in the all samples, followed by phosphorus, magnesium, calcium and sodium. The order of the levels of the trace elements was iron > manganese > zinc > copper. PRACTICAL APPLICATIONS This report underscores the potential value of two traditional varieties of Spanish peppers and provides information on their composition during ripening to decide the proper harvesting time, which can be useful in the food industry. [source] Petrography, geochemistry, and alteration of country rocks from the Bosumtwi impact structure, GhanaMETEORITICS & PLANETARY SCIENCE, Issue 4-5 2007Forson KARIKARI The country rocks, mainly meta-graywacke, shale, and phyllite of the Early Proterozoic Birimian Supergroup and some granites of similar age, are characterized by two generations of alteration. A pre-impact hydrothermal alteration, often along shear zones, is characterized by new growth of secondary minerals, such as chlorite, sericite, sulfides, and quartz, or replacement of some primary minerals, such as plagioclase and biotite, by secondary sericite and chlorite. A late, argillic alteration, mostly associated with the suevites, is characterized by alteration of the melt/glass clasts in the groundmass of suevites to phyllosilicates. Suevite, which occurs in restricted locations to the north and to the south-southwest of the crater rim, contains melt fragments, diaplectic quartz glass, ballen quartz, and clasts derived from the full variety of target rocks. No planar deformation features (PDFs) in quartz were found in the country rock samples, and only a few quartz grains in the suevite samples show PDFs, and in rare cases two sets of PDFs. Based on a total alkali element-silica (TAS) plot, the Bosumtwi granites have tonalitic to quartz-dioritic compositions. The Nb versus Y and Ta versus Yb discrimination plots show that these granites are of volcanic-arc tectonic provenance. Provenance studies of the metasedimentary rocks at the Bosumtwi crater have also indicated that the metasediments are volcanic-arc related. Compared to the average siderophile element contents of the upper continental crust, both country rocks and impact breccias of the Bosumtwi structure show elevated siderophile element contents. This, however, does not indicate the presence of an extraterrestrial component in Bosumtwi suevite, because the Birimian country rocks also have elevated siderophile element contents, which is thought to result from regional hydrothermal alteration that is also related to widespread sulfide and gold mineralization. [source] Drill core LB-08A, Bosumtwi impact structure, Ghana: Geochemistry of fallback breccia and basement samples from the central upliftMETEORITICS & PLANETARY SCIENCE, Issue 4-5 2007Ludovic FERRIÈRE Two boreholes were drilled to acquire hard-rock samples of the deep crater moat and from the flank of the central uplift (LB-07A and LB-08A, respectively) during a recent ICDP-sponsored drilling project. Here we present results of major and trace element analysis of 112 samples from drill core LB-08A. This core, which was recovered between 235.6 and 451.33 m depth below lake level, contains polymict lithic breccia intercalated with suevite, which overlies fractured/brecciated metasediment. The basement is dominated by meta-graywacke (from fine-grained to gritty), but also includes some phyllite and slate, as well as suevite dikelets and a few units of a distinct light greenish gray, medium-grained meta-graywacke. Most of the variations of the major and trace element abundances in the different lithologies result from the initial compositional variations of the various target rock types, as well as from aqueous alteration processes, which have undeniably affected the different rocks. Suevite from core LB-08A (fallback suevite) and fallout suevite samples (from outside the northern crater rim) display some differences in major (mainly in MgO, CaO, and Na2O contents) and minor (mainly Cr and Ni) element abundances that could be related to the higher degree of alteration of fallback suevites, but also result from differences in the clast populations of the two suevite populations. For example, granite clasts are present in fallout suevite but not in fallback breccia, and calcite clasts are present in fallback breccia and not in fallout suevite. Chondrite-normalized rare earth element abundance patterns for polymict impact breccia and basement samples are very similar to each other. Siderophile element contents in the impact breccias are not significantly different from those of the metasediments, or compared to target rocks from outside the crater rim. So far, no evidence for a meteoritic component has been detected in polymict impact breccias during this study, in agreement with previous work. [source] Australasian microtektites and associated impact ejecta in the South China Sea and the Middle Pleistocene supereruption of TobaMETEORITICS & PLANETARY SCIENCE, Issue 2 2006Billy P. Glass Unmelted ejecta were found associated with the microtektites at this site and with Australasian microtektites in Core SO95,17957,2 and ODP Hole 1144A from the central and northern part of the South China Sea, respectively. A few opaque, irregular, rounded, partly melted particles containing highly fractured mineral inclusions (generally quartz and some K feldspar) and some partially melted mineral grains, in a glassy matrix were also found in the microtektite layer. The unmelted ejecta at all three sites include abundant white, opaque grains consisting of mixtures of quartz, coesite, and stishovite, and abundant rock fragments which also contain coesite and, rarely, stishovite. This is the first time that shock-metamorphosed rock fragments have been found in the Australasian microtektite layer. The rock fragments have major and trace element contents similar to the Australasian microtektites and tektites, except for higher volatile element contents. Assuming that the Australasian tektites and microtektites were formed from the same target material as the rock fragments, the parent material for the Australasian tektites and microtektites appears to have been a fine-grained sedimentary deposit. Hole 1144A has the highest abundance of microtektites (number/cm2) of any known Australasian microtektite-bearing site and may be closer to the source crater than any previously identified Australasian microtektite-bearing site. A source crater in the vicinity of 22° N and 104° E seems to explain geographic variations in abundance of both the microtektites and the unmelted ejecta the best; however, a region extending NW into southern China and SE into the Gulf of Tonkin explains the geographic variation in abundance of microtektites and unmelted ejecta almost as well. The size of the source crater is estimated to be 43 ± 9 km based on estimated thickness of the ejecta layer at each site and distance from the proposed source. A volcanic ash layer occurs just above the Australasian microtektite layer, which some authors suggest is from a supereruption of the Toba caldera complex. We estimate that deposition of the ash occurred ,800 ka ago and that it is spread over an area of at least 3.7 times 107 km2. [source] Chemical variation within fragments of Australasian tektitesMETEORITICS & PLANETARY SCIENCE, Issue 6 2005Trinh Hai SON No data for intra-sample trace element variations existed. Thus, we sectioned a Muong Nong-type tektite fragment from Vietnam and a splash-form tektite fragment from the Philippines into eleven and six pieces, respectively, and analyzed the individual fragments for major and trace element contents. The compositions obtained agree well with those found in previous studies, supporting argument that tektites have been derived from terrestrial upper crustal sediments. Chemical variations within the tektite fragments are present, but do not show any systematic trends, probably reflecting incomplete mixing of parent rocks. The intra-sample heterogeneity of the Muong Nong-type tektite is more pronounced than that in the philippinite. For the Muong Nong-type tektite, the intra-sample variation in the trace element contents is higher than that for the major elements, again reflecting target rock properties. For the philippinite the intra-sample variations mostly do not exceed the limits imposed by the precision of the analytical data, confirming that the splash form tektites are indeed well homogenized. [source] Ibitira: A basaltic achondrite from a distinct parent asteroid and implications for the Dawn missionMETEORITICS & PLANETARY SCIENCE, Issue 5 2005David W. MITTLEFEHLDT The mean Fe/Mn ratio of pyroxenes in Ibitira with <10 mole% wollastonite component is 36.4 ± 0.4; this value is well resolved from those of similar pyroxenes in five basaltic eucrites studied for comparison, which range from 31.2 to 32.2. Data for the latter five eucrites completely overlap. Ibitira pyroxenes have lower Fe/Mg than the basaltic eucrite pyroxenes; thus, the higher Fe/Mn ratio does not reflect a simple difference in oxidation state. Ibitira also has an oxygen isotopic composition, alkali element contents, and a Ti/Hf ratio that distinguish it from basaltic eucrites. These differences support derivation from a distinct parent asteroid. Thus, Ibitira is the first recognized representative of the fifth known asteroidal basaltic crust, the others being the HED, mesosiderite, angrite, and NWA 011 parent asteroids. 4 Vesta is generally assumed to be the HED parent asteroid. The Dawn mission will orbit 4 Vesta and will perform detailed mapping and mineralogical, compositional, and geophysical studies of the asteroid. Ibitira is only subtly different from eucritic basalts. A challenge for the Dawn mission will be to distinguish different basalt types on the surface and to attempt to determine whether 4 Vesta is indeed the HED parent asteroid. [source] Effects of dietary zinc levels on growth, serum zinc, haematological parameters and tissue trace elements of soft-shelled turtles, Pelodiscus sinensisAQUACULTURE NUTRITION, Issue 3 2010S.-C. HUANG Abstract A 10-week feeding trial was conducted to evaluate the effects of dietary zinc (Zn) contents on the growth, tissue trace element contents and serum Zn levels in soft-shelled turtles, Pelodiscus sinensis. Juvenile soft-shelled turtles approximately 4.8 g in body weight were fed casein-based diets containing seven levels of Zn (14, 23, 32, 43, 58, 87 and 100 mg kg,1) for 10 weeks. There were no significant differences (P > 0.05) in weight gain (WG), feed conversion ratio (FCR) or protein efficiency ratio (PER) among the dietary treatments. However, Zn concentrations in the liver, serum and carapace of turtles fed the basal diet containing 14 mg Zn kg,1 were the lowest among all groups. Zn contents in the liver, serum and carapace increased when dietary Zn increased up to a dietary Zn level of approximately 43 mg kg,1. Beyond this dietary level, tissue Zn contents were relatively constant. Carapace iron (Fe), selenium (Se) in hard tissues and haemoglobin concentrations decreased when dietary Zn increased. Dietary Zn requirements of juvenile soft-shelled turtles derived from regression modelling using the liver, serum, carapace and bone Zn contents as indicators were 42, 39, 35 and 46 mg Zn kg,1, respectively. [source] Petrological characterisation of ,alabaster' from the Marib province in Yemen and its use as an ornamental stone in Sabaean cultureARABIAN ARCHAEOLOGY AND EPIGRAPHY, Issue 1 2009Christian Weiss ,Yemen alabaster', a calcareous sinter, is a unique building and ornamental stone of the Sabaean culture (c. 1000 BC to 100 AD). This study characterises the quarries and describes the facies of their stones. Through thin sections, luminescence microscopy and geochemical analyses, ,Yemen alabaster' can be classified and assigned a quarry source. The stone is a calcareous sinter related to volcanism in the Marib province. It can be divided into several microfacies types different in luminescence and trace element contents. During Sabaean times it was mined in highly organised quarries including underground quarries and used extensively in the Sabaean kingdom. [source] | |||||||||||||