The abundances of 60 elements in 616 Ocean Floor Basaltic (OFB) glasses from the Abyssal Volcanic Glass Data File (AVGDF) of the Smithsonian Institution have been determined by laser‐ablation ...(LA)‐ICP‐MS and electron microprobe analysis (EMPA). The elements analyzed include all 28 of the refractory lithophile elements, which provide the framework for establishing the geochemical behavior and source abundances of volatile, chalcophile and siderophile elements. In addition to the traditionally analyzed elements (rare earth elements (REE), high field strength elements (HFSE), large ion lithophile elements (LILE) and first row transition elements (FRTE)), we report analyses for lesser‐analyzed elements (Li, Be, Ga, Ge, As, Se, Mo, Ag, Cd, In, Sn, Sb, W, Tl and Bi). The precision of the method for most elements is between 2 and 4%, one standard deviation, although ratios of elements determined simultaneously are more precise (e.g., REE, Zr/Hf). Subsets of 329 glasses were analyzed by electron microprobe for S and 154 glasses for Cl. The results define a representative trace element geochemistry of OFB, against which local variations resulting from differences in basalt petrogenesis in a range of tectonic settings or different styles of magmatic differentiation may be compared.
Key Points
New data file of analyses of 60 elements in 616 volcanic glass samples
The results define a representative trace element array for OFB
Improvement in the precision of data available for ocean floor basalts
The composition of the fine-grained matrix of glacial diamictites from the Mesoarchean, Paleoproterozoic, Neoproterozoic, and Paleozoic, collected from four modern continents, reflects the secular ...evolution of the average composition of the upper continental crust (UCC). The effects of localized provenance are present in some cases, but distinctive geochemical signatures exist in diamictites of the same age from different localities, suggesting that these are global signatures. Archean UCC, dominated by greenstone basalts and to a lesser extent komatiites, was more mafic, based on major elements and transition metal trace elements. Temporal changes in oxygen isotope ratios, rare earth elements, and high field strength elements indicate that the UCC became more differentiated and that tonalite–trondhjemite–granodiorite suites became less important with time, findings consistent with previous studies. We also document the concentrations of siderophile and chalcophile elements (Ga, Ge, Cd, In, Sn, Sb, W, Tl, Bi) and lithophile Be in the UCC through time, and use the data for the younger diamictites to construct a new estimate of average UCC along with associated uncertainties.
Trace elements produce double-edged effects on the lives of animals and particularly of humans. On one hand, these elements represent potentially toxic agents; on the other hand, they are essentially ...needed to support growth and development and confer protection against disease. Certain trace elements and metals are particularly involved in humoral and cellular immune responses, playing the roles of cofactors for essential enzymes and antioxidant molecules. The amount taken up and the accumulation in human tissues decisively control whether the exerted effects are toxic or beneficial. For these reasons, there is an urgent need to re-consider, harmonize and update current legislative regulations regarding the concentrations of trace elements in food and in drinking water. This review aims to provide information on the interrelation of certain trace elements with risk of autoimmune disease, with a particular focus on type 1 diabetes and multiple sclerosis. In addition, an overview of the current regulations and regulatory gaps is provided in order to highlight the importance of this issue for everyday nutrition and human health.
To calculate the distribution of the magnetic field and eddy current density on the surface of an aluminium plate, a method that couples the face-smoothed finite element method (FS-FEM) to the ...boundary element method (BEM) is proposed in this study. This method combines the advantages of the FS-FEM and BEM, which can rapidly and accurately calculate the distributions of vertical magnetic field and eddy current field on the surface of an aluminium plate. The structural parameters and material properties of the coil and aluminium plate are considered. An accurate three-dimensional calculation model is established. Then, the vertical magnetic field and eddy current field distributions are calculated in this study. In the case of the same grid density, compared with the finite element–boundary element coupling algorithm, the simulation results show that the FS-FEM and the boundary element coupling method have obvious advantage in improving the calculation accuracy. The maximum relative error between the calculated results and measured results is only 4%. The proposed method in this study is available for reference to the transient open-domain eddy current field analysis.
As part of a project to investigate the volatilities of so-called "moderately volatile elements" such as Zn, In, Tl, Ga, Ag, Sb, Pb, and Cl during planetary formation, we began by re-calculating the ...condensation temperatures of these elements from a solar gas at 10-4 bar. Our calculations highlighted three areas where currently available estimates of condensation temperature could be improved. One of these is the nature of mixing behavior of many important trace elements when dissolved in major condensates such as silicates, Fe-rich metals, and sulfides. Nonideal solution of the trace elements can alter (generally lower) condensation temperatures by up to 500 K. Second, recent measurements of the halogen contents of CI chondrites (Clay et al. 2017) indicate that the solar system abundance of chlorine is significantly overestimated, and this affects the stabilities of gaseous complexes of many elements of interest. Finally, we have attempted to improve on previous estimates of the free energies of chlorine-bearing solids since the temperature of chlorine condensation has an important control on the condensation temperatures of many trace elements. Our result for the 50% condensation temperature of chlorine, 472 K is nearly 500 K lower than the result of Lodders (2003), and this means that the HCl content of the solar gas at temperatures <900 K is higher than previously estimated. We based our calculations on the program PHEQ (Wood and Hashimoto 1993), which we modified to perform condensation calculations for the elements H, O, C, S, Na, Ca, Mg, Al, Si, Fe, F, Cl, P, N, Ni, and K by free energy minimization. Condensation calculations for minor elements were then performed using the output from PHEQ in conjunction with relevant thermodynamic data. We made explicit provision for nonidealities using information from phase diagrams, heat of solution measurements, partitioning data and by using the lattice strain model for FeS and ionic solids and the Miedema model for solutions in solid Fe. We computed the relative stabilities of gaseous chloride, sulfide, oxide, and hydroxide species of the trace elements of interest and used these, as appropriate in our condensation calculations. In general, our new 50% condensation temperatures are similar to or, because of the modifications noted above, lower than those of Lodders (2003).
This paper presents a simple and effective strain smoothing method (the strain-smoothed element method) for 3-node triangular and 4-node tetrahedral solid finite elements. While piecewise constant ...strain fields are constructed through smoothing domains in previous strain smoothing methods, in the proposed method, linear strain fields are constructed within finite elements using constant strains of neighboring finite elements. When the new strain smoothing method is adopted, the triangular and tetrahedral solid finite elements pass all the basic tests; patch, isotropy and zero energy mode tests, and show improved predictive capability. The formulation of the proposed method is presented in detail. Through various numerical examples, we demonstrate the accuracy improvement achieved.
•We propose a new strain smoothing method for triangular and tetrahedral finite elements.•Linear strain fields are constructed within elements without using special smoothing domains.•The proposed strain-smoothed elements pass patch, isotropic and zero energy mode tests.•Its improved performance is demonstrated through various numerical examples.
The contamination of soil and vegetables with trace elements is one of the most severe ecological problems in developing industrialized countries. Trace elements are released into the environment ...from natural and anthropogenic activities and accumulated in soil and vegetables through various pathways which ultimately affects the human health. The present review aimed at 1) discussing the anthropogenic sources in detail, 2) describing the bioaccumulation, absorption, and transportation of trace elements, 3) exploring the options to reduce the health risk due to consumption of contaminated vegetables, 4) identifying the research and policy gaps related to soil and vegetables contamination with trace elements. Besides these objectives, the present review also detailed the several factors which affect the rate of accumulation, toxicity mechanism, and effects of trace elements on vegetables and humans. Various toxicity indices for health risk assessment have also been described. It is suggested to evaluate the trace metals concentration in irrigation water and soil prior to plant the vegetable to minimize the possible contamination.
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•Leafy vegetables accumulate high concentrations of trace elements.•Bioavailability is highly influenced by soil and plant-related factors.•Consumers of contaminated vegetables are at risk of physiological disorders & cancer.•Safety measures should include metals check at source, medium & point of consumption.
Transposable elements (TEs) are responsible for significant genomic variation in plants. Our understanding of the evolutionary forces shaping TE polymorphism has lagged behind other mutations because ...of the difficulty of accurately identifying TE polymorphism in short-read population genomic data. However, new approaches allow us to quantify TE polymorphisms in population datasets and address fundamental questions about the evolution of these polymorphisms. Here, we discuss how insertional biases shape where, when, and how often TEs insert throughout the genome. Next, we examine mechanisms by which TEs can affect phenotype. Finally, we evaluate current evidence for selection on TE polymorphisms. All together, it is clear that TEs are important, but underappreciated, contributors to intraspecific phenotypic variation, and that understanding the dynamics governing TE polymorphism is crucial for evolutionary biologists interested in the maintenance of variation.
•We do not understand the effects of transposable element (TE) polymorphisms on phenotypic variation.•TE insertional preference is idiosyncratic and varies by species and TE type.•TEs can cause phenotypic variation through multiple mechanisms.•Frequencies of TEs are shaped by selection.
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