Mineralogical and geochemical characterization of weathering profiles developed on mylonites in the Fodjomekwet-Fotouni section of the Cameroon Shear Zone (CSZ), West Cameroon

NASA Astrophysics Data System (ADS)

Tematio, P.; Tchaptchet, W. T.; Nguetnkam, J. P.; Mbog, M. B.; Yongue Fouateu, R.

2017-07-01

The mineralogical and geochemical investigation of mylonitic weathering profiles in Fodjomekwet-Fotouni was done to better trace the occurrence of minerals and chemical elements in this area. Four representative soil profiles were identified in two geomorphological units (upland and lowland) differentiating three weathering products (organo-mineral, mineral and weathered materials). Weathering of these mylonites led to some minerals association such as vermiculite, kaolinite, goethite, smectite, halloysite, phlogopite and gibbsite. The minerals in a decreasing order of abundance are: quartz (24.2%-54.8%); kaolinite (8.4%-36.0%); phlogopite (5.5%-21.9%); goethite (7.8%-16.1%); vermiculite (6.7%-15.7%); smectite (10.2%-11.9%); gibbsite (9.0%-11.8%) and halloysite (5.6%-11.5%) respectively. Patterns of chemical elements allow highlighting three behaviors (enriched elements, depleted elements and elements with complex behavior), depending on the landscape position of the profiles. In the upland weathering products, K, Cr and REEs are enriched; Ca, Mg, Na, Mn, Rb, S and Sr are depleted while Si, Al, Fe, Ti, Ba, Co, Cu, Ga, Mo, Nb, Ni, Pb, Sc, V, Y, Zn and Zr portray a complex behavior. Contrarily, the lowland weathering profiles enriched elements are Fe, Ti, Co, Cr, Cu, V, Zr, Pr, Sm, Tb, Dy, Er and Yb; while depleted elements are Ca, Mg, K, Na, Mn, Ba, Ga, S, Sr, Y, Zn, La, Ce and Nd; and Si, Al, Mo, Nb, Ni, Pb, Rb, Sc evidenced complex behaviors. In all the studied weathering products, the REEs fractionation was also noticeable with a landscape-position dependency, showing light REEs (LREEs) enrichment in the upland areas and heavy REEs (HREEs) in lowland areas. SiO2, Al2O3 and Fe2O3 are positively correlated with most of the traces and REEs (Co, Cu, Nb, Ni, Mo, Pb, Sc, V, Zn, Zr, La, Ce, Sm, Tb, Dy, Er, Yb), pointing to the fact that they may be incorporated into newly formed clay minerals and oxides. Ba, Cr, Ga, Rb, S, Sr, Y, Pr and Nd behave like alkalis and alkaline earths, and are thus highly mobile during weathering.

Geochemical characterization of elements in Vitis vinifera cv. Negroamaro grape berries grown under different soil managements.

PubMed

Pepi, Salvatore; Coletta, Antonio; Crupi, Pasquale; Leis, Marilena; Russo, Sabrina; Sansone, Luigi; Tassinari, Renzo; Chicca, Milvia; Vaccaro, Carmela

2016-04-01

The present geochemical study concerns the impact of viticultural practices in the chemical composition of the grape cultivar "Negroamaro" in Apulia, a southern Italian region renowned for its quality wine. Three types of soil management (SM), two cover cropping with different mixtures, and a soil tillage were considered. For each SM, the vines were irrigated according to two irrigation levels. Chemical composition of soil and of berries of Vitis vinifera cultivar "Negroamaro" were analyzed by X-ray fluorescence, inductively coupled plasma-mass spectrometry and multivariate statistics (linear discrimination analysis). In detail, we investigated major and trace elements behavior in the soil according to irrigation levels, the related index of bioaccumulation (BA) and the relationship between trace element concentration and soil management in "Negroamaro" grapes. The results indicate that soil management affects the mobility of major and trace elements. A specific assimilation of these elements in grapes from vines grown under different soil management was confirmed by BA. Multivariate statistics allowed to associate the vines to the type of soil management. This geochemical characterization of elements could be useful to develop fingerprints of vines of the cultivar "Negroamaro" according to soil management and geographical origin.

Radial elemental and phase separation in Ni-Mn-Ga glass-coated microwires

NASA Astrophysics Data System (ADS)

Shevyrtalov, S.; Zhukov, A.; Medvedeva, S.; Lyatun, I.; Zhukova, V.; Rodionova, V.

2018-05-01

In this manuscript, radial elemental and phase separation in Ni-Mn-Ga glass-coated microwires with high excess Ni as a result of high-temperature annealing was observed. Partial manganese evaporation from the outer part of the metallic nucleus and glass melting results in the formation of manganese oxide at the surface. The lack of manganese due to its evaporation induces Ni3Ga formation in the intermediate part, while in the middle part of the metallic nucleus, the residual L21 phase with an average chemical composition of Ni60Mn9Ga31 remains. The layered structure exhibits soft ferromagnetic behavior below 270 K. The results were discussed taking into account the chemical composition, arising internal stresses, recrystallization, and atomic ordering.

Predicting the ash behavior during biomass combustion in FBC conditions by combining advanced fuel analyses with thermodynamic multicomponent equilibrium calculations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Skrifvars, B.J.; Blomquist, J.P.; Hupa, M.

1998-12-31

Previous work at Aabo Akademi University has focused on identification and quantification of various sintering mechanisms which are relevant for problematic ash behavior during biomass combustion in fluidized bed combustion conditions, and on multi-component multi-phase thermodynamic phase equilibrium calculations of ash chemistry in these conditions. In both areas new information has been developed and useful modeling capabilities have been created. Based on the previous work, the authors now present a novel approach of using a combination of an advanced fuel analysis method and thermodynamic phase equilibrium calculations to predict the chemical and thermal behavior of the ash when firing biomass.more » Four different fuels [coal, forest residues, wood chips, and a mixture of forest residue and wood chips] were analyzed using the chemical fractionation analysis technique. Based on the results from these analyses, the authors formed two different ash fractions, (1) one fine sized fraction consisting of those elements found in the water and weak acid leach, and (2) a coarse ash particle fraction consisting of those elements found in the strong acid leach and non-leachable rest. The small sized ash fraction was then assumed to be carried up with the flue gases and consequently formed the base for any ash related problems in the flue gas channel. This fraction was therefore analyzed on its chemical and thermal behavior using multi-component multi-phase equilibrium calculations, by which the composition and the melting behavior was estimated as a function of the temperature. The amount of melt, which has earlier been found to be strongly related to problematic ash behavior, was finally expressed as a function of the temperature for the fraction. The coarse fraction was treated separately. Here the authors estimate the composition only. The paper discusses the results and their relevance to full scale combustion.« less

Response of explosive HMX to low-velocity impact: modeling by the crystal plasticity finite element method

NASA Astrophysics Data System (ADS)

Ilnitsky, Denis; Inogamov, Nail; Zhakhovsky, Vasily

2017-12-01

Crystal plasticity finite element method (CPFEM) is a powerful tool for modeling the various deformation problems, which takes into account the different plasticity mechanisms at microscale of grain sizes and contribution of anisotropic behavior of each grain to macroscopic deformation pattern. Using this method we simulated deformation and plasticity of high explosive HMX produced by relatively low velocity impact. It was found that such plastic deformations of grains cause local heating which is sufficient to induce chemical reactions.

Assessing the Behavior of Typically Lithophile Elements Under Highly Reducing Conditions Relevant to the Planet Mercury

NASA Technical Reports Server (NTRS)

Rowland, Rick, II; Vander Kaaden, Kathleen E.; McCubbin, Francis M.; Danielson, Lisa R.

2017-01-01

With the data returned from the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) mission, there are now numerous constraints on the physical and chemical properties of Mercury, including its surface composition (e.g., Evans et al. 2012; Nittler et al. 201 l; Peplowski et al. 2012; Weider et al. 2012). The high Sand low FeO contents observed from MESSENGER on the planet's surface suggests a low oxygen fugacity of the present planetary materials. Estimates of the oxygen fugacity for Mercurian magmas are approximately 3- 7 log units below the Iron-Wiistite (Fe-FeO) oxygen buffer (McCubbin et al. 2012; Zolotov et al. 2013), several orders of magnitude more reducing than other terrestrial bodies we have data from such as the Earth, Moon, or Mars (Herd 2008; Sharp, McCubbin, and Shearer 2013; Wadhwa 2008). Most of our understanding of elemental partitioning behavior comes from observations made on terrestrial rocks, but Mercury's oxygen fugacity is far outside the conditions of those samples. With limited oxygen available, lithophile elements may instead exhibit chalcophile, halophile, or siderophile behaviors. Furthermore, very few natural samples of rocks that formed under reducing conditions are available in our collections (e.g., enstatite chondrites, achondrites, aubrites). The goal of this study is to conduct experiments at high pressure and temperature conditions to determine the elemental partitioning behavior of typically lithophile elements as a function of decreasing oxygen fugacity.

The Chemical Behavior of Fluids Released during Deep Subduction Based on Fluid Inclusions

NASA Astrophysics Data System (ADS)

Frezzotti, M. L.; Ferrando, S.

2014-12-01

We present a review of current research on fluid inclusions in (HP-) UHP metamorphic rocks that, combined with existing experimental research and thermodynamic models, allow us to investigate the chemical and physical properties of fluids released during deep subduction, their solvent and element transport capacity, and the subsequent implications for the element recycling in the mantle wedge. An impressive number of fluid inclusion studies indicate three main populations of fluid inclusions in HP and UHP metamorphic rocks: i) aqueous and/or non-polar gaseous fluid inclusions (FI), ii) multiphase solid inclusions (MSI), and iii) melt inclusions (MI). Chemical data from preserved fluid inclusions in rocks match with and implement "model" fluids by experiments and thermodynamics, revealing a continuity behind the extreme variations of physico-chemical properties of subduction-zone fluids. From fore-arc to sub-arc depths, fluids released by progressive devolatilization reactions from slab lithologies change from relatively diluted chloride-bearing aqueous solutions (± N2), mainly influenced by halide ligands, to (alkali) aluminosilicate-rich aqueous fluids, in which polymerization probably governs the solubility and transport of major (e.g., Si and Al) and trace elements (including C). Fluid inclusion data implement the petrological models explaining deep volatile liberation in subduction zones, and their flux into the mantle wedge.

Ca-,Al-rich inclusions in the unique chondrite ALH85085 - Petrology, chemistry, and isotopic compositions

NASA Technical Reports Server (NTRS)

Kimura, Makoto; El-Goresy, Ahmed; Palme, Herbert; Zinner, Ernst

1993-01-01

A comprehensive study is performed for the Ca-,Al-rich inclusions (CAIs) in the unique chondrite ALH85085. The ALH85085 inclusions are smaller (5-80 microns) and more refractory than their counterparts in carbonaceous chondrites. The study includes 42 inclusions for petrography and mineralogy, 15 for bulk major and minor element chemical composition, six for Mg-Al isotopic systematics, 10 for Ca isotopes, nine for Ti isotopes, and six for trace element abundances. In addition, oxygen-isotopic compositions were determined in minerals from a single inclusion. No correlation is found between mineralogy, major element chemistry, and trace element abundances. It is further shown that the high-temperature geochemical behavior of ultrarefractory trace elements is decoupled from that of the major elements Ca and Ti (Ti is correlated with the relatively volatile elements Nb and Yb) implying that perovskite is of only minor importance as carrier of ultrarefractories.

Environmental mineralogy - Understanding element behavior in ecosystems

NASA Astrophysics Data System (ADS)

Brown, Gordon E., Jr.; Calas, Georges

2011-02-01

Environmental Mineralogy has developed over the past decade in response to the recognition that minerals are linked in many important ways with the global ecosystem. Minerals are the main repositories of the chemical elements in Earth's crust and thus are the main sources of elements needed for the development of civilization, contaminant and pollutant elements that impact global and local ecosystems, and elements that are essential plant nutrients. These elements are released from minerals through natural processes, such as chemical weathering, and anthropogenic activities, such as mining and energy production, agriculture and industrial activities, and careless waste disposal. Minerals also play key roles in the biogeochemical cycling of the elements, sequestering elements and releasing them as the primary minerals in crustal rocks undergo various structural and compositional transformations in response to physical, chemical, and biological processes that produce secondary minerals and soils. These processes have resulted in the release of toxic elements such as arsenic in groundwater aquifers, which is having a major impact on the health of millions of people in South and Southeast Asia. The interfaces between mineral surfaces and aqueous solutions are the locations of most chemical reactions that control the composition of the natural environment, including the composition of natural waters. The nuclear fuel cycle, from uranium mining to the disposition of high-level nuclear waste, is also intimately related to minerals. A fundamental understanding of these processes requires molecular-scale information about minerals, their bulk structures and properties such as solubility, their surfaces, and their interactions with aqueous solutions, atmospheric and soil gases, natural organic matter, and biological organisms. Gaining this understanding is further complicated by the presence of natural, incidental, and manufactured nanoparticles in the environment, which are becoming increasingly important due to the rapidly developing field of nanotechnology. As a result of this complexity, Environmental Mineralogy requires the use of the most modern molecular-scale analytical and theoretical methods and overlaps substantially with closely related fields such as Environmental Sciences, low-temperature Geochemistry, and Geomicrobiology. This paper provides brief overviews of the above topics and discusses the complexity of minerals, natural vs. anthropogenic inputs of elements and pollutants into the biosphere, the role of minerals in the biogeochemical cycling of elements, natural nanoparticles, and the Environmental Mineralogy of three major potential pollutant elements (Hg, As and U).

Corrosion-resistant high-entropy alloys: A review

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shi, Yunzhu; Yang, Bin; Liaw, Peter

Corrosion destroys more than three percent of the world’s gross domestic product. Therefore, the design of highly corrosion-resistant materials is urgently needed. By breaking the classical alloy-design philosophy, high-entropy alloys (HEAs) possess unique microstructures, which are solid solutions with random arrangements of multiple elements. The particular locally-disordered chemical environment is expected to lead to unique corrosion-resistant properties. In this review, the studies of the corrosion-resistant HEAs during the last decade are summarized. The corrosion-resistant properties of HEAs in various aqueous environments and the corrosion behavior of HEA coatings are presented. The effects of environments, alloying elements, and processing methods onmore » the corrosion resistance are analyzed in detail. Finally, the possible directions of future work regarding the corrosion behavior of HEAs are suggested.« less

Corrosion-resistant high-entropy alloys: A review

DOE PAGES

Shi, Yunzhu; Yang, Bin; Liaw, Peter

2017-02-05

Corrosion destroys more than three percent of the world’s gross domestic product. Therefore, the design of highly corrosion-resistant materials is urgently needed. By breaking the classical alloy-design philosophy, high-entropy alloys (HEAs) possess unique microstructures, which are solid solutions with random arrangements of multiple elements. The particular locally-disordered chemical environment is expected to lead to unique corrosion-resistant properties. In this review, the studies of the corrosion-resistant HEAs during the last decade are summarized. The corrosion-resistant properties of HEAs in various aqueous environments and the corrosion behavior of HEA coatings are presented. The effects of environments, alloying elements, and processing methods onmore » the corrosion resistance are analyzed in detail. Finally, the possible directions of future work regarding the corrosion behavior of HEAs are suggested.« less

Noble gases and the early history of the Earth: Inappropriate paradigms and assumptions inhibit research and communication

NASA Technical Reports Server (NTRS)

Huss, G. R.; Alexander, E. C., Jr.

1985-01-01

The development of models as tracers of nobel gases through the Earth's evolution is discussed. A new set of paradigms embodying present knowledge was developed. Several important areas for future research are: (1) measurement of the elemental and isotopic compositions of the five noble gases in a large number of terrestrial materials, thus better defining the composition and distribution of terrestrial noble gases; (2) determinations of relative diffusive behavior, chemical behavior, and the distribution between solid and melt of noble gases under mantle conditions are urgently needed; (3) disequilibrium behavior in the nebula needs investigation, and the behavior of plasmas and possible cryotrapping on cold nebular solids are considered.

Nuclear Forensics and Radiochemistry: Chemistry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rundberg, Robert S.

The chemical behavior of radioactive elements can differ from conventional wisdom because the number of atoms can be unusually small. Kinetic effects and unusual oxidation states are phenomena that make radiochemistry different from conventional analytic chemistry. The procedures developed at Los Alamos are designed to minimize these effects and provide reproducible results over a wide range of sample types. The analysis of nuclear debris has the additional complication of chemical fractionation and the incorporation of environmental contaminants. These are dealt with through the use of three component isotope ratios and the use of appropriate end members.

In Situ Trace Element Analysis of an Allende Type B1 CAI: EK-459-5-1

NASA Technical Reports Server (NTRS)

Jeffcoat, C. R.; Kerekgyarto, A.; Lapen, T. J.; Andreasen, R.; Righter, M.; Ross, D. K.

2014-01-01

Variations in refractory major and trace element composition of calcium, aluminum-rich inclusions (CAIs) provide constraints on physical and chemical conditions and processes in the earliest stages of the Solar System. Previous work indicates that CAIs have experienced complex histories involving, in many cases, multiple episodes of condensation, evaporation, and partial melting. We have analyzed major and trace element abundances in two core to rim transects of the melilite mantle as well as interior major phases of a Type B1 CAI (EK-459-5-1) from Allende by electron probe micro-analyzer (EPMA) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) to investigate the behavior of key trace elements with a primary focus on the REEs Tm and Yb.

The importance of trace element speciation in biomedical science.

PubMed

Templeton, Douglas M

2003-04-01

According to IUPAC terminology, trace element speciation reflects differences in chemical composition at multiple levels from nuclear and electronic structure to macromolecular complexation. In the medical sciences, all levels of composition are important in various circumstances, and each can affect the bioavailability, distribution, physiological function, toxicity, diagnostic utility, and therapeutic potential of an element. Here we discuss, with specific examples, three biological principles in the intimate relation between speciation and biological behavior: i) the kinetics of interconversion of species determines distribution within the organism, ii) speciation governs transport across various biological barriers, and iii) speciation can limit potentially undesirable interactions between physiologically essential elements. We will also describe differences in the speciation of iron in states of iron overload, to illustrate how speciation analysis can provide insight into cellular processes in human disease.

Trace element partitioning behavior of coal gangue-fired CFB plant: experimental and equilibrium calculation.

PubMed

Zhang, Yingyi; Nakano, Jinichiro; Liu, Lili; Wang, Xidong; Zhang, Zuotai

2015-10-01

Energy recovery is a promising method for coal gangue utilization, during which the prevention of secondary pollution, especially toxic metal emission, is a significant issue in the development of coal gangue utilization. In the present study, investigation into trace element partitioning behavior from a coal gangue-fired power plant in Shanxi province, China, has been conducted. Besides the experimental analysis, thermodynamic equilibrium calculation was also conducted to help the further understanding on the effect of different parameters. Results showed that Hg, As, Be, and Cd were highly volatile elements in the combustion of coal gangue, which were notably enriched in fly ash and may be emitted into the environment via the gas phase. Cr and Mn were mostly non-volatile and were enriched in the bottom ash. Pb, Co, Zn, Cu, and Ni were semi-volatile elements and were enriched in the fly ash to varying degrees. Equilibrium calculations show that the air/fuel ratio and the presence of Cl highly affect the element volatility. The presence of mineral phases, such as aluminosilicates, depresses the volatility of elements by chemical immobilization and competition in Cl. The coal gangue, fly ash, and bottom ash all passed the toxicity characteristic leaching procedure (TCLP), and their alkalinity buffers the acidity of the solution and contributes to the low solubility of the trace elements.

Effect of silicon on trace element partitioning in iron-bearing metallic melts

NASA Astrophysics Data System (ADS)

Chabot, Nancy L.; Safko, Trevor M.; McDonough, William F.

2010-08-01

Despite the fact that Si is considered a potentially important metalloid in planetary systems, little is known about the effect of Si in metallic melts on trace element partitioning behavior. Previous studies have established the effects of S, C, and P, nonmetals, through solid metal/liquid metal experiments in the corresponding Fe binary systems, but the Fe-Si system is not appropriate for similar experiments because of the high solubility of Si in solid metal. In this work, we present the results from 0.1MPa experiments with two coexisting immiscible metallic liquids in the Fe-S-Si system. By leveraging the extensive available knowledge about the effect of S on trace element partitioning behavior, we explore the effect of Si. Results for 22 trace elements are presented. Strong Si avoidance behavior is demonstrated by As, Au, Ga, Ge, Sb, Sn, and Zn. Iridium, Os, Pt, Re, Ru, and W exhibit weak Si avoidance tendencies. Silicon appears to have no significant effect on the partitioning behaviors of Ag, Co, Cu, Cr, Ni, Pd, and V, all of which had similar partition coefficients over a wide range of Si liquid concentrations from Si-free to 13 wt%. The only elements in our experiments to show evidence of a potentially weak attraction to Si were Mo and Rh. Applications of the newly determined effects of Si to problems in planetary science indicate that (1) The elements Ni, Co, Mo, and W, which are commonly used in planetary differentiation models, are minimally affected by the presence of Si in the metal, especially in comparison to other effects such as from oxygen fugacity. 2) Reduced enstatite-rich meteorites may record a chemical signature due to Si in the metallic melts during partial melting, and if so, elements identified by this study as having strong Si avoidance may offer unique insight into unraveling the history of these meteorites.

Confirmation of the Decay of 283112 and First Indication for Hg-like Behavior of Element 112

NASA Astrophysics Data System (ADS)

Eichler, R.; Aksenov, N. V.; Belozerov, A. V.; Bozhikov, G. A.; Chepigin, V. I.; Dressler, R.; Dmitriev, S. N.; Gäggeler, H. W.; Gorshkov, V. A.; Haenssler, F.; Itkis, M. G.; Lebedev, V. Ya.; Laube, A.; Malyshev, O. N.; Oganessian, Yu. Ts.; Petruschkin, O. V.; Piguet, D.; Rasmussen, P.; Shishkin, S. V.; Shutov, A. V.; Svirikhin, A. I.; Tereshatov, E. E.; Vostokin, G. K.; Wegrzecki, M.; Yeremin, A. V.

2007-05-01

Two gas phase adsorption chemistry experiments aimed at the chemical characterization of element 112 using its isotope 283112 have been performed at the Flerov Laboratory for Nuclear Reactions (FLNR) Dubna, Russia. The applied Insitu-Volatilization and On-line Detection (IVO) technique is a thermochromatographic system combining the determination of the deposition temperature of volatile elements on a surface along a temperature gradient with an efficient detection of the deposited species by event-by-event alpha and SF-fragment spectroscopy. Two possibilities to produce the isotope 283112 were used: 1.) the direct production reaction 238U( 48Ca,3n) 283112; 2.) the reaction 242Pu( 48Ca,3n), where the primary product 287114, decays via alpha emission to 283112 with a half-life of 0.5 s. The chemistry experiments were aimed at a chemical identification of 283112 and an independent confirmation of its decay properties. In the direct reaction no decays related to 283112 were observed. However, two decay chains unambiguously attributed to the decay of 283112 were observed using the second production path. Previously reported observation of 283112 and 279Ds and their decay properties were confirmed. From its thermochromatorgaphic deposition first thermochemical data were deduced for element 112, unveiling it as a typical group 12 element.

Mineral Systems, Their Types, and Distribution in Nature: 2. Products of Contemporary Fumarole Activity at Tolbachik Volcano (Russia) and Vulcano (Italy)

NASA Astrophysics Data System (ADS)

Krivovichev, V. G.; Charykova, M. V.

2017-12-01

The number of mineral species in which a certain chemical element is species-defining (according to statistical data up to 2015) has been specified. Seventy chemical elements are species-defining for 5044 minerals. The following chemical elements lead in the composition of minerals (number of mineral species in parentheses): oxygen (4115), hydrogen (2800), silicon (1471), calcium (1167), sulfur (1056), aluminium (985), sodium (949), iron (945), copper (636), phosphorus (597), arsenic (594), and magnesium (571). The distribution of mineral species by various systems in the products of contemporary fumarole activity at two volcanoes, Tolbachik in Kamchatka, Russia, and Vulcano in Sicily, Italy, has been compared. These locations were also compared for the distribution of species-defining elements. Thus, it has been determined that in fumaroles of both volcanoes, Tl, S, Cl, F and Na are "excessive," present in minerals in elevated amounts, whereas H, Ca, Fe, and Mn are "deficient." The abundance of Cu, Se, V, Mg, Zn, As, and F in minerals at Tolbachik is higher than the global mean values of these elements in the Earth's crust, whereas the abundance is significantly lower at Vulcano. Sn, I, Br, K, Pb, Al, Fe, and Bi demonstrate the opposite behavior. Comparison of the Yadovitaya and Arsenatnaya fumaroles at the Tolbachik volcano showed that the products of the former are richer in H, Cl, Cu, S, K, O, Al, Fe, and Pb, and poorer in As, Ca, Mg, and Na as species-defining elements. In addition, V-and Mo-bearing minerals are found only at Yadovitaya, whereas minerals containing F, Ti, B, Te, and Zn are known only at Arsenatnaya.

Accurate quantitative CF-LIBS analysis of both major and minor elements in alloys via iterative correction of plasma temperature and spectral intensity

NASA Astrophysics Data System (ADS)

Shuxia, ZHAO; Lei, ZHANG; Jiajia, HOU; Yang, ZHAO; Wangbao, YIN; Weiguang, MA; Lei, DONG; Liantuan, XIAO; Suotang, JIA

2018-03-01

The chemical composition of alloys directly determines their mechanical behaviors and application fields. Accurate and rapid analysis of both major and minor elements in alloys plays a key role in metallurgy quality control and material classification processes. A quantitative calibration-free laser-induced breakdown spectroscopy (CF-LIBS) analysis method, which carries out combined correction of plasma temperature and spectral intensity by using a second-order iterative algorithm and two boundary standard samples, is proposed to realize accurate composition measurements. Experimental results show that, compared to conventional CF-LIBS analysis, the relative errors for major elements Cu and Zn and minor element Pb in the copper-lead alloys has been reduced from 12%, 26% and 32% to 1.8%, 2.7% and 13.4%, respectively. The measurement accuracy for all elements has been improved substantially.

Haematic pH sensor for extracorporeal circulation

NASA Astrophysics Data System (ADS)

Ferrari, Luca; Fabbri, Paola; Rovati, Luigi; Pilati, Francesco

2012-03-01

The design and realization of an optical sensor for measuring haematic pH during extracorporeal circulation is presented. It consists of a chemical sensing element in contact with the blood, an interrogation optical head to externally probe the sensing element and the front-end electronics to acquire and process the information of interest. The fluorescein O-methacrylate 97% is used as the indicator. The developed system has been tested in-vitro and on an in-vivo animal model. It showed a linear behavior in the haematic range of interest with a mean error lower than 0.01 units of pH.

A study to investigate the chemical stability of gallium phosphate oxide/gallium arsenide phosphide

NASA Technical Reports Server (NTRS)

Kuhlman, G. J.

1979-01-01

The elemental composition with depth into the oxide films was examined using secondary ion mass spectrometry. Results indicate that the layers are arsenic-deficient through the bulk of the oxide and arsenic-rich near both the oxide surface and the oxide-semiconductor interface region. Phosphorus is incorporated into the oxide in an approximately uniform manner. The MIS capacitor structures exhibited deep-depletion characteristics and hysteresis indicative of electron trapping at the oxide-semiconductor interface. Post-oxidation annealing of the films in argon or nitrogen generally results in slightly increased dielectric leakage currents and decreased C-V hysteresis effects, and is associated with arsenic loss at the oxide surface. The results of bias-temperature stress experiments indicate that the major instability effects are due to changes in the electron trapping behavior. No changes were observed in the elemental profiles following electrical stressing, indicating that the grown films are chemically stable under device operating conditions.

Chemistry of berkelium: A review

NASA Astrophysics Data System (ADS)

Hobart, D. E.; Peterson, J. R.

Element 97 was first produced in December 1949, by the bombardment of americium-241 with accelerated alpha particles. This new element was named berkelium (Bk) after Berkeley, California, the city of its discovery. In the 36 years since the discovery of Bk, a substantial amount of knowledge concerning the physicochemical properties of this relatively scarce transplutonium element was acquired. All of the Bk isotopes of mass numbers 240 and 242 through 251 are presently known, but only berkelium-249 is available in sufficient quantities for bulk chemical studies. About 0.7 gram of this isotope was isolated at the HFIR/TRU Complex in Oak Ridge, Tennessee in the last 18 years. Over the same time period, the scale of experimental work using berkelium-249 has increased from the tracer level to bulk studies at the microgram level to solution and solid state investigations with milligram quantities. Extended knowledge of the physicochemical behavior of berkelium is important in its own right, because Bk is the first member of the second half of the actinide series. In addition, such information should enable more accurate extrapolations to the predicted behavior of heavier elements for which experimental studies are severely limited by lack of material and/or by intense radioactivity.

Modelling the influence of carbon content on material behavior during forging

NASA Astrophysics Data System (ADS)

Korpała, G.; Ullmann, M.; Graf, M.; Wester, H.; Bouguecha, A.; Awiszus, B.; Behrens, B.-A.; Kawalla, R.

2017-10-01

Nowadays the design of single process steps and even of whole process chains is realized by the use of numerical simulation, in particular finite element (FE) based methods. A detailed numerical simulation of hot forging processes requires realistic models, which consider the relevant material-specific parameters to characterize the material behavior, the surface phenomena, the dies as well as models for the machine kinematic. This data exists partial for several materials, but general information on steel groups depending on alloying elements are not available. In order to generate the scientific input data regarding to material modelling, it is necessary to take into account the mathematical functions for deformation behavior as well as recrystallization kinetic, which depends alloying elements, initial microstructure and reheating mode. Besides the material flow characterization, a detailed description of surface changes caused by oxide scale is gaining in importance, as these phenomena affect the material flow and the component quality. Experiments to investigate the influence of only one chemical element on the oxide scale kinetic and the inner structure at high temperatures are still not available. Most data concerning these characteristics is provided for the steel grade C45, so this steel will be used as basis for the tests. In order to identify the effect of the carbon content on the material and oxidation behavior, the steel grades C15 and C60 will be investigated. This paper gives first approaches with regard to the influence of the carbon content on the oxide scale kinetic and the flow stresses combined with the initial microstructure.

Structural flexibility in magnetocaloric RE 5T 4 (RE=rare-earth; T=Si,Ge,Ga) materials: Effect of chemical substitution on structure, bonding and properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Misra, Sumohan

The binary, ternary and multicomponent intermetallic compounds of rare-earth metals (RE) with group 14 elements (Tt) at the RE 5Tt 4 stoichiometry have been known for over 30 years, but only in the past decade have these materials become a gold mine for solid-state chemistry, materials science and condensed matter physics. It all started with the discovery of a giant magnetocaloric effect in Gd 5Si 2Ge 2, along with other extraordinary magnetic properties, such as a colossal magnetostriction and giant magnetoresistance. The distinctiveness of this series is in the remarkable flexibility of the chemical bonding between well-defined, subnanometer-thick slabs andmore » the resultant magnetic, transport, and thermodynamic properties of these materials. This can be controlled by varying either or both RE and Tt elements, including mixed rare-earth elements on the RE sites and different group 14 (or T = group 13 or 15) elements occupying the Tt sites. In addition to chemical means, the interslab interactions are also tunable by temperature, pressure, and magnetic field. Thus, this system provides a splendid 'playground' to investigate the interrelationships among composition, structure, physical properties, and chemical bonding. The work presented in this dissertation involving RE 5T 4 materials has resulted in the successful synthesis, characterization, property measurements, and theoretical analyses of various new intermetallic compounds. The results provide significant insight into the fundamental magnetic and structural behavior of these materials and help us better understand the complex link between a compound's composition, its observed structure, and its properties.« less

Interaction of rare earth elements and components of the Horonobe deep groundwater.

PubMed

Kirishima, Akira; Kuno, Atsushi; Amamiya, Hiroshi; Kubota, Takumi; Kimuro, Shingo; Amano, Yuki; Miyakawa, Kazuya; Iwatsuki, Teruki; Mizuno, Takashi; Sasaki, Takayuki; Sato, Nobuaki

2017-02-01

To better understand the migration behavior of minor actinides in deep groundwater, the interactions between doped rare earth elements (REEs) and components of Horonobe deep groundwater were investigated. Approximately 10 ppb of the REEs, i.e. Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Er, Tm, and Yb were doped into a groundwater sample collected from a packed section in a borehole drilled at 140 m depth in the experiment drift of Horonobe Underground Research Laboratory in Hokkaido, Japan. The groundwater sample was sequentially filtered with a 0.2 μm pore filter, and 10 kDa, 3 kDa and 1 kDa nominal molecular weight limit (NMWL) ultrafilters with conditions kept inert. Next, the filtrate solutions were analyzed with inductively coupled plasma mass spectrometry (ICP-MS) to determine the concentrations of the REEs retained in solution at each filtration step, while the used filters were analyzed through neutron activation analysis (NAA) and TOF-SIMS element mapping to determine the amounts and chemical species of the trapped fractions of REEs on each filter. A strong relationship between the ratios of REEs retained in the filtrate solutions and the ionic radii of the associated REEs was observed; i.e. smaller REEs occur in larger proportions dissolved in the solution phase under the conditions of the Horonobe groundwater. The NAA and TOF-SIMS analyses revealed that portions of the REEs were trapped by the 0.2 μm pore filter as REE phosphates, which correspond to the species predicted to be predominant by chemical equilibrium calculations for the conditions of the Horonobe groundwater. Additionally, small portions of colloidal REEs were trapped by the 10 kDa and 3 kDa NMWL ultrafilters. These results suggest that phosphate anions play an important role in the chemical behavior of REEs in saline (seawater-based) groundwater, which may be useful for predicting the migration behavior of trivalent actinides released from radioactive waste repositories in the far future. Copyright © 2016 Elsevier Ltd. All rights reserved.

Assessing the Behavior of Typically Lithophile Elements Under Highly Reducing Conditions Relevant to the Planet Mercury

NASA Technical Reports Server (NTRS)

Rowland, Rick, II; Vander Kaaden, Kathleen E.; McCubbin, Francis M.; Danielson, Lisa R.

2017-01-01

With the data returned from the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (lvtESSENGER) mission, there are now numerous constraints on the physical and chemical properties of Mercury, including its surface composition. The high S and low FeO contents observed from MESSENGER suggest a low oxygen fugacity of the present materials on the planet's surface. Most of our understanding of elemental partitioning behavior comes from observations made on terrestrial rocks, but Mercury's oxygen fugacity is far outside the conditions of those samples, estimated at approximately 3-7 log units below the Iron-Wustite (lW) oxygen buffer, several orders of magnitude more reducing than other terrestrial bodies we have data from. With limited oxygen available, lithophile elements may instead exhibit chalcophile, halophile, or siderophile behaviors. Furthermore, very few natural samples of rocks that formed under reducing conditions (e.g., enstatite chondrites, achondrites, aubrites) are available in our collections for examination of this change in geochemical affinity. Our goal is to determine the elemental partitioning behavior of typically lithophile elements at lower oxygen fugacity as a function of temperature and pressure. Experiments were conducted at I GPa in a 13 mm QUICKpress piston cylinder and at 4 GPa in an 880-ton multi-anvil press, at temperatures up to 1850 C. The composition of starting materials for the experiments were designed so the final run products contained metal, silicate melt, and sulfide melt phases. Oxygen fugacity was controlled in the experiments by adding silicon metal to the samples, in order to utilize the Si-Si02 buffer, which is approx. 5 log units more reducing than the IW buffer at our temperatures of interest. The target silicate melt composition was diopside (CaMgSi206) because measured surface compositions indicate partial melting of a pyroxene-rich mantle. The results of our experiments will aid in our understanding of the fate of elements during the differentiation and thermal evolution of Mercury and other highly reducing planetary bodies.

Assessing the Behavior of Typically Lithophile Elements Under Highly Reducing Conditions Relevant to the Planet Mercury

NASA Technical Reports Server (NTRS)

Rowland, Rick, II; Vander Kaaden, Kathleen E.; McCubbin, Francis M.; Danielson, Lisa R.

2017-01-01

With the data returned from the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) mission, there are now numerous constraints on the physical and chemical properties of Mercury, including its surface composition. The high Sand low FeO contents observed from MESSENGER suggest a low oxygen fugacity of the present materials on the planet's surface. Most of our understanding of elemental partitioning behavior comes from observations made on terrestrial rocks, but Mercury's oxygen fugacity is far outside the conditions of those samples, estimated at approximately 3-7 log units below the Iron-Wtistite (lW) oxygen buffer, several orders of magnitude more reducing than other terrestrial bodies we have data from. With limited oxygen available, lithophile elements may instead exhibit chalcophile, halophile, or siderophile behaviors. Furthermore, very few natural samples of rocks that formed under reducing conditions (e.g., enstatite chondrites, achondrites, aubrites) are available in our collections for examination of this change in geochemical affinity. Our goal is to determine the elemental partitioning behavior of typically lithophile elements at lower oxygen fugacity as a function of temperature and pressure. Experiments were conducted at I GPa in a 13 mm QUICKpress piston cylinder and at 4 GPa in an 880-ton multianvil press, at temperatures up to 1850degC. The composition of starting materials for the experiments were designed so the final run products contained metal, silicate melt, and sulfide melt phases. Oxygen fugacity was controlled in the experiments by adding silicon metal to the samples, in order to utilize the Si-Si02 buffer, which is approximately 5 log units more reducing than the IW buffer at our temperatures of interest. The target silicate melt composition was diopside (CaMgSi206) because measured surface compositions indicate partial melting of a pyroxene-rich mantle. The results of our experiments will aid in our understanding of the fate of elements during the differentiation and thermal evolution of Mercury and other highly reducing planetary bodies.

The Neuropeptide Y system regulates both mechanical and histaminergic itch.

PubMed

Gao, Tianle; Ma, Haisha; Xu, Bo; Bergman, Jessica; Larhammar, Dan; Lagerström, Malin Charlotta

2018-05-24

Itch is a somatosensory modality that serves to alert the organism to harmful elements removable by scratching, such as parasites and chemical irritants. Recently, ablation or silencing of neuropeptide Y (NPY)-expressing spinal interneurons was reported to selectively enhance mechanical itch whereas chemical itch was unaffected. We have examined the effect of activating the NPY/Y 1 receptor system on scratch behavior in mouse. We found that intrathecal administration of the Y 1 agonist [Leu 31 ,Pro 34 ]-NPY (LP-NPY) attenuated itch behavior induced by application of 0.07 g von Frey filament in the nape of the neck, compared to saline treatment, indicating that activation of the spinal NPY/Y 1 system dampens mechanical itch. However, intrathecal administration of LP-NPY also attenuated chemically induced scratching provoked by intradermal application of histamine or the mast cell degranulator 48/80 (histaminergic itch), and the latter effect could be reversed by administration of the Y 1 antagonist BIBO3304. Intrathecal application of the native non-selective agonist NPY also attenuated histamine or 48/80-induced scratching. Our analyses emphasize the importance of including additional quantitative parameters to characterize the full spectrum of itch behavior and show that the NPY/Y 1 system dampens both mechanically and chemically induced scratching and hence is shared by the two sub-modalities of itch. Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.

Structural Dependence of the Sulfur Reduction Mechanism in Carbon-Based Cathodes for Lithium–Sulfur Batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Burgos, Juan C.; Balbuena, Perla B.; Montoya, Javier A.

We report lithium-sulfur batteries are promising non-conventional sources of energy due to their high theoretical capacity and energy density. However, the successful implementation of this technology has been hindered due to the low cycling life of the battery, caused by long chain polysulfide shuttling between electrodes during charge/discharge, among other issues. Quantum chemical calculations are used to study the reactivity of sulfur in the porous cathode of lithium-sulfur batteries, and the retention capabilities of porous carbon materials to avoid long chain polysulfide diffusion. Ab initio molecular dynamics (AIMD) simulations are initially employed to evaluate sulfur reduction mechanisms and kinetics, andmore » to identify main reduction products. A porous cathode architecture is modeled through parallel graphene layers with elemental sulfur rings in the interlayer, and filled with 1,3-dioxolane (DOL) organic solvent and lithium ions. AIMD simulations showed fast reduction of elemental sulfur and formation of short chain polysulfide. Furthermore, the effect of dangling carbon bonds of graphene on the reactivity of the cathode was confirmed. Adsorption calculations through density functional theory (DFT) proved the capacity of small pores to retain long polysulfide chains. An analysis of the effect of the specific current on the chemical behavior of sulfur reveals an influence of current on the amount of sulfur utilization and practical specific capacity of the battery. In conclusion, this work illustrates the physical-chemical behavior of the sulfur/polysulfide in the porous cathode system at atomistic level.« less

Structural Dependence of the Sulfur Reduction Mechanism in Carbon-Based Cathodes for Lithium–Sulfur Batteries

DOE PAGES

Burgos, Juan C.; Balbuena, Perla B.; Montoya, Javier A.

2017-08-17

We report lithium-sulfur batteries are promising non-conventional sources of energy due to their high theoretical capacity and energy density. However, the successful implementation of this technology has been hindered due to the low cycling life of the battery, caused by long chain polysulfide shuttling between electrodes during charge/discharge, among other issues. Quantum chemical calculations are used to study the reactivity of sulfur in the porous cathode of lithium-sulfur batteries, and the retention capabilities of porous carbon materials to avoid long chain polysulfide diffusion. Ab initio molecular dynamics (AIMD) simulations are initially employed to evaluate sulfur reduction mechanisms and kinetics, andmore » to identify main reduction products. A porous cathode architecture is modeled through parallel graphene layers with elemental sulfur rings in the interlayer, and filled with 1,3-dioxolane (DOL) organic solvent and lithium ions. AIMD simulations showed fast reduction of elemental sulfur and formation of short chain polysulfide. Furthermore, the effect of dangling carbon bonds of graphene on the reactivity of the cathode was confirmed. Adsorption calculations through density functional theory (DFT) proved the capacity of small pores to retain long polysulfide chains. An analysis of the effect of the specific current on the chemical behavior of sulfur reveals an influence of current on the amount of sulfur utilization and practical specific capacity of the battery. In conclusion, this work illustrates the physical-chemical behavior of the sulfur/polysulfide in the porous cathode system at atomistic level.« less

PINS chemical identification software

DOEpatents

Caffrey, Augustine J.; Krebs, Kennth M.

2004-09-14

An apparatus and method for identifying a chemical compound. A neutron source delivers neutrons into the chemical compound. The nuclei of chemical elements constituting the chemical compound emit gamma rays upon interaction with the neutrons. The gamma rays are characteristic of the chemical elements constituting the chemical compound. A spectrum of the gamma rays is generated having a detection count and an energy scale. The energy scale is calibrated by comparing peaks in the spectrum to energies of pre-selected chemical elements in the spectrum. A least-squares fit completes the calibration. The chemical elements constituting the chemical compound can be readily determined, which then allows for identification of the chemical compound.

Effect of Elemental Sulfur and Sulfide on the Corrosion Behavior of Cr-Mo Low Alloy Steel for Tubing and Tubular Components in Oil and Gas Industry.

PubMed

Khaksar, Ladan; Shirokoff, John

2017-04-20

The chemical degradation of alloy components in sulfur-containing environments is a major concern in oil and gas production. This paper discusses the effect of elemental sulfur and its simplest anion, sulfide, on the corrosion of Cr-Mo alloy steel at pH 2 and 5 during 10, 20 and 30 h immersion in two different solutions. 4130 Cr-Mo alloy steel is widely used as tubing and tubular components in sour services. According to the previous research in aqueous conditions, contact of solid sulfur with alloy steel can initiate catastrophic corrosion problems. The corrosion behavior was monitored by the potentiodynamic polarization technique during the experiments. Energy dispersive X-ray spectroscopy (EDS) and scanning electron microscopy (SEM) have been applied to characterize the corrosion product layers after each experiment. The results show that under the same experimental conditions, the corrosion resistance of Cr-Mo alloy in the presence of elemental sulfur is significantly lower than its resistance in the presence of sulfide ions.

NTREES Testing and Operations Status

NASA Technical Reports Server (NTRS)

Emrich, Bill

2007-01-01

Nuclear Thermal Rockets or NTR's have been suggested as a propulsion system option for vehicles traveling to the moon or Mars. These engines are capable of providing high thrust at specific impulses at least twice that of today's best chemical engines. The performance constraints on these engines are mainly the result of temperature limitations on the fuel coupled with a limited ability to withstand chemical attack by the hot hydrogen propellant. To operate at maximum efficiency, fuel forms are desired which can withstand the extremely hot, hostile environment characteristic of NTR operation for at least several hours. The simulation of such an environment would require an experimental device which could simultaneously approximate the power, flow, and temperature conditions which a nuclear fuel element (or partial element) would encounter during NTR operation. Such a simulation would allow detailed studies of the fuel behavior and hydrogen flow characteristics under reactor like conditions to be performed. Currently, the construction of such a simulator has been completed at the Marshall Space Flight Center, and will be used in the future to evaluate a wide variety of fuel element designs and the materials of which they are fabricated. This present work addresses the operational status of the Nuclear Thermal Rocket Element Environmental Simulator or NTREES and some of the design considerations which were considered prior to and during its construction.

Chemical speciation and bioavailability of rare earth elements (REEs) in the ecosystem: a review.

PubMed

Khan, Aysha Masood; Bakar, Nor Kartini Abu; Bakar, Ahmad Farid Abu; Ashraf, Muhammad Aqeel

2017-10-01

Rare earths (RE), chemically uniform group of elements due to similar physicochemical behavior, are termed as lanthanides. Natural occurrence depends on the geological circumstances and has been of long interest for geologist as tools for further scientific research into the region of ores, rocks, and oceanic water. The review paper mainly focuses to provide scientific literature about rare earth elements (REEs) with potential environmental and health effects in understanding the research. This is the initial review of RE speciation and bioavailability with current initiative toward development needs and research perceptive. In this paper, we have also discussed mineralogy, extraction, geochemistry, analytical methods of rare earth elements. In this study, REEs with their transformation and vertical distribution in different environments such as fresh and seawater, sediments, soil, weathering, transport, and solubility have been reported with most recent literature along key methods of findings. Speciation and bioavailability have been discussed in detail with special emphasis on soil, plant, and aquatic ecosystems and their impacts on the environment. This review shows that REE gained more importance in last few years due to their detrimental effects on living organisms, so their speciation, bioavailability, and composition are much more important to evaluate their health risks and are discussed thoroughly as well.

Teaching nuclear science: A cosmological approach

DOE Office of Scientific and Technical Information (OSTI.GOV)

Viola, V.E.

1994-10-01

Theories of the origin of the chemical elements can be used effectively to provide a unifying theme in teaching nuclear phenomena to chemistry students. By tracing the element-producing steps that are thought to characterize the chemical evolution of the universe, one can introduce the basic principles of nuclear nomenclature, structure, reactions, energetics, and decay kinetics in a self-consistent context. This approach has the additional advantage of giving the student a feeling for the origin of the elements and their relative abundances in the solar system. Further, one can logically introduce all of the basic forces and particles of nature, asmore » well as the many analogies between nuclear and atomic systems. The subjects of heavy-element synthesis, dating, and the practical applications of nuclear phenomena fit naturally in this scheme. Within the nucleosynthesis framework it is possible to modify the presentation of nuclear behavior to suit the audience--ranging from an emphasis on description for the beginning student to a quantitative theoretical approach for graduate students. The subject matter is flexible in that the basic principles can be condensed into a few lecture as part of a more general course of expanded into an entire course. The following sections describe this approach, with primary emphasis on teaching at the elementary level.« less

Effect of Load on Friction-Wear Behavior of HVOF-Sprayed WC-12Co Coatings

NASA Astrophysics Data System (ADS)

Yifu, Jin; Weicheng, Kong; Tianyuan, Sheng; Ruihong, Zhang; Dejun, Kong

2017-07-01

A WC-12Co coating was sprayed on AISI H13 hot work mold steel using a high-velocity oxygen fuel. The morphologies, phase compositions, and distributions of chemical elements of the obtained coatings were analyzed using a field emission scanning electron microscope, x-ray diffraction, and energy-dispersive spectroscope (EDS), respectively. The friction-wear behaviors under different loads were investigated using a reciprocating wear tester; the morphologies and distributions of the chemical elements of worn tracks were analyzed using a SEM and its configured EDS, respectively. The results show the reunited grains of WC are held together by the Co binder; the primary phases of the coating are WC, Co, and a small amount of W2C and W, owing to the oxidation and decarburization of WC. Inter-diffusion of Fe and W between the coating and the substrate is shown, which indicates a good coating adhesion. The values of the average coefficient of friction under the loads of 40, 80, and 120 N are 0.29, 0.31, and 0.49, respectively. The WC grains are pulled out of the coating during the sliding wear test, but the coating maintains its integrity, suggesting that the coating is intact and continuously protects the substrate from wearing.

Chemical Disposition of Plutonium in Hanford Site Tank Wastes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Delegard, Calvin H.; Jones, Susan A.

2015-05-07

This report examines the chemical disposition of plutonium (Pu) in Hanford Site tank wastes, by itself and in its observed and potential interactions with the neutron absorbers aluminum (Al), cadmium (Cd), chromium (Cr), iron (Fe), manganese (Mn), nickel (Ni), and sodium (Na). Consideration also is given to the interactions of plutonium with uranium (U). No consideration of the disposition of uranium itself as an element with fissile isotopes is considered except tangentially with respect to its interaction as an absorber for plutonium. The report begins with a brief review of Hanford Site plutonium processes, examining the various means used tomore » recover plutonium from irradiated fuel and from scrap, and also examines the intermediate processing of plutonium to prepare useful chemical forms. The paper provides an overview of Hanford tank defined-waste–type compositions and some calculations of the ratios of plutonium to absorber elements in these waste types and in individual waste analyses. These assessments are based on Hanford tank waste inventory data derived from separately published, expert assessments of tank disposal records, process flowsheets, and chemical/radiochemical analyses. This work also investigates the distribution and expected speciation of plutonium in tank waste solution and solid phases. For the solid phases, both pure plutonium compounds and plutonium interactions with absorber elements are considered. These assessments of plutonium chemistry are based largely on analyses of idealized or simulated tank waste or strongly alkaline systems. The very limited information available on plutonium behavior, disposition, and speciation in genuine tank waste also is discussed. The assessments show that plutonium coprecipitates strongly with chromium, iron, manganese and uranium absorbers. Plutonium’s chemical interactions with aluminum, nickel, and sodium are minimal to non-existent. Credit for neutronic interaction of plutonium with these absorbers occurs only if they are physically proximal in solution or the plutonium present in the solid phase is intimately mixed with compounds or solutions of these absorbers. No information on the potential chemical interaction of plutonium with cadmium was found in the technical literature. Definitive evidence of sorption or adsorption of plutonium onto various solid phases from strongly alkaline media is less clear-cut, perhaps owing to fewer studies and to some well-attributed tests run under conditions exceeding the very low solubility of plutonium. The several studies that are well-founded show that only about half of the plutonium is adsorbed from waste solutions onto sludge solid phases. The organic complexants found in many Hanford tank waste solutions seem to decrease plutonium uptake onto solids. A number of studies show plutonium sorbs effectively onto sodium titanate. Finally, this report presents findings describing the behavior of plutonium vis-à-vis other elements during sludge dissolution in nitric acid based on Hanford tank waste experience gained by lab-scale tests, chemical and radiochemical sample characterization, and full-scale processing in preparation for strontium-90 recovery from PUREX sludges.« less

HISTORY OF THE ORIGIN OF THE CHEMICAL ELEMENTS AND THEIR DISCOVERIES.

DOE Office of Scientific and Technical Information (OSTI.GOV)

HOLDEN,N.E.

What do we mean by a chemical element? A chemical element is matter, all of whose atoms are alike in having the same positive charge on the nucleus and the same number of extra-nuclear electrons. As we shall see in the following elemental review, the origin of the chemical elements show a wide diversity with some of these elements having an origin in antiquity, other elements having been discovered within the past few hundred years and still others have been synthesized within the past fifty years via nuclear reactions on heavy elements since these other elements are unstable and radioactivemore » and do not exist in nature.« less

Tailoring gas sensor arrays via the design of short peptides sequences as binding elements.

PubMed

Mascini, Marcello; Pizzoni, Daniel; Perez, German; Chiarappa, Emilio; Di Natale, Corrado; Pittia, Paola; Compagnone, Dario

2017-07-15

A semi-combinatorial virtual approach was used to prepare peptide-based gas sensors with binding properties towards five different chemical classes (alcohols, aldehydes, esters, hydrocarbons and ketones). Molecular docking simulations were conducted for a complete tripeptide library (8000 elements) versus 58 volatile compounds belonging to those five chemical classes. By maximizing the differences between chemical classes, a subset of 120 tripeptides was extracted and used as scaffolds for generating a combinatorial library of 7912 tetrapeptides. This library was processed in an analogous way to the former. Five tetrapeptides (IHRI, KSDS, LGFD, TGKF and WHVS) were chosen depending on their virtual affinity and cross-reactivity for the experimental step. The five peptides were covalently bound to gold nanoparticles by adding a terminal cysteine to each tetrapeptide and deposited onto 20MHz quartz crystal microbalances to construct the gas sensors. The behavior of peptides after this chemical modification was simulated at the pH range used in the immobilization step. ΔF signals analyzed by principal component analysis matched the virtually screened data. The array was able to clearly discriminate the 13 volatile compounds tested based on their hydrophobicity and hydrophilicity molecules as well as the molecular weight. Copyright © 2016 Elsevier B.V. All rights reserved.

Investigation of new semiinsulating behavior of III-V compounds

NASA Technical Reports Server (NTRS)

Lagowski, Jacek

1990-01-01

The investigation of defect interactions and properties related to semiinsulating behavior of III-V semiconductors resulted in about twenty original publications, six doctoral thesis, one masters thesis and numerous conference presentations. The studies of new compensation mechanisms involving transition metal impurities have defined direct effects associated with deep donor/acceptor levels acting as compensating centers. Electrical and optical properties of vanadium and titanium levels were determined in GaAs, InP and also in ternary compounds InGaAs. The experimental data provided basis for the verification of chemical trends and the VRBE method. They also defined compositional range for III-V mixed crystals whereby semiinsulating behavior can be achieved using transition elements deep levels and a suitable codoping with shallow donor/acceptor impurities.

Effect of Silicon on the Activity Coefficient of Rhenium in Fe-Si Liquids: Implications for HSE and Os Isotopes in Planetary Mantles

NASA Technical Reports Server (NTRS)

Righter, K.; Pando, K.; Yang, S.; Humayun, M.

2018-01-01

Metallic cores contain light alloying elements that can be a combination of S, C, Si, and O, all of which have important chemical and physical influences. For Earth, Si may be the most abundant light element in the core. Si dissolved into Fe liquids can have a large effect on the magnitude of the activity coefficient of siderophile elements (SE), and thus the partitioning behavior of those elements between core and mantle. The effect of Si on the highly siderophile elements is only beginning to be studied and the effects on Au, Pd and Pt are significant. Here we report new experiments designed to quantify the effect of Si on the partitioning of Re between metal and silicate melt. A solid understanding of Re partitioning is required for a complete understanding of the Re-Os isotopic systems. The results will be applied to understanding the HSEs and Os isotopic data for planetary mantles, and especially Earth.

Investigation of the behavior of potentially hazardous trace elements in Kentucky coals and combustion byproducts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Robertson, J.D.; Blanchard, L.J.; Srikantapura, S.

1996-12-31

The minor- and trace-element content of coal is of great interest because of the potentially hazardous impact on human health and the environment resulting from their release during coal combustion. Of the one billion tons of coal mined annually in the United States, 85-90% is consumed by coal-fired power plants. Potentially toxic elements present at concentrations as low as a few egg can be released in large quantities from combustion of this magnitude. Of special concern are those trace elements that occur naturally in coal which have been designated as potential hazardous air pollutants (HAPs) in the 1990 Amendments tomore » the Clean Air Act. The principle objective of this work was to investigate a combination of physical and chemical coal cleaning techniques to remove 90 percent of HAP trace elements at 90 percent combustibles recovery from Kentucky No. 9 coal. Samples of this coal were first subjected to physical separation by flotation in a Denver cell. The float fraction from the Denver cell was then used as feed material for hydrothermal leaching tests in which the efficacy of dilute alkali (NaOH) and acid (HNO{sub 3}) solutions at various temperatures and pressures was investigated. The combined column flotation and mild chemical cleaning strategy removed 60-80% of trace elements with greater than 85, recovery of combustibles from very finely ground (-325 mesh) coal. The elemental composition of the samples generated at each stage was determined using particle induced X-ray emission (PIXE) analysis. PIXE is a rapid, instrumental technique that, in principle, is capable of analyzing all elements from sodium through uranium with sensitivities as low as 1 {mu}g/g.« less

[Bioinorganic chemical composition of the lens and methods of its investigation].

PubMed

Avetisov, S E; Novikov, I A; Pakhomova, N A; Motalov, V G

2018-01-01

Bioinorganic chemical composition of the lens of human and experimental animals (cows, dogs, rats, rabbits) have been analyzed in various studies. In most cases, the studies employed different methods to determine the gross (total) composition of chemical elements and their concentrations in the examined samples. Less frequently, they included an assessment of the distribution of chemical elements in the lens and correlation of their concentration with its morphological changes. Chemical elements from all groups (series) of the periodic classification system were discovered in the lens substance. Despite similar investigation methods, different authors obtained contradicting results on the chemical composition of the lens. This article presents data suggesting possible correlation between inorganic chemical elements in the lens substance with the development and formation of lenticular opacities. All currently employed methods are known to only analyze limited number of select chemical elements in the tissues and do not consider the whole range of elements that can be analyzed with existing technology; furthermore, the majority of studies are conducted on the animal model lens. Therefore, it is feasible to continue the development of the chemical microanalysis method by increasing the sensitivity of Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM/EDS) with the purpose of assessing the gross chemical composition and distribution of the elements in the lens substance, as well as revealing possible correlation between element concentration and morphological changes in the lens.

Geochemistry of organic carbon and trace elements in boreal stratified lakes during different seasons

NASA Astrophysics Data System (ADS)

Moreva, O. Y.; Pokrovsky, O. S.; Shirokova, L. S.; Viers, J.

2008-12-01

Our knowledge of chemical fluxes in the system rock-soils-rivers-ocean of boreal and glacial landscapes is limited by the least studied part, i.e., the river water transformation between the lake and the river systems. Dissolved organic carbon (DOC), nutrients, major and trace elements are being leached from soil profile to the river but subjected to chemical transformation in the lakes due to phytoplankton and bacterial activity. As a result, many lakes in boreal regions are quite different in chemical composition compared to surrounding rivers and demonstrate important chemical stratification. The main processes responsible for chemical stratification in lakes are considered to be i) diffusion fluxes from the sediment to the bottom water accompanied by sulfate reduction and methanogenesis in the sediments and ii) dissolution/mineralization of precipitating organic matter (mineral fraction, detritus, plankton pellets) in the bottom layer horizons under anoxic conditions. Up to present time, distinguishing between two processes remains difficult. This paper is aimed at filling this gap via detailed geochemical analysis of DOC and trace elements in the water column profiles of three typical stratified lakes of Arkhangelsk region in Kenozersky National Parc (64° N) in winter (glacial) and in summer period. Concentration of most trace elements (Li, B, Al, Ti, V, Cr, Ni, Co, Zn, As, Rb, Sr, Y, Zr, Mo, Sb, Ba, REEs, Th, U) are not subjected to strong variations along the water column, despite the presence of strong or partial redox stratification. Apparently, these elements are not significantly controlled by production/mineralization processes and redox phenomena in the water column, or the influence of these processes is not pronounced under the control by the allochtonous river water input. In particularly, the stability of titanium and aluminum concentration along the depth profile and their independence of iron behavior suggest the important control by dissolved organic matter. Therefore, organo-ferric colloids controlling petrogenic elements speciation in soil and river waters are being replaced by autochthonous organic colloids in the lake system. The same observation is true for some heavy metals such as nickel, copper and zinc, whereas cobalt, as limiting component, is being strongly removed from the photic zone or it is coprecipitating with manganese hydroxide. Results of the present work allow quantitative evaluation of the role of redox processes in the bottom horizons and organic detritus degradation in the creation of chemical stratification of small lakes with high DOC concentration. Further insights on geochemical migration of trace elements in lakes require : i) study of colloidal speciation using in-situ dialysis; ii) monitoring the annual and seasonal dynamics of redox processes and TE concentration variation along the profile; iii) quantitative assessment of bacterial degradation of suspended OM and Mn and Fe redox reactions along the depth profile; iv) setting the sedimentary traps for evaluation of suspended material fluxes, and, v) thorough study of chemical composition of interstitial pore waters.

Chemical corrosion by chlorides on ancient-like bronzes and treatment by hydrogen glow discharge plasma

NASA Astrophysics Data System (ADS)

Papadopoulou, O.; Novakovic, J.; Vassiliou, P.; Filippaki, E.; Bassiakos, Y.

2013-12-01

Three representative ancient-like bronzes are employed for the chemical synthesis of Cu2(OH)3Cl rich patinas in order to study the influence of the alloying elements in the evolution of the chloride attack and to further conduct stabilization treatment via Hydrogen Glow Discharge Plasma (HGDP) at low temperature and pressure. The corrosion behavior of specimens having Sn and Pb as main alloying elements is governed by a decuprification mechanism and by the formation of Sn-Pb-O enriched barrier layers. In the case of the Zn containing alloy, dezincification is more pronounced at the corrosion initial stages, and copper species predominate the corrosion products evolution. A three-hour HGDP treatment leads to Cu+ production and metallic Cu, Sn, Zn, and Pb redeposition, as a result of metal cation reduction. This process is accompanied by partial removal of Cl species, O diminution, and change in coloration. The further increase of the Cl/O atomic ratio measured on the post-treated surfaces leads to the formation of nantokite and thus to the conclusion that the stabilization of objects with extensive Cl attack is not feasible by HGDP without preliminary chemical treatment.

Dynamics and transformations of radionuclides in soils and ecosystem health

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fellows, Robert J.; Ainsworth, Calvin C.; Driver, Crystal J.

1998-12-01

The chemical behavior of radionuclides can vary widely in soil and sediment environments. Equally important, for a given radionuclide the physico-chemical properties of the solids and aqueous phase can greatly influence a radionuclides behavior. Radionuclides can conceivably occur in soils as soluble-free, inorganic-soluble-complexed, organic-soluble, complexed, adsorbed, precipitated, coprecipitated, or solid structural species. While it is clear that an assessment of a radionuclide?s soil chemistry and potential shifts in speciation will yield a considerable understanding of its behavior in the natural environment, it does not directly translate to bioavailability or its impact on ecosystems health. The soil chemical factors have tomore » be linked to food chain considerations and other ecological parameters that directly tie to an analysis of ecosystem health. In general, the movement of radionuclides from lower to higher trophic levels diminishes with each trophic level in both aqua tic and terrestrial systems. In some cases, transfer is limited because of low absorption/assimilation by successive trophic organisms (Pu, U); for other radionuclides (Tc, H) assimilation may be high but rapid metabolic turnover and low retention greatly reduce tissue concentrations available to predator species. Still others are chemical analogs of essential elements whose concentrations are maintained under strict metabolic control in tissues (Cs) or are stored in tissues seldom consumed by other organisms (Sr storage in exoskeleton, shells, and bone). Therefore, the organisms that receive the greatest ingestion exposures are those in lower trophic positions or are in higher trophic levels but within simple, short food chains. Food source, behavior, and habitat influence the accumulation of radionuclides in animals.« less

An analysis of the effect of defect structures on catalytic surfaces by the boundary element technique

NASA Astrophysics Data System (ADS)

Peirce, Anthony P.; Rabitz, Herschel

1988-08-01

The boundary element (BE) technique is used to analyze the effect of defects on one-dimensional chemically active surfaces. The standard BE algorithm for diffusion is modified to include the effects of bulk desorption by making use of an asymptotic expansion technique to evaluate influences near boundaries and defect sites. An explicit time evolution scheme is proposed to treat the non-linear equations associated with defect sites. The proposed BE algorithm is shown to provide an efficient and convergent algorithm for modelling localized non-linear behavior. Since it exploits the actual Green's function of the linear diffusion-desorption process that takes place on the surface, the BE algorithm is extremely stable. The BE algorithm is applied to a number of interesting physical problems in which non-linear reactions occur at localized defects. The Lotka-Volterra system is considered in which the source, sink and predator-prey interaction terms are distributed at different defect sites in the domain and in which the defects are coupled by diffusion. This example provides a stringent test of the stability of the numerical algorithm. Marginal stability oscillations are analyzed for the Prigogine-Lefever reaction that occurs on a lattice of defects. Dissipative effects are observed for large perturbations to the marginal stability state, and rapid spatial reorganization of uniformly distributed initial perturbations is seen to take place. In another series of examples the effect of defect locations on the balance between desorptive processes on chemically active surfaces is considered. The effect of dynamic pulsing at various time-scales is considered for a one species reactive trapping model. Similar competitive behavior between neighboring defects previously observed for static adsorption levels is shown to persist for dynamic loading of the surface. The analysis of a more complex three species reaction process also provides evidence of competitive behavior between neighboring defect sites. The proposed BE algorithm is shown to provide a useful technique for analyzing the effect of defect sites on chemically active surfaces.

Correlative organelle fluorescence microscopy and synchrotron X-ray chemical element imaging in single cells.

PubMed

Roudeau, Stéphane; Carmona, Asuncion; Perrin, Laura; Ortega, Richard

2014-11-01

X-ray chemical element imaging has the potential to enable fundamental breakthroughs in the understanding of biological systems because chemical element interactions with organelles can be studied at the sub-cellular level. What is the distribution of trace metals in cells? Do some elements accumulate within sub-cellular organelles? What are the chemical species of the elements in these organelles? These are some of the fundamental questions that can be addressed by use of X-ray chemical element imaging with synchrotron radiation beams. For precise location of the distribution of the elements, identification of cellular organelles is required; this can be achieved, after appropriate labelling, by use of fluorescence microscopy. As will be discussed, this approach imposes some limitations on sample preparation. For example, standard immunolabelling procedures strongly modify the distribution of the elements in cells as a result of the chemical fixation and permeabilization steps. Organelle location can, however, be performed, by use of a variety of specific fluorescent dyes or fluorescent proteins, on living cells before cryogenic fixation, enabling preservation of element distribution. This article reviews the methods used for fluorescent organelle labelling and X-ray chemical element imaging and speciation of single cells. Selected cases from our work and from other research groups are presented to illustrate the potential of the combination of the two techniques.

Distribution of trace elements in selected pulverized coals as a function of particle size and density

USGS Publications Warehouse

Senior, C.L.; Zeng, T.; Che, J.; Ames, M.R.; Sarofim, A.F.; Olmez, I.; Huggins, Frank E.; Shah, N.; Huffman, G.P.; Kolker, A.; Mroczkowski, S.; Palmer, C.; Finkelman, R.

2000-01-01

Trace elements in coal have diverse modes of occurrence that will greatly influence their behavior in many coal utilization processes. Mode of occurrence is important in determining the partitioning during coal cleaning by conventional processes, the susceptibility to oxidation upon exposure to air, as well as the changes in physical properties upon heating. In this study, three complementary methods were used to determine the concentrations and chemical states of trace elements in pulverized samples of four US coals: Pittsburgh, Illinois No. 6, Elkhorn and Hazard, and Wyodak coals. Neutron Activation Analysis (NAA) was used to measure the absolute concentration of elements in the parent coals and in the size- and density-fractionated samples. Chemical leaching and X-ray absorption fine structure (XAFS) spectroscopy were used to provide information on the form of occurrence of an element in the parent coals. The composition differences between size-segregated coal samples of different density mainly reflect the large density difference between minerals, especially pyrite, and the organic portion of the coal. The heavy density fractions are therefore enriched in pyrite and the elements associated with pyrite, as also shown by the leaching and XAFS methods. Nearly all the As is associated with pyrite in the three bituminous coals studied. The sub-bituminous coal has a very low content of pyrite and arsenic; in this coal arsenic appears to be primarily organically associated. Selenium is mainly associated with pyrite in the bituminous coal samples. In two bituminous coal samples, zinc is mostly in the form of ZnS or associated with pyrite, whereas it appears to be associated with other minerals in the other two coals. Zinc is also the only trace element studied that is significantly more concentrated in the smaller (45 to 63 ??m) coal particles.

Assessing the Behavior of Typically Lithophile Elements Under Highly Reducing Conditions Relevant to the Planet Mercury

NASA Astrophysics Data System (ADS)

Rowland, R. L., II; Vander Kaaden, K. E.; McCubbin, F. M.; Danielson, L. R.

2017-12-01

With the data returned from the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) mission, there are now numerous constraints on the physical and chemical properties of Mercury, including its surface composition. The high S and low FeO contents observed from MESSENGER suggest a low oxygen fugacity of the present materials on the planet's surface. Most of our understanding of elemental partitioning behavior comes from observations made on terrestrial rocks, but Mercury's oxygen fugacity is far outside the conditions of those samples, estimated at approximately 3-7 log units below the Iron-Wüstite (IW) oxygen buffer, several orders of magnitude more reducing than other terrestrial bodies we have data from. With limited oxygen available, lithophile elements may instead exhibit chalcophile, halophile, or siderophile behaviors. Furthermore, very few natural samples of rocks that formed under reducing conditions (e.g., enstatite chondrites, achondrites, aubrites) are available in our collections for examination of this change in geochemical affinity. Our goal is to determine the elemental partitioning behavior of typically lithophile elements at lower oxygen fugacity as a function of temperature and pressure. Experiments were conducted at 1 GPa in a 13 mm QUICKpress piston cylinder and at 4 GPa in an 880-ton multi-anvil press, at temperatures up to 1850°C. The composition of starting materials for the experiments were designed so the final run products contained metal, silicate melt, and sulfide melt phases. Oxygen fugacity was controlled in the experiments by adding silicon metal to the samples, in order to utilize the Si-SiO2 buffer, which is 5 log units more reducing than the IW buffer at our temperatures of interest. The target silicate melt composition was diopside (CaMgSi2O6) because measured surface compositions indicate partial melting of a pyroxene-rich mantle. The results of our experiments will aid in our understanding of the fate of elements during the differentiation and thermal evolution of Mercury and other highly reducing planetary bodies.

Hair chemical element contents and influence factors of reproductive-age women in the West Ujimqin Banner, Inner Mongolia, China.

PubMed

Zhou, Shanshan; Yuan, Haodong; Ma, Xiaoling; Liu, Ying

2017-01-01

Women have an increased risk for chemical element deficiencies during reproductive age, particularly due to higher chemical element requirements and poor diets. Twenty-one chemical elements (Al, B, Ba, Ca, Cd, Co, Cr, Cu, Fe, Mg, Mn, Mo, Ni, Pb, Se, Si, Sn, Sr, Ti, V and Zn) in hair samples, which were collected from 71 non-pregnant and 236 pregnant women living in the West Ujimqin Banner, central Inner Mongolia, China, were measured, and the environment, dietary habits and ethnic group influence factors associated with the biomarker were analyzed. The results indicated that the average values of the chemical element contents from hair were greatly different compared to those from other areas, especially the Al, Cd, Pb, Ca and Sr contents. There was no significant difference among the three ethnicities for any element except Mn and Ti in non-pregnant women. Compared to non-pregnant women, in the first trimester group, the levels of nine chemical elements (Ba, Cd, Cu, Pb, Se, Si, Sn and Ti) decreased, while the others increased, and the contents of all of the chemical elements decreased in the second trimester group, while in the third trimester, there was a slight increase. Three chemical elements (Cu, Mn and Zn) displayed a synergistic correlation between each other in the third trimester group, which may protect the placenta from some oxidant damage. The high levels of Cd and Pb in hair likely originate from house renovations and traffic pollution. This study provided basic and useful information on the levels of chemical elements in reproductive-age women, and the results of this study are helpful to control the contents and improve the health of pregnant and non-pregnant women. Copyright © 2016 Elsevier Ltd. All rights reserved.

Chinese children with autism: A multiple chemical elements profile in erythrocytes.

PubMed

Wu, Jing; Liu, Duo-Jian; Shou, Xiao-Jing; Zhang, Ji-Shui; Meng, Fan-Chao; Liu, Ya-Qiong; Han, Song-Ping; Zhang, Rong; Jia, Jin-Zhu; Wang, Jing-Yu; Han, Ji-Sheng

2018-06-01

Several lines of evidence suggested that abnormal levels of certain chemical elements may contribute to the development of autism spectrum disorders (ASD). The present work aimed to investigate the multiple chemical elements profile in the erythrocytes of autistic versus typically developing children (TDC) of China. Analyses were carried out to explore the possible association between levels of elements and the risk as well as the severity of ASD. Erythrocyte levels of 11 elements (32%) among 34 detected elements in autistic group were significantly different from those in the TDC group. To our knowledge, this is the first study which compared the levels of rare earth elements in erythrocytes between children with or without ASD. Five elements including Pb, Na, Ca, Sb, and La are associated with the Childhood Autism Rating Scale (CARS) total score. Also, a series of tendencies were found in this research which was believed to affect auditory response, taste, smell, and touch, as well as fear or nervousness. It can be concluded that Chinese autistic children suffer from multi-chemical element imbalances which involves a complex combination of genetic and environmental factors. The results showed a significant correlation between abnormal levels of several chemical elements and the severity of the autistic syndrome. It is suggested that abnormal levels of some chemical elements may contribute to the development of autism spectrum disorders (ASD). In this work, the impact of element imbalances on the risk and severity of ASD was investigated, focusing on the analysis of abnormal levels of the multi-chemical elements profile in erythrocytes compared with typically developing children. Furthermore, the results showed a significant correlation between abnormal levels of several chemical elements and the severity of the autistic syndrome. Autism Res 2018, 11: 834-845. © 2018 International Society for Autism Research, Wiley Periodicals, Inc. © 2018 International Society for Autism Research, Wiley Periodicals, Inc.

Chemistry of superheavy elements.

PubMed

Schädel, Matthias

2006-01-09

The number of chemical elements has increased considerably in the last few decades. Most excitingly, these heaviest, man-made elements at the far-end of the Periodic Table are located in the area of the long-awaited superheavy elements. While physical techniques currently play a leading role in these discoveries, the chemistry of superheavy elements is now beginning to be developed. Advanced and very sensitive techniques allow the chemical properties of these elusive elements to be probed. Often, less than ten short-lived atoms, chemically separated one-atom-at-a-time, provide crucial information on basic chemical properties. These results place the architecture of the far-end of the Periodic Table on the test bench and probe the increasingly strong relativistic effects that influence the chemical properties there. This review is focused mainly on the experimental work on superheavy element chemistry. It contains a short contribution on relativistic theory, and some important historical and nuclear aspects.

Multiple valence superatoms.

PubMed

Reveles, J U; Khanna, S N; Roach, P J; Castleman, A W

2006-12-05

We recently demonstrated that, in gas phase clusters containing aluminum and iodine atoms, an Al(13) cluster behaves like a halogen atom, whereas an Al(14) cluster exhibits properties analogous to an alkaline earth atom. These observations, together with our findings that Al(13)(-) is inert like a rare gas atom, have reinforced the idea that chosen clusters can exhibit chemical behaviors reminiscent of atoms in the periodic table, offering the exciting prospect of a new dimension of the periodic table formed by cluster elements, called superatoms. As the behavior of clusters can be controlled by size and composition, the superatoms offer the potential to create unique compounds with tailored properties. In this article, we provide evidence of an additional class of superatoms, namely Al(7)(-), that exhibit multiple valences, like some of the elements in the periodic table, and hence have the potential to form stable compounds when combined with other atoms. These findings support the contention that there should be no limitation in finding clusters, which mimic virtually all members of the periodic table.

Do stellar and nebular abundances in the Cocoon nebula agree?

NASA Astrophysics Data System (ADS)

García-Rojas, J.; Simón-Díaz, S.; Esteban, C.

2015-05-01

The Cocoon nebula is an apparently spherical Galactic HII region ionized by a single star (BD+46 3474). This nebula seems to be appropriate to investigate the chemical behavior of oxygen and other heavy elements from two different points of view: a detailed analysis of the chemical content of the ionized gas through nebular spectrophotometry and a detailed spectroscopic analysis of the spectrum of the ionizing star using the state-of-the-art stellar atmosphere modelling. In this poster we present the results from a set of high-quality observations, from 2m-4m class telescopes, including the optical spectrum of the ionizing star BD+46 3474, along with long-slit spatially resolved spectroscopy of the nebula. We have used state-of-the-art stellar atmosphere codes to determine stellar parameters and the chemical content of several heavy elements. Traditional nebular techniques along with updated atomic data have been used to compute gaseous abundances of O, N and S in the Cocoon nebula. Thanks to the low ionization degree of the nebula, we could determine total abundances directly from observable ions (no ionization correction factors were needed) for three of the analyzed elements (O, S, and N). The derived stellar and nebular abundances are compared and the influence of the possible presence of the so-called temperature fluctuations on the nebula is discussed. The results of this study are presented in more detail in García-Rojas, Simón-Díaz & Esteban 2014, A&A, 571, A93.

Toxicology of metals and metalloids: Promising issues for future studies in environmental health and toxicology.

PubMed

Barbosa, Fernando

2017-01-01

The function and behavior of chemical elements in ecosystems and in human health probably comprise one of the most studied issues and a theme of great interest and fascination in science. Hot topics are emerging on an annual basis in this field. Bearing this in mind, some promising themes to explore in the field of metals and metalloids in the environment and in toxicology are highlighted and briefly discussed herein.

A finite element method for the thermochemical decomposition of polymeric materials. II - Carbon phenolic composites

NASA Technical Reports Server (NTRS)

Sullivan, R. M.; Salamon, N. J.

1992-01-01

A previously developed formulation for modeling the thermomechanical behavior of chemically decomposing, polymeric materials is verified by simulating the response of carbon phenolic specimens during two high temperature tests: restrained thermal growth and free thermal expansion. Plane strain and plane stress models are used to simulate the specimen response, respectively. In addition, the influence of the poroelasticity constants upon the specimen response is examined through a series of parametric studies.

a Baseline Study of Physico-Chemical Parameters and Trace Metals in Waters of Manakudy, South-West Coast of India

NASA Astrophysics Data System (ADS)

Subramanian, M.; Muthumanikkam, J.

2013-05-01

The transport of trace metals from the land to ocean has a number of different routes and efficiencies. The sources of toxic elements into the rivers to be debouched into the sea through estuaries are either weathered naturally from the soils and rocks or introduced anthropogenically from point or non-point sources, in labile form or in particulate form. However, recent studies indicate that the transport of trace elements to the aquatic environment is much more complex than what has been thought. The chemistry and ecology of an estuarine system are entirely different from the fluvial as well as the marine system. Estuarine environment is characterized by a constantly changing mixture of salt and freshwater. In the present study area Manakudy estuary is situated about 8 kilometres north west of Kanyakumari (Latitude N 08 05 21.8 and Longitude E 077 29 03.7). To gain a better understanding of the geochemical behavior of physico-chemical parameters and trace elements in the estuary and to examine variations in associated chemical changes, 20 water samples were collected throughout the Manakudy estuary, a minor river in south-western India. These samples, collected in typical dry season during 2012, were analyzed for physico-chemical parameters, dissolved major and trace elements. Our results show that dissolved Na, Mg, Ca and Cl behave conservatively along the salinity gradient. The concentration of nutrients is normal and they are due to the higher organic activity in soils as well as faster rates of chemical weathering reaction in the source region. The concentration of major ions is due to tidal influence and it increases with salinity and the nutrients do behave non-conservatively due to biogenic removal. The conservative behaviour of the trace metals with salinity has been strongly affected by the introduction of these metals by external sources. Even though the trace metals in the contaminated water have been removed and incorporated in sediments due to flocculation, the concentration of these metals did not decrease. S.MUTHUSAMY M.sc.,M.phil., RESEARCH SCHOLAR UNIVERSITY OF MADRAS CHENNAI,TAMILNADU INDIA

Chemical sensor

NASA Technical Reports Server (NTRS)

Rauh, R. David (Inventor)

1990-01-01

A sensor for detecting a chemical substance includes an insertion element having a structure which enables insertion of the chemical substance with a resulting change in the bulk electrical characteristics of the insertion element under conditions sufficient to permit effective insertion; the change in the bulk electrical characteristics of the insertion element is detected as an indication of the presence of the chemical substance.

Method for laser induced isotope enrichment

DOEpatents

Pronko, Peter P.; Vanrompay, Paul A.; Zhang, Zhiyu

2004-09-07

Methods for separating isotopes or chemical species of an element and causing enrichment of a desired isotope or chemical species of an element utilizing laser ablation plasmas to modify or fabricate a material containing such isotopes or chemical species are provided. This invention may be used for a wide variety of materials which contain elements having different isotopes or chemical species.

Deciphering the Complex Chemistry of Deep-Ocean Particles Using Complementary Synchrotron X-ray Microscope and Microprobe Instruments.

PubMed

Toner, Brandy M; German, Christopher R; Dick, Gregory J; Breier, John A

2016-01-19

The reactivity and mobility of natural particles in aquatic systems have wide ranging implications for the functioning of Earth surface systems. Particles in the ocean are biologically and chemically reactive, mobile, and complex in composition. The chemical composition of marine particles is thought to be central to understanding processes that convert globally relevant elements, such as C and Fe, among forms with varying bioavailability and mobility in the ocean. The analytical tools needed to measure the complex chemistry of natural particles are the subject of this Account. We describe how a suite of complementary synchrotron radiation instruments with nano- and micrometer focusing, and X-ray absorption spectroscopy (XAS) and X-ray diffraction (XRD) capabilities are changing our understanding of deep-ocean chemistry and life. Submarine venting along mid-ocean ridges creates hydrothermal plumes where dynamic particle-forming reactions occur as vent fluids mix with deep-ocean waters. Whether plumes are net sources or sinks of elements in ocean budgets depends in large part on particle formation, reactivity, and transport properties. Hydrothermal plume particles have been shown to host microbial communities and exhibit complex size distributions, aggregation behavior, and composition. X-ray microscope and microprobe instruments can address particle size and aggregation, but their true strength is in measuring chemical composition. Plume particles comprise a stunning array of inorganic and organic phases, from single-crystal sulfides to poorly ordered nanophases and polymeric organic matrices to microbial cells. X-ray microscopes and X-ray microprobes with elemental imaging, XAS, and XRD capabilities are ideal for investigating these complex materials because they can (1) measure the chemistry of organic and inorganic constituents in complex matrices, usually within the same particle or aggregate, (2) provide strong signal-to-noise data with exceedingly small amounts of material, (3) simplify the chemical complexity of particles or sets of particles with a focused-beam, providing spatial resolution over 6 orders of magnitude (nanometer to millimeter), (4) provide elemental specificity for elements in the soft-, tender-, and hard-X-ray energies, (5) switch rapidly among elements of interest, and (6) function in the presence of water and gases. Synchrotron derived data sets are discussed in the context of important advances in deep-ocean technology, sample handling and preservation, molecular microbiology, and coupled physical-chemical-biological modeling. Particle chemistry, size, and morphology are all important in determining whether particles are reactive with dissolved constituents, provide substrates for microbial respiration and growth, and are delivered to marine sediments or dispersed by deep-ocean currents.

Nutrient elements in large Chinese estuaries

NASA Astrophysics Data System (ADS)

Zhang, Jing

1996-07-01

Based on comprehensive observations since 1983, this study summarizes major features of nutrient elements (nitrogen, phosphorus and silicon) in large Chinese river/estuary systems. Elevated nutrient element levels were observed in Chinese rivers, when compared to large and less disturbed aquatic systems (e.g. the Amazon, Zaire and Orinoco). Data from this study are similar to those obtained from the polluted and/or eutrophic rivers in Europe and North America (e.g. the Rhóne and Loire). Nutrient elements may have either conservative or active distributions, or both, in the mixing zone, depending on the element and the estuary. For example, non-conservative behaviors were observed in the upper estuary, where nutrient elements may be remobilized due to the strong desorption and variations of the fresh water end-member, but conservative distributions were found afterwards in the lower estuary. Outside the riverine effluent plumes, nutrient elements may be depleted in surface waters relative to elevated bioproduction, whereas the regeneration with respect to decomposition of organic material and/or nitrification/denitrification offshore, may sustain high levels of nutrient elements in near-bottom waters. Laboratory experiment data generally compares well with field observations. The high fluxes and area] yields of nutrient elements from large Chinese rivers, indicate the extensive use of chemical fertilizers and domestic waste drainage over watersheds in China.

The Toxicity of Depleted Uranium

PubMed Central

Briner, Wayne

2010-01-01

Depleted uranium (DU) is an emerging environmental pollutant that is introduced into the environment primarily by military activity. While depleted uranium is less radioactive than natural uranium, it still retains all the chemical toxicity associated with the original element. In large doses the kidney is the target organ for the acute chemical toxicity of this metal, producing potentially lethal tubular necrosis. In contrast, chronic low dose exposure to depleted uranium may not produce a clear and defined set of symptoms. Chronic low-dose, or subacute, exposure to depleted uranium alters the appearance of milestones in developing organisms. Adult animals that were exposed to depleted uranium during development display persistent alterations in behavior, even after cessation of depleted uranium exposure. Adult animals exposed to depleted uranium demonstrate altered behaviors and a variety of alterations to brain chemistry. Despite its reduced level of radioactivity evidence continues to accumulate that depleted uranium, if ingested, may pose a radiologic hazard. The current state of knowledge concerning DU is discussed. PMID:20195447

Exploring the Everyday Context of Chemical Elements: Discovering the Elements of Car Components

ERIC Educational Resources Information Center

Franco-Mariscal, Antonio Joaquín

2015-01-01

This paper presents a project about the chemical elements made by 15-year-old Spanish high school students of Chemistry. It focuses on context-based teaching combined with the advantages of creating a large mural which subsequently is exposed in the school. The project consisted of researching the chemical elements in the different materials that…

Trace elements in magnetite as petrogenetic indicators

NASA Astrophysics Data System (ADS)

Dare, Sarah A. S.; Barnes, Sarah-Jane; Beaudoin, Georges; Méric, Julien; Boutroy, Emilie; Potvin-Doucet, Christophe

2014-10-01

We have characterized the distribution of 25 trace elements in magnetite (Mg, Al, Si, P, Ca, Sc, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, Ga, Ge, Y, Zr, Nb, Mo, Sn, Hf, Ta, W, and Pb), using laser ablation ICP-MS and electron microprobe, from a variety of magmatic and hydrothermal ore-forming environments and compared them with data from the literature. We propose a new multielement diagram, normalized to bulk continental crust, designed to emphasize the partitioning behavior of trace elements between magnetite, the melt/fluid, and co-crystallizing phases. The normalized pattern of magnetite reflects the composition of the melt/fluid, which in both magmatic and hydrothermal systems varies with temperature. Thus, it is possible to distinguish magnetite formed at different degrees of crystal fractionation in both silicate and sulfide melts. The crystallization of ilmenite or sulfide before magnetite is recorded as a marked depletion in Ti or Cu, respectively. The chemical signature of hydrothermal magnetite is distinct being depleted in elements that are relatively immobile during alteration and commonly enriched in elements that are highly incompatible into magnetite (e.g., Si and Ca). Magnetite formed from low-temperature fluids has the lowest overall abundance of trace elements due to their lower solubility. Chemical zonation of magnetite is rare but occurs in some hydrothermal deposits where laser mapping reveals oscillatory zoning, which records the changing conditions and composition of the fluid during magnetite growth. This new way of plotting all 25 trace elements on 1 diagram, normalized to bulk continental crust and elements in order of compatibility into magnetite, provides a tool to help understand the processes that control partitioning of a full suit of trace elements in magnetite and aid discrimination of magnetite formed in different environments. It has applications in both petrogenetic and provenance studies, such as in the exploration of ore deposits and in sedimentology.

High Pressure/Temperature Metal Silicate Partitioning of Tungsten

NASA Technical Reports Server (NTRS)

Shofner, G. A.; Danielson, L.; Righter, K.; Campbell, A. J.

2010-01-01

The behavior of chemical elements during metal/silicate segregation and their resulting distribution in Earth's mantle and core provide insight into core formation processes. Experimental determination of partition coefficients allows calculations of element distributions that can be compared to accepted values of element abundances in the silicate (mantle) and metallic (core) portions of the Earth. Tungsten (W) is a moderately siderophile element and thus preferentially partitions into metal versus silicate under many planetary conditions. The partitioning behavior has been shown to vary with temperature, silicate composition, oxygen fugacity, and pressure. Most of the previous work on W partitioning has been conducted at 1-bar conditions or at relatively low pressures, i.e. <10 GPa, and in two cases at or near 20 GPa. According to those data, the stronger influences on the distribution coefficient of W are temperature, composition, and oxygen fugacity with a relatively slight influence in pressure. Predictions based on extrapolation of existing data and parameterizations suggest an increased pressured dependence on metal/ silicate partitioning of W at higher pressures 5. However, the dependence on pressure is not as well constrained as T, fO2, and silicate composition. This poses a problem because proposed equilibration pressures for core formation range from 27 to 50 GPa, falling well outside the experimental range, therefore requiring exptrapolation of a parametereized model. Higher pressure data are needed to improve our understanding of W partitioning at these more extreme conditions.

An ion microprobe study of the intra-crystalline behavior of REE and selected trace elements in pyroxene from mare basalts with different cooling and crystallization histories

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shearer, C.K.; Papike, J.J.; Simon, S.B.

1989-05-01

To study the effects of crystallization sequence and rate on trace element zoning characteristics of pyroxenes, the authors used combined electron microprobe-ion microprobe techniques on four nearly isochemical Apollo 12 and 15 pigeonite basalts with different cooling rates and crystallization histories. Major and minor element zoning characteristics are nearly identical to those reported in the literature. All the pyroxenes have similar chondrite-normalized REE patterns: negative Eu anomalies, positive slopes as defined by Yb/Ce, and slopes of REE patterns from Ce to Sm much steeper than from Gd to Yb. These trace element zoning characteristics in pyroxene and the partitioning ofmore » trace elements between pyroxene and the melt are intimately related to the interplay among the efficiency of the crystallization process, the kinetics at the crystal-melt interface, the kinetics of plagioclase nucleation and the characteristics of the crystal chemical substitutions within both the pyroxene and the associated crystallizing phases (i.e. plagioclase).« less

Trace Elements in River Waters

NASA Astrophysics Data System (ADS)

Gaillardet, J.; Viers, J.; Dupré, B.

2003-12-01

Trace elements are characterized by concentrations lower than 1 mg L-1 in natural waters. This means that trace elements are not considered when "total dissolved solids" are calculated in rivers, lakes, or groundwaters, because their combined mass is not significant compared to the sum of Na+, K+, Ca2+, Mg2+, H4SiO4, HCO3-, CO32-, SO42-, Cl-, and NO3-. Therefore, most of the elements, except about ten of them, occur at trace levels in natural waters. Being trace elements in natural waters does not necessarily qualify them as trace elements in rocks. For example, aluminum, iron, and titanium are major elements in rocks, but they occur as trace elements in waters, due to their low mobility at the Earth's surface. Conversely, trace elements in rocks such as chlorine and carbon are major elements in waters.The geochemistry of trace elements in river waters, like that of groundwater and seawater, is receiving increasing attention. This growing interest is clearly triggered by the technical advances made in the determination of concentrations at lower levels in water. In particular, the development of inductively coupled plasma mass spectrometry (ICP-MS) has considerably improved our knowledge of trace-element levels in waters since the early 1990s. ICP-MS provides the capability of determining trace elements having isotopes of interest for geochemical dating or tracing, even where their dissolved concentrations are extremely low.The determination of trace elements in natural waters is motivated by a number of issues. Although rare, trace elements in natural systems can play a major role in hydrosystems. This is particularly evident for toxic elements such as aluminum, whose concentrations are related to the abundance of fish in rivers. Many trace elements have been exploited from natural accumulation sites and used over thousands of years by human activities. Trace elements are therefore highly sensitive indexes of human impact from local to global scale. Pollution impact studies require knowledge of the natural background concentrations and knowledge of pollutant behavior. For example, it is generally accepted that rare earth elements (REEs) in waters behave as good analogues for the actinides, whose natural levels are quite low and rarely measured. Water quality investigations have clearly been a stimulus for measurement of toxic heavy metals in order to understand their behavior in natural systems.From a more fundamental point of view, it is crucial to understand the behavior of trace elements in geological processes, in particular during chemical weathering and transport by waters. Trace elements are much more fractionated by weathering and transport processes than major elements, and these fractionations give clues for understanding the nature and intensity of the weathering+transport processes. This has not only applications for weathering studies or for the past mobilization and transport of elements to the ocean (potentially recorded in the sediments), but also for the possibility of better utilization of trace elements in the aqueous environment as an exploration tool.In this chapter, we have tried to review the recent literature on trace elements in rivers, in particular by incorporating the results derived from recent ICP-MS measurements. We have favored a "field approach" by focusing on studies of natural hydrosystems. The basic questions which we want to address are the following: What are the trace element levels in river waters? What controls their abundance in rivers and fractionation in the weathering+transport system? Are trace elements, like major elements in rivers, essentially controlled by source-rock abundances? What do we know about the chemical speciation of trace elements in water? To what extent do colloids and interaction with solids regulate processes of trace elements in river waters? Can we relate the geochemistry of trace elements in aquatic systems to the periodic table? And finally, are we able to satisfactorily model and predict the behavior of most of the trace elements in hydrosystems?An impressive literature has dealt with experimental works on aqueous complexation, uptake of trace elements by surface complexation (inorganic and organic), uptake by living organisms (bioaccumulation) that we have not reported here, except when the results of such studies directly explain natural data. As continental waters encompass a greater range of physical and chemical conditions, we focus on river waters and do not discuss trace elements in groundwaters, lakes, and the ocean. In lakes and in the ocean, the great importance of life processes in regulating trace elements is probably the major difference from rivers.Section 5.09.2 of this chapter reports data. We will review the present-day literature on trace elements in rivers to show that our knowledge is still poor. By comparing with the continental abundances, a global mobility index is calculated for each trace element. The spatial and temporal variability of trace-element concentrations in rivers will be shown to be important. In Section 5.09.3, sources of trace elements in river waters are indicated. We will point out the great diversity of sources and the importance of global anthropogenic contamination for a number of elements. The question of inorganic and organic speciation of trace elements in river water will then be addressed in Section 5.09.4, considering some general relationships between speciation and placement in the periodic table. In Section 5.09.5, we will show that studies on organic-rich rivers have led to an exploration of the "colloidal world" in rivers. Colloids are small particles, passing through the conventional filters used to separate dissolved and suspended loads in rivers. They appear as major carriers of trace elements in rivers and considerably complicate aqueous-speciation calculation. Finally, in Section 5.09.6, the significance of interactions between solutes and solid surfaces in river waters will be reviewed. Regulation by surfaces is of major importance for a great range of elements. Although for both colloids and surface interactions, some progress has been made, we are still far from a unified model that can accurately predict trace-element concentrations in natural water systems. This is mainly due to our poor physical description of natural colloids, surface site complexation, and their interaction with solutes.

The discovery of plutonium reorganized the periodic table and aided the discovery of new elements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Clark, David L

2009-01-01

The modern Periodic Table derives principally from the work of the great Russian scientist Dimitri Mendeleev, who in 1869 enunciated a 'periodic law' that the properties of the elements are a periodic function of their atomic weights, and arranged the 65 known elements in a 'periodic table'. Fundamentally, every column in the main body of the Periodic Table is a grouping of elements that display similar chemical and physical behavior. Similar properties are therefore exhibited by elements with widely different mass. Chemical periodicity is central to the study of chemistry, and no other generalization comes close to its ability tomore » systematize and rationalize known chemical facts. With the development of atomic theory, and an understanding of the electronic structure of atoms, chemical periodicity and the periodic table now find their natural explanation in the electronic structure of atoms. Moving from left to right along any row, the elements are arranged sequentially according to nuclear charge (the atomic number). Electrons counter balance that nuclear charge, hence each successive element has one more electron in its configuration. The electron configuration, or distribution of electrons among atomic orbitals, may be determined by application of the Pauli principle (paired spin in the same orbital) and the aufbau principle (which outlines the order of filling of electrons into shells of orbitals - s, p, d, f, etc.) such that in a given atom, no two electrons may have all four quantum numbers identical. In 1939, only three elements were known to be heavier than actinium: thorium, protactinium, and uranium. All three exhibited variable oxidation states and a complex chemistry. Thorium, protactinium and uranium were assumed to be d-transition metals and were placed in the Periodic Table under hafnium, tantalum, and tungsten, respectively. By 1940, McMillan and Abelson bombarded uranium atoms with slow neutrons and successfully identified atoms of element 93, which they named neptunium after the planet Neptune. This rapidly set the stage for the discovery of the next succeeding element, plutonium (Seaborg, McMillan, Kennedy, and Wahl, 1940), named after the next planet away from the Sun, Pluto. The newly discovered elements were presumed to fit comfortably in the Periodic Table under rhenium and osmium, respectively. However, subsequent tracer chemical experiments showed that neptunium and plutonium were closer in their chemical properties to uranium than their presumed homologues, rhenium and osmium. Spectroscopic evidence also indicated that the new elements were not typical transition elements, but had f-electrons in their valence shell. Thus, several researchers, including McMillan and Wahl, and Zachariasen at Los Alamos, suggested that these elements might be part of a second inner-transition series in which the 5f-electron subshell was being filled. It was not clear, however, where the new series would begin. McMillian had proposed a 'uraninide series' that started with neptunium, but attempts to isolate elements with atomic numbers 95 and 96 based on assumed similarities to uranium were unsuccessful. Both Wahl and Zacharias en had proposed a thoride series that started with protactinium. In 1944, Seaborg proposed that the series started with thorium, and that all of the elements heavier than actinium constituted an 'actinide' series similar to the lanthanides. Because the 5f-shell began filling in the same relative position as the 4f-shell, the electronic configuration of elements in the two series would be similar. Guided by the hypothesis that elements 95 and 96 were homologues of europium and gadolinium, new experiments were designed and the elements were uniquely synthesized and separated from all others. The new elements were subsequently named americium and curium. Seaborg's 'Actinide Concept' thus played a major role in the discovery of the transplutonium elements. It provided the framework that supported synthesis, isolation, and identification of the succeeding actinide elements berkelium through lawrencium and beyond to the element with Atomic Number 118. But as research has progressed in the study of the actinide elements, it has become clear that the 5f series has a unique chemistry that is distinct from the lanthanides. One of the focal points of study in actinide research has been to better define the scope and limitations of the actinide concept. Seaborg's actinide concept of heavy element electronic structure, prediction that the actinides form a transition series analogous to the rare earth series of lanthanide elements, is now well accepted in the scientific community and included in all standard configurations of the Periodic Table.« less

Sound velocity of iron-light element compounds and the chemical structure of the inner core

NASA Astrophysics Data System (ADS)

Ohtani, E.; Sakamaki, T.; Fukui, H.; Tanaka, R.; Shibazaki, Y.; Kamada, S.; Sakairi, T.; Takahashi, S.; Tsutsui, S.; Baron, A. Q. R.

2016-12-01

The light elements in the core could constrain the conditions of accretion, subsequent magma ocean, and core formation stages of the Earth. There are several studies for sound velocity measurements of the iron-light elements alloys. However, the measurements are not enough to constrain the light element abundance in the core tightly at present due to inter-laboratory inconsistencies using different methods which are originated from the difficulties to make such measurements under the extreme conditions. We measured the sound velocity of iron alloy compounds at high pressure and temperature relevant to the Earth's core using double-sided laser heating of a DAC combined with inelastic X-ray scattering at SPring-8. We measured the compressional velocity of hcp-Fe up to 166 GPa and 3000 K, and derived a clear temperature dependence of the Birch's law for hcp-Fe. We measured the compressional velocity of Fe0.89Si0.11 alloy and Fe3C at high pressure and temperature, and we could not detect temperature dependency in Birch's law in these compounds. Additionally, we measured the sound velocity of Fe3S, Fe0.83Ni0.09Si0.08 alloy, and FeH at high pressure. Combining our new data set which showed remarkable differences from previous data on the sound velocity, we present a model of the chemical structure of the inner core. The outer core composition was also estimated based on partitioning behaviors of these light elements between solid and liquid iron alloys under the core conditions.

Chemical Imaging Analysis of Environmental Particles Using the Focused Ion Beam/Scanning Electron Microscopy Technique. Microanalysis Insights into Atmospheric Chemistry of Fly Ash

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Haihan; Grassian, Vicki H.; Saraf, Laxmikant V.

2012-11-08

Airborne fly ash from coal combustion may represent a source of bioavailable iron (Fe) in the open ocean. However, few studies have been made focusing on Fe speciation and distribution in coal fly ash. In this study, chemical imaging of fly ash has been performed using a dual-beam FIB/SEM (focused ion beam/scanning electron microscope) system for a better understanding of how simulated atmospheric processing modify the morphology, chemical compositions and element distributions of individual particles. A novel approach has been applied for cross-sectioning of fly ash specimen with a FIB in order to explore element distribution within the interior ofmore » individual particles. Our results indicate that simulated atmospheric processing causes disintegration of aluminosilicate glass, a dominant material in fly ash particles. Aluminosilicate-phase Fe in the inner core of fly ash particles is more easily mobilized compared with oxide-phase Fe present as surface aggregates on fly ash spheres. Fe release behavior depends strongly on Fe speciation in aerosol particles. The approach for preparation of cross-sectioned specimen described here opens new opportunities for particle microanalysis, particular with respect to inorganic refractive materials like fly ash and mineral dust.« less

State of research: environmental pathways and food chain transfer.

PubMed Central

Vaughan, B E

1984-01-01

Data on the chemistry of biologically active components of petroleum, synthetic fuel oils, certain metal elements and pesticides provide valuable generic information needed for predicting the long-term fate of buried waste constituents and their likelihood of entering food chains. Components of such complex mixtures partition between solid and solution phases, influencing their mobility, volatility and susceptibility to microbial transformation. Estimating health hazards from indirect exposures to organic chemicals involves an ecosystem's approach to understanding the unique behavior of complex mixtures. Metabolism by microbial organisms fundamentally alters these complex mixtures as they move through food chains. Pathway modeling of organic chemicals must consider the nature and magnitude of food chain transfers to predict biological risk where metabolites may become more toxic than the parent compound. To obtain predictions, major areas are identified where data acquisition is essential to extend our radiological modeling experience to the field of organic chemical contamination. PMID:6428875

What Is a Chemical Element?

ERIC Educational Resources Information Center

ten Hoor, Marten J.

2017-01-01

Contrary to current IUPAC recommendations, the chemical element X should be defined as the nucleus of the X atom. Consequently, different isotopes with their different nuclei belong to different elements, each one with its own physical and chemical properties. This view leads to the conclusion that we no longer have a periodic table of the…

Contents of chemical elements in stomach during prenatal development: different age-dependent dynamical changes and their significance

PubMed Central

Hou, Shao-Fan; Li, Hai-Rong; Wang, Li-Zhen; Li, De-Zhu; Yang, Lin-Sheng; Li, Chong-Zheng

2003-01-01

AIM: To observe dynamic of different chemical elements in stomach tissue during fetal development. METHODS: To determine contents of the 21 chemical elements in each stomach samples from fetus aging four to ten months. The content values were compared to those from adult tissue samples, and the values for each month group were also analyzed for dynamic changes. RESULTS: Three representations were found regarding the relationship between contents of the elements and ages of the fetus, including the positive correlative (K), reversely correlative (Na, Ca, P, Al, Cu, Zn, Fe, Mn, Cr, Sr, Li, Cd, Ba, Se) and irrelevant groups (Mg, Co, Ni, V, Pb, Ti). CONCLUSION: The chemical elements’ contents in stomach tissues were found to change dynamically with the stomach weights. The age-dependent representations for different chemical elements during the prenatal development may be of some significance for assessing development of fetal stomach and some chemical elements. The data may be helpful for the nutritional balance of fetus and mothers during prenatal development and even the perinatal stages. PMID:12717857

Hypervelocity atmospheric flight: Real gas flow fields

NASA Technical Reports Server (NTRS)

Howe, John T.

1990-01-01

Flight in the atmosphere is examined from the viewpoint of including real gas phenomena in the flow field about a vehicle flying at hypervelocity. That is to say, the flow field is subject not only to compressible phenomena, but is dominated by energetic phenomena. There are several significant features of such a flow field. Spatially, its composition can vary by both chemical and elemental species. The equations which describe the flow field include equations of state and mass, species, elemental, and electric charge continuity; momentum; and energy equations. These are nonlinear, coupled, partial differential equations that were reduced to a relatively compact set of equations of a self-consistent manner (which allows mass addition at the surface at a rate comparable to the free-stream mass flux). The equations and their inputs allow for transport of these quantities relative to the mass-averaged behavior of the flow field. Thus transport of mass by chemical, thermal, pressure, and forced diffusion; transport of momentum by viscosity; and transport of energy by conduction, chemical considerations, viscosity, and radiative transfer are included. The last of these complicate the set of equations by making the energy equation a partial integrodifferential equation. Each phenomenon is considered and represented mathematically by one or more developments. The coefficients which pertain are both thermodynamically and chemically dependent. Solutions of the equations are presented and discussed in considerable detail, with emphasis on severe energetic flow fields. For hypervelocity flight in low-density environments where gaseous reactions proceed at finite rates, chemical nonequilibrium is considered and some illustrations are presented. Finally, flight where the flow field may be out of equilibrium, both chemically and thermodynamically, is presented briefly.

Hypervelocity atmospheric flight: Real gas flow fields

NASA Technical Reports Server (NTRS)

Howe, John T.

1989-01-01

Flight in the atmosphere is examined from the viewpoint of including real gas phenomena in the flow field about a vehicle flying at hypervelocity. That is to say, the flow field is subject not only to compressible phenomena, but is dominated by energetic phenomena. There are several significant features of such a flow field. Spatially, its composition can vary by both chemical and elemental species. The equations which describe the flow field include equations of state and mass, species, elemental, and electric charge continuity; momentum; and energy equations. These are nonlinear, coupled, partial differential equations that have been reduced to a relatively compact set of equations in a self-consistent manner (which allows mass addition at the surface at a rate comparable to the free-stream mass flux). The equations and their inputs allow for transport of these quantities relative to the mass-average behavior of the flow field. Thus transport of mass by chemical, thermal, pressure, and forced diffusion; transport of momentum by viscosity; and transport of energy by conduction, chemical considerations, viscosity, and radiative transfer are included. The last of these complicate the set of equations by making the energy equations a partial integrodifferential equation. Each phenomenon is considered and represented mathematically by one or more developments. The coefficients which pertain are both thermodynamically and chemically dependent. Solutions of the equations are presented and discussed in considerable detail, with emphasis on severe energetic flow fields. Hypervelocity flight in low-density environments where gaseous reactions proceed at finite rates chemical nonequilibrium is considered, and some illustrations are presented. Finally, flight where the flow field may be out of equilibrium, both chemically and thermodynamically, is presented briefly.

On the occurrence of metallic character in the periodic table of the chemical elements.

PubMed

Hensel, Friedrich; Slocombe, Daniel R; Edwards, Peter P

2015-03-13

The classification of a chemical element as either 'metal' or 'non-metal' continues to form the basis of an instantly recognizable, universal representation of the periodic table (Mendeleeff D. 1905 The principles of chemistry, vol. II, p. 23; Poliakoff M. & Tang S. 2015 Phil. Trans. R. Soc. A 373: , 20140211). Here, we review major, pre-quantum-mechanical innovations (Goldhammer DA. 1913 Dispersion und Absorption des Lichtes; Herzfeld KF. 1927 Phys. Rev. 29: , 701-705) that allow an understanding of the metallic or non-metallic status of the chemical elements under both ambient and extreme conditions. A special emphasis will be placed on recent experimental advances that investigate how the electronic properties of chemical elements vary with temperature and density, and how this invariably relates to a changing status of the chemical elements. Thus, the prototypical non-metals, hydrogen and helium, becomes metallic at high densities; and the acknowledged metals, mercury, rubidium and caesium, transform into their non-metallic forms at low elemental densities. This reflects the fundamental fact that, at temperatures above the absolute zero of temperature, there is therefore no clear dividing line between metals and non-metals. Our conventional demarcation of chemical elements as metals or non-metals within the periodic table is of course governed by our experience of the nature of the elements under ambient conditions. Examination of these other situations helps us to examine the exact divisions of the chemical elements into metals and non-metals (Mendeleeff D. 1905 The principles of chemistry, vol. II, p. 23). © 2015 The Author(s) Published by the Royal Society. All rights reserved.

k0-INAA for determining chemical elements in bird feathers

NASA Astrophysics Data System (ADS)

França, Elvis J.; Fernandes, Elisabete A. N.; Fonseca, Felipe Y.; Antunes, Alexsander Z.; Bardini Junior, Claudiney; Bacchi, Márcio A.; Rodrigues, Vanessa S.; Cavalca, Isabel P. O.

2010-10-01

The k0-method instrumental neutron activation analysis ( k0-INAA) was employed for determining chemical elements in bird feathers. A collection was obtained taking into account several bird species from wet ecosystems in diverse regions of Brazil. For comparison reason, feathers were actively sampled in a riparian forest from the Marins Stream, Piracicaba, São Paulo State, using mist nets specific for capturing birds. Biological certified reference materials were used for assessing the quality of analytical procedure. Quantification of chemical elements was performed using the k0-INAA Quantu Software. Sixteen chemical elements, including macro and micronutrients, and trace elements, have been quantified in feathers, in which analytical uncertainties varied from 2% to 40% depending on the chemical element mass fraction. Results indicated high mass fractions of Br (max=7.9 mg kg -1), Co (max=0.47 mg kg -1), Cr (max=68 mg kg -1), Hg (max=2.79 mg kg -1), Sb (max=0.20 mg kg -1), Se (max=1.3 mg kg -1) and Zn (max=192 mg kg -1) in bird feathers, probably associated with the degree of pollution of the areas evaluated. In order to corroborate the use of k0-INAA results in biomonitoring studies using avian community, different factor analysis methods were used to check chemical element source apportionment and locality clustering based on feather chemical composition.

Analysis of the mechanical behavior of single wall carbon nanotubes by a modified molecular structural mechanics model incorporating an advanced chemical force field

NASA Astrophysics Data System (ADS)

Eberhardt, Oliver; Wallmersperger, Thomas

2018-03-01

The outstanding properties of carbon nanotubes (CNTs) keep attracting the attention of researchers from different fields. CNTs are promising candidates for applications e.g. in lightweight construction but also in electronics, medicine and many more. The basis for the realization of the manifold applications is a detailed knowledge of the material properties of the carbon nanotubes. In particular for applications in lightweight constructions or in composites, the knowledge of the mechanical behavior of the CNTs is of vital interest. Hence, a lot of effort is put into the experimental and theoretical determination of the mechanical material properties of CNTs. Due to their small size, special techniques have to be applied. In this research, a modified molecular structural mechanics model for the numerical determination of the mechanical behavior of carbon nanotubes is presented. It uses an advanced approach for the geometrical representation of the CNT structure while the covalent bonds in the CNTs are represented by beam elements. Furthermore, the model is specifically designed to overcome major drawbacks in existing molecular structural mechanics models. This includes energetic consistency with the underlying chemical force field. The model is developed further to enable the application of a more advanced chemical force field representation. The developed model is able to predict, inter alia, the lateral and radial stiffness properties of the CNTs. The results for the lateral stiffness are given and discussed in order to emphasize the progress made with the presented approach.

Electronic Transmutation (ET): Chemically Turning One Element into Another.

PubMed

Zhang, Xinxing; Lundell, Katie A; Olson, Jared K; Bowen, Kit H; Boldyrev, Alexander I

2018-03-08

The concept of electronic transmutation (ET) depicts the processes that by acquiring an extra electron, an element with the atomic number Z begins to have properties that were known to only belong to its neighboring element with the atomic number Z+1. Based on ET, signature compounds and chemical bonds that are composed of certain elements can now be designed and formed by other electronically transmutated elements. This Minireview summarizes the recent developments and applications of ET on both the theoretical and experimental fronts. Examples on the ET of Group 13 elements into Group 14 elements, Group 14 elements into Group 15 elements, and Group 15 elements into Group 16 elements are discussed. Compounds and chemical bonding composed of carbon, silicon, germanium, phosphorous, oxygen and sulfur now have analogues using transmutated boron, aluminum, gallium, silicon, nitrogen, and phosphorous. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

The Role of Chromohalobacter on Transport of Lanthanides and Cesium in the Dolomite Mineral System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zengotita, Frances; Emerson, Hilary Palmer; Dittrich, Timothy M.

2017-12-01

The chemical behavior of actinide series elements and fission products is a concern for the Waste Isolation Pilot Plant repository due to their uncertain mobility in the subsurface salt formation. In this work, we are observing the behavior of the halophilic bacterium, Chromohalobacter, and its effect on the mobility of lanthanides and cesium in the presence of dolomite. Batch and minicolumn experiments were conducted with Cs + and lanthanides (Nd 3+, Eu 3+) to quantify potential transport with bacteria. Preliminary results show that Cs does not interact strongly with dolomite or Chromohalobacter, while the lanthanides can interact strongly with bothmore » minerals and bacteria depending on which the Ln contacts first.« less

Regulation of vernal migration in Gambel's white-crowned sparrows: Role of thyroxine and triiodothyronine.

PubMed

Pérez, Jonathan H; Furlow, J David; Wingfield, John C; Ramenofsky, Marilyn

2016-08-01

Appropriate timing of migratory behavior is critical for migrant species. For many temperate zone birds in the spring, lengthening photoperiod is the initial cue leading to morphological, physiological and behavior changes that are necessary for vernal migration and breeding. Strong evidence has emerged in recent years linking thyroid hormone signaling to the photoinduction of breeding in birds while more limited information suggest a potential role in the regulation of vernal migration in photoperiodic songbirds. Here we investigate the development and expression of the vernal migratory life history stage in captive Gambel's white-crowned sparrows (Zonotrichia leucophrys gambelii) in a hypothyroidic state, induced by chemical inhibition of thyroid hormone production. To explore possible variations in the effects of the two thyroid hormones, triiodothyronine and thyroxine, we subsequently performed a thyroid inhibition coupled with replacement therapy. We found that chemical inhibition of thyroid hormones resulted in complete abolishment of mass gain, fattening, and muscle hypertrophy associated with migratory preparation as well as resulting in failure to display nocturnal restlessness behavior. Replacement of thyroxine rescued all of these elements to near control levels while triiodothyronine replacement displayed partial or delayed rescue. Our findings support thyroid hormones as being necessary for the expression of changes in morphology and physiology associated with migration as well as migratory behavior itself. Copyright © 2016 Elsevier Inc. All rights reserved.

In Situ Industrial Bimetallic Catalyst Characterization using Scanning Transmission Electron Microscopy and X-ray Absorption Spectroscopy at One Atmosphere and Elevated Temperature.

PubMed

Prestat, Eric; Kulzick, Matthew A; Dietrich, Paul J; Smith, Mr Matthew; Tien, Mr Eu-Pin; Burke, M Grace; Haigh, Sarah J; Zaluzec, Nestor J

2017-08-18

We have developed a new experimental platform for in situ scanning transmission electron microscope (STEM) energy dispersive X-ray spectroscopy (EDS) which allows real time, nanoscale, elemental and structural changes to be studied at elevated temperature (up to 1000 °C) and pressure (up to 1 atm). Here we demonstrate the first application of this approach to understand complex structural changes occurring during reduction of a bimetallic catalyst, PdCu supported on TiO 2 , synthesized by wet impregnation. We reveal a heterogeneous evolution of nanoparticle size, distribution, and composition with large differences in reduction behavior for the two metals. We show that the data obtained is complementary to in situ STEM electron energy loss spectroscopy (EELS) and when combined with in situ X-ray absorption spectroscopy (XAS) allows correlation of bulk chemical state with nanoscale changes in elemental distribution during reduction, facilitating new understanding of the catalytic behavior for this important class of materials. © 2017 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

Chemosensory orientation behavior in juvenile sea turtles.

PubMed

Grassman, M

1993-01-01

It has been widely believed for several decades that hatchling sea turtles imprint to chemical cues characteristic of their natal beach and use this information as part of a repertoire of mechanisms enabling their return to the same beach for mating and nesting. This has proven very difficult to test. Although the imprinting theory is conceptually simple, functionally it is quite complex. This involves not only chemical imprinting of nestlings but growth and migration to habitats where the adults are found, long-term memory of their earlier chemical exposure, reproductive maturation, and homing. A few studies have been conducted to examine these elements of the imprinting theory. Experiments involving the exposure of embryos and hatchlings to chemicals suggest that juvenile turtles 'imprint' to the chemical environment of their nest. This can be termed chemical imprinting. Loggerhead turtles, Caretta caretta, and ridley turtles, Lepidochelys kempi, appear to be attracted to chemicals (morpholine and natural seawater, respectively) to which they were exposed as embryos. The strongest support for chemical imprinting is that six-month-old green turtles, Chelonia mydas, exposed to either morpholine or 2-phenylethanol in the nest and for a period of time after hatching, respond similarly to the chemical to which they were exposed as nestlings. Although chemical imprinting does not 'prove' the imprinting theory of turtle homing, it is a necessary component of the theory not previously examined.

Control of trace element toxicity in Chesapeake Bay by dominant phytoplankton. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sanders, J.G.; Riedel, G.F.; Connell, D.B.

1992-02-01

Copper (Cu) and arsenic (As), but not chromium (Cr), underwent large changes in chemical form during the development and senescence of natural phytoplankton blooms. In general, the percentage of organically-associated Cu was lowest during periods of rapid cell growth and highest during periods of cell decline or periods of dominance by red tide-forming dinoflagellates, a pattern tied to periods of release of organic compounds during either bloom senescence or during unusual algal blooms. Chromium, in contrast, was unreactive. The end result of biological mediation of both As and Cu was to increase the proportion of the element present in amore » less toxic form, at least to phytoplankton, thus affecting the potential toxicity of either element to a natural ecosystem. The results of the project provide a framework for the construction of general predictive models of likely trace element behavior in productive ecosystems and provide a conceptual theory of how such toxic contaminants may affect ecosystem structure and food webs within Chesapeake Bay. Predictive models of ecosystem impact will require further experimentation with multi-trophic level food chains.« less

Habitat Use and Trophic Structure in a Highly Migratory Predatory Fish Identified with Geochemical Proxies in Scales

NASA Astrophysics Data System (ADS)

Seeley, M.; Walther, B. D.

2016-02-01

Atlantic tarpon, Megalops atlanticus, are highly migratory euryhaline predators that occupy different habitats throughout ontogeny. Specifically, Atlantic tarpon are known to inhabit oligohaline waters, although the frequency and duration of movements across estuarine gradients into these waters are relatively unknown. This species supports over a two billion dollar industry within the Gulf of Mexico and is currently listed as vulnerable under the International Union for the Conservation of Nature (IUCN). A new non-lethal method for reconstructing migrations across estuaries relies on trace element and stable isotope compositions of growth increments in scales. We analyzed Atlantic tarpon scales from the Texas coast to validate this method using inductively coupled plasma mass spectrometry (ICP-MS) for trace elements and isotope ratio mass spectrometry (IR-MS) for stable isotope ratios. Multiple scales were also taken from the same individual to confirm the consistency of elemental uptake within the same individual. Results show that scale Ba:Ca, Sr:Ca and δ13C are effective proxies for salinity, while enrichments in δ15N are consistent with known ontogenetic trophic shifts. In addition, chemical transects across multiple scales from the same individual were highly consistent, suggesting that any non-regenerated scale removed from a fish can provide equivalent time series. Continuous life history profiles of scales were obtained via laser ablation transects of scale cross-sections to quantify trace element concentrations from the core (youngest increments) to the edge (oldest increments). Stable isotope and trace element results together indicate that behavior is highly variable between individuals, with some but not all fish transiting estuarine gradients into oligohaline waters. Our findings will provide novel opportunities to investigate alternative non-lethal methods to monitor fish migrations across chemical gradients.

The AMBRE Project: r-process element abundances in the Milky Way thin and thick discs

NASA Astrophysics Data System (ADS)

Guiglion, Guillaume; de Laverny, Patrick; Recio-Blanco, Alejandra; Worley, C. Clare

2018-04-01

Chemical evolution of r-process elements in the Milky Way disc is still a matter of debate. We took advantage of high resolution HARPS spectra from the ESO archive in order to derive precise chemical abundances of 3 r-process elements Eu, Dy & Gd for a sample of 4 355 FGK Milky Way stars. The chemical analysis has been performed thanks to the automatic optimization pipeline GAUGUIN. Based on the [α/Fe] ratio, we chemically characterized the thin and the thick discs, and present here results of these 3 r-process element abundances in both discs. We found an unexpected Gadolinium and Dysprosium enrichment in the thick disc stars compared to Europium, while these three elements track well each other in the thin disc.

Highly Reducing Partitioning Experiments Relevant to the Planet Mercury

NASA Technical Reports Server (NTRS)

Rowland, Rick, II; Vander Kaaden, Kathleen E.; McCubbin, Francis M.; Danielson, Lisa R.

2017-01-01

With the data returned from the MErcury Surface Space ENvironment GEochemistry and Ranging (MESSENGER) mission, there are now numerous constraints on the physical and chemical properties of Mercury, including its surface composition. The high S and low FeO contents observed from MESSENGER on the planet's surface suggests a low oxygen fugacity of the present planetary materials. Estimates of the oxygen fugacity for Mercurian magmas are approximately 3-7 log units below the Iron-Wüstite (Fe-FeO) oxygen buffer, several orders of magnitude more reducing than other terrestrial bodies we have data from such as the Earth, Moon, or Mars. Most of our understanding of elemental partitioning behavior comes from observations made on terrestrial rocks, but Mercury's oxygen fugacity is far outside the conditions of those samples. With limited oxygen available, lithophile elements may instead exhibit chalcophile, halophile, or siderophile behaviors. Furthermore, very few natural samples of rocks that formed under reducing conditions are available in our collections (e.g., enstatite chondrites, achondrites, aubrites). With this limited amount of material, we must perform experiments to determine the elemental partitioning behavior of typically lithophile elements as a function of decreasing oxygen fugacity. Experiments are being conducted at 4 GPa in an 880-ton multi-anvil press, at temperatures up to 1850degC. The composition of starting materials for the experiments were selected for the final run products to contain metal, silicate melt, and sulfide melt phases. Oxygen fugacity is controlled in the experiments by adding silicon metal to the samples, using the Si-SiO2 oxygen buffer, which is approximately 5 log units more reducing than the Fe-FeO oxygen buffer at our temperatures of interest. The target silicate melt compositional is diopside (CaMgSi2O6) because measured surface compositions indicate partial melting of a pyroxene-rich mantle. Elements detected on Mercury's surface by MESSENGER (K, Na, Fe, Ti, Cl, Al, Cr, Mn, U, Th) and other geochemically relevant elements (P, F, H, N, C, Co, Ni, Mo, Ce, Nd, Sm, Eu, Gd, Dy, Yb) are added to the starting composition at trace abundances (approximately 500 ppm) so that they are close enough to infinite dilution to follow Henry's law of trace elements, and their partitioning behavior can be measured between the metal, silicate, and sulfide phases. The results of these experiments will allow us to assess the thermal and magmatic evolution of the planet Mercury from a geochemical standpoint.

Researches upon the cavitation erosion behaviour of austenite steels

NASA Astrophysics Data System (ADS)

Bordeasu, I.; Popoviciu, M. O.; Mitelea, I.; Salcianu, L. C.; Bordeasu, D.; Duma, S. T.; Iosif, A.

2016-02-01

Paper analyzes the cavitation erosion behavior of two stainless steels with 100% austenitic structure but differing by the chemical composition and the values of mechanical properties. The research is based on the MDE(t) and MDER(t) characteristic curves. We studied supplementary the aspect of the eroded areas by other to different means: observations with performing optical microscopes and roughness measurements. The tests were done in the T2 vibratory facility in the Cavitation Laboratory of the Timisoara Polytechnic University. The principal purpose of the study is the identification of the elements influencing significantly the cavitation erosion resistance. It was established the effect of the principal chemical components (determining the proportion of the structural components in conformity the Schaffler diagram) upon the cavitation erosion resistance. The results of the researches present the influence of the proportion of unstable austenite upon cavitation erosion resistance. The stainless steel with the great proportion of unstable austenite has the best behavior. The obtained conclusion are important for the metallurgists which realizes the stainless steels used for manufacturing the runners of hydraulic machineries (turbines and pumps) with increased resistance to cavitation attack.

FT-Raman spectroscopy, µ-EDXRF spectrometry, and microhardness analysis of the dentin of primary and permanent teeth.

PubMed

Torres, Carolina Paes; Miranda Gomes-Silva, Jaciara; Menezes-Oliveira, Maria Angélica Hueb; Silva Soares, Luís Eduardo; Palma-Dibb, Regina Guenka; Borsatto, Maria Cristina

2018-05-01

The chemical compositions (organic and inorganic contents) and mechanical behaviors of the dentin of permanent and deciduous teeth were analyzed and compared using X-ray fluorescence spectrometry (µ-EDXRF) Fourier transform Raman spectroscopy (FT-Raman) and a microhardness test (HD). Healthy fresh human primary and permanent molars (n = 10) were selected, The buccal surfaces facing upwards were stabilized in an acrylic plate, flattened, polished, and submitted to the µ-EDXRF, FT-Raman, and HD analysis. The results of the analysis were subjected to ANOVAs and Mann-Whitney U/Student's t multiple comparisons tests. The data showed similar values for the dentin of the primary and permanent teeth in P content, organic content (amide I peak), inorganic content ( PO43- - 430 and 590), and microhardness, Nevertheless, Ca content and Ca/P weight ratio were higher, and the CO32- peak was lower in the dentin of the permanent teeth compared to primary teeth. It be concluded that despite permanent teeth showed more Ca element, both substrates showed similar behavior of chemical and physical properties. © 2018 Wiley Periodicals, Inc.

Fatigue Behavior of Long and Short Cracks in Wrought and Powder Aluminum Alloys.

DTIC Science & Technology

1984-05-01

PROGRAM ELEMENT. PROJECT. TASK AREA & WORK UNIT NUMBERS Robert 0. Ritchie, Department of Materials Science and Mineral Engineering, University of 2306/ Al ...Chemical Compositions in wt% of Alloys Si Fe Cu Mn Mg Cr Zn Ti Zr Al 2024 0.50 0.50 4.50 0.50 1.50 0.10 0.25 0.15 -- balance 2124 0.20 0.30 4.50 0.50 1.50...been applied by Suresh et al .41 to rationalize the microstructural effects of precipitation hardening on fatigue crack growth in 7075 alloys. The

DOE Office of Scientific and Technical Information (OSTI.GOV)

Leggett, Rich

The transition metal yttrium (Y, atomic number 39) is chemically similar to elements in the lanthanide family (atomic numbers 57-71, lanthanum through lutetium) and is always present with the lanthanides in rare earth ores. Yttrium and the lanthanide holmium are particularly close chemical and physical analogues and are referred to as geochemical twins because they typically show little fractionation in geological material. Extensive measurements on rocks, soils, and meteorites indicate that the Y/Ho mass concentration ratio rarely falls far from the “chondritic” or “solar system” ratio of ~26. Our paper presents a new biokinetic model for yttrium in adult humansmore » and examines whether yttrium and holmium may be biological as well as geochemical twins. Collected data on yttrium and holmium in plants and human tissues do not allow precise derivations of Y/Ho concentration ratios but with occasional exceptions yield ratios that are reasonably consistent with chondritic values. Predictions of the time-dependent behavior of yttrium in adult humans based on the yttrium model presented here closely approximate predictions of the behavior of holmium based on a previously developed model for holmium. We know that yttrium and holmium are close biological analogues, but the available comparative data are too limited and imprecise to reveal whether there are any significant differences in their biological behavior.« less

Investigation of the Mixing Behavior and the Generation of Contact-Area in a Continuous Twin-Shaft Kneader

NASA Astrophysics Data System (ADS)

Seck, Oliver; Maxisch, Tobias; Bothe, Dieter; Warnecke, Hans-Joachim

2010-03-01

The technical synthesis and processing of polymer materials is the basis for major branches of the chemical industry. Well introduced for high-viscosity processes are screw extruders. However, in case of large residence times, a kneader with its large volume is more appropriate, but the latter still requires further understanding for intensification purposes. First, the axial mixing behavior is characterized by studying the residence time distribution under continuous operation. For this purpose silicone oil of high viscosity is used as kneading material. At the inlet dye tracer is injected and detected at the outlet via photometry. The response functions show that the classical dispersion model leads to an appropriate description of the experimental data. By means of a fast chemical reaction of second order the radial mixing behavior including transport on the molecular scale is studied. The generation of contact-area between two fluid elements, each one charged with one of the educts is the characteristic quantity since the two reactants cannot coexist and, hence, react directly at the interface. Thus the amount of detected product is a measure for the contact-area produced by kneading. Based on these data, a simplified model for the mixing process in the kneader is developed.

Behavior of Abundances in Chemically Peculiar Dwarf and Subgiant A-Type Stars: HD 23193 and HD 170920

NASA Astrophysics Data System (ADS)

Kılıçoğlu, Tolgahan; Çalışkan, Şeyma; Ünal, Kübraözge

2018-01-01

To understand the origin of the abundance peculiarities of non-magnetic A-type stars, we present the first detailed chemical abundance analysis of a metallic line star HD 23193 (A2m) and an A-type subgiant HD 170920 (A5), which could have been a HgMn star on the main sequence. Our analysis is based on medium (R ∼ 14,000) and high (R ∼ 40,000) resolution spectroscopic data of the stars. The abundances of 18 elements are derived: C, O, Na, Mg, Al, Si, S, Ca, Sc, Ti, Cr, Mn, Fe, Ni, Zn, Sr, Y, and Ba. The masses of HD 23193 and HD 170920 are estimated from evolutionary tracks as 2.3 ± 0.1 M ⊙ and 2.9 ± 0.1 M ⊙. The ages are found to be 635 ± 33 Myr for HD 23193 and 480 ± 50 Myr for HD 170920 using isochrones. The abundance pattern of HD 23193 shows deviations from solar values in the iron-peak elements and indicates remarkable overabundances of Sr (1.16), Y (1.03), and Ba (1.24) with respect to the solar abundances. We compare the derived abundances of this moderately rotating (v\\sin i =37.5 km s‑1) Am star to the theoretical chemical evolution models including rotational mixing. The theoretically predicted abundances resemble our derived abundance pattern, except for a few elements (Si and Cr). For HD 170920, we find nearly solar abundances, except for C (‑0.43), S (0.16), Ti (0.15), Ni (0.16), Zn (0.41), Y (0.57), and Ba (0.97). Its low rotational velocity (v\\sin i=14.5 km s‑1), reduced carbon abundance, and enhanced heavy element abundances suggest that the star is most likely an evolved HgMn star. Based on observations made at the TÜBITAK National Observatory (Program ID 14BRTT150–671), and the Ankara University Observatory, Turkey.

Forms of trace arsenic, cesium, cadmium, and lead transported into river water for the irrigation of Japanese paddy rice fields

NASA Astrophysics Data System (ADS)

Nakaya, Shinji; Chi, Hai; Muroda, Kengo; Masuda, Harue

2018-06-01

In this study, we focus on the behavior of geogenic, toxic trace elements, particularly As, Cs, Cd, and Pb, during their transportation in two rivers for irrigation commonly used in monsoon Asia; one river originates from an active volcano, Mt. Asama, and the other originates from a currently inactive volcano, Yatsugatake Mountains in Nagano, Japan. These rivers were investigated to understand the role of river water as a pollutant of rice and other aquatic plants (via irrigation) and aquatic animals. The results indicated that the behavior of toxic trace elements in river water are likely controlled by their interactions with particulate Fe, Al, and Ti compounds. The majority of Pb and Cd is transported as particulate matter with Fe, Al, and Ti, while the majority of As is transported in the dissolved form, predominantly as arsenate, with low abundance of particulate matter. Cs is transported either as the dissolved form or as particulate matter in both rivers. The investigated elements are transported in the rivers as particulate and dissolved forms, and the ratio of these forms is controlled by the pH and presence of particulate Fe, Al, and Ti phases in the river water. With respect to Cs in both rivers, the parameter governing the concentration and transportation of Cs, in the bimodal form (i.e., particulate and dissolved forms), through the river possibly shifts from sorption to pH by particulate Fe-Al-Ti, according to the abrupt increase in the concentration of Cs in the river. The chemical attraction of particulate Fe-Al-Ti for Cs is weaker than that for Pb and Cd, indicating that the lower electronegativity of Cs weakens the chemical attraction on a colloid for the competitive sorption with the other trace elements. The different relationships between As and Fe in the river and in the irrigation water and soil water, as well as those in paddy rice, suggested that As in paddy rice is not directly derived from As in the irrigation water from the river under flooding.

Two-Dimensional Nonlinear Finite Element Analysis of CMC Microstructures

NASA Technical Reports Server (NTRS)

Mital, Subodh K.; Goldberg, Robert K.; Bonacuse, Peter J.

2011-01-01

Detailed two-dimensional finite element analyses of the cross-sections of a model CVI (chemical vapor infiltrated) SiC/SiC (silicon carbide fiber in a silicon carbide matrix) ceramic matrix composites are performed. High resolution images of the cross-section of this composite material are generated using serial sectioning of the test specimens. These images are then used to develop very detailed finite element models of the cross-sections using the public domain software OOF2 (Object Oriented Analysis of Material Microstructures). Examination of these images shows that these microstructures have significant variability and irregularity. How these variabilities manifest themselves in the variability in effective properties as well as the stress distribution, damage initiation and damage progression is the overall objective of this work. Results indicate that even though the macroscopic stress-strain behavior of various sections analyzed is very similar, each section has a very distinct damage pattern when subjected to in-plane tensile loads and this damage pattern seems to follow the unique architectural and microstructural details of the analyzed sections.

Evaluations of Silica Aerogel-Based Flexible Blanket as Passive Thermal Control Element for Spacecraft Applications

NASA Astrophysics Data System (ADS)

Hasan, Mohammed Adnan; Rashmi, S.; Esther, A. Carmel Mary; Bhavanisankar, Prudhivi Yashwantkumar; Sherikar, Baburao N.; Sridhara, N.; Dey, Arjun

2018-03-01

The feasibility of utilizing commercially available silica aerogel-based flexible composite blankets as passive thermal control element in applications such as extraterrestrial environments is investigated. Differential scanning calorimetry showed that aerogel blanket was thermally stable over - 150 to 126 °C. The outgassing behavior, e.g., total mass loss, collected volatile condensable materials, water vapor regained and recovered mass loss, was within acceptable range recommended for the space applications. ASTM tension and tear tests confirmed the material's mechanical integrity. The thermo-optical properties remained nearly unaltered in simulated space environmental tests such as relative humidity, thermal cycling and thermo-vacuum tests and confirmed the space worthiness of the aerogel. Aluminized Kapton stitched or anchored to the blanket could be used to control the optical transparency of the aerogel. These outcomes highlight the potential of commercial aerogel composite blankets as passive thermal control element in spacecraft. Structural and chemical characterization of the material was also done using scanning electron microscopy, Fourier transform infrared spectroscopy and x-ray photoelectron spectroscopy.

Source/process apportionment of major and trace elements in sinking particles in the Sargasso sea

NASA Astrophysics Data System (ADS)

Huang, S.; Conte, M. H.

2009-01-01

Elemental composition of the particle flux at the Oceanic Flux Program (OFP) time-series site off Bermuda was measured from January 2002 to March 2005. Eighteen elements (Mg, Al, Si, P, Ca, Sc, Ti, V, Mn, Fe, Co, Ni, Cu, Zn, Sr, Cd, Ba and Pb) in sediment trap material from 500, 1500 and 3200 m depths were quantified using fusion-HR-ICPMS. Positive Matrix Factorization (PMF) was used to elucidate sources, elemental associations and processes that affect geochemical behavior in the water column. Results provide evidence for intense elemental cycling between the sinking flux material and the dissolved and suspended pools within mesopelagic and bathypelagic waters. Biological processing and remineralization rapidly deplete the sinking flux material in organic matter and associated elements (N, P, Cd, Zn) between 500 and 1500 m depth. Suspended particle aggregation, authigenic mineral precipitation, and chemical scavenging enriches the flux material in lithogenic minerals, barite and redox sensitive elements (Mn, Co, V, Fe). A large increase in the flux of lithogenic elements is observed with depth and confirms that the northeast Sargasso is a significant sink for advected continental materials, likely supplied via Gulf Stream circulation. PMF resolved major sources that contribute to sinking flux at all depths (carbonate, high-Mg carbonate, opal, organic matter, lithogenic material, and barite) as well as additional depth-specific elemental associations that contribute about half of the compositional variability in the flux. PMF solutions indicate close geochemical associations of barite-opal, Cd-P, Zn-Co, Zn-Pb and redox sensitive elements in the sinking flux material at 500 m depth. Major reorganizations of element associations occur as labile carrier phases break down and elements redistribute among new carrier phases deeper in the water column. Factor scores show strong covariation and similar temporal phasing among the three trap depths and indicate a tight coupling in particle flux compositional variability throughout the water column. Seasonality in flux composition is primarily driven by dilution of the lithogenic component with freshly-produced biogenic material during the late winter primary production maximum. Temporal trends in scores reveal subtle non-seasonal changes in flux composition occurring on month long timescales. This non-seasonal variability may be driven by changes in the biogeochemical properties of intermediate water masses that pass through the region and which affect rates of chemical scavenging and/or aggregation within the water column.

Biogeochemical conversion of sulfur species in saline lakes of Steppe Altai

NASA Astrophysics Data System (ADS)

Borzenko, Svetlana V.; Kolpakova, Marina N.; Shvartsev, Stepan L.; Isupov, Vitaly P.

2017-08-01

The aim of the present research is to identify the main mechanisms of sulfur behavior in saline lakes in the course of time and followed transformations in their chemical composition. The influence of water on chemical composition of biochemical processes involved in decomposition of organic matter was determined by the study of behavior of reduced forms of sulfur in lakes. The determination of reduced forms of sulfur was carried out by successive transfer of each form of sulfur to hydrogen sulfide followed by photometric measurements. The other chemical components were determined by standard methods (atomic absorption, potentiometric method, titration method and others). The salt lakes of the Altai steppe were studied in summer season 2013-2015. Analysis of the chemical composition of the saline lakes of Altai Krai has shown that carbonate-, hydrocarbonate- and chloride ions dominate among anions; sodium is main cation; sulfates are found in subordinate amounts. Reduced forms of sulfur occur everywhere: hydrogen and hydrosulfide sulfur S2- prevail in the bottom sediments; its derivative—elemental S0—prevails in the lakes water. The second important species in water of soda lakes is hydrosulfide sulfur S2-, and in chloride lakes is thiosulfate sulfur S2O3 2- . The lag in the accumulation of sulfates in soda lakes in comparison to chloride lakes can be explained by their bacterial reduction, followed by the formation and deposition of iron sulfides in sediments. In chloride lakes gypsum is a predominantly barrier for sulfates.

The System of Chemical Elements Distribution in the Hydrosphere

NASA Astrophysics Data System (ADS)

Korzh, Vyacheslav D.

2013-04-01

The chemical composition of the hydrosphere is a result of substance migration and transformation on lithosphere-river, river-sea, and ocean-atmosphere boundaries. The chemical elements composition of oceanic water is a fundamental multi-dimensional constant for our planet. Detailed studies revealed three types of chemical element distribution in the ocean: 1) Conservative: concentration normalized to salinity is the constant in space and time; 2) Nutrient-type: element concentration in the surface waters decreases due to the biosphere consumption; and 3) Litho-generative: complex character of distribution of elements, which enter the ocean with the river runoff and interred almost entirely in sediments. The correlation between the chemical elements compositions of the river and oceanic water is high (r = 0.94). We conclude that biogeochemical features of each chemical element are determined by the relationship between its average concentration in the ocean and the intensity of its migration through hydrosphere boundary zones. In our presentation, we shall show intensities of global migration and average concentrations in the ocean in the co ordinates lgC - lg [tau], where C is an average element concentration and [tau] is its residence time in the ocean. We have derived a relationship between three main geochemical parameters of the dissolved forms of chemical elements in the hydrosphere: 1) average concentration in the ocean, 2) average concentration in the river runoff and 3) the type of distribution in oceanic water. Using knowledge of two of these parameters, it allows gaining theoretical knowledge of the third. The System covers all chemical elements for the entire range of observed concentrations. It even allows to predict the values of the annual river transport of dissolved Be, C, N, Ge, Tl, Re, to refine such estimates for P, V, Zn, Br, I, and to determine the character of distribution in the ocean for Au and U. Furthermore, the System allowed estimating natural (unaffected by anthropogenic influence) mean concentrations of elements in the river runoff and using them as ecological reference data. Finally, due to the long response time of the ocean, the mean concentrations of elements and patterns of their distribution in the ocean can be used to determine pre-techno-generative concentrations of elements in the river runoff. In our presentation, we shall show several examples of implementation of the System for studying the sediments' transport by the rivers of the Arctic slope of Northern Eurasia. References 1. Korzh V.D. 1974: Some general laws governing the turnover of substance within the ocean-atmosphere-continent-ocean cycle. Journal de Recherches Atmospheriques, 8, 653-660. 2. Korzh V.D. 2008: The general laws in the formation of the element composition of the Hydrosphere and Biosphere. J. Ecologica, 15, 13-21. 3. Korzh V.D. 2012: Determination of general laws of the chemical element composition in Hydrosphere. Water: Chemistry & Ecology, Journal of Water Science and its Practical Application. No. 1, 56-62.

Geology and geochemistry of endoroique basin case of Baghdad chott southern of Algeria

NASA Astrophysics Data System (ADS)

Lamini, Abdellah; Hacini, Messaoud

2018-05-01

Chott Baghdad is an inland saline lake of the type Na-(Mg)-CI-(SO4). It is situated in septontrional Algerian sahara basin (northern of Africa).these small depression is fall dawn about 31m below sea level. One of characteristic of this zone is dry climate in summer when temperature reach 45°C and decrease in winter 5 °C. Chott Baghdad irrigate with surface water zone, continental saharan aquifer and precipitated water. Evaporative lakes without river outlets are common and their chemical composition has been reported to exhibit a wide diversity (Hardie and Eugster, 1970; Eugster and Hardie, 1978). Geologics and gitologic characteristics of deposed evaporates in Baghdad basin, small closed lagon take place with brines rich in ions SO42 - , Ca2+, Na+, Cl- and under the effect of evaporation generate the rock salt and gypsum precipitation. The objective of this study is to simulate evolution the geochemical cycle inside of chott Baghdad, in addition try to interpreter behavior of major element which constructs this small depression. The most important thing is to calculate saturated index of evaporated mineral and compare it with DRX result. To reach this study, monthly brine samples were collected from January to December. Different analytic methods were used: physico-chemical analytic (PH, temperature and conductivity). In addition, spectrophotometer and titration, phlameemissions were done to calculate major element concentration. From this study, we can conclude that major element behavior (Na+, Cl-, SO42 - , Mg+, K+, HCO3-, and Ca2+) is as follow: Chlore and sodium was decreasing at end of geochemical cycle. In addition, Bicarbonate, potassium and magnesium have characteristic evolution, where they increase at the beginning of geochemical cycle till summer then decrease steadily at the end of cycle. Where us, Calcium is quit steady during one year cycle.

Matching Element Symbols with State Abbreviations: A Fun Activity for Browsing the Periodic Table of Chemical Elements

ERIC Educational Resources Information Center

Woelk, Klaus

2009-01-01

A classroom activity is presented in which students are challenged to find matches between the United States two-letter postal abbreviations for states and chemical element symbols. The activity aims to lessen negative apprehensions students might have when the periodic table of the elements with its more than 100 combinations of letters is first…

Periodic Table of the Elements in the Perspective of Artificial Neural Networks

ERIC Educational Resources Information Center

Lemes, Mauricio R.; Dal Pino, Arnaldo

2011-01-01

Although several chemical elements were not known by end of the 19th century, Mendeleev came up with an astonishing achievement, the periodic table of elements. He was not only able to predict the existence of (then) new elements, but also to provide accurate estimates of their chemical and physical properties. This is a profound example of the…

Our heritage of the elements

NASA Astrophysics Data System (ADS)

Seaborg, Glenn T.

1980-12-01

The role of our heritage of chemical elements, natural and man-made, in determining our accomplishments throughout our history will be described. From the Stone Age, to the beginning of the recent era of understanding of their nature and until the present, mastery of the utilization of the elements has determined the destiny of nations. Whereas even a century ago all but a handful of the elements were mere chemical curiosities, almost all of this great heritage is beginning to be put to use. Today, with our advanced state of knowledge and the incentive of continuing our creative evolution of remaking and fully utilizing our environment, we have sufficient perspective to appreciate just how rich and important is our legacy of the chemical elements. And when the broad, rich, complex spectrum of properties of the pure elements falls short of our needs, we find that we can obtain an enormous variety of properties by combining or mixing them or synthesizing new elements using the Periodic Table as a guiding principle. Our future progress and well being will depend in large part on learning more about the chemical elements and their combinations. These new frontiers continue to be frontiers of the mind.

Our heritage of the elements

NASA Astrophysics Data System (ADS)

Seaborg, Glenn T.

1980-03-01

The role of our heritage of chemical elements, natural and man-made, in determining our accomplishments throughout our history will be described. From the Stone Age, to the beginning of the recent era of understanding of their nature and until the present, mastery of the utilization of the elements has determined the destiny of nations." Whereas even a century ago all but a handful of the elements were mere chemical curiosities, almost all of this great heritage is beginning to be put to use. Today, with our advanced state of knowledge and the incentive of continuing our creative evolution of remaking and fully utilizing our environment, we have sufficient perspective to appreciate just how rich and important is our legacy of the chemical elements. And when the broad, rich, complex spectrum of properties of the pure elements falls short of our needs, we find that we can obtain an enormous variety of properties by combining or mixing them or synthesizing new elements using the Periodic Table as a guiding principle. Our future progress and well being will depend in large part on learning more about the chemical elements and their combinations. These new frontiers continue to be frontiers of the mind.

Shock Wave Propagation in Cementitious Materials at Micro/Meso Scales

NASA Astrophysics Data System (ADS)

Rajendran, Arunachalam

2015-06-01

The mechanical and constitutive response of materials like cement, and bio materials like fish scale and abalone shell is very complex due to heterogeneities that are inherently present in the nano and microstructures. The intrinsic constitutive behaviors are driven by the chemical composition and the molecular, micro, and meso structures. Therefore, it becomes important to identify the material genome as the building block for the material. For instance, in cementitious materials, the genome of C-S-H phase (the glue or the paste) that holds the various clinkers, such as the dicalcium silicate, tricalcium silicate, calcium ferroaluminates, and others is extremely complex. Often mechanical behaviors of C-S-H type materials are influenced by the chemistry and the structures at all nano to micro length scales. By explicitly modeling the molecular structures using appropriate potentials, it is then possible to compute the elastic tensor from molecular dynamics simulations using all atom method. The elastic tensors for the C-S-H gel and other clinkers are determined using the software suite ``Accelrys Materials Studio.'' A strain rate dependent, fracture mechanics based tensile damage model has been incorporated into ABAQUS finite element code to model spall evolution in the heterogeneous cementitious material with all constituents explicitly modeled through one micron element resolution. This paper presents results from nano/micro/meso scale analyses of shock wave propagation in a heterogeneous cementitious material using both molecular dynamic and finite element codes.

Provenance and geochemical behavior of fluorine in the soils of an endemic fluorosis belt, central Iran

NASA Astrophysics Data System (ADS)

Dehbandi, Reza; Moore, Farid; Keshavarzi, Behnam

2017-05-01

The concentration of fluorine, major, trace and rare earth elements (REEs) were used to estimate the probable sources and provenance of fluorine in the soils of an endemic fluorosis belt in central Iran. Total fluorine (TF) in soils varied from 146 to 406 mg/kg with a mean of 277.5 mg/kg. Calculated enrichment factor (EF) and single factor pollution index (SFPI) revealed that the majority of soil samples were moderately contaminated by fluorine. The very strong positive correlation of TF with weathering indices and soil's fine sized fractions indicated that chemical weathering and alteration of parent rocks/soils are the main controlling factors of fluorine behavior in soils. Fluorine affinity to immobile transition trace elements and REEs suggested the role of heavy minerals as the potential F host phases. Modal mineralogy along with SEM-EDX analysis indicated that apatite, fluorapophyllite, epidote, biotite, muscovite and chlorite, as well as, clay minerals are the main F-bearing minerals in the studied soils. Discriminant, bivariate and ternary diagrams of elemental compositions displayed similar geochemical signature of soils to intermediate-acidic rocks and local shales. Based on the weathering indices, soils were immature and showed a non-steady state weathering trend from upper continental crust (UCC), acidic and intermediate igneous source rocks towards shale composition possibly due to mixing of moderately weathered and un-weathered sources of different primary compositions.

Platinum-group elements fractionation by selective complexing, the Os, Ir, Ru, Rh-arsenide-sulfide systems above 1020 °C

NASA Astrophysics Data System (ADS)

Helmy, Hassan M.; Bragagni, Alessandro

2017-11-01

The platinum-group element (PGE) contents in magmatic ores and rocks are normally in the low μg/g (even in the ng/g) level, yet they form discrete platinum-group mineral (PGM) phases. IPGE (Os, Ir, Ru) + Rh form alloys, sulfides, and sulfarsenides while Pt and Pd form arsenides, tellurides, bismuthoids and antimonides. We experimentally investigate the behavior of Os, Ru, Ir and Rh in As-bearing sulfide system between 1300 and 1020 °C and show that the prominent mineralogical difference between IPGE (+Rh) and Pt and Pd reflects different chemical preference in the sulfide melt. At temperatures above 1200 °C, Os shows a tendency to form alloys. Ruthenium forms a sulfide (laurite RuS2) while Ir and Rh form sulfarsenides (irarsite IrAsS and hollingworthite RhAsS, respectively). The chemical preference of PGE is selective: IPGE + Rh form metal-metal, metal-S and metal-AsS complexes while Pt and Pd form semimetal complexes. Selective complexing followed by mechanical separation of IPGE (and Rh)-ligand from Pt- and Pd-ligand associations lead to PGE fractionation.

Measurement of organic and elemental carbon in downtown Rome and background area: physical behavior and chemical speciation.

PubMed

Avino, Pasquale; Manigrasso, Maurizio; Rosada, Alberto; Dodaro, Alessandro

2015-02-01

A significant portion of the particulate matter is the total carbonaceous fraction (or total carbon, TC), composed of two main fractions, elemental carbon (EC) and organic carbon (OC), which shows a large variety of organic compounds, e.g. aliphatic, aromatic compounds, alcohols, acids, etc. In this paper, TC, EC and OC concentrations determined in a downtown Rome urban area are discussed considering the influence of meteorological conditions on the temporal-spatial aerosol distribution. Similar measurements were performed at ENEA Casaccia, an area outside Rome, which is considered as the ome background. Since 2000, TC, EC and OC measurements have been performed by means of an Ambient Carbon Particulate Monitor equipped with a NDIR detector. The EC and OC concentrations trends are compared with benzene and CO trends, which are specific indicators of autovehicular traffic, for identifying the primary EC and OC contributions and the secondary OC fraction origin. Further, a chemical investigation is reported for investigating how the main organic (i.e., n-alkanes, n-alkanoic acids, polyaromatic hydrocarbons and nitro-polyaromatic hydrocarbons) and inorganic (i.e., metals, ions) fractions vary their levels during the investigated period in relationship to new regulations and/or technological innovations.

Chemical studies of elements with Z ⩾ 104 in gas phase

NASA Astrophysics Data System (ADS)

Türler, Andreas; Eichler, Robert; Yakushev, Alexander

2015-12-01

Chemical investigations of superheavy elements in the gas-phase, i.e. elements with Z ≥ 104, allow assessing the influence of relativistic effects on their chemical properties. Furthermore, for some superheavy elements and their compounds quite unique gas-phase chemical properties were predicted. The experimental verification of these properties yields supporting evidence for a firm assignment of the atomic number. Prominent examples are the high volatility observed for HsO4 or the very weak interaction of Cn with gold surfaces. The unique properties of HsO4 were exploited to discover the doubly-magic even-even nucleus 270Hs and the new isotope 271Hs. The combination of kinematic pre-separation and gas-phase chemistry allowed gaining access to a new class of relatively fragile compounds, the carbonyl complexes of elements Sg through Mt. A not yet resolved issue concerns the interaction of Fl with gold surfaces. While competing experiments agree on the fact that Fl is a volatile element, there are discrepancies concerning its adsorption on gold surfaces with respect to its daughter Cn. The elucidation of these and other questions amounts to the fascination that gas-phase chemical investigations exert on current research at the extreme limits of chemistry today.

Investigation on the fates of vanadium and nickel during co-gasification of petroleum coke with biomass.

PubMed

Li, Jiazhou; Wang, Xiaoyu; Wang, Bing; Zhao, Jiantao; Fang, Yitian

2018-06-01

This study investigates the volatilization behaviors and mineral transformation of vanadium and nickel during co-gasification of petroleum coke with biomass. Moreover, the evolution of occurrence modes of vanadium and nickel was also determined by the method of sequential chemical extraction. The results show that the volatilities of vanadium and nickel in petroleum coke have a certain level of growth with an increase in the temperature. With the addition of biomass, their volatilities both show an obvious decrease. Organic matter and stable forms are the dominant chemical forms of vanadium and nickel. After gasification, organic-bound vanadium and nickel decompose completely and convert into other chemical forms. The crystalline phases of vanadium trioxide, coulsonite, nickel sulfide, and elemental nickel are clearly present in petroleum coke and biomass gasification ashes. When the addition of biomass reaches 60 wt%, the diffraction peaks of orthovanadate are found while that of vanadium trioxide disappear. Copyright © 2018 Elsevier Ltd. All rights reserved.

Before Biology: Geologic Habitability and Setting the Chemical and Physical Foundations for Life

NASA Astrophysics Data System (ADS)

Unterborn, Cayman Thomas

The Earth is a habitable, dynamic planet, with plate tectonics creating a deep water and carbon cycle. These cycles regulate surface and atmospheric C and water abundances, and therefore long-term climate, which is vital to Earths habitability. The driving force behind plate tectonics is the convection of the mantle. The fact that the Earth transports its interior heat via convection instead of conduction is a result of a confluence of factors that include the internal energy budget as well as mantle size and composition. Relative to the Sun stars that host extrasolar planets vary in their refractory rock-building element proportions relative to Si by an order of magnitude. This variation will create terrestrial planets with unique mineralogies and dynamical behavior. How similar these planets are to Earth, chemically and physically, is the focus of this proposal with the end goal being to answer: "What variation in planetary chemical composition is capable of supporting the geochemical cycles necessary for life?".

Characterizing suspended sediments from the Piracicaba River Basin by means of k0-INAA

NASA Astrophysics Data System (ADS)

França, E. J.; Fernandes, E. A. N.; Cavalca, I. P. O.; Fonseca, F. Y.; Camilli, L.; Rodrigues, V. S.; Bardini Junior, C.; Ferreira, J. R.; Bacchi, M. A.

2010-10-01

The inorganic chemical characterization of suspended sediments is of utmost relevance for the knowledge of the dynamics and movement of chemical elements in the aquatic and wet ecosystems. Despite the complexity of the effective design for studying this ecological compartment, this work has tested a procedure for analyzing suspended sediments by instrumental neutron activation analysis, k0 method ( k0-INAA). The chemical elements As, Ba, Br, Ca, Ce, Co, Cr, Cs, Eu, Fe, Hf, Hg, K, La, Mo, Na, Ni, Rb, Sb, Sc, Se, Sm, Sr, Ta, Tb, Th, Yb and Zn were quantified in the suspended sediment compartment by means of k0-INAA. When compared with World Average for rivers, high mass fractions of Fe (222,900 mg/kg), Ba (4990 mg/kg), Zn (1350 mg/kg), Cr (646 mg/kg), Co (74.5 mg/kg), Br (113 mg/kg) and Mo (31.9 mg/kg) were quantified in suspended sediments from the Piracicaba River, the Piracicamirim Stream and the Marins Stream. Results of the principal component analysis for standardized chemical element mass fractions indicated an intricate correlation among chemical elements evaluated, as a response of the contribution of natural and anthropogenic sources of chemical elements for ecosystems.

Cheminoes: A Didactic Game to Learn Chemical Relationships between Valence, Atomic Number, and Symbol

ERIC Educational Resources Information Center

Moreno, Luis F.; Hincapié, Gina; Alzate, María Victoria

2014-01-01

Cheminoes is a didactic game that enables the meaningful learning of some relations between concepts such as chemical element, valence, atomic number, and chemical symbol for the first 36 chemical elements of the periodic system. Among the students who have played the game, their opinions of the activity were positive, considering the game to be a…

Closing in on chemical bonds by opening up relativity theory.

PubMed

Whitney, Cynthia K

2008-03-01

This paper develops a connection between the phenomenology of chemical bonding and the theory of relativity. Empirical correlations between electron numbers in atoms and chemical bond stabilities in molecules are first reviewed and extended. Quantitative chemical bond strengths are then related to ionization potentials in elements. Striking patterns in ionization potentials are revealed when the data are viewed in an element-independent way, where element-specific details are removed via an appropriate scaling law. The scale factor involved is not explained by quantum mechanics; it is revealed only when one goes back further, to the development of Einstein's special relativity theory.

Studies of flerovium and element 115 homologs with macrocyclic extractants

NASA Astrophysics Data System (ADS)

Despotopulos, John Dustin

Study of the chemistry of the heaviest elements, Z ? 104, poses a unique challenge due to their low production cross-sections and short half-lives. Chemistry also must be studied on the one-atom-at-a-time scale, requiring automated, fast, and very efficient chemical schemes. Recent studies of the chemical behavior of copernicium (Cn, element 112) and flerovium (Fl, element 114) together with the discovery of isotopes of these elements with half-lives suitable for chemical studies have spurred a renewed interest in the development of rapid systems designed to study the chemical properties of elements with Z ≥ 114. This dissertation explores both extraction chromatography and solvent extraction as methods for development of a rapid chemical separation scheme for the homologs of flerovium (Pb, Sn, Hg) and element 115 (Bi, Sb), with the goal of developing a chemical scheme that, in the future, can be applied to on-line chemistry of both Fl and element 115. Macrocyclic extractants, specifically crown ethers and their derivatives, were chosen for these studies. Carrier-free radionuclides, used in these studies, of the homologs of Fl and element 115 were obtained by proton activation of high purity metal foils at the Lawrence Livermore National Laboratory (LLNL) Center for Accelerator Mass Spectrometry (CAMS): natIn(p,n)113Sn, natSn(p,n)124Sb, and Au(p,n)197m,gHg. The carrier-free activity was separated from the foils by novel separation schemes based on ion exchange and extraction chromatography techniques. Carrier-free Pb and Bi isotopes were obtained from development of a novel generator based on cation exchange chromatography using the 232U parent to generate 212Pb and 212Bi. Crown ethers show high selectivity for metal ions based on their size compared to the negatively charged cavity of the ether. Extraction by crown ethers occur based on electrostatic ion-dipole interactions between the negatively charged ring atoms (oxygen, sulfur, etc.) and the positively charged metal cations. Extraction chromatography resins produced by Eichrom Technologies, specifically the Pb resin based on di-t-byutlcyclohexano-18-crown-6, were chosen as a starting point for these studies. Simple chemical systems based solely on HCl matrices were explored to determine the extent of extraction for Pb, Sn and Hg on the resin. The kinetics and mechanism of extraction were also explored to determine suitability for a Fl chemical experiment. Systems based on KI/HCl and KI/HNO3 were explored for Bi and Sb. In both cases suitable separations, with high separation factors, were performed with vacuum flow columns containing the Pb-resin. Unfortunately the kinetics of uptake for Hg are far too slow on the traditional crown-ether to perform a Fl experiment and obtain whether or not Fl has true Hg-like character or not. However, the kinetics of Pb and Sn are more than sufficient for a Fl experiment to differentiate between Pb- or Sn-like character. To assess this kinetic issue a novel macrocyclic extractant based on sulfur donors was synthesized. Hexathia-18-crown-6, the sulfur analog of 18-crown-6, was synthesized based with by a template reaction using high dilution techniques. The replacement of oxygen ring atoms with sulfur should give the extractant a softer character, which should allow for far greater affinity toward soft metals such as Hg and Pb. From HCl matrices hexathia-18-crown-6 showed far greater kinetics and affinity for Hg than the Pb-resin; however, no affinity for Pb or Sn was seen. This presumably is due to the fact the charge density of sulfur crown ethers does not point to the center of the ring, and future synthesis of a substituted sulfur crown ether which forces the charge density to mimic that of the traditional crown ether should enable extraction of Pb and Sn to a greater extent than with the Pb-resin. Initial studies show promise for the separation of Bi and Sb from HCl matrices using hexathia-18-crown-6. Other macrocyclic extractants, including 2,2,2-cryptand, calix[6]arene and tetrathia-12-crown-4, were also investigated for comparison to the crown ethers. It was noted that these extractants are inferior compared to the crown and thiacrown ethers for extraction of Fl and element 115 homologs. A potential chemical system for Fl was established based on the Eichrom Pb resin, and insight to an improved system based on thiacrown ethers is presented.

Chemical preconcentrator

DOEpatents

Manginell, Ronald P.; Frye-Mason, Gregory C.

2001-01-01

A chemical preconcentrator is disclosed with applications to chemical sensing and analysis. The preconcentrator can be formed by depositing a resistive heating element (e.g. platinum) over a membrane (e.g. silicon nitride) suspended above a substrate. A coating of a sorptive material (e.g. a microporous hydrophobic sol-gel coating or a polymer coating) is formed on the suspended membrane proximate to the heating element to selective sorb one or more chemical species of interest over a time period, thereby concentrating the chemical species in the sorptive material. Upon heating the sorptive material with the resistive heating element, the sorbed chemical species are released for detection and analysis in a relatively high concentration and over a relatively short time period. The sorptive material can be made to selectively sorb particular chemical species of interest while not substantially sorbing other chemical species not of interest. The present invention has applications for use in forming high-sensitivity, rapid-response miniaturized chemical analysis systems (e.g. a "chem lab on a chip").

Thermal-chemical Mantle Convection Models With Adaptive Mesh Refinement

NASA Astrophysics Data System (ADS)

Leng, W.; Zhong, S.

2008-12-01

In numerical modeling of mantle convection, resolution is often crucial for resolving small-scale features. New techniques, adaptive mesh refinement (AMR), allow local mesh refinement wherever high resolution is needed, while leaving other regions with relatively low resolution. Both computational efficiency for large- scale simulation and accuracy for small-scale features can thus be achieved with AMR. Based on the octree data structure [Tu et al. 2005], we implement the AMR techniques into the 2-D mantle convection models. For pure thermal convection models, benchmark tests show that our code can achieve high accuracy with relatively small number of elements both for isoviscous cases (i.e. 7492 AMR elements v.s. 65536 uniform elements) and for temperature-dependent viscosity cases (i.e. 14620 AMR elements v.s. 65536 uniform elements). We further implement tracer-method into the models for simulating thermal-chemical convection. By appropriately adding and removing tracers according to the refinement of the meshes, our code successfully reproduces the benchmark results in van Keken et al. [1997] with much fewer elements and tracers compared with uniform-mesh models (i.e. 7552 AMR elements v.s. 16384 uniform elements, and ~83000 tracers v.s. ~410000 tracers). The boundaries of the chemical piles in our AMR code can be easily refined to the scales of a few kilometers for the Earth's mantle and the tracers are concentrated near the chemical boundaries to precisely trace the evolvement of the boundaries. It is thus very suitable for our AMR code to study the thermal-chemical convection problems which need high resolution to resolve the evolvement of chemical boundaries, such as the entrainment problems [Sleep, 1988].

Anthropophile elements in river sediments: Overview from the Seine River, France

NASA Astrophysics Data System (ADS)

Chen, Jiu-Bin; Gaillardet, Jérôme; Bouchez, Julien; Louvat, Pascale; Wang, Yi-Na

2014-11-01

In contrast to larger river systems that drain relatively pristine basins, little is known about the sediment geochemistry of rivers impacted by intense human activities. In this paper, we present a systematic investigation of the anthropogenic overprints on element geochemistry in sediments of the human-impacted Seine River, France. Most elements are fractionated by grain size, as shown by the comparison between suspended particulate matter (SPM) and riverbank deposits (RBD). The RBD are particularly coarse and enriched in carbonates and heavy minerals and thus in elements such as Ba, Ca, Cr, Hf, Mg, Na, REEs, Sr, Ti, Th, and Zr. Although the enrichment/depletion pattern of some elements (e.g., K, REEs, and Zr) can largely be explained by a binary mixture between two sources, other elements such as Ag, Bi, Cr, Cd, Co, Cu, Fe, Mo, Ni, Pb, Sb, Sn, W, and Zn in SPM in Paris show that a third end-member having anthropogenic characteristics is needed to account for their enrichment at low water stage. These "anthropophile" elements, with high enrichment factors (EFs) relative to the upper continental crust (UCC), display a progressive enrichment downstream and different geochemical behaviors with respect to the hydrodynamic conditions (e.g., grain size) compared to elements having mainly a natural origin. Our findings emphasize the need for systematic studies of these anthropophile elements in other human-impacted rivers using geochemical normalization techniques, and stress the importance of studying the chemical variability associated with hydrodynamic conditions when characterizing riverine element geochemistry and assessing their flux to the ocean.

Adsorption and desorption characteristics of arsenic onto ceria nanoparticles

PubMed Central

2012-01-01

The rapid increase in the use of engineered nanoparticles [ENPs] has resulted in an increasing concern over the potential impacts of ENPs on the environmental and human health. ENPs tend to adsorb a large variety of toxic chemicals when they are emitted into the environment, which may enhance the toxicity of ENPs and/or adsorbed chemicals. The study was aimed to investigate the adsorption and desorption behaviors of arsenic on ceria NPs in aqueous solution using batch technique. Results show that the adsorption behavior of arsenic on ceria NPs was strongly dependent on pH and independent of ionic strength, indicating that the electrostatic effect on the adsorption of these elements was relatively not important compared to surface chemical reactions. The adsorption isotherms fitted very well to both the Langmuir and Freundlich models. The thermodynamic parameters (ΔH0, ΔS0, and ΔG0) for the adsorption of arsenic were determined at three different temperatures of 283, 303, and 323 K. The adsorption reaction was endothermic, and the process of adsorption was favored at high temperature. The desorption data showed that desorption hysteresis occurred at the initial concentration studied. High adsorption capacity of arsenic on ceria NPs suggests that the synergistic effects of ceria NPs and arsenic on the environmental systems may exist when they are released into the environment. PMID:22269298

Gallium isotopic evidence for extensive volatile loss from the Moon during its formation

PubMed Central

Kato, Chizu; Moynier, Frédéric

2017-01-01

The distribution and isotopic composition of volatile elements in planetary materials holds a key to the characterization of the early solar system and the Moon’s formation. The Moon and Earth are chemically and isotopically very similar. However, the Moon is highly depleted in volatile elements and the origin of this depletion is still debated. We present gallium isotopic and elemental measurements in a large set of lunar samples to constrain the origin of this volatile depletion. We show that while Ga has a geochemical behavior different from zinc, both elements show a systematic enrichment in the heavier isotopes in lunar mare basalts and Mg-suite rocks compared to the silicate Earth, pointing to a global-scale depletion event. On the other hand, the ferroan anorthosites are isotopically heterogeneous, suggesting a secondary distribution of Ga at the surface of the Moon by volatilization and condensation. The isotopic difference of Ga between Earth and the Moon and the isotopic heterogeneity of the crustal ferroan anorthosites suggest that the volatile depletion occurred following the giant impact and during the lunar magma ocean phase. These results point toward a Moon that has lost its volatile elements during a whole-scale evaporation event and that is now relatively dry compared to Earth. PMID:28782027

Determination of elemental composition of substance lost following wear of all-ceramic materials.

PubMed

Dündar, Mine; Artunç, Celal; Toksavul, Suna; Ozmen, Dilek; Turgan, Nevbahar

2003-01-01

The aim of this study was to test the possible elemental release of four different all-ceramic materials in a wear machine to predict results about their long-term behavior in the oral environment. Four different all-ceramic materials with different chemical compositions were selected for the wear testing. A total of 20 cylindric samples, five for each ceramic group, were prepared according to the manufacturers' instructions. These were subjected to two-body wear testing in an artificial saliva medium under a covered unit with a computer-operated wear machine. The artificial saliva solutions for each material were analyzed for the determination of amounts of sodium, potassium, calcium, magnesium, and lithium elements released from the glass-ceramic materials. The differences between and within groups were statistically analyzed with a one-way ANOVA, followed by Duncan tests. The statistical analyses revealed no significant differences among Na, K, Ca, or Mg levels (P > .05) released from the leucite-reinforced groups, while there was a significant (P < .05) increase in Li release from the lithium disilicate group. Considerable element release to the artifical saliva medium was demonstrated in short-term wear testing. The lithia-based ceramic was more prone to Li release when compared with other elements and materials.

Determination of rare-earth elements in Luna 16 regolith sample by chemical spectral method

NASA Technical Reports Server (NTRS)

Stroganova, N. S.; Ryabukhin, V. A.; Laktinova, N. V.; Ageyeva, L. V.; Galkina, I. P.; Gatinskaya, N. G.; Yermakov, A. N.; Karyakin, A. V.

1974-01-01

An analysis was made of regolith from layer A of the Luna 16 sample for rare earth elements, by a chemical spectral method. Chemical and ion exchange concentrations were used to determine the content of 12 elements and Y at the level 0.001 to 0.0001 percent with 10 to 15 percent reproducibility of the emission determination. Results within the limits of reproducibility agree with data obtained by mass spectra, activation, and X-ray fluorescent methods.

The behavior of osmium and other siderophile elements during impacts: Insights from the Ries impact structure and central European tektites

NASA Astrophysics Data System (ADS)

Ackerman, Lukáš; Magna, Tomáš; Žák, Karel; Skála, Roman; Jonášová, Šárka; Mizera, Jiří; Řanda, Zdeněk

2017-08-01

Impact processes are natural phenomena that contribute to a variety of physico-chemical mechanisms over an extreme range of shock pressures and temperatures, otherwise seldomly achieved in the Earth's crust through other processes. Under these extreme conditions with transient temperatures and pressures ≥3000 K and ≥100 GPa, followed by their rapid decrease, the behavior of elements has remained poorly understood. Distal glassy ejecta (tektites) were produced in early phases of contact between the Earth's surface and an impacting body. Here we provide evidence for a complex behavior of Os and other highly siderophile elements (HSE; Ir, Ru, Pt, Pd, and Re) during tektite production related to a hyper-velocity impact that formed the Ries structure in Germany. Instead of simple mixing between the surface materials, which are thought to form the major source of central European tektites (moldavites), and impactor matter, the patterns of HSE contents and 187Re/188Os - 187Os/188Os ratios in moldavites, target sediments and impact-related breccias (suevites) can be explained by several sequential and/or contemporary processes. These involve (i) evaporative loss of partially oxidized HSE from the overheated tektite melt, (ii) mixing of target-derived and impactor-derived HSE vapor (plasma) phases, and (iii) early (high-temperature) condensation of a part of the mixed vapor phase back to silicate melt droplets. An almost complete loss of terrestrial Os from the tektite melt and its replacement with extra-terrestrial Os are indicated by low 187Os/188Os ratios in tektites (<0.163) relative to precursor materials (>0.69). This is paralleled by a co-variation between Os and Ni contents in tektites but not in suevites formed later in the impact process.

Experimental constraints on Earth's core formation

NASA Astrophysics Data System (ADS)

Bouhifd, Mohamed Ali

2017-04-01

The Earth contains a Fe-rich metallic core that segregated from the primitive silicate mantle very early in its 4.5 billion year history. One major consequence of this segregation is the depletion of the Earth's mantle from the siderophile elements "high core affinity" relative to primitive solar system abundances. The way in which siderophile elements partition between metal and silicate depends strongly on pressure (P), temperature (T), oxygen fugacity (fO2) and chemical compositions of both metal and silicate phases. In the present presentation, I will discuss the experimental results of metal-silicate partitioning of Ni and Co that show a marked change with increasing pressure (e.g. Bouhifd and Jephcoat, 2011; Siebert et al., 2012; Fischer et al., 2015 for the most recent studies). This behavior coincides with a change in the coordination of silicon (in a basaltic melt composition) from 4-fold coordination under ambient conditions to 6-fold coordination at about 35 GPa, indicating that melt compressibility may controls siderophile-element partitioning (Sanloup et al., 2013). I will also discuss the impact of Earth's core formation on "lithophile" elements such as Sm, Nd, Ta and Nb (e.g. Bouhifd et al. 2015; Cartier et al., 2014), as well as the impact of sulphur on the behavior of various elements during core formation (e.g. Boujibar et al., 2014; Wohlers and Wood, 2015). By combining the metal-silicate partitioning data from siderophile, lithophile and chalcophile elements I will present and discuss the most plausible conditions for Earth's core formation. References Bouhifd and Jephcoat (2011) EPSL, 307, 341-348. Bouhifd et al. (2015) EPSL 413, 158-166. Boujibar et al. (2014) EPSL 391, 42-54. Cartier et al. (2014) Nature Geoscience, 7, 573-576. Fischer et al. (2015) GCA 167, 177-194. Sanloup et al. (2013) Nature, 503, 104-107. Siebert et al. (2012) EPSL 321-322, 189-197. Wohlers and Wood (2015) Nature 520, 337-340.

Investigations on the system boron-carbon silicon

NASA Technical Reports Server (NTRS)

Kieffer, R.; Gugel, E.; Leimer, G.; Ettmayer, P.

1983-01-01

The above elements form with each other binary compounds which are very interesting from the point of view of their structure and their chemistry and which are important for technology. The present investigation is concerned with the three-component system and the behavior of the binary compounds occurring in it. Investigations employing various techniques, such as X-ray, chemical analysis, microscopy and fusion experiments showed that no ternary phase exists within the boundary of the ternary system. There is no compound with a higher abrasion capacity than boron carbide. The probable phase field divisions at two isothermic intersections and the fusion isotherms are indicated.

The abundance and relative volatility of refractory trace elements in Allende Ca,Al-rich inclusions - Implications for chemical and physical processes in the solar nebula

NASA Technical Reports Server (NTRS)

Kornacki, Alan S.; Fegley, Bruce, Jr.

1986-01-01

The relative volatilities of lithophile refractory trace elements (LRTE) were determined using calculated 50-percent condensation temperatures. Then, the refractory trace-element abundances were measured in about 100 Allende inclusions. The abundance patterns found in Allende Ca,Al-rich inclusions (CAIs) and ultrarefractory inclusions were used to empirically modify the calculated LRTE volatility sequence. In addition, the importance of crystal-chemical effects, diffusion constraints, and grain transport for the origin of the trace-element chemistry of Allende CAIs (which have important implications for chemical and physical processes in the solar nebula) is discussed.

Effects of Chemistry on Vertical Dust Motion in Early Protoplanetary Disks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miyazaki, Yoshinori; Korenaga, Jun

We propose the possibility of a new phenomenon affecting the settling of dust grains at the terrestrial region in early protoplanetary disks. Sinking dust grains evaporate in a hot inner region during the early stage of disk evolution, and the effects of condensation and evaporation on vertical dust settling can be significant. A 1D dust settling model considering both physical and chemical aspects is presented in this paper. Modeling results show that dust grains evaporate as they descend into the hotter interior and form a condensation front, above which dust-composing major elements, Mg, Si, and Fe, accumulate, creating a largemore » temperature gradient. Repeated evaporation at the front inhibits grain growth, and small grain sizes elevate the opacity away from the midplane. Self-consistent calculations, including radiative heat transfer and condensation theory, suggest that the mid-disk temperature could be high enough for silicates to remain evaporated longer than previous estimates. The formation of a condensation front leads to contrasting settling behaviors between highly refractory elements, such as Al and Ca, and moderately refractory elements, such as Mg, Si, and Fe, suggesting that elemental abundance in planetesimals may not be a simple function of volatility.« less

Effects of Chemistry on Vertical Dust Motion in Early Protoplanetary Disks

NASA Astrophysics Data System (ADS)

Miyazaki, Yoshinori; Korenaga, Jun

2017-11-01

We propose the possibility of a new phenomenon affecting the settling of dust grains at the terrestrial region in early protoplanetary disks. Sinking dust grains evaporate in a hot inner region during the early stage of disk evolution, and the effects of condensation and evaporation on vertical dust settling can be significant. A 1D dust settling model considering both physical and chemical aspects is presented in this paper. Modeling results show that dust grains evaporate as they descend into the hotter interior and form a condensation front, above which dust-composing major elements, Mg, Si, and Fe, accumulate, creating a large temperature gradient. Repeated evaporation at the front inhibits grain growth, and small grain sizes elevate the opacity away from the midplane. Self-consistent calculations, including radiative heat transfer and condensation theory, suggest that the mid-disk temperature could be high enough for silicates to remain evaporated longer than previous estimates. The formation of a condensation front leads to contrasting settling behaviors between highly refractory elements, such as Al and Ca, and moderately refractory elements, such as Mg, Si, and Fe, suggesting that elemental abundance in planetesimals may not be a simple function of volatility.

Trace Element Composition of Phytoplankton Along the US GEOTRACES Pacific Zonal Transect: Comparing Single-Cell SXRF Quotas, Chemical Leaching, and Bulk Particle Digestion

NASA Astrophysics Data System (ADS)

Ohnemus, D.; Rauschenberg, S.; Twining, B. S.

2014-12-01

The elemental stoichiometries of phytoplankton are critical ecological and chemical parameters due to biological participation in, if not control over, the marine cycles of many GEOTRACES trace elements and isotopes (TEI). Elemental stoichiometries in euphotic zone protists can be used as end-members in biogeochemical models for bioactive elements (e.g. Fe, Si) and can provide insight into relationships found in the deep ocean and sediments (e.g. Cd:P, Zn:Si) due to broad and organism-specific geochemical links. Though sub-euphotic zone (e.g. hydrothermal, margin-sourced lateral) inputs and processes are also interesting aspects of these cycles, biological incorporation of TEIs in the euphotic zone is, fundamentally, where "the rubber meets the road." Using the 2013 Pacific GEOTRACES super stations and Peruvian coastal transect as ecological waypoints, we present and compare results from three methods for studying trace elemental composition of phytoplankton: single-cell synchrotron x-ray fluorescence (SXRF); weak chemical leaching (acetic acid/hydroxylamine); and total chemical digestion (HNO3/HCl/HF). This combination of techniques allows examination of taxon-specific trends in biotic stoichiometry across the Eastern Pacific and also provides traditional bulk chemical metrics for both biotic and bulk shallow particulate composition.

Closing in on Chemical Bonds by Opening up Relativity Theory

PubMed Central

Whitney, Cynthia Kolb

2008-01-01

This paper develops a connection between the phenomenology of chemical bonding and the theory of relativity. Empirical correlations between electron numbers in atoms and chemical bond stabilities in molecules are first reviewed and extended. Quantitative chemical bond strengths are then related to ionization potentials in elements. Striking patterns in ionization potentials are revealed when the data are viewed in an element-independent way, where element-specific details are removed via an appropriate scaling law. The scale factor involved is not explained by quantum mechanics; it is revealed only when one goes back further, to the development of Einstein’s special relativity theory. PMID:19325749

Environmental characteristics and utilization potential of metallurgical slag: Chapter 19

USGS Publications Warehouse

Piatak, Nadine; De Vivo, Benedetto; Belkin, Harvey E.; Lima, Annamaria

2018-01-01

Slag, an abundant byproduct from the pyrometallurgical processing of ores, can be an environmental liability or a valuable resource. The most common environmental impact of slag is from the leaching of potentially toxic elements, acidity, or alkalinity that may impact nearby soils and surface water and groundwater. Factors that influence its environmental behavior include physical characteristics, such as grain size and porosity, chemical composition with some slag being enriched in certain elements, the mineralogy and partitioning of elements in more or less reactive phases, water-slag interactions, and site conditions. Many of these same factors also influence its resource potential. For example, crystalline ferrous slag is most commonly used as construction aggregate, whereas glassy (i.e., granulated) slag is used in cement. Also, the calcium minerals found in ferrous slag result in useful applications in water treatment. In contrast, the high trace-element content of some base-metal slags makes the slags economically attractive for extraction of residual elements. An evaluation tool is used to help categorize a particular slag as an environmental hazard or valuable byproduct. Results for one type of slag, legacy steelmaking slag from the Chicago area in the USA, suggest the material has potential to be used for treating phosphate-rich or acidic waters; however, the pH and trace-element content of resulting solutions may warrant further examination.

Virtual Laboratory as an Element of Visualization When Teaching Chemical Contents in Science Class

ERIC Educational Resources Information Center

Herga, Nataša Rizman; Grmek, Milena Ivanuš; Dinevski, Dejan

2014-01-01

Using a variety of visualization tools for teaching and learning science and chemistry is necessary because pupils better understand chemical phenomena and formulate appropriate mental models. The purpose of the presented study was to determine the importance of a virtual laboratory as a visualization element when addressing chemical contents…

Sensors for detecting analytes in fluids

NASA Technical Reports Server (NTRS)

Lewis, Nathan S. (Inventor); Severin, Erik (Inventor)

1998-01-01

Chemical sensors for detecting analytes in fluids comprise first and second conductive elements (e.g., electrical leads) electrically coupled to and separated by a chemically sensitive resistor which provides an electrical path between the conductive elements. The resistor comprises a plurality of alternating nonconductive regions (comprising a nonconductive organic polymer) and conductive regions (comprising a conductive material) transverse to the electrical path. The resistor provides a difference in resistance between the conductive elements when contacted with a fluid comprising a chemical analyte at a first concentration, than when contacted with a fluid comprising the chemical analyte at a second different concentration. Arrays of such sensors are constructed with at least two sensors having different chemically sensitive resistors providing dissimilar such differences in resistance. Variability in chemical sensitivity from sensor to sensor is provided by qualitatively or quantitatively varying the composition of the conductive and/or nonconductive regions. An electronic nose for detecting an analyte in a fluid may be constructed by using such arrays in conjunction with an electrical measuring device electrically connected to the conductive elements of each sensor.

Sensors for detecting analytes in fluids

NASA Technical Reports Server (NTRS)

Severin, Erik (Inventor); Lewis, Nathan S. (Inventor)

2001-01-01

Chemical sensors for detecting analytes in fluids comprise first and second conductive elements (e.g., electrical leads) electrically coupled to and separated by a chemically sensitive resistor which provides an electrical path between the conductive elements. The resistor comprises a plurality of alternating nonconductive regions (comprising a nonconductive organic polymer) and conductive regions (comprising a conductive material) transverse to the electrical path. The resistor provides a difference in resistance between the conductive elements when contacted with a fluid comprising a chemical analyte at a first concentration, than when contacted with a fluid comprising the chemical analyte at a second different concentration. Arrays of such sensors are constructed with at least two sensors having different chemically sensitive resistors providing dissimilar such differences in resistance. Variability in chemical sensitivity from sensor to sensor is provided by qualitatively or quantitatively varying the composition of the conductive and/or nonconductive regions. An electronic nose for detecting an analyte in a fluid may be constructed by using such arrays in conjunction with an electrical measuring device electrically connected to the conductive elements of each sensor.

Sensors for detecting analytes in fluids

NASA Technical Reports Server (NTRS)

Lewis, Nathan S. (Inventor); Severin, Erik (Inventor)

1999-01-01

Chemical sensors for detecting analytes in fluids comprise first and second conductive elements (e.g., electrical leads) electrically coupled to and separated by a chemically sensitive resistor which provides an electrical path between the conductive elements. The resistor comprises a plurality of alternating nonconductive regions (comprising a nonconductive organic polymer) and conductive regions (comprising a conductive material) transverse to the electrical path. The resistor provides a difference in resistance between the conductive elements when contacted with a fluid comprising a chemical analyte at a first concentration, than when contacted with a fluid comprising the chemical analyte at a second different concentration. Arrays of such sensors are constructed with at least two sensors having different chemically sensitive resistors providing dissimilar such differences in resistance. Variability in chemical sensitivity from sensor to sensor is provided by qualitatively or quantitatively varying the composition of the conductive and/or nonconductive regions. An electronic nose for detecting an analyte in a fluid may be constructed by using such arrays in conjunction with an electrical measuring device electrically connected to the conductive elements of each sensor.

Sensor arrays for detecting analytes in fluids

NASA Technical Reports Server (NTRS)

Lewis, Nathan S. (Inventor); Freund, Michael S. (Inventor)

1996-01-01

Chemical sensors for detecting analytes in fluids comprise first and second conductive elements (e.g. electrical leads) electrically coupled to and separated by a chemically sensitive resistor which provides an electrical path between the conductive elements. The resistor comprises a plurality of alternating nonconductive regions (comprising a nonconductive organic polymer) and conductive regions (comprising a conductive material) transverse to the electrical path. The resistor provides a difference in resistance between the conductive elements when contacted with a fluid comprising a chemical analyte at a first concentration, than when contacted with a fluid comprising the chemical analyte at a second different concentration. Arrays of such sensors are constructed with at least two sensors having different chemically sensitive resistors providing dissimilar such differences in resistance. Variability in chemical sensitivity from sensor to sensor is provided by qualitatively or quantitatively varying the composition of the conductive and/or nonconductive regions. An electronic nose for detecting an analyte in a fluid may be constructed by using such arrays in conjunction with an electrical measuring device electrically connected to the conductive elements of each sensor.

Biokinetics of yttrium and comparison with its geochemical twin holmium

DOE PAGES

Leggett, Rich

2017-06-01

The transition metal yttrium (Y, atomic number 39) is chemically similar to elements in the lanthanide family (atomic numbers 57-71, lanthanum through lutetium) and is always present with the lanthanides in rare earth ores. Yttrium and the lanthanide holmium are particularly close chemical and physical analogues and are referred to as geochemical twins because they typically show little fractionation in geological material. Extensive measurements on rocks, soils, and meteorites indicate that the Y/Ho mass concentration ratio rarely falls far from the “chondritic” or “solar system” ratio of ~26. Our paper presents a new biokinetic model for yttrium in adult humansmore » and examines whether yttrium and holmium may be biological as well as geochemical twins. Collected data on yttrium and holmium in plants and human tissues do not allow precise derivations of Y/Ho concentration ratios but with occasional exceptions yield ratios that are reasonably consistent with chondritic values. Predictions of the time-dependent behavior of yttrium in adult humans based on the yttrium model presented here closely approximate predictions of the behavior of holmium based on a previously developed model for holmium. We know that yttrium and holmium are close biological analogues, but the available comparative data are too limited and imprecise to reveal whether there are any significant differences in their biological behavior.« less

Magnetic Doppler imaging of the chemically peculiar star HD 125248

NASA Astrophysics Data System (ADS)

Rusomarov, N.; Kochukhov, O.; Ryabchikova, T.; Ilyin, I.

2016-04-01

Context. Intermediate-mass, chemically peculiar stars with strong magnetic fields provide an excellent opportunity to study the topology of their surface magnetic fields and the interplay between magnetic geometries and abundance inhomogeneities in the atmospheres of these stars. Aims: We reconstruct detailed maps of the surface magnetic field and abundance distributions for the magnetic Ap star HD 125248. Methods: We performed the analysis based on phase-resolved, four Stokes parameter spectropolarimetric observations obtained with the HARPSpol instrument. These data were interpreted with the help of magnetic Doppler imaging techniques and model atmospheres taking the effects of strong magnetic fields and nonsolar chemical composition into account. Results: We improved the atmospheric parameters of the star, Teff = 9850 ± 250 K and log g = 4.05 ± 0.10. We performed detailed abundance analysis, which confirmed that HD 125248 has abundances typical of other Ap stars, and discovered significant vertical stratification effects for the Fe II and Cr II ions. We computed LSD Stokes profiles using several line masks corresponding to Fe-peak and rare earth elements, and studied their behavior with rotational phase. Combining previous longitudinal field measurements with our own observations, we improved the rotational period of the star Prot = 9.29558 ± 0.00006 d. Magnetic Doppler imaging of HD 125248 showed that its magnetic field is mostly poloidal and quasi-dipolar with two large spots of different polarity and field strength. The chemical maps of Fe, Cr, Ce, Nd, Gd, and Ti show abundance contrasts of 0.9-3.5 dex. Among these elements, the Fe abundance map does not show high-contrast features. Cr is overabundant around the negative magnetic pole and has 3.5 dex abundance range. The rare earth elements and Ti are overabundant near the positive magnetic pole. Conclusions: The magnetic field of HD 125248 has strong deviations from the classical oblique dipole field geometry. A comparison of the magnetic field topology of HD 125248 with the results derived for other stars using four Stokes magnetic Doppler imaging suggests evidence that the field topology becomes simpler with increasing age. The abundance maps show weak correlation with magnetic field geometry, but they do not agree with the theoretical atomic diffusion calculations, which predict element accumulation in the horizontal field regions. Based on observations collected at the European Southern Observatory, Chile (ESO programs 088.D-0066, 090.D-0256).

Regulatory processes of hunger motivated behavior.

PubMed

Lénárd, L; Karádi, Z

2012-01-01

While food intake and body weight are under homeostatic regulation, eating is a highly motivated and reinforced behavior that induces feelings of gratification and pleasure. The chemical senses (taste and odor) and their evaluation are essential to these functions. Brainstem and limbic glucose-monitoring (GM) neurons receiving neurochemical information from the periphery and from the local brain milieu are important controlling hunger motivation, and brain gut peptides have a modulatory role on this function. The hypothalamic and limbic forebrain areas are responsible for evaluation of reward quality and related emotions. They are innervated by the mesolimbic dopaminergic system (MLDS) and majority of GM neurons are also influenced by dopamine. Via dopamine release, the MLDS plays an essential role in rewarding-reinforcing processes of feeding and addiction. The GM network and the MLDS in the limbic system represent essential elements in the neural substrate of motivation.

Time-Dependent Behavior of Reinforced Polymer Concrete Columns under Eccentric Axial Loading

PubMed Central

Berardi, Valentino Paolo; Mancusi, Geminiano

2012-01-01

Polymer concretes (PCs) represent a promising alternative to traditional cementitious materials in the field of new construction. In fact, PCs exhibit high compressive strength and ultimate compressive strain values, as well as good chemical resistance. Within the context of these benefits, this paper presents a study on the time-dependent behavior of polymer concrete columns reinforced with different bar types using a mechanical model recently developed by the authors. Balanced internal reinforcements are considered (i.e., two bars at both the top and bottom of the cross-section). The investigation highlights relevant stress and strain variations over time and, consequently, the emergence of a significant decrease in concrete’s stiffness and strength over time. Therefore, the results indicate that deferred effects due to viscous flow may significantly affect the reliability of reinforced polymer concrete elements over time.

Long-lasting hydrophilicity on nanostructured Si-incorporated diamond-like carbon films.

PubMed

Yi, Jin Woo; Moon, Myoung-Woon; Ahmed, Sk Faruque; Kim, Haeri; Cha, Tae-Gon; Kim, Ho-Young; Kim, Seock-Sam; Lee, Kwang-Ryeol

2010-11-16

We investigated the long-lasting hydrophilic behavior of a Si-incorporated diamond-like carbon (Si-DLC) film by varying the Si fraction in DLC matrix through oxygen and nitrogen plasma surface treatments. The wetting behavior of the water droplets on the pure DLC and Si-DLC with the nitrogen or oxygen plasma treatment revealed that the Si element in the oxygen-plasma-treated Si-DLC films played a major role in maintaining a hydrophilic wetting angle of <10° for 20 days in ambient air. The nanostructured patterns with a roughness of ∼10 nm evolved because of the selective etching of the carbon matrix by the oxygen plasma in the Si-DLC film, where the chemical component of the Si-Ox bond was enriched on the top of the nanopatterns and remained for over 20 days.

Microstructure evolution and tribological properties of acrylonitrile-butadiene rubber surface modified by atmospheric plasma treatment

NASA Astrophysics Data System (ADS)

Shen, Ming-xue; Zhang, Zhao-xiang; Peng, Xu-dong; Lin, Xiu-zhou

2017-09-01

For the purpose of prolonging the service life for rubber sealing elements, the frictional behavior of acrylonitrile-butadiene rubber (NBR) surface by dielectric barrier discharge plasma treatments was investigated in this paper. Surface microstructure and chemical composition were measured by atomic force microscopy, field-emission scanning electron microscopy, and X-ray photoelectron spectroscopy, respectively. Water contact angles of the modified rubber surface were also measured to evaluate the correlation between surface wettability and tribological properties. The results show that plasma treatments can improve the properties of the NBR against friction and wear effectively, the surface microstructure and roughness of plasma-modified NBR surface had an important influence on the surface tribological behavior, and the wear depth first decreased and then increased along with the change of plasma treatment time. It was found that the wettability of the modified surface was gradually improved, which was mainly due to the change of the chemical composition after the treatment. This study suggests that the plasma treatment could effectively improve the tribological properties of the NBR surface, and also provides information for developing wear-resistant NBR for industrial applications.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Takeshita, Kenji

A mathematical model to predict the extraction behavior of metal ion between a polymer gel and an aqueous solution was proposed. It consists of the Flory-Huggins formula for evaluating thermodynamically the physico-chemical properties of polymer gel, the modified Stokes-Einstein equation to evaluate the mass transfer rate of metal ion into polymer gel and the equation to evaluate the extraction equilibrium. The extraction of lanthanide elements, Nd(III), Sm(III) and Gd(III), from an aqueous solution containing nitrate ion was carried out by the use of SDB (styrene-divinylbenzene copolymer) gel swollen with a bidentate organophosphorus compound, CMP (dihexyl-N,N-diethylcarbamoylmethylpohosphonate). The binary extraction and themore » effect of the crosslinking degree of SDB gel on the extraction rate were examined. These experimental results were in agreement with the predictions calculated by the proposed model. It was confirmed that the extraction behavior of lanthanide ions into the SDB gel was predicted accurately, when the physico-chemical properties of SDB gel, such as the affinity between SDB and CMP ({chi}) and the crosslinking degree ({nu}{sub e}), and a coefficient defined in the modified Stokes-Einstein equation (K{sub 0}) were known. This model is available as a tool to design an extraction chromatographic process using polymer gel.« less

Improved Strength and Toughness of Carbon Woven Fabric Composites with Functionalized MWCNTs

PubMed Central

Soliman, Eslam; Kandil, Usama; Reda Taha, Mahmoud

2014-01-01

This investigation examines the role of carboxyl functionalized multi-walled carbon nanotubes (COOH-MWCNTs) in the on- and off-axis flexure and the shear responses of thin carbon woven fabric composite plates. The chemically functionalized COOH-MWCNTs were used to fabricate epoxy nanocomposites and, subsequently, carbon woven fabric plates to be tested on flexure and shear. In addition to the neat epoxy, three loadings of COOH-MWCNTs were examined: 0.5 wt%, 1.0 wt% and 1.5 wt% of epoxy. While no significant statistical difference in the flexure response of the on-axis specimens was observed, significant increases in the flexure strength, modulus and toughness of the off-axis specimens were observed. The average increase in flexure strength and flexure modulus with the addition of 1.5 wt% COOH-MWCNTs improved by 28% and 19%, respectively. Finite element modeling is used to demonstrate fiber domination in on-axis flexure behavior and matrix domination in off-axis flexure behavior. Furthermore, the 1.5 wt% COOH-MWCNTs increased the toughness of carbon woven composites tested on shear by 33%. Microstructural investigation using Fourier Transform Infrared Spectroscopy (FTIR) proves the existence of chemical bonds between the COOH-MWCNTs and the epoxy matrix. PMID:28788698

In vitro testing of curcumin based composites coatings as antitumoral systems against osteosarcoma cells

NASA Astrophysics Data System (ADS)

Tirca, I.; Mitran, V.; Marascu, V.; Brajnicov, S.; Ion, V.; Stokker-Cheregi, F.; Popovici, I. A.; Cimpean, A.; Dinca, V.; Dinescu, M.

2017-12-01

In this work, we propose a new design for biodegradable composite coatings obtained by laser methods, which are aimed at evaluating the effects of active antitumoral elements on osteosarcoma cells. Our approach relies on embedding curcumin, which is a natural polyphenol having antitumoral properties, within biodegradable copolymer coatings (i.e. polyvinyl alcohol-polyethylene glycol - PVA-PEG) by using matrix assisted pulsed laser evaporation (MAPLE). The structural and morphological characteristics of the coatings were tailored by using different solvents (water, ethanol, benzene, dimethylsufoxide) as deposition matrix. The morphological characteristics of the resulting films were investigated by atomic force microscopy (AFM), whereas their chemical composition was characterized by Fourier transform infrared spectroscopy (FTIR). These characteristics were correlated with the degradation behavior by using ellipsometry (SE) and AFM measurements data. The in vitro study of the MG-63 osteosarcoma cell behavior indicates that the developed hybrid coatings significantly decreased osteosarcoma cell viability and proliferation potential. The physico-chemical characteristics of the thin films, along with the preliminary in vitro analyses, suggest that our developed polymeric hybrid coatings represent an efficient way to tackle the design of antitumoral surfaces, with applications in biomedicine.

Highly sensitive selectively coated photonic crystal fiber-based plasmonic sensor.

PubMed

Rifat, Ahmmed A; Haider, Firoz; Ahmed, Rajib; Mahdiraji, Ghafour Amouzad; Mahamd Adikan, F R; Miroshnichenko, Andrey E

2018-02-15

Highly sensitive and miniaturized sensors are highly desirable for real-time analyte/sample detection. In this Letter, we propose a highly sensitive plasmonic sensing scheme with the miniaturized photonic crystal fiber (PCF) attributes. A large cavity is introduced in the first ring of the PCFs for the efficient field excitation of the surface plasmon polariton mode and proficient infiltration of the sensing elements. Due to the irregular air-hole diameter in the first ring, the cavity exhibits the birefringence behavior which enhances the sensing performance. The novel plasmonic material gold has been used considering the chemical stability in an aqueous environment. The guiding properties and the effects of the sensing performance with different parameters have been investigated by the finite element method, and the proposed PCFs have been fabricated using the stack-and-draw fiber drawing method. The proposed sensor performance was investigated based on the wavelength and amplitude sensing techniques and shows the maximum sensitivities of 11,000 nm/RIU and 1,420  RIU -1 , respectively. It also shows the maximum sensor resolutions of 9.1×10 -6 and 7×10 -6   RIU for the wavelength and amplitude sensing schemes, respectively, and the maximum figure of merits of 407. Furthermore, the proposed sensor is able to detect the analyte refractive indices in the range of 1.33-1.42; as a result, it will find the possible applications in the medical diagnostics, biomolecules, organic chemical, and chemical analyte detection.

Some General Laws of Chemical Elements Composition Dynamics in the Hydrosphere

NASA Astrophysics Data System (ADS)

Korzh, V.

2012-12-01

The biophysical oceanic composition is a result of substance migration and transformation on river-sea and ocean- atmosphere boundaries. Chemical composition of oceanic water is a fundamental multi-dimensional constant for our planet. Detailed studies revealed three types of chemical element distribution in the ocean: 1) Conservative: concentration normalized to salinity is constant in space and time; 2) Nutrient-type: element concentration in the surface waters decreases due to the biosphere consumption; and 3) Litho-generative: complex character of distribution of elements, which enter the ocean with the river runoff and interred almost entirely in sediments (Fig. 1). The correlation between the chemical compositions of the river and oceanic water is high (r = 0.94). We conclude that biogeochemical features of each element are determined by the relationship between its average concentration in the ocean and the intensity of its migration through hydrosphere boundary zones. In Fig.1 we show intensities of global migration and average concentrations in the ocean in the coordinates lgC - lg τ, where C is an average element concentration and τ is its residual time in the ocean. Fig. 1 shows a relationship between three main geochemical parameters of the dissolved forms of chemical elements in the hydrosphere: 1) average concentration in the ocean, 2) average concentration in the river runoff and 3) the type of distribution in oceanic water. Using knowledge of two of these parameters, it allows gaining theoretical knowledge of the third. The System covers all chemical elements for the entire range of observed concentrations. It even allows to predict the values of the annual river transport of dissolved Be, C, N, Ge, Tl, Re, to refine such estimates for P, V, Zn, Br, I, and to determine the character of distribution in the ocean for Au and U. Furthermore, the System allowed to estimate natural (unaffected by anthropogenic influence) mean concentrations of elements in the river runoff and use them as ecological reference data. Finally, due to the long response time of the ocean, the mean concentrations of elements and patterns of their distribution in the ocean can be used to determine pre-technogenic concentrations of elements in the river runoff. An example of such studies for the Northern Eurasia Arctic Rivers will be presented at the conference. References Korzh 1974: J. de Recher. Atmos, 8, 653-660. Korzh 2008: J. Ecol., 15, 13-21. Korzh 2012: Water: Chem. & Ecol., No. 1, 56-62; Fig.1. The System of chemical elements distribution in the hydrosphere. Types of distribution in the ocean: 1) conservative; 2) nutrient-type; 3) litho-generative.

PLUTONIUM UPTAKE AND BEHAVIOR IN PLANTS OF THE DESERT SOUTHWEST: A PRELIMINARY ASSESSMENT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Caldwell, E.; Duff, M.; Ferguson, C.

2011-03-01

Eight species of desert vegetation and associated soils were collected from the Nevada National Security Site (N2S2) and analyzed for 238Pu and 239+240Pu concentrations. Amongst the plant species sampled were: atmospheric elemental accumulators (moss and lichen), the very slow growing, long-lived creosote bush and the rapidly growing, short-lived cheatgrass brome. The diversity of growth strategies provided insight into the geochemical behavior and bio-availability of Pu at the N2S2. The highest concentrations of Pu were measured in the onion moss (24.27 Bq kg-1 238Pu and 52.78 Bq kg-1 239+240Pu) followed by the rimmed navel lichen (8.18 Bq kg-1 and 18.4 Bqmore » kg-1 respectively), pointing to the importance of eolian transport of Pu. Brome and desert globemallow accumulated between 3 and 9 times higher concentrations of Pu than creosote and sage brush species. These results support the importance of species specific elemental accumulation strategies rather than exposure duration as the dominant variable influencing Pu concentrations in these plants. Total vegetation elemental concentrations of Ce, Fe, Al, Sm and others were also analyzed. Strong correlations were observed between Fe and Pu. This supports the conclusion that Pu was accumulated as a consequence of the active accumulation of Fe and other plant required nutrients. Cerium and Pu are considered to be chemical analogs. Strong correlations observed in plants support the conclusion that these elements displayed similar geochemical behavior in the environment as it related to the biochemical uptake process of vegetation. Soils were also sampled in association with vegetation samples. This allowed for the calculation of a concentration ratio (CR). The CR values for Pu in plants were highly influenced by the heterogeneity of Pu distribution among sites. Results from the naturally occurring elements of concern were more evenly distributed between sample sites. This allowed for the development of a pattern of plant species that accumulated Ce, Sm, Fe and Al. The highest accumulators of these elements were onion moss, lichen flowed by brome. The lowest accumulators were creosote bush and fourwing saltbush. This ranked order corresponds to plant accumulations of Pu.« less

Investigation of Embedded Si/C System Exposed to a Hybrid Reaction of Centrifugal-Assisted Thermite Method

PubMed Central

Mahmoodian, Reza; Yahya, Rosiyah; Dabbagh, Ali; Hamdi, Mohd; Hassan, Mohsen A.

2015-01-01

A novel method is proposed to study the behavior and phase formation of a Si+C compacted pellet under centrifugal acceleration in a hybrid reaction. Si+C as elemental mixture in the form of a pellet is embedded in a centrifugal tube. The pellet assembly and tube are exposed to the sudden thermal energy of a thermite reaction resulted in a hybrid reaction. The hybrid reaction of thermite and Si+C produced unique phases. X-ray diffraction pattern (XRD) as well as microstructural and elemental analyses are then investigated. XRD pattern showed formation of materials with possible electronic and magnetic properties. The cooling rate and the molten particle viscosity mathematical model of the process are meant to assist in understanding the physical and chemical phenomena took place during and after reaction. The results analysis revealed that up to 85% of materials converted into secondary products as ceramics-matrix composite. PMID:26641651

M3FT-15OR0202212: SUBMIT SUMMARY REPORT ON THERMODYNAMIC EXPERIMENT AND MODELING

DOE Office of Scientific and Technical Information (OSTI.GOV)

McMurray, Jake W.; Brese, Robert G.; Silva, Chinthaka M.

2015-09-01

Modeling the behavior of nuclear fuel with a physics-based approach uses thermodynamics for key inputs such as chemical potentials and thermal properties for phase transformation, microstructure evolution, and continuum transport simulations. Many of the lanthanide (Ln) elements and Y are high-yield fission products. The U-Y-O and U-Ln-O ternaries are therefore key subsystems of multi-component high-burnup fuel. These elements dissolve in the dominant urania fluorite phase affecting many of its properties. This work reports on an effort to assess the thermodynamics of the U-Pr-O and U-Y-O systems using the CALPHAD (CALculation of PHase Diagrams) method. The models developed within this frameworkmore » are capable of being combined and extended to include additional actinides and fission products allowing calculation of the phase equilibria, thermochemical and material properties of multicomponent fuel with burnup.« less

Arsenic: A Review of the Element's Toxicity, Plant Interactions, and Potential Methods of Remediation.

PubMed

Hettick, Bryan E; Cañas-Carrell, Jaclyn E; French, Amanda D; Klein, David M

2015-08-19

Arsenic is a naturally occurring element with a long history of toxicity. Sites of contamination are found worldwide as a result of both natural processes and anthropogenic activities. The broad scope of arsenic toxicity to humans and its unique interaction with the environment have led to extensive research into its physicochemical properties and toxic behavior in biological systems. The purpose of this review is to compile the results of recent studies concerning the metalloid and consider the chemical and physical properties of arsenic in the broad context of human toxicity and phytoremediation. Areas of focus include arsenic's mechanisms of human toxicity, interaction with plant systems, potential methods of remediation, and protocols for the determination of metals in experimentation. This assessment of the literature indicates that controlling contamination of water sources and plants through effective remediation and management is essential to successfully addressing the problems of arsenic toxicity and contamination.

Investigation of Embedded Si/C System Exposed to a Hybrid Reaction of Centrifugal-Assisted Thermite Method.

PubMed

Mahmoodian, Reza; Yahya, Rosiyah; Dabbagh, Ali; Hamdi, Mohd; Hassan, Mohsen A

2015-01-01

A novel method is proposed to study the behavior and phase formation of a Si+C compacted pellet under centrifugal acceleration in a hybrid reaction. Si+C as elemental mixture in the form of a pellet is embedded in a centrifugal tube. The pellet assembly and tube are exposed to the sudden thermal energy of a thermite reaction resulted in a hybrid reaction. The hybrid reaction of thermite and Si+C produced unique phases. X-ray diffraction pattern (XRD) as well as microstructural and elemental analyses are then investigated. XRD pattern showed formation of materials with possible electronic and magnetic properties. The cooling rate and the molten particle viscosity mathematical model of the process are meant to assist in understanding the physical and chemical phenomena took place during and after reaction. The results analysis revealed that up to 85% of materials converted into secondary products as ceramics-matrix composite.

Bioaccessibility of metals in alloys: Evaluation of three surrogate biofluids

PubMed Central

Hillwalker, Wendy E.; Anderson, Kim A.

2014-01-01

Bioaccessibility in vitro tests measure the solubility of materials in surrogate biofluids. However, the lack of uniform methods and the effects of variable test parameters on material solubility limit interpretation. One aim of this study was to measure and compare bioaccessibility of selected economically important alloys and metals in surrogate physiologically based biofluids representing oral, inhalation and dermal exposures. A second aim was to experimentally test different biofluid formulations and residence times in vitro. A third aim was evaluation of dissolution behavior of alloys with in vitro lung and dermal biofluid surrogates. This study evaluated the bioaccessibility of sixteen elements in six alloys and 3 elemental/metal powders. We found that the alloys/metals, the chemical properties of the surrogate fluid, and residence time all had major impacts on metal solubility. The large variability of bioaccessibility indicates the relevancy of assessing alloys as toxicologically distinct relative to individual metals. PMID:24212234

An in situ approach to study trace element partitioning in the laser heated diamond anvil cell

DOE Office of Scientific and Technical Information (OSTI.GOV)

Petitgirard, S.; Mezouar, M.; Borchert, M.

2012-01-15

Data on partitioning behavior of elements between different phases at in situ conditions are crucial for the understanding of element mobility especially for geochemical studies. Here, we present results of in situ partitioning of trace elements (Zr, Pd, and Ru) between silicate and iron melts, up to 50 GPa and 4200 K, using a modified laser heated diamond anvil cell (DAC). This new experimental set up allows simultaneous collection of x-ray fluorescence (XRF) and x-ray diffraction (XRD) data as a function of time using the high pressure beamline ID27 (ESRF, France). The technique enables the simultaneous detection of sample meltingmore » based to the appearance of diffuse scattering in the XRD pattern, characteristic of the structure factor of liquids, and measurements of elemental partitioning of the sample using XRF, before, during and after laser heating in the DAC. We were able to detect elements concentrations as low as a few ppm level (2-5 ppm) on standard solutions. In situ measurements are complimented by mapping of the chemical partitions of the trace elements after laser heating on the quenched samples to constrain the partitioning data. Our first results indicate a strong partitioning of Pd and Ru into the metallic phase, while Zr remains clearly incompatible with iron. This novel approach extends the pressure and temperature range of partitioning experiments derived from quenched samples from the large volume presses and could bring new insight to the early history of Earth.« less

Combined effects of different heat treatments and Cu element on transformation behavior of NiTi orthodontic wires.

PubMed

Seyyed Aghamiri, S M; Ahmadabadi, M Nili; Raygan, Sh

2011-04-01

The shape memory nickel-titanium alloy has been applied in many fields due to its unique thermal and mechanical performance. One of the successful applications of NiTi wires is in orthodontics because of its good characteristics such as low stiffness, high spring back, high stored energy, biocompatibility, superelasticity and shape memory effect. The mechanical properties of wires are paid special attention which results in achieving continuous optimal forces and eventually causing rapid tooth movement without any damage. The behavior of the alloy can be controlled by chemical composition and thermo-mechanical treatment during the manufacturing process. In this study two kinds of commercial superelastic NiTi archwires of 0.41 mm diameter were investigated: Copper NiTi and Highland Metal. The chemical analysis of both wires was estimated by energy dispersive spectroscopy (EDS). It was showed that Copper NiTi wire contained copper and chromium. The two types of wires were exposed to different heat treatment conditions at 400 and 500 °C for 10 and 60 min to compare the behavior of the wires at aged and as-received conditions. Phase transformation temperatures clarified by differential scanning calorimetry (DSC) showed B2 <--> R <--> B19 transformation in Highland Metal wire and B2 <--> B19(') transformation in Copper NiTi wire. Three point bending (TPB) tests in the certain designed fixture were performed at 37 °C to evaluate the mechanical behavior of the wires. The experimental results revealed the superelastic behavior of the Highland Metal wire after 60 min ageing at 400 and 500 °C and the plastic deformation of the Copper NiTi wire after annealing due to the effect of copper in the alloy composition. Copyright © 2010 Elsevier Ltd. All rights reserved.

Chemical Sensing Using Fiber Cavity Ring-Down Spectroscopy

PubMed Central

Waechter, Helen; Litman, Jessica; Cheung, Adrienne H.; Barnes, Jack A.; Loock, Hans-Peter

2010-01-01

Waveguide-based cavity ring-down spectroscopy (CRD) can be used for quantitative measurements of chemical concentrations in small amounts of liquid, in gases or in films. The change in ring-down time can be correlated to analyte concentration when using fiber optic sensing elements that change their attenuation in dependence of either sample absorption or refractive index. Two types of fiber cavities, i.e., fiber loops and fiber strands containing reflective elements, are distinguished. Both types of cavities were coupled to a variety of chemical sensor elements, which are discussed and compared. PMID:22294895

Mixed formulation for seismic analysis of composite steel-concrete frame structures

NASA Astrophysics Data System (ADS)

Ayoub, Ashraf Salah Eldin

This study presents a new finite element model for the nonlinear analysis of structures made up of steel and concrete under monotonic and cyclic loads. The new formulation is based on a two-field mixed formulation. In the formulation, both forces and deformations are simultaneously approximated within the element through independent interpolation functions. The main advantages of the model is the accuracy in global and local response with very few elements while maintaining rapid numerical convergence and robustness even under severe cyclic loading. Overall four elements were developed based on the new formulation: an element that describes the behavior of anchored reinforcing bars, an element that describes the behavior of composite steel-concrete beams with deformable shear connectors, an element that describes the behavior of reinforced concrete beam-columns with bond-slip, and an element that describes the behavior of pretensioned or posttensioned, bonded or unbonded prestressed concrete structures. The models use fiber discretization of beam sections to describe nonlinear material response. The transfer of forces between steel and concrete is described with bond elements. Bond elements are modeled with distributed spring elements. The non-linear behavior of the composite element derives entirely from the constitutive laws of the steel, concrete and bond elements. Two additional elements are used for the prestressed concrete models, a friction element that models the effect of friction between the tendon and the duct during the posttensioning operation, and an anchorage element that describes the behavior of the prestressing tendon anchorage in posttensioned structures. Two algorithms for the numerical implementation of the new proposed model are presented; an algorithm that enforces stress continuity at element boundaries, and an algorithm in which stress continuity is relaxed locally inside the element. Stability of both algorithms is discussed. Comparison with standard displacement based models and earlier flexibility based models is presented through numerical studies. The studies prove the superiority of the mixed model over both displacement and flexibility models. Correlation studies of the proposed model with experimental results of structural specimens are conducted. The studies show the accuracy of the model and its numerical robustness even under severe cyclic loading conditions.

Discrete meso-element simulation of chemical reactions in shear bands

NASA Astrophysics Data System (ADS)

Tamura, S.; Horie, Y.

1998-07-01

A meso-dynamic simulation technique is used to investigate the chemical reactions in high speed shearing of reactive porous mixtures. The reaction speed is assumed to be a function of temperature, pressure and mixing of materials. To gain a theoretical insight into the experiments reported by Nesterenko et al., a parametric study of material flow and local temperature was carried out using a Nb and Si mixture. In the model calculation, a heterogeneous shear region of 5 μm width, consisting of alternating layers of Nb and Si, was created first in a mixture and then sheared at the rate of 8.0×107s-1. Results show that the material flow is mostly homogeneous, but contains a local agglomeration and circulatory flow. This behavior accelerates mass mixing and causes a significant temperature increase. To evaluate the mixing of material, average minimum distance of materials separation was calculated. Voids effect were also investigated.

Micropatterned arrays of porous silicon: toward sensory biointerfaces.

PubMed

Flavel, Benjamin S; Sweetman, Martin J; Shearer, Cameron J; Shapter, Joseph G; Voelcker, Nicolas H

2011-07-01

We describe the fabrication of arrays of porous silicon spots by means of photolithography where a positive photoresist serves as a mask during the anodization process. In particular, photoluminescent arrays and porous silicon spots suitable for further chemical modification and the attachment of human cells were created. The produced arrays of porous silicon were chemically modified by means of a thermal hydrosilylation reaction that facilitated immobilization of the fluorescent dye lissamine, and alternatively, the cell adhesion peptide arginine-glycine-aspartic acid-serine. The latter modification enabled the selective attachment of human lens epithelial cells on the peptide functionalized regions of the patterns. This type of surface patterning, using etched porous silicon arrays functionalized with biological recognition elements, presents a new format of interfacing porous silicon with mammalian cells. Porous silicon arrays with photoluminescent properties produced by this patterning strategy also have potential applications as platforms for in situ monitoring of cell behavior.

Radial patterns of tree-ring chemical element concentration in two Appalachian hardwood stands

Treesearch

D.R. Dewalle; B.R. Swistock; W.E. Sharpe

1991-01-01

Radial patterns in tree-ring chemical element concentration in red oak (Quercus rubra L.) and black (Prunus serotina Ehrh.) were analyzed to infer past environmental changes at two mature Appalachian forest sites.

CHEMICAL ANALYSIS METHODS FOR ATMOSPHERIC AEROSOL COMPONENTS

EPA Science Inventory

This chapter surveys the analytical techniques used to determine the concentrations of aerosol mass and its chemical components. The techniques surveyed include mass, major ions (sulfate, nitrate, ammonium), organic carbon, elemental carbon, and trace elements. As reported in...

A conceptual framework for effectively anticipating water-quality changes resulting from changes in agricultural activities

USGS Publications Warehouse

Capel, Paul D.; Wolock, David M.; Coupe, Richard H.; Roth, Jason L.

2018-01-10

Agricultural activities can affect water quality and the health of aquatic ecosystems; many water-quality issues originate with the movement of water, agricultural chemicals, and eroded soil from agricultural areas to streams and groundwater. Most agricultural activities are designed to sustain or increase crop production, while some are designed to protect soil and water resources. Numerous soil- and water-protection practices are designed to reduce the volume and velocity of runoff and increase infiltration. This report presents a conceptual framework that combines generalized concepts on the movement of water, the environmental behavior of chemicals and eroded soil, and the designed functions of various agricultural activities, as they relate to hydrology, to create attainable expectations for the protection of—with the goal of improving—water quality through changes in an agricultural activity.The framework presented uses two types of decision trees to guide decision making toward attainable expectations regarding the effectiveness of changing agricultural activities to protect and improve water quality in streams. One decision tree organizes decision making by considering the hydrologic setting and chemical behaviors, largely at the field scale. This decision tree can help determine which agricultural activities could effectively protect and improve water quality in a stream from the movement of chemicals, or sediment, from a field. The second decision tree is a chemical fate accounting tree. This decision tree helps set attainable expectations for the permanent removal of sediment, elements, and organic chemicals—such as herbicides and insecticides—through trapping or conservation tillage practices. Collectively, this conceptual framework consolidates diverse hydrologic settings, chemicals, and agricultural activities into a single, broad context that can be used to set attainable expectations for agricultural activities. This framework also enables better decision making for future agricultural activities as a means to reduce current, and prevent new, water-quality issues.

On track for success: an innovative behavioral science curriculum model.

PubMed

Freedy, John R; Carek, Peter J; Dickerson, Lori M; Mallin, Robert M

2013-01-01

This article describes the behavioral science curriculum currently in place at the Trident/MUSC Family Medicine Residency Program. The Trident/MUSC Program is a 10-10-10 community-based, university-affiliated program in Charleston, South Carolina. Over the years, the Trident/MUSC residency program has graduated over 400 Family Medicine physicians. The current behavioral science curriculum consists of both required core elements (didactic lectures, clinical observation, Balint groups, and Resident Grand Rounds) as well as optional elements (longitudinal patient care experiences, elective rotations, behavioral science editorial experience, and scholars project with a behavioral science focus). All Trident/MUSC residents complete core behavioral science curriculum elements and are free to participate in none, some, or all of the optional behavioral science curriculum elements. This flexibility allows resident physicians to tailor the educational program in a manner to meet individual educational needs. The behavioral science curriculum is based upon faculty interpretation of existing "best practice" guidelines (Residency Review Committee-Family Medicine and AAFP). This article provides sufficient curriculum detail to allow the interested reader the opportunity to adapt elements of the behavioral science curriculum to other residency training programs. While this behavioral science track system is currently in an early stage of implementation, the article discusses track advantages as well as future plans to evaluate various aspects of this innovative educational approach.

Tin in granitic melts: The role of melting temperature and protolith composition

NASA Astrophysics Data System (ADS)

Wolf, Mathias; Romer, Rolf L.; Franz, Leander; López-Moro, Francisco Javier

2018-06-01

Granite bound tin mineralization typically is seen as the result of extreme magmatic fractionation and late exsolution of magmatic fluids. Mineralization, however, also could be obtained at considerably less fractionation if initial melts already had enhanced Sn contents. We present chemical data and results from phase diagram modeling that illustrate the dominant roles of protolith composition, melting conditions, and melt extraction/evolution for the distribution of Sn between melt and restite and, thus, the Sn content of melts. We compare the element partitioning between leucosome and restite of low-temperature and high-temperature migmatites. During low-temperature melting, trace elements partition preferentially into the restite with the possible exception of Sr, Cd, Bi, and Pb, that may be enriched in the melt. In high-temperature melts, Ga, Y, Cd, Sn, REE, Pb, Bi, and U partition preferentially into the melt whereas Sc, V, Cr, Co, Ni, Mo, and Ba stay in the restite. This contrasting behavior is attributed to the stability of trace element sequestering minerals during melt generation. In particular muscovite, biotite, titanite, and rutile act as host phases for Sn and, therefore prevent Sn enrichment in the melt as long as they are stable phases in the restite. As protolith composition controls both the mineral assemblage and modal contents of the various minerals, protolith composition eventually also controls the fertility of a rock during anatexis, restite mineralogy, and partitioning behavior of trace metals. If a particular trace element is sequestered in a phase that is stable during partial melting, the resulting melt is depleted in this element whereas the restite becomes enriched. Melt generation at high temperature may release Sn when Sn-hosts become unstable. If melt has not been lost before the breakdown of Sn-hosts, Sn contents in the melt will increase but never will be high. In contrast, if melt has been lost before the decomposition of Sn-hosts, the small volume of the high-temperature melt will not be diluted by low-temperature, low-Sn melts and, therefore, could have high Sn-contents. The combination of multiple melt extractions and Sn-mobilization at high temperature results in strong Sn enrichment in late, high-temperature melts. Metal enrichment during partial melting becomes particularly efficient, if the sedimentary protolith had experienced intense chemical alteration as the loss of Na and Ca together with a relative enrichment of K favors muscovite-rich metamorphic mineral assemblages that produce large amounts of melt during muscovite dehydration melting.

Origin of the biologically important elements.

PubMed

Trimble, V

1997-06-01

The chemical elements most widely distributed in terrestrial living creatures are the ones (apart from inert helium and neon) that are commonest in the Universe--hydrogen, oxygen, carbon, and nitrogen. A chemically different Universe would clearly have different biology, if any. We explore here the nuclear processes in stars, the early Universe, and elsewhere that have produced these common elements, and, while we are at it, also encounter the production of lithium, gold, uranium, and other elements of sociological, if not biological, importance. The relevant processes are, for the most part, well understood. Much less well understood is the overall history of chemical evolution of the Galaxy, from pure hydrogen and helium to the mix of elements we see today. One implication is that we cannot do a very good job of estimating how many stars and which ones might be orbited by habitable planets.

Dissection of neuronal gap junction circuits that regulate social behavior in Caenorhabditis elegans.

PubMed

Jang, Heeun; Levy, Sagi; Flavell, Steven W; Mende, Fanny; Latham, Richard; Zimmer, Manuel; Bargmann, Cornelia I

2017-02-14

A hub-and-spoke circuit of neurons connected by gap junctions controls aggregation behavior and related behavioral responses to oxygen, pheromones, and food in Caenorhabditis elegans The molecular composition of the gap junctions connecting RMG hub neurons with sensory spoke neurons is unknown. We show here that the innexin gene unc-9 is required in RMG hub neurons to drive aggregation and related behaviors, indicating that UNC-9-containing gap junctions mediate RMG signaling. To dissect the circuit in detail, we developed methods to inhibit unc-9 -based gap junctions with dominant-negative unc-1 transgenes. unc-1(dn) alters a stomatin-like protein that regulates unc-9 electrical signaling; its disruptive effects can be rescued by a constitutively active UNC-9::GFP protein, demonstrating specificity. Expression of unc-1(dn) in RMG hub neurons, ADL or ASK pheromone-sensing neurons, or URX oxygen-sensing neurons disrupts specific elements of aggregation-related behaviors. In ADL, unc-1(dn) has effects opposite to those of tetanus toxin light chain, separating the roles of ADL electrical and chemical synapses. These results reveal roles of gap junctions in a complex behavior at cellular resolution and provide a tool for similar exploration of other gap junction circuits.

Dissection of neuronal gap junction circuits that regulate social behavior in Caenorhabditis elegans

PubMed Central

Jang, Heeun; Levy, Sagi; Flavell, Steven W.; Mende, Fanny; Latham, Richard; Zimmer, Manuel; Bargmann, Cornelia I.

2017-01-01

A hub-and-spoke circuit of neurons connected by gap junctions controls aggregation behavior and related behavioral responses to oxygen, pheromones, and food in Caenorhabditis elegans. The molecular composition of the gap junctions connecting RMG hub neurons with sensory spoke neurons is unknown. We show here that the innexin gene unc-9 is required in RMG hub neurons to drive aggregation and related behaviors, indicating that UNC-9–containing gap junctions mediate RMG signaling. To dissect the circuit in detail, we developed methods to inhibit unc-9–based gap junctions with dominant-negative unc-1 transgenes. unc-1(dn) alters a stomatin-like protein that regulates unc-9 electrical signaling; its disruptive effects can be rescued by a constitutively active UNC-9::GFP protein, demonstrating specificity. Expression of unc-1(dn) in RMG hub neurons, ADL or ASK pheromone-sensing neurons, or URX oxygen-sensing neurons disrupts specific elements of aggregation-related behaviors. In ADL, unc-1(dn) has effects opposite to those of tetanus toxin light chain, separating the roles of ADL electrical and chemical synapses. These results reveal roles of gap junctions in a complex behavior at cellular resolution and provide a tool for similar exploration of other gap junction circuits. PMID:28143932

Iron Partitioning in Ferropericlase and Consequences for the Magma Ocean.

NASA Astrophysics Data System (ADS)

Braithwaite, J. W. H.; Stixrude, L. P.; Holmstrom, E.; Pinilla, C.

2016-12-01

The relative buoyancy of crystals and liquid is likely to exert a strong influence on the thermal and chemical evolution of the magma ocean. Theory indicates that liquids approach, but do not exceed the density of iso-chemical crystals in the deep mantle. The partitioning of heavy elements, such as Fe, is therefore likely to control whether crystals sink or float. While some experimental results exist, our knowledge of silicate liquid-crystal element partitioning is still limited in the deep mantle. We have developed a method for computing the Mg-Fe partitioning of Fe in such systems. We have focused initially on ferropericlase, as a relatively simple system where the buoyancy effects of Fe partitioning are likely to be large. The method is based on molecular dynamics driven by density functional theory (spin polarized, PBEsol+U). We compute the free energy of Mg for Fe substitution in simulations of liquid and B1 crystalline phases via adiabatic switching. We investigate the dependence of partitioning on pressure, temperature, and iron concentration. We find that the liquid is denser than the coexisting crystalline phase at all conditions studies. We also find that the high-spin to low-spin transition in the crystal and the liquid, have an important influence on partitioning behavior.

Brown rice and its component, γ-oryzanol, attenuate the preference for high-fat diet by decreasing hypothalamic endoplasmic reticulum stress in mice.

PubMed

Kozuka, Chisayo; Yabiku, Kouichi; Sunagawa, Sumito; Ueda, Rei; Taira, Shin-Ichiro; Ohshiro, Hiroyuki; Ikema, Tomomi; Yamakawa, Ken; Higa, Moritake; Tanaka, Hideaki; Takayama, Chitoshi; Matsushita, Masayuki; Oyadomari, Seiichi; Shimabukuro, Michio; Masuzaki, Hiroaki

2012-12-01

Brown rice is known to improve glucose intolerance and prevent the onset of diabetes. However, the underlying mechanisms remain obscure. In the current study, we investigated the effect of brown rice and its major component, γ-oryzanol (Orz), on feeding behavior and fuel homeostasis in mice. When mice were allowed free access to a brown rice-containing chow diet (CD) and a high-fat diet (HFD), they significantly preferred CD to HFD. To reduce hypothalamic endoplasmic reticulum (ER) stress on an HFD, mice were administered with 4-phenylbutyric acid, a chemical chaperone, which caused them to prefer the CD. Notably, oral administration of Orz, a mixture of major bioactive components in brown rice, also improved glucose intolerance and attenuated hypothalamic ER stress in mice fed the HFD. In murine primary neuronal cells, Orz attenuated the tunicamycin-induced ER stress. In luciferase reporter assays in human embryonic kidney 293 cells, Orz suppressed the activation of ER stress-responsive cis-acting elements and unfolded protein response element, suggesting that Orz acts as a chemical chaperone in viable cells. Collectively, the current study is the first demonstration that brown rice and Orz improve glucose metabolism, reduce hypothalamic ER stress, and, consequently, attenuate the preference for dietary fat in mice fed an HFD.

Tracking Radionuclide Fractionation in the First Atomic Explosion Using Stable Elements

DOE PAGES

Bonamici, Chloë E.; Hervig, Richard L.; Kinman, William S.

2017-08-25

Compositional analysis of postdetonation fallout is a tool for forensic identification of nuclear devices. However, the relationship between device composition and fallout composition is difficult to interpret because of the complex combination of physical mixing, nuclear reactions, and chemical fractionations that occur in the chaotic nuclear fireball. By using a combination of in situ microanalytical techniques (electron microprobe analysis and secondary ion mass spectrometry), we show that some heavy stable elements (Rb, Sr, Zr, Ba, Cs, Ba, La, Ce, Nd, Sm, Dy, Lu, U, Th) in glassy fallout from the first nuclear test, Trinity, are reliable chemical proxies for radionuclidesmore » generated during the explosion. Stable-element proxies show that radionuclides from the Trinity device were chemically, but not isotopically, fractionated by condensation. Moreover, stable-element proxies delineate chemical fractionation trends that can be used to connect present-day fallout composition to past fireball composition. Stable-element proxies therefore offer a novel approach for elucidating the phenomenology of the nuclear fireball as it relates to the formation of debris and the fixation of device materials within debris.« less

Tracking Radionuclide Fractionation in the First Atomic Explosion Using Stable Elements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bonamici, Chloë E.; Hervig, Richard L.; Kinman, William S.

Compositional analysis of postdetonation fallout is a tool for forensic identification of nuclear devices. However, the relationship between device composition and fallout composition is difficult to interpret because of the complex combination of physical mixing, nuclear reactions, and chemical fractionations that occur in the chaotic nuclear fireball. By using a combination of in situ microanalytical techniques (electron microprobe analysis and secondary ion mass spectrometry), we show that some heavy stable elements (Rb, Sr, Zr, Ba, Cs, Ba, La, Ce, Nd, Sm, Dy, Lu, U, Th) in glassy fallout from the first nuclear test, Trinity, are reliable chemical proxies for radionuclidesmore » generated during the explosion. Stable-element proxies show that radionuclides from the Trinity device were chemically, but not isotopically, fractionated by condensation. Moreover, stable-element proxies delineate chemical fractionation trends that can be used to connect present-day fallout composition to past fireball composition. Stable-element proxies therefore offer a novel approach for elucidating the phenomenology of the nuclear fireball as it relates to the formation of debris and the fixation of device materials within debris.« less

Tracking Radionuclide Fractionation in the First Atomic Explosion Using Stable Elements.

PubMed

Bonamici, Chloë E; Hervig, Richard L; Kinman, William S

2017-09-19

Compositional analysis of postdetonation fallout is a tool for forensic identification of nuclear devices. However, the relationship between device composition and fallout composition is difficult to interpret because of the complex combination of physical mixing, nuclear reactions, and chemical fractionations that occur in the chaotic nuclear fireball. Using a combination of in situ microanalytical techniques (electron microprobe analysis and secondary ion mass spectrometry), we show that some heavy stable elements (Rb, Sr, Zr, Ba, Cs, Ba, La, Ce, Nd, Sm, Dy, Lu, U, Th) in glassy fallout from the first nuclear test, Trinity, are reliable chemical proxies for radionuclides generated during the explosion. Stable-element proxies show that radionuclides from the Trinity device were chemically, but not isotopically, fractionated by condensation. Furthermore, stable-element proxies delineate chemical fractionation trends that can be used to connect present-day fallout composition to past fireball composition. Stable-element proxies therefore offer a novel approach for elucidating the phenomenology of the nuclear fireball as it relates to the formation of debris and the fixation of device materials within debris.

IUPAC Periodic Table of the Isotopes

USGS Publications Warehouse

Holden, N.E.; Coplen, T.B.; Böhlke, J.K.; Wieser, M.E.; Singleton, G.; Walczyk, T.; Yoneda, S.; Mahaffy, P.G.; Tarbox, L.V.

2011-01-01

For almost 150 years, the Periodic Table of the Elements has served as a guide to the world of elements by highlighting similarities and differences in atomic structure and chemical properties. To introduce students, teachers, and society to the existence and importance of isotopes of the chemical elements, an IUPAC Periodic Table of the Isotopes (IPTI) has been prepared and can be found as a supplement to this issue.

The average chemical composition of the lunar surface

NASA Technical Reports Server (NTRS)

Turkevich, A. L.

1973-01-01

The available analytical data from twelve locations on the moon are used to estimate the average amounts of the principal chemical elements (O, Na, Mg, Al, Si, Ca, Ti, and Fe) in the mare, the terra, and the average lunar surface regolith. These chemical elements comprise about 99% of the atoms on the lunar surface. The relatively small variability in the amounts of these elements at different mare (or terra) sites, and the evidence from the orbital measurements of Apollo 15 and 16, suggest that the lunar surface is much more homogeneous than the surface of the earth. The average chemical composition of the lunar surface may now be known as well as, if not better than, that of the solid part of the earth's surface.

Chemical composition of δ Scuti stars: 1. AO CVn, CP Boo, KW Aur

NASA Astrophysics Data System (ADS)

Galeev, A. I.; Ivanova, D. V.; Shimansky, V. V.; Bikmaev, I. F.

2012-11-01

We used high-resolution echelle spectra acquired with the 1.5-m Russian-Turkish Telescope to determine the fundamental atmospheric parameters and abundances of 30 chemical elements for three δ Scuti stars: AOCVn, CP Boo, and KWAur. The chemical compositions we find for these stars are similar to those for Am-star atmospheres, though some anomalies of up to 0.6-0.7 dex are observed for light and heavy elements. We consider the effect of the adopted stellar parameters (effective temperature, log g, microturbulent velocity) and the amplitude of pulsational variations on the derived elemental abundances.

Identifying Common Practice Elements to Improve Social, Emotional, and Behavioral Outcomes of Young Children in Early Childhood Classrooms.

PubMed

McLeod, Bryce D; Sutherland, Kevin S; Martinez, Ruben G; Conroy, Maureen A; Snyder, Patricia A; Southam-Gerow, Michael A

2017-02-01

Educators are increasingly being encouraged to implement evidence-based interventions and practices to address the social, emotional, and behavioral needs of young children who exhibit problem behavior in early childhood settings. Given the nature of social-emotional learning during the early childhood years and the lack of a common set of core evidence-based practices within the early childhood literature, selection of instructional practices that foster positive social, emotional, and behavioral outcomes for children in early childhood settings can be difficult. The purpose of this paper is to report findings from a study designed to identify common practice elements found in comprehensive intervention models (i.e., manualized interventions that include a number of components) or discrete practices (i.e., a specific behavior or action) designed to target social, emotional, and behavioral learning of young children who exhibit problem behavior. We conducted a systematic review of early childhood classroom interventions that had been evaluated in randomized group designs, quasi-experimental designs, and single-case experimental designs. A total of 49 published articles were identified, and an iterative process was used to identify common practice elements. The practice elements were subsequently reviewed by experts in social-emotional and behavioral interventions for young children. Twenty-four practice elements were identified and classified into content (the goal or general principle that guides a practice element) and delivery (the way in which a teacher provides instruction to the child) categories. We discuss implications that the identification of these practice elements found in the early childhood literature has for efforts to implement models and practices.

Effect of negative bias on TiAlSiN coating deposited on nitrided Zircaloy-4

NASA Astrophysics Data System (ADS)

Jun, Zhou; Zhendong, Feng; Xiangfang, Fan; Yanhong, Liu; Huanlin, Li

2018-01-01

TiAlSiN coatings were deposited on the nitrided Zircaloy-4 by multi-arc ion plating at -100 V, -200 V and -300 V. In this study, the high temperature oxidation behavior of coatings was tested by a box-type resistance furnace in air for 3 h at 800 °C; the macro-morphology of coatings was observed and analyzed by a zoom-stereo microscope; the micro-morphology of coatings was analyzed by a scanning electron microscopy (SEM), and the chemical elements of samples were analyzed by an energy dispersive spectroscopy(EDS); the adhesion strength of the coating to the substrate was measured by an automatic scratch tester; and the phases of coatings were analyzed by an X-ray diffractometer(XRD). Results show that the coating deposited at -100 V shows better high temperature oxidation resistance behavior, at the same time, Al elements contained in the coating is of the highest amount, meanwhile, the adhesion strength of the coating to the substrate is the highest, which is 33N. As the bias increases, high temperature oxidation resistance behavior of the coating weakens first and then increases, the amount of large particles on the surface of the coating increases first and then decreases whereas the density of the coating decreases first and then increases, and adhesion strength of the coating to the substrate increases first and then weakens. The coating's quality is relatively poor when the bias is -200 V.

Chemical resolution of Pu+ from U+ and Am+ using a band-pass reaction cell inductively coupled plasma mass spectrometer.

PubMed

Tanner, Scott D; Li, Chunsheng; Vais, Vladimir; Baranov, Vladimir I; Bandura, Dmitry R

2004-06-01

Determination of the concentration and distribution of the Pu and Am isotopes is hindered by the isobaric overlaps between the elements themselves and U, generally requiring time-consuming chemical separation of the elements. A method is described in which chemical resolution of the elemental ions is obtained through ion-molecule reactions in a reaction cell of an ICPMS instrument. The reactions of "natural" U(+), (242)Pu(+), and (243)Am(+) with ethylene, carbon dioxide, and nitric oxide are reported. Since the net sensitivities to the isotopes of an element are similar, chemical resolution is inferred when one isobaric element reacts rapidly with a given gas and the isobar (or in this instance surrogate isotope) is unreactive or slowly reactive. Chemical resolution of the m/z 238 isotopes of U and Pu can be obtained using ethylene as a reaction gas, but little improvement in the resolution of the m/z 239 isobars is obtained. However, high efficiency of reaction of U(+) and UH(+) with CO(2), and nonreaction of Pu(+), allows the sub-ppt determination of (239)Pu, (240)Pu, and (242)Pu (single ppt for (238)Pu) in the presence of 7 orders of magnitude excess U matrix without prior chemical separation. Similarly, oxidation of Pu(+) by NO, and nonreaction of Am(+), permit chemical resolution of the isobars of Pu and Am over 2-3 orders of magnitude relative concentration. The method provides the potential for analysis of the actinides with reduced sample matrix separation.

Mechanical behavior, damage tolerance and durability of fiber metal laminates for aircraft structures

NASA Astrophysics Data System (ADS)

Wu, Guocai

This study systematically explores the mechanical behavior, damage tolerance and durability of fiber metal laminates, a promising candidate materials system for next generation aerospace structures. The experimental results indicated that GLARE laminates exhibited a bilinear deformation behavior under static in-plane loading. Both an analytical constitutive model based on a modified classical lamination theory which incorporates the elasto-plastic behavior of aluminum alloy and a numerical simulation based on finite element modeling are used to predict the nonlinear stress-strain response and deformation behavior of GLARE laminates. The blunt notched strength of GLARE laminates increased with decreasing specimen width and decreasing hole diameter. The notched strength of GLARE laminates was evaluated based on a modified point stress criterion. A computer simulation based on finite element method was performed to study stress concentration and distribution around the notch and verify the analytical and experimental results of notched strength. Good agreement is obtained between the model predictions and experimental results. Experimental results also indicate that GLARE laminates exhibited superior impact properties to those of monolithic 2024-T3 aluminum alloy at low velocity impact loading. The GLARE 5-2/1 laminate with 0°/90°/90°/0° fiber configuration exhibits a better impact resistance than the GLARE 4-3/2 laminate with 0°/90°/0° fiber orientation. The characteristic impact energies, the damage area, and the permanent deflection of laminates are used to evaluate the impact damage resistance. The post-impact residual tensile strength under various damage states ranging from the plastic dent, barely visible impact damage (BVID), clearly visible impact damage (CVID) up to the complete perforation was also measured and compared. The post-impact fatigue behavior under various stress levels and impact damage states was extensively explored. The damage initiation and progression, failure modes and crack propagation under different loading conditions were investigated and identified with microscopy, SEM, X-ray radiography, and by chemically removing outer aluminum layers.

A receptor and neuron that activate a circuit limiting sucrose consumption.

PubMed

Joseph, Ryan M; Sun, Jennifer S; Tam, Edric; Carlson, John R

2017-03-23

The neural control of sugar consumption is critical for normal metabolism. In contrast to sugar-sensing taste neurons that promote consumption, we identify a taste neuron that limits sucrose consumption in Drosophila . Silencing of the neuron increases sucrose feeding; optogenetic activation decreases it. The feeding inhibition depends on the IR60b receptor, as shown by behavioral analysis and Ca 2+ imaging of an IR60b mutant. The IR60b phenotype shows a high degree of chemical specificity when tested with a broad panel of tastants. An automated analysis of feeding behavior in freely moving flies shows that IR60b limits the duration of individual feeding bouts. This receptor and neuron provide the molecular and cellular underpinnings of a new element in the circuit logic of feeding regulation. We propose a dynamic model in which sucrose acts via IR60b to activate a circuit that inhibits feeding and prevents overconsumption.

Deposition of TiOxNy Thin Films with Various Nitrogen Flow Rate:. Growth Behavior and Structural Properties

NASA Astrophysics Data System (ADS)

Cho, S.-J.; Jung, C.-K.; Bae, I.-S.; Song, Y.-H.; Boo, J.-H.

2011-06-01

We have deposited TiOxNy thin films on Si(100) substrates at 500 °C using RF PECVD system. Titanium iso-propoxide was used as precursor with different nitrogen flow rate to control oxygen and nitrogen contents in the films. Changes of chemical states of constituent elements in the deposited films were examined by XPS analysis. The data showed that with increasing nitrogen flow rate, the total amounts of nitrogen and titanium were increased while that of oxygen was decreased, resulting in a binding energy shift toward high energy side. The characteristics of film growth orientation and structure as well as morphology change behavior were also analyzed by XRD, TED, FT-IR, TEM, and SEM. Deposition at higher nitrogen flow rate results in finer clusters with a nanograin size and more effective photocatalytic TiOxNy thin films with hydrophilic surface.

[Natural factors influencing sleep].

PubMed

Jurkowski, Marek K; Bobek-Billewicz, Barbara

2007-01-01

Sleep is a universal phenomenon of human and animal lives, although the importance of sleep for homeo-stasis is still unknown. Sleep disturbances influence many behavioral and physiologic processes, leading to health complications including death. On the other hand, sleep improvement can beneficially influence the course of healing of many disorders and can be a prognostic of health recovery. The factors influencing sleep have different biological and chemical origins. They are classical hormones, hypothalamic releasing and inhibitory hormones, neuropeptides, peptides and others as cytokines, prostaglandins, oleamid, adenosine, nitric oxide. These factors regulate most physiologic processes and are likely elements integrating sleep with physiology and physiology with sleep in health and disorders.

Zinc isotope anomalies in Allende meteorite inclusions

NASA Technical Reports Server (NTRS)

Loss, R. D.; Lugmair, G. W.

1990-01-01

The isotopic compositions of Zn, Cr, Ti, and Ca have been measured in a number of CAIs from the Allende meteorite. The aim was to test astrophysical models which predict large excesses of Zn-66 to accompany excesses in the neutron-rich isotopes of Ca, Ti, Cr, and Ni. Some of the CAIs show clearly resolved but small excesses for Zn-66 which are at least an order of magnitude smaller than predicted. This result may simply reflect the volatility and chemical behavior of Zn as compared to the other (more refractory) anomalous elements found in these samples. Alternatively, revision of parameters and assumptions used for the model calculations may be required.

The influences of fluorine and process variations on polysilicon film stress and MOSFET hot carrier effects

NASA Technical Reports Server (NTRS)

Lowry, Lynn E.; Macwilliams, Kenneth P.; Isaac, Mary

1991-01-01

The use of fluorinated gate oxides may provide an improvement in nMOSFET reliability by enhancing hot carrier resistance. In order to clarify the mechanisms by which polysilicon processing and fluorination influence the oxide behavior, a matrix of nMOSFET structures was prepared using various processing, doping, and implantation strategies. These structures were evaluated for crystalline morphology and chemical element distribution. Mechanical stress measurements were taken on the polysilicon films from room temperature to cryogenic temperature. These examinations showed that fluorination of a structure with randomly oriented polysilicon can reduce residual mechanical stress and improve hot carrier resistance at room temperature.

Chemical element accumulation in tree bark grown in volcanic soils of Cape Verde-a first biomonitoring of Fogo Island.

PubMed

Marques, Rosa; Prudêncio, Maria Isabel; Freitas, Maria do Carmo; Dias, Maria Isabel; Rocha, Fernando

2017-05-01

Barks from Prosopis juliflora (acacia) were collected in 12 sites of different geological contexts over the volcanic Fogo Island (Cape Verde). Elemental contents of Ba, Br, Co, Cr, Fe, K, Na, Zn and some rare earth elements (REE)-La, Ce, Sm, Eu, Tb, Yb, and Lu, were obtained for biological samples and topsoils by using k 0 -standardized and comparative method of instrumental neutron activation analysis (INAA), aiming the evaluation of chemical elements uptake by acacia bark. This first biomonitoring study of Fogo Island showed that, in general, significant accumulations of trace elements present in high amounts in these soils occur. This can be partially explained by the semi-arid climate with a consequent bioavailability of chemical elements when rain drops fall in this non-polluted environment. REE enrichment factors (EFs) increase with the decrease of ionic radius. Heavy REE (HREE) are significantly enriched in bark, which agrees with their release after the primary minerals breakdown and the formation of more soluble compounds than the other REE, and uptake by plants. Among the potential harmful chemical elements, Cr appears to be partially retained in nanoparticles of iron oxides. The high EFs found in tree barks of Fogo Island are certainly of geogenic origin rather than anthropogenic input since industry and the use of fertilizers is scarce.

Visualization and modeling of sub-populations of compositional data: statistical methods illustrated by means of geochemical data from fumarolic fluids

NASA Astrophysics Data System (ADS)

Pawlowsky-Glahn, Vera; Buccianti, Antonella

In the investigation of fluid samples of a volcanic system, collected during a given period of time, one of the main goals is to discover cause-effect relationships that allow us to explain changes in the chemical composition. They might be caused by physicochemical factors, such as temperature, pressure, or non-conservative behavior of some chemical constituents (addition or subtraction of material), among others. The presence of subgroups of observations showing different behavior is evidence of unusually complex situations, which might render even more difficult the analysis and interpretation of observed phenomena. These cases require appropriate statistical techniques as well as sound a priori hypothesis concerning underlying geological processes. The purpose of this article is to present the state of the art in the methodology for a better visualization of compositional data, as well as for detecting statistically significant sub-populations. The scheme of this article is to present first the application, and then the underlying methodology, with the aim of the first motivating the second. Thus, the first part has the goal to illustrate how to understand and interpret results, whereas the second is devoted to expose how to perform a study of this kind. The case study is related to the chemical composition of a fumarole of Vulcano Island (southern Italy), called F14. The volcanic activity at Vulcano Island is subject to a continuous program of geochemical surveillance from 1978 up to now and the large data set of observations contains the main chemical composition of volcanic gases as well as trace element concentrations in the condensates of fumarolic gases. Out of the complete set of measured components, the variables H2S, HF and As, determined in samples collected from 1978 to 1993 (As is not available in recent samples) are used to characterize two groups in the original population, which proved to be statistically distinct. The choice of the variables is motivated by the importance of investigating the behavior of well-known toxicity elements, which show, like As, a significant mobility under hydrothermal conditions. The statistical methodology used for this study is based on models devised for compositional data. They include (1) the perturbation approach for a better visualization; (2) cluster analysis to detect groups; (3) confidence regions for the center of the groups to obtain graphical evidence of differences between groups; and (4) tests of hypothesis about centers and covariance structures to obtain statistical evidence about differences between groups. The fact that only three components are used allows us to illustrate the results using ternary diagrams.

A Streamline-Upwind Petrov-Galerkin Finite Element Scheme for Non-Ionized Hypersonic Flows in Thermochemical Nonequilibrium

NASA Technical Reports Server (NTRS)

Kirk, Benjamin S.; Bova, Stephen W.; Bond, Ryan B.

2011-01-01

Presentation topics include background and motivation; physical modeling including governing equations and thermochemistry; finite element formulation; results of inviscid thermal nonequilibrium chemically reacting flow and viscous thermal equilibrium chemical reacting flow; and near-term effort.

Chemical and mineralogical evaluation of slag products derived from the pyrolysis/melting treatment of MSW.

PubMed

Saffarzadeh, Amirhomayoun; Shimaoka, Takayuki; Motomura, Yoshinobu; Watanabe, Koichiro

2006-01-01

This paper provides the results of studies on the characteristics of novel material derived from pyrolysis/melting treatment of municipal solid waste in Japan. Slag products from pyrolysis/melting plants were sampled for the purpose of detailed phase analysis and characterization of heavy metal-containing phases using optical microscopy, electron probe microanalysis (EPMA), XRF and XRD. The study revealed that the slag material contains glass (over 95%), oxide and silicate minerals (spinel, melilite, pseudowollastonite), as well as individual metallic inclusions as the major constituents. A distinct chemical diversity was discovered in the interstitial glass in terms of silica content defined as low and high silica glass end members. Elevated concentrations of Zn, Cr, Cu, Pb and Ba were recorded in the bulk composition. Cu, Pb and Ba behave as incompatible elements since they have been markedly characterized as part of polymetallic alloys and insignificantly sulfides in the form of spherical metallic inclusions associated with tracer amounts of other elements such as Sb, Sn, Ni, Zn, Al, P and Si. In contrast, an appreciable amount of Zn is retained by zinc-rich end members of spinel and partially by melilite and silica glass. Chromium exhibits similar behavior, and is considerably held by Cr-rich spinel. The intense incorporation of Zn and Cr into spinel indicates the very effective enrichment of these two elements into phases more environmentally resistant than glass. There was no evidence, however, that Cu and Pb enter into the structure of the crystalline silicates or oxides that may lead to their easier leachability upon exposure to the environment.

Solid Solution Characterization in Metal by Original Tomographic Scanning Microwave Microscopy Technique

NASA Astrophysics Data System (ADS)

Bourillot, Eric; Vitry, Pauline; Optasanu, Virgil; Plassard, Cédric; Lacroute, Yvon; Montessin, Tony; Lesniewska, Eric

A general challenge in metallic components is the need for materials research to improve the service lifetime of the structural tanks or tubes subjected to harsh environments or the storage medium for the products. One major problem is the formation of lightest chemical elements bubbles or different chemical association, which can have a significant impact on the mechanical properties and structural stability of materials. The high migration mobility of these light chemical elements in solids presents a challenge for experimental characterization. Here, we present work relating to an original non-destructive, with high spatial resolution, tomographic technique based on Scanning Microwave Microscopy (SMM), which is used to visualize in-depth chemical composition of solid solution of a light chemical element in a metal. The experiments showed the capacity of SMM to detect volume. Measurements realized at different frequencies give access to a tomographic study of the sample.

Chemistry of the superheavy elements.

PubMed

Schädel, Matthias

2015-03-13

The quest for superheavy elements (SHEs) is driven by the desire to find and explore one of the extreme limits of existence of matter. These elements exist solely due to their nuclear shell stabilization. All 15 presently 'known' SHEs (11 are officially 'discovered' and named) up to element 118 are short-lived and are man-made atom-at-a-time in heavy ion induced nuclear reactions. They are identical to the transactinide elements located in the seventh period of the periodic table beginning with rutherfordium (element 104), dubnium (element 105) and seaborgium (element 106) in groups 4, 5 and 6, respectively. Their chemical properties are often surprising and unexpected from simple extrapolations. After hassium (element 108), chemistry has now reached copernicium (element 112) and flerovium (element 114). For the later ones, the focus is on questions of their metallic or possibly noble gas-like character originating from interplay of most pronounced relativistic effects and electron-shell effects. SHEs provide unique opportunities to get insights into the influence of strong relativistic effects on the atomic electrons and to probe 'relativistically' influenced chemical properties and the architecture of the periodic table at its farthest reach. In addition, they establish a test bench to challenge the validity and predictive power of modern fully relativistic quantum chemical models. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

Effects of copyrolysis of sludge with calcium carbonate and calcium hydrogen phosphate on chemical stability of carbon and release of toxic elements in the resultant biochars.

PubMed

Xu, Xuebin; Hu, Xin; Ding, Zhuhong; Chen, Yijun

2017-12-01

The potential release of toxic elements and the stability of carbon in sludge-based biochars are important on their application in soil remediation and wastewater treatment. In this study, municipal sludge was co-pyrolyzed with calcium carbonate (CaCO 3 ) and calcium dihydrogen phosphate [Ca(H 2 PO 4 ) 2 ] under 300 and 600 °C, respectively. The basic physicochemical properties of the resultant biochars were characterized and laboratory chemical oxidation and leaching experiments of toxic elements were conducted to evaluate the chemical stability of carbon in biochars and the potential release of toxic elements from biochars. Results show that the exogenous minerals changed the physico-chemical properties of the resultant biochars greatly. Biochars with exogenous minerals, especially Ca(H 2 PO 4 ) 2 , decreased the release of Zn, Cr, Ni, Cu, Pb, and As and the release ratios were less than 1%. Tessier's sequential extraction analysis revealed that labile toxic elements were transferred to residual fraction in the biochars with high pyrolysis temperature (600 °C) and exogenous minerals. Low risks for biochar-bound Pb, Zn, Cd, As, Cr, and Cu were confirmed according to risk assessment code (RAC) while the potential ecological risk index (PERI) revealed that the exogenous Ca(H 2 PO 4 ) 2 significantly decreased the risks from considerable to moderate level. Moreover, the exogenous minerals significantly increased the chemical stability of carbon in 600 °C-pyrolyzed biochars by 10-20%. These results indicated that the copyrolysis of sludge with phosphate and carbonate, especially phosphate, were effective methods to prepare the sludge-based biochars with immobilized toxic elements and enhanced chemical stability of carbon. Copyright © 2017 Elsevier Ltd. All rights reserved.

Evaluation of the behavior of clouds in a region of severe acid rain pollution in southern China: species, complexes, and variations.

PubMed

Sun, Lei; Wang, Yan; Yue, Taixing; Yang, Xueqiao; Xue, Likun; Wang, Wenxing

2015-09-01

Cloud samples were collected during the summer of 2011 and the spring of 2012 at a high-elevation site in southern China in an effort to examine the chemical characteristics of acid clouds. In total, 141 cloud samples were collected during 44 cloud events over the observation period. The dominant ionic species were SO4(2-), NH4(+), and NO3(-), contributing approximately 75% of the total inorganic ion concentration. The primary acidifying factors were sulfate and nitrate, and the primary neutralizing factors were ammonium and calcium. The volume-weighted mean (VWM) pH of the cloud water was 3.79, indicating an acidic nature. In these cloud samples, Zn and Al exhibited the highest trace metal concentrations, contributing approximately 60% of the total trace element concentration. Toxic metals, such as Pb, Ba, As, and Cr, were detected at high concentrations, indicating potential hazards for human health, vegetation, and waters in this region. Visual MINTEQ 3.0 results revealed that the majority of Zn(II) and Pb(II) existed in the form of free ions. The behavior of Al, however, differed from the behaviors of zinc and lead. The temporal variation in cloud chemistry indicated that temperature, sandstorms, and long-range transport could affect the concentrations of species. During the lifetime of a cloud event, the concentrations of the chemical species were controlled by the transfer of gases or particles to liquid droplets.

Slave finite elements: The temporal element approach to nonlinear analysis

NASA Technical Reports Server (NTRS)

Gellin, S.

1984-01-01

A formulation method for finite elements in space and time incorporating nonlinear geometric and material behavior is presented. The method uses interpolation polynomials for approximating the behavior of various quantities over the element domain, and only explicit integration over space and time. While applications are general, the plate and shell elements that are currently being programmed are appropriate to model turbine blades, vanes, and combustor liners.

Elemental Analysis of Soils by Laser Induced Breakdown Spectroscopy

NASA Astrophysics Data System (ADS)

Gondal, Mohammed Ashraf; Dastageer, Mohamed A.

The chemical and elemental composition of soil is very complex as it contains many constituents like minerals, organic matters, living organisms, fossils, air and water. Considering the diversity of soil contents, quality and usability, a systematic scientific study on the elemental and chemical composition of soil is very important. In order to study the chemical composition of soil, Laser induced breakdown spectroscopy (LIBS) has been applied recently. The important features of LIBS system and its applications for the measurement of nutrients in green house soil, on-line monitoring of remediation process of chromium polluted soil, determination of trace elements in volcanic erupted soil samples collected from ancient cenozoic lava eruption sites and detection of toxic metals in Gulf war oil spill contaminated soil using LIBS are described in this chapter.

Elemental analysis of scorpion venoms.

PubMed

Al-Asmari, AbdulRahman K; Kunnathodi, Faisal; Al Saadon, Khalid; Idris, Mohammed M

2016-01-01

Scorpion venom is a rich source of biomolecules, which can perturb physiological activity of the host on envenomation and may also have a therapeutic potential. Scorpion venoms produced by the columnar cells of venom gland are complex mixture of mucopolysaccharides, neurotoxic peptides and other components. This study was aimed at cataloguing the elemental composition of venoms obtained from medically important scorpions found in the Arabian peninsula. The global elemental composition of the crude venom obtained from Androctonus bicolor, Androctonus crassicauda and Leiurus quinquestriatus scorpions were estimated using ICP-MS analyzer. The study catalogued several chemical elements present in the scorpion venom using ICP-MS total quant analysis and quantitation of nine elements exclusively using appropriate standards. Fifteen chemical elements including sodium, potassium and calcium were found abundantly in the scorpion venom at PPM concentrations. Thirty six chemical elements of different mass ranges were detected in the venom at PPB level. Quantitative analysis of the venoms revealed copper to be the most abundant element in Androctonus sp. venom but at lower level in Leiurus quinquestriatus venom; whereas zinc and manganese was found at higher levels in Leiurus sp. venom but at lower level in Androctonus sp. venom. These data and the concentrations of other different elements present in the various venoms are likely to increase our understanding of the mechanisms of venom activity and their pharmacological potentials.

Trilateral Design and Test Code for Military Bridging and Gap-Crossing Equipment

DTIC Science & Technology

2005-05-01

Property data should be provided for individual lamina and for the ( laminat - ed) composite . The required lamina properties are identified in...Resistance Welding ....... a Brazing ......................... X Machining ..................... a Chemical Composition : Element... Machining .................. b Chemical Composition : Element % Si .................................. 0.2 max Fe

Electronic Tuning In The Hidden Order Compound URu2Si 2 Through Si → P substitution

NASA Astrophysics Data System (ADS)

Gallagher, Andrew

Crystalline materials that include 4f- and 5 f-electron elements frequently exhibit a variety of intriguing phenomena including spin and charge orderings, spin and valence fluctuations, heavy fermion behavior, breakdown of Fermi liquid behavior, and unconventional superconductivity. [5, 6, 7, 8, 9, 10, 11, 12, 13] Amongst such materials, the Kondo lattice system URu2Si2 stands out as being particularly unusual. [14, 15, 16] While at high temperature it exhibits behavior that is typical for an f-electron lattice immersed in a sea of conduction electrons, at T0 = 17:5 K there is a second order phase transition that is followed by unconventional superconductivity near Tc ≈ 1:5 K. [15] Despite three decades of work, the order parameter for the transition at T0 remains unknown and hence, it has been named "hidden order". There have been a multitude of experimental attempts to unravel hidden order, mainly through tuning of the electronic state via pressure, applied magnetic field, and chemical substitution. [17, 18] While these strategies reveal interesting phase diagrams, a longstanding challenge is that any such approach explores the phase space along an unknown vector: i.e., many different factors are affected. To address this issue, we developed a new organizational map for the U-based ThCr2Si2-type compounds that are related to URu2Si2 and thus guided, we explored a new chemical tuning axis: Si -> P. Our studies were enabled by the development of a new molten metal crystal growth method for URu2Si2 which produces high quality single crystals and allows us to introduce high vapor pressure elements, such as phosphorous. [19, 20] Si → P tuning reveals that while the high temperature Kondo lattice behavior is robust, the low temperature phenomena are remarkably sensitive to electronic tuning. [21, 22] In the URu2Si2-xPx phase diagram we find that while hidden order is monotonically suppressed and destroyed for x < 0.035, the superconducting strength evolves non-monotonically with a maximum near x = 0.01 and that superconductivity is destroyed near x ≈ 0.028. For 0.03 < x < 0.26 there is a region with Kondo coherence but no ordered state. Antiferromagnetism abruptly appears for x = 0.26. This phase diagram differs significantly from those produced by most other tuning strategies in URu2Si2, including applied pressure, and isoelectronic chemical substitution (i.e. Ru→Fe and Os), where hidden order and magnetism share a common phase boundary. [2, 23, 24] We discuss implications for understanding hidden order, its relationship to magnetism, and prospects for uncovering novel sibling electronic states.

High throughput microcantilever detector

DOEpatents

Thundat, Thomas G.; Ferrell, Thomas L.; Hansen, Karolyn M.; Tian, Fang

2004-07-20

In an improved uncoated microcantilever detector, the sample sites are placed on a separate semi-conducting substrate and the microcantilever element detects and measures the changes before and after a chemical interaction or hybridization of the sites by sensing differences of phase angle between an alternating voltage applied to the microcantilever element and vibration of the microcantilever element. In another embodiment of the invention, multiple sample sites are on a sample array wherein an array of microcantilever elements detect and measure the change before and after chemical interactions or hybridizations of the sample sites.

Seasonal growth and translocation of some major and trace elements in two Mediterranean grasses (Stipa tenacissima Loefl. ex L. and Lygeum spartum Loefl. ex L.)

NASA Astrophysics Data System (ADS)

Nedjimi, Bouzid

2018-05-01

The rangelands of Stipa tenacissima and Lygeum spartum (Poaceae) constitute one of the main typical ecosystems in the Iberian Peninsula and North Africa. This study examines the seasonal changes in aboveground biomass accumulation and translocation of some major (Ca and K) and trace elements (Br, Cr, Cu, Fe, Mn, Sr and Zn) from topsoil to shoots of these perennial grasses. Species, season and their interaction significantly affected the dry biomass (DW) and chemical composition of both species and their surrounding soil. The maximum DW was found in spring due to high physiological activity and was correlated positively with rainfall. A significant relationship between seasons and chemical elements was found. For both species the maximum concentrations of Ca, Cu and Zn were found in spring season. However L. spartum had the highest concentrations of K, Cr, Br, and Sr in autumn season, indicating exceptional ability of these species to accumulate large contents of these elements during the active growth periods. By way of contrast, in the topsoil the highest concentrations of almost all chemical elements were found in summer and autumn. Principal component analyses (PCA) showed that growth of L. spartum was highly associated with K, Ca, Zn, Br and Sr, whereas topsoil was correlated with Cu, Cr, Fe and Mn concentrations. Translocation factor (TFx) of chemical elements was not identical across the two species, demonstrating inter-specific variability to uptake chemical elements. The maximum values of TFx were recorded for K, Ca and Sr especially for L. spartum. To cope with arid conditions, S. tenacissima and L. spartum sprout quickly by increasing their rate of growth and nutrient uptake as soon as soil water is available after the rain.

The New Element Berkelium (Atomic Number 97)

DOE R&D Accomplishments Database

Seaborg, G. T.; Thompson, S. G.; Ghiorso, A.

1950-04-26

An isotope of the element with atomic number 97 has been discovered as a product of the helium-ion bombardment of americium. The name berkelium, symbol Bk, is proposed for element 97. The chemical separation of element 97 from the target material and other reaction products was made by combinations of precipitation and ion exchange adsorption methods making use of its anticipated (III) and (IV) oxidation states and its position as a member of the actinide transition series. The distinctive chemical properties made use of in its separation and the equally distinctive decay properties of the particular isotope constitute the principal evidence for the new element.

Hyperacid volcano-hydrothermal fluids from Copahue volcano, Argentina: Analogs for "subduction zone fluids"?

NASA Astrophysics Data System (ADS)

Varekamp, J. C.

2007-12-01

Hyperacid concentrated Chlorine-Sulfate brines occur in many young arc volcanoes, with pH values <1, high concentrations of volcanogenic elements (S, Cl, F, As, B) and the main rock forming elements (Ca, Al, Mg, K, Na, P). Sulfur isotope data and Silica thermometry from such fluids sampled over a ten year period from the Copahue volcanic system (Argentina) suggest reservoir temperatures of 175-300 oC, whereas the surface fluids do not exceed local boiling temperatures. These fluids are generated at much lower P-T conditions than fluids associated with a dehydrating subducted sediment complex below arc volcanoes, but their fundamental chemical compositions may have similarities. Incompatible trace element, major element concentrations and Pb isotope compositions of the fluids were used to determine the most likely rock protoliths for these fluids. Mean rock- normalized trace element diagrams then indicate which elements are quantitatively extracted from the rocks and which are left behind or precipitated in secondary phases. Most LILE show flat rock-normalized patterns, indicating close to congruent dissolution, whereas Ta-Nb-Ti show strong depletions in the rock-normalized diagrams. These HFSE are either left behind in the altered rock protolith or were precipitated along the way up. The behavior of U and Th is almost identical, suggesting that in these low pH fluids with abundant ligands Th is just as easily transported as U, which is not the case in more dilute, neutral fluids. Most analyzed fluids have steeper LREE patterns than the rocks and have negative Eu anomalies similar to the rocks. Fluids that interacted with newly intruded magma e.g., during the 2000 eruption, have much less pronounced Eu anomalies, which was most likely caused by the preferential dissolution of plagioclase when newly intruded magma interacted with the acid fluids. The fluids show a strong positive correlation between Y and Cd (similar to MORB basalts, Yi et al., JGR, 2000), suggesting that Cd is mainly a rock-derived element that may not show chalcophilic behavior. The fluids are strongly enriched (relative to rock) in As, Zn and Pb, suggesting that these elements were carried with the volcanic gas phase into the system. In summary, if these fluids are broadly similar to fluids from dehydrating subducted sediments, they tend to transport preferently the LILE, LREE, U as well as Th, while the HFSE are left behind.

Elemental Compositions of Comet 81P/Wild 2 Samples Collected by Stardust

NASA Technical Reports Server (NTRS)

Flynn, G. J.; Bleuet, P.; Borg, J.; Bradley, J.; Brenker, F.; Brennan, S.; Bridges, J.; Brownlee, D. E.; Bullock, E.; Clark, B. C.;

Chemical experiments with superheavy elements.

PubMed

Türler, Andreas

2010-01-01

Unnoticed by many chemists, the Periodic Table of the Elements has been extended significantly in the last couple of years and the 7th period has very recently been completed with eka-Rn (element 118) currently being the heaviest element whose synthesis has been reported. These 'superheavy' elements (also called transactinides with atomic number > or = 104 (Rf)) have been artificially synthesized in fusion reactions at accelerators in minute quantities of a few single atoms. In addition, all isotopes of the transactinide elements are radioactive and decay with rather short half-lives. Nevertheless, it has been possible in some cases to investigate experimentally chemical properties of transactinide elements and even synthesize simple compounds. The experimental investigation of superheavy elements is especially intriguing, since theoretical calculations predict significant deviations from periodic trends due to the influence of strong relativistic effects. In this contribution first experiments with hassium (Hs, atomic number 108), copernicium (Cn, atomic number 112) and element 114 (eka-Pb) are reviewed.

Monte Carlo simulation of expert judgments on human errors in chemical analysis--a case study of ICP-MS.

PubMed

Kuselman, Ilya; Pennecchi, Francesca; Epstein, Malka; Fajgelj, Ales; Ellison, Stephen L R

2014-12-01

Monte Carlo simulation of expert judgments on human errors in a chemical analysis was used for determination of distributions of the error quantification scores (scores of likelihood and severity, and scores of effectiveness of a laboratory quality system in prevention of the errors). The simulation was based on modeling of an expert behavior: confident, reasonably doubting and irresolute expert judgments were taken into account by means of different probability mass functions (pmfs). As a case study, 36 scenarios of human errors which may occur in elemental analysis of geological samples by ICP-MS were examined. Characteristics of the score distributions for three pmfs of an expert behavior were compared. Variability of the scores, as standard deviation of the simulated score values from the distribution mean, was used for assessment of the score robustness. A range of the score values, calculated directly from elicited data and simulated by a Monte Carlo method for different pmfs, was also discussed from the robustness point of view. It was shown that robustness of the scores, obtained in the case study, can be assessed as satisfactory for the quality risk management and improvement of a laboratory quality system against human errors. Copyright © 2014 Elsevier B.V. All rights reserved.

Journal of Chemical Education: Software.

ERIC Educational Resources Information Center

Journal of Chemical Education, 1989

1989-01-01

Discusses a visual database of information about chemical elements. Uses a single sided 12-inch, 30-minute, CAV-type videodisk. Contains a picture of almost every element in its stable form at room temperature and normal atmospheric pressure. Can be used with the video controller from "KC? Discoverer." (MVL)

Bio-metals imaging and speciation in cells using proton and synchrotron radiation X-ray microspectroscopy

PubMed Central

Ortega, Richard; Devès, Guillaume; Carmona, Asunción

2009-01-01

The direct detection of biologically relevant metals in single cells and of their speciation is a challenging task that requires sophisticated analytical developments. The aim of this article is to present the recent achievements in the field of cellular chemical element imaging, and direct speciation analysis, using proton and synchrotron radiation X-ray micro- and nano-analysis. The recent improvements in focusing optics for MeV-accelerated particles and keV X-rays allow application to chemical element analysis in subcellular compartments. The imaging and quantification of trace elements in single cells can be obtained using particle-induced X-ray emission (PIXE). The combination of PIXE with backscattering spectrometry and scanning transmission ion microscopy provides a high accuracy in elemental quantification of cellular organelles. On the other hand, synchrotron radiation X-ray fluorescence provides chemical element imaging with less than 100 nm spatial resolution. Moreover, synchrotron radiation offers the unique capability of spatially resolved chemical speciation using micro-X-ray absorption spectroscopy. The potential of these methods in biomedical investigations will be illustrated with examples of application in the fields of cellular toxicology, and pharmacology, bio-metals and metal-based nano-particles. PMID:19605403

Influence of chemical disorder on energy dissipation and defect evolution in advanced alloys

DOE PAGES

Zhang, Yanwen; Jin, Ke; Xue, Haizhou; ...

2016-08-01

We report that historically, alloy development with better radiation performance has been focused on traditional alloys with one or two principal element(s) and minor alloying elements, where enhanced radiation resistance depends on microstructural or nanoscale features to mitigate displacement damage. In sharp contrast to traditional alloys, recent advances of single-phase concentrated solid solution alloys (SP-CSAs) have opened up new frontiers in materials research. In these alloys, a random arrangement of multiple elemental species on a crystalline lattice results in disordered local chemical environments and unique site-to-site lattice distortions. Based on closely integrated computational and experimental studies using a novel setmore » of SP-CSAs in a face-centered cubic structure, we have explicitly demonstrated that increasing chemical disorder can lead to a substantial reduction in electron mean free paths, as well as electrical and thermal conductivity, which results in slower heat dissipation in SP-CSAs. The chemical disorder also has a significant impact on defect evolution under ion irradiation. Considerable improvement in radiation resistance is observed with increasing chemical disorder at electronic and atomic levels. Finally, the insights into defect dynamics may provide a basis for understanding elemental effects on evolution of radiation damage in irradiated materials and may inspire new design principles of radiation-tolerant structural alloys for advanced energy systems.« less

Origin and Evolution of the Elements

NASA Astrophysics Data System (ADS)

McWilliam, Andrew; Rauch, Michael

2004-09-01

Introduction; List of participants; 1. Mount Wilson Observatory contributions to the study of cosmic abundances of the chemical elements George W. Preston; 2. Synthesis of the elements in stars: B2FH and beyond E. Margaret Burbidge; 3. Stellar nucleosynthesis: a status report 2003 David Arnett; 4. Advances in r-process nucleosynthesis John J. Cowan and Christopher Sneden; 5. Element yields of intermediate-mass stars Richard B. C. Henry; 6. The impact of rotation on chemical abundances in red giant branch stars Corinne Charbonnel; 7. s-processing in AGB stars and the composition of carbon stars Maurizio Busso, Oscar Straniero, Roberto Gallino, and Carlos Abia; 8. Models of chemical evolution Francesca Matteucci; 9. Model atmospheres and stellar abundance analysis Bengt Gustafsson; 10. The light elements: lithium, beryllium, and boron Ann Merchant Boesgaard; 11. Extremely metal-poor stars John E. Norris; 12. Thin and thick galactic disks Poul E. Nissen; 13. Globular clusters and halo field stars Christopher Sneden, Inese I. Ivans and Jon P. Fulbright; 14. Chemical evolution in ω Centauri Verne V. Smith; 15. Chemical composition of the Magellanic Clouds, from young to old stars Vanessa Hill; 16. Detailed composition of stars in dwarf spheroidal galaxies Matthew D. Shetrone; 17. The evolutionary history of Local Group irregular galaxies Eva K. Grebel; 18. Chemical evolution of the old stellar populations of M31 R. Michael Rich; 19. Stellar winds of hot massive stars nearby and beyond the Local Group Fabio Bresolin and Rolf P. Kudritzki; 20. Presolar stardust grains Donald D. Clayton and Larry R. Nittler; 21. Interstellar dust B. T. Draine; 22. Interstellar atomic abundances Edward B. Jenkins; 23. Molecules in the interstellar medium Tommy Wiklind; 24. Metal ejection by galactic winds Crystal L. Martin; 25. Abundances from the integrated light of globular clusters and galaxies Scott C. Trager; 26. Abundances in spiral and irregular galaxies Donald R. Garnett; 27. Chemical composition of the intracluster medium Michael Loewenstein; 28. Quasar elemental abundances and host galaxy evolution Fred Hamann, Matthias Dietrich, Bassem M. Sabra, and Craig Warner; 29. Chemical abundances in the damped Lyα systems Jason X. Prochaska; 30. Intergalactic medium abundances Robert F. Carswell; 31. Conference summary Bernard E. J. Pagel.

Rhenium in seawater - Confirmation of generally conservative behavior

NASA Technical Reports Server (NTRS)

Anbar, A. D.; Creaser, R. A.; Papanastassiou, D. A.; Wasserburg, G. J.

1992-01-01

A depth profile of the concentration of Re was measured in the Pacific Ocean using a technique developed for the clean chemical separation and the precise measurement of Re by isotope dilution and negative thermal ionization mass spectrometry (ID-NTIMS). We obtain a narrow range for Re from 7.20 +/- 0.03 to 7.38 +/- 0.03 ng/kg for depths between 45 m and 4700 m. This demonstrates that Re is relatively well mixed throughout the water column and confirms the theoretical prediction that the behavior of Re in the oceans is conservative. When examined in detail, both salinity and the concentration of Re increase by approximately 1.5 percent between 400 and 4700 m, a correlation consistent with conservative behavior. However, Re appears to be depleted relative to salinity by 1.0-1.5 percent at 100 m, and enriched by approximately 4 percent at the surface. These observations suggest a minor level of Re scavenging in near surface waters, and an input of Re to the ocean surface. This work demonstrates the utility of geochemical investigations of certain trace elements not previously been amenable to detailed study.

Contrasting impact of organic and inorganic nanoparticles and colloids on the behavior of particle-reactive elements in tropical estuaries: An experimental study

NASA Astrophysics Data System (ADS)

Merschel, Gila; Bau, Michael; Dantas, Elton Luiz

2017-01-01

Estuarine processes may affect the flux of dissolved organic carbon (DOC), iron and other particle-reactive elements such as the rare earth elements and yttrium (REY), into the ocean via salt-induced coagulation and subsequent removal of river-borne (nano-)particles and colloids. We experimentally assessed the impact of the admixture of seawater on DOC, Fe and REY associated with inorganic and organic nanoparticles and colloids (NPCs) present in tropical rivers, using Rio Solimões and Rio Negro, which are particularly rich in inorganic and organic NPCs, respectively, as river water endmembers. Similar to the conservative elements Sr, Rb and U, DOC behaves conservatively in all mixing experiments, whereas strong removal of Fe and REY (and preferential removal of light over heavy REY and of Ce relative to La and Pr) is confined to experiments with inorganic NPC-rich Rio Solimões water. This removal already occurs at very low salinity and is due to the aggregation of the inorganic NPCs. However, REY removal efficiency increases gradually with increasing salinity, which is in marked contrast to DOC-poor Arctic river waters from which REY removal at lowest salinity is significantly stronger. This suggests that the DOC concentrations in the water have a profound impact on the estuarine mixing behavior of particle-reactive elements. In marked contrast to the Rio Solimões mixing experiment, Fe and the REY in experiments with Rio Negro water behave similarly to DOC and mix conservatively with seawater, indicating that the organic NPCs, most of which are humic and fulvic acids, and their associated trace elements are much less susceptible to coagulation and estuarine removal than inorganic ones. Even at higher salinities, estuarine REY removal from inorganic NPC-rich Rio Solimões water significantly exceeds REY removal from organic NPC-rich Rio Negro water. Hence, the combination of higher element concentrations in and of less estuarine removal from organic NPC-rich rivers compared to inorganic NPC-rich rivers indicates that the former are a more important source of particle-reactive elements to the oceans than previously thought. This suggests that chemical complexation with organic ligands, such as humic and fulvic acids, may have a strong impact on the riverine flux and on the marine inventory of particle-reactive elements, and hence may play an important role for the isotopic composition of such elements in seawater.

Chemical elements in Mediterranean macroalgae. A review.

PubMed

Bonanno, Giuseppe; Orlando-Bonaca, Martina

2018-02-01

This review analyzes the state of knowledge on the capacity of Mediterranean macroalgae to accumulate, tolerate and biomonitor macro- and micro-elements present in seawater and sediments. The results show that the investigated macroalgal species amount to c. 5.0% of all Mediterranean native Rhodophyta, Chlorophyta and Ochrophyta. The most commonly analyzed elements in algae were Pb, Cd, Zn and Cu, whereas very few studies were available for macroelements such as Ca and K. Uptake mechanisms and the factors influencing accumulation are overall well known, but the available studies are restricted to a limited number of chemical elements and algal species. This review also shows that macroalgae can accumulate and tolerate high concentrations of chemical elements, and can act as effective bioindicators of marine pollution. Phytotoxic limits for algal species are not clearly identified by the available studies and require further investigation. Future research should focus on the development of protocols for long-term biomonitoring programmes through the use of macroalgae. Future studies also need to investigate the biomagnification of toxic trace elements in macroalgae-based food webs. Copyright © 2017 Elsevier Inc. All rights reserved.

Dwarf Galaxies: Laboratories for Nucleosynthesis and Chemical Evolution

NASA Astrophysics Data System (ADS)

Kirby, Evan N.

2018-06-01

The dwarf galaxies in the Local Group are excellent laboratories for studying the creation of the elements (nucleosynthesis) and the build-up of those elements over time (chemical evolution). The galaxies' proximity permits spectroscopy of individual stars, from which detailed elemental abundances can be measured. Their small sizes and, in some cases, short star formation lifetimes imprinted chemical histories that are easy to interpret relative to larger, more complex galaxies, like the Milky Way.I will briefly review some techniques for measuring elemental abundances from medium-resolution spectroscopy of individual stars. I will show how the metallicity distributions of dwarf galaxies reflect their gas content at the time they were forming stars. Then, I will show how the ratio of alpha elements (for example, magnesium) to iron reveals the star formation history. Finally, I will use certain elements to tease out details of nucleosynthetic events. For example, low manganese and cobalt abundances indicate that the typical Type Ia supernova in dwarf galaxies was a low-density white dwarf, and the evolution of barium suggests that neutron star mergers were most likely responsible for the majority of neutron-capture elements in smaller dwarf galaxies.

The GALAH survey: scientific motivation

NASA Astrophysics Data System (ADS)

De Silva, G. M.; Freeman, K. C.; Bland-Hawthorn, J.; Martell, S.; de Boer, E. Wylie; Asplund, M.; Keller, S.; Sharma, S.; Zucker, D. B.; Zwitter, T.; Anguiano, B.; Bacigalupo, C.; Bayliss, D.; Beavis, M. A.; Bergemann, M.; Campbell, S.; Cannon, R.; Carollo, D.; Casagrande, L.; Casey, A. R.; Da Costa, G.; D'Orazi, V.; Dotter, A.; Duong, L.; Heger, A.; Ireland, M. J.; Kafle, P. R.; Kos, J.; Lattanzio, J.; Lewis, G. F.; Lin, J.; Lind, K.; Munari, U.; Nataf, D. M.; O'Toole, S.; Parker, Q.; Reid, W.; Schlesinger, K. J.; Sheinis, A.; Simpson, J. D.; Stello, D.; Ting, Y.-S.; Traven, G.; Watson, F.; Wittenmyer, R.; Yong, D.; Žerjal, M.

2015-05-01

The Galactic Archaeology with HERMES (GALAH) survey is a large high-resolution spectroscopic survey using the newly commissioned High Efficiency and Resolution Multi-Element Spectrograph (HERMES) on the Anglo-Australian Telescope. The HERMES spectrograph provides high-resolution (R ˜ 28 000) spectra in four passbands for 392 stars simultaneously over a 2 deg field of view. The goal of the survey is to unravel the formation and evolutionary history of the Milky Way, using fossil remnants of ancient star formation events which have been disrupted and are now dispersed throughout the Galaxy. Chemical tagging seeks to identify such dispersed remnants solely from their common and unique chemical signatures; these groups are unidentifiable from their spatial, photometric or kinematic properties. To carry out chemical tagging, the GALAH survey will acquire spectra for a million stars down to V ˜ 14. The HERMES spectra of FGK stars contain absorption lines from 29 elements including light proton-capture elements, α-elements, odd-Z elements, iron-peak elements and n-capture elements from the light and heavy s-process and the r-process. This paper describes the motivation and planned execution of the GALAH survey, and presents some results on the first-light performance of HERMES.

Plants' essential chemical elements

Treesearch

Kevin T. Smith

2007-01-01

Every garden center and hardware store sells fertilizer guaranteed to "feed" plants. In a strict sense, we can't feed plants. Food contains an energy source. Green plants capture solar energy and make their own food through photosynthesis! Photosynthesis and other metabolic processes require chemical elements in appropriate doses for plants to survive...

Human Geophagia, Calabash Chalk and Undongo: Mineral Element Nutritional Implications

PubMed Central

Abrahams, Peter W.; Davies, Theo C.; Solomon, Abiye O.; Trow, Amanda J.; Wragg, Joanna

2013-01-01

The prime aim of our work is to report and comment on the bioaccessible concentrations – i.e., the soluble content of chemical elements in the gastrointestinal environment that is available for absorption – of a number of essential mineral nutrients and potentially harmful elements (PHEs) associated with the deliberate ingestion of African geophagical materials, namely Calabash chalk and Undongo. The pseudo-total concentrations of 13 mineral nutrients/PHEs were quantified following a nitric-perchloric acid digestion of nine different Calabash chalk samples, and bioaccessible contents of eight of these chemical elements were determined in simulated saliva/gastric and intestinal solutions obtained via use of the Fed ORganic Estimation human Simulation Test (FOREhST) in vitro procedure. The Calabash chalk pseudo-total content of the chemical elements is often below what may be regarded as average for soils/shales, and no concentration is excessively high. The in vitro leachate solutions had concentrations that were often lower than those of the blanks used in our experimental procedure, indicative of effective adsorption: lead, a PHE about which concern has been previously raised in connection with the consumption of Calabash chalk, was one such chemical element where this was evident. However, some concentrations in the leachate solutions are suggestive that Calabash chalk can be a source of chemical elements to humans in bioaccessible form, although generally the materials appear to be only a modest supplier: this applies even to iron, a mineral nutrient that has often been linked to the benefits of geophagia in previous academic literature. Our investigations indicate that at the reported rates of ingestion, Calabash chalk on the whole is not an important source of mineral nutrients or PHEs to humans. Similarly, although Undongo contains elevated pseudo-total concentrations of chromium and nickel, this soil is not a significant source to humans for any of the bioaccessible elements investigated. PMID:23308189

Human geophagia, calabash chalk and undongo: mineral element nutritional implications.

PubMed

Abrahams, Peter W; Davies, Theo C; Solomon, Abiye O; Trow, Amanda J; Wragg, Joanna

2013-01-01

The prime aim of our work is to report and comment on the bioaccessible concentrations - i.e., the soluble content of chemical elements in the gastrointestinal environment that is available for absorption - of a number of essential mineral nutrients and potentially harmful elements (PHEs) associated with the deliberate ingestion of African geophagical materials, namely Calabash chalk and Undongo. The pseudo-total concentrations of 13 mineral nutrients/PHEs were quantified following a nitric-perchloric acid digestion of nine different Calabash chalk samples, and bioaccessible contents of eight of these chemical elements were determined in simulated saliva/gastric and intestinal solutions obtained via use of the Fed ORganic Estimation human Simulation Test (FOREhST) in vitro procedure. The Calabash chalk pseudo-total content of the chemical elements is often below what may be regarded as average for soils/shales, and no concentration is excessively high. The in vitro leachate solutions had concentrations that were often lower than those of the blanks used in our experimental procedure, indicative of effective adsorption: lead, a PHE about which concern has been previously raised in connection with the consumption of Calabash chalk, was one such chemical element where this was evident. However, some concentrations in the leachate solutions are suggestive that Calabash chalk can be a source of chemical elements to humans in bioaccessible form, although generally the materials appear to be only a modest supplier: this applies even to iron, a mineral nutrient that has often been linked to the benefits of geophagia in previous academic literature. Our investigations indicate that at the reported rates of ingestion, Calabash chalk on the whole is not an important source of mineral nutrients or PHEs to humans. Similarly, although Undongo contains elevated pseudo-total concentrations of chromium and nickel, this soil is not a significant source to humans for any of the bioaccessible elements investigated.

Interplay between Diffusion, Accretion and Nuclear Reactions in the Atmospheres of Sirius and Przybylski's Star

NASA Astrophysics Data System (ADS)

Yushchenko, A.; Gopka, V.; Goriely, S.; Lambert, D.; Shavrina, A.; Kang, Y. W.; Rostopchin, S.; Valyavin, G.; Lee, B.-C.; Kim, C.

2007-06-01

The abundance anomalies in chemically peculiar B-F stars are usually explained by diffusion of chemical elements in the stable atmospheres of these stars. But it is well known that peculiar stars with similar temperatures and gravities show very different chemical compositions. We show that the abundance patterns of several stars can be influenced by accretion and (or) nuclear reactions in stellar atmospheres. The first case is one of the hottest Am stars - Sirius. We determined the abundances of more than 50 chemical elements in the atmosphere of Sirius A and show that Sirius A was contaminated by s-process enriched matter from Sirius B (now a white dwarf). The second case is the well known Przybylski's star. The abundance pattern of this star is the second most studied one after the Sun with abundances determined for about 60 chemical elements. Spectral lines of radioactive elements with short decay times were found in the spectrum of this star. We report the results of our investigation on the stratification of chemical elements in the atmosphere of Przybylski's star and the new identification of lines corresponding to short-lived actinides in its spectrum. Possible explanations of the abundances pattern of Przybylski's star (as well as HR465 and HD965) can be the natural radioactive decays of thorium and uranium, the explosion of a companion as a supernova or the spallation reactions. These three hypotheses and (or) diffusion can possibly explain the abundance pattern of Przybylski's star and several similar objects such as HR465 and HD965.

Modeling of the viscoelastic behavior of a polyimide matrix at elevated temperature

NASA Astrophysics Data System (ADS)

Crochon, Thibaut

Use of Polymer Matrix Composite Materials (PMCMs) in aircraft engines requires materials able to withstand extreme service conditions, such as elevated temperatures, high mechanical loadings and an oxidative environment. In such an environment, the polymer matrix is likely to exhibit a viscoelastic behavior dependent on the mechanical loading and temperature. In addition, the combined effects of elevated temperature and the environment near the engines are likely to increase physical as well as chemical aging. These various parameters need to be taken into consideration for the designer to be able to predict the material behavior over the service life of the components. The main objective of this thesis was to study the viscoelastic behavior of a high temperature polyimide matrix and develop a constitutive theory able to predict the material behavior for every of service condition. Then, the model had to have to be implemented into commercially available finite-element software such as ABAQUS or ANSYS. Firstly, chemical aging of the material at service temperature was studied. To that end, a thermogravimetric analysis of the matrix was conducted on powder samples in air atmosphere. Two kinds of tests were performed: i) kinetic tests in which powder samples were heated at a constant rate until complete sublimation; ii) isothermal tests in which the samples were maintained at a constant temperature for 24 hours. The first tests were used to develop a degradation model, leading to an excellent fit of the experimental data. Then, the model was used to predict the isothermal data but which much less success, particularly for the lowest temperatures. At those temperatures, the chemical degradation was preceded by an oxidation phase which the model was not designed to predict. Other isothermal degradation tests were also performed on tensile tests samples instead of powders. Those tests were conducted at service temperature for a much longer period of time. The samples masses, volume and tensile properties were recorded after 1, 4, 9 and 17 months. The results of those tests showed that after 17 months, the matrix lost about 5% of its mass and volume and as much as 19%, 30% and 10% of its Young's modulus, stress and strain at break, respectively. The second step consisted in studying the viscoelastic behavior of the matrix under various conditions and develop a constitutive theory to model its mechanical behavior. That theory was developed using the framework laid out by Schapery in 1964, using the Thermodynamics of Irreversible Processes. The main advantage of Schapery-type constitutive theories is that the effects of various parameters such as stresses, temperature and physical ageing can be taken into account by using user-defined explicit nonlinearizing functions. Tensile samples of the material were tested at service temperature using strain gages rosettes in order to study the matrix 3D behavior. It was found that the Poisson's ratio was time-independent, meaning that its retardation times spectrum was the same as the compliance function. Furthermore, at this temperature, it was found that the viscoelastic behavior was independent of the stress level. Those two observations led to the conclusion that the material was linearly viscoelastic and could be represented with a 1D constitutive theory. From this conclusion, and also due to the scarcity of material available, it was decided to use 3-point bending tests for studying the impact of temperature and physical ageing. Following Struik's methodology, the material was heated at ageing temperature and then series of creep tests at increasing intervals were performed. It was found that the material became stiffer as the ageing time increased, but it also became softer for increasing temperatures. A model was developed in which Schapery's nonlinearizing functions were obtained from experimental data. The model was validated with complex thermo-mechanical histories comprising several creep tests as well as temperature up- and down-jumps. The experimental data were predicted with excellent accuracy. Finally, the last step consisted in implementing the constitutive theory into a finite-element software. To that end, a new procedure was developed. Instead of the classical methods which deal with Schapery's hereditary integral, the method went back to the evolution equations which are the basis of the integral. The evolution equations were solved with well-known finite-difference schemes such as Backward-Euler, Crank-Nicholson or Runge-Kutta. The numerical model thus obtained could then easily be implemented into finite-element software. In this thesis, a thorough examination of the mechanical properties of a polyimide matrix was conducted. It was found that for such materials, the service temperature is so elevated that chemical ageing has a defining importance on components life. Furthermore, it was found that viscoelastic behavior was only dependent on temperature and physical ageing, but not on the stress levels. (Abstract shortened by ProQuest.).

Modeling and simulation of axisymmetric stagnation flames

NASA Astrophysics Data System (ADS)

Sone, Kazuo

Laminar flame modeling is an important element in turbulent combustion research. The accuracy of a turbulent combustion model is highly dependent upon our understanding of laminar flames and their behavior in many situations. How much we understand combustion can only be measured by how well the model describes and predicts combustion phenomena. One of the most commonly used methane combustion models is GRI-Mech 3.0. However, how well the model describes the reacting flow phenomena is still uncertain even after many attempts to validate the model or quantify uncertainties. In the present study, the behavior of laminar flames under different aerodynamic and thermodynamic conditions is studied numerically in a stagnation-flow configuration. In order to make such a numerical study possible, the spectral element method is reformulated to accommodate the large density variations in methane reacting flows. In addition, a new axisymmetric basis function set for the spectral element method that satisfies the correct behavior near the axis is developed, and efficient integration techniques are developed to accurately model axisymmetric reacting flow within a reasonable amount of computational time. The numerical method is implemented using an object-oriented programming technique, and the resulting computer program is verified with several different verification methods. The present study then shows variances with the commonly used GRI-Mech 3.0 chemical kinetics model through a direct simulation of laboratory flames that allows direct comparison to experimental data. It is shown that the methane combustion model based on GRI-Mech 3.0 works well for methane-air mixtures near stoichiometry. However, GRI-Mech 3.0 leads to an overprediction of laminar flame speed for lean mixtures and an underprediction for rich mixtures. This result is slightly different from conclusion drawn in previous work, in which experimental data are compared with a one-dimensional numerical solutions. Detailed analysis reveals that flame speed is sensitive to even slight flame front curvature as well as its finite extension in the radial direction. Neither of these can be incorporated in one-dimensional flow modeli

Dynamic control and information processing in chemical reaction systems by tuning self-organization behavior

NASA Astrophysics Data System (ADS)

Lebiedz, Dirk; Brandt-Pollmann, Ulrich

2004-09-01

Specific external control of chemical reaction systems and both dynamic control and signal processing as central functions in biochemical reaction systems are important issues of modern nonlinear science. For example nonlinear input-output behavior and its regulation are crucial for the maintainance of the life process that requires extensive communication between cells and their environment. An important question is how the dynamical behavior of biochemical systems is controlled and how they process information transmitted by incoming signals. But also from a general point of view external forcing of complex chemical reaction processes is important in many application areas ranging from chemical engineering to biomedicine. In order to study such control issues numerically, here, we choose a well characterized chemical system, the CO oxidation on Pt(110), which is interesting per se as an externally forced chemical oscillator model. We show numerically that tuning of temporal self-organization by input signals in this simple nonlinear chemical reaction exhibiting oscillatory behavior can in principle be exploited for both specific external control of dynamical system behavior and processing of complex information.

The Chemical Composition of the Active Stars

NASA Astrophysics Data System (ADS)

Glazunova, L. V.

The comparison of the results of the studies of the active stars' chemical composition obtained by different authors has been performed. It was concluded that the difference between the abundances of some elements in active and inactive stars becomes significant (> 3σ) only for the active stars with high chromospheric activity (lgR'HK > -4). This is the case primarily for the light elements, namely Li, Na and Al, as well as heavy elements with Z > 30.

Influence of trace elements on dental enamel properties: A review.

PubMed

Qamar, Zeeshan; Haji Abdul Rahim, Zubaidah Binti; Chew, Hooi Pin; Fatima, Tayyaba

2017-01-01

Dental enamel, an avascular, irreparable, outermost and protective layer of the human clinical crown has a potential to withstand the physico-chemical effects and forces. These properties are being regulated by a unique association among elements occurring in the crystallites setup of human dental enamel. Calcium and phosphate are the major components (hydroxyapatite) in addition to some trace elements which have a profound effect on enamel. The current review was planned to determine the aptitude of various trace elements to substitute and their influence on human dental enamel in terms of physical and chemical properties.

Use of chemical mechanical polishing in micromachining

DOEpatents

Nasby, Robert D.; Hetherington, Dale L.; Sniegowski, Jeffry J.; McWhorter, Paul J.; Apblett, Christopher A.

1998-01-01

A process for removing topography effects during fabrication of micromachines. A sacrificial oxide layer is deposited over a level containing functional elements with etched valleys between the elements such that the sacrificial layer has sufficient thickness to fill the valleys and extend in thickness upwards to the extent that the lowest point on the upper surface of the oxide layer is at least as high as the top surface of the functional elements in the covered level. The sacrificial oxide layer is then polished down and planarized by chemical-mechanical polishing. Another layer of functional elements is then formed upon this new planarized surface.

Lead isotope relations in oceanic Ridge basalts from the Juan de Fuca-Gorda Ridge area N.E. Pacific Ocean

USGS Publications Warehouse

Church, S.E.; Tatsumoto, M.

1975-01-01

Lead isotopic analyses of a suite of basaltic rocks from the Juan de Fuca-Gorda Ridge and nearby seamounts confirm an isotopically heterogeneous mantle known since 1966. The process of mixing during partial melting of a heterogeneous mantle necessarily produces linear data arrays that can be interpreted as secondary isochrons. Moreover, the position of the entire lead isotope array, with respect to the geochron, requires that U/Pb and Th/Pb values are progressively increased over the age of the earth. Partial melting theory also dictates analogous behavior for the other incompatible trace elements. This process explains not only the LIL element character of MOR basalts, but also duplicates the spread of radiogenic lead data collected from alkali-rich oceanic basalts. This dynamic, open-system model of lead isotopic and chemical evolution of the mantle is believed to be the direct result of tectonic flow and convective overturn within the mantle and is compatible with geophysical models of a dynamic earth. ?? 1975 Springer-Verlag.

Computational Fluid Dynamics–Discrete Element Method (CFD-DEM) Study of Mass-Transfer Mechanisms in Riser Flow

PubMed Central

2017-01-01

We report a computational fluid dynamics–discrete element method (CFD-DEM) simulation study on the interplay between mass transfer and a heterogeneous catalyzed chemical reaction in cocurrent gas-particle flows as encountered in risers. Slip velocity, axial gas dispersion, gas bypassing, and particle mixing phenomena have been evaluated under riser flow conditions to study the complex system behavior in detail. The most important factors are found to be directly related to particle cluster formation. Low air-to-solids flux ratios lead to more heterogeneous systems, where the cluster formation is more pronounced and mass transfer more influenced. Falling clusters can be partially circumvented by the gas phase, which therefore does not fully interact with the cluster particles, leading to poor gas–solid contact efficiencies. Cluster gas–solid contact efficiencies are quantified at several gas superficial velocities, reaction rates, and dilution factors in order to gain more insight regarding the influence of clustering phenomena on the performance of riser reactors. PMID:28553011

Computational Fluid Dynamics-Discrete Element Method (CFD-DEM) Study of Mass-Transfer Mechanisms in Riser Flow.

PubMed

Carlos Varas, Álvaro E; Peters, E A J F; Kuipers, J A M

2017-05-17

We report a computational fluid dynamics-discrete element method (CFD-DEM) simulation study on the interplay between mass transfer and a heterogeneous catalyzed chemical reaction in cocurrent gas-particle flows as encountered in risers. Slip velocity, axial gas dispersion, gas bypassing, and particle mixing phenomena have been evaluated under riser flow conditions to study the complex system behavior in detail. The most important factors are found to be directly related to particle cluster formation. Low air-to-solids flux ratios lead to more heterogeneous systems, where the cluster formation is more pronounced and mass transfer more influenced. Falling clusters can be partially circumvented by the gas phase, which therefore does not fully interact with the cluster particles, leading to poor gas-solid contact efficiencies. Cluster gas-solid contact efficiencies are quantified at several gas superficial velocities, reaction rates, and dilution factors in order to gain more insight regarding the influence of clustering phenomena on the performance of riser reactors.

Chemical element concentrations in four lichens on a transect entering Voyageurs National Park

USGS Publications Warehouse

Bennett, J.; Wetmore, C.M.

1997-01-01

A three factor transect study was conducted to test the hypothesis that chemical elements from air emissions in the vicinity of International Falls, Minnesota could not be detected in lichens along a 24 km transect reaching into Voyageurs National Park. It was hypothesized that element concentrations in lichens would decline exponentially downwind and would reach background values at a distance before the park boundary. Four species (Cladina rangiferina, Evernia mesomorpha, Hypogymnia physodes, and Parmelia sulcata) were sampled at ten sites for 3 years and 17 chemical elements were measured. The most notable result was a curvilinear geographic trend for many elements, which decreased from International Falls and then increased towards the park. This trend was significant for many anthropogenic elements, including S, Hg, Cd, and Cr, and for all four species. This type of distribution pattern has been observed in Hypogymnia physodes in other studies downwind of a steel mill and an oil refinery. Cladina, a ground-dwelling lichen, generally had lower tissue concentrations of the elements than the three epiphytic species. Tissue concentrations over the 3 years of sampling declined an average of 12%. Sufficient evidence exists to conclude that lichen tissue element concentrations in the vicinity of International Falls may be related to local air emissions, and that an exponential decline of element concentrations downwind of the sources does not apply to this situation.

Predicting Water Quality Problems Associated with Coal Fly Ash Disposal Facilities Using a Trace Element Partitioning Study

NASA Astrophysics Data System (ADS)

Bhattacharyya, S.; Donahoe, R. J.; Graham, E. Y.

2006-12-01

For much of the U.S., coal-fired power plants are the most important source of electricity for domestic and industrial use. Large quantities of fly ash and other coal combustion by-products are produced every year, the majority of which is impounded in lagoons and landfills located throughout the country. Many older fly ash disposal facilities are unlined and have been closed for decades. Fly ash often contains high concentrations of toxic trace elements such as arsenic, boron, chromium, molybdenum, nickel, selenium, lead, strontium and vanadium. Trace elements present in coal fly ash are of potential concern due to their toxicity, high mobility in the environment and low drinking water MCL values. Concern about the potential release of these toxic elements into the environment due to leaching of fly ash by acid rain, groundwater or acid mine drainage has prompted the EPA to develop national standards under the subtitle D of the Resource Conservation and Recovery Act (RCRA) to regulate ash disposal in landfills and surface impoundments. An attempt is made to predict the leaching of toxic elements into the environment by studying trace element partitioning in coal fly ash. A seven step sequential chemical extraction procedure (SCEP) modified from Filgueiras et al. (2002) is used to determine the trace element partitioning in seven coal fly ash samples collected directly from electric power plants. Five fly ash samples were derived from Eastern Bituminous coal, one derived from Western Sub-bituminous coal and the other derived from Northern Lignite. The sequential chemical extraction procedure gives valuable information on the association of trace elements: 1) soluble fraction, 2) exchangeable fraction, 3) acid soluble fraction, 4) easily reducible fraction, 5) moderately reducible fraction, 6) poorly reducible fraction and 7) oxidizable organics/sulfide fraction. The trace element partitioning varies with the composition of coal fly ash which is influenced by the type of coal burned. Preliminary studies show that in some fly ash samples, significant amounts of As, B, Mo, Se, Sr and V are associated with the soluble and exchangeable fraction, and thus would be highly mobile in the environment. Lead, on the other hand, is mainly associated with the amorphous Fe and Mn oxide fractions and would be highly immobile in oxidizing conditions, but mobile in reducing conditions. Ni and Cr show different associations in different fly ash samples. In most fly ash samples, significant amounts of the trace elements are associated with more stable fractions that do not threaten the environment. The study of trace element partitioning in coal fly ash thus helps us to predict their leaching behavior under various conditions.

Chemical composition of rocks and soils at Taurus-Littrow

NASA Technical Reports Server (NTRS)

Rose, H. J., Jr.; Cuttitta, F.; Berman, S.; Brown, F. W.; Carron, M. K.; Christian, R. P.; Dwornik, E. J.; Greenland, L. P.

1974-01-01

Seventeen soils and seven rock samples were analyzed for major elements, minor elements, and trace elements. Unlike the soils at previous Apollo sites, which showed little difference in composition at each collection area, the soils at Taurus-Littrow vary widely. Three soil types are evident, representative of (1) the light mantle at the South Massif, (2) the dark mantle in the valley, and (3) the surface material at the North Massif. The dark-mantle soils are chemically similar to those at Tranquillitatis. Basalt samples from the dark mantle are chemically similar although they range from fine to coarse grained. It is suggested that they originated from the same source but crystallized at varying depths from the surface.

Chemical element transport in stellar evolution models

PubMed Central

Cassisi, Santi

2017-01-01

Stellar evolution computations provide the foundation of several methods applied to study the evolutionary properties of stars and stellar populations, both Galactic and extragalactic. The accuracy of the results obtained with these techniques is linked to the accuracy of the stellar models, and in this context the correct treatment of the transport of chemical elements is crucial. Unfortunately, in many respects calculations of the evolution of the chemical abundance profiles in stars are still affected by sometimes sizable uncertainties. Here, we review the various mechanisms of element transport included in the current generation of stellar evolution calculations, how they are implemented, the free parameters and uncertainties involved, the impact on the models and the observational constraints. PMID:28878972

Chemical evolution of the Earth: Equilibrium or disequilibrium process?

NASA Technical Reports Server (NTRS)

Sato, M.

1985-01-01

To explain the apparent chemical incompatibility of the Earth's core and mantle or the disequilibrium process, various core forming mechanisms have been proposed, i.e., rapid disequilibrium sinking of molten iron, an oxidized core or protocore materials, and meteorite contamination of the upper mantle after separation from the core. Adopting concepts used in steady state thermodynamics, a method is devised for evaluating how elements should distribute stable in the Earth's interior for the present gradients of temperature, pressure, and gravitational acceleration. Thermochemical modeling gives useful insights into the nature of chemical evolution of the Earth without overly speculative assumptions. Further work must be done to reconcile siderophile elements, rare gases, and possible light elements in the outer core.

Chemical element transport in stellar evolution models.

PubMed

Salaris, Maurizio; Cassisi, Santi

2017-08-01

Stellar evolution computations provide the foundation of several methods applied to study the evolutionary properties of stars and stellar populations, both Galactic and extragalactic. The accuracy of the results obtained with these techniques is linked to the accuracy of the stellar models, and in this context the correct treatment of the transport of chemical elements is crucial. Unfortunately, in many respects calculations of the evolution of the chemical abundance profiles in stars are still affected by sometimes sizable uncertainties. Here, we review the various mechanisms of element transport included in the current generation of stellar evolution calculations, how they are implemented, the free parameters and uncertainties involved, the impact on the models and the observational constraints.

Micromechanical calorimetric sensor

DOEpatents

Thundat, Thomas G.; Doktycz, Mitchel J.

2000-01-01

A calorimeter sensor apparatus is developed utilizing microcantilevered spring elements for detecting thermal changes within a sample containing biomolecules which undergo chemical and biochemical reactions. The spring element includes a bimaterial layer of chemicals on a coated region on at least one surface of the microcantilever. The chemicals generate a differential thermal stress across the surface upon reaction of the chemicals with an analyte or biomolecules within the sample due to the heat of chemical reactions in the sample placed on the coated region. The thermal stress across the spring element surface creates mechanical bending of the microcantilever. The spring element has a low thermal mass to allow detection and measuring of heat transfers associated with chemical and biochemical reactions within a sample placed on or near the coated region. A second surface may have a different material, or the second surface and body of microcantilever may be of an inert composition. The differential thermal stress between the surfaces of the microcantilever create bending of the cantilever. Deflections of the cantilever are detected by a variety of detection techniques. The microcantilever may be approximately 1 to 200 .mu.m long, approximately 1 to 50 .mu.m wide, and approximately 0.3 to 3.0 .mu.m thick. A sensitivity for detection of deflections is in the range of 0.01 nanometers. The microcantilever is extremely sensitive to thermal changes in samples as small as 30 microliters.

Production of [211At]-Astatinated Radiopharmaceuticals and Applications in Targeted α-Particle Therapy

PubMed Central

Guérard, François; Gestin, Jean-François

2013-01-01

Abstract 211At is a promising radionuclide for α-particle therapy of cancers. Its physical characteristics make this radionuclide particularly interesting to consider when bound to cancer-targeting biomolecules for the treatment of microscopic tumors. 211At is produced by cyclotron irradiation of 209Bi with α-particles accelerated at ∼28 MeV and can be obtained in high radionuclidic purity after isolation from the target. Its chemistry resembles iodine, but there is also a tendency to behave as a metalloid. However, the chemical behavior of astatine has not yet been clearly established, primarily due to the lack of any stable isotopes of this element, which precludes the use of conventional analytical techniques for its characterization. There are also only a limited number of research centers that have been able to produce this element in sufficient amounts to carry out extensive investigations. Despite these difficulties, chemical reactions typically used with iodine can be performed, and a number of biomolecules of interest have been labeled with 211At. However, most of these compounds exhibit unacceptable instability in vivo due to the weakness of the astatine–biomolecule bond. Nonetheless, several compounds have shown high potential for the treatment of cancers in vitro and in several animal models, thus providing a promising basis that has allowed initiation of the first two clinical studies. PMID:23075373

Brown Rice and Its Component, γ-Oryzanol, Attenuate the Preference for High-Fat Diet by Decreasing Hypothalamic Endoplasmic Reticulum Stress in Mice

PubMed Central

Kozuka, Chisayo; Yabiku, Kouichi; Sunagawa, Sumito; Ueda, Rei; Taira, Shin-ichiro; Ohshiro, Hiroyuki; Ikema, Tomomi; Yamakawa, Ken; Higa, Moritake; Tanaka, Hideaki; Takayama, Chitoshi; Matsushita, Masayuki; Oyadomari, Seiichi; Shimabukuro, Michio; Masuzaki, Hiroaki

2012-01-01

Brown rice is known to improve glucose intolerance and prevent the onset of diabetes. However, the underlying mechanisms remain obscure. In the current study, we investigated the effect of brown rice and its major component, γ-oryzanol (Orz), on feeding behavior and fuel homeostasis in mice. When mice were allowed free access to a brown rice–containing chow diet (CD) and a high-fat diet (HFD), they significantly preferred CD to HFD. To reduce hypothalamic endoplasmic reticulum (ER) stress on an HFD, mice were administered with 4-phenylbutyric acid, a chemical chaperone, which caused them to prefer the CD. Notably, oral administration of Orz, a mixture of major bioactive components in brown rice, also improved glucose intolerance and attenuated hypothalamic ER stress in mice fed the HFD. In murine primary neuronal cells, Orz attenuated the tunicamycin-induced ER stress. In luciferase reporter assays in human embryonic kidney 293 cells, Orz suppressed the activation of ER stress–responsive cis-acting elements and unfolded protein response element, suggesting that Orz acts as a chemical chaperone in viable cells. Collectively, the current study is the first demonstration that brown rice and Orz improve glucose metabolism, reduce hypothalamic ER stress, and, consequently, attenuate the preference for dietary fat in mice fed an HFD. PMID:22826028

Capacitively readout multi-element sensor array with common-mode cancellation

DOEpatents

Britton, Jr., Charles L.; Warmack, Robert J.; Bryan, William L.; Jones, Robert L.; Oden, Patrick Ian; Thundat, Thomas

2001-01-01

An improved multi-element apparatus for detecting the presence of at least one chemical, biological or physical component in a monitored area comprising an array or single set of the following elements: a capacitive transducer having at least one cantilever spring element secured thereto, the cantilever element having an area thereof coated with a chemical having an affinity for the component to be detected; a pick-up plate positioned adjacent to the cantilever element at a distance such that a capacitance between the cantilever element and the pick-up plate changes as the distance between the cantilever element and the pick-up plate varies, the change in capacitance being a measurable variation; a detection means for measuring the measurable variation in the capacitance between the cantilever element and the pick-up plate that forms a measurement channel signal; and at least one feedback cantilever spring element positioned apart from the coated cantilever element, the cantilever element substantially unaffected by the component being monitored and providing a reference channel signal to the detection means that achieves a common mode cancellation between the measurement channel signal and reference channel signal.

CHEMICAL MAPPING OF ELEMENTAL SULFUR ON PYRITE AND ARSENOPYRITE SURFACES USING NEAR-INFRARED RAMAN IMAGING MICROSCOPY. (R826189)

EPA Science Inventory

Abstract

Near-infrared Raman imaging microscopy (NIRIM) was used to produce chemical images of the distribution of elemental sulfur on oxidized pyrite and arsenopyrite surfaces. Analysis using Savitsky_¯Golay filtering permits an unambiguous identificati...

Characterizing and Representing Student's Conceptual Knowledge of Chemical Bonding

ERIC Educational Resources Information Center

Yayon, Malka; Mamlok-Naaman, Rachel; Fortus, David

2012-01-01

Chemical bonding knowledge is fundamental and essential to the understanding of almost every topic in chemistry, but it is very difficult to learn. While many studies have characterized some of the central elements of knowledge of this topic, these elements of knowledge have not been systematically organized. We describe the development and…

Simultaneous topographic and elemental chemical and magnetic contrast in scanning tunneling microscopy

DOEpatents

Rose, Volker; Preissner, Curt A; Hla, Saw-Wai; Wang, Kangkang; Rosenmann, Daniel

2014-09-30

A method and system for performing simultaneous topographic and elemental chemical and magnetic contrast analysis in a scanning, tunneling microscope. The method and system also includes nanofabricated coaxial multilayer tips with a nanoscale conducting apex and a programmable in-situ nanomanipulator to fabricate these tips and also to rotate tips controllably.

Profiling Environmental Chemicals for Activity in the Antioxidant Response Element Signaling Pathway Using a High-Throughput Screening Approach

EPA Science Inventory

1 ABSTRACT 2 3 BACKGROUND: Oxidative stress has been implicated in the pathogenesis of a variety 4 of diseases ranging from cancer to neurodegeneration, highlighti.ng the need to identify 5 chemicals that can induce this effect. The antioxidant response element (ARE)...

Application of thermodynamics to silicate crystalline solutions

NASA Technical Reports Server (NTRS)

Saxena, S. K.

1972-01-01

A review of thermodynamic relations is presented, describing Guggenheim's regular solution models, the simple mixture, the zeroth approximation, and the quasi-chemical model. The possibilities of retrieving useful thermodynamic quantities from phase equilibrium studies are discussed. Such quantities include the activity-composition relations and the free energy of mixing in crystalline solutions. Theory and results of the study of partitioning of elements in coexisting minerals are briefly reviewed. A thermodynamic study of the intercrystalline and intracrystalline ion exchange relations gives useful information on the thermodynamic behavior of the crystalline solutions involved. Such information is necessary for the solution of most petrogenic problems and for geothermometry. Thermodynamic quantities for tungstates (CaWO4-SrWO4) are calculated.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lorut, F.; Imbert, G.; Roggero, A.

In this paper, we investigate the tendency of porous low-K dielectrics (also named Ultra Low-K, ULK) behavior to shrink when exposed to the electron beam of a scanning electron microscope. Various experimental electron beam conditions have been used for irradiating ULK thin films, and the resulting shrinkage has been measured through use of an atomic force microscope tool. We report the shrinkage to be a fast, cumulative, and dose dependent effect. Correlation of the shrinkage with incident electron beam energy loss has also been evidenced. The chemical modification of the ULK films within the interaction volume has been demonstrated, withmore » a densification of the layer and a loss of carbon and hydrogen elements being observed.« less

Exact solution of a model DNA-inversion genetic switch with orientational control.

PubMed

Visco, Paolo; Allen, Rosalind J; Evans, Martin R

2008-09-12

DNA inversion is an important mechanism by which bacteria and bacteriophage switch reversibly between phenotypic states. In such switches, the orientation of a short DNA element is flipped by a site-specific recombinase enzyme. We propose a simple model for a DNA-inversion switch in which recombinase production is dependent on the switch state (orientational control). Our model is inspired by the fim switch in E. coli. We present an exact analytical solution of the chemical master equation for the model switch, as well as stochastic simulations. Orientational control causes the switch to deviate from Poissonian behavior: the distribution of times in the on state shows a peak and successive flip times are correlated.

Strong nonlinear photonic responses from microbiologically synthesized tellurium nanocomposites

USGS Publications Warehouse

Liao, K.-S.; Wang, Jingyuan; Dias, S.; Dewald, J.; Alley, N.J.; Baesman, S.M.; Oremland, R.S.; Blau, W.J.; Curran, S.A.

2010-01-01

A new class of nanomaterials, namely microbiologically-formed nanorods composed of elemental tellurium [Te(0)] that forms unusual nanocomposites when combined with poly(m-phenylenevinylene-co-2,5-dioctoxy-phenylenevinylene) (PmPV) is described. These bio-nanocomposites exhibit excellent broadband optical limiting at 532 and 1064 nm. Nonlinear scattering, originating from the laser induced solvent bubbles and microplasmas, is responsible for this nonlinear behavior. The use of bacterially-formed Te(0) when combined with an organic chemical host (e.g., PmPV) is a new green method of nanoparticle syntheses. This opens the possibilities of using unique, biologically synthesized materials to advance future nanoelectronic and nanophotonic applications. ?? 2009 Elsevier B.V. All rights reserved.

Is Pelvic-Floor Muscle Training a Physical Therapy or a Behavioral Therapy? A Call to Name and Report the Physical, Cognitive, and Behavioral Elements.

PubMed

Frawley, Helena C; Dean, Sarah G; Slade, Susan C; Hay-Smith, E Jean C

2017-04-01

This perspective article explores whether pelvic-floor muscle training (PFMT) for the management of female urinary incontinence and prolapse is a physical therapy or a behavioral therapy. The primary aim is to demonstrate that it is both. A secondary aim is to show that the plethora of terms used for PFMT is potentially confusing and that current terminology inadequately represents the full intent, content, and delivery of this complex intervention. While physical therapists may be familiar with exercise terms, the details are often incompletely reported; furthermore, physical therapists are less familiar with the terminology used in accurately representing cognitive and behavioral therapy interventions, which results in these elements being even less well reported. Thus, an additional aim is to provide greater clarity in the terminology used in the reporting of PFMT interventions, specifically, descriptions of the exercise and behavioral elements. First, PFMT is described as a physical therapy and as an exercise therapy informed predominantly by the discipline of physical therapy. However, effective implementation requires use of the cognitive and behavioral perspectives of the discipline of psychology. Second, the theoretical underpinning of the psychology-informed elements of PFMT is summarized. Third, to address some identified limitations and confusion in current terminology and reporting, recommendations for ways in which physical therapists can incorporate the psychology-informed elements of PFMT alongside the more familiar exercise therapy-informed elements are made. Fourth, an example of how both elements can be described and reported in a PFMT intervention is provided. In summary, this perspective explores the underlying concepts of PFMT to demonstrate that it is both a physical intervention and a behavioral intervention and that it can and should be described as such, and an example of the integration of these elements into clinical practice is provided. © 2017 American Physical Therapy Association.

Constitutive Behavior and Finite Element Analysis of FRP Composite and Concrete Members.

PubMed

Ann, Ki Yong; Cho, Chang-Geun

2013-09-10

The present study concerns compressive and flexural constitutive models incorporated into an isoparametric beam finite element scheme for fiber reinforced polymer (FRP) and concrete composites, using their multi-axial constitutive behavior. The constitutive behavior of concrete was treated in triaxial stress states as an orthotropic hypoelasticity-based formulation to determine the confinement effect of concrete from a three-dimensional failure surface in triaxial stress states. The constitutive behavior of the FRP composite was formulated from the two-dimensional classical lamination theory. To predict the flexural behavior of circular cross-section with FRP sheet and concrete composite, a layered discretization of cross-sections was incorporated into nonlinear isoparametric beam finite elements. The predicted constitutive behavior was validated by a comparison to available experimental results in the compressive and flexural beam loading test.

Ontology and modeling patterns for state-based behavior representation

NASA Technical Reports Server (NTRS)

Castet, Jean-Francois; Rozek, Matthew L.; Ingham, Michel D.; Rouquette, Nicolas F.; Chung, Seung H.; Kerzhner, Aleksandr A.; Donahue, Kenneth M.; Jenkins, J. Steven; Wagner, David A.; Dvorak, Daniel L.;

[The determination of the natural content of chemical elements in human biological objects (liver, kidney, stomach) by mass spectrometry with inductively coupled plasma].

PubMed

Luzanova, I S; Svetlolobov, D Iu; Zorin, Iu V

2014-01-01

The objective of the present work was to continue the studies of the sites of concentration of the chemical elements corresponding to normal homeostasis in human biological objects by mass spectrometry with inductively coupled plasma. The study yielded the data on the natural content of 27 elements in the cadaveric liver, kidney, and stomach. It is recommended to use these findings as the reference parameters corresponding to normal homeostasis.

Chemical properties of the transactinide elements studied inliquid phase with SISAK

DOE Office of Scientific and Technical Information (OSTI.GOV)

Omtvedt, J.P.; Alstad, J.; Bjornstad, T.

2007-05-01

This article starts with a review of the current SISAKliquid-liquid extraction system, as used after the physical preseparatorBGS at LBNL for chemical studies of transactinide elements. Emphasis willbe on new additions and developments. Then the possibilities offered bythe new TASCA separator at GSI and the use of actinide targets at bothGSI and LBNL are discussed with respect to future SISAK transactinideexperiments. Finally, current and future liquid-liquid extraction systemsfor studying elements Rf up to Hs are discussed.

Tuning the Spin-Alignment of Interstitial Electrons in Two-Dimensional Y2C Electride via Chemical Pressure.

PubMed

Park, Jongho; Hwang, Jae-Yeol; Lee, Kyu Hyoung; Kim, Seong-Gon; Lee, Kimoon; Kim, Sung Wng

2017-12-06

We report that the spin-alignment of interstitial anionic electrons (IAEs) in two-dimensional (2D) interlayer spacing can be tuned by chemical pressure that controls the magnetic properties of 2D electrides. It was clarified from the isovalent Sc substitution on the Y site in the 2D Y 2 C electride that the localization degree of IAEs at the interlayer becomes stronger as the unit cell volume and c-axis lattice parameter were systematically reduced by increasing the Sc contents, thus eventually enhancing superparamagnetic behavior originated from the increase in ferromagnetic particle concentration. It was also found that the spin-aligned localized IAEs dominated the electrical conduction of heavily Sc-substituted Y 2 C electride. These results indicate that the physcial properties of 2D electrides can be tailored by adjusting the localization of IAEs at interlayer spacing via structural modification that controls the spin instability as found in three-dimensional elemental electrides of pressurized potassium metals.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Yanwen; Jin, Ke; Xue, Haizhou

We report that historically, alloy development with better radiation performance has been focused on traditional alloys with one or two principal element(s) and minor alloying elements, where enhanced radiation resistance depends on microstructural or nanoscale features to mitigate displacement damage. In sharp contrast to traditional alloys, recent advances of single-phase concentrated solid solution alloys (SP-CSAs) have opened up new frontiers in materials research. In these alloys, a random arrangement of multiple elemental species on a crystalline lattice results in disordered local chemical environments and unique site-to-site lattice distortions. Based on closely integrated computational and experimental studies using a novel setmore » of SP-CSAs in a face-centered cubic structure, we have explicitly demonstrated that increasing chemical disorder can lead to a substantial reduction in electron mean free paths, as well as electrical and thermal conductivity, which results in slower heat dissipation in SP-CSAs. The chemical disorder also has a significant impact on defect evolution under ion irradiation. Considerable improvement in radiation resistance is observed with increasing chemical disorder at electronic and atomic levels. Finally, the insights into defect dynamics may provide a basis for understanding elemental effects on evolution of radiation damage in irradiated materials and may inspire new design principles of radiation-tolerant structural alloys for advanced energy systems.« less

Analysis of the FF Aqr spectra

NASA Astrophysics Data System (ADS)

Shimanskaya, N. N.; Bikmaev, I. F.; Shimansky, V. V.

2011-07-01

We determine the atmospheric parameters of the secondary in the close binary system FF Aqr and analyze its chemical composition. A series of high-resolution spectra are taken at different orbital phases using the coude echelle spectrometer of the 1.5-m Russian-Turkish Telescope (RTT150). We show that the absorption line intensity of heavy elements varies with phase due to the spotty nature of the cool component. We determine the abundances of heavy elements in the star's atmosphere by modelling the synthetic spectra and performing a differential analysis of the chemical composition of FF Aqr relative to the solar composition. Our analysis of the averaged spectrum of FF Aqr yielded 539 abundance estimates for 21 chemical elements. We found the metallicity of the star ([ Fe/H] = -0.11 ± 0.08) to be close solar, in agreement with the hypothesis that FF Aqr should belong to the Galactic disk. The inferred chemical composition of the objects exhibits no anomalous abundances of the α-, r-, and s-process elements like those earlier found in other systems (IN Com, LW Hya, V471 Tau). The lack of such anomalies in FF Aqr must be due to the fact that the elements heavier than 16 O cannot be synthesized in the core of the primary during the last stages of its evolution.

Distribution of elements in the Salt Wash member of the Morrison Formation in the Jo Dandy area, Montrose County, Colorado

USGS Publications Warehouse

Newman, William L.; Elston, Donald P.

1957-01-01

A study of the distribution of elements in the Salt Wash member of the Morrison formation of Jurassic age from samples taken in the Jo Dandy area, Montrose County, Colo., was made to determine average chemical composition of mudstone and sandstone and to determine the magnitude of variations in concentrations of elements within similar rock types. Analytical data were obtained by semiquantitative spectrographic and radiometric methods. Results of the study show that variations in concentrations of about 20 elements commonly detected by semiquantititive spectrographic analyses of sedimentary rocks are small for a specific rock type; therefore, considerable confidence may be placed upon the average chemical appears to be no significant relation between chemical composition of mudstone or sandstone and distance from known uranium-vanadium ore or mineralization rock. Mudstone generally contains greater concentrations of the elements studied than sandstone. The chemical composition of red mudstone is similar to the chemical composition of green mudstone except that red mudstone was found to contain almost twice as much calcium as green mudstone in the Jo Dandy area. Samples of the unoxidized sandstone from the Jo Dandy area contain about twice as much calcium, three times as much strontium, but only about one-half as much as zirconium as oxidized sandstone; except for these elements the chemical compositions of both categories of sandstone are similar. Samples of sandstone of the Salt Wash member in the Jo Dandy area contain more potassium, magnesium, vanadium, and nickel than “average sandstone” of the Salt Wash member. The distribution of bismuth in rocks of the Jo Dandy area suggests that bismuth and perhaps part of the potassium and magnesium found in rocks of the Salk Wash member were either derived from solutions which ascended from the underlying salt- and gypsum-bearing Paradox member that was incorporated with rocks of the Salt Wash during sedimentation.

Common Elements for the Psychotherapeutic Management of Patients with Self Injurious Behavior

ERIC Educational Resources Information Center

Schiavone, Francesca L.; Links, Paul S.

2013-01-01

Objectives: Current research suggests that effective psychotherapies for Self Injurious Behavior (SIB) in the context of Borderline Personality Disorder (BPD) contain generic common elements which are responsible for their success. Because of the links between BPD, SIB, and child abuse, it is likely that these common elements can also be applied…

Multiscale Speciation of U and Pu at Chernobyl, Hanford, Los Alamos, McGuire AFB, Mayak, and Rocky Flats.

PubMed

Batuk, Olga N; Conradson, Steven D; Aleksandrova, Olga N; Boukhalfa, Hakim; Burakov, Boris E; Clark, David L; Czerwinski, Ken R; Felmy, Andrew R; Lezama-Pacheco, Juan S; Kalmykov, Stepan N; Moore, Dean A; Myasoedov, Boris F; Reed, Donald T; Reilly, Dallas D; Roback, Robert C; Vlasova, Irina E; Webb, Samuel M; Wilkerson, Marianne P

2015-06-02

The speciation of U and Pu in soil and concrete from Rocky Flats and in particles from soils from Chernobyl, Hanford, Los Alamos, and McGuire Air Force Base and bottom sediments from Mayak was determined by a combination of X-ray absorption fine structure (XAFS) spectroscopy and X-ray fluorescence (XRF) element maps. These experiments identify four types of speciation that sometimes may and other times do not exhibit an association with the source terms and histories of these samples: relatively well ordered PuO2+x and UO2+x that had equilibrated with O2 and H2O under both ambient conditions and in fires or explosions; instances of small, isolated particles of U as UO2+x, U3O8, and U(VI) species coexisting in close proximity after decades in the environment; alteration phases of uranyl with other elements including ones that would not have come from soils; and mononuclear Pu-O species and novel PuO2+x-type compounds incorporating additional elements that may have occurred because the Pu was exposed to extreme chemical conditions such as acidic solutions released directly into soil or concrete. Our results therefore directly demonstrate instances of novel complexity in the Å and μm-scale chemical speciation and reactivity of U and Pu in their initial formation and after environmental exposure as well as occasions of unexpected behavior in the reaction pathways over short geological but significant sociological times. They also show that incorporating the actual disposal and site conditions and resultant novel materials such as those reported here may be necessary to develop the most accurate predictive models for Pu and U in the environment.

A chemical-spectrochemical method for the determination of rare earth elements and thorium in cerium minerals

USGS Publications Warehouse

Rose, H.J.; Murata, K.J.; Carron, M.K.

1954-01-01

In a combined chemical-spectrochemical procedure for quantitatively determining rare earth elements in cerium minerals, cerium is determined volumetrically, a total rare earths plus thoria precipitate is separated chemically, the ceria content of the precipitate is raised to 80??0 percent by adding pure ceria, and the resulting mixture is analyzed for lanthanum, praseodymium, neodymium, samarium, gadolinium, yttrium, and thorium spectrochemically by means of the d.c. carbon arc. Spectral lines of singly ionized cerium are used as internal standard lines in the spectrochemical determination which is patterned after Fassel's procedure [1]. Results of testing the method with synthetic mixtures of rare earths and with samples of chemically analyzed cerium minerals show that the coefficient of variation for a quadruplicate determination of any element does not exceed 5??0 (excepting yttrium at concentrations less than 1 percent) and that the method is free of serious systematic error. ?? 1954.

Versatile protein recognition by the encoded display of multiple chemical elements on a constant macrocyclic scaffold

NASA Astrophysics Data System (ADS)

Li, Yizhou; De Luca, Roberto; Cazzamalli, Samuele; Pretto, Francesca; Bajic, Davor; Scheuermann, Jörg; Neri, Dario

2018-03-01

In nature, specific antibodies can be generated as a result of an adaptive selection and expansion of lymphocytes with suitable protein binding properties. We attempted to mimic antibody-antigen recognition by displaying multiple chemical diversity elements on a defined macrocyclic scaffold. Encoding of the displayed combinations was achieved using distinctive DNA tags, resulting in a library size of 35,393,112. Specific binders could be isolated against a variety of proteins, including carbonic anhydrase IX, horseradish peroxidase, tankyrase 1, human serum albumin, alpha-1 acid glycoprotein, calmodulin, prostate-specific antigen and tumour necrosis factor. Similar to antibodies, the encoded display of multiple chemical elements on a constant scaffold enabled practical applications, such as fluorescence microscopy procedures or the selective in vivo delivery of payloads to tumours. Furthermore, the versatile structure of the scaffold facilitated the generation of protein-specific chemical probes, as illustrated by photo-crosslinking.

Precise Chemical Analyses of Planetary Surfaces

NASA Technical Reports Server (NTRS)

Kring, David; Schweitzer, Jeffrey; Meyer, Charles; Trombka, Jacob; Freund, Friedemann; Economou, Thanasis; Yen, Albert; Kim, Soon Sam; Treiman, Allan H.; Blake, David;

40 CFR 710.3 - Definitions.

Code of Federal Regulations, 2011 CFR

2011-07-01

... of a chemical reaction or occurring in nature, and any chemical element or uncombined radical; except... or in part in chemical reaction(s) used for the intentional manufacture of other chemical substance(s... chemical substance was manufactured and other equipment which is strictly ancillary to the reaction vessel...

The Relationship between Litho-Sequential Stratigraphy, Chemostratigraphy of Khuff Carbonates: Implication for Facies and Paleoenvironmental Recognition and Correlation, Central Saudi Arabia

NASA Astrophysics Data System (ADS)

Abdullatif, Osman; Abdlmutalib, Ammar; Ahmed, Jarrah; Abdelgadir, Mohamed; Adam, Ammar

2017-04-01

The Permian-Triassic Khuff Formation carbonate reservoirs (and equivalents) in the Middle East are estimated to contain about 15-20 % of the world's gas reserves. Excellently exposed outcropping Khuff strata in central Saudi Arabia provide good outcrop equivalents to the Khuff Formation in the subsurface. The Khuff Formation is composed of five members and from bottom to top are Ash Shiqqah, Huqayl, Duhaysan, Midnab and Khartam members. The Carbonates lithofacies dominate with minor terrestrial clastics, and the paleoenvironments vary from terrestrial, sabkha, tidal-intertidal and open marine environments. This study investigates the relationship between lithostratigraphy, sequence stratigraphy and chemostratigraphy by integration of both field and laboratory sedimentological and chemical elements data. The vertical chemical elements profiles along the Khuff members show variations in their chemical elements content with the variation in lithofacies types, staking pattern, depositional and stratigraphic pattern. The chemostratigraphic distribution of the chemical elements also showed variation within and between the Khuff members. There is a general agreement between chemostratigraphic analyses based on vertical profiles and binary cross plots. The Khuff members and their stratigraphic boundaries can be differentiated based on their chemostratigraphic signatures. Moreover, the lithofacies and depositional paleoenvironmental of different Khuff members can be identified based on their chemical element contents. Chemostratigraphic zones or clusters are markedly established indicating different lithofacies and depositional paleoenvironments. Terrestrial, channel, lacustrine, shoreline to open marine carbonate lithofacies, as building blocks of sequence stratigraphy, all may be distinguished based on their chemical signatures. These outcrop analog results might be of significance to lithofacies, paleoenvironmental, stratigraphic identification, classification and correlation of Khuff Formation in the subsurface. The results might also provide guides and application to reservoir Khuff Formation identification, layering and zonation in the subsurface.

Chemical Properties of Elements 99 and 100 [Einsteinium and Fermium

DOE R&D Accomplishments Database

Seaborg, G. T.; Thompson, S. G.; Harvey, B. G.; Choppin, G. R.

1954-07-23

A description of some of the chemical properties and of the methods used in the separations of elements 99 [Einsteinium] and 100 [Fermium] are given. The new elements exhibit the properties expected for the tenth and eleventh actinide elements. Attempts to produce an oxidation state greater than III of element 99 have been unsuccessful. In normal aqueous media only the III state of element 100 appears to exist. The relative spacings of the elution peaks of the new elements in some separations with ion exchange resin columns are the same as the relative spacings of the homologous lanthanide elements. The results of experiments involving cation exchange resins with very concentrated hydrochloric acid eluant show that the new elements, like the earlier actinides, are more strongly complexed than the lanthanides. The new elements also exist partially as anions in concentrated hydrochloric acid, as do earlier actinide elements, and they may be partially separated from each other by means of ion exchange resins. With some eluants interesting reversals of elution positions are observed in the region Bk-Cf-99-100, indicating complex ion formation involving unusual factors.

The influence of carbon, sulfur, and silicon on trace element partitioning in iron alloys

NASA Astrophysics Data System (ADS)

Han, J.; Van Orman, J. A.; Crispin, K. L.; Ash, R. D.

2014-12-01

Non-metallic light elements are important constituents of planetary cores and have a strong influence on the partitioning behavior of trace elements. Planetary cores may contain a wide range of non-metallic light elements, including H, N, S, P, Si, and C. Under highly reducing conditions, such as those that are thought to have pertained during the formation of Mercury's core, Si and C, in addition to sulfur, may be particularly important constituents. Each of these elements may strongly effect and have a different impact on the partitioning behavior of trace elements but their combined effects on trace element partitioning have not been quantified. We investigated the partitioning behavior of more than 25 siderophile trace elements within the Fe-S-C-Si system with varying concentrations of C, S, and Si. The experiments were performed under pressures varying from 1 atm to 2 GPa and temperatures ranging from 1200˚C to 1450˚C. All experiments produced immiscible liquids, one enriched in Si and C, and the other predominantly FeS. We found some highly siderophile elements including Os, Ru, Ir, and Re are much more enriched in Fe-Si-C phase than in Fe-S phase, whereas other trace elements like V, Co, Ag, Hf, and Pb are enriched in S-rich phase. However, not all the trace elements enriched in Fe-Si-C phase are repelled by sulfur. Elements like Re and Ru could have different partitioning trends if sulfur concentration in S-rich phase rises. The partitioning behavior of these trace elements could enhance our understanding of the differentiation of Mercury's core under oxygen-poor conditions.

Chemical composition of vegetation along urbanisation gradients in two European cities.

PubMed

Sæbø, A; Hanslin, H M; Torp, T; Lierhagen, S; Gawronska, H; Dzierzanowski, K; Gawronski, S

2015-03-01

Accumulation of particulate matter (PM) and metals on leaves of three deciduous woody species was studied along urbanisation gradients in Stavanger and Warsaw. Differences between rural and urban sites explained most of the observed variation in leaf chemistry, followed by differences between regions. Highest leaf accumulation of elements was found in Warsaw, but also composition of elements differed between the cities. Overall, species showed similar patterns of element accumulation, but differed in accumulation of specific elements. These differences could in part be explained by differences in epicuticular waxes and PM accumulation. Expected source of elements and their chemical characteristics did not explain the observed accumulation patterns. A better differentiation between elements taken up from soil and air would be required for his. Species specific accumulation of elements has to be taken into consideration using leaf samples for biomonitoring. Copyright © 2015 Elsevier Ltd. All rights reserved.

Influence of an igneous intrusion on the inorganic geochemistry of a bituminous coal from Pitkin County, Colorado

USGS Publications Warehouse

Finkelman, R.B.; Bostick, N.H.; Dulong, F.T.; Senftle, F.E.; Thorpe, A.N.

1998-01-01

Although the effects of igneous dikes on the organic matter in coal have been observed at many localities there is virtually no information on the effects of the intrusions of the inorganic constituents in the coal. Such a study may help to elucidate the behavior of trace elements during in situ gasification of coal and may provide insights into the resources potential for coal and coke affected by the intrusion. To determine the effects of an igneous intrusion on the inorganic chemistry of a coal we used a series of 11 samples of coal and natural coke that had been collected at intervals from 3 to 106 cm from a dike that intruded the bituminous Dutch Creek coal in Pitkin, CO. The samples were chemically analyzed for 66 elements. SEM-EDX and X-ray diffraction analysis were performed on selected samples. Volatile elements such as F, Cl, Hg, and Se are not depleted in the samples (coke and coal) nearest the dike that were exposed to the highest temperatures. Their presence in these samples is likely due to secondary enrichment following volatilization of the elements inherent in the coal. Equilibration with ground water may account for the uniform distribution of Na, B, and Cl. High concentrations of Ca, Mg, Fe, Mn, Sr, and CO2 in the coke region are attributed to the reaction of CO and CO2 generated during the coking of the coal with fluids from the intrusion, resulting in the precipitation of carbonates. Similarly, precipitation of sulfide minerals in the coke zone may account for the relatively high concentrations of Ag, Hg, Cu, Zn, and Fe. Most elements are concentrated at the juncture of the fluidized coke and the thermally metamorphosed coal. Many of the elements enriched in this region (for example, Ga, Ge, Mo, Rb, U, La, Ce, Al, K, and Si) may have been adsorbed on either the clays or the organic matter or on both.Although the effects of igneous dikes on the organic matter in coal have been observed at many localities there is virtually no information on the effects of the intrusions on the inorganic constituents in the coal. Such a study may help to elucidate the behavior of trace elements during in situ gasification of coal and may provide insights into the resource potential of coal and coke affected by the intrusion. To determine the effects of an igneous intrusion on the inorganic chemistry of a coal we used a series of 11 samples of coal and natural coke that had been collected at intervals from 3 to 106 cm from a dike that intruded the bituminous Dutch Creek coal in Pitkin, CO. The samples were chemically analyzed for 66 elements. SEM-EDX and X-ray diffraction analysis were performed on selected samples. Volatile elements such as F, Cl, Hg, and Se are not depleted in the samples (coke and coal) nearest the dike that were exposed to the highest temperatures. Their presence in these samples is likely due to secondary enrichment following volatilization of the elements inherent in the coal. Equilibration with ground water may account for the uniform distribution of Na, B, and Cl. High concentrations of Ca, Mg, Fe, Mn, Sr, and CO2 in the coke region are attributed to the reaction of CO and CO2 generated during the coking of the coal with fluids from the intrusion, resulting in the precipitation of carbonates. Similarly, precipitation of sulfide minerals in the coke zone may account for the relatively high concentrations of Ag, Hg, Cu, Zn, and Fe. Most elements are concentrated at the juncture of the fluidized coke and the thermally metamorphosed coal. Many of the elements enriched in this region (for example, Ga, Ge, Mo, Rb, U, La, Ce, Al, K, and Si) may have been adsorbed on either the clays or the organic matter or on both.

Evidence of Coal-Fly-Ash Toxic Chemical Geoengineering in the Troposphere: Consequences for Public Health.

PubMed

Herndon, J Marvin

2015-08-11

The widespread, intentional and increasingly frequent chemical emplacement in the troposphere has gone unidentified and unremarked in the scientific literature for years. The author presents evidence that toxic coal combustion fly ash is the most likely aerosolized particulate sprayed by tanker-jets for geoengineering, weather-modification and climate-modification purposes and describes some of the multifold consequences on public health. Two methods are employed: (1) Comparison of 8 elements analyzed in rainwater, leached from aerosolized particulates, with corresponding elements leached into water from coal fly ash in published laboratory experiments, and (2) Comparison of 14 elements analyzed in dust collected outdoors on a high-efficiency particulate air (HEPA) filter with corresponding elements analyzed in un-leached coal fly ash material. The results show: (1) the assemblage of elements in rainwater and in the corresponding experimental leachate are essentially identical. At a 99% confidence interval, they have identical means (T-test) and identical variances (F-test); and (2) the assemblage of elements in the HEPA dust and in the corresponding average un-leached coal fly ash are likewise essentially identical. The consequences on public health are profound, including exposure to a variety of toxic heavy metals, radioactive elements, and neurologically-implicated chemically mobile aluminum released by body moisture in situ after inhalation or through transdermal induction.

The uses of synchrotron radiation sources for elemental and chemical microanalysis

USGS Publications Warehouse

Chen, J.R.; Chao, E.C.T.; Minkin, J.A.; Back, J.M.; Jones, K.W.; Rivers, M.L.; Sutton, S.R.

1990-01-01

Synchrotron radiation sources offer important features for the analysis of a material. Among these features is the ability to determine both the elemental composition of the material and the chemical state of its elements. For microscopic analysis synchrotron X-ray fluorescence (SXRF) microprobes now offer spatial resolutions of 10 ??m with minimum detection limits in the 1-10 ppm range depending on the nature of the sample and the synchrotron source used. This paper describes the properties of synchrotron radiation and their importance for elemental analysis, existing synchrotron facilities and those under construction that are optimum for SXRF microanalysis, and a number of applications including the high energy excitation of the K lines of heavy elements, microtomography, and XANES and EXAFS spectroscopies. ?? 1990.

Pb-, Sr- and Nd-Isotopic systematics and chemical characteristics of cenozoic basalts, Eastern China

USGS Publications Warehouse

Peng, Z.C.; Zartman, R.E.; Futa, K.; Chen, D.G.

1986-01-01

Forty-eight Paleogene, Neogene and Quaternary basaltic rocks from northeastern and east-central China have been analyzed for major-element composition, selected trace-element contents, and Pb, Sr and Nd isotopic systematics. The study area lies entirely within the marginal Pacific tectonic domain. Proceeding east to west from the continental margin to the interior, the basalts reveal an isotopic transition in mantle source material and/or degree of crustal interaction. In the east, many of the rocks are found to merge both chemically and isotopically with those previously reported from the Japanese and Taiwan island-arc terrains. In the west, clear evidence exists for component(s) of Late Archean continental lithosphere to be present in some samples. A major crustal structure, the Tan-Lu fault, marks the approximate boundary between continental margin and interior isotopic behaviors. Although the isotopic signature of the western basalts has characteristics of lower-crustal contamination, a subcrustal lithosphere, i.e. an attached mantle keel, is probably more likely to be the major contributor of their continental "flavor". The transition from continental margin to interior is very pronounced for Pb isotopes, although Sr and Nd isotopes also combine to yield correlated patterns that deviate strikingly from the mid-ocean ridge basalt (MORB) and oceanic-island trends. The most distinctive chemical attribute of this continental lithosphere component is its diminished U Pb as reflected in the Pb isotopic composition when compared to sources of MORB, oceanic-island and island-arc volcanic rocks. Somewhat diminished Sm Nd and elevated Rb Sr, especially in comparison to the depleted asthenospheric mantle, are also apparent from the Nd- and Sr-isotopic ratios. ?? 1986.

Estimation of palaeohydrochemical conditions using carbonate minerals

NASA Astrophysics Data System (ADS)

Amamiya, H.; Mizuno, T.; Iwatsuki, T.; Yuguchi, T.; Murakami, H.; Saito-Kokubu, Y.

2014-12-01

The long-term evolution of geochemical environment in deep underground is indispensable research subject for geological disposal of high-level radioactive waste, because the evolution of geochemical environment would impact migration behavior of radionuclides in deep underground. Many researchers have made efforts previously to elucidate the geochemical environment within the groundwater residence time based on the analysis of the actual groundwater. However, it is impossible to estimate the geochemical environment for the longer time scale than the groundwater residence time in this method. In this case, analysis of the chemical properties of secondary minerals are one of useful method to estimate the paleohydrochemical conditions (temperature, salinity, pH and redox potential). In particular, carbonate minerals would be available to infer the long-term evolution of hydrochemical for the following reasons; -it easily reaches chemical equilibrium with groundwater and precipitates in open space of water flowing path -it reflects the chemical and isotopic composition of groundwater at the time of crystallization We reviewed the previous studies on carbonate minerals and geochemical conditions in deep underground and estimated the hydrochemical characteristics of past groundwater by using carbonate minerals. As a result, it was found that temperature and salinity of the groundwater during crystallization of carbonate minerals were evaluated quantitatively. On the other hand, pH and redox potential can only be understood qualitatively. However, it is suggested that the content of heavy metal elements such as manganese, iron and uranium, and rare earth elements in the carbonate minerals are useful indicators for estimating redox potential. This study was carried out under a contract with METI (Ministry of Economy, Trade and Industry) as part of its R&D supporting program for developing geological disposal technology.

Transient Changes in Shallow Groundwater Chemistry During the MSU-ZERT CO2 Injection Experiment

NASA Astrophysics Data System (ADS)

Zheng, L.; Apps, J. A.; Spycher, N.; Birkholzer, J. T.; Kharaka, Y. K.; Thordsen, J. J.; Kakouros, E.; Trautz, R. C.

2009-12-01

The Montana State University Zero Emission Research and Technology (MSU-ZERT) field experiment at Bozeman, Montana, is designed to evaluate atmospheric and near-surface monitoring and detection techniques applicable to the potential leakage of CO2 from deep storage reservoirs. However, the experiment also affords an excellent opportunity to investigate the transient changes in groundwater chemical composition in response to increasing CO2 partial pressures. Between July 9 and August 7, 2008, 300 kg/day of food-grade CO2 was injected into shallow groundwater through a horizontal perforated pipe about 2-2.3 m below the ground surface. Changes in groundwater quality were investigated through comprehensive chemical analyses of 80 water samples taken before, during and following CO2 injection from 10 shallow observation wells located 1-6 m from the injection pipe, and from two distant monitoring wells. Field and laboratory analyses suggest rapid and systematic changes in pH, alkalinity, and conductance, as well as increases in the aqueous concentrations of both major and trace element species. A principal component analysis and independent thermodynamic interpretation of the water quality analyses were conducted. Results were interpreted in conjunction with a mineralogical characterization of the shallow sediments and a review of historical records of the chemical composition of rainfall at neighboring monitoring sites. The interpretation permitted tentative identification of a complex array of adsorption/desorption, ion exchange, precipitation/dissolution, oxidation/reduction and infiltration processes that were operative during the test. Geochemical modeling was conducted using TOUGHREACT to test whether the observed water quality changes were consistent with the hypothesized processes, and very good agreement was obtained with respect to the behavior of both major and trace elements.

Characterization and modeling of a highly-oriented thin film for composite forming

NASA Astrophysics Data System (ADS)

White, K. D.; Sherwood, J. A.

2018-05-01

Ultra High Molecular Weight Polyethylene (UHMWPE) materials exhibit high impact strength, excellent abrasion resistance and high chemical resistance, making them attractive for a number of impact applications for automotive, marine and medical industries. One format of this class of materials that is being considered for the thermoforming process is a highly-oriented extruded thin film. Parts are made using a two-step manufacturing process that involves first producing a set of preforms and then consolidating these preforms into a final shaped part. To assist in the design of the processing parameters, simulations of the preforming and compression molding steps can be completed using the finite element method. Such simulations require material input data as developed through a comprehensive characterization test program, e.g. shear, tensile and bending, over the range of potential processing temperatures. The current research investigates the challenges associated with the characterization of thin, highly-oriented UHMWPE films. Variations in grip type, sample size and testing rates are explored to achieve convergence of the characterization data. Material characterization results are then used in finite element simulations of the tension test to explore element formulations that work well with the mechanical behavior. Comparisons of the results from the material characterization tests to results of simulations of the same test are performed to validate the finite element method parameters and the credibility of the user-defined material model.

Use of chemical mechanical polishing in micromachining

DOEpatents

Nasby, R.D.; Hetherington, D.L.; Sniegowski, J.J.; McWhorter, P.J.; Apblett, C.A.

1998-09-08

A process for removing topography effects during fabrication of micromachines. A sacrificial oxide layer is deposited over a level containing functional elements with etched valleys between the elements such that the sacrificial layer has sufficient thickness to fill the valleys and extend in thickness upwards to the extent that the lowest point on the upper surface of the oxide layer is at least as high as the top surface of the functional elements in the covered level. The sacrificial oxide layer is then polished down and planarized by chemical-mechanical polishing. Another layer of functional elements is then formed upon this new planarized surface. 4 figs.

MSC products for the simulation of tire behavior

NASA Technical Reports Server (NTRS)

Muskivitch, John C.

1995-01-01

The modeling of tires and the simulation of tire behavior are complex problems. The MacNeal-Schwendler Corporation (MSC) has a number of finite element analysis products that can be used to address the complexities of tire modeling and simulation. While there are many similarities between the products, each product has a number of capabilities that uniquely enable it to be used for a specific aspect of tire behavior. This paper discusses the following programs: (1) MSC/NASTRAN - general purpose finite element program for linear and nonlinear static and dynamic analysis; (2) MSC/ADAQUS - nonlinear statics and dynamics finite element program; (3) MSC/PATRAN AFEA (Advanced Finite Element Analysis) - general purpose finite element program with a subset of linear and nonlinear static and dynamic analysis capabilities with an integrated version of MSC/PATRAN for pre- and post-processing; and (4) MSC/DYTRAN - nonlinear explicit transient dynamics finite element program.

An Educational Card Game for Learning Families of Chemical Elements

ERIC Educational Resources Information Center

Mariscal, Antonio Joaquin Franco; Martinez, Jose Maria Oliva; Marquez, Serafin Bernal

2012-01-01

This paper describes an educational card game designed to help high school students (grade 10, 15-16 years old) "understand," as opposed to memorize, the periodic table. The game may also be used to identify different chemical elements found in daily life objects. As an additional value, students learn the names and symbols of the displayed…

Chemical Composition of Rainwater in Córdoba City, Argentina

NASA Astrophysics Data System (ADS)

López, M. L.; Asar, M. L.; Ceppi, S.; Bürgesser, R. E.; Avila, E.

2013-05-01

Sampling and chemical analysis of rainwater has proved to be a useful technique for studying its chemical composition and provides a greater understanding of local and regional dispersion of pollutants and their potential impacts to ecosystems through deposition processes. Samples of rainwater were collected during 2009-2012, in Córdoba city, Argentina. Two kind of sampling were performed: event-specific and sequential. The objective of the first of these was to determine the chemical concentration of the total rain, while the objective of the second one was to analyze the variability of the chemical concentration during an individual rain event. The total volume of each sample was divided in halves. One half was filtered through 0.45 μm membrane filter. After this, all the samples were reduced by evaporation to a final volume of 10 ml. The non-filtered samples were acidified and digested in accordance to the method 3050B of the Environmental Protection Agency (EPA) for acid digestion of sediments. Multi-elemental standard solutions in different concentrations were prepared by adequate dilutions. Gallium was added as an internal standard in all standard solutions and samples. Exactly 5 μL of these solutions were deposited on acrylic supports. When these droplets were dried, Synchrotron Radiation Total Reflection X-Ray Fluorescence technique was used for determining the chemical elements. Spectra were analyzed with the AXIL package for spectrum analysis. Due to the intrinsic characteristics of the total reflection technique, the background of the measurements is significantly reduced and there are no matrix effects, therefore quantification can be obtained from the linear correlation between fluorescence intensity and the concentration of the element of interest. The elements quantified were S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Rb, Sr, and Pb. For all of them a calibration curve was performed in order to quantify their concentrations on the samples. The results show that the average pH in city rainwater was pH=6.5; the elements found in the samples were S, Ca, Cu, Cr, Sr, P, Fe, Mn, Pb, K, Ti, V, Zn and the average concentrations of these elements were below the limits established by World Health Organization for drinking water, and show a high natural variability. The temporal evolution of inorganic ion concentration during rain events was analyzed and the scavenging coefficients were calculated and compared with data from literature. A comparison was made between the rainwater chemical composition and chemical composition in the aerosols scavenging during the rain. This study is the first in Córdoba city to analyze the chemical composition of rainwater and constitute a base for future comparison of variability in pH and elemental composition.

Chemical characteristics and origin of H chondrite regolith breccias

NASA Technical Reports Server (NTRS)

Lipschutz, M. E.; Biswas, S.; Mcsween, H. Y., Jr.

1983-01-01

Petrologic data and contents of Ag, Bi, Cd, Co, Cs, Ga, In, Rb, Se, Te, Tl and Zn-trace elements spanning the volatility/mobility range-in light and dark portions of H chondrite regolith breccias and L chondrite fragmental breccias are reported. The chemical/petrologic characteristics of H chondrite regolith breccias differ from those of nonbrecciated chondrites or fragmental breccias. Petrologic characteristics and at least some trace element contents of H chondrite regolith breccias reflect primary processes; contents of the most volatile/mobile elements may reflect either primary or secondary processing, possibly within layered H chondrite parent object(s). Chemical/petrologic differences existed in different regions of the parent(s). Regoligh formation and gardening and meteoroid compaction were not so severe as to alter compositions markedly.

Environmental health attitudes and behaviors: findings from a large pregnancy cohort study.

PubMed

Barrett, Emily S; Sathyanarayana, Sheela; Janssen, Sarah; Redmon, J Bruce; Nguyen, Ruby H N; Kobrosly, Roni; Swan, Shanna H

2014-05-01

Environmental chemicals are widely found in food and personal care products and may have adverse effects on fetal development. Our aim was to examine women's attitudes about these chemicals and ask whether they try to limit their exposure during pregnancy. A multi-center cohort of women in the first trimester of pregnancy completed questionnaires including items on attitudes and behaviors related to environmental chemicals. Multivariable logistic regression models were used to examine: (1) whether sociodemographic variables predict environmental health attitudes and behaviors; and (2) whether women's attitudes about environmental chemicals affect their lifestyle behaviors, particularly diet and personal care product use. Of the 894 subjects, approximately 60% strongly agreed that environmental chemicals are dangerous and 25% strongly felt they were impossible to avoid. Adjusting for covariates, educated women were more likely to believe that environmental chemicals are dangerous (OR 1.74, 95% CI 1.13, 2.66), and that belief, in turn, was associated with a number of healthy behaviors including choosing organic foods, foods in safe plastics, and chemical-free personal care products, and limiting fast food intake. Younger women were more likely to believe that environmental chemicals are impossible to avoid (OR 1.04, 95% CI 1.00, 1.08). Women's attitudes about environmental chemicals may impact their choices during pregnancy. Overcoming a lack of concern about environmental chemicals, particularly among certain sociodemographic groups, is important for the success of clinical or public health prevention measures. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Environmental health attitudes and behaviors: findings from a large pregnancy cohort study

PubMed Central

Barrett, Emily S.; Sathyanarayana, Sheela; Janssen, Sarah; Redmon, J. Bruce; Nguyen, Ruby H.N.; Kobrosly, Roni; Swan, Shanna H.

2014-01-01

Objective Environmental chemicals are widely found in food and personal care products and may have adverse effects on fetal development. Our aim was to examine women’s attitudes about these chemicals and ask whether they try to limit their exposure during pregnancy. Study design A multi-center cohort of women in the first trimester of pregnancy completed questionnaires including items on attitudes and behaviors related to environmental chemicals. Multivariable logistic regression models were used to examine: (1) whether sociodemographic variables predict environmental health attitudes and behaviors; and (2) whether women’s attitudes about environmental chemicals affect their lifestyle behaviors, particularly diet and personal care product use. Results Of the 894 subjects, approximately 60% strongly agreed that environmental chemicals are dangerous and 25% strongly felt they were impossible to avoid. Adjusting for covariates, educated women were more likely to believe that environmental chemicals are dangerous (OR 1.74, 95% CI 1.13, 2.66), and that belief, in turn, was associated with a number of healthy behaviors including choosing organic foods, foods in safe plastics, and chemical-free personal care products, and limiting fast food intake. Younger women were more likely to believe environmental chemicals are impossible to avoid (OR 1.04, 95% CI 1.00, 1.08). Conclusions Women’s attitudes about environmental chemicals may impact their choices during pregnancy. Overcoming a lack of concern about environmental chemicals, particularly among certain sociodemographic groups, is important for the success of clinical or public health prevention measures. PMID:24647207

Element-ary Development.

ERIC Educational Resources Information Center

Schamp, Homer W., Jr.

1989-01-01

Describes the historic development of the periodic table from the four-element theory to the Lavoisier's table. Presents a table listing the old and new names of chemicals and the Lavoisier's table of elements. Lists two references. (YP)

Prediction of shear critical behavior of high-strength reinforced concrete columns using finite element methods

NASA Astrophysics Data System (ADS)

Alrasyid, Harun; Safi, Fahrudin; Iranata, Data; Chen-Ou, Yu

2017-11-01

This research shows the prediction of shear behavior of High-Strength Reinforced Concrete Columns using Finite-Element Method. The experimental data of nine half scale high-strength reinforced concrete were selected. These columns using specified concrete compressive strength of 70 MPa, specified yield strength of longitudinal and transverse reinforcement of 685 and 785 MPa, respectively. The VecTor2 finite element software was used to simulate the shear critical behavior of these columns. The combination axial compression load and monotonic loading were applied at this prediction. It is demonstrated that VecTor2 finite element software provides accurate prediction of load-deflection up to peak at applied load, but provide similar behavior at post peak load. The shear strength prediction provide by VecTor 2 are slightly conservative compare to test result.

Constitutive Behavior and Finite Element Analysis of FRP Composite and Concrete Members

PubMed Central

Ann, Ki Yong; Cho, Chang-Geun

2013-01-01

The present study concerns compressive and flexural constitutive models incorporated into an isoparametric beam finite element scheme for fiber reinforced polymer (FRP) and concrete composites, using their multi-axial constitutive behavior. The constitutive behavior of concrete was treated in triaxial stress states as an orthotropic hypoelasticity-based formulation to determine the confinement effect of concrete from a three-dimensional failure surface in triaxial stress states. The constitutive behavior of the FRP composite was formulated from the two-dimensional classical lamination theory. To predict the flexural behavior of circular cross-section with FRP sheet and concrete composite, a layered discretization of cross-sections was incorporated into nonlinear isoparametric beam finite elements. The predicted constitutive behavior was validated by a comparison to available experimental results in the compressive and flexural beam loading test. PMID:28788312

The fundamental nature of life as a chemical system: the part played by inorganic elements.

PubMed

Williams, Robert J P

2002-02-01

In this article we show why inorganic metal elements from the environment were an essential part of the origin of living aqueous systems of chemicals in flow. Unavoidably such systems have many closely fixed parameters, related to thermodynamic binding constants, for the interaction of the essential exchangeable inorganic metal elements with both inorganic and organic non-metal materials. The binding constants give rise to fixed free metal ion concentration profiles for different metal ions and ligands in the cytoplasm of all cells closely related to the Irving-Williams series. The amounts of bound elements depend on the organic molecules present as well as these free ion concentrations. This system must have predated coding which is probably only essential for reproductive life. Later evolution in changing chemical environments became based on the development of extra cytoplasmic compartments containing quite different energised free (and bound) element contents but in feed-back communication with the central primitive cytoplasm which changed little. Hence species multiplied late in evolution in large part due to the coupling with the altered inorganic environment.

Chemical Compositions of Kinematically Selected Outer Halo Stars

NASA Astrophysics Data System (ADS)

Zhang, Lan; Ishigaki, Miho; Aoki, Wako; Zhao, Gang; Chiba, Masashi

2009-12-01

Chemical abundances of 26 metal-poor dwarfs and giants are determined from high-resolution and high signal-to-noise ratio spectra obtained with the Subaru/High Dispersion Spectrograph. The sample is selected so that most of the objects have outer-halo kinematics. Self-consistent atmospheric parameters were determined by an iterative procedure based on spectroscopic analysis. Abundances of 13 elements, including α-elements (Mg, Si, Ca, Ti), odd-Z light elements (Na, Sc), iron-peak elements (Cr, Mn, Fe, Ni, Zn), and neutron-capture elements (Y, Ba), are determined by two independent data reduction and local thermodynamic equillibrium analysis procedures, confirming the consistency of the stellar parameters and abundances results. We find a decreasing trend of [α/Fe] with increasing [Fe/H] for the range of -3.5< [Fe/H] <-1, as found by Stephens & Boesgaard. [Zn/Fe] values of most objects in our sample are slightly lower than the bulk of halo stars previously studied. These results are discussed as possible chemical properties of the outer halo in the Galaxy. Based on data collected at the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan.

Reactive transport in a partially molten system with binary solid solution

NASA Astrophysics Data System (ADS)

Jordan, J.; Hesse, M. A.

2017-12-01

Melt extraction from the Earth's mantle through high-porosity channels is required to explain the composition of the oceanic crust. Feedbacks from reactive melt transport are thought to localize melt into a network of high-porosity channels. Recent studies invoke lithological heterogeneities in the Earth's mantle to seed the localization of partial melts. Therefore, it is necessary to understand the reaction fronts that form as melt flows across the lithological interface of a heterogeneity and the background mantle. Simplified melting models of such systems aide in the interpretation and formulation of larger scale mantle models. Motivated by the aforementioned facts, we present a chromatographic analysis of reactive melt transport across lithological boundaries, using theory for hyperbolic conservation laws. This is an extension of well-known linear trace element chromatography to the coupling of major elements and energy transport. Our analysis allows the prediction of the feedbacks that arise in reactive melt transport due to melting, freezing, dissolution and precipitation for frontal reactions. This study considers the simplified case of a rigid, partially molten porous medium with binary solid solution. As melt traverses a lithological contact-modeled as a Riemann problem-a rich set of features arise, including a reacted zone between an advancing reaction front and partial chemical preservation of the initial contact. Reactive instabilities observed in this study originate at the lithological interface rather than along a chemical gradient as in most studies of mantle dynamics. We present a regime diagram that predicts where reaction fronts become unstable, thereby allowing melt localization into high-porosity channels through reactive instabilities. After constructing the regime diagram, we test the one-dimensional hyperbolic theory against two-dimensional numerical experiments. The one-dimensional hyperbolic theory is sufficient for predicting the qualitative behavior of reactive melt transport simulations conducted in two-dimensions. The theoretical framework presented can be extended to more complex and realistic phase behavior, and is therefore a useful tool for understanding nonlinear feedbacks in reactive melt transport problems relevant to mantle dynamics.

Design of Fit-for-Purpose Cement to Restore Cement-Caprock Seal Integrity

NASA Astrophysics Data System (ADS)

Provost, R.

2015-12-01

This project aims to study critical research needs in the area of rock-cement interfaces, with a special focus on crosscutting applications in the Wellbore Integrity Pillar of the SubTER initiative. This study will focus on design and test fit-for-purpose cement formulations. The goals of this project are as follows: 1) perform preliminary study of dispersing nanomaterial admixtures in Ordinary Portland Cement (OPC) mixes, 2) characterize the cement-rock interface, and 3) identify potential high-performance cement additives that can improve sorption behavior, chemical durability, bond strength, and interfacial fracture toughness, as appropriate to specific subsurface operational needs. The work presented here focuses on a study of cement-shale interfaces to better understand failure mechanisms, with particular attention to measuring bond strength at the cement-shale interface. Both experimental testing and computational modeling were conducted to determine the mechanical behavior at the interface representing the interaction of cement and shale of a typical wellbore environment. Cohesive zone elements are used in the finite element method to computationally simulate the interface of the cement and rock materials with varying properties. Understanding the bond strength and mechanical performance of the cement-formation interface is critical to wellbore applications such as sequestration, oil and gas production and exploration and nuclear waste disposal. Improved shear bond strength is an indication of the capability of the interface to ensure zonal isolation and prevent zonal communication, two crucial goals in preserving wellbore integrity. Understanding shear bond strength development and interface mechanics will provide an idea as to how the cement-formation interface can be altered under environmental changes (temperature, pressure, chemical degradation, etc.) so that the previously described objectives can be achieved. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000. SAND #: SAND2015-6523 A

A Study of Chemical Composition of δ Scuti-Type Stars Based on the Observations with the BTA and RTT-150

NASA Astrophysics Data System (ADS)

Galeev, A. I.; Berdnikova, V. M.; Ivanova, D. V.; Kudryavtsev, D. O.; Shimanskaya, N. N.; Shimansky, V. V.; Balashova, M. O.

2017-06-01

The results of a study of a sample of δ Scuti-type stars obtained from the observations with the BTA and RTT-150 are presented. Based on photometric data, we measured and analyzed the fundamental parameters of all the studied stars. For eight stars (for two of them for the first time), the fundamental parameters of the atmospheres (Teff, log g, [Fe/H]) and the chemical composition for 29 elements in the LTE-approximation are received using spectroscopic observations. The chemical composition analysis demonstrates both the solar abundances of chemical elements and the anomalies of chemical composition typical of Am stars in the studied sample of δ Scuti-type stars.

40 CFR 710.3 - Definitions.

Code of Federal Regulations, 2012 CFR

2012-07-01

... whole or in part as a result of a chemical reaction or occurring in nature, and any chemical element or... or in part in chemical reaction(s) used for the intentional manufacture of other chemical substance(s... chemical substance was manufactured and other equipment which is strictly ancillary to the reaction vessel...

40 CFR 710.3 - Definitions.

Code of Federal Regulations, 2013 CFR

2013-07-01

... whole or in part as a result of a chemical reaction or occurring in nature, and any chemical element or... or in part in chemical reaction(s) used for the intentional manufacture of other chemical substance(s... chemical substance was manufactured and other equipment which is strictly ancillary to the reaction vessel...

40 CFR 710.3 - Definitions.

Code of Federal Regulations, 2014 CFR

2014-07-01

... whole or in part as a result of a chemical reaction or occurring in nature, and any chemical element or... or in part in chemical reaction(s) used for the intentional manufacture of other chemical substance(s... chemical substance was manufactured and other equipment which is strictly ancillary to the reaction vessel...

40 CFR 710.3 - Definitions.

Code of Federal Regulations, 2010 CFR

2010-07-01

... of a chemical reaction or occurring in nature, and any chemical element or uncombined radical; except... distribution in commerce, when used to describe an action taken with respect to a chemical substance or mixture... or in part in chemical reaction(s) used for the intentional manufacture of other chemical substance(s...

Just a fad? Gamification in health and fitness apps.

PubMed

Lister, Cameron; West, Joshua H; Cannon, Ben; Sax, Tyler; Brodegard, David

2014-08-04

Gamification has been a predominant focus of the health app industry in recent years. However, to our knowledge, there has yet to be a review of gamification elements in relation to health behavior constructs, or insight into the true proliferation of gamification in health apps. The objective of this study was to identify the extent to which gamification is used in health apps, and analyze gamification of health and fitness apps as a potential component of influence on a consumer's health behavior. An analysis of health and fitness apps related to physical activity and diet was conducted among apps in the Apple App Store in the winter of 2014. This analysis reviewed a sample of 132 apps for the 10 effective game elements, the 6 core components of health gamification, and 13 core health behavior constructs. A regression analysis was conducted in order to measure the correlation between health behavior constructs, gamification components, and effective game elements. This review of the most popular apps showed widespread use of gamification principles, but low adherence to any professional guidelines or industry standard. Regression analysis showed that game elements were associated with gamification (P<.001). Behavioral theory was associated with gamification (P<.05), but not game elements, and upon further analysis gamification was only associated with composite motivational behavior scores (P<.001), and not capacity or opportunity/trigger. This research, to our knowledge, represents the first comprehensive review of gamification use in health and fitness apps, and the potential to impact health behavior. The results show that use of gamification in health and fitness apps has become immensely popular, as evidenced by the number of apps found in the Apple App Store containing at least some components of gamification. This shows a lack of integrating important elements of behavioral theory from the app industry, which can potentially impact the efficacy of gamification apps to change behavior. Apps represent a very promising, burgeoning market and landscape in which to disseminate health behavior change interventions. Initial results show an abundant use of gamification in health and fitness apps, which necessitates the in-depth study and evaluation of the potential of gamification to change health behaviors.

Experiments with the low melting indium-bismuth alloy system

NASA Technical Reports Server (NTRS)

Krepski, Richard P.

1992-01-01

The following is a laboratory experiment designed to create an interest in and to further understanding of materials science. The primary audience for this material is the junior high school or middle school science student having no previous familiarity with the material, other than some knowledge of temperature and the concepts of atoms, elements, compounds, and chemical reactions. The objective of the experiment is to investigate the indium-bismuth alloy system. Near the eutectic composition, the liquidus is well below the boiling point of water, allowing simple, minimal hazard casting experiments. Such phenomena as metal oxidation, formation of intermetallic compound crystals, and an unusual volume increase during solidification could all be directly observed. A key concept for students to absorb is that properties of an alloy (melting point, mechanical behavior) may not correlate with simple interpolation of properties of the pure components. Discussion of other low melting metals and alloys leads to consideration of environmental and toxicity issues, as well as providing some historical context. Wetting behavior can also be explored.

Modulating nanoparticle superlattice structure using proteins with tunable bond distributions

DOE PAGES

McMillan, Janet R.; Brodin, Jeffrey D.; Millan, Jaime A.; ...

2017-01-25

Here, we investigate the use of proteins with tunable DNA modification distributions to modulate nanoparticle superlattice structure. Using Beta-galactosidase (βgal) as a model system, we have employed the orthogonal chemical reactivities of surface amines and thiols to synthesize protein-DNA conjugates with 36 evenly distributed or 8 specifically positioned oligonucleotides. When assembled into crystalline superlattices with AuNPs, we find that the distribution of DNA modifications modulates the favored structure: βgal with uniformly distributed DNA bonding elements results in body-centered cubic crystals, whereas DNA functionalization of cysteines results in AB 2 packing. We probe the role of protein oligonucleotide number and conjugatemore » size on this observation, which revealed the importance of oligonucleotide distribution and number in this observed assembly behavior. These results indicate that proteins with defined DNA-modification patterns are powerful tools to control the nanoparticle superlattices architecture, and establish the importance of oligonucleotide distribution in the assembly behavior of protein-DNA conjugates.« less

Extracellular matrix elasticity and topography: material-based cues that affect cell function via conserved mechanisms

PubMed Central

Janson, Isaac A.; Putnam, Andrew J.

2014-01-01

Chemical, mechanical, and topographic extracellular matrix (ECM) cues have been extensively studied for their influence on cell behavior. These ECM cues alter cell adhesion, cell shape, and cell migration, and activate signal transduction pathways to influence gene expression, proliferation, and differentiation. ECM elasticity and topography, in particular, have emerged as material properties of intense focus based on strong evidence these physical cue can partially dictate stem cell differentiation. Cells generate forces to pull on their adhesive contacts, and these tractional forces appear to be a common element of cells’ responses to both elasticity and topography. This review focuses on recently published work that links ECM topography and mechanics and their influence on differentiation and other cell behaviors, We also highlight signaling pathways typically implicated in mechanotransduction that are (or may be) shared by cells subjected to topographic cues. Finally, we conclude with a brief discussion of the potential implications of these commonalities for cell based therapies and biomaterial design. PMID:24910444

Effects of Some Light Alloying Elements on the Oxidation Behavior of Fe and Ni-Cr Based Alloys During Air Plasma Spraying

NASA Astrophysics Data System (ADS)

Zeng, Zhensu; Kuroda, Seiji; Kawakita, Jin; Komatsu, Masayuki; Era, Hidenori

2010-01-01

The oxidation behavior of iron binary powders with addition of Si (1, 4 wt.%) and B (1, 3 wt.%) and that of a Ni-Cr based alloy powder with Si (4.3 wt.%), B (3.0 wt.%), and C (0.8 wt.%) additions during atmosphere plasma spray (APS) have been investigated. Analysis of the chemical composition and phases of oxides in the captured in-flight particles and deposited coatings was carried out. The results show that the addition of Si and B to iron effectively reduced the oxygen contents in the coatings, especially during the in-flight period at higher particles temperature. Ni-Cr based alloy powder with Si, B, and C additions reduced the oxidation of the base alloys significantly. Preferential oxidation and subsequent vaporization of Si, B, and C from the surface of the sprayed particles are believed to play a major role in controlling oxidation in the APS process.

Corrosion behavior of a superduplex stainless steel in chloride aqueous solution

NASA Astrophysics Data System (ADS)

Dabalà, Manuele; Calliari, Irene; Variola, Alessandra

2004-04-01

Super duplex stainless steels (SDSS) have been widely used as structural materials for chemical plants (especially in those engaged in phosphoric acid production), in the hydrometallurgy industries, and as materials for offshore applications due to their excellent corrosion resistance in chloride environments, compared with other commercial types of ferritic stainless steels. These alloys also possess superior weldability and better mechanical properties than austenitic stainless steels. However, due to their two-phase structure, the nature of which is very dependent on their composition and thermal history, the behavior of SDSS regarding localized corrosion appears difficult to predict, especially in chloride environments. To improve their final properties, the effect of the partition of the alloying elements between the two phases, and the composition and microstructure of each phase are the key to understanding the localized corrosion phenomena of SDSS. This paper concerns the effects of the SDSS microstructure and heat treatment on the SDSS corrosion resistance in aqueous solutions, containing different amounts of NaCl at room temperature.

Identification of Some Zeolite Group Minerals by Application of Artificial Neural Network and Decision Tree Algorithm Based on SEM-EDS Data

NASA Astrophysics Data System (ADS)

Akkaş, Efe; Evren Çubukçu, H.; Akin, Lutfiye; Erkut, Volkan; Yurdakul, Yasin; Karayigit, Ali Ihsan

2016-04-01

Identification of zeolite group minerals is complicated due to their similar chemical formulas and habits. Although the morphologies of various zeolite crystals can be recognized under Scanning Electron Microscope (SEM), it is relatively more challenging and problematic process to identify zeolites using their mineral chemical data. SEMs integrated with energy dispersive X-ray spectrometers (EDS) provide fast and reliable chemical data of minerals. However, considering elemental similarities of characteristic chemical formulae of zeolite species (e.g. Clinoptilolite ((Na,K,Ca)2 -3Al3(Al,Si)2Si13O3612H2O) and Erionite ((Na2,K2,Ca)2Al4Si14O36ṡ15H2O)) EDS data alone does not seem to be sufficient for correct identification. Furthermore, the physical properties of the specimen (e.g. roughness, electrical conductivity) and the applied analytical conditions (e.g. accelerating voltage, beam current, spot size) of the SEM-EDS should be uniform in order to obtain reliable elemental results of minerals having high alkali (Na, K) and H2O (approx. %14-18) contents. This study which was funded by The Scientific and Technological Research Council of Turkey (TUBITAK Project No: 113Y439), aims to construct a database as large as possible for various zeolite minerals and to develop a general prediction model for the identification of zeolite minerals using SEM-EDS data. For this purpose, an artificial neural network and rule based decision tree algorithm were employed. Throughout the analyses, a total of 1850 chemical data were collected from four distinct zeolite species, (Clinoptilolite-Heulandite, Erionite, Analcime and Mordenite) observed in various rocks (e.g. coals, pyroclastics). In order to obtain a representative training data set for each minerals, a selection procedure for reference mineral analyses was applied. During the selection procedure, SEM based crystal morphology data, XRD spectra and re-calculated cationic distribution, obtained by EDS have been used for the characterization of the training set. Consequently, for each zeolite species 250 EDS data (as elemental intensities) used for training and 200 ±50 analyses were tested. Finally, two prediction models were developed. The constructed models with various cross-correlation values (r) yielded an average accuracy of >91% for the best predictions using C5.0 Decision Tree algorithm and back propagation artificial neural network. Despite having similar accuracies, the developed models exhibit different prediction behaviors for some zeolite minerals. The results demonstrate that artificial neural network as a nonlinear tool and decision tree algorithm as a rule based prediction model would be employed to provide considerably efficient and reliable identification/classification of some zeolite minerals regardless of their similar elemental compositions. Keywords: mineral identification; zeolites; energy dispersive spectrometry; artificial neural networks; decision tree.

Effect of alloying elements Al and Ca on corrosion resistance of plasma anodized Mg alloys

NASA Astrophysics Data System (ADS)

Anawati, Asoh, Hidetaka; Ono, Sachiko

2016-04-01

Plasma anodizing is a surface treatment used to form a ceramic-type oxide film on Mg alloys by the application of a high anodic voltage to create intense plasma near the metal surface. With proper selection of the process parameters, the technique can produce high quality oxide with superior adhesion, corrosion resistance, micro-hardness, wear resistance and strength. The effect of alloying element Al on plasma anodizing process of Mg alloys was studied by comparing the anodizing curves of pure Mg, AZ31, and AZ61 alloys while the effect of Ca were studied on AZ61 alloys containing 0, 1, and 2 wt% Ca. Anodizing was performed in 0.5 M Na3PO4 solution at a constant current density of 200 Am-2 at 25°C. Anodic oxide films with lava-like structure having mix composition of amorphous and crystal were formed on all of the alloys. The main crystal form of the oxide was Mg3(PO4)2 as analyzed by XRD. Alloying elements Al and Ca played role in modifying the plasma lifetime during anodization. Al tended to extend the strong plasma lifetime and therefore accelerated the film thickening. The effect of Ca on anodizing process was still unclear. The anodic film thickness and chemical composition were altered by the presence of Ca in the alloys. Electrochemical corrosion test in 0.9% NaCl solution showed that the corrosion behavior of the anodized specimens depend on the behavior of the substrate. Increasing Al and Ca content in the alloys tended to increase the corrosion resistance of the specimens. The corrosion resistance of the anodized specimens improved significantly about two orders of magnitude relative to the bare substrate.

Fertility decline and social service access: reconciling behavioral and medical models.

PubMed

Weinstein, J

1978-01-01

In this summary of fertility literature the author attempts to differentiate between the effects of behavioral and medical models of family planning programs on the fertility rate. This is done by determining the effects of access to social welfare services by assessment of: the function of children within the family life survey conducted in the Cameroons are also used. It was found that 7 interdependent elements of social service are involved: 1) general health care; 2) social security for sick and aged; 3) employment training and opportunities for adults; 4) literacy and education; 5) communication and transportation systems; 6) housing and infrastructure; 7) child care and welfare. The presence of these elements is shown to accompany low fertility while their absence is expressed in high rates of child bearing. These elements are major variables in both the nomological and public policy senses. 2 additional components are knowledge of and favorable attitudes towards effective means of fertility control plus effective mechanical, chemical, or natural means of limiting fertility. The concept of fertility norm and its impact on the fertility rate is explained as being the result of the collective force which social affiliations exert on people to reproduce in a certain way. The "stopping rule" is that which will fulfill the fertility norm. An example of this is a culture which continues child bearing until a son has been born and then controls reproduction after this has happened. Such factors must be considered for family planning programs to succeed in these cultures. Therefore fertility levels are found to be the product of prevailing norms and technical ability to achieve these norms. Improvement in levels of access to social services can bring about the lowering of these norms.

Abundance of Chemical Elements in RR Lyrae Variables and their Kinematic Parameters

NASA Astrophysics Data System (ADS)

Gozha, M. L.; Marsakov, V. A.; Koval', V. V.

2018-03-01

A catalog of the chemical and spatial-kinematic parameters of 415 RR Lyrae variables (Lyrids) in the galactic field is compiled. Spectroscopic determinations of the relative abundances of 13 chemical elements in 101 of the RR Lyrae variables are collected from 25 papers published between 1995 and 2017. The data from different sources are reduced to a single solar abundance scale. The mean weighted chemical abundances are calculated with coefficients inversely proportional to the reported errors. An analysis of the deviations in the published relative abundances in each star from the mean square values calculated from them reveals an absence of systematic biases among the results from the various articles. The rectangular coordinates of 407 of the RR Lyrae variables and the components of the three-dimensional (3D) velocities of 401 of the stars are calculated using data from several sources. The collected data on the abundances of chemical elements produced by various nuclear fusion processes for the RR Lyrae variables of the field, as well as the calculated 3D velocities, can be used for studying the evolution of the Galaxy.

Chemical Abundances of Hydrostatic and Explosive Alpha-elements in Sagittarius Stream Stars

NASA Astrophysics Data System (ADS)

Carlin, Jeffrey L.; Sheffield, Allyson A.; Cunha, Katia; Smith, Verne V.

2018-05-01

We analyze chemical abundances of stars in the Sagittarius (Sgr) tidal stream using high-resolution Gemini+GRACES spectra of 42 members of the highest surface-brightness portions of both the trailing and leading arms. Targets were chosen using a 2MASS+WISE color–color selection, combined with the Large Sky Area Multi-Object Fibre Spectroscopic Telescope (LAMOST) radial velocities. In this Letter, we analyze [Fe/H] and α-elements produced by both hydrostatic (O, Mg) and explosive (Si, Ca, Ti) nucleosynthetic processes. The average [Fe/H] for our Sgr stream stars is lower than that for stars in the Sgr core, and stars in the trailing and leading arms show systematic differences in [Fe/H]. Both hydrostatic and explosive elements are depleted relative to Milky Way (MW) disk and halo stars, with a larger gap between the MW trend and Sgr stars for the hydrostatic elements. Chemical abundances of Sgr stream stars show similar patterns to those measured in the core of the Sgr dSph. We explore the ratio of hydrostatic to explosive α-elements [α h/ex] (which we refer to as the “HEx ratio”). Our observed HEx ratio trends for Sgr debris are deficient relative to MW stars. Via simple chemical evolution modeling, we show that these HEx ratio patterns are consistent with a Sgr IMF that lacks the most massive stars. This study provides a link between the chemical properties in the intact Sgr core and the significant portion of the Sgr system’s luminosity that is estimated to currently reside in the streams.

Nanofluidic structures for coupled sensing and remediation of toxins

NASA Astrophysics Data System (ADS)

Shaw, K.; Contento, N. M.; Xu, Wei; Bohn, P. W.

2014-05-01

One foundational motivation for chemical sensing is that knowledge of the presence and level of a chemical agent informs decisions about treatment of the agent, for example by sequestration, separation or chemical conversion to a less harmful substance. Commonly the sensing and treatment steps are separate. However, the disjoint detection/treatment approach is neither optimal, nor required. Thus, we are investigating how nanostructured architectures can be constructed so that molecular transport (analyte/reagent delivery), chemical sensing (optical or electrochemical) and subsequent treatment can all be coupled in the same physical space during the same translocation event. Chemical sensors that are uniquely well-poised for integration into 3-D micro-/nanofluidic architectures include those based on plasmonics and impedance. Following detection, treatment can be substantially enhanced if mass transport limitations can be overcome. In this context, in situ generation of reactive species within confined geometries, such as nanopores or nanochannels, is of significant interest, because of its potential utility in overcoming mass transport limitations in chemical reactivity. Solvent electrolysis in electrochemically coupled nanochannels supporting electrokinetic flow for the generation of reactive species, can produce arbitrarily tunable quantities of reagents, such as O2 or H2, in situ in close proximity to the site of a hydrogenation catalyst, for example. Semi-quantitative estimates of the local H2 concentration are obtained by comparing the spatiotemporal fluorescence behavior and current measurements with finite element simulations accounting for electrolysis and subsequent convection and diffusion within the confined geometry. H2 saturation can easily be achieved at modest overpotentials.

Inhomogeneous chemical evolution of r-process elements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wehmeyer, B., E-mail: benjamin.wehmeyer@unibas.ch; Thielemann, F.-K.; Pignatari, M.

2016-06-21

We report the results of a galactic chemical evolution (GCE) study for r-process- and alpha elements. For this work, we used the inhomogeneous GCE model ”ICE”, which allows to keep track of the galactic abundances of elements produced by different astrophysical sites. The main input parameters for this study were: a) The Neutron Star Merger (NSM) coalescence time scale, the probability of NSMs, and for the sub-class of ”magneto-rotationally driven Supernovae” (”Jet-SNe”), their occurence rate in comparison to ”standard” Supernovae (SNe).

Conversion of the trace elements Zn, Cd, and Pb in the combustion of near-Moscow coals

DOE Office of Scientific and Technical Information (OSTI.GOV)

E.V. Samuilov; L.N. Lebedeva; L.S. Pokrovskaya

A model for the conversion of trace elements in the combustion of near-Moscow coals based on a complex approach combining the capabilities of geochemistry, chemical thermodynamics, phase analysis, and chemical kinetics is proposed. The conversion of the trace elements Zn, Cd, and Pb as the constituents of near-Moscow coal in the flow of coal combustion products along the line of the P-59 boiler at the Ryazanskaya Thermal Power Plant was calculated. Experimental data were used in the development of the model and in calculations.

The Galactic Chemical Evolution of r-Process Elements by Neutron Star Mergers

NASA Astrophysics Data System (ADS)

Komiya, Yutaka; Shigeyama, Toshikazu

Neutron star mergers (NSMs) are prime candidate sources of r-process elements in the universe but it have been said that NSMs cannot reproduce r-process elements on extremely metal-poor (EMP) stars. We revisit this problem using a new chemical evolution model with merger trees of galaxies. We consider (1) propagation of NSM ejecta of kilo-parsec scale due to its very large velocity and (2) star formation efficiency depending on the galaxy mass. In our model with these ingredients, NSMs can successfully reproduce the abundance distribution of EMP stars.

Extraction of information from major element chemical analyses of lunar basalts

NASA Technical Reports Server (NTRS)

Butler, J. C.

1985-01-01

Major element chemical analyses often form the framework within which similarities and differences of analyzed specimens are noted and used to propose or devise models. When percentages are formed the ratios of pairs of components are preserved whereas many familiar statistical and geometrical descriptors are likely to exhibit major changes. This ratio preserving aspect forms the basis for a proposed framework. An analysis of compositional variability within the data set of 42 major element analyses of lunar reference samples was selected to investigate this proposal.

Real World of Industrial Chemistry: Technology of the Rare Earths.

ERIC Educational Resources Information Center

Kremers, Howard E.

1985-01-01

The 17 rare earth elements account for one-fifth of the 83 naturally occurring elements and collectively rank as the 22nd most abundant "element." Properties of these elements (including their chemical similarity), their extraction from the earth, and their uses are discussed. (JN)

Sorption behavior of Eu(III) from an aqueous solution onto modified hydroxyapatite: kinetics, modeling and thermodynamics.

PubMed

Gad, H M H; Youssef, M A

2017-08-16

Nano-pore hydroxyapatite (HAP) was prepared using physical activation of raw and chemically modified [using Acid; HNO 3 (HAPA) or Base; NaOH (HAPB)] bone char (BC) by heating at 900°C for 1 hr to obtain HAP9, HAPA9 and HAPB9, respectively. Investigation the effects of thermal and chemical treatment of prepared nano-hydroxyapatite on elemental analysis, FTIR, scanning electron microscopy, surface area and consequently, the sorption behavior of Eu (III) ions onto the prepared nano-pore hydroxyapatite. Batch adsorption technique was used and the obtained results revealed that the optimum pH = 5.0. The % removal of europium (III) using HAPA9 and HAPB9 reach to 100% within 15 min, while HAP9 after 180 min and the pseudo-second-order was found to be fit to the experimental data. According to Langmuir model, the maximum sorption capacities (q m ) were 123.8, 384.9 and 74.2 mg g -1 for HAP9, HAPA9 and HAPB9, respectively. The reaction is spontaneous according to ΔG° value. HCl (0.5 M) was the most efficient desorbing agent for recovery of Eu(III) and regeneration of adsorbents. Finally, nano-pore hydroxyapatite (HAP) was low cost and very effective adsorbent for sorption or recovery of Eu(III) from aqueous solutions and remediation of environmental pollution.

IUPAC Periodic Table of Isotopes for the Educational Community

DOE Office of Scientific and Technical Information (OSTI.GOV)

Holden N. E.; Holden,N.E.; Coplen,T.B.

2012-07-15

John Dalton first proposed the concept of atomic weights of the elements in the first decade of the nineteenth century. These atomic weights of the chemical elements were thought of as constants of nature, similar to the speed of light. Dmitri Mendeleev arranged the atomic weights of the elements in ascending order of value and used the systematic variation of their chemical properties to produce his Periodic Table of the Elements in 1869. Measurement of atomic weight values became an important chemical activity for a century and a half. Theodore Richards received a Noble Prize for his work in thismore » area. In 1913, Fredrick Soddy found a species of radium, which had an atomic weight value of 228, compared to the familiar radium gas value of 226. Soddy coined the term 'isotope' (Greek for 'in the same place') to account for this second atomic weight value in the radium position of the Periodic Table. Both of these isotopes of radium are radioactive. Radioactive isotopes are energetically unstable and will decay (disintegrate) over time. The time it takes for one half of a sample of a given radioactive isotope to decay is the half-life of that isotope. In addition to having different atomic weight values, radium-226 and radium-228 also have different half-life values. Around the same time as Soddy's work, J.J. Thomson (discoverer of the electron) identified two stable (non-radioactive) isotopes of the same element, neon. Over the next 40 years, the majority of the known chemical elements were found to have two or more stable (or long-lived radioactive isotopes that contribute significantly to the determination of the atomic weights of the elements).« less

Tailoring the physical properties of Ni-based single-phase equiatomic alloys by modifying the chemical complexity

DOE PAGES

Jin, Ke; Sales, Brian C.; Stocks, George Malcolm; ...

2016-02-01

We discovered that equiatomic alloys (e.g. high entropy alloys) have recently attracted considerable interest due to their exceptional properties, which might be closely related to their extreme disorder induced by the chemical complexity. To understand the effects of chemical complexity on their fundamental physical properties, a family of (eight) Ni-based, face-center-cubic (FCC), equiatomic alloys, extending from elemental Ni to quinary high entropy alloys, has been synthesized, and their electrical, thermal, and magnetic properties are systematically investigated in the range of 4–300 K by combining experiments with ab initio Korring-Kohn-Rostoker coherent-potential-approximation (KKR-CPA) calculations. The scattering of electrons is significantly increased duemore » to the chemical (especially magnetic) disorder. It has weak correlation with the number of elements but strongly depends on the type of elements. Thermal conductivities of the alloys are largely lower than pure metals, primarily because the high electrical resistivity suppresses the electronic thermal conductivity. Moreover, the temperature dependence of the electrical and thermal transport properties is further discussed, and the magnetization of five alloys containing three or more elements is measured in magnetic fields up to 4 T.« less

Foreword [Special Issue on Superheavy Elements

DOE PAGES

Düllmann, Christoph E.; Herzberg, Rolf -Dietmar; Nazarewicz, Witold; ...

2015-12-07

Reflecting the breadth of research opportunities in the field of superheavy element research, this special issue covers the range of topics in a comprehensive way, including synthesis of superheavy isotopes, nuclear structure, atomic shell structure, and chemical properties. The contributions detail the status of the field and lay out perspectives for the future. The prospects are bright: new isotopes are awaiting discovery, completing the landscape of superheavy nuclei and bridging the currently existing gap between nuclei synthesized in cold fusion reactions and those from 48Ca induced fusion reactions. The possibility that the limits of nuclear structure studies can be pushedmore » even further in mass and charge has greatly motivated a number of new facilities. Advances in experimental techniques will allow studies on isotopes produced significantly below the 1 pb level. Chemical studies progressing to elements never studied to date are already being prepared. Ultra-fast chemistry setups are under development and it will be fascinating to see them at work, elucidating the influence of relativistic effects on superheavy elements. The richness of chemical systems available for transactinides will expand further, giving access to new chemical systems, giving more information on the architecture of the periodic table.« less

Beyond dichotomies-(m)others' structuring and the development of toddlers' prosocial behavior across cultures.

PubMed

Kärtner, Joscha

2018-04-01

Basic elements of prosociality-(pro)social cognition, motivation, and prosocial behavior-emerge during the first and second year of life. These elements are rooted in biological predispositions and the developmental system is complemented by caregivers' structuring. By structuring, (m)others integrate toddlers' unrefined (pro)social sentiments and behavioral inclinations into coherent patterns and align toddlers' experience and behavior with the population's cultural model. These cultural models specify target states for appropriate affective, motivational and behavioral responses regarding toddlers' prosociality and these target states, in turn, inform (m)others' appraisal and guide their structuring. The experiences that toddlers make in these social interactions have important implications for how the basic elements of prosociality are refined and further develop. Copyright © 2017 Elsevier Ltd. All rights reserved.

Trace element behavior in hydrothermal experiments: Implications for fluid processes at shallow depths in subduction zones

NASA Astrophysics Data System (ADS)

You, C.-F.; Castillo, P. R.; Gieskes, J. M.; Chan, L. H.; Spivack, A. J.

1996-05-01

Chemical evaluation of fluids affected during progressive water-sediment interactions provides critical information regarding the role of slab dehydration and/or crustal recycling in subduction zones. To place some constraints on geochemical processes during sediment subduction, reactions between décollement sediments and synthetic NaCl-CaCl 2 solutions at 25-350°C and 800 bar were monitored in laboratory hydrothermal experiments using an autoclave apparatus. This is the first attempt in a single set of experiments to investigate the relative mobilities of many subduction zone volatiles and trace elements but, because of difficulties in conducting hydrothermal experiments on sediments at high P-T conditions, the experiments could only be designed for a shallow (˜ 10 km) depth. The experimental results demonstrate mobilization of volatiles (B and NH 4) and incompatible elements (As, Be, Cs, Li, Pb, Rb) in hydrothermal fluids at relatively low temperatures (˜ 300°C). In addition, a limited fractionation of light from heavy rare earth elements (REEs) occurs under hydrothermal conditions. On the other hand, the high field strength elements (HFSEs) Cr, Hf, Nb, Ta, Ti, and Zr are not mobile in the reacted fluids. The observed behavior of volatiles and trace elements in hydrothermal fluids is similar to the observed enrichment in As, B, Cs, Li, Pb, Rb, and light REEs and depletion in HFSEs in arc magmas relative to magmas derived directly from the upper mantle. Thus, our work suggests a link between relative mobilities of trace elements in hydrothermal fluids and deep arc magma generation in subduction zones. The experimental results are highly consistent with the proposal that the addition of subduction zone hydrous fluids to the subarc mantle, which has been depleted by previous melting events, can produce the unique characteristics of arc magmas. Moreover, the results suggest that deeply subducted sediments may no longer have the composition necessary to generate the other distinct characteristics, such as the B-δ 11 B and B- 10Be systematics, of arc lavas. Finally, the mobilization of B, Cs, Pb, and light REEs relative to heavy REEs in the hydrothermal fluids fractionate the ratios of B/Be, B/Nb, Cs/Rb, Pb/Ce, La/Ba and LREE/HREE, which behave conservatively during normal magmatic processes. These results demonstrate that the composition of slab-derived fluids has great implications for the recycling of elements; not only in arc magmas but also in mantle plumes.

Precopulatory behavior and sexual conflict in the desert locust

PubMed Central

Golov, Yiftach; Rillich, Jan; Harari, Ally

2018-01-01

Studies of mating and reproductive behavior have contributed much to our understanding of various animals’ ecological success. The desert locust, Schistocerca gregaria, is an important agricultural pest. However, knowledge of locust courtship and precopulatory behavior is surprisingly limited. Here we provide a comprehensive study of the precopulatory behavior of both sexes of the desert locust in the gregarious phase, with particular emphasis on the conflict between the sexes. Detailed HD-video monitoring of courtship and mating of 20 locust pairs, in a controlled environment, enabled both qualitative and quantitative descriptions of the behavior. A comprehensive list of behavioral elements was used to generate an eight-step ethogram, from first encounter between the sexes to actual copulation. Further analyses included the probability of each element occurring, and a kinematic diagram based on a transitional matrix. Eleven novel behavioral elements are described in this study, and two potential points of conflict between the sexes are identified. Locust sexual interaction was characterized by the dominance of the males during the pre-mounting stage, and an overall stereotypic male courtship behavior. In contrast, females displayed no clear courtship-related behavior and an overall less organized behavioral sequence. Central elements in the sexual behavior of the females were low-amplitude hind-leg vibration, as well as rejecting males by jumping and kicking. Intricate reciprocal interactions between the sexes were evident mostly at the mounting stage. The reported findings contribute important insights to our knowledge of locust mating and reproductive behavior, and may assist in confronting this devastating agricultural pest. PMID:29507823

Periodic Table of Elements: Los Alamos National Laboratory

Science.gov Websites

, Communication Specialist talks about the Periodic Table of Elements 7/17/17 Back to Elements List Seaborgium is Phone Periodic Table of Elements: LANL Chemistry Division » Periodic Table of Elements Chemistry the Elements Chemical Properties Elements List Periodic Table Download News LANL Biofuels Work

What more do we need to know for a world without violence?

PubMed

Ercan, Oya; Baltas, Zuhal; Tuzun, Umran; Alikasifoglu, Mujgan

2007-01-01

Violence, a universal health issue, presents serious implications for general health and interpersonal relations. Roots of violence appear in early childhood and instances of extreme violence may become apparent in adolescence. Serious antisocial behavior in adolescence is a predictor of violence in later age. Risk factors for violent behavior could be categorized as individual and environmental. Environmental risk factors can be familial, social, and chemical environmental. Maltreatment in childhood is an important predictor of violent behavior in later age. The presence of mental illness is another important predictor of violence. Contemporary television has a visual and auditory power to promote violence with all its elements. Computers are another field where children confront violence. For identification of individuals who have an increased propensity or susceptibility, for violent behavior, research has suggested that polymorphisms related to certain genes might be important. However, we should emphasize that the expression of such behavior would always depend on interactions between various genes, environmental factors, and genetic-environmental interactions. Experiments in rhesus monkeys have shown that optimal early social experiences might overcome the deleterious effects of susceptible alleles. The effective prevention of violence should consist of interventions that aim to reduce the number of risk factors during early childhood, such as home visitation programs and giving individuals the skills and opportunities for engaging in positive behaviors during school years and adolescence, coupled with the identification of new barriers and reassessment of needs.

Chemical abrasion-SIMS (CA-SIMS) U-Pb dating of zircon from the late Eocene Caetano caldera, Nevada

USGS Publications Warehouse

Watts, Kathryn E.; Coble, Matthew A.; Vazquez, Jorge A.; Henry, Christopher D.; Colgan, Joseph P.; John, David A.

2016-01-01

Zircon geochronology is a critical tool for establishing geologic ages and time scales of processes in the Earth's crust. However, for zircons compromised by open system behavior, achieving robust dates can be difficult. Chemical abrasion (CA) is a routine step prior to thermal ionization mass spectrometry (TIMS) dating of zircon to remove radiation-damaged parts of grains that may have experienced open system behavior and loss of radiogenic Pb. While this technique has been shown to improve the accuracy and precision of TIMS dating, its application to high-spatial resolution dating methods, such as secondary ion mass spectrometry (SIMS), is relatively uncommon. In our efforts to U-Pb date zircons from the late Eocene Caetano caldera by SIMS (SHRIMP-RG: sensitive high resolution ion microprobe, reverse geometry), some grains yielded anomalously young U-Pb ages that implicated Pb-loss and motivated us to investigate with a comparative CA and non-CA dating study. We present CA and non-CA 206Pb/238U ages and trace elements determined by SHRIMP-RG for zircons from three Caetano samples (Caetano Tuff, Redrock Canyon porphyry, and a silicic ring-fracture intrusion) and for R33 and TEMORA-2 reference zircons. We find that non-CA Caetano zircons have weighted mean or bimodal U-Pb ages that are 2–4% younger than CA zircons for the same samples. CA Caetano zircons have mean U-Pb ages that are 0.4–0.6 Myr older than the 40Ar/39Ar sanidine eruption age (34.00 ± 0.03 Ma; error-weighted mean, 2σ), whereas non-CA zircons have ages that are 0.7–1.3 Myr younger. U-Pb ages do not correlate with U (~ 100–800 ppm), Th (~ 50–300 ppm) or any other measured zircon trace elements (Y, Hf, REE), and CA and non-CA Caetano zircons define identical trace element ranges. No statistically significant difference in U-Pb age is observed for CA versus non-CA R33 or TEMORA-2 zircons. Optical profiler measurements of ion microprobe pits demonstrate consistent depths of ~ 1.6 μm for CA and non-CA Caetano, R33 and TEMORA-2 zircons, and do not indicate variations in secondary ion sputtering rates due to chemical or structural changes from the CA treatment. Our new data underscore the potential for cryptic Pb-loss to go unrecognized in other geologically young magmatic centers that do not have zircons with high U, statistically discordant isotope ratios, high common Pb, or metamict textures.

Effect of Heat Treatment on Chemical Segregation in CMSX-4 Nickel-Base Superalloy

NASA Astrophysics Data System (ADS)

Szczotok, A.; Chmiela, B.

2014-08-01

Superalloys display a strong tendency toward chemical segregation during solidification. Therefore, it is of great importance to develop appropriate techniques for the melting and casting of superalloys. Elements partitioning between the γ and γ' phases in single crystal superalloys have been investigated by several authors using electron probe microanalysis (Hemmersmeier and Feller-Kniepmeier Mater Sci Eng A 248:87-97, 1998; Kearsey et al. Intermetallics 12:903-910, 2004; Kearsey et al. Superalloys 2004, pp 801-810, 2004; D'Souza et al. Mater Sci Eng A 490:258-265, 2008). We examined the effect of the particular stages of standard heat treatment (solution treatment and ageing) applied to CMSX-4 single crystal superalloy on chemical segregation that occurs between dendrites and interdendritic areas. Dendritic structures were observed using a scanning electron microscope. Analyses of the chemical composition were performed using energy dispersive x-ray spectroscopy. The obtained qualitative and quantitative results for the concentrations of elements enabled us to confirm the dendritic segregation in as-cast CMSX-4 superalloy. The concentrations of some refractory elements (tungsten, rhenium) were much greater in dendrites than in interdendritic areas. However, these differences in chemical composition gradually decreased during heat treatment. The results obtained in this study warrant further examination of the diffusion processes of elements during heat treatment of the investigated superalloy, and of the kinetics of diffusion.

Determination of element affinities by density fractionation of bulk coal samples

USGS Publications Warehouse

Querol, X.; Klika, Z.; Weiss, Z.; Finkelman, R.B.; Alastuey, A.; Juan, R.; Lopez-Soler, A.; Plana, F.; Kolker, A.; Chenery, S.R.N.

2001-01-01

A review has been made of the various methods of determining major and trace element affinities for different phases, both mineral and organic in coals, citing their various strengths and weaknesses. These include mathematical deconvolution of chemical analyses, direct microanalysis, sequential extraction procedures and density fractionation. A new methodology combining density fractionation with mathematical deconvolution of chemical analyses of whole coals and their density fractions has been evaluated. These coals formed part of the IEA-Coal Research project on the Modes of Occurrence of Trace Elements in Coal. Results were compared to a previously reported sequential extraction methodology and showed good agreement for most elements. For particular elements (Be, Mo, Cu, Se and REEs) in specific coals where disagreement was found, it was concluded that the occurrence of rare trace element bearing phases may account for the discrepancy, and modifications to the general procedure must be made to account for these.

Isotope-abundance variations and atomic weights of selected elements: 2016 (IUPAC Technical Report)

USGS Publications Warehouse

Coplen, Tyler B.; Shrestha, Yesha

2016-01-01

There are 63 chemical elements that have two or more isotopes that are used to determine their standard atomic weights. The isotopic abundances and atomic weights of these elements can vary in normal materials due to physical and chemical fractionation processes (not due to radioactive decay). These variations are well known for 12 elements (hydrogen, lithium, boron, carbon, nitrogen, oxygen, magnesium, silicon, sulfur, chlorine, bromine, and thallium), and the standard atomic weight of each of these elements is given by IUPAC as an interval with lower and upper bounds. Graphical plots of selected materials and compounds of each of these elements have been published previously. Herein and at the URL http://dx.doi.org/10.5066/F7GF0RN2, we provide isotopic abundances, isotope-delta values, and atomic weights for each of the upper and lower bounds of these materials and compounds.

Behavioral changes in young and adult rats: Indications of cholinesterase inhibition

EPA Science Inventory

Inhibition of acetylcholinesterase (AChE) has long been accepted as the basis for neurotoxicity produced by organophosphorus (OP) and N-methyl carbamate chemicals. Functional or behavioral alterations result from acute exposure to these chemicals. We have conducted behavioral eva...

Behavioral changes in adult and young rats as indications of cholinesterase inhibition

EPA Science Inventory

Inhibition of acetylcholinesterase has long been accepted as the basis for neurotoxicity produced by organophosphorus (OP) and N-methyl carbamate chemicals. Functional or behavioral alterations result from acute exposure to these chemicals. We have evaluated behavioral changes an...

Studies on the Behavior of Larval Zebrafish for Developmental Neurotoxicity Screening

EPA Science Inventory

The U.S. Environmental Protection Agency is evaluating methods to screen and prioritize large numbers of chemicals for developmental toxicity. We are exploring methods to detect developmentally neurotoxic chemicals using zebrafish behavior at 6 days of age. The behavioral paradig...

40 CFR 721.10068 - Elemental mercury.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Elemental mercury. 721.10068 Section... Substances § 721.10068 Elemental mercury. (a) Barometer means an instrument used in various applications to... uses subject to reporting. (1) The chemical substance elemental mercury (CAS. No. 7439-97-6) is subject...

40 CFR 721.10068 - Elemental mercury.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Elemental mercury. 721.10068 Section... Substances § 721.10068 Elemental mercury. (a) Barometer means an instrument used in various applications to... uses subject to reporting. (1) The chemical substance elemental mercury (CAS. No. 7439-97-6) is subject...

40 CFR 721.10068 - Elemental mercury.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Elemental mercury. 721.10068 Section... Substances § 721.10068 Elemental mercury. (a) Barometer means an instrument used in various applications to... uses subject to reporting. (1) The chemical substance elemental mercury (CAS. No. 7439-97-6) is subject...

RARE EARTH ELEMENTS: A REVIEW OF PRODUCTION, PROCESSING, RECYCLING, AND ASSOCIATED ENVIRONMENTAL ISSUES

EPA Science Inventory

Rare earth elements (REEs) are a group of 15 chemical elements in the periodic table, specifically the lanthanides. Two other elements, scandium and yttrium, have a similar physiochemistry to the lanthanides, are commonly found in the same mineral assemblages, and are often refe...

A Short History of Three Chemical Shifts

ERIC Educational Resources Information Center

Nagaoka, Shin-ichi

2007-01-01

A short history of chemical shifts in nuclear magnetic resonance (NMR), electron spectroscopy for chemical analysis (ESCA) and Mossbauer spectroscopy, which are useful for chemical studies, is described. The term chemical shift is shown to have originated in the mistaken assumption that nuclei of a given element would all undergo resonance at the…

Evidence of Coal-Fly-Ash Toxic Chemical Geoengineering in the Troposphere: Consequences for Public Health

PubMed Central

Herndon, J. Marvin

2015-01-01

The widespread, intentional and increasingly frequent chemical emplacement in the troposphere has gone unidentified and unremarked in the scientific literature for years. The author presents evidence that toxic coal combustion fly ash is the most likely aerosolized particulate sprayed by tanker-jets for geoengineering, weather-modification and climate-modification purposes and describes some of the multifold consequences on public health. Two methods are employed: (1) Comparison of 8 elements analyzed in rainwater, leached from aerosolized particulates, with corresponding elements leached into water from coal fly ash in published laboratory experiments, and (2) Comparison of 14 elements analyzed in dust collected outdoors on a high-efficiency particulate air (HEPA) filter with corresponding elements analyzed in un-leached coal fly ash material. The results show: (1) the assemblage of elements in rainwater and in the corresponding experimental leachate are essentially identical. At a 99% confidence interval, they have identical means (T-test) and identical variances (F-test); and (2) the assemblage of elements in the HEPA dust and in the corresponding average un-leached coal fly ash are likewise essentially identical. The consequences on public health are profound, including exposure to a variety of toxic heavy metals, radioactive elements, and neurologically-implicated chemically mobile aluminum released by body moisture in situ after inhalation or through transdermal induction. PMID:26270671

An alpha particle instrument with alpha, proton, and X-ray modes for planetary chemical analyses

NASA Technical Reports Server (NTRS)

Economou, T. E.; Turkevich, A. L.

1976-01-01

The interaction of alpha particles with matter is employed in a compact instrument that could provide rather complete in-situ chemical analyses of surfaces and thin atmospheres of extraterrestrial bodies. The instrument is a miniaturized and improved version of the Surveyor lunar instrument. The backscattering of alpha particles and (alpha, p) reactions provide analytical data on the light elements (carbon-iron). An X-ray mode that detects the photons produced by the alpha sources provides sensitivity and resolution for the chemical elements heavier than about silicon. The X-rays are detected by semiconductor detectors having a resolution between 150 and 250 eV at 5.9 keV. Such an instrument can identify and determine with good accuracy 99 percent of the atoms (except hydrogen) in rocks. For many trace elements, the detecting sensitivity is a few ppm. Auxiliary sources could be used to enhance the sensitivities for elements of special interest. The instrument could probably withstand the acceleration involved in semi-hard landings.

Chemical evolution of a pleistocene rhyolitic center: Sierra La Primavera, Jalisco, México

NASA Astrophysics Data System (ADS)

Mahood, Gail A.

1981-06-01

The late Pleistocene caldera complex of the Sierra La Primavera, Jalisco, México, contains well-exposed lava flows and domes, ash-flow tuff, air-fall pumice, and caldera-lake sediments. All eruptive units are high-silica rhyolites, but systematic chemical differences correlate with age and eruptive mode. The caldera-producing unit, the 45-km3 Tala Tuff, is zoned from a mildly peralkaline first-erupted portion enriched in Na, Rb, Cs, Cl, F, Zn, Y, Zr, Hf, Ta, Nb, Sb, HREE, Pb, Th, and U to a metaluminous last-erupted part enriched in K, LREE, Sc, and Ti; Al, Ca, Mg, Mn, Fe, and Eu are constant within analytical errors. The earliest post-caldera lava, the south-central dome, is nearly identical to the last-erupted portion of the Tala Tuff, whereas the slightly younger north-central dome is chemically transitional from the south-central dome to later, moremafic, ring domes. This sequence of ash-flow tuff and domes represents the tapping of progressively deeper levels of a zoned magma chamber 95,000 ± 5,000 years ago. Since that time, the lavas that erupted 75,000, 60,000, and 30,000 years ago have become decreasingly peralkaline and progressively enriched only in Si, Rb, Cs, and possibly U. They represent successive eruption of the uppermost magma in the post-95,000-year magma chamber. Eruptive units of La Primavera are either aphyric or contain up to 15% phenocrysts of sodic sanidine ≧quartz >ferrohedenbergite >fayalite>ilmenite±titanomagnetite. Whereas major-element compositions of sanidine, clinopyroxene, and fayalite phenocrysts changed only slightly between eruptive groups, concentrations of many trace elements changed by factors of 5 to 10, resulting in crystal/glass partition coefficients that differ by factors of up to 20 between successively erupted units. The extreme variations in partitioning behavior are attributed to small changes in bulk composition of the melt because major-element compositions of the phenocrysts and temperature, pressure, and oxygen fugacity of the magma all remained essentially constant. Crystal settling and incremental partial melting by themselves appear incapable of producing either the chemical gradients within the Tala Tuff magma chamber or the trends with time in the post-caldera lavas. Transport of trace metals as volatile complexes within the thermal and gravitational gradient in volatilerich but water-undersaturated magma is considered the dominant process responsible for compositional zonation in the Tala Tuff. The evolution of the post-caldera lavas with time is thought to involve the diffusive emigration of trace elements from a relatively dry magma as a decreasing proportion of network modifiers and/or a decreasing concentration of complexing ligands progressively reduced trace-metal-site availability in the silicate melt.

Genetic interpretations of elemental and chemical differences in a soil chronosequence, California

USGS Publications Warehouse

Harden, J.W.

1988-01-01

Soils developed on fluvial terraces in central California have similar parent materials, climatic settings, vegetation cover and slopes but range in age from 40,000 to 3,000,000 years. The soils have chemical compositions that change systematically with increasing age. Such chemical differentiation is most likely the result of long-term weathering and mineralogical transformations that occurred since deposition of terrace fills and stabilization of the geomorphic surfaces. The changes in composition with time closely mimic other studies on mineral weathering, in which alkali and alkali-earth elements are lost more rapidly than transitional elements. The relative rates of element loss were determined by changes in element ratios over time. Net losses and gains of elements in different size fractions were monitored by their concentrations relative to Zr, the most stable constituent. Both sand and finer size fractions have lost considerable amounts of Ca, Mg, Na and K. Aluminum appears to have been lost from the sand fraction and gained in the fine fraction over a 3-million-year-time-span. Although there is no evidence for losses of Fe and Ti from sands, there is a net influx of Fe and Ti into finer fractions, probably gained from undetectable yet significant weathering of sand grains. Etching of sand grains, clay mineralogy, and microprobe analyses also indicate that the soils have undergone these chemical transformations during their formation. Mineralogical analyses also mimic other studies on mineral weathering, in which the pyroxenes weather more rapidly than hornblende, which weathers more rapidly than sphene or zircon. ?? 1988.

Heterogeneity of reward mechanisms.

PubMed

Lajtha, A; Sershen, H

2010-06-01

The finding that many drugs that have abuse potential and other natural stimuli such as food or sexual activity cause similar chemical changes in the brain, an increase in extracellular dopamine (DA) in the shell of the nucleus accumbens (NAccS), indicated some time ago that the reward mechanism is at least very similar for all stimuli and that the mechanism is relatively simple. The presently available information shows that the mechanisms involved are more complex and have multiple elements. Multiple brain regions, multiple receptors, multiple distinct neurons, multiple transmitters, multiple transporters, circuits, peptides, proteins, metabolism of transmitters, and phosphorylation, all participate in reward mechanisms. The system is variable, is changed during development, is sex-dependent, and is influenced by genetic differences. Not all of the elements participate in the reward of all stimuli. Different set of mechanisms are involved in the reward of different drugs of abuse, yet different mechanisms in the reward of natural stimuli such as food or sexual activity; thus there are different systems that distinguish different stimuli. Separate functions of the reward system such as anticipation, evaluation, consummation and identification; all contain function-specific elements. The level of the stimulus also influences the participation of the elements of the reward system, there are possible reactions to even below threshold stimuli, and excessive stimuli can change reward to aversion involving parts of the system. Learning and memory of past reward is an important integral element of reward and addictive behavior. Many of the reward elements are altered by repeated or chronic stimuli, and chronic exposure to one drug is likely to alter the response to another stimulus. To evaluate and identify the reward stimulus thus requires heterogeneity of the reward components in the brain.

Characterization, partitioning, and potential ecological risk quantification of trace elements in coal fly ash.

PubMed

Usmani, Zeba; Kumar, Vipin

2017-06-01

Coal-based thermal power plants are the major source of power generation in India. Combustion of coal gives rise to by-products such as fly ash (FA) in huge quantities. The current study focuses on physico-chemical and mineralogical characterization and risk evaluation of FA, generated from five thermal power plants (TPPs) of India. The coal, and corresponding FA and bottom ash (BA) were further analyzed for trace elements in order to observe the enrichment and partitioning behavior of elements. The environmental risk assessment of trace elements in FA was performed in accordance with geoaccumulation index (I geo ) and potential ecological risk index (PERI). The results demonstrated that FA was enriched predominantly in SiO 2 , Al 2 O 3 , and Fe 2 O 3 along with small concentrations of CaO and MgO. The mineral phases identified in FA were quartz, mullite, hematite, and magnetite. Elemental characterization indicated that the metals were more enriched in FA as compared to coal and BA. The concentrations of trace elements, Cr, Pb, Hg, and As in FA (TPPs), varied from 12.59-24.28, 22.68-43.19, <0.0001-2.29, and 0.08-3.39 mg/kg, respectively. Maximum enrichment ratio (ER) was observed for Pb (5.21) in TPP3 FA. Hg in TPP1 showed the highest partition ratio (PR) value. I geo values for metals were mostly below zero. The PERI values indicated moderate risk from TPP4 FA and low risk from TPP1, TPP2, TPP3, and TPP5 FA to the environment, according to the threshold values provided.

Element specificity of ortho-positronium annihilation for alkali-metal loaded SiO2 glasses.

PubMed

Sato, K; Hatta, T

2015-03-07

Momentum distributions associated with ortho-positronium (o-Ps) pick-off annihilation photon are often influenced by light elements, as, e.g., carbon, oxygen, and fluorine. This phenomenon, so-called element specificity of o-Ps pick-off annihilation, has been utilized for studying the elemental environment around the open spaces. To gain an insight into the element specificity of o-Ps pick-off annihilation, the chemical shift of oxygen 1s binding energy and the momentum distributions associated with o-Ps pick-off annihilation were systematically investigated for alkali-metal loaded SiO2 glasses by means of X-ray photoelectron spectroscopy and positron-age-momentum correlation spectroscopy, respectively. Alkali metals introduced into the open spaces surrounded by oxygen atoms cause charge transfer from alkali metals to oxygen atoms, leading to the lower chemical shift for the oxygen 1s binding energy. The momentum distribution of o-Ps localized into the open spaces is found to be closely correlated with the oxygen 1s chemical shift. This correlation with the deepest 1s energy level evidences that the element specificity of o-Ps originates from pick-off annihilation with orbital electrons, i.e., dominantly with oxygen 2p valence electrons and s electrons with lower probability.

Chemistry Division. Quarterly progress report for period ending June 30, 1949

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1949-09-14

Progress reports are presented for the following tasks: (1) nuclear and chemical properties of heavy elements (solution chemistry, phase rule studies); (2) nuclear and chemical properties of elements in the fission product region; (3) general nuclear chemistry; (4) radio-organic chemistry; (5) chemistry of separations processes; (6) physical chemistry and chemical physics; (7) radiation chemistry; (8) physical measurements and instrumentation; and (9) analytical chemistry. The program of the chemistry division is divided into two efforts of approximately equal weight with respect to number of personnel, chemical research, and analytical service for the Laboratory. The various research problems fall into the followingmore » classifications: (1) chemical separation processes for isolation and recovery of fissionable material, production of radioisotopes, and military applications; (2) reactor development; and (3) fundamental research.« less

Recent advances of lanthanum-based perovskite oxides for catalysis

DOE PAGES

Zhu, Huiyuan; Zhang, Pengfei; Dai, Sheng

2015-09-21

There is a need to reduce the use of noble metal elements especially in the field of catalysis, where noble metals are ubiquitously applied. To this end, perovskite oxides, an important class of mixed oxide, have been attracting increasing attention for decades as potential replacements. Benefiting from the extraordinary tunability of their compositions and structures, perovskite oxides can be rationally tailored and equipped with targeted physical and chemical properties e.g. redox behavior, oxygen mobility, and ion conductivity for enhanced catalysis. Recently, the development of highly efficient perovskite oxide catalysts has been extensively studied. This review article summarizes the recent developmentmore » of lanthanum-based perovskite oxides as advanced catalysts for both energy conversion applications and traditional heterogeneous reactions.« less

Processing and property evaluation of tungsten-based mixed oxides for photovoltaics and optoelectronics

NASA Astrophysics Data System (ADS)

Vargas, Mirella

Tungsten Oxide (WO3) films and low-dimensional structures have proven to be promising candidates in the fields of photonics and electronics. WO3 is a well-established n-type semiconductor characterized by unique electrochromic behavior, an ideal optical band gap that permits transparency over a wide spectral range, and high chemical integrity. The plethora of diverse properties endow WO3 to be highly effective in applications related to electrochromism, gas sensing, and deriving economical energy. Compared to the bulk films, a materials system involving WO3 and a related species (elements or metal oxides) offer the opportunity to tailor the electrochromic response, and an overall enhancement of the physio-chemical and optical properties. In the present case, WO3 and TiO2 composite films have been fabricated by reactive magnetron sputtering employing W/Ti alloy targets, and individual W and Ti targets for co-sputtering. Composite WO3-TiO2 films were fabricated with variable chemical composition and the effect of variable bulk chemistry on film structure, surface/interface chemistry and chemical valence state of the W and Ti cations was investigated in detail. The process-property relationships between composition and physical properties for the films deposited by using W/Ti alloy targets of variable Ti content are associated with decreases in the deposition rate of the WO3-TiO2 films due to the lower sputter yield of the strongly bonded TiO2 formed on the target surface. Additionally, for the co-sputtered films using variable tungsten power, the optical properties demonstrate unique optical modulation. The changes associated with the physical color of the films demonstrate the potential to tailor the optical behavior for the design and fabrication of multilayer photovoltaic and catalytic devices. The process-structure-property correlation derived in this work will provide a road-map to optimize and produce W-Ti-O thin films with desired properties for a given technological application.

Chemical Differentiation of Osseous, Dental, and Non-skeletal Materials in Forensic Anthropology using Elemental Analysis.

PubMed

Zimmerman, Heather A; Meizel-Lambert, Cayli J; Schultz, John J; Sigman, Michael E

2015-03-01

Forensic anthropologists are generally able to identify skeletal materials (bone and tooth) using gross anatomical features; however, highly fragmented or taphonomically altered materials may be problematic to identify. Several chemical analysis techniques have been shown to be reliable laboratory methods that can be used to determine if questionable fragments are osseous, dental, or non-skeletal in nature. The purpose of this review is to provide a detailed background of chemical analysis techniques focusing on elemental compositions that have been assessed for use in differentiating osseous, dental, and non-skeletal materials. More recently, chemical analysis studies have also focused on using the elemental composition of osseous/dental materials to evaluate species and provide individual discrimination, but have generally been successful only in small, closed groups, limiting their use forensically. Despite significant advances incorporating a variety of instruments, including handheld devices, further research is necessary to address issues in standardization, error rates, and sample size/diversity. Copyright © 2014 Forensic Science Society. Published by Elsevier Ireland Ltd. All rights reserved.

Molecular manipulations for enhancing luminescent bioreporters performance in the detection of toxic chemicals.

PubMed

Yagur-Kroll, Sharon; Belkin, Shimshon

2014-01-01

Microbial whole-cell bioreporters are genetically modified microorganisms that produce a quantifiable output in response to the presence of toxic chemicals or other stress factors. These bioreporters harbor a genetic fusion between a sensing element (usually a gene regulatory element responsive to the target) and a reporter element, the product of which may be quantitatively monitored either by its presence or by its activity. In this chapter we review genetic manipulations undertaken in order to improve bioluminescent bioreporter performance by increasing luminescent output, lowering the limit of detection, and shortening the response time. We describe molecular manipulations applied to all aspects of whole-cell bioreporters: the host strain, the expression system, the sensing element, and the reporter element. The molecular construction of whole-cell luminescent bioreporters, harboring fusions of gene promoter elements to reporter genes, has been around for over three decades; in most cases, these two genetic elements are combined "as is." This chapter outlines diverse molecular manipulations for enhancing the performance of such sensors.

Strategies for the engineered phytoremediation of toxic element pollution: mercury and arsenic.

PubMed

Meagher, Richard B; Heaton, Andrew C P

2005-12-01

Plants have many natural properties that make them ideally suited to clean up polluted soil, water, and air, in a process called phytoremediation. We are in the early stages of testing genetic engineering-based phytoremediation strategies for elemental pollutants like mercury and arsenic using the model plant Arabidopsis. The long-term goal is to develop and test vigorous, field-adapted plant species that can prevent elemental pollutants from entering the food-chain by extracting them to aboveground tissues, where they can be managed. To achieve this goal for arsenic and mercury, and pave the way for the remediation of other challenging elemental pollutants like lead or radionucleides, research and development on native hyperaccumulators and engineered model plants needs to proceed in at least eight focus areas: (1) Plant tolerance to toxic elementals is essential if plant roots are to penetrate and extract pollutants efficiently from heterogeneous contaminated soils. Only the roots of mercury- and arsenic-tolerant plants efficiently contact substrates heavily contaminated with these elements. (2) Plants alter their rhizosphere by secreting various enzymes and small molecules, and by adjusting pH in order to enhance extraction of both essential nutrients and toxic elements. Acidification favors greater mobility and uptake of mercury and arsenic. (3) Short distance transport systems for nutrients in roots and root hairs requires numerous endogenous transporters. It is likely that root plasma membrane transporters for iron, copper, zinc, and phosphate take up ionic mercuric ions and arsenate. (4) The electrochemical state and chemical speciation of elemental pollutants can enhance their mobility from roots up to shoots. Initial data suggest that elemental and ionic mercury and the oxyanion arsenate will be the most mobile species of these two toxic elements. (5) The long-distance transport of nutrients requires efficient xylem loading in roots, movement through the xylem up to leaves, and efficient xylem unloading aboveground. These systems can be enhanced for the movement of arsenic and mercury. (6) Aboveground control over the electrochemical state and chemical speciation of elemental pollutants will maximize their storage in leaves, stems, and vascular tissues. Our research suggests ionic Hg(II) and arsenite will be the best chemical species to trap aboveground. (7) Chemical sinks can increase the storage capacity for essential nutrients like iron, zinc, copper, sulfate, and phosphate. Organic acids and thiol-rich chelators are among the important chemical sinks that could trap maximal levels of mercury and arsenic aboveground. (8) Physical sinks such as subcellular vacuoles, epidermal trichome cells, and dead vascular elements have shown the evolutionary capacity to store large quantities of a few toxic pollutants aboveground in various native hyperaccumulators. Specific plant transporters may already recognize gluthione conjugates of Hg(II) or arsenite and pump them into vacuole.

Studies of the Variables Affecting Behavior of Larval Zebrafish for Developmental Neurotoxicity Testing

EPA Science Inventory

The U.S. Environmental Protection Agency is evaluating methods to screen and prioritize large numbers of chemicals for developmental toxicity. We are exploring methods to detect developmentally neurotoxic chemicals using zebrafish behavior at 6 days of age. The behavioral paradig...

NETL’s Rare Earth Elements Research

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

The National Energy Technology Laboratory has established a Rare Earth Elements (REE) program. REEs are a series of 17 chemical elements found in the Earth’s crust. They are an essential component to technology, health care, transportation and national defense.

Re-187-Os-187, Pt-190-Os-186 Isotopic and Highly Siderophile Element Systematics of Group IVA Irons

NASA Technical Reports Server (NTRS)

Walker, R. J.; McCoy, T. J.; Schulte, R. F.; McDonough, W. F.; Ash, R. D.

2005-01-01

We have recently completed Re-187-Os-187 and Pt-190-Os-186 isotopic and elemental studies of the two largest magmatic iron meteorite groups, IIAB and IIIAB [1]. These studies revealed closed-system behavior of both isotopic systems, but complex trace element behavior for Re, Pt and Os in group IIIAB. Here we examine isotopic and trace elemental systematics of group IVA irons. The IVA irons are not as extensively fractionated as IIAB and IIIAB and their apparently less complex crystallization history may make for more robust interpretation of the relative partitioning behavior of Re, Pt and Os, as well as the other highly siderophile elements (HSE) measured here; Pd, Ru and Ir [e.g. 2]. An additional goal of our continuing research plan for iron meteorites is to assess the possibility of relating certain ungrouped irons with major groups via trace element modeling. Here, the isotopic and trace element systematics of the ungrouped irons Nedagolla and EET 83230 are compared with the IVA irons.

Two-Dimensional Nonlinear Finite Element Analysis of CMC Microstructures

NASA Technical Reports Server (NTRS)

Mital, Subodh K.; Goldberg, Robert K.; Bonacuse, Peter J.

2012-01-01

A research program has been developed to quantify the effects of the microstructure of a woven ceramic matrix composite and its variability on the effective properties and response of the material. In order to characterize and quantify the variations in the microstructure of a five harness satin weave, chemical vapor infiltrated (CVI) SiC/SiC composite material, specimens were serially sectioned and polished to capture images that detailed the fiber tows, matrix, and porosity. Open source quantitative image analysis tools were then used to isolate the constituents, from which two dimensional finite element models were generated which approximated the actual specimen section geometry. A simplified elastic-plastic model, wherein all stress above yield is redistributed to lower stress regions, is used to approximate the progressive damage behavior for each of the composite constituents. Finite element analyses under in-plane tensile loading were performed to examine how the variability in the local microstructure affected the macroscopic stress-strain response of the material as well as the local initiation and progression of damage. The macroscopic stress-strain response appeared to be minimally affected by the variation in local microstructure, but the locations where damage initiated and propagated appeared to be linked to specific aspects of the local microstructure.

Electrochemical reduction of (U-40Pu-5Np)O 2 in molten LiCl electrolyte

NASA Astrophysics Data System (ADS)

Iizuka, Masatoshi; Sakamura, Yoshiharu; Inoue, Tadashi

2006-12-01

The electrochemical reduction of neptunium-containing MOX ((U-40Pu-5Np)O 2) was performed in molten lithium chloride melt at 923 K to investigate fundamental behavior of the transuranium elements and applicability of the method to reduction process for these materials. The Np-MOX was electrochemically reduced at the potential lower than -0.6 V vs. Bi-35 mol% Li reference electrode. The reduced metal grains in the surface region of the sample cohered with each other and made the layer of relatively high density, although it did not prevent the reduction of the sample toward the center. Complete reduction of the Np-MOX was shown by the weight change measurement through the electrochemical reduction and also by SEM-EDX observation. The chemical composition of the reduction products was homogeneous and agreed to that of the initial Np-MOX, which indicates that the reduction was completed and not selective among the actinides. The concentrations of the actinide elements, especially plutonium and americium in the electrolyte, increased with the progress of the tests, although their absolute values were very small. It is quite likely that plutonium and americium dissolve into the melt in the same manner as the lanthanide elements in the lithium reduction process.

Classifying organic materials by oxygen-to-carbon elemental ratio to predict the activation regime of cloud condensation nuclei (CCN)

NASA Astrophysics Data System (ADS)

Kuwata, M.; Shao, W.; Lebouteiller, R.; Martin, S. T.

2012-12-01

The governing highly soluble, slightly soluble, or insoluble activation regime of organic compounds as cloud condensation nuclei (CCN) was examined as a function of oxygen-to-carbon elemental ratio (O : C). New data were collected for adipic, pimelic, suberic, azelaic and pinonic acids. Secondary organic materials (SOMs) produced by α-pinene ozonolysis and isoprene photo-oxidation were also included in the analysis. The saturation concentrations C of the organic compounds in aqueous solutions served as the key parameter for delineating regimes of CCN activation, and the values of C were tightly correlated to the O : C ratios. The highly soluble, slightly soluble, and insoluble regimes of CCN activation were found to correspond to ranges of [O : C] > 0.6, 0.2 < [O : C] < 0.6, and [O : C] < 0.2, respectively. These classifications were evaluated against CCN activation data of isoprene-derived SOM (O : C = 0.69-0.72) and α-pinene-derived SOM (O : C = 0.38-0.48). Isoprene-derived SOM had highly soluble activation behavior, consistent with its high O : C ratio. For α-pinene-derived SOM, although CCN activation can be modeled as a highly soluble mechanism, this behavior was not predicted by the O : C ratio, for which a slightly soluble mechanism was anticipated. Complexity in chemical composition, resulting in continuous water uptake and the absence of a deliquescence transition that can thermodynamically limit CCN activation, might explain the differences of α-pinene-derived SOM compared to the behavior of pure organic compounds. The present results suggest that atmospheric particles dominated by hydrocarbon-like organic components do not activate (i.e. insoluble regime) whereas those dominated by oxygenated organic components activate (i.e. highly soluble regime).

Classifying organic materials by oxygen-to-carbon elemental ratio to predict the activation regime of Cloud Condensation Nuclei (CCN)

NASA Astrophysics Data System (ADS)

Kuwata, M.; Shao, W.; Lebouteiller, R.; Martin, S. T.

2013-05-01

The governing highly soluble, slightly soluble, or insoluble activation regime of organic compounds as cloud condensation nuclei (CCN) was examined as a function of oxygen-to-carbon elemental ratio (O : C). New data were collected for adipic, pimelic, suberic, azelaic, and pinonic acids. Secondary organic materials (SOMs) produced by α-pinene ozonolysis and isoprene photo-oxidation were also included in the analysis. The saturation concentrations C of the organic compounds in aqueous solutions served as the key parameter for delineating regimes of CCN activation, and the values of C were tightly correlated to the O : C ratios. The highly soluble, slightly soluble, and insoluble regimes of CCN activation were found to correspond to ranges of [O : C] > 0.6, 0.2 < [O : C] < 0.6, and [O : C] < 0.2, respectively. These classifications were evaluated against CCN activation data of isoprene-derived SOM (O : C = 0.69-0.72) and α-pinene-derived SOM (O : C = 0.38-0.48). Isoprene-derived SOM had highly soluble activation behavior, consistent with its high O : C ratio. For α-pinene-derived SOM, although CCN activation can be modeled as a highly soluble mechanism, this behavior was not predicted by the O : C ratio, for which a slightly soluble mechanism was anticipated. Complexity in chemical composition, resulting in continuous water uptake and the absence of a deliquescence transition that can thermodynamically limit CCN activation, might explain the difference in the behavior of α-pinene-derived SOM compared to that of pure organic compounds. The present results suggest that atmospheric particles dominated by hydrocarbon-like organic components do not activate (i.e., insoluble regime) whereas those dominated by oxygenated organic components activate (i.e., highly soluble regime) for typical atmospheric cloud life cycles.

Potential impact of acid precipitation on arsenic and selenium.

PubMed Central

Mushak, P

1985-01-01

The potential impact of acidic precipitation on the environmental mobility of the metalloids arsenic (As) and selenium (Se) has not been given much attention and is poorly understood. As with other elements, the interest here is the potential effect of environmental acidification on environmental behavior in ways that are relevant to human exposure to these metalloids. Available information on acid precipitation and the environmental behavior of these metalloids do, however, permit some preliminary conclusions to be drawn. Both As and Se appear to be mobilized from household plumbing into tap water by the corrosive action of soft, mildly acidic water, while surface water catchment systems in areas impacted by acidic deposition may contain elevated soluble As levels. Acidification of aquatic ecosystems that are drinking water sources may pose the prospect of enhanced release of As from sediment to water as well as reduction in water levels of Se. Acidification of ground waters, where As appears to be especially mobile, is of particular concern in this regard. The potential impact of acidic deposition on As and Se in soils cannot readily be assessed with respect to human exposure, but it would appear that the behavior of these metalloids in poorly buffered, poorly immobilizing soils, e.g., sandy soils of low metal hydrous oxide content, would be most affected. The effect is opposite for the two elements; lowered pH would appear to enhance As mobility and to reduce Se availability. Altered acidity of both soil and aquatic systems poses a risk for altered biotransformation processes involving both As and Se, thereby affecting the relative amounts of different chemical forms varying in their toxicity to humans as well as influencing biogeochemical cycling. PMID:4076075

Potential impact of acid precipitation on arsenic and selenium.

PubMed

Mushak, P

1985-11-01

The potential impact of acidic precipitation on the environmental mobility of the metalloids arsenic (As) and selenium (Se) has not been given much attention and is poorly understood. As with other elements, the interest here is the potential effect of environmental acidification on environmental behavior in ways that are relevant to human exposure to these metalloids. Available information on acid precipitation and the environmental behavior of these metalloids do, however, permit some preliminary conclusions to be drawn. Both As and Se appear to be mobilized from household plumbing into tap water by the corrosive action of soft, mildly acidic water, while surface water catchment systems in areas impacted by acidic deposition may contain elevated soluble As levels. Acidification of aquatic ecosystems that are drinking water sources may pose the prospect of enhanced release of As from sediment to water as well as reduction in water levels of Se. Acidification of ground waters, where As appears to be especially mobile, is of particular concern in this regard. The potential impact of acidic deposition on As and Se in soils cannot readily be assessed with respect to human exposure, but it would appear that the behavior of these metalloids in poorly buffered, poorly immobilizing soils, e.g., sandy soils of low metal hydrous oxide content, would be most affected. The effect is opposite for the two elements; lowered pH would appear to enhance As mobility and to reduce Se availability. Altered acidity of both soil and aquatic systems poses a risk for altered biotransformation processes involving both As and Se, thereby affecting the relative amounts of different chemical forms varying in their toxicity to humans as well as influencing biogeochemical cycling.

Atomic Structure and Valence: Level II, Unit 10, Lesson 1; Chemical Bonding: Lesson 2; The Table of Elements: Lesson 3; Electrolysis: Lesson 4. Advanced General Education Program. A High School Self-Study Program.

ERIC Educational Resources Information Center

Manpower Administration (DOL), Washington, DC. Job Corps.

This self-study program for high-school level contains lessons on: Atomic Structure and Valence, Chemical Bonding, The Table of Elements, and Electrolysis. Each of the lessons concludes with a Mastery Test to be completed by the student. (DB)

Understanding the Idea of Chemical Elements and Their Periodic Classification in Spanish Students Aged 16-18 Years

ERIC Educational Resources Information Center

Franco-Mariscal, Antonio-Joaquín; Oliva-Martínez, José María; Almoraima Gil, M. L.

2016-01-01

The work reported here involved a comparative study regarding the understanding that high school students (16-18 years) have of the concept of chemical elements and their periodic classification. More specifically, the level of knowledge on this topic was compared before and after the completion of baccalaureate studies in a sample of Spanish…

A Game-Based Approach to Learning the Idea of Chemical Elements and Their Periodic Classification

ERIC Educational Resources Information Center

Franco-Mariscal, Antonio Joaquín; Oliva-Martínez, José María; Blanco-López, Ángel; España-Ramos, Enrique

2016-01-01

In this paper, the characteristics and results of a teaching unit based on the use of educational games to learn the idea of chemical elements and their periodic classification in secondary education are analyzed. The method is aimed at Spanish students aged 15-16 and consists of 24 1-h sessions. The results obtained on implementing the teaching…

How people think about the chemicals in cigarette smoke: a systematic review.

PubMed

Morgan, Jennifer C; Byron, M Justin; Baig, Sabeeh A; Stepanov, Irina; Brewer, Noel T

2017-08-01

Laws and treaties compel countries to inform the public about harmful chemicals (constituents) in cigarette smoke. To encourage relevant research by behavioral scientists, we provide a primer on cigarette smoke toxicology and summarize research on how the public thinks about cigarette smoke chemicals. We systematically searched PubMed in July 2016 and reviewed citations from included articles. Four central findings emerged across 46 articles that met inclusion criteria. First, people were familiar with very few chemicals in cigarette smoke. Second, people knew little about cigarette additives, assumed harmful chemicals are added during manufacturing, and perceived cigarettes without additives to be less harmful. Third, people wanted more information about constituents. Finally, well-presented chemical information increased knowledge and awareness and may change behavior. This research area is in urgent need of behavioral science. Future research should investigate whether educating the public about these chemicals increases risk perceptions and quitting.

Finite Element Simulation of Articular Contact Mechanics with Quadratic Tetrahedral Elements

PubMed Central

Maas, Steve A.; Ellis, Benjamin J.; Rawlins, David S.; Weiss, Jeffrey A.

2016-01-01

Although it is easier to generate finite element discretizations with tetrahedral elements, trilinear hexahedral (HEX8) elements are more often used in simulations of articular contact mechanics. This is due to numerical shortcomings of linear tetrahedral (TET4) elements, limited availability of quadratic tetrahedron elements in combination with effective contact algorithms, and the perceived increased computational expense of quadratic finite elements. In this study we implemented both ten-node (TET10) and fifteen-node (TET15) quadratic tetrahedral elements in FEBio (www.febio.org) and compared their accuracy, robustness in terms of convergence behavior and computational cost for simulations relevant to articular contact mechanics. Suitable volume integration and surface integration rules were determined by comparing the results of several benchmark contact problems. The results demonstrated that the surface integration rule used to evaluate the contact integrals for quadratic elements affected both convergence behavior and accuracy of predicted stresses. The computational expense and robustness of both quadratic tetrahedral formulations compared favorably to the HEX8 models. Of note, the TET15 element demonstrated superior convergence behavior and lower computational cost than both the TET10 and HEX8 elements for meshes with similar numbers of degrees of freedom in the contact problems that we examined. Finally, the excellent accuracy and relative efficiency of these quadratic tetrahedral elements was illustrated by comparing their predictions with those for a HEX8 mesh for simulation of articular contact in a fully validated model of the hip. These results demonstrate that TET10 and TET15 elements provide viable alternatives to HEX8 elements for simulation of articular contact mechanics. PMID:26900037

The partitioning behavior of trace element and its distribution in the surrounding soil of a cement plant integrated utilization of hazardous wastes.

PubMed

Yang, Zhenzhou; Chen, Yan; Sun, Yongqi; Liu, Lili; Zhang, Zuotai; Ge, Xinlei

2016-07-01

In the present study, the trace elements partitioning behavior during cement manufacture process were systemically investigated as well as their distribution behaviors in the soil surrounding a cement plant using hazardous waste as raw materials. In addition to the experimental analysis, the thermodynamic equilibrium calculations were simultaneously conducted. The results demonstrate that in the industrial-scale cement manufacture process, the trace elements can be classified into three groups according to their releasing behaviors. Hg is recognized as a highly volatile element, which almost totally partitions into the vapor phase. Co, Cu, Mn, V, and Cr are considered to be non-volatile elements, which are largely incorporated into the clinker. Meanwhile, Cd, Ba, As, Ni, Pb, and Zn can be classified into semi-volatile elements, as they are trapped into clinker to various degrees. Furthermore, the trace elements emitted into the flue gas can be adsorbed onto the fine particles, transport and deposit in the soil, and it is clarified here that the soil around the cement plant is moderately polluted by Cd, slightly polluted by As, Cr, Ba, Zn, yet rarely influenced by Co, Mn, Ni, Cu, Hg, and V elements. It was also estimated that the addition of wastes can efficiently reduce the consumption of raw materials and energy. The deciphered results can thus provide important insights for estimating the environmental impacts of the cement plant on its surroundings by utilizing wastes as raw materials.

Elastic and Mechanical Properties of the MAX Phases

NASA Astrophysics Data System (ADS)

Barsoum, Michel W.; Radovic, Miladin

2011-08-01

The more than 60 ternary carbides and nitrides, with the general formula Mn+1AXn—where n = 1, 2, or 3; M is an early transition metal; A is an A-group element (a subset of groups 13-16); and X is C and/or N—represent a new class of layered solids, where Mn+1Xn layers are interleaved with pure A-group element layers. The growing interest in the Mn+1AXn phases lies in their unusual, and sometimes unique, set of properties that can be traced back to their layered nature and the fact that basal dislocations multiply and are mobile at room temperature. Because of their chemical and structural similarities, the MAX phases and their corresponding MX phases share many physical and chemical properties. In this paper we review our current understanding of the elastic and mechanical properties of bulk MAX phases where they differ significantly from their MX counterparts. Elastically the MAX phases are in general quite stiff and elastically isotropic. The MAX phases are relatively soft (2-8 GPa), are most readily machinable, and are damage tolerant. Some of them are also lightweight and resistant to thermal shock, oxidation, fatigue, and creep. In addition, they behave as nonlinear elastic solids, dissipating 25% of the mechanical energy during compressive cycling loading of up to 1 GPa at room temperature. At higher temperatures, they undergo a brittle-to-plastic transition, and their mechanical behavior is a strong function of deformation rate.

Mechanical properties and leaching modeling of activated incinerator bottom ash in Portland cement blends

DOE Office of Scientific and Technical Information (OSTI.GOV)

Onori, Roberta, E-mail: Roberta.onori@uniroma1.it; Polettini, Alessandra; Pomi, Raffaella

2011-02-15

In the present study the evolution of mechanical strength and the leaching behavior of major and trace elements from activated incinerator bottom ash/Portland cement mixtures were investigated. Chemical and mechanical activation were applied with the purpose of improving the reactivity of bottom ash in cement blends. Chemical activation made use of NaOH, KOH, CaCl{sub 2} or CaSO{sub 4}, which were selected for the experimental campaign on the basis of the results from previous studies. The results indicated that CaCl{sub 2} exhibited by far the best effects on the evolution of the hydration process in the mixtures; a positive effect onmore » mechanical strength was also observed when CaSO{sub 4} was used as the activator, while the gain in strength produced by KOH and NaOH was irrelevant. Geochemical modeling of the leaching solutions provided information on the mineral phases responsible for the release of major elements from the hardened materials and also indicated the important role played by surface sorption onto amorphous Fe and Al minerals in dictating the leaching of Pb. The leaching of the other trace metal cations investigated (Cu, Ni and Zn) could not be explained by any pure mineral included in the thermodynamic database used, suggesting they were present in the materials in the form of complex minerals or phase assemblages for which no consistent thermodynamic data are presently available in the literature.« less

Development, characterization and dissolution behavior of calcium-aluminoborate glass wasteforms to immobilize rare-earth oxides.

PubMed

Kim, Miae; Corkhill, Claire L; Hyatt, Neil C; Heo, Jong

2018-03-28

Calcium-aluminoborate (CAB) glasses were developed to sequester new waste compositions made of several rare-earth oxides generated from the pyrochemical reprocessing of spent nuclear fuel. Several important wasteform properties such as waste loading, processability and chemical durability were evaluated. The maximum waste loading of the CAB compositions was determined to be ~56.8 wt%. Viscosity and the electrical conductivity of the CAB melt at 1300 °C were 7.817 Pa·s and 0.4603 S/cm, respectively, which satisfies the conditions for commercial cold-crucible induction melting (CCIM) process. Addition of rare-earth oxides to CAB glasses resulted in dramatic decreases in the elemental releases of B and Ca in aqueous dissolution experiments. Normalized elemental releases from product consistency standard chemical durability test were <3.62·10 -5  g·m -2 for Nd, 0.009 g·m -2 for Al, 0.067 g·m -2 for B and 0.073 g·m -2 for Ca (at 90, after 7 days, for SA/V = 2000m -1 ); all meet European and US regulation limits. After 20 d of dissolution, a hydrated alteration layer of ~ 200-nm-thick, Ca-depleted and Nd-rich, was formed at the surface of CAB glasses with 20 mol% Nd 2 O 3 whereas boehmite [AlO(OH)] secondary crystalline phases were formed in pure CAB glass that contained no Nd 2 O 3 .

Mechanical properties and leaching modeling of activated incinerator bottom ash in Portland cement blends.

PubMed

Onori, Roberta; Polettini, Alessandra; Pomi, Raffaella

2011-02-01

In the present study the evolution of mechanical strength and the leaching behavior of major and trace elements from activated incinerator bottom ash/Portland cement mixtures were investigated. Chemical and mechanical activation were applied with the purpose of improving the reactivity of bottom ash in cement blends. Chemical activation made use of NaOH, KOH, CaCl(2) or CaSO(4), which were selected for the experimental campaign on the basis of the results from previous studies. The results indicated that CaCl(2) exhibited by far the best effects on the evolution of the hydration process in the mixtures; a positive effect on mechanical strength was also observed when CaSO(4) was used as the activator, while the gain in strength produced by KOH and NaOH was irrelevant. Geochemical modeling of the leaching solutions provided information on the mineral phases responsible for the release of major elements from the hardened materials and also indicated the important role played by surface sorption onto amorphous Fe and Al minerals in dictating the leaching of Pb. The leaching of the other trace metal cations investigated (Cu, Ni and Zn) could not be explained by any pure mineral included in the thermodynamic database used, suggesting they were present in the materials in the form of complex minerals or phase assemblages for which no consistent thermodynamic data are presently available in the literature. Copyright © 2010 Elsevier Ltd. All rights reserved.

Studies of the Variables Affecting Behavior of Larval Zebrafish for Developmental Neurotoxicity Testing*

EPA Science Inventory

The U.S. Environmental Protection Agency is evaluating methods to screen and prioritize large numbers of chemicals for developmental toxicity. We are exploring methods to screen for developmentally neurotoxic chemicals using zebrafish behavior at 6 days of age. The behavioral par...

Influence of muscle-tendon complex geometrical parameters on modeling passive stretch behavior with the Discrete Element Method.

PubMed

Roux, A; Laporte, S; Lecompte, J; Gras, L-L; Iordanoff, I

2016-01-25

The muscle-tendon complex (MTC) is a multi-scale, anisotropic, non-homogeneous structure. It is composed of fascicles, gathered together in a conjunctive aponeurosis. Fibers are oriented into the MTC with a pennation angle. Many MTC models use the Finite Element Method (FEM) to simulate the behavior of the MTC as a hyper-viscoelastic material. The Discrete Element Method (DEM) could be adapted to model fibrous materials, such as the MTC. DEM could capture the complex behavior of a material with a simple discretization scheme and help in understanding the influence of the orientation of fibers on the MTC׳s behavior. The aims of this study were to model the MTC in DEM at the macroscopic scale and to obtain the force/displacement curve during a non-destructive passive tensile test. Another aim was to highlight the influence of the geometrical parameters of the MTC on the global mechanical behavior. A geometrical construction of the MTC was done using discrete element linked by springs. Young׳s modulus values of the MTC׳s components were retrieved from the literature to model the microscopic stiffness of each spring. Alignment and re-orientation of all of the muscle׳s fibers with the tensile axis were observed numerically. The hyper-elastic behavior of the MTC was pointed out. The structure׳s effects, added to the geometrical parameters, highlight the MTC׳s mechanical behavior. It is also highlighted by the heterogeneity of the strain of the MTC׳s components. DEM seems to be a promising method to model the hyper-elastic macroscopic behavior of the MTC with simple elastic microscopic elements. Copyright © 2015 Elsevier Ltd. All rights reserved.

APOGEE Chemical Abundances of the Sagittarius Dwarf Galaxy System

NASA Astrophysics Data System (ADS)

Hasselquist, Sten; Shetrone, Matthew D.; Smith, Verne V.; Holtzman, Jon A.; McWilliam, Andrew; APOGEE Team

2018-06-01

The Apache Point Observatory Galactic Evolution Experiment provides the opportunity of measuring elemental abundances for C, N, O, Na, Mg, Al, Si, P, K, Ca, V, Cr, Mn, Fe, Co, and Ni in vast numbers of stars. We analyze the chemical-abundance patterns of these elements for 158 red giant stars belonging to the Sagittarius dwarf galaxy (Sgr). This is the largest sample of Sgr stars with detailed chemical abundances, and it is the first time that C, N, P, K, V, Cr, Co, and Ni have been studied at high resolution in this galaxy. We find that the Sgr stars with [Fe/H] > -0.8 are deficient in all elemental abundance ratios (expressed as [X/Fe]) relative to the Milky Way, suggesting that the Sgr stars observed today were formed from gas that was less enriched by Type II SNe than stars formed in the Milky Way. By examining the relative deficiencies of the hydrostatic (O, Na, Mg, and Al) and explosive (Si, P, K, and Mn) elements, our analysis supports the argument that previous generations of Sgr stars were formed with a top-light initial mass function, one lacking the most massive stars that would normally pollute the interstellar medium with the hydrostatic elements. We use a simple chemical-evolution model, flexCE, to further support our claim and conclude that recent stellar generations of Fornax and the Large Magellanic Cloud could also have formed according to a top-light initial mass function. We then exploit the unique chemical abundance patters of the Sgr core to trace stars belonging to the Sgr tidal streams elsewhere in the Milky Way.

Copper-arsenic decoupling in an active geothermal system: A link between pyrite and fluid composition

NASA Astrophysics Data System (ADS)

Tardani, Daniele; Reich, Martin; Deditius, Artur P.; Chryssoulis, Stephen; Sánchez-Alfaro, Pablo; Wrage, Jackie; Roberts, Malcolm P.

2017-05-01

Over the past few decades several studies have reported that pyrite hosts appreciable amounts of trace elements which commonly occur forming complex zoning patterns within a single mineral grain. These chemical zonations in pyrite have been recognized in a variety of hydrothermal ore deposit types (e.g., porphyry Cu-Mo-Au, epithermal Au deposits, iron oxide-copper-gold, Carlin-type and Archean lode Au deposits, among others), showing, in some cases, marked oscillatory alternation of metals and metalloids in pyrite growth zones (e.g., of Cu-rich, As-(Au, Ag)-depleted zones and As-(Au, Ag)-rich, Cu-depleted zones). This decoupled geochemical behavior of Cu and As has been interpreted as a result of chemical changes in ore-forming fluids, although direct evidence connecting fluctuations in hydrothermal fluid composition with metal partitioning into pyrite growth zones is still lacking. In this study, we report a comprehensive trace element database of pyrite from the Tolhuaca Geothermal System (TGS) in southern Chile, a young and active hydrothermal system where fewer pyrite growth rims and mineralization events are present and the reservoir fluid (i.e. ore-forming fluid) is accessible. We combined the high-spatial resolution and X-ray mapping capabilities of electron microprobe analysis (EMPA) with low detection limits and depth-profiling capacity of secondary-ion mass spectrometry (SIMS) in a suite of pyrite samples retrieved from a ∼1 km drill hole that crosses the argillic (20-450 m) and propylitic (650-1000 m) alteration zones of the geothermal system. We show that the concentrations of precious metals (e.g., Au, Ag), metalloids (e.g., As, Sb, Se, Te), and base and heavy metals (e.g., Cu, Co, Ni, Pb) in pyrite at the TGS are significant. Among the elements analyzed, As and Cu are the most abundant with concentrations that vary from sub-ppm levels to a few wt.% (i.e., up to ∼5 wt.% As, ∼1.5 wt.% Cu). Detailed wavelength-dispersive spectrometry (WDS) X-ray maps and SIMS depth vs. isotope concentration profiles reveal that pyrites from the TGS are characterized by chemical zoning where the studied elements occur in different mineralogical forms. Arsenic and Co occur as structurally bound elements in pyrite, Cu and Au in pyrite can occur as both solid solution and submicron-sized particles of chalcopyrite and native Au (or Au tellurides), respectively. Pyrites from the deeper propylitic zone do not show significant zonation and high Cu-(Co)-As concentrations correlate with each other. In contrast, well-developed zonations were detected in pyrite from the shallow argillic alteration zone, where Cu(Co)-rich, As-depleted cores alternate with Cu(Co)-depleted, As-rich rims. These microanalytical data were contrasted with chemical data of fluid inclusions in quartz and calcite veins (high Cu/As ratios) and borehole fluid (low Cu/As ratios) reported at the TGS, showing a clear correspondence between Cu and As concentrations in pyrite-forming fluids and chemical zonation in pyrite. These observations provide direct evidence supporting the selective partitioning of metals into pyrite as a result of changes in ore-forming fluid composition, most likely due to separation of a single-phase fluid into a low-density vapor and a denser brine, capable of fractionating Cu and As.

[Analytical chemistry in works of Maria Skłodowska-Curie].

PubMed

Hulanicki, Adam

2012-01-01

Maria Skłodowska-Curie--a Nobel Prize winner in chemistry--the elements of learning of chemistry gained just by a dint of work of more than ten months in Warsaw in the Institute of Industry and Agriculture Museum. The Nobel Prize concerned a contribution to the progress of chemistry through the discovery of radium and polonium, separation of radium and study of properties of this amazing element. It was awarded for an extremely arduous work, during which the chemical reactions being the principles of analytical chemistry were realized. Unlike to a typical analytical procedure, an initial attempt here was the thousands of kilograms of uranium ore: pitchblende. The final effect was small amounts of new elements: polonium and radium. Both the knowledge and the intuition of the researcher let her have a triumph. The difficulties she experienced because the properties of the searched chemical elements could only be evaluated thanks to the knowledge on other chemical elements. A significant achievement was the determination of the samples by means of radioactivity measurement, which gave rise to radiochemical analytical methods. An extreme analytical precision was demanded in multiple processes of fractional crystallization and precipitation which finally led to the calculation of the atomic mass of radium.

Hydrodynamical instabilities induced by atomic diffusion in F and A stars : Impact on the opacity profile and asteroseimic age determination

NASA Astrophysics Data System (ADS)

Deal, M.; Richard, O.; Vauclair, S.

2017-12-01

Atomic diffusion, including the effect of radiative accelerations on individual elements, leads to important variations of the chemical composition inside the stars. The accumulation in specific layers of the elements, which are the main contributors of the local opacity, leads to hydrodynamical instabilities that modify the internal stellar structure and surface abundances. The modification of the initial chemical composition has important effects on the internal stellar mixing and leads to different surface and internal abundances of the elements. These processes also modify the age determination by asteroseismology.

Direct numerical simulations of a reacting turbulent mixing layer by a pseudospectral-spectral element method

NASA Technical Reports Server (NTRS)

Mcmurtry, Patrick A.; Givi, Peyman

1992-01-01

An account is given of the implementation of the spectral-element technique for simulating a chemically reacting, spatially developing turbulent mixing layer. Attention is given to experimental and numerical studies that have investigated the development, evolution, and mixing characteristics of shear flows. A mathematical formulation is presented of the physical configuration of the spatially developing reacting mixing layer, in conjunction with a detailed representation of the spectral-element method's application to the numerical simulation of mixing layers. Results from 2D and 3D calculations of chemically reacting mixing layers are given.

The factors that have correlation with student behavior to dispose liquid waste

NASA Astrophysics Data System (ADS)

Kusmawaningtyas, Rieneke; Darmajanti, Linda; Soesilo, Tri Edhi Budhi

2017-03-01

Students majoring in chemistry could produce toxic liquid waste in their laboratory practices. They are not allowed to dispose of hazardous laboratory liquid into the environment. The formulation of problem in this study is that not all students have good behavior to dispose liquid waste properly according to their type and chemical properties while it is expected that all students have good behavior to dispose liquid waste with the type and chemical properties in container vessel, even though all students are expected to have behavior to dispose waste in the container vessel with the support of the predisposing factors, enabling factors, and driving factors. The aim of this study is to analyze the type and chemical properties of liquid waste and the relationship between three factors forming behavior with student behavior. The relationship between three factors forming behavior with student behavior was analyzed by correlative analysis. Type and chemical properties known through observation and qualitative analysis. The results of this research is found that enabling factors and driving behavior have a weak relation with student behavior. Nevertheless, predisposing factors has no relation with student behavior. The result of analysis of waste laboratory are known that laboratory liquid waste contains Cu, Fe, and methylene blue which potentially pollute the environment. The findings show that although generally the laboratory use chemicals in small quantities, but the total quantity of laboratory liquid waste produced from all laboratories in some regions must be considered. Moreover, the impact of the big quantity of liquid waste to environment must be taken into account. Thus, it is recommended that students should raise awareness of the risks associated with laboratory liquid waste and, we should provide proper management for a laboratory and policy makers.

Distribution and origin of major and trace elements (particularly REE, U and Th) into labile and residual phases in an acid soil profile (Vosges Mountains, France)

NASA Astrophysics Data System (ADS)

Aubert, D.; Probst, A.; Stille, P.

2003-04-01

Physical and chemical weathering of rocks and minerals lead to soil formation and allow the removal of chemical elements from these systems to ground- or surface waters. But most of the time the determination of element concentrations in soils is not sufficient to estimate whether they are being accumulated or what is their ability to be released in the environment. Thus, the distribution and chemical binding for a given element is very important because it determines its mobility and potential bioavailability throughout a soil profile. Heavy metals and REE (Rare Earth Elements) are particularly of environmental concern because of their potential toxicity. For most of them, their chemical form strongly depends on the evolution of physico-chemical parameters like pH or redox conditions that will induce adsorption-desorption, complexation or co-precipitation phenomena in the material. The purpose of this study is to determine the distribution of several major and trace elements (especially REE, Th and U) in an acidic forested podzolic soil profile from the Vosges Mountains (France). To achieve this goal we use a 7 step sequential extraction procedure that allows determining precisely the origin and the behaviour of particular elements in the environment (Leleyter et al., 1999). In addition we performed leaching experiments using very dilute acetic and hydrochloric acid in order to establish the origin of REE in this soil. The results of the sequential extraction indicate that most of the metals, Th and U are mainly bound to Fe oxides. Organic matter appears also to be a great carrier of P, Ca, Fe and REE even if its content is very low in the deep horizons of the soil. Moreover, we show that in each soil horizon, middle REE (MREE) to heavy REE (HREE) are more labile than light REE (LREE). Leaching experiments using dilute acid solution further suggest that in the shallowest horizons REE largely derive from atmospheric deposition whereas at greater depth, weathering and particularly phosphate mineral weathering (apatite) is the main contributor to labile REE in the soil.

Are C1 chondrites chemically fractionated - A trace element study

NASA Technical Reports Server (NTRS)

Ebihara, M.; Wolf, R.; Anders, E.

1982-01-01

Six C1 chondrite samples and a C2 xenolith from the Plainview H5 chondrite were analyzed by radiochemical neutron activation for a large variety of elements, including rare earths. The sample processing is described, including the irradiation, chemical procedure, rare earths separation, counting techniques, radiochemical purity check, and chemical yields. The results of consistency checks on a number of elements are discussed. Abundances for siderophiles, volatiles, and rare earths are presented and discussed. Tests are presented for fractionation of rare earths and other refractories, compositional uniformity of C1's, and interelement correlations. There is no conclusive evidence for nebular fractionation affecting C1's. Three fractionation-prone rare earths have essentially the same relative abundances in C1's and all other chondrite classes, and hence are apparently not fractionated in C1's.

The Open Cluster Chemical Abundances and Mapping (OCCAM) Survey: Optical Extension for Neutron Capture Elements

NASA Astrophysics Data System (ADS)

Melendez, Matthew; O'Connell, Julia; Frinchaboy, Peter M.; Donor, John; Cunha, Katia M. L.; Shetrone, Matthew D.; Majewski, Steven R.; Zasowski, Gail; Pinsonneault, Marc H.; Roman-Lopes, Alexandre; Stassun, Keivan G.; APOGEE Team

2017-01-01

The Open Cluster Chemical Abundance & Mapping (OCCAM) survey is a systematic survey of Galactic open clusters using data primarily from the SDSS-III/APOGEE-1 survey. However, neutron capture elements are very limited in the IR region covered by APOGEE. In an effort to fully study detailed Galactic chemical evolution, we are conducting a high resolution (R~60,000) spectroscopic abundance analysis of neutron capture elements for OCCAM clusters in the optical regime to complement the APOGEE results. As part of this effort, we present Ba II, La II, Ce II and Eu II results for a few open clusters without previous abundance measurements using data obtained at McDonald Observatory with the 2.1m Otto Struve telescope and Sandiford Echelle Spectrograph.This work is supported by an NSF AAG grant AST-1311835.

Interpretation of trace element and isotope features of basalts: relevance of field relations, petrology, major element data, phase equilibria, and magma chamber modeling in basalt petrogenesis

NASA Astrophysics Data System (ADS)

O'Hara, M. J.; Herzberg, C.

2002-06-01

The concentrations and ratios of the major elements determine the physical properties and the phase equilibria behavior of peridotites and basalts in response to the changing energy contents of the systems. The behavior of the trace elements and isotopic features are influenced in their turn by the phase equilibria, by the physical character of the partial melting and partial crystallization processes, and by the way in which a magma interacts with its wall rocks. Concentrating on the trace element and isotope contents of basalts to the exclusion of the field relations, petrology, major element data, and phase equilibria is as improvident as slaughtering the buffalo for the sake of its tongue. The crust is a cool boundary layer and a density filter, which impedes the upward transfer of hot, dense "primary" picritic and komatiitic liquids. Planetary crusts are sites of large-scale contamination and extensive partial crystallization of primitive melts striving to escape to the surface. Escape of truly unmodified primitive melts to the surface is a rare event, requiring the resolution of daunting problems in chemical and mechanical engineering. Primary status for volumetrically abundant basalts such as mid-ocean ridge basalt, ocean island basalt, and continental flood basalts is denied by their low-pressure cotectic character, first remarked upon on petrological grounds in 1928 and on experimental grounds in 1962. These basalt liquids are products of crystal-liquid separation at low pressure. Primary status for these common basalts is further denied by the phase equilibria of such compositions at elevated pressures, when the required residual mantle mineralogy (magnesian olivine and orthopyroxene) is not stable at the liquidus. It is also denied by the picritic or komatiitic nature of partial melts of candidate upper-mantle compositions at high pressures - a conclusion supported by calculation of the melt composition, which would need to be extracted in order to explain the chemical variation between fertile and residual peridotite in natural ultramafic rock suites. The subtleties of magma chamber partial crystallization processes can produce an astounding array of "pseudospidergrams," a small selection of which have been explored here. Major modification of the trace element geochemistry and trace element ratios, even those of the highly incompatible elements, must always be entertained whenever the evidence suggests the possibility of partial crystallization. At one extreme, periodically recharged, periodically tapped magma chambers might undergo partial crystallization by ˜95% consolidation of a succession of small packets of the magma. Refluxing of the 5% residual melts from such a process into the main body of melt would lead to eventual discrimination between highly incompatible elements in that residual liquid comparable with that otherwise achieved by 0.1 to 0.3% liquid extraction in equilibrium partial melting. Great caution needs to be exercised in attempting the reconstruction of more primitive compositions by addition of troctolite, gabbro, and olivine to apparently primitive lava compositions. Special attention is focussed on the phase equilibria involving olivine, plagioclase (i.e., troctolite), and liquid because a high proportion of erupted basalts carry these two phases as phenocrysts, yet the equilibria are restricted to crustal pressures and are only encountered by wide ranges of basaltic compositions at pressures less than 0.5 GPa. The mere presence of plagioclase phenocrysts may be sufficient to disqualify candidate primitive magmas. Determination of the actual contributions of crustal processes to petrogenesis requires a return to detailed field, experimental, and forensic petrologic studies of individual erupted basalt flows; of a multitude of cumulate gabbros and their contacts; and of upper-mantle outcrops.

Just a Fad? Gamification in Health and Fitness Apps

PubMed Central

2014-01-01

Background Gamification has been a predominant focus of the health app industry in recent years. However, to our knowledge, there has yet to be a review of gamification elements in relation to health behavior constructs, or insight into the true proliferation of gamification in health apps. Objective The objective of this study was to identify the extent to which gamification is used in health apps, and analyze gamification of health and fitness apps as a potential component of influence on a consumer’s health behavior. Methods An analysis of health and fitness apps related to physical activity and diet was conducted among apps in the Apple App Store in the winter of 2014. This analysis reviewed a sample of 132 apps for the 10 effective game elements, the 6 core components of health gamification, and 13 core health behavior constructs. A regression analysis was conducted in order to measure the correlation between health behavior constructs, gamification components, and effective game elements. Results This review of the most popular apps showed widespread use of gamification principles, but low adherence to any professional guidelines or industry standard. Regression analysis showed that game elements were associated with gamification (P<.001). Behavioral theory was associated with gamification (P<.05), but not game elements, and upon further analysis gamification was only associated with composite motivational behavior scores (P<.001), and not capacity or opportunity/trigger. Conclusions This research, to our knowledge, represents the first comprehensive review of gamification use in health and fitness apps, and the potential to impact health behavior. The results show that use of gamification in health and fitness apps has become immensely popular, as evidenced by the number of apps found in the Apple App Store containing at least some components of gamification. This shows a lack of integrating important elements of behavioral theory from the app industry, which can potentially impact the efficacy of gamification apps to change behavior. Apps represent a very promising, burgeoning market and landscape in which to disseminate health behavior change interventions. Initial results show an abundant use of gamification in health and fitness apps, which necessitates the in-depth study and evaluation of the potential of gamification to change health behaviors. PMID:25654660

Stochastic sensing through covalent interactions

DOEpatents

Bayley, Hagan; Shin, Seong-Ho; Luchian, Tudor; Cheley, Stephen

2013-03-26

A system and method for stochastic sensing in which the analyte covalently bonds to the sensor element or an adaptor element. If such bonding is irreversible, the bond may be broken by a chemical reagent. The sensor element may be a protein, such as the engineered P.sub.SH type or .alpha.HL protein pore. The analyte may be any reactive analyte, including chemical weapons, environmental toxins and pharmaceuticals. The analyte covalently bonds to the sensor element to produce a detectable signal. Possible signals include change in electrical current, change in force, and change in fluorescence. Detection of the signal allows identification of the analyte and determination of its concentration in a sample solution. Multiple analytes present in the same solution may be detected.

Sensory aspects of trail-following behaviors in the Asian longhorned beetle, anoplophora glabripennis

USDA-ARS?s Scientific Manuscript database

Anoplophora glabripennis has a complex suite of mate-finding behaviors, the functions of which are not entirely understood. These behaviors are elicited by a number of factors, including visual and chemical cues. Chemical cues include a male-produced volatile semiochemical acting as a long-range sex...

The behavior of U- and Th-series nuclides in groundwater

USGS Publications Warehouse

Porcelli, D.; Swarzenski, P.W.

2003-01-01

Groundwater has long been an active area of research driven by its importance both as a societal resource and as a component in the global hydrological cycle. Key issues in groundwater research include inferring rates of transport of chemical constituents, determining the ages of groundwater, and tracing water masses using chemical fingerprints. While information on the trace elements pertinent to these topics can be obtained from aquifer tests using experimentally introduced tracers, and from laboratory experiments on aquifer materials, these studies are necessarily limited in time and space. Regional studies of aquifers can focus on greater scales and time periods, but must contend with greater complexities and variations. In this regard, the isotopic systematics of the naturally occurring radionuclides in the U- and Th- decay series have been invaluable in investigating aquifer behavior of U, Th, and Ra. These nuclides are present in all groundwaters and are each represented by several isotopes with very different half-lives, so that processes occurring over a range of time-scales can be studied (Table 1⇓). Within the host aquifer minerals, the radionuclides in each decay series are generally expected to be in secular equilibrium and so have equal activities (see Bourdon et al. 2003). In contrast, these nuclides exhibit strong relative fractionations within the surrounding groundwaters that reflect contrasting behavior during release into the water and during interaction with the surrounding host aquifer rocks. Radionuclide data can be used, within the framework of models of the processes involved, to obtain quantitative assessments of radionuclide release from aquifer rocks and groundwater migration rates. The isotopic variations that are generated also have the potential for providing fingerprints for groundwaters from specific aquifer environments, and have even been explored as a means for calculating groundwater ages.

Multiple populations in more metal-rich galactic globular clusters

NASA Astrophysics Data System (ADS)

Cordero, Maria J.

In this thesis we present chemical abundances for bright stars in the intermediate metallicity globular cluster (GC) M5, and the relatively metal-rich GCs M71 and 47 Tuc with the goal of improving the understanding of chemical evolution in the metallicity regime sampled by these three GCs. The first chapter presents a brief historical overview in light element abundance variations in globular clusters. In the second chapter we present the results obtained for 47 Tuc, the most-metal rich cluster of my sample. 47 Tuc is an ideal target to study chemical evolution and GC formation in massive more metal-rich GCs since it is the closest massive GC. Chemical abundances for O, Na, Al, Si, Ca, Ti, Fe, Ni, La, and Eu were determined for 164 red giant branch (RGB) stars in 47 Tuc using spectra obtained with both the Hydra multi-fiber spectrograph at the Blanco 4-m telescope and the FLAMES multi-object spectrograph at the ESO Very Large Telescope. The average [Fe/H]= --0.79+/-0.09 dex is consistent with literature values, as well as over-abundances of alpha-elements ([alpha/Fe] ~ 0.3 dex). The n-capture process elements indicate that 47 Tuc is r-process dominated ([Eu/La]=+0.24), and the light elements O, Na, and Al exhibit star-to-star variations. The Na-O anti-correlation, a signature typically seen in Galactic GCs, is present in 47 Tuc, and extends to include a small number of stars with [O/Fe] ~ --0.5. Additionally, the [O/Na] ratios of our sample reveal that the cluster stars can be separated into three distinct populations. A KS-test demonstrates that the O-poor/Na-rich stars are more centrally concentrated than the O-rich/Na-poor stars. The observed number and radial distribution of 47 Tuc's stellar populations, as distinguished by their light element composition, agrees closely with the results obtained from photometric data. We do not find evidence supporting a strong Na-Al correlation in 47 Tuc, which is consistent with current models of AGB nucleosynthesis yields. Aluminum is the heaviest light element displaying large star-to-star variations in Galactic GCs. This element may provide additional insight into the origin of the multiple populations and the nature of the first-generation stars responsible for chemical inhomogeneities. We found that, unlike more metal-poor GCs, 47 Tuc did not exhibit a strong Na-Al correlation, which motivates a careful study of the similar metallicity but less massive GC M71. In chapter 3, we present chemical abundances of O, Na, Al, and Fe for 33 giants in M71 using spectra obtained with the WIYN-Hydra spectrograph. Our spectroscopic analysis finds that, similar to 47 Tuc and in contrast with more metal-poor GCs, M71 stars do not exhibit a strong Na-Al correlation and span a relatively narrow range in [Al/Fe]. Furthermore, these data suggest that only a small fraction of stars (29%) have an [Na/Fe] ratio similar to halo stars at this metallicity, which is a characteristic reproduced by GC formation and evolution models. In the fourth chapter we present chemical abundances for a sample of 61 red giants in the intermediate-metallicity GC M5. The data were obtained using the Hydra multi-fiber positioner and bench spectrograph on the WIYN telescope. We find that our abundance ratios for Na, Al, Si, Ca, Ti, Fe, Ni, La, and Eu agree with published values for this cluster. The scatter seen in Fe-peak, alpha, and neutron-capture elements is consistent with typical spectroscopic errors. However, we identified a star modestly enhanced in La by performing a careful comparison of stellar spectra with similar atmospheric parameters. La-enhanced stars are rare in GCs. For instance, we have found only one such star in each of M5 and 47 Tuc. M5 red giants exhibit a strong Na-Al correlation, which is absent in M71 and 47 Tuc. Furthermore, M5 is at the metallicity regime where GCs seem to transition from small to large [Al/Fe] scatter. Interestingly, this metallicity regime also separates metal-poor from metal-rich Galactic GCs. In the fifth chapter we present radial distributions, population fractions, detailed examination of behavior of Al in more metal-rich GCs in the context of cluster chemical evolution, and, finally, a kinematical study of the GC M13 using spectra acquired with the WIYN-Hydra spectrograph. We find a rotational signal and a kinematical difference between the intermediate and extreme generations. Specifically, we find that the extreme O-depleted population, which is also more centrally concentrated than the primordial and intermediate populations, has the highest rotational amplitude. (Abstract shortened by UMI.)

Separation of mixtures of chemical elements in plasma

NASA Astrophysics Data System (ADS)

Dolgolenko, D. A.; Muromkin, Yu A.

2017-10-01

This paper reviews proposals on the plasma processing of radioactive waste (RW) and spent nuclear fuel (SNF). The chemical processing of SNF based on the extraction of its components from water solutions is rather expensive and produces new waste. The paper considers experimental research on plasma separation of mixtures of chemical elements and isotopes, whose results can help evaluate the plasma methods of RW and SNF reprocessing. The analysis identifies the difference between ionization levels of RW and SNF components at their transition to the plasma phase as a reason why all plasma methods are difficult to apply.

THEORETICAL Computations of Equilibrium Compositions, Thermodynamic Properties, and Performance Characteristics of Propellant Systems

DTIC Science & Technology

1979-04-01

U5 7 450o NITRATE 5h 3,4 -V -932 457 NITRIC ACID WuAS) lh IN 30 -509 .00lu 45t 43 NWC TP 6037 N,’TRO AM INI.GUA iiI u It, E1 51 h S5N 20 45 .COOO...and performance characteristics of propellant systems, and it will handle a maximum of 12 chemical elements and 200 combustion products . Some of the...used in the program, which will handle a maximum of 12 chemical elements and 200 combustion products . Flame temperature, chemical composition, enthalpy

Integrated Substrate and Thin Film Design Methods

DTIC Science & Technology

1999-02-01

Proper Representation Once the required chemical databases had been converted to the Excel format, VBA macros were written to convert chemical...ternary systems databases were imported from MS Excel to MS Access to implement SQL queries. Further, this database was connected via an ODBC model, to the... VBA macro, corresponding to each of the elements A, B, and C, respectively. The B loop began with the next alphabetical choice of element symbols

Social background of the discovery and the reception of the periodic law of the elements: recognizing the contributions of Dmitri Ivanovich Mendeleev and Julius Lothar Meyer.

PubMed

Kaji, Masanori

2003-05-01

The favorable and relatively rapid reception of Mendeleev's periodic table of the elements can be attributed, in part at least, to his social connections. These connections were evident in the recently organized Russian Chemical Society. In addition, Mendeleev enjoyed the support of the editorial board of the journal of the German Chemical Society.

Elemental compositions of crab and snail shells from the Kueishantao hydrothermal field in the southwestern Okinawa Trough

NASA Astrophysics Data System (ADS)

Zeng, Zhigang; Ma, Yao; Wang, Xiaoyuan; Chen, Chen-Tung Arthur; Yin, Xuebo; Zhang, Suping; Zhang, Junlong; Jiang, Wei

2018-04-01

To reveal differences in the behavior of benthic vent animals, and the sources and sinks of biogeochemical and fluid circulations, it is necessary to constrain the chemical characteristics of benthic animals from seafloor hydrothermal fields. We measured the abundances of 27 elements in shells of the crab Xenograpsus testudinatus and the snail Anachis sp., collected from the Kueishantao hydrothermal field (KHF) in the southwestern Okinawa Trough, with the aim of improving our understanding of the compositional variations between individual vent organisms, and the sources of the rare earth elements (REEs) in their shells. The Mn, Hg, and K concentrations in the male X. testudinatus shells are found to be higher than those in female crab shells, whereas the reverse is true for the accumulation of B, implying that the accumulation of K, Mn, Hg, and B in the crab shells is influenced by sex. This is inferred to be a result of the asynchronous molting of the male and female crab shells. Snail shells are found to have higher Ca, Al, Fe, Ni, and Co concentrations than crab shells. This may be attributed to different metal accumulation times. The majority of the light rare earth element (LREE) distribution patterns in the crab and snail shells are similar to those of Kueishantao vent fluids, with the crab and snail shells also exhibiting LREE enrichment, implying that the LREEs contained in crab and snail shells in the KHF are derived from vent fluids.

Synchrotron imaging reveals bone healing and remodelling strategies in extinct and extant vertebrates

PubMed Central

Anné, Jennifer; Edwards, Nicholas P.; Wogelius, Roy A.; Tumarkin-Deratzian, Allison R.; Sellers, William I.; van Veelen, Arjen; Bergmann, Uwe; Sokaras, Dimosthenis; Alonso-Mori, Roberto; Ignatyev, Konstantin; Egerton, Victoria M.; Manning, Phillip L.

2014-01-01

Current understanding of bone healing and remodelling strategies in vertebrates has traditionally relied on morphological observations through the histological analysis of thin sections. However, chemical analysis may also be used in such interpretations, as different elements are known to be absorbed and used by bone for different physiological purposes such as growth and healing. These chemical signatures are beyond the detection limit of most laboratory-based analytical techniques (e.g. scanning electron microscopy). However, synchrotron rapid scanning–X-ray fluorescence (SRS–XRF) is an elemental mapping technique that uniquely combines high sensitivity (ppm), excellent sample resolution (20–100 µm) and the ability to scan large specimens (decimetre scale) approximately 3000 times faster than other mapping techniques. Here, we use SRS–XRF combined with microfocus elemental mapping (2–20 µm) to determine the distribution and concentration of trace elements within pathological and normal bone of both extant and extinct archosaurs (Cathartes aura and Allosaurus fragilis). Results reveal discrete chemical inventories within different bone tissue types and preservation modes. Chemical inventories also revealed detail of histological features not observable in thin section, including fine structures within the interface between pathological and normal bone as well as woven texture within pathological tissue. PMID:24806709

Distribution of trace elements in certain ecological components and animal products in a dairy farm at Tirupati, Chittoor District, Andhra Pradesh, India.

PubMed

Raghu, V

2013-12-01

Biogeochemical characteristics of the cattle are dealt based on the observations made in Ayurveda in the light of modern scientific developments in applied environmental geochemistry. The biogeochemical characteristics of certain important ecological components and animal products of the stall-fed animals were studied. For this purpose, a dairy farm of Tirumala-Tirupati Devasthanams, a religious organization in Tirupati, Chittoor District, Andhra Pradesh was selected. This study is intended to trace out the trace element interactions in the ecological components (soil, water, fodder, feed) of the stall-fed animals and their output components viz. dung, urine and milk. Physical, physico-chemical properties and certain trace elements were determined for composite samples of ecological components and dung, urine, and milk of stall-fed animals. The variations in the distribution of pH and EC of urine and milk reflect the variations in their physico-chemical or hydro-chemical properties. As mentioned in Ayurveda, not only the properties of milk but also the properties of dung and urine reflect their diet and conditions of their habitat. Even though the diet is the same, the cows of different breeds yield milk of variable physical, physico-chemical properties and trace element composition which can be attributed to their body colour, substantiating Ayurveda.

The Natural Selection of the Chemical Elements (by R. J. P. Williams and J. J. R. Fraústo da Silva)

NASA Astrophysics Data System (ADS)

Kauffman, George B.

1998-12-01

Clarendon: New York, 1996. xxvi + 646 pp. Figs., tables. 20.5 x 25.6 cm. ISBN 0-19-855843-0. $80.00. R. J. P. Williams, Royal Society Research Professor Emeritus at Wadham College, Oxford University, and J. J. R. Fraústo da Silva, Professor of Analytical Chemistry at the Instituto Superior Técnico, Universidade Técnica de Lisboa, have collaborated on two previous volumes: New Trends in Bio-inorganic Chemistry (1978) and The Biological Chemistry of the Elements (3rd printing, 1994). Their latest collaborative effort is a book whose ambitious objective is "to show the relationship of every kind of material around us, living and nonliving, to the properties of the chemical elements of the periodic table." The "natural selection" of the chemical elements results from a number of factors, all of which are described in detail. Among these are chemical affinity related to the electronic configuration of their atoms, thermodynamic and kinetic stability, and "functional value to an organisation such as a living system". The physicist's approach to material through phase structure and the phase rule is stressed rather than the chemist's approach through bonding theories. The entire book possesses a strong environmental and interdisciplinary emphasis.

ORNL, partners officially recognized for discovery of elements 115, 117

ScienceCinema

Roberto, Jim

2018-01-16

The International Union for Pure and Applied Chemistry has announced formal verification of four new chemical elements, recognizing the Department of Energy’s Oak Ridge National Laboratory and its collaborators for the discovery of elements 115 and 117.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yushchenko, Alexander V.; Kang, Young-Woon; Kim, Sungeun

We investigated the chemical composition of ρ Pup using high-resolution spectral observations taken from the Very Large Telescope and the IUE archives and also spectra obtained at the 1.8 m telescope of the Bohyunsan observatory in Korea. The abundances of 56 chemical elements and the upper limits of Li and Be abundances were determined. The abundance pattern of ρ Pup was found to be similar to that of Am-type stars. The possibility of the influence of the accretion of interstellar gas and dust on the abundance patterns of B–F-type stars is discussed. The plots of the relative abundances of chemicalmore » elements in the atmospheres of ρ Pup and δ Sct versus the second ionization potentials of these elements show the correlations. The discontinuities at 13.6 and 24.6 eV—the ionization potentials of hydrogen and helium, respectively, are also exhibited in these plots. These discontinuities can be explained by interaction of the atoms of interstellar gas, mainly hydrogen and helium atoms, with the atoms of stellar photospheres (so-called charge-exchange reactions). Note that only the jumps near 13.6 and 24.6 eV were pointed out in previous investigations of relative abundances versus the second ionization potentials for Am-type stars. The dependencies of the relative abundances of chemical elements on the second ionization potentials of these elements were investigated using the published abundance patterns of B–F-type stars. The correlations of relative and absolute abundances of chemical elements, second ionization potentials, and projected rotational velocities are clearly detected for stars with effective temperatures between 7,000 and 12,000 K. If the correlation of relative abundances and second ionization potentials can be explained by the accretion of interstellar gas on the stellar surfaces, the investigation of these correlations can provide valuable information on the density and velocities of interstellar gas in different regions of the Galaxy and also on the influence of this phenomenon on stellar evolution. The dependencies of the relative abundances of chemical elements on the condensation temperatures of these elements were also found in the atmospheres of ρ Pup, δ Sct, and other B–F-type stars. Ten possible λ Boo-type stars were detected. The effective temperatures of these objects are between 10,900 and 14,000 K.« less

Facile Fabrication and Characterization of a PDMS-Derived Candle Soot Coated Stable Biocompatible Superhydrophobic and Superhemophobic Surface.

PubMed

Iqbal, R; Majhy, B; Sen, A K

2017-09-13

We report a simple, inexpensive, rapid, and one-step method for the fabrication of a stable and biocompatible superhydrophobic and superhemophobic surface. The proposed surface comprises candle soot particles embedded in a mixture of PDMS+n-hexane serving as the base material. The mechanism responsible for the superhydrophobic behavior of the surface is explained, and the surface is characterized based on its morphology and elemental composition, wetting properties, mechanical and chemical stability, and biocompatibility. The effect of %n-hexane in PDMS, the thickness of the PDMS+n-hexane layer (in terms of spin coating speed) and sooting time on the wetting property of the surface is studied. The proposed surface exhibits nanoscale surface asperities (average roughness of 187 nm), chemical compositions of soot particles, very high water and blood repellency along with excellent mechanical and chemical stability and excellent biocompatibility against blood sample and biological cells. The water contact angle and roll-off angle is measured as 160° ± 1° and 2°, respectively, and the blood contact angle is found to be 154° ± 1°, which indicates that the surface is superhydrophobic and superhemophobic. The proposed superhydrophobic and superhemophobic surface offers significantly improved (>40%) cell viability as compared to glass and PDMS surfaces.

Effects of removal of different chemical components on moisture sorption property of Populus euramericana Cv. under dynamic hygrothermal conditions

NASA Astrophysics Data System (ADS)

Yang, Tiantian; Zhou, Haizhen; Ma, Erni; Wang, Jiamin

2018-09-01

Effects of chemical components on wood sorption property under dynamic condition were investigated for the first time. Hemicellulose, lignin and extractive (denoted as DHC, DL and DE, respectively) were removed from Populus euramericana Cv., 20 mm in radial (R) and tangential (T) directions with thickness of 4 mm along the grain, then the wood was subjected to cyclic tests where relative humidity (RH) varied from 45% to 75% sinusoidally at 25 °C. Based on measured data automatically, the results showed that, various chemical components had different effects on dynamic sorption behaviors of wood. The DL exhibited the largest moisture content and diffusion coefficient, followed by the DE, Control and DHC. This indicated lignin or extractive removal accelerated the dynamic sorption process and improved hygroscopicity of wood, while hemicellulose removal caused opposite effects. Theoretical sorption model was further applied and the modeled curves fitted satisfactorily with experimental data. Dynamic moisture gradient distribution inside the different treated wood was investigated and amplitude of moisture showed negative relation with wood element depth, while phase lag presented an opposite trend. Amplitude of DL was the largest while its phase lag was the least. Conditioning thickness for RH was greatest for DHC, about twice as much as the minimum of DL.

Excimer-laser-induced surface treatments on metal and ceramic materials: applications to automotive, aerospace, and microelectronic industries

NASA Astrophysics Data System (ADS)

Autric, Michel L.

1999-09-01

Surface treatments by laser irradiation can improve materials properties in terms of mechanical and physico- chemical behaviors, these improvements being related to the topography, the hardness, the microstructure, the chemical composition. Up to now, the use of excimer lasers for industrial applications remained marginal in spite of the interest related to the short wavelength (high photon energy and better energetic coupling with materials and reduced thermal effects in the bulk material). Up to now, the main limitations concerned the beam quality, the beam delivery, the gas handling and the relatively high investment cost. At this time, the cost of laser devices is going down and the ultraviolet radiation can be conducted through optical fibers. These two elements give new interest in using excimer laser for industrial applications. The main objective of this research program which we are involved in, is to underline some materials processing applications for automotive, aerospace or microelectronic industries for which it could be more interesting to use excimer lasers (minimized thermal effects). This paper concerns the modifications of the roughness, porosity, hardness, structure, phase, residual stresses, chemical composition of the surface of materials such as metallic alloys (aluminum, steel, cast iron, titanium, and ceramics (oxide, nitride, carbide,...) irradiated by KrF and XeCl excimer lasers.

Chemical and non-chemical stressors affecting childhood obesity: a systematic scoping review.

PubMed

Lichtveld, Kim; Thomas, Kent; Tulve, Nicolle S

2018-01-01

Childhood obesity in the United States has doubled over the last three decades and currently affects 17% of children and adolescents. While much research has focused on individual behaviors impacting obesity, little research has emphasized the complex interactions of numerous chemical and non-chemical stressors found in a child's environment and how these interactions affect a child's health and well-being. The objectives of this systematic scoping review were to (1) identify potential chemical stressors in the context of non-chemical stressors that impact childhood obesity; and, (2) summarize our observations for chemical and non-chemical stressors in regards to child-specific environments within a community setting. A review was conducted to identify chemical and non-chemical stressors related to childhood obesity for the childhood life stages ranging from prenatal to adolescence. Stressors were identified and grouped into domains: individual behaviors, family/household behaviors, community stressors, and chemical exposures. Stressors were related to the child and the child's everyday environments and used to characterize child health and well-being. This review suggests that the interactions of chemical and non-chemical stressors are important for understanding a child's overall health and well-being. By considering these relationships, the exposure science research community can better design and implement strategies to reduce childhood obesity.

Determination of low-Z elements in individual environmental particles using windowless EPMA.

PubMed

Ro, C U; Osán, J; Van Grieken, R

1999-04-15

The determination of low-Z elements such as carbon, nitrogen, and oxygen in atmospheric aerosol particles is of interest in studying environmental pollution. Conventional electron probe microanalysis technique has a limitation for the determination of the low-Z elements, mainly because the Be window in an energy-dispersive X-ray (EDX) detector hinders the detection of characteristic X-rays from light elements. The feasibility of low-Z element determination in individual particles using a windowless EDX detector is investigated. To develop a method capable of identifying chemical species of individual particles, both the matrix and the geometric effects of particles have to be evaluated. X-rays of low-Z elements generated by an electron beam are so soft that important matrix effects, mostly due to X-ray absorption, exist even within particles in the micrometer size range. Also, the observed radiation, especially that of light elements, experiences different extents of absorption, depending on the shape and size of the particles. Monte Carlo calculation is applied to explain the variation of observed X-ray intensities according to the geometric and chemical compositional variation of individual particles, at different primary electron beam energies. A comparison is carried out between simulated and experimental data, collected for standard individual particles with chemical compositions as generally observed in marine and continental aerosols. Despite the many fundamental problematic analytical factors involved in the observation of X-rays from low-Z elements, the Monte Carlo calculation proves to be quite reliable to evaluate those matrix and geometric effects. Practical aspects of the Monte Carlo calculation for the determination of light elements in individual particles are also considered.

Experimental data showing the thermal behavior of a flat roof with phase change material.

PubMed

Tokuç, Ayça; Başaran, Tahsin; Yesügey, S Cengiz

2015-12-01

The selection and configuration of building materials for optimal energy efficiency in a building require some assumptions and models for the thermal behavior of the utilized materials. Although the models for many materials can be considered acceptable for simulation and calculation purposes, the work for modeling the real time behavior of phase change materials is still under development. The data given in this article shows the thermal behavior of a flat roof element with a phase change material (PCM) layer. The temperature and energy given to and taken from the building element are reported. In addition the solid-liquid behavior of the PCM is tracked through images. The resulting thermal behavior of the phase change material is discussed and simulated in [1] A. Tokuç, T. Başaran, S.C. Yesügey, An experimental and numerical investigation on the use of phase change materials in building elements: the case of a flat roof in Istanbul, Build. Energy, vol. 102, 2015, pp. 91-104.

10 CFR Appendix A to Part 725 - Categories of Restricted Data Available

Code of Federal Regulations, 2013 CFR

2013-01-01

... and radiation studies. b. Chemistry, chemical engineering and radiochemistry of all the elements and their compounds. Included are techniques and processes of chemical separations, radioactive waste..., including chemical engineering, processes and techniques. Reactor physics, engineering and criticality...

Finite element simulation of articular contact mechanics with quadratic tetrahedral elements.

PubMed

Maas, Steve A; Ellis, Benjamin J; Rawlins, David S; Weiss, Jeffrey A

2016-03-21

Although it is easier to generate finite element discretizations with tetrahedral elements, trilinear hexahedral (HEX8) elements are more often used in simulations of articular contact mechanics. This is due to numerical shortcomings of linear tetrahedral (TET4) elements, limited availability of quadratic tetrahedron elements in combination with effective contact algorithms, and the perceived increased computational expense of quadratic finite elements. In this study we implemented both ten-node (TET10) and fifteen-node (TET15) quadratic tetrahedral elements in FEBio (www.febio.org) and compared their accuracy, robustness in terms of convergence behavior and computational cost for simulations relevant to articular contact mechanics. Suitable volume integration and surface integration rules were determined by comparing the results of several benchmark contact problems. The results demonstrated that the surface integration rule used to evaluate the contact integrals for quadratic elements affected both convergence behavior and accuracy of predicted stresses. The computational expense and robustness of both quadratic tetrahedral formulations compared favorably to the HEX8 models. Of note, the TET15 element demonstrated superior convergence behavior and lower computational cost than both the TET10 and HEX8 elements for meshes with similar numbers of degrees of freedom in the contact problems that we examined. Finally, the excellent accuracy and relative efficiency of these quadratic tetrahedral elements was illustrated by comparing their predictions with those for a HEX8 mesh for simulation of articular contact in a fully validated model of the hip. These results demonstrate that TET10 and TET15 elements provide viable alternatives to HEX8 elements for simulation of articular contact mechanics. Copyright © 2016 Elsevier Ltd. All rights reserved.

Image-based Modeling of Biofilm-induced Calcium Carbonate Precipitation

NASA Astrophysics Data System (ADS)

Connolly, J. M.; Rothman, A.; Jackson, B.; Klapper, I.; Cunningham, A. B.; Gerlach, R.

2013-12-01

Pore scale biological processes in the subsurface environment are important to understand in relation to many engineering applications including environmental contaminant remediation, geologic carbon sequestration, and petroleum production. Specifically, biofilm induced calcium carbonate precipitation has been identified as an attractive option to reduce permeability in a lasting way in the subsurface. This technology may be able to replace typical cement-based grouting in some circumstances; however, pore-scale processes must be better understood for it to be applied in a controlled manor. The work presented will focus on efforts to observe biofilm growth and ureolysis-induced mineral precipitation in micro-fabricated flow cells combined with finite element modelling as a tool to predict local chemical gradients of interest (see figure). We have been able to observe this phenomenon over time using a novel model organism that is able to hydrolyse urea and express a fluorescent protein allowing for non-invasive observation over time with confocal microscopy. The results of this study show the likely existence of a wide range of local saturation indices even in a small (1 cm length scale) experimental system. Interestingly, the locations of high predicted index do not correspond to the locations of higher precipitation density, highlighting the need for further understanding. Figure 1 - A micro-fabricated flow cell containing biofilm-induced calcium carbonate precipitation. (A) Experimental results: Active biofilm is in green and dark circles are calcium carbonate crystals. Note the channeling behavior in the top of the image, leaving a large hydraulically inactive area in the biofilm mass. (B) Finite element model: The prediction of relative saturation of calcium carbonate (as calcite). Fluid enters the system at a low saturation state (blue) but areas of high supersaturation (red) are predicted within the hydraulically inactive area in the biofilm. If only effluent saturation was measured, precipitation may not even be predicted but we see local, pore-scale behavior dictating system behavior in this case. The flow cell is 1 cm in length and the porous media elements are 100 μm.

Obtaining 3D Chemical Maps by Energy Filtered Transmission Electron Microscopy Tomography.

PubMed

Roiban, Lucian; Sorbier, Loïc; Hirlimann, Charles; Ersen, Ovidiu

2018-06-09

Energy filtered transmission electron microscopy tomography (EFTEM tomography) can provide three-dimensional (3D) chemical maps of materials at a nanometric scale. EFTEM tomography can separate chemical elements that are very difficult to distinguish using other imaging techniques. The experimental protocol described here shows how to create 3D chemical maps to understand the chemical distribution and morphology of a material. Sample preparation steps for data segmentation are presented. This protocol permits the 3D distribution analysis of chemical elements in a nanometric sample. However, it should be noted that currently, the 3D chemical maps can only be generated for samples that are not beam sensitive, since the recording of filtered images requires long exposure times to an intense electron beam. The protocol was applied to quantify the chemical distribution of the components of two different heterogeneous catalyst supports. In the first study, the chemical distribution of aluminum and titanium in titania-alumina supports was analyzed. The samples were prepared using the swing-pH method. In the second, the chemical distribution of aluminum and silicon in silica-alumina supports that were prepared using the sol-powder and mechanical mixture methods was examined.

The statistics of Pearce element diagrams and the Chayes closure problem

NASA Astrophysics Data System (ADS)

Nicholls, J.

1988-05-01

Pearce element ratios are defined as having a constituent in their denominator that is conserved in a system undergoing change. The presence of a conserved element in the denominator simplifies the statistics of such ratios and renders them subject to statistical tests, especially tests of significance of the correlation coefficient between Pearce element ratios. Pearce element ratio diagrams provide unambigous tests of petrologic hypotheses because they are based on the stoichiometry of rock-forming minerals. There are three ways to recognize a conserved element: 1. The petrologic behavior of the element can be used to select conserved ones. They are usually the incompatible elements. 2. The ratio of two conserved elements will be constant in a comagmatic suite. 3. An element ratio diagram that is not constructed with a conserved element in the denominator will have a trend with a near zero intercept. The last two criteria can be tested statistically. The significance of the slope, intercept and correlation coefficient can be tested by estimating the probability of obtaining the observed values from a random population of arrays. This population of arrays must satisfy two criteria: 1. The population must contain at least one array that has the means and variances of the array of analytical data for the rock suite. 2. Arrays with the means and variances of the data must not be so abundant in the population that nearly every array selected at random has the properties of the data. The population of random closed arrays can be obtained from a population of open arrays whose elements are randomly selected from probability distributions. The means and variances of these probability distributions are themselves selected from probability distributions which have means and variances equal to a hypothetical open array that would give the means and variances of the data on closure. This hypothetical open array is called the Chayes array. Alternatively, the population of random closed arrays can be drawn from the compositional space available to rock-forming processes. The minerals comprising the available space can be described with one additive component per mineral phase and a small number of exchange components. This space is called Thompson space. Statistics based on either space lead to the conclusion that Pearce element ratios are statistically valid and that Pearce element diagrams depict the processes that create chemical inhomogeneities in igneous rock suites.

Using Temperature-Dependent Phenomena at Oxide Surfaces for Species Recognition in Chemical Sensing.

NASA Astrophysics Data System (ADS)

Semancik, Steve; Meier, Douglas; Evju, Jon; Benkstein, Kurt; Boger, Zvi; Montgomery, Chip

2006-03-01

Nanostructured films of SnO2 and TiO2 have been deposited on elements in MEMS arrays to fabricate solid state conductometric gas microsensors. The multilevel platforms within an array, called microhotplates, are individually addressable for localized temperature control and measurement of sensing film electrical conductance. Temperature variations of the microhotplates are employed in thermally-activated CVD oxide film growth, and for rapid temperature-programmed operation of the microsensors. Analytical information on environmental gas phase composition is produced temporally as purposeful thermal fluctuations provide energetic and kinetic control of surface reaction and adsorption/desorption phenomena. Resulting modulations of oxide adsorbate populations cause changing charge transfer behavior and measurable conductance responses. Rich data streams from different sensing films in the arrays have been analyzed by Artificial Neural Networks (ANN) to successfully recognize low concentration species in mixed gases. We illustrate capabilities of the approach and technology in the homeland security area, where dangerous chemicals (TICs, CWSs and CWAs) have been detected at 10-100 ppb levels in interference-spiked air backgrounds.

Cyclical nursing patterns in wild orangutans

PubMed Central

Smith, Tanya M.; Austin, Christine; Hinde, Katie; Vogel, Erin R.; Arora, Manish

2017-01-01

Nursing behavior is notoriously difficult to study in arboreal primates, particularly when offspring suckle inconspicuously in nests. Orangutans have the most prolonged nursing period of any mammal, with the cessation of suckling (weaning) estimated to occur at 6 to 8 years of age in the wild. Milk consumption is hypothesized to be relatively constant over this period, but direct evidence is limited. We previously demonstrated that trace element analysis of bioavailable elements from milk, such as barium, provides accurate estimates of early-life diet transitions and developmental stress when coupled with growth lines in the teeth of humans and nonhuman primates. We provide the first detailed nursing histories of wild, unprovisioned orangutans (Pongo abelii and Pongo pygmaeus) using chemical and histological analyses. Laser ablation inductively coupled plasma mass spectrometry was used to determine barium distributions across the teeth of four wild-shot individuals aged from postnatal biological rhythms. Barium levels rose during the first year of life in all individuals and began to decline shortly after, consistent with behavioral observations of intensive nursing followed by solid food supplementation. Subsequent barium levels show large sustained fluctuations on an approximately annual basis. These patterns appear to be due to cycles of varying milk consumption, continuing until death in an 8.8-year-old Sumatran individual. A female Bornean orangutan ceased suckling at 8.1 years of age. These individuals exceed the maximum weaning age reported for any nonhuman primate. Orangutan nursing may reflect cycles of infant demand that relate to fluctuating resource availability. PMID:28560319

Petroleomics: Chemistry of the underworld

PubMed Central

Marshall, Alan G.; Rodgers, Ryan P.

2008-01-01

Each different molecular elemental composition—e.g., CcHhNnOoSs—has a different exact mass. With sufficiently high mass resolving power (m/Δm50% ≈ 400,000, in which m is molecular mass and Δm50% is the mass spectral peak width at half-maximum peak height) and mass accuracy (<300 ppb) up to ≈800 Da, now routinely available from high-field (≥9.4 T) Fourier transform ion cyclotron resonance mass spectrometry, it is possible to resolve and identify uniquely and simultaneously each of the thousands of elemental compositions from the most complex natural organic mixtures, including petroleum crude oil. It is thus possible to separate and sort petroleum components according to their heteroatom class (NnOoSs), double bond equivalents (DBE = number of rings plus double bonds involving carbon, because each ring or double bond results in a loss of two hydrogen atoms), and carbon number. “Petroleomics” is the characterization of petroleum at the molecular level. From sufficiently complete characterization of the organic composition of petroleum and its products, it should be possible to correlate (and ultimately predict) their properties and behavior. Examples include molecular mass distribution, distillation profile, characterization of specific fractions without prior extraction or wet chemical separation from the original bulk material, biodegradation, maturity, water solubility (and oil:water emulsion behavior), deposits in oil wells and refineries, efficiency and specificity of catalytic hydroprocessing, “heavy ends” (asphaltenes) analysis, corrosion, etc. PMID:18836082

Petroleomics: chemistry of the underworld.

PubMed

Marshall, Alan G; Rodgers, Ryan P

2008-11-25

Each different molecular elemental composition-e.g., C(c)H(h)N(n)O(o)S(s)-has a different exact mass. With sufficiently high mass resolving power (m/Deltam(50%) approximately 400,000, in which m is molecular mass and Deltam(50%) is the mass spectral peak width at half-maximum peak height) and mass accuracy (<300 ppb) up to approximately 800 Da, now routinely available from high-field (>/=9.4 T) Fourier transform ion cyclotron resonance mass spectrometry, it is possible to resolve and identify uniquely and simultaneously each of the thousands of elemental compositions from the most complex natural organic mixtures, including petroleum crude oil. It is thus possible to separate and sort petroleum components according to their heteroatom class (N(n)O(o)S(s)), double bond equivalents (DBE = number of rings plus double bonds involving carbon, because each ring or double bond results in a loss of two hydrogen atoms), and carbon number. "Petroleomics" is the characterization of petroleum at the molecular level. From sufficiently complete characterization of the organic composition of petroleum and its products, it should be possible to correlate (and ultimately predict) their properties and behavior. Examples include molecular mass distribution, distillation profile, characterization of specific fractions without prior extraction or wet chemical separation from the original bulk material, biodegradation, maturity, water solubility (and oil:water emulsion behavior), deposits in oil wells and refineries, efficiency and specificity of catalytic hydroprocessing, "heavy ends" (asphaltenes) analysis, corrosion, etc.

Polarization transfer NMR imaging

DOEpatents

Sillerud, Laurel O.; van Hulsteyn, David B.

1990-01-01

A nuclear magnetic resonance (NMR) image is obtained with spatial information modulated by chemical information. The modulation is obtained through polarization transfer from a first element representing the desired chemical, or functional, information, which is covalently bonded and spin-spin coupled with a second element effective to provide the imaging data. First and second rf pulses are provided at first and second frequencies for exciting the imaging and functional elements, with imaging gradients applied therebetween to spatially separate the nuclei response for imaging. The second rf pulse is applied at a time after the first pulse which is the inverse of the spin coupling constant to select the transfer element nuclei which are spin coupled to the functional element nuclei for imaging. In a particular application, compounds such as glucose, lactate, or lactose, can be labeled with .sup.13 C and metabolic processes involving the compounds can be imaged with the sensitivity of .sup.1 H and the selectivity of .sup.13 C.

Chemical Dissolution of Simulant FCA Cladding and Plates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Daniel, G.; Pierce, R.; O'Rourke, P.

The Savannah River Site (SRS) has received some fast critical assembly (FCA) fuel from the Japan Atomic Energy Agency (JAEA) for disposition. Among the JAEA FCA fuel are approximately 7090 rectangular Stainless Steel clad fuel elements. Each element has an internal Pu-10.6Al alloy metal wafer. The thickness of each element is either 1/16 inch or 1/32 inch. The dimensions of each element ranges from 2 inches x 1 inch to 2 inches x 4 inches. This report discusses the potential chemical dissolution of the FCA clad material or stainless steel. This technology uses nitric acid-potassium fluoride (HNO 3-KF) flowsheets ofmore » H-Canyon to dissolve the FCA elements from a rack of materials. Historically, dissolution flowsheets have aimed to maximize Pu dissolution rates while minimizing stainless steel dissolution (corrosion) rates. Because the FCA cladding is made of stainless steel, this work sought to accelerate stainless steel dissolution.« less

Method for quantitative determination and separation of trace amounts of chemical elements in the presence of large quantities of other elements having the same atomic mass

DOEpatents

Miller, C.M.; Nogar, N.S.

1982-09-02

Photoionization via autoionizing atomic levels combined with conventional mass spectroscopy provides a technique for quantitative analysis of trace quantities of chemical elements in the presence of much larger amounts of other elements with substantially the same atomic mass. Ytterbium samples smaller than 10 ng have been detected using an ArF* excimer laser which provides the atomic ions for a time-of-flight mass spectrometer. Elemental selectivity of greater than 5:1 with respect to lutetium impurity has been obtained. Autoionization via a single photon process permits greater photon utilization efficiency because of its greater absorption cross section than bound-free transitions, while maintaining sufficient spectroscopic structure to allow significant photoionization selectivity between different atomic species. Separation of atomic species from others of substantially the same atomic mass is also described.

The use of elemental sulfur as an alternative feedstock for polymeric materials

NASA Astrophysics Data System (ADS)

Chung, Woo Jin; Griebel, Jared J.; Kim, Eui Tae; Yoon, Hyunsik; Simmonds, Adam G.; Ji, Hyun Jun; Dirlam, Philip T.; Glass, Richard S.; Wie, Jeong Jae; Nguyen, Ngoc A.; Guralnick, Brett W.; Park, Jungjin; Somogyi, Árpád; Theato, Patrick; Mackay, Michael E.; Sung, Yung-Eun; Char, Kookheon; Pyun, Jeffrey

2013-06-01

An excess of elemental sulfur is generated annually from hydrodesulfurization in petroleum refining processes; however, it has a limited number of uses, of which one example is the production of sulfuric acid. Despite this excess, the development of synthetic and processing methods to convert elemental sulfur into useful chemical substances has not been investigated widely. Here we report a facile method (termed ‘inverse vulcanization’) to prepare chemically stable and processable polymeric materials through the direct copolymerization of elemental sulfur with vinylic monomers. This methodology enabled the modification of sulfur into processable copolymer forms with tunable thermomechanical properties, which leads to well-defined sulfur-rich micropatterned films created by imprint lithography. We also demonstrate that these copolymers exhibit comparable electrochemical properties to elemental sulfur and could serve as the active material in Li-S batteries, exhibiting high specific capacity (823 mA h g-1 at 100 cycles) and enhanced capacity retention.

A damage mechanics based general purpose interface/contact element

NASA Astrophysics Data System (ADS)

Yan, Chengyong

Most of the microelectronics packaging structures consist of layered substrates connected with bonding materials, such as solder or epoxy. Predicting the thermomechanical behavior of these multilayered structures is a challenging task in electronic packaging engineering. In a layered structure the most complex part is always the interfaces between the strates. Simulating the thermo-mechanical behavior of such interfaces, is the main theme of this dissertation. The most commonly used solder material, Pb-Sn alloy, has a very low melting temperature 180sp°C, so that the material demonstrates a highly viscous behavior. And, creep usually dominates the failure mechanism. Hence, the theory of viscoplasticity is adapted to describe the constitutive behavior. In a multilayered assembly each layer has a different coefficient of thermal expansion. Under thermal cycling, due to heat dissipated from circuits, interfaces and interconnects experience low cycle fatigue. Presently, the state-of-the art damage mechanics model used for fatigue life predictions is based on Kachanov (1986) continuum damage model. This model uses plastic strain as a damage criterion. Since plastic strain is a stress path dependent value, the criterion does not yield unique damage values for the same state of stress. In this dissertation a new damage evolution equation based on the second law of thermodynamic is proposed. The new criterion is based on the entropy of the system and it yields unique damage values for all stress paths to the final state of stress. In the electronics industry, there is a strong desire to develop fatigue free interconnections. The proposed interface/contact element can also simulate the behavior of the fatigue free Z-direction thin film interconnections as well as traditional layered interconnects. The proposed interface element can simulate behavior of a bonded interface or unbonded sliding interface, also called contact element. The proposed element was verified against laboratory test data presented in the literature. The results demonstrate that the proposed element and the damage law perform very well. The most important scientific contribution of this dissertation is the proposed damage criterion based on second law of thermodynamic and entropy of the system. The proposed general purpose interface/contact element is another contribution of this research. Compared to the previous adhoc interface elements proposed in the literature, the new one is, much more powerful and includes creep, plastic deformations, sliding, temperature, damage, cyclic behavior and fatigue life in a unified formulation.

Chemical Solitaire

ERIC Educational Resources Information Center

Philippof, Joanna; Seraphin, Kanesa Duncan; Seki, Jennifer; Kaupp, Lauren

2015-01-01

The periodic table does more than provide information about the elements. The periodic table also helps us make predictions about how the elements behave. Understanding the atomic structure of matter and periodic properties of the elements, as shown in the periodic table, is fundamental to many scientific disciplines. Unfortunately, high school…

The New Element Curium (Atomic Number 96)

DOE R&D Accomplishments Database

Seaborg, G. T.; James, R. A.; Ghiorso, A.

1948-01-01

Two isotopes of the element with atomic number 96 have been produced by the helium-ion bombardment of plutonium. The name curium, symbol Cm, is proposed for element 96. The chemical experiments indicate that the most stable oxidation state of curium is the III state.

Sensory aspects of trail-following behaviors in the Asian longhorned beetle, Anoplophora glabripennis

Treesearch

Fern Graves; Thomas C. Baker; Aijun Zhang; Melody Keena; Kelli Hoover

2016-01-01

Anoplophora glabripennis has a complex suite of mate-finding behaviors, the functions of which are not entirely understood. These behaviors are elicited by a number of factors, including visual and chemical cues. Chemical cues include a maleproduced volatile semiochemical acting as a long-range sex pheromone, a femaleproduced cuticular hydrocarbon...

DOSE-RESPONSE BEHAVIOR OF ANDROGENIC AND ANTIANDROGENIC CHEMICALS: IMPLICATIONS FOR LOW-DOSE EXTRAPOLATION AND CUMULATIVE TOXICITY

EPA Science Inventory

DOSE-RESPONSE BEHAVIOR OF ANDROGENIC AND ANTIANDROGENIC CHEMICALS: IMPLICATIONS FOR LOW-DOSE EXTRAPOLATION AND CUMULATIVE TOXICITY. LE Gray Jr, C Wolf, J Furr, M Price, C Lambright, VS Wilson and J Ostby. USEPA, ORD, NHEERL, EB, RTD, RTP, NC, USA.
Dose-response behavior of a...

Multi-elemental imaging of paraffin-embedded human samples by laser-induced breakdown spectroscopy

NASA Astrophysics Data System (ADS)

Moncayo, S.; Trichard, F.; Busser, B.; Sabatier-Vincent, M.; Pelascini, F.; Pinel, N.; Templier, I.; Charles, J.; Sancey, L.; Motto-Ros, V.

2017-07-01

Chemical elements play central roles for physiological homeostasis in human cells, and their dysregulation might lead to a certain number of pathologies. Novel imaging techniques that improve the work of pathologists for tissue analysis and diagnostics are continuously sought. We report the use of Laser-Induced Breakdown Spectroscopy (LIBS) to perform multi-elemental images of human paraffin-embedded skin samples on the entire biopsy scale in a complementary and compatible way with microscope histopathological examination. A specific instrumental configuration is proposed in order to detect most of the elements of medical interest (i.e. P, Al, Mg, Na, Zn, Si, Fe, and Cu). As an example of medical application, we selected and analysed skin biopsies, including healthy skin tissue, cutaneous metastasis of melanoma, Merkel-cell carcinoma and squamous cell carcinoma. Clear distinctions in the distribution of chemical elements are observed from the different samples investigated. This study demonstrates the high complementarity of LIBS elemental imaging with conventional histopathology, opening new opportunities for any medical application involving metals.

The presence of vanadium in groundwater of southeastern extreme the pampean region Argentina Relationship with other chemical elements.

PubMed

Fiorentino, Carmen E; Paoloni, Juan D; Sequeira, Mario E; Arosteguy, Pedro

2007-08-15

Changes in the quality of groundwater resources are related to the presence and concentration of contaminants, especially trace elements such as arsenic, boron, fluoride and vanadium. Vanadium is a rare element naturally abundant, generally found in combination with other elements. Vanadium pentoxide is known to have aneugenic effects. Thus, a study was carried out to assess the presence of vanadium in the groundwater of the southeastern pampean region of Argentina, which constitutes the main water supply for the local population. Statistical and correlational analyses were applied to identify possible interrelationships between vanadium and another chemical elements. Vanadium was found in all groundwater samples. The minimum and maximum vanadium concentrations found were 0.05 mg/l and 2.47 mg/l, respectively. Vanadium is significantly correlated with other trace elements such as arsenic, fluoride and boron. The interrelationship between vanadium and the presence of volcanic glass in sediments is not significant as expected.

Delamination Behavior of L-Shaped Laminated Composites

NASA Astrophysics Data System (ADS)

Geleta, Tsinuel N.; Woo, Kyeongsik; Lee, Bongho

2018-05-01

We studied the delamination behavior of L-shaped laminated composites numerically and experimentally. In finite-element modeling, cohesive zone modeling was used to simulate the delamination of plies. Cohesive elements were inserted between bulk elements at each interlayer to represent the occurrence of multiple delaminations. The laminated composite models were subjected to several types of loading inducing opening and shearing types of delamination. Numerical results were compared to those in the literature and of experiments conducted in this study. The results were carefully examined to investigate diverse delamination initiation and propagation behaviors. The effect of varying presence and location of pre-crack was also studied.

Chemistry of diagenetically altered tuffs at a potential nuclear waste repository, Yucca Mountain, Nye County, Nevada

DOE Office of Scientific and Technical Information (OSTI.GOV)

Broxton, D.E.; Warren, R.G.; Hagan, R.C.

1986-10-01

The chemistry of diagenetically altered tuffs at a potential nuclear waste repository, Yucca Mountain, Nevada is described. These tuffs contain substantial amounts of zeolites that are highly sorptive of certain radionuclides. Because of their widespread distribution, the zeolitic tuffs could provide important barriers to radionuclide migration. Physical properties of these tuffs and of their constituent zeolites are influenced by their chemical compositions. This study defines the amount of chemical variability within diagenetically altered tuffs and within diagenetic minerals at Yucca Mountain. Zeolitic tuffs at Yucca Mountain formed by diagenetic alteration of rhyolitic vitric tuffs. Despite their similar starting compositions, thesemore » tuffs developed compositions that vary both vertically and laterally. Widespread chemical variations were the result of open-system chemical diagenesis in which chemical components of the tuffs were mobilized and redistributed by groundwaters. Alkalies, alkaline earths, and silica were the most mobile elements during diagenesis. The zeolitic tuffs can be divided into three compositional groups: (1) calcium- and magnesium-rich tuffs associated with relatively thin zones of alteration in the unsaturated zone; (2) tuffs in thick zones of alteration at and below the water table that grade laterally from sodic compositions on the western side of Yucca Mountain to calcic compositions on the eastern side; and (3) potassic tuffs at the north end of Yucca Mountain. Physical properties of tuffs and their consistuent zeolites at Yucca Mountain may be affected by variations in compositions. Properties important for assessment of repository performance include behavior and ion exchange.« less

Climate-driven thresholds for chemical weathering in postglacial soils of New Zealand

NASA Astrophysics Data System (ADS)

Dixon, Jean L.; Chadwick, Oliver A.; Vitousek, Peter M.

2016-09-01

Chemical weathering in soils dissolves and alters minerals, mobilizes metals, liberates nutrients to terrestrial and aquatic ecosystems, and may modulate Earth's climate over geologic time scales. Climate-weathering relationships are often considered fundamental controls on the evolution of Earth's surface and biogeochemical cycles. However, surprisingly little consensus has emerged on if and how climate controls chemical weathering, and models and data from published literature often give contrasting correlations and predictions for how weathering rates and climate variables such as temperature or moisture are related. Here we combine insights gained from the different approaches, methods, and theory of the soil science, biogeochemistry, and geomorphology communities to tackle the fundamental question of how rainfall influences soil chemical properties. We explore climate-driven variations in weathering and soil development in young, postglacial soils of New Zealand, measuring soil elemental geochemistry along a large precipitation gradient (400-4700 mm/yr) across the Waitaki basin on Te Waipounamu, the South Island. Our data show a strong climate imprint on chemical weathering in these young soils. This climate control is evidenced by rapid nonlinear changes along the gradient in total and exchangeable cations in soils and in the increased movement and redistribution of metals with rainfall. The nonlinear behavior provides insight into why climate-weathering relationships may be elusive in some landscapes. These weathering thresholds also have significant implications for how climate may influence landscape evolution and the release of rock-derived nutrients to ecosystems, as landscapes that transition to wetter climates across this threshold may weather and deplete rapidly.

Smells Like Home: Chemically Mediated Co-Habitation of Two Termite Species in a Single Nest.

PubMed

Jirošová, Anna; Sillam-Dussès, David; Kyjaková, Pavlína; Kalinová, Blanka; Dolejšová, Klára; Jančařík, Andrej; Majer, Pavel; Cristaldo, Paulo Fellipe; Hanus, Robert

2016-10-01

Termite nests often are referred to as the most elaborate constructions of animals. However, some termite species do not build a nest at all and instead found colonies inside the nests of other termites. Since these so-called inquilines do not need to be in direct contact with the host population, the two colonies usually live in separate parts of the nest. Adaptations of both the inquiline and its host are likely to occur to maintain the spatial exclusion and reduce the costs of potential conflicts. Among them, mutual avoidance, based on chemical cues, is expected. We investigated chemical aspects of cohabitation between Constrictotermes cavifrons (Nasutitermitinae) and its obligatory inquiline Inquilinitermes inquilinus (Termitinae). Inquiline soldiers produce in their frontal glands a blend of wax esters, consisting of the C 12 alcohols (3Z)-dodec enol, (3Z,6Z)-dodecadienol, and dodecanol, esterified with different fatty acids. The C 12 alcohols appear to be cleaved gradually from the wax esters, and they occur in the frontal gland, in soldier headspace, and in the walls of the inquiline part of the nest. Electrophysiological experiments revealed that (3Z)-dodecenol and (3Z,6Z)-dodecadienol are perceived by workers of both species. Bioassays indicated that inquiline soldier heads, as well as the two synthetic compounds, are attractive to conspecific workers and elicit an arresting behavior, while host soldiers and workers avoid these chemicals at biologically relevant amounts. These observations support the hypothesis that chemically mediated spatial separation of the host and the inquiline is an element of a conflict-avoidance strategy in these species.

Chemical separation of Mo and W from terrestrial and extraterrestrial samples via anion exchange chromatography.

PubMed

Nagai, Yuichiro; Yokoyama, Tetsuya

2014-05-20

A new two-stage chemical separation method was established using an anion exchange resin, Eichrom 1 × 8, to separate Mo and W from four natural rock samples. First, the distribution coefficients of nine elements (Ti, Fe, Zn, Zr, Nb, Mo, Hf, Ta, and W) under various chemical conditions were determined using HCl, HNO3, and HF. On the basis of the obtained distribution coefficients, a new technique for the two-stage chemical separation of Mo and W, along with the group separation of Ti-Zr-Hf, was developed as follows: 0.4 M HCl-0.5 M HF (major elements), 9 M HCl-0.05 M HF (Ti-Zr-Hf), 9 M HCl-1 M HF (W), and 6 M HNO3-3 M HF (Mo). After the chemical procedure, Nb remaining in the W fraction was separated using 9 M HCl-3 M HF. On the other hand, Nb and Zn remaining in the Mo fraction were removed using 2 M HF and 6 M HCl-0.1 M HF. The performance of this technique was evaluated by separating these elements from two terrestrial and two extraterrestrial samples. The recovery yields for Mo, W, Zr, and Hf were nearly 100% for all of the examined samples. The total contents of the Zr, Hf, W, and Mo in the blanks used for the chemical separation procedure were 582, 9, 29, and 396 pg, respectively. Therefore, our new separation technique can be widely used in various fields of geochemistry, cosmochemistry, and environmental sciences and particularly for multi-isotope analysis of these elements from a single sample with significant internal isotope heterogeneities.

Hydrogels for engineering: normalization of swelling due to arbitrary stimulus

NASA Astrophysics Data System (ADS)

Ehrenhofer, Adrian; Wallmersperger, Thomas

2017-04-01

In engineering, materials are chosen from databases: Engineers orient on specific parameters such as Young's modulus, yield stress or thermal expansion coefficients for a desired application. For hydrogels, the choice of materials is rather tedious since no generalized material parameters are currently available to quantify the swelling behavior. The normalization of swelling, which we present in the current work, allows an easy comparison of different hydrogel materials. Thus, for a specific application like a sensor or an actuator, an adequate material can be chosen. In the current work, we present the process of normalization and provide a course of action for the data analysis. Special challenges for hydrogels like hysteresis, conditional multi-sensitivity and anisotropic swelling are addressed. Then, the Temperature Expansion Model is shortly described and applied. Using the derived normalized swelling curves, a nonlinear expansion coefficient ß(F) is derived. The derived material behavior is used in an analytical model to predict the bending behavior of a beam made of thermo-responsive hydrogel material under an anisotropic temperature load. A bending behavior of the beam can be observed and the impact of other geometry and material parameters can be investigated. To overcome the limitations of the one-dimensional beam theory, the material behavior and geometry can be implemented in Finite Element analysis tools. Thus, novel applications for hydrogels in various fields can be envisioned, designed and tested. This can lead to a wider use of smart materials in sensor or actuator devices even by engineers without chemical background.

Pioneer plant species contributing to phytoestabilization of contaminated soils in mine areas

NASA Astrophysics Data System (ADS)

João Batista, Maria; Gonzalez-Fernandez, Oscar; Abreu, Maria Manuela; Carvalho, Luisa; Queralt, Ignasi

2013-04-01

Young and mature leaves from several plant species of the genus Cistus L. (C. crispus, C. ladanifer, C. monspeliensis, C. salviifolius), Erica australis L., and Lavandula sampaioana (Rozeira) Rivas Mart., T.E. Díaz& Fern. Gonz., as well as soils where plants grew, were sampled in various areas of São Domingos abandoned mine. The São Domingos mine, dating from pre-Roman times, is 60 km SE of Beja, Southeast Portugal. This mine belongs to the world class metallogenetic province of the Iberian Pyrite Belt. Sampling occurred throughout spring and winter to better understand plant behaviour and natural attenuation of contaminated soils. Multiple Correspondence Analysis (MCA) was used to synthesize the information and group characteristics that could justify different chemical concentrations. Soils are extremely acid (pH between 3.4 and 5.2) and present a wide range of Corganic concentrations (10.2-109 g/kg). Total nitrogen and extractable phosphorus concentrations are low to very low, but extractable potassium show medium to high concentrations. Chemical elements concentrations, analysed for total fraction, were great in soils, especially arsenic and lead that can attain 7.6 g/kg and 17.2 g/kg, respectively. However, only a small percentage (in general < 1%) of the total concentration of the chemical elements were water soluble (extracted by DIN 38414-S4 method) or extracted with the DTPA or ammonium acetate aqueous solutions. Cistus plants showed different behaviour on the trace-elements uptake and translocation. Winter and spring variations in most chemical elements concentrations in the plants leaves are not significantly different, except for arsenic, probably because plants were not exposed to important dry conditions during the sampling seasons. Nevertheless, MCA of the individuals makes a clear distinction between winter and spring leaves. Generally, mature leaves have higher concentrations of arsenic, copper, iron, lead, manganese and zinc than younger ones. However, in this study, sulfur concentrations show an opposite behaviour. Soil total and available fraction concentrations of the chemical elements have similar behaviour between sites. Chemical elements concentrations in plant leaves are independent of the same elements concentrations in soils where plants were developed. The obtained results showed the difficulty to understand the soil-plant system in heterogeneous materials such as mining sites. Other parameters such as plant physiology are responsible for the different uptake in the same species, contributing to the uncertainty of the remediation strategies. The studied native plants are well adapted to soils or spoils with different characteristics and high content of hazardous chemical elements. These species are adequate for stabilization strategies of a great variety of substrata. To improve and optimize remediation programs for mine areas in the Mediterranean region it is important to use several pioneer plants at the same time. This can contribute to reduce the costs of remediation with less environmental impact.

Chemical oscillators in structured media.

PubMed

Epstein, Irving R; Vanag, Vladimir K; Balazs, Anna C; Kuksenok, Olga; Dayal, Pratyush; Bhattacharya, Amitabh

2012-12-18

Evolution is a characteristic feature of living systems, and many fundamental processes in life, including the cell cycle, take place in a periodic fashion. From a chemistry perspective, these repeating phenomena suggest the question of whether reactions in which concentrations oscillate could provide a basis and/or useful models for the behavior of organisms, and perhaps even their ability to evolve. In this Account, we examine several aspects of the behavior of the prototype oscillating chemical reaction, the Belousov-Zhabotinsky (BZ) system, carried out in microemulsions, arrays of micrometer-sized aqueous droplets suspended in oil, or hydrogels. Each of these environments contains elements of the compartmentalization that likely played a role in the development of the first living cells, and within them we observe behaviors not found in the BZ reaction in simple aqueous solution. Several of these phenomena resemble traits displayed by living organisms. For example, the nanodroplets in a BZ microemulsion "communicate" with each other through a phenomenon analogous to quorum sensing in bacteria to produce a remarkable variety of patterns and waves on length scales 10(5) times the size of a single droplet. A photosensitive version can "remember" an imposed image. Larger, micrometer-sized droplets exhibit similarly rich behavior and allow for the observation and control of individual droplets. These droplets offer promise for building arrays capable of computation by varying the strength and sign of the coupling between drops. Gels that incorporate a BZ catalyst and are immersed in a solution containing the BZ reactants change their shape and volume in oscillations that follow the variation in the redox state of the catalyst. Using this phenomenon, we can construct phototactic gel "worms" or segments of gel that attract one another. Whether such systems will provide more realistic caricatures of life, and whether they can serve as useful materials will largely depend on the successful integration of various properties, including communication, motion, and memory, which we observed in separate experiments. Theoretical approaches that couple reaction and diffusion processes to mechanical and other material properties are likely to play a key role in this integration, and we describe one such approach. The evolution of systems of coupled chemical oscillators presents another challenge to the development of these systems, but one that we expect to be solved.

Periodic, Quasi-periodic and Chaotic Dynamics in Simple Gene Elements with Time Delays

PubMed Central

Suzuki, Yoko; Lu, Mingyang; Ben-Jacob, Eshel; Onuchic, José N.

2016-01-01

Regulatory gene circuit motifs play crucial roles in performing and maintaining vital cellular functions. Frequently, theoretical studies of gene circuits focus on steady-state behaviors and do not include time delays. In this study, the inclusion of time delays is shown to entirely change the time-dependent dynamics for even the simplest possible circuits with one and two gene elements with self and cross regulations. These elements can give rise to rich behaviors including periodic, quasi-periodic, weak chaotic, strong chaotic and intermittent dynamics. We introduce a special power-spectrum-based method to characterize and discriminate these dynamical modes quantitatively. Our simulation results suggest that, while a single negative feedback loop of either one- or two-gene element can only have periodic dynamics, the elements with two positive/negative feedback loops are the minimalist elements to have chaotic dynamics. These elements typically have one negative feedback loop that generates oscillations, and another unit that allows frequent switches among multiple steady states or between oscillatory and non-oscillatory dynamics. Possible dynamical features of several simple one- and two-gene elements are presented in details. Discussion is presented for possible roles of the chaotic behavior in the robustness of cellular functions and diseases, for example, in the context of cancer. PMID:26876008

Periodic, Quasi-periodic and Chaotic Dynamics in Simple Gene Elements with Time Delays

NASA Astrophysics Data System (ADS)

Suzuki, Yoko; Lu, Mingyang; Ben-Jacob, Eshel; Onuchic, José N.

2016-02-01

Regulatory gene circuit motifs play crucial roles in performing and maintaining vital cellular functions. Frequently, theoretical studies of gene circuits focus on steady-state behaviors and do not include time delays. In this study, the inclusion of time delays is shown to entirely change the time-dependent dynamics for even the simplest possible circuits with one and two gene elements with self and cross regulations. These elements can give rise to rich behaviors including periodic, quasi-periodic, weak chaotic, strong chaotic and intermittent dynamics. We introduce a special power-spectrum-based method to characterize and discriminate these dynamical modes quantitatively. Our simulation results suggest that, while a single negative feedback loop of either one- or two-gene element can only have periodic dynamics, the elements with two positive/negative feedback loops are the minimalist elements to have chaotic dynamics. These elements typically have one negative feedback loop that generates oscillations, and another unit that allows frequent switches among multiple steady states or between oscillatory and non-oscillatory dynamics. Possible dynamical features of several simple one- and two-gene elements are presented in details. Discussion is presented for possible roles of the chaotic behavior in the robustness of cellular functions and diseases, for example, in the context of cancer.

Sources of PM10 Air Pollution in Rural Area in the Vicinity of a Highway In Žilina Selfgoverning Region, Slovakia

NASA Astrophysics Data System (ADS)

Jandačka, Dušan

2015-05-01

Particulate matter results as an aftermath of numerous distinctive processes in the atmosphere and they become a part of everyday life. Their harmful effect and impact on the ambient environment is determined predominantly by the presence of various chemical substances and elements. The chemical composition of these particles (organic and elemental carbon, mineral dust, sea aerosols, secondary particles, especially sulphates and nitrates, heavy metals and further elements) is mainly impacted on by their origin, whereas the primary source of the particulate matter is determined and specified by the profile of chemical elements and substances. Particulate Matter (PM) may originate in various natural resources or anthropogenic sources. Among the natural sources sea salt is to be counted on, dust of the earth crust, pollen and volcanic ashes. Anthropogenic sources do include, predominantly, burning fossil fuels in the fossil-fuel power plants, local heating of households, burning liquefied fossil fuels in the combustion engines of vehicles, noncombustion related emissions as a result of vehicular traffic, resuspension of the road-traffic-related dust.

Effects of surgical and chemical sterilization on the behavior of free-roaming male dogs in Puerto Natales, Chile.

PubMed

Garde, E; Pérez, G E; Vanderstichel, R; Dalla Villa, P F; Serpell, J A

2016-01-01

Population management of free-roaming domestic dogs (Canis lupus familiaris) is of interest due to the threat these animals pose to people, other animals and the environment. Current sterilization procedures for male dogs include surgical and chemical methods. However, little is known about how these procedures affect their behavior. The primary objective of this study was to investigate changes in selected behaviors following chemical and surgical sterilization in a male free-roaming dog (FRD) population in southern Chile. We also examined the association between serum testosterone levels and behaviors thought to be influenced by circulating androgens. A total of 174 dogs were randomly assigned to either a surgical or chemical sterilization group, or a control group. At the onset of the intervention period, 119 dogs remained and 102 dogs successfully completed the study. Each dog was monitored pre- and post-intervention using video recordings, GPS collars, and blood samples for the measurement of testosterone. Analysis of behavior revealed that surgically castrated dogs showed no reduction of sexual activity or aggression when compared to their pre-intervention behavior. Chemically sterilized dogs showed a statistically significant increase in dog-directed aggression, but no change in sexual activity. There was no change in home range size in any groups between the pre- and post-intervention measurement. We found no consistent association between levels of serum testosterone concentration and behavioral changes in any of the groups. This study presents the first detailed behavioral observations following surgical and chemical sterilization in male FRDs. The information generated is highly relevant to communities struggling with the control of FRDs. Complementary studies to further our understanding of the effects of male sterilization on the behavioral and reproductive dynamics of FRD populations are needed. Copyright © 2015 Elsevier B.V. All rights reserved.

Geochemistry and stratigraphic correlation of basalt lavas beneath the Idaho Chemical Processing Plant, Idaho National Engineering Laboratory

USGS Publications Warehouse

Reed, M.F.; Bartholomay, R.C.; Hughes, S.S.

1997-01-01

Thirty-nine samples of basaltic core were collected from wells 121 and 123, located approximately 1.8 km apart north and south of the Idaho Chemical Processing Plant at the Idaho National Engineering Laboratory. Samples were collected from depths ranging from 15 to 221 m below land surface for the purpose of establishing stratigraphic correlations between these two wells. Elemental analyses indicate that the basalts consist of three principal chemical types. Two of these types are each represented by a single basalt flow in each well. The third chemical type is represented by many basalt flows and includes a broad range of chemical compositions that is distinguished from the other two types. Basalt flows within the third type were identified by hierarchical K-cluster analysis of 14 representative elements: Fe, Ca, K, Na, Sc, Co, La, Ce, Sm, Eu, Yb, Hf, Ta, and Th. Cluster analyses indicate correlations of basalt flows between wells 121 and 123 at depths of approximately 38-40 m, 125-128 m, 131-137 m, 149-158 m, and 183-198 m. Probable correlations also are indicated for at least seven other depth intervals. Basalt flows in several depth intervals do not correlate on the basis of chemical compositions, thus reflecting possible flow margins in the sequence between the wells. Multi-element chemical data provide a useful method for determining stratigraphic correlations of basalt in the upper 1-2 km of the eastern Snake River Plain.

A simple and general method for solving detailed chemical evolution with delayed production of iron and other chemical elements

NASA Astrophysics Data System (ADS)

Vincenzo, F.; Matteucci, F.; Spitoni, E.

2017-04-01

We present a theoretical method for solving the chemical evolution of galaxies by assuming an instantaneous recycling approximation for chemical elements restored by massive stars and the delay time distribution formalism for delayed chemical enrichment by Type Ia Supernovae. The galaxy gas mass assembly history, together with the assumed stellar yields and initial mass function, represents the starting point of this method. We derive a simple and general equation, which closely relates the Laplace transforms of the galaxy gas accretion history and star formation history, which can be used to simplify the problem of retrieving these quantities in the galaxy evolution models assuming a linear Schmidt-Kennicutt law. We find that - once the galaxy star formation history has been reconstructed from our assumptions - the differential equation for the evolution of the chemical element X can be suitably solved with classical methods. We apply our model to reproduce the [O/Fe] and [Si/Fe] versus [Fe/H] chemical abundance patterns as observed at the solar neighbourhood by assuming a decaying exponential infall rate of gas and different delay time distributions for Type Ia Supernovae; we also explore the effect of assuming a non-linear Schmidt-Kennicutt law, with the index of the power law being k = 1.4. Although approximate, we conclude that our model with the single-degenerate scenario for Type Ia Supernovae provides the best agreement with the observed set of data. Our method can be used by other complementary galaxy stellar population synthesis models to predict also the chemical evolution of galaxies.

Prospecting for hyperaccumulators of trace elements: a review.

PubMed

Krzciuk, Karina; Gałuszka, Agnieszka

2015-01-01

Specific plant species that can take up and accumulate abnormally high concentrations of elements in their aboveground tissues are referred to as "hyperaccumulators". The use of this term is justified in the case of enormous element-binding capacity of plants growing in their natural habitats and showing no toxicity symptoms. An increasing interest in the study of hyperaccumulators results from their potential applications in environmental biotechnology (phytoremediation, phytomining) and their emerging role in nanotechnology. The highest number of plant species with confirmed hyperaccumulative properties has been reported for hyperaccumulators of nickel, cadmium, zinc, manganese, arsenic and selenium. More limited data exist for plants accumulating other elements, including common pollutants (chromium, lead and boron) or elements of commercial value, such as copper, gold and rare earth elements. Different approaches have been used for the study of hyperaccumulators - geobotanical, chemical, biochemical and genetic. The chemical approach is the most important in screening for new hyperaccumulators. This article presents and critically reviews current trends in new hyperaccumulator research, emphasizing analytical methodology that is applied in identification of new hyperaccumulators of trace elements and its future perspectives.

The Metals in the Biological Periodic System of the Elements: Concepts and Conjectures

PubMed Central

Maret, Wolfgang

2016-01-01

A significant number of chemical elements are either essential for life with known functions, or present in organisms with poorly defined functional outcomes. We do not know all the essential elements with certainty and we know even less about the functions of apparently non-essential elements. In this article, I discuss a basis for a biological periodic system of the elements and that biochemistry should include the elements that are traditionally part of inorganic chemistry and not only those that are in the purview of organic chemistry. A biological periodic system of the elements needs to specify what “essential” means and to which biological species it refers. It represents a snapshot of our present knowledge and is expected to undergo further modifications in the future. An integrated approach of biometal sciences called metallomics is required to understand the interactions of metal ions, the biological functions that their chemical structures acquire in the biological system, and how their usage is fine-tuned in biological species and in populations of species with genetic variations (the variome). PMID:26742035

Mobility of plume-derived volcanogenic elements in meteoric water at Nyiragongo volcano (Congo) inferred from the chemical composition of single rainfall events

NASA Astrophysics Data System (ADS)

Liotta, Marcello; Shamavu, Patient; Scaglione, Sarah; D'Alessandro, Walter; Bobrowski, Nicole; Bruno Giuffrida, Giovanni; Tedesco, Dario; Calabrese, Sergio

2017-11-01

The chemical composition of single rainfall events was investigated at Nyiragongo volcano (Democratic Republic of Congo) with the aim of determining the relative contributions of plume-derived elements. The different locations of the sampling sites allowed both plume-affected samples (hereafter referred to as ;fumigated samples;) and samples representative of the local background to be collected. The chemical composition of the local background reflects the peculiar geographic features of the area, being influenced by biomass burning, geogenic dust, and biological activity. Conversely, fumigated samples contain large amounts of volcanogenic elements that can be clearly distinguished from the local background. These elements are released into the atmosphere from the persistently boiling lava lake of the Nyiragongo crater and from the neonate lava lake of Nyamulagira. These emissions result in a volcanic plume that includes solid particles, acidic droplets, and gaseous species. The chemical signature of the volcanic emissions appears in falling raindrops as they interact with the plume. HCl and HBr readily dissolve in water, and so their ratio in rain samples reflects that of the volcanic plume. The transport of HF is mediated by the large amount of silicate particles generated at the magma-air interface. SO2 is partially converted into SO42- that dissolves in water. The refractory elements dissolved in rain samples derive from the dissolution of silicate particles, and most of them (Al, Mg, Ca, and Sr) are present at exactly the same molar ratios as in the rocks. In contrast, elements such as Na, K, Rb, Cu, and Pb are enriched relative to the whole-rock composition, suggesting that they are volatilized during magma degassing. After correcting for the dissolution of silicate particles, we can define that the volatility of the elements decreases in the following order: Pb ≫ Rb > K > Na. This finding, which is the first for a volcanic plume, is consistent with previous measurements in high-temperature fumaroles at other volcanic areas.

Analysis of Degree of Similarity among Crude Oils, the Upper and the Lower Crust, Organic Matter, Clays, and Different Caustobioliths by the Content of Their Main and Trace Elements

NASA Astrophysics Data System (ADS)

Rodkin, Mikhail; Punanova, Svetlana

2016-04-01

The goal of this research was to estimate, based on the content of Trace Elements, the level of contribution of the lower and the upper crust as well as the organic matter into ontogenesis of hydrocarbons. The analysis of degree of similarity of the main and trace element (TE) content among the upper and lower continental crust, clays, organic matter, and different caustobioliths (oil, coal, oil-and-black shales) is performed by calculating coefficients of correlation of logarithms of concentrations of a large number of different chemical elements. Different oils from a number of oil bearing provinces in Russia and from the volcanic caldera Uzon (Kamchatka, Russia) were examined. It has been shown that the content of main elements and TEs of coals and oil-and-black shales is better correlated with the chemical composition of the upper crust, while the TE content of oils correlates better with the composition of the lower continental crust. The TE content of oils correlates with the chemical content of living organisms but the correlation in the most cases is weaker than the one with the lower crust. The results of the examination of different samples from the same oil-bearing province were found to be similar. The mean results for different oil-bearing provinces can vary considerably. The results of the examination of young oil from the Uzon volcanic caldera were found to be rather specific and different from the other oils. We also suggest a set of a small number of "characteristic" elements (Cs, Rb, K, U, V, Cr and Ni), which allows to compare the degree of similarity between an oil sample and upper or lower continental crust using only a few chemical elements. Some interpretation of the results is presented.

Stratospheric Sampling and In Situ Atmospheric Chemical Element Analysis During Meteor Showers: A Resource Study

NASA Technical Reports Server (NTRS)

Noever, David A.

2000-01-01

Resources studies for asteroidal mining evaluation have depended historically on remote sensing analysis for chemical elements. During the November 1998 Leonids meteor shower, a stratospheric balloon and various low-density capture media were used to sample fragments from Comet Tempel-Tuttle debris during a peak Earth crossing. The analysis not only demonstrates how potential sampling strategies may improve the projections for metals or rare elements in astromining, but also benchmarks materials during low temperature (-60 F), high dessication environments as seen during atmospheric exposure. The results indicate high aluminum, magnesium and iron content for various sampled particles recovered, but generalization to the sporadic meteors expected from asteroidal sources will require future improvements in larger sampling volumes before a broad-use strategy for chemical analysis can be described. A repeat of the experimental procedure is planned for the November 1999 Leonids' shower, and various improvements for atmospheric sampling will be discussed.

Chemical Analyses of Pre-Holocene Rocks from Medicine Lake Volcano and Vicinity, Northern California

USGS Publications Warehouse

Donnelly-Nolan, Julie M.

2008-01-01

Chemical analyses are presented in an accompanying table (Table 1) for more than 600 pre-Holocene rocks collected at and near Medicine Lake Volcano, northern California. The data include major-element X-ray fluorescence (XRF) analyses for all of the rocks plus XRF trace element data for most samples, and instrumental neutron activation analysis (INAA) trace element data for many samples. In addition, a limited number of analyses of Na2O and K2O by flame photometry (FP) are included as well assome wet chemical analyses of FeO, H2O+/-, and CO2. Latitude and longitude location information is provided for all samples. This data set is intended to accompany the geologic map of Medicine Lake Volcano (Donnelly-Nolan, in press); map unit designations are given for each sample collected from the map area.

The ability of the Coincidence Doppler Broadening Spectroscopy to characterize polymers containing different chemical elements

NASA Astrophysics Data System (ADS)

Yang, J.; Zhang, T.; Han, L. A.; Cao, X. Z.; Yu, R. S.; Wang, B. Y.

2017-04-01

Hydrocarbon polymers, O-containing, F-containing and Cl-containing polymers are comprehensively studied by Coincidence Doppler Broadening Spectroscopy (CDBS). It is shown that for polymers with different chemical structure, CDBS results can effectively distinguish polar groups C dbnd O, Csbnd Cl, and Csbnd F. For polymers with similar chemical structure, the intensity of the element-specific peak in the CDBS ratio curve is dependent not only on the fraction of free positrons, but also on the content of characteristic atom in polymer repeated unit, and the polarity of the polymer molecule. For polymers containing several different polar groups, such as PCTFE (Csbnd F & Csbnd Cl) and PFA (Csbnd F & C dbnd O), whether the element-specific peak appears or not depends on the amount of the polar groups and its positron capture ability. This work may provide insights into potential applications of CDBS for studying complex polymer systems.

Low temperature chemical processing of graphite-clad nuclear fuels

DOEpatents

Pierce, Robert A.

2017-10-17

A reduced-temperature method for treatment of a fuel element is described. The method includes molten salt treatment of a fuel element with a nitrate salt. The nitrate salt can oxidize the outer graphite matrix of a fuel element. The method can also include reduced temperature degradation of the carbide layer of a fuel element and low temperature solubilization of the fuel in a kernel of a fuel element.

Characteristics and environmental aspects of slag: a review

USGS Publications Warehouse

Piatak, Nadine M.; Parsons, Michael B.; Seal, Robert R.

2015-01-01

The composition of ferrous slag is dominated by Ca and Si. Steel slag may contain significant Fe, whereas Mg and Al may be significant in Fe slag. Calcium-rich olivine-group silicates, melilite-group silicates that contain Al or Mg, Ca-rich glass, and oxides are the most commonly reported major phases in ferrous slag. Calcite and trace amounts of a variety of sulfides, intermetallic compounds, and pure metals are typically also present. The composition of non-ferrous slag, most commonly from base-metal production, is dominated by Fe and Si with significant but lesser amounts of Al and Ca. Silicates in the olivine, pyroxene, and melilite groups, as well as glass, spinels, and SiO2 (i.e., quartz and other polymorphs) are commonly found in non-ferrous slag. Sulfides and intermetallic compounds are less abundant than the silicates and oxides. The concentrations of some elements exceed generic USEPA soil screening levels for human contact based on multiple exposure pathways; these elements include Al, Cr, Cu, Fe, Mn, Pb, and Zn based on bulk chemical composition. Each slag type usually contains a specific suite of elements that may be of environmental concern. In general, non-ferrous slag may have a higher potential to negatively impact the environment compared to ferrous slag, and is thus a less attractive material for reuse, based on trace element chemistry, principally for base metals. However, the amount of elements released into the environment is not always consistent with bulk chemical composition. Many types of leaching tests have been used to help predict slag’s long-term environmental behavior. Overall, ferrous slags produce an alkaline leachate due to the dissolution of Ca oxides and silicates derived from compounds originally added as fluxing agents, such as lime. Ferrous slag leachate is commonly less metal-rich than leachate from non-ferrous slag generated during base metal extraction; the latter leachate may even be acidic due to the oxidation of sulfides. Because of its characteristics, ferrous slag is commonly used for construction and environmental applications, whereas both non-ferrous and ferrous slag may be reprocessed for secondary metal recovery. Both types of slag have been a source of some environmental contamination. Research into the environmental aspects of slag will continue to be an important topic whether the goal is its reuse, recycling, or remediation.

Mobility and fluxes of major, minor and trace metals during basalt weathering and groundwater transport at Mt. Etna volcano (Sicily)

NASA Astrophysics Data System (ADS)

Aiuppa, Alessandro; Allard, Patrick; D'Alessandro, Walter; Michel, Agnes; Parello, Francesco; Treuil, Michel; Valenza, Mariano

2000-06-01

The concentrations and fluxes of major, minor and trace metals were determined in 53 samples of groundwaters from around Mt Etna, in order to evaluate the conditions and extent of alkali basalt weathering by waters enriched in magma-derived CO 2 and the contribution of aqueous transport to the overall metal discharge of the volcano. We show that gaseous input of magmatic volatile metals into the Etnean aquifer is small or negligible, being limited by cooling of the rising fluids. Basalt leaching by weakly acidic, CO 2-charged water is the overwhelming source of metals and appears to be more extensive in two sectors of the S-SW (Paternò) and E (Zafferana) volcano flanks, where out flowing groundwaters are the richest in metals and bicarbonate of magmatic origin. Thermodynamic modeling of the results allows to evaluate the relative mobility and chemical speciation of various elements during their partitioning between solid and liquid phases through the weathering process. The facts that rock-forming minerals and groundmass dissolve at different rates and secondary minerals are formed are taken into account. At Mt. Etna, poorly mobile elements (Al, Th, Fe) are preferentially retained in the solid residue of weathering, while alkalis, alkaline earth and oxo-anion-forming elements (As, Se, Sb, Mo) are more mobile and released to the aqueous system. Transition metals display an intermediate behavior and are strongly dependent on either the redox conditions (Mn, Cr, V) or solid surface-related processes (V, Zn, Cu). The fluxes of metals discharged by the volcanic aquifer of Etna range from 7.0 × 10 -3 t/a (Th) to 7.3 × 10 4 t/a (Na). They are comparable in magnitude to the summit crater plume emissions for a series of elements (Na, K, Ca, Mg, U, V, Li) with lithophile affinity, but are minor for volatile elements. Basalt weathering at Mt Etna also consumes about 2.1 × 10 5 t/a of magma-derived carbon dioxide, equivalent to ca. 7% of contemporaneous crater plume emissions. The considerable transport of some metals in Etna's aquifer reflects a particularly high chemical erosion rate, evaluated at 2.3∗10 5 t/a, enhanced by the initial acidity of magmatic CO 2-rich groundwater.

A versatile transfection assay system to evaluate the biological effects of diverse industrial chemicals.

PubMed

Koizumi, Shinji; Ohno, Shotaro; Otsuka, Fuminori

2012-01-01

Gene expression processes are now recognized as important targets of the toxic effects exerted by industrial chemicals. The transient transfection assay is a powerful tool to evaluate such effects. Thus, we developed a versatile assay system by constructing a basic reporter plasmid in which the regulatory DNA sequence to be studied can easily be substituted. To verify the performance of this system, reporter plasmids carrying any of the three distinct regulatory sequences, estrogen responsive element (ERE), glucocorticoid responsive element (GRE) and xenobiotic responsive element (XRE) were constructed. After transfection of human cells, these plasmids successfully expressed the relevant reporter genes in response to specific inducers, β-estradiol, dexamethasone and 3-methylcholanthrene, respectively. Several industrial chemicals were assayed using these reporter plasmids, and the ability of p-dimethylaminoazobenzene to elevate GRE- and XRE-mediated transcription was detected. α-Naphthylamine and o-tolidine were also observed to increase the XRE-mediated response. The transfection assay system established here will be useful to evaluate the effects of a wide variety of industrial chemicals.

Chemical Abundance Analysis of Moving Group W11450 (Latham 1)

NASA Astrophysics Data System (ADS)

O'Connell, Julia E.; Martens, Kylee; Frinchaboy, Peter M.

2016-12-01

We present elemental abundances for all seven stars in Moving Group W11450 (Latham 1) to determine if they may be chemically related. These stars appear to be both spatially and kinematically related, but no spectroscopic abundance analysis exists in literature. Abundances for eight elements were derived via equivalent width analyses of high-resolution (R ˜ 60,000), high-signal-to-noise ratio (< {{S}}/{{N}}> ˜ 100) spectra obtained with the Otto Struve 2.1 m telescope and the Sandiford Echelle Spectrograph at McDonald Observatory. The large star-to-star scatter in metallicity, -0.55 ≤ [Fe/H] ≤slant 0.06 dex (σ = 0.25), implies these stars were not produced from the same chemically homogeneous molecular cloud, and are therefore not part of a remnant or open cluster as previously proposed. Prior to this analysis, it was suggested that two stars in the group, W11449 and W11450, are possible wide binaries. The candidate wide binary pair show similar chemical abundance patterns with not only iron but with other elements analyzed in this study, suggesting the proposed connection between these two stars may be real.

Lubricant effects on bearing life

NASA Technical Reports Server (NTRS)

Zaretsky, Erwin V.

1986-01-01

Lubricant considerations for rolling-element bearings have within the last two decades taken on added importance in the design and operation of mechanical systems. The phenomenon which limits the useful life of bearings is rolling-element or surface pitting fatigue. The elastohydrodynamic (EHD) film thickness which separates the ball or roller surface from those of the raceways of the bearing directly affects bearing life. Chemical additives added to the lubricant can also significantly affect bearings life and reliability. The interaction of these physical and chemical effects is important to the design engineer and user of these systems. Design methods and lubricant selection for rolling-element bearings are presented and discussed.

Multiple heteroatom substitution to graphene nanoribbon

PubMed Central

Meyer, Ernst

2018-01-01

Substituting heteroatoms into nanostructured graphene elements, such as graphene nanoribbons, offers the possibility for atomic engineering of electronic properties. To characterize these substitutions, functionalized atomic force microscopy (AFM)—a tool to directly resolve chemical structures—is one of the most promising tools, yet the chemical analysis of heteroatoms has been rarely performed. We synthesized multiple heteroatom-substituted graphene nanoribbons and showed that AFM can directly resolve elemental differences and can be correlated to the van der Waals radii, as well as the modulated local electron density caused by the substitution. This elemental-sensitive measurement takes an important step in the analysis of functionalized two-dimensional carbon materials. PMID:29662955

Heaviest Nuclei: New Element with Atomic Number 117

ScienceCinema

Oganessian, Yuri

2018-01-24

One of the fundamental outcomes of the nuclear shell model is the prediction of the 'stability islands' in the domain of the hypothetical super heavy elements. The talk is devoted to the experimental verification of these predictions - the synthesis and study of both the decay and chemical properties of the super heavy elements. The discovery of a new chemical element with atomic number Z=117 is reported. The isotopes 293117 and 294117 were produced in fusion reactions between 48Ca and 249Bk. Decay chains involving 11 new nuclei were identified by means of the Dubna gas-filled recoil separator. The measured decay properties show a strong rise of stability for heavier isotopes with Z =111, validating the concept of the long sought island of enhanced stability for heaviest nuclei.

Emergy of the Global Biogeochemical Cycles of Biologically Active Elements

EPA Science Inventory

Accurate estimates of the emergy of elemental flows are needed to accurately evaluate the far field effects of anthropogenic wastes. The transformity and specific emergy of the elements and of their different chemical species is also needed to quantify the inputs to many producti...

Cosmic phylogeny: reconstructing the chemical history of the solar neighbourhood with an evolutionary tree

NASA Astrophysics Data System (ADS)

Jofré, Paula; Das, Payel; Bertranpetit, Jaume; Foley, Robert

2017-05-01

Using 17 chemical elements as a proxy for stellar DNA, we present a full phylogenetic study of stars in the solar neighbourhood. This entails applying a clustering technique that is widely used in molecular biology to construct an evolutionary tree from which three branches emerge. These are interpreted as stellar populations that separate in age and kinematics and can be thus attributed to the thin disc, the thick disc and an intermediate population of probable distinct origin. We further find six lone stars of intermediate age that could not be assigned to any population with enough statistical significance. Combining the ages of the stars with their position on the tree, we are able to quantify the mean rate of chemical enrichment of each of the populations, and thus show in a purely empirical way that the star formation rate in the thick disc is much higher than that in the thin disc. We are also able to estimate the relative contribution of dynamical processes such as radial migration and disc heating to the distribution of chemical elements in the solar neighbourhood. Our method offers an alternative approach to chemical tagging methods with the advantage of visualizing the behaviour of chemical elements in evolutionary trees. This offers a new way to search for 'common ancestors' that can reveal the origin of solar neighbourhood stars.

Dynamics of a discrete chain of bi-stable elements: A biomimetic shock absorbing mechanism

NASA Astrophysics Data System (ADS)

Cohen, T.; Givli, S.

2014-03-01

A biomimetic shock absorbing mechanism, inspired by the bi-stable elongation behavior of the giant protein titin, is examined. A bi-stable element, composed of three mass particles with monotonous interaction forces, is suggested to facilitate an internal degree of freedom of finite mass which contributes significantly to dissipation upon unlocking of an internal link. An essential feature of the suggested element is that it undergoes reversible rapture and therefore retrieves its initial configuration once unloaded. The quasistatic and dynamic behaviors are investigated showing similarity to the common tri-linear bi-stable response, with two steady phases separated by a spinodal region. The dynamic behavior of a chain of elements is also examined, for several loading scenarios, showing that the suggested mechanism serves as an efficient shock absorber in a sub-critical dampening environment, as compared with a simple mass on spring system. Propagation of shock waves and refraction waves in an element chain is observed and the effect of natural imperfections is considered.

New Fragment Separation Technology for Superheavy Element Research

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shaughnessy, D A; Moody, K J; Henderson, R A

2008-01-28

This project consisted of three major research areas: (1) development of a solid Pu ceramic target for the MASHA separator, (2) chemical separation of nuclear decay products, and (3) production of new isotopes and elements through nuclear reactions. There have been 16 publications as a result of this project, and this collection of papers summarizes our accomplishments in each of the three areas of research listed above. The MASHA (Mass Analyzer for Super-Heavy Atoms) separator is being constructed at the U400 Cyclotron at the Flerov Laboratory of Nuclear Reactions in Dubna, Russia. The purpose of the separator is to physicallymore » separate the products from nuclear reactions based on their isotopic masses rather than their decay characteristics. The separator was designed to have a separation between isotopic masses of {+-}0.25 amu, which would enable the mass of element 114 isotopes to be measured with outstanding resolution, thereby confirming their discovery. In order to increase the production rate of element 114 nuclides produced via the {sup 244}Pu+{sup 48}Ca reaction, a new target technology was required. Instead of a traditional thin actinide target, the MASHA separator required a thick, ceramic-based Pu target that was thick enough to increase element 114 production while still being porous enough to allow reaction products to migrate out of the target and travel through the separator to the detector array located at the back end. In collaboration with UNLV, we began work on development of the Pu target for MASHA. Using waste-form synthesis technology, we began by creating zirconia-based matrices that would form a ceramic with plutonium oxide. We used samarium oxide as a surrogate for Pu and created ceramics that had varying amounts of the starting materials in order to establish trends in material density and porosity. The results from this work are described in more detail in Refs. [1,4,10]. Unfortunately, work on MASHA was delayed in Russia because it was found that the efficiency of transporting products from the target chamber to the detector array was much too low for applications in heavy element experiments where production rates are on the order of one atom per day or less. Work continues on the MASHA separator, and once the efficiency has been improved, we plan to continue our work on the Pu target for future element 114 experiments. Due to the delays of the MASHA separator, work on establishing the identity of heavy element species produced through nuclear reactions focused instead on chemical separations. In particular, element 115 decays through a series of alpha decays, terminating with an element 105 isotope with a long half-life ({approx} 1 day). By chemically separating the element 105 daughter and observing its subsequent fission decay, the identity of the original parent nucleus can be established through the genetic correlation of the initial series of alpha decays. Chemical separations of element 105 were developed in Switzerland, Russia, and at LLNL. Over the course of two experiments, reaction products from the {sup 243}Am+{sup 48}Ca reaction were collected in a copper block and subsequently processed for chemical separation of the Group Five elements [8,9,13,15]. The Group Five elements were initially separated from the Group Four species, and then the samples were sub-divided into tantalum and niobium fractions. All of the fission events were observed in the tantalum fractions, which implied that element 105 behaved more like tantalum under the chemical conditions of these experiments. These experiments were very successful, and not only demonstrated that chemical separation could be performed on single atoms of interest, but also lent proof to the identity of the parent nucleus as element 115. Subsequent analysis of the alpha spectra taken during the experiment further prove that the fission events observed during the two experiments came from element 105 as the decay daughter of element 115 and could not attributed to interference from other background species [16]. The final aspect of this project was the production of new isotopes and elements. All of the experiments were performed in Dubna at the U400 Cyclotron and the results are described in more detail in Refs. [2,3,5-8,11,12,14]. The first experiments were designed to establish the decay properties of isotopes of elements 112, 114, and 116 [5]. Because these isotopic signatures were established through these initial experiments, the discovery of element 118 [11] was possible, since the 118 nuclides decayed into these previously studied isotopes. This was the first successful report of the discovery of element 118, which was reported by the media to a large extent. The last experiment that was performed for this project was the production and detection of a new isotope of element 113 [14].« less

Surface chemical composition of human maxillary first premolar as assessed by X-ray photoelectron spectroscopy (XPS)

NASA Astrophysics Data System (ADS)

Lou, Leo; Nelson, Alan E.; Heo, Giseon; Major, Paul W.

2008-08-01

The surface chemical composition of dental enamel has been postulated as a contributing factor in the variation of bond strength of brackets bonded to teeth, and hence, the probability of bracket failure during orthodontic treatment. This study systematically investigated the chemical composition of 98 bonding surfaces of human maxillary premolars using X-ray photoelectron spectroscopy (XPS) to ascertain compositional differences between right and left first premolars. The major elements detected in all samples were calcium, phosphorus, oxygen, nitrogen and carbon. Surface compositions were highly variable between samples and several elements were found to be highly correlated. No statistical significant difference in the chemical composition of the maxillary right and left first premolars was found ( p > 0.05). Knowledge of the chemical composition of enamel surfaces will facilitate future studies that relate this information to the variations in dental enamel bond strength.

Chemical signature of a migrating grain boundaries in polycrystalline olivine

NASA Astrophysics Data System (ADS)

Boneh, Y.; Marquardt, K.; Skemer, P. A.

2017-12-01

Olivine is the most abundant phase and influences strongly the physical and chemical properties of the upper mantle. The structure and chemistry of olivine grain-boundaries is important to understand, as these interfaces provide a reservoir for incompatible elements and partial melt, and serve as a fast pathway for chemical diffusion. This project investigates the chemical characteristics of grain boundaries in an olivine-rich aggregate. The sample is composed of Fo50 olivine crystals with minor amounts of enstatite. It was previously deformed (Hansen et al., 2016) and then annealed (Boneh et al., 2017) to investigate the microstructural changes during recrystallization. This transient microstructure has a bimodal grain size distribution and includes grains that experienced abnormal grain-growth, (porphyroblasts) and highly strained grains with no significant recrystallization or growth (matrix). Using high-resolution transmission electron microscopy (HR-TEM) with energy dispersive X-ray (EDX) at the Bayerisches Geoinstitut (BGI), we characterized boundaries between pairs of porphyroblasts, pairs of matrix grains, and mixed boundaries between porphyroblast and matrix grains. It was found that the boundary between porphyroblasts is enriched in Al and Ca and depleted in Mg, in comparison to grain interiors. However, matrix-matrix boundaries show less chemical segregation of these elements. The relatively high level of chemical segregation to porphyroblast grain boundaries offers different possible interpretations: 1) During grain boundary migration incompatible elements are swept up by the migrating grain boundary. 2) Large angle grain boundaries provide a large density of energetically favorable storage sites for incompatible elements. 3) Diffusion along low angle grain boundaries is too slow to allow for fast chemical equilibration between the different grain boundaries. 4) Dislocations cores serve as an important transport media for impurities (i.e., Cottrell atmosphere). We will further discuss these different interpretations, their feasibility, and implications for the geochemistry of the mantle.

Reactivity and mobilization of permafrost-derived organic matter along the Lena River Delta - Laptev Sea transition

NASA Astrophysics Data System (ADS)

Koch, Boris P.; Dubinenkov, Ivan; Flerus, Ruth; Schmitt-Kopplin, Philippe; Kattner, Gerhard

2015-04-01

The impact of global warming on organic carbon budgets in permafrost systems are not well constrained. Changes in organic carbon fluxes caused by permafrost thaw depend on microbial activity, coastal erosion, mobilization of organic matter by increased porewater fluxes, and the inherent chemical stability of organic matter in permafrost soils. Here we aim at the identification and molecular characterization of active and inactive dissolved organic matter (DOM) components within the river-ocean transition. We studied four transects in the coastal Laptev Sea characterized by steep physico-chemical gradients. Molecular information on solid-phase extracted DOM was derived from ultrahigh resolution mass spectrometry. Changes of the chemical composition with salinity were used as a measure for DOM reactivity. Although changes of dissolved organic carbon (DOC) in the estuary suggested conservative mixing, only 27% of the identified molecular formulas behaved conservatively, 32% were moderately affected, and 41% were actively involved in estuarine processes. The molecular complexity in the DOM samples increased with growing marine influence and the average elemental composition (i.e. relative contribution of organic nitrogen and oxygen compounds) changed significantly with increasing salinity. These chemical changes were consistent with the results of a 20-day microbial incubation experiment, during which more than half of the permafrost-derived DOC was mineralized. We conclude that, although the DOC gradient in the estuary suggests conservative behavior, terrestrial DOM is substantially affected by estuarine processes which in turn also impact organic carbon budgets in the Lena Delta.

Surface conditions of Nitinol wires, tubing, and as-cast alloys. The effect of chemical etching, aging in boiling water, and heat treatment.

PubMed

Shabalovskaya, S A; Anderegg, J; Laab, F; Thiel, P A; Rondelli, G

2003-04-15

The surface conditions of Nitinol wires and tubing were evaluated with the use of X-ray photoelectron spectroscopy, high-resolution Auger spectroscopy, electron backscattering, and scanning-electron microscopy. Samples were studied in the as-received state as well as after chemical etching, aging in boiling water, and heat treatment, and compared to a mechanically polished 600-grit-finish Nitinol surface treated similarly. General regularities in surface behavior induced by the examined surface treatments are similar for wires, tubing, and studied as-cast alloy, though certain differences in surface Ni concentration were observed. Nitinol wires and tubing from various suppliers demonstrated great variability in Ni surface concentration (0.5-15 at.%) and Ti/Ni ratio (0.4-35). The wires in the as-received state, with the exception of those with a black oxide originating in the processing procedure, revealed nickel and titanium on the surface in both elemental and oxidized states, indicating a nonpassive surface. Shape-setting heat treatment at 500 degrees C for 15 min resulted in tremendous increase in the surface Ni concentration and complete Ni oxidation. Preliminary chemical etching and boiling in water successfully prevented surface enrichment in Ni, initially resulting from heat treatment. A stoichiometric uniformly amorphous TiO(2) oxide generated during chemical etching and aging in boiling water was reconstructed at 700 degrees C, revealing rutile structure. Copyright 2003 Wiley Periodicals, Inc.

In situ laser-induced breakdown spectroscopy measurements of chemical compositions in stainless steels during tungsten inert gas welding

NASA Astrophysics Data System (ADS)

Taparli, Ugur Alp; Jacobsen, Lars; Griesche, Axel; Michalik, Katarzyna; Mory, David; Kannengiesser, Thomas

2018-01-01

A laser-induced breakdown spectroscopy (LIBS) system was combined with a bead-on-plate Tungsten Inert Gas (TIG) welding process for the in situ measurement of chemical compositions in austenitic stainless steels during welding. Monitoring the weld pool's chemical composition allows governing the weld pool solidification behavior, and thus enables the reduction of susceptibility to weld defects. Conventional inspection methods for weld seams (e.g. ultrasonic inspection) cannot be performed during the welding process. The analysis system also allows in situ study of the correlation between the occurrence of weld defects and changes in the chemical composition in the weld pool or in the two-phase region where solid and liquid phase coexist. First experiments showed that both the shielding Ar gas and the welding arc plasma have a significant effect on the selected Cr II, Ni II and Mn II characteristic emissions, namely an artificial increase of intensity values via unspecific emission in the spectra. In situ investigations showed that this artificial intensity increase reached a maximum in presence of weld plume. Moreover, an explicit decay has been observed with the termination of the welding plume due to infrared radiation during sample cooling. Furthermore, LIBS can be used after welding to map element distribution. For austenitic stainless steels, Mn accumulations on both sides of the weld could be detected between the heat affected zone (HAZ) and the base material.

Water-soluble ions and trace elements in surface snow and their potential source regions across northeastern China

NASA Astrophysics Data System (ADS)

Wang, Xin; Pu, Wei; Zhang, Xueying; Ren, Yong; Huang, Jianping

2015-08-01

We collected 92 snow samples from 13 sites across northeastern China from January 7 to February 15, 2014. The surface snow samples were analyzed for the major water-soluble ions (SO42-, NO3-, F-, Cl-, Na+, K+, Ca2+, Mg2+, and NH4+) and trace element (Al, As, Mn, V, Cd, Cu, Pb, Zn, Fe, Cr, and Ni). The results indicated that the higher concentrations of NO3- and SO42- and the trace elements Zn, Pb, Cd, Ni, and Cu were likely attributable to enhanced local industrial emissions in East Asia especially in China. In addition, snow samples characterized by higher enrichment factors of trace elements (Cu, Cd, As, Zn, Pb) were indicative of an anthropogenic source. Emissions from fossil fuel combustion and biomass burning were likely important contributors to the chemical elements in seasonal snow with long-range transport. On the other hand, the large attribution of K+ appeared in the higher latitude demonstrated that biomass burning was a dominated factor of the chemical species in seasonal snow in the higher latitude of China than that in the lower latitude. Finally, an interannual comparison with the 2010 China snow survey also confirmed the source attributions of chemical speciation in seasonal snow in these regions.

Gas phase chemical studies of superheavy elements using the Dubna gas-filled recoil separator - Stopping range determination

NASA Astrophysics Data System (ADS)

Wittwer, D.; Abdullin, F. Sh.; Aksenov, N. V.; Albin, Yu. V.; Bozhikov, G. A.; Dmitriev, S. N.; Dressler, R.; Eichler, R.; Gäggeler, H. W.; Henderson, R. A.; Hübener, S.; Kenneally, J. M.; Lebedev, V. Ya.; Lobanov, Yu. V.; Moody, K. J.; Oganessian, Yu. Ts.; Petrushkin, O. V.; Polyakov, A. N.; Piguet, D.; Rasmussen, P.; Sagaidak, R. N.; Serov, A.; Shirokovsky, I. V.; Shaughnessy, D. A.; Shishkin, S. V.; Sukhov, A. M.; Stoyer, M. A.; Stoyer, N. J.; Tereshatov, E. E.; Tsyganov, Yu. S.; Utyonkov, V. K.; Vostokin, G. K.; Wegrzecki, M.; Wilk, P. A.

2010-01-01

Currently, gas phase chemistry experiments with heaviest elements are usually performed with the gas-jet technique with the disadvantage that all reaction products are collected in a gas-filled thermalisation chamber adjacent to the target. The incorporation of a physical preseparation device between target and collection chamber opens up the perspective to perform new chemical studies. But this approach requires detailed knowledge of the stopping force (STF) of the heaviest elements in various materials. Measurements of the energy loss of mercury (Hg), radon (Rn), and nobelium (No) in Mylar and argon (Ar) were performed at low kinetic energies of around (40-270) keV per nucleon. The experimentally obtained values were compared with STF calculations of the commonly used program for calculating stopping and ranges of ions in matter (SRIM). Using the obtained data points an extrapolation of the STF up to element 114, eka-lead, in the same stopping media was carried out. These estimations were applied to design and to perform a first chemical experiment with a superheavy element behind a physical preseparator using the nuclear fusion reaction 244Pu( 48Ca; 3n) 289114. One decay chain assigned to an atom of 285112, the α-decay product of 289114, was observed.

Re-187 Os-187 Isotopic and Highly Siderophile Element Systematics of Group IVB Irons

NASA Technical Reports Server (NTRS)

Honesto, J.; McDonough, W. F.; Walker, R. J.; McCoy, T. J.; Ash, R. D.

2005-01-01

Study of the magmatic iron meteorite groups permits constraints to be placed on the chemical and isotopic composition of parent bodies, and the timing of, and crystal-liquid fractionation processes involved in the crystallization of asteroidal cores. Here we examine Re-Os isotopic and trace elemental systematics of group IVB irons. Compared to most irons, the irons comprising this group are enriched in some of the most refractory siderophile elements, yet highly-depleted in most volatile siderophile elements. These characteristics have been attributed to processes such as high temperature condensation of precursor materials and oxidation in the parent body. Most recently it has been suggested that both processes may be involved in the chemical complexity of the group. Here, high precision isotopic and highly siderophile element (HSE) concentrations are used to further examine these possible origins, and the crystallization history of the group. In addition, we have begun to assess the possibility of relating certain ungrouped irons with major groups via multi-element, trace element modeling. In a companion abstract, the isotopic and trace element systematics of the ungrouped iron Tishomingo are compared with the IVB irons.

MODELING MULTICOMPONENT ORGANIC CHEMICAL TRANSPORT IN THREE-FLUID-PHASE POROUS MEDIA

EPA Science Inventory

A two dimensional finite-element model was developed to predict coupled transient flow and multicomponent transport of organic chemicals which can partition between NAPL, water, gas and solid phases in porous media under the assumption of local chemical equilibrium. as-phase pres...

MODELING MULTICOMPONENT ORGANIC CHEMICAL TRANSPORT IN THREE FLUID PHASE POROUS MEDIA

EPA Science Inventory

A two-dimensional finite-element model was developed to predict coupled transient flow and multicomponent transport of organic chemicals which can partition between nonaqueous phase liquid, water, gas and solid phases in porous media under the assumption of local chemical equilib...

Ignition transient analysis of solid rocket motor

NASA Technical Reports Server (NTRS)

Han, Samuel S.

1990-01-01

To predict pressure-time and thrust-time behavior of solid rocket motors, a one-dimensional numerical model is developed. The ignition phase of solid rocket motors (time less than 0.4 sec) depends critically on complex interactions among many elements, such as rocket geometry, heat and mass transfer, flow development, and chemical reactions. The present model solves the mass, momentum, and energy equations governing the transfer processes in the rocket chamber as well as the attached converging-diverging nozzle. A qualitative agreement with the SRM test data in terms of head-end pressure gradient and the total thrust build-up is obtained. Numerical results show that the burning rate in the star-segmented head-end section and the erosive burning are two important parameters in the ignition transient of the solid rocket motor (SRM).

The Role of Rhenium on the Temporal Evolution of the Nanostructure of a Model Ni-Al-Cr-Re Superalloy

NASA Technical Reports Server (NTRS)

Yoon, Kevin E.; Noebe, Ronald D.; Seidman, David N.

2004-01-01

Rhenium (2 at.%) additions to a model Ni-8.5 at.% Cr-10 at.% Al alloy are studied with respect to its effects on the temporal evolution of the nanostructure and the partitioning behavior of the four elements between the gamma (fcc) and gamma' (L1(sub 2)) phases. Chemical evolution of this quaternary alloy aged at 1073 K from 0.25 to 264 h, is investigated by three-dimensional atom-probe (3DAP) microscopy. The morphology of gamma'-precipitates remains spheroidal, even at an aging time of 264 h. The results demonstrate that Re slows the coarsening of gamma'-precipitates, in comparison to the ternary Ni-10 at.% A1-8.5 at.% Cr alloy at 1073 K.

Nano-Nucleation Characteristic of Cu-Ag Alloy Directly Electrodeposited on W Diffusion Barrier for Microelectronic Device Interconnect.

PubMed

Kim, Kang O; Kim, Sunjung

2016-05-01

Cu-Ag alloy interconnect is promising for ultra-large-scale integration (ULSI) microelectronic system of which device dimension keeps shrinking. In this study, seedless electrodeposition of Cu-Ag alloy directly on W diffusion barrier as interconnect technology is presented in respect of nano-nucleation control. Chemical equilibrium state of electrolyte was fundamentally investigated according to the pH of electrolyte because direct nano-nucleation of Cu-Ag alloy on W surface is challenging. Chelation behavior of Cu2+ and Ag+ ions with citrate (Cit) and ammonia ligands was dependent on the pH of electrolyte. The amount and kind of Cu- and Ag-based complexes determine the deposition rate, size, elemental composition, and surface morphology of Cu-Ag alloy nano-nuclei formed on W surface.

Separation of Niobium and Tantalum Pentafluoride by Selective Precipitation Using p-Phenylenediamine

NASA Astrophysics Data System (ADS)

Nete, M.; Purcell, W.; Nel, J. T.

2016-11-01

The similarity between Ta and Nb chemistry makes it difficult to find the appropriate reagents and chemical reactions for the separation of the two elements. This study investigated the precipitation behavior of TaF5 and NbF5 with p-phenylenediamine (PPDA). PPDA preferentially precipitated Nb from a 1:1 ratio of NbF5 and TaF5. Niobium recoveries of >80%, and only 4% Ta, were found in the precipitate of the reaction between (Nb/Ta)F5 and PPDA in ethanol. A separation factor of 100(9) indicated the potential for successful separation of Nb and Ta in a fluoride environment. A spectrophotometric study of the formation ratio of the newly formed Nb compound indicated a 1:1 metal:ligand ratio.

Chemistry of green encapsulating molding compounds at interfaces with other materials in electronic devices

NASA Astrophysics Data System (ADS)

Scandurra, A.; Zafarana, R.; Tenya, Y.; Pignataro, S.

2004-07-01

The interface chemistry between encapsulating epoxy phenolic molding compound (EMC) containing phosphorous based organic flame retardant (the so called "green materials") and copper oxide-hydroxide and aluminum oxide-hydroxide surfaces have been studied in comparison with "conventional" EMC containing bromine and antimony as flame retardant. These green materials are designed to reduce the presence of toxic elements in the electronic packages and, consequently, in the environment. For the study were used a Scanning Acoustic Microscopy for delamination measurements, a dynamometer for the pull strength measurements and an ESCA spectrometer for chemical analysis of the interface. The general behavior of the green compound in terms of delamination, adhesion, and corrosion is found better or at least comparable than that of the conventional EMC.

Chemistry of impact events on Mercury

NASA Astrophysics Data System (ADS)

Berezhnoy, Alexey A.

2018-01-01

Based on the equilibrium thermochemical approach and quenching theory, formation of molecules and dust grains in impact-produced clouds formed after collisions between meteoroids and Mercury is considered. Based on observations of Al, Fe, and Mn atoms in the exosphere of Mercury and new results of studies of the elemental composition of the surface of Mercury, quenching temperatures and pressures of main chemical reactions and condensation of dust particles were estimated. The behavior of the main Na-, K-, Ca-, Fe-, Al-, Mn-, Mg-, Si-, Ti, Ni-, Cr-, Co, Zn-, O-, H-, S-, C-, Cl-, N-, and P-containing species delivered to the Hermean exosphere during meteoroid impacts was studied. The importance of meteoroid bombardment as a source of Na, K, Ca, Fe, Al, Mn, Mg, and O atoms in the exosphere of Mercury is discussed.

The relationship between mantle pH and the deep nitrogen cycle

NASA Astrophysics Data System (ADS)

Mikhail, Sami; Barry, Peter H.; Sverjensky, Dimitri A.

2017-07-01

Nitrogen is distributed throughout all terrestrial geological reservoirs (i.e., the crust, mantle, and core), which are in a constant state of disequilibrium due to metabolic factors at Earth's surface, chemical weathering, diffusion, and deep N fluxes imposed by plate tectonics. However, the behavior of nitrogen during subduction is the subject of ongoing debate. There is a general consensus that during the crystallization of minerals from melts, monatomic nitrogen behaves like argon (highly incompatible) and ammonium behaves like potassium and rubidium (which are relatively less incompatible). Therefore, the behavior of nitrogen is fundamentally underpinned by its chemical speciation. In aqueous fluids, the controlling factor which determines if nitrogen is molecular (N2) or ammonic (inclusive of both NH4+ and NH30) is oxygen fugacity, whereas pH designates if ammonic nitrogen is NH4+ or NH30. Therefore, to address the speciation of nitrogen at high pressures and temperatures, one must also consider pH at the respective pressure-temperature conditions. To accomplish this goal we have used the Deep Earth Water Model (DEW) to calculate the activities of aqueous nitrogen from 1-5 GPa and 600-1000 °C in equilibrium with a model eclogite-facies mineral assemblage of jadeite + kyanite + quartz/coesite (metasediment), jadeite + pyrope + talc + quartz/coesite (metamorphosed mafic rocks), and carbonaceous eclogite (metamorphosed mafic rocks + elemental carbon). We then compare these data with previously published data for the speciation of aqueous nitrogen across these respective P-T conditions in equilibrium with a model peridotite mineral assemblage (Mikhail and Sverjensky, 2014). In addition, we have carried out full aqueous speciation and solubility calculations for the more complex fluids in equilibrium with jadeite + pyrope + kyanite + diamond, and for fluids in equilibrium with forsterite + enstatite + pyrope + diamond. Our results show that the pH of the fluid is controlled by mineralogy for a given pressure and temperature, and that pH can vary by several units in the pressure-temperature range of 1-5 GPa and 600-1000 °C. Our data show that increasing temperature stabilizes molecular nitrogen and increasing pressure stabilizes ammonic nitrogen. Our model also predicts a stark difference for the dominance of ammonic vs. molecular and ammonium vs. ammonia for aqueous nitrogen in equilibrium with eclogite-facies and peridotite mineralogies, and as a function of the total dissolved nitrogen in the aqueous fluid where lower N concentrations favor aqueous ammonic nitrogen stabilization and higher N concentrations favor aqueous N2. Overall, we present thermodynamic evidence for nitrogen to be reconsidered as an extremely dynamic (chameleon) element whose speciation and therefore behavior is determined by a combination of temperature, pressure, oxygen fugacity, chemical activity, and pH. We show that altering the mineralogy in equilibrium with the fluid can lead to a pH shift of up to 4 units at 5 GPa and 1000 °C. Therefore, we conclude that pH imparts a strong control on nitrogen speciation, and thus N flux, and should be considered a significant factor in high temperature geochemical modeling in the future. Finally, our modelling demonstrates that pH plays an important role in controlling speciation, and thus mass transport, of Eh-pH sensitive elements at temperatures up to at least 1000 °C.

Hard and soft acids and bases: atoms and atomic ions.

PubMed

Reed, James L

2008-07-07

The structural origin of hard-soft behavior in atomic acids and bases has been explored using a simple orbital model. The Pearson principle of hard and soft acids and bases has been taken to be the defining statement about hard-soft behavior and as a definition of chemical hardness. There are a number of conditions that are imposed on any candidate structure and associated property by the Pearson principle, which have been exploited. The Pearson principle itself has been used to generate a thermodynamically based scale of relative hardness and softness for acids and bases (operational chemical hardness), and a modified Slater model has been used to discern the electronic origin of hard-soft behavior. Whereas chemical hardness is a chemical property of an acid or base and the operational chemical hardness is an experimental measure of it, the absolute hardness is a physical property of an atom or molecule. A critical examination of chemical hardness, which has been based on a more rigorous application of the Pearson principle and the availability of quantitative measures of chemical hardness, suggests that the origin of hard-soft behavior for both acids and bases resides in the relaxation of the electrons not undergoing transfer during the acid-base interaction. Furthermore, the results suggest that the absolute hardness should not be taken as synonymous with chemical hardness but that the relationship is somewhat more complex. Finally, this work provides additional groundwork for a better understanding of chemical hardness that will inform the understanding of hardness in molecules.

On the nature and shape of tubulin trails: implications on microtubule self-organization.

PubMed

Glade, Nicolas

2012-06-01

Microtubules, major elements of the cell skeleton are, most of the time, well organized in vivo, but they can also show self-organizing behaviors in time and/or space in purified solutions in vitro. Theoretical studies and models based on the concepts of collective dynamics in complex systems, reaction-diffusion processes and emergent phenomena were proposed to explain some of these behaviors. In the particular case of microtubule spatial self-organization, it has been advanced that microtubules could behave like ants, self-organizing by 'talking to each other' by way of hypothetic (because never observed) concentrated chemical trails of tubulin that are expected to be released by their disassembling ends. Deterministic models based on this idea yielded indeed like-looking spatio-temporal self-organizing behaviors. Nevertheless the question remains of whether microscopic tubulin trails produced by individual or bundles of several microtubules are intense enough to allow microtubule self-organization at a macroscopic level. In the present work, by simulating the diffusion of tubulin in microtubule solutions at the microscopic scale, we measure the shape and intensity of tubulin trails and discuss about the assumption of microtubule self-organization due to the production of chemical trails by disassembling microtubules. We show that the tubulin trails produced by individual microtubules or small microtubule arrays are very weak and not elongated even at very high reactive rates. Although the variations of concentration due to such trails are not significant compared to natural fluctuations of the concentration of tubuline in the chemical environment, the study shows that heterogeneities of biochemical composition can form due to microtubule disassembly. They could become significant when produced by numerous microtubule ends located in the same place. Their possible formation could play a role in certain conditions of reaction. In particular, it gives a mesoscopic basis to explain the collective dynamics observed in excitable microtubule solutions showing the propagation of concentration waves of microtubules at the millimeter scale, although we doubt that individual microtubules or bundles can behave like molecular ants.

Chemical thermodynamic data. 1. The concept of links to the chemical elements and the historical development of key thermodynamic data [plus Supplementary Electronic Annex 2

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wolery, Thomas J.; Jove Colon, Carlos F.

Chemical thermodynamic data remain a keystone for geochemical modeling and reactive transport simulation as applied to an increasing number of applications in the earth sciences, as well as applications in other areas including metallurgy, material science, and industrial process design. The last century has seen the development of a large body of thermodynamic data and a number of major compilations. The past several decades have seen the development of thermodynamic databases in digital form designed to support computer calculations. However, problems with thermodynamic data appear to be persistent. One problem pertains to the use of inconsistent primary key reference data.more » Such data pertain to elemental reference forms and key, stoichiometrically simple chemical species including metal oxides, CO 2, water, and aqueous species such as Na + and Cl -. A consistent set of primary key data (standard Gibbs energies, standard enthalpies, and standard entropies for key chemical species) for 298.15K and 1 bar pressure is essential. Thermochemical convention is to define the standard Gibbs energy and the standard enthalpy of an individual chemical species in terms of formation from reference forms of the constituent chemical elements. We propose a formal concept of “links” to the elemental reference forms. This concept involves a documented understanding of all reactions and calculations leading to values for a formation property (standard Gibbs energy or enthalpy). A valid link consists of two parts: (a) the path of reactions and corrections and (b) the associated data, which are key data. Such a link differs from a bare “key” or “reference” datum in that it requires additional information. Some or all of its associated data may also be key data. In evaluating a reported thermodynamic datum, one should identify the links to the chemical elements, a process which can be time-consuming and which may lead to a dead end (an incomplete link). The use of two or more inconsistent links to the same elemental reference form in a thermodynamic database will result in an inconsistency in the database. Thus, in constructing a database, it is important to establish a set of reliable links (generally resulting in a set of primary reference data) and then correct all data adopted subsequently for consistency with that set. Recommended values of key data have not been constant through history. We review some of this history through the lens of major compilations and other influential reports, and note a number of problem areas. Finally, we illustrate the concepts developed in this paper by applying them to some key species of geochemical interest, including liquid water; quartz and aqueous silica; and gibbsite, corundum, and the aqueous aluminum ion.« less

Chemical thermodynamic data. 1. The concept of links to the chemical elements and the historical development of key thermodynamic data

NASA Astrophysics Data System (ADS)

Wolery, Thomas J.; Jové Colón, Carlos F.

2017-09-01

Chemical thermodynamic data remain a keystone for geochemical modeling and reactive transport simulation as applied to an increasing number of applications in the earth sciences, as well as applications in other areas including metallurgy, material science, and industrial process design. The last century has seen the development of a large body of thermodynamic data and a number of major compilations. The past several decades have seen the development of thermodynamic databases in digital form designed to support computer calculations. However, problems with thermodynamic data appear to be persistent. One problem pertains to the use of inconsistent primary key reference data. Such data pertain to elemental reference forms and key, stoichiometrically simple chemical species including metal oxides, CO2, water, and aqueous species such as Na+ and Cl-. A consistent set of primary key data (standard Gibbs energies, standard enthalpies, and standard entropies for key chemical species) for 298.15 K and 1 bar pressure is essential. Thermochemical convention is to define the standard Gibbs energy and the standard enthalpy of an individual chemical species in terms of formation from reference forms of the constituent chemical elements. We propose a formal concept of "links" to the elemental reference forms. This concept involves a documented understanding of all reactions and calculations leading to values for a formation property (standard Gibbs energy or enthalpy). A valid link consists of two parts: (a) the path of reactions and corrections and (b) the associated data, which are key data. Such a link differs from a bare "key" or "reference" datum in that it requires additional information. Some or all of its associated data may also be key data. In evaluating a reported thermodynamic datum, one should identify the links to the chemical elements, a process which can be time-consuming and which may lead to a dead end (an incomplete link). The use of two or more inconsistent links to the same elemental reference form in a thermodynamic database will result in an inconsistency in the database. Thus, in constructing a database, it is important to establish a set of reliable links (generally resulting in a set of primary reference data) and then correct all data adopted subsequently for consistency with that set. Recommended values of key data have not been constant through history. We review some of this history through the lens of major compilations and other influential reports, and note a number of problem areas. Finally, we illustrate the concepts developed in this paper by applying them to some key species of geochemical interest, including liquid water; quartz and aqueous silica; and gibbsite, corundum, and the aqueous aluminum ion.

Chemical thermodynamic data. 1. The concept of links to the chemical elements and the historical development of key thermodynamic data [plus Supplementary Electronic Annex 2

DOE PAGES

Wolery, Thomas J.; Jove Colon, Carlos F.

2016-09-26

Chemical thermodynamic data remain a keystone for geochemical modeling and reactive transport simulation as applied to an increasing number of applications in the earth sciences, as well as applications in other areas including metallurgy, material science, and industrial process design. The last century has seen the development of a large body of thermodynamic data and a number of major compilations. The past several decades have seen the development of thermodynamic databases in digital form designed to support computer calculations. However, problems with thermodynamic data appear to be persistent. One problem pertains to the use of inconsistent primary key reference data.more » Such data pertain to elemental reference forms and key, stoichiometrically simple chemical species including metal oxides, CO 2, water, and aqueous species such as Na + and Cl -. A consistent set of primary key data (standard Gibbs energies, standard enthalpies, and standard entropies for key chemical species) for 298.15K and 1 bar pressure is essential. Thermochemical convention is to define the standard Gibbs energy and the standard enthalpy of an individual chemical species in terms of formation from reference forms of the constituent chemical elements. We propose a formal concept of “links” to the elemental reference forms. This concept involves a documented understanding of all reactions and calculations leading to values for a formation property (standard Gibbs energy or enthalpy). A valid link consists of two parts: (a) the path of reactions and corrections and (b) the associated data, which are key data. Such a link differs from a bare “key” or “reference” datum in that it requires additional information. Some or all of its associated data may also be key data. In evaluating a reported thermodynamic datum, one should identify the links to the chemical elements, a process which can be time-consuming and which may lead to a dead end (an incomplete link). The use of two or more inconsistent links to the same elemental reference form in a thermodynamic database will result in an inconsistency in the database. Thus, in constructing a database, it is important to establish a set of reliable links (generally resulting in a set of primary reference data) and then correct all data adopted subsequently for consistency with that set. Recommended values of key data have not been constant through history. We review some of this history through the lens of major compilations and other influential reports, and note a number of problem areas. Finally, we illustrate the concepts developed in this paper by applying them to some key species of geochemical interest, including liquid water; quartz and aqueous silica; and gibbsite, corundum, and the aqueous aluminum ion.« less

Elemental Etymology: What's in a Name?

ERIC Educational Resources Information Center

Ball, David W.

1985-01-01

Examines the origin of the names (or etymologies) of the chemical elements. Includes tables listing elements: (1) with names of obscure origin; (2) named for colors; (3) named after real or mythical people; (4) named after places; (5) named after heavenly bodies; and (6) having names of miscellaneous origin. (JN)

Biodiversity of mineral nutrient and trace element accumulation in Arabidopsis thaliana

USDA-ARS?s Scientific Manuscript database

In order to grow on soils that vary widely in chemical composition, plants have evolved mechanisms for regulating the elemental composition of their tissues to balance the mineral nutrient and trace element bioavailability in the soil with the requirements of the plant for growth and development. T...

Relativistic Effects and the Chemistry of the Heaviest Main-Group Elements

ERIC Educational Resources Information Center

Thayer, John S.

2005-01-01

The chemical properties of the heaviest main-group elements often show features not found in their lighter counterparts while relativistic effects play an important role in the chemistry of these elements. The unusual properties and their relation to relativistic effects with emphasis on the new research are emphasized.

Emergy Evaluations of the Global Biogeochemical Cycles of Six Biologically Active Elements and Two Compounds

EPA Science Inventory

Estimates of the emergy carried by the flows of biologically active elements (BAE) and compounds are needed to accurately evaluate the near and far field effects of anthropogenic wastes. The transformities and specific emergies of these elements and of their different chemical sp...

Elemental Food for Thought

ERIC Educational Resources Information Center

Cady, Susan

2005-01-01

One of the first tasks students learn in chemistry is to pronounce and spell the names of elements and learn their corresponding chemical symbols. Repetitive oral recitation is commonly used to learn this information, but games and puzzles can make this task creative, variable, and fun. Elemental Food for Thought is a puzzlelike activity that…

Low Young's modulus Ti-based porous bulk glassy alloy without cytotoxic elements.

PubMed

Nicoara, M; Raduta, A; Parthiban, R; Locovei, C; Eckert, J; Stoica, M

2016-05-01

A new a biocompatible Ti42Zr40Ta3Si15 (atomic %) porous bulk glassy alloy was produced by combination of rapid solidification and powder metallurgy techniques. Amorphous alloy ribbons were fabricated by melt spinning, i.e. extremely fast quenching the molten alloy with 10(6)K/s from T=1973K down to room temperature. The ribbons were then cryo-milled at liquid nitrogen temperature in order to produce powder, which was subsequently hot pressed. The resulting thick pellets have a porosity of about 14vol%, a high compression strength of 337MPa and a Young's modulus of about E=52GPa, values very close to those characteristic of cortical bone. Moreover, the morphology of the samples is very similar to that of cortical bone. The biocompatibility, which is due to the absence of any toxic element in the chemical composition, together with the suitable mechanical behavior, make these samples promising for orthopedic and dentistry applications. Ti-based alloys are nowadays the standard solution for biomedical implants. However, both the conventional crystalline and amorphous alloys have higher rigidity as the human bone, leading to the damage of the bone at the interface, and contains harmful elements like vanadium, aluminum, nickel or beryllium. The hierarchical porous structures based on glassy alloys with biocompatible elements is a much better alternative. This work presents for the first time the manufacturing of such porous bodies starting from Ti-based amorphous alloy ribbons, which contains only non-harmful elements. The morphology and the compressive mechanical properties of these new products are analyzed in regard with those characteristic to the cortical bone. Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Trace elements and organic contaminants in stream sediments from the Red River of the North Basin

USGS Publications Warehouse

Brigham, M.E.; Tornes, L.H.

1996-01-01

To assess the presence and distribution of a variety of hydro-phobic chemicals in streams in the Red River of the North Basin, bottom sediments were analyzed for trace elements, organochlorines, and polycyclic aromatic hydrocarbons (PAHs). Glaciolacustrine clays and carbonate minerals are common in fine sediments of the region, and can help explain the distribution of many elements. Aluminum (Al), an indicator of glaciolacustrine clay minerals, correlates strongly (r>0.75, p<0.05) with Cr, Co, Fe, La, Li, K, Sc, and Ti; and moderately (0.55

Detailed Abundances of Planet-hosting Wide Binaries. I. Did Planet Formation Imprint Chemical Signatures in the Atmospheres of HD 20782/81?

NASA Astrophysics Data System (ADS)

Mack, Claude E., III; Schuler, Simon C.; Stassun, Keivan G.; Norris, John

2014-06-01

Using high-resolution, high signal-to-noise echelle spectra obtained with Magellan/MIKE, we present a detailed chemical abundance analysis of both stars in the planet-hosting wide binary system HD 20782 + HD 20781. Both stars are G dwarfs, and presumably coeval, forming in the same molecular cloud. Therefore we expect that they should possess the same bulk metallicities. Furthermore, both stars also host giant planets on eccentric orbits with pericenters lsim0.2 AU. Here, we investigate if planets with such orbits could lead to the host stars ingesting material, which in turn may leave similar chemical imprints in their atmospheric abundances. We derived abundances of 15 elements spanning a range of condensation temperature, T C ≈ 40-1660 K. The two stars are found to have a mean element-to-element abundance difference of 0.04 ± 0.07 dex, which is consistent with both stars having identical bulk metallicities. In addition, for both stars, the refractory elements (T C >900 K) exhibit a positive correlation between abundance (relative to solar) and T C, with similar slopes of ≈1×10-4 dex K-1. The measured positive correlations are not perfect; both stars exhibit a scatter of ≈5×10-5 dex K-1 about the mean trend, and certain elements (Na, Al, Sc) are similarly deviant in both stars. These findings are discussed in the context of models for giant planet migration that predict the accretion of H-depleted rocky material by the host star. We show that a simple simulation of a solar-type star accreting material with Earth-like composition predicts a positive—but imperfect—correlation between refractory elemental abundances and T C. Our measured slopes are consistent with what is predicted for the ingestion of 10-20 Earths by each star in the system. In addition, the specific element-by-element scatter might be used to distinguish between planetary accretion and Galactic chemical evolution scenarios. The data presented herein were obtained at the Las Campanas Observatory with the Magellan/MIKE spectrograph.

Influence of arc current and pressure on non-chemical equilibrium air arc behavior

NASA Astrophysics Data System (ADS)

Yi, WU; Yufei, CUI; Jiawei, DUAN; Hao, SUN; Chunlin, WANG; Chunping, NIU

2018-01-01

The influence of arc current and pressure on the non-chemical equilibrium (non-CE) air arc behavior of a nozzle structure was investigated based on the self-consistent non-chemical equilibrium model. The arc behavior during both the arc burning and arc decay phases were discussed at different currents and different pressures. We also devised the concept of a non-equilibrium parameter for a better understanding of non-CE effects. During the arc burning phase, the increasing current leads to a decrease of the non-equilibrium parameter of the particles in the arc core, while the increasing pressure leads to an increase of the non-equilibrium parameter of the particles in the arc core. During the arc decay phase, the non-CE effect will decrease by increasing the arc burning current and the nozzle pressure. Three factors together—convection, diffusion and chemical reactions—influence non-CE behavior.

Constitutive Behavior of Reinforced Concrete Membrane Elements under Tri-directional Shear

NASA Astrophysics Data System (ADS)

Labib, Moheb

The two-dimensional behavior of typical reinforced concrete (RC) structures has been extensively studied in the past several decades by investigating the constitutive behavior of full-scale reinforced concrete elements subjected to a bi-axial state of stress. In order to understand the true behavior of many large complex structures, the goal of this investigation is to develop new constitutive relationships for RC elements subjected to tri-directional shear stresses. Recently, additional out-of-plane jacks were installed on the panel tester at University of Houston so that concrete elements could be subjected to tri-directional shear stresses. This upgrade makes the panel tester the only one of its kind in the US that is capable of applying such combinations of stresses on full-scale reinforced concrete elements. This dissertation presents the details of the mounting and installation of the additional hydraulic jacks on the universal panel tester. The experimental program includes a series of seven reinforced concrete elements subjected to different combinations of in-plane and out-of-plane shear stresses. Increasing the applied out-of-plane shear stresses reduced the membrane shear strength of the elements. The effect of applying out-of-plane shear stresses on the in-plane shear strength was represented by modifying the softening coefficient in the compression stress strain curve of concrete struts. The modified model was able to capture the behavior and the ultimate capacity of the tested elements. The effect of the in-plane shear reinforcement ratio on the interaction between in-plane and out-of-plane shear stresses was evaluated. The model was implemented in the Finite Element package FEAP and was used to predict the ultimate capacity of many structures subjected to a combination of in-plane and out-of-plane shear stresses. The results of the analytical model were used to develop simplified design equations for members subjected to bi-directional shear loads. The applied out-of-plane shear load was resolved in two equal out-of-plane shear components to construct tri-directional shear interaction diagrams.

Behavioral Health and Performance Element: Tools and Technologies

NASA Technical Reports Server (NTRS)

Leveton, Lauren B.

2009-01-01

This slide presentation reviews the research into the Behavioral Health and Performance (BHP) of the Human Research Program. The program element goal is to identify, characterize and prevent or reduce behavioral health and performance risks associated with space travel, exploration, and return to terrestrial life. To accomplish this goal the program focuses on applied research that is designed to yield deliverables that reduce risk. There are several different elements that are of particular interest: Behavioral Medicine, Sleep, and team composition, and team work. In order to assure success for NASA missions the Human Research Program develops and validate the standards for each of the areas of interest. There is discussion of the impact on BHP while astronauts are on Long Duration Missions. The effort in this research is to create tools to meet the BHP concerns, these prospective tools are reviewed.