Low-δ13C carbonates in the Miocene basalt of the northern margin of the North China Craton: Implications for deep carbon recycling

NASA Astrophysics Data System (ADS)

Zhang, Huiting; Liu, Yongsheng; Hu, Zhaochu; Zong, Keqing; Chen, Haihong; Chen, Chunfei

2017-08-01

Three types of carbonates have been found in the Miocene basalt in the Dongbahao area (Inner Mongolia), including wide veins and veinlets of carbonate in basalt and carbonates in peridotite xenoliths. Except for the dolomitic zonation in the basalt, all of the carbonates are calcite. Despite their different appearances, they share almost identical geochemical characteristics of low LILE (low large ion lithophile element), HFSE (high field strength element), and REE (rare earth elements) contents (ΣREE = 0.51-137 ppm); negative Ce anomalies; and low Ce/Pb ratios (0.51-74.5). Moreover, they show high δ18OSMOW values (20.95-22.61‰) and 87Sr/86Sr ratios (0.7087 ± 0.0003 (1σ, n = 17)). These characteristics indicate a sedimentary precursor for these carbonates. However, the occurrence and petrographic characteristics imply an igneous origin for the carbonates rather than a hypergene process. Further, the trace element compositions of the silicate melt and carbonate melt in the calcite-dolomite-silicate zonations fall on the same variation lines in the plots of Y-Ho, La-Yb, Li-Pb and Ba-Cu. It is suggested that these melts could have evolved from one magma system or could have been equilibrated. Given the partition coefficients of REEs and alkali elements (Cs, Rb, and K) between the carbonate melt and silicate melt, it can be inferred that these melts could have been formed from a primary H2O-Si-bearing Mg-Ca-carbonate melt by an immiscibility process at 1-3 GPa. Considering the southward subduction of the Paleo-Asian ocean along the northern margin of the North China Craton (NCC), these carbonate melts could have been derived from the melting of subducted sedimentary carbonate rocks. Interestingly, these carbonates have quite depleted carbon isotopic compositions (δ13CPDB = -8.23‰ to -11.76‰) but moderate δ18OSMOW values, implying coupled H2O-CO2 degassing during subduction and/or recycling to the Earth's surface. Low-δ13CPBD carbonates appearing at the global scale may suggest an underestimated path of CO2 emission back to the atmosphere.

Quality assurance and quality control for thermal/optical analysis of aerosol samples for organic and elemental carbon.

PubMed

Chow, Judith C; Watson, John G; Robles, Jerome; Wang, Xiaoliang; Chen, L-W Antony; Trimble, Dana L; Kohl, Steven D; Tropp, Richard J; Fung, Kochy K

2011-12-01

Accurate, precise, and valid organic and elemental carbon (OC and EC, respectively) measurements require more effort than the routine analysis of ambient aerosol and source samples. This paper documents the quality assurance (QA) and quality control (QC) procedures that should be implemented to ensure consistency of OC and EC measurements. Prior to field sampling, the appropriate filter substrate must be selected and tested for sampling effectiveness. Unexposed filters are pre-fired to remove contaminants and acceptance tested. After sampling, filters must be stored in the laboratory in clean, labeled containers under refrigeration (<4 °C) to minimize loss of semi-volatile OC. QA activities include participation in laboratory accreditation programs, external system audits, and interlaboratory comparisons. For thermal/optical carbon analyses, periodic QC tests include calibration of the flame ionization detector with different types of carbon standards, thermogram inspection, replicate analyses, quantification of trace oxygen concentrations (<100 ppmv) in the helium atmosphere, and calibration of the sample temperature sensor. These established QA/QC procedures are applicable to aerosol sampling and analysis for carbon and other chemical components.

Multi-element compound specific stable isotope analysis of chlorinated aliphatic contaminants derived from chlorinated pitches.

PubMed

Filippini, Maria; Nijenhuis, Ivonne; Kümmel, Steffen; Chiarini, Veronica; Crosta, Giovanni; Richnow, Hans H; Gargini, Alessandro

2018-05-30

Tetrachloroethene and trichloroethene are typical by-products of the industrial production of chloromethanes. These by-products are known as "chlorinated pitches" and were often dumped in un-contained waste disposal sites causing groundwater contaminations. Previous research showed that a strongly depleted stable carbon isotope signature characterizes chlorinated compounds associated with chlorinated pitches whereas manufactured commercial compounds have more enriched carbon isotope ratios. The findings were restricted to a single case study and one element (i.e. carbon). This paper presents a multi-element Compound-Specific Stable Isotope Analysis (CSIA, including carbon, chlorine and hydrogen) of chlorinated aliphatic contaminants originated from chlorinated pitches at two sites with different hydrogeology and different producers of chloromethanes. The results show strongly depleted carbon signatures at both sites whereas the chlorine and the hydrogen signatures are comparable to those presented in the literature for manufactured commercial compounds. Multi-element CSIA allowed the identification of sources and site-specific processes affecting chloroethene transformation in groundwater as a result of emergency remediation measures. CSIA turned out to be an effective forensic tool to address the liability for the contamination, leading to a conviction for the crimes of unintentional aggravated public water supply poisoning and environmental disaster. Copyright © 2018 Elsevier B.V. All rights reserved.

Reactions involving the heterolytic cleavage of carbon-element σ-bonds by Grignard reagents

NASA Astrophysics Data System (ADS)

Polivin, Yurii N.; Karakhanov, Robert A.; Postnov, Victor N.

1990-03-01

The reactions involving the heterolysis of the C-O, C-C, C-N, C-S, C-Cl, etc. bonds by organomagnesium compounds are examined and the nature of this interesting phenomenon is analysed. On the basis of the analysis of the characteristic features of the cleavage under discussion, it is shown that the heterolysis of the carbon-element bond is, firstly, a general reaction for all classes of organic compounds (provided that two conditions are observed: the substrate molecule must fragment into two stable species — a carbonium ion and an anion — and the strength of the Lewis acid properties should be adequate for the occurrence of the above reaction) and, secondly, the heterolysis of the carbon-element bond is one of the independent pathways in the reactions of the Grignard reagents. The bibliography includes 158 references.

Formation evaluation of gas hydrate-bearing marine sediments on the Blake Ridge with downhole geochemical log measurements

USGS Publications Warehouse

Collett, T.S.; Wendlandt, R.F.

2000-01-01

The analyses of downhole log data from Ocean Drilling Program (ODP) boreholes on the Blake Ridge at Sites 994, 995, and 997 indicate that the Schlumberger geochemical logging tool (GLT) may yield useful gas hydrate reservoir data. In neutron spectroscopy downhole logging, each element has a characteristic gamma ray that is emitted from a given neutron-element interaction. Specific elements can be identified by their characteristic gamma-ray signature, with the intensity of emission related to the atomic elemental concentration. By combining elemental yields from neutron spectroscopy logs, reservoir parameters including porosities, lithologies, formation fluid salinities, and hydrocarbon saturations (including gas hydrate) can be calculated. Carbon and oxygen elemental data from the GLT was used to determine gas hydrate saturations at all three sites (Sites 994, 995, and 997) drilled on the Blake Ridge during Leg 164. Detailed analyses of the carbon and oxygen content of various sediments and formation fluids were used to construct specialized carbon/oxygen ratio (COR) fan charts for a series of hypothetical gas hydrate accumulations. For more complex geologic systems, a modified version of the standard three-component COR hydrocarbon saturation equation was developed and used to calculate gas hydrate saturations on the Blake Ridge. The COR-calculated gas hydrate saturations (ranging from about 2% to 14% bulk volume gas hydrate) from the Blake Ridge compare favorably to the gas hydrate saturations derived from electrical resistivity log measurements.

Strength Evaluation and Failure Prediction of Short Carbon Fiber Reinforced Nylon Spur Gears by Finite Element Modeling

NASA Astrophysics Data System (ADS)

Hu, Zhong; Hossan, Mohammad Robiul

2013-06-01

In this paper, short carbon fiber reinforced nylon spur gear pairs, and steel and unreinforced nylon spur gear pairs have been selected for study and comparison. A 3D finite element model was developed to simulate the multi-axial stress-strain behaviors of the gear tooth. Failure prediction has been conducted based on the different failure criteria, including Tsai-Wu criterion. The tooth roots, where has stress concentration and the potential for failure, have been carefully investigated. The modeling results show that the short carbon fiber reinforced nylon gear fabricated by properly controlled injection molding processes can provide higher strength and better performance.

Producing carbon stripper foils containing boron

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

Stoner, J. O. Jr.

2012-12-19

Parameters being actively tested by the accelerator community for the purpose of extending carbon stripper foil lifetimes in fast ion beams include methods of deposition, parting agents, mounting techniques, support (fork) materials, and inclusion of alloying elements, particularly boron. Specialized production apparatus is required for either sequential deposition or co-deposition of boron in carbon foils. A dual-use vacuum evaporator for arc evaporation of carbon and electron-beam evaporation of boron and other materials has been built for such development. Production of both carbon and boron foils has begun and improvements are in progress.

Effect of Swirl on an Unstable Single-Element Gas-Gas Rocket Engine

DTIC Science & Technology

2014-06-01

at 300 K, and the combustor is filled with a mixture of water and carbon dioxide at 1500 K. The warmer temperature in the combustor enables the auto...a variety of configurations including gas turbines and rocket engines.4–13 The single-element engine chosen for this study is the continuously...combustion systems including gas turbines , rocket engines, and industrial furnaces. Swirl can have dramatic effects on the flowfield; these include jet growth

Tracing iron-carbon redox from surface to core

NASA Astrophysics Data System (ADS)

McCammon, C. A.; Cerantola, V.; Bykova, E.; Kupenko, I.; Bykov, M.; Chumakov, A. I.; Rüffer, R.; Dubrovinsky, L. S.

2017-12-01

Numerous redox reactions separate the Earth's oxidised surface from its reduced core. Many involve iron, the Earth's most abundant element and the mantle's most abundant transition element. Most iron redox reactions (although not all) also involve other elements, including carbon, where iron-carbon interactions drive a number of important processes within the Earth, for example diamond formation. Many of the Earth's redox boundaries are sharp, much like the seismic properties that define them, for example between the lower mantle and the core. Other regions that appear seismically homogeneous, for example the lower mantle, harbour a wealth of reactions between oxidised and reduced phases of iron and carbon. We have undertaken many experiments at high pressure and high temperature on phases containing iron and carbon using synchrotron-based X-rays to probe structures and iron oxidation states. Results demonstrate the dominant role that crystal structures play in determining the stable oxidation states of iron and carbon, even when oxygen fugacity (and common sense) would suggest otherwise. Iron in bridgmanite, for example, occurs predominantly in its oxidised form (ferric iron) throughout the lower mantle, despite the inferred reducing conditions. Newly discovered structures of iron carbonate also stabilise ferric iron, while simultaneously reducing some carbon to diamond to balance charge. Other high-pressure iron carbonates appear to be associated with the emerging zoo of iron oxide phases, involving transitions between ferrous and ferric iron through the exchange of oxygen. The presentation will trace redox relations between iron and carbon from the Earth's surface to its core, with an emphasis on recent experimental results.

Experimental and Numerical Study on the Tensile Behaviour of UACS/Al Fibre Metal Laminate

NASA Astrophysics Data System (ADS)

Xue, Jia; Wang, Wen-Xue; Zhang, Jia-Zhen; Wu, Su-Jun; Li, Hang

2015-10-01

A new fibre metal laminate fabricated with aluminium sheets and unidirectionally arrayed chopped strand (UACS) plies is proposed. The UACS ply is made by cutting parallel slits into a unidirectional carbon fibre prepreg. The UACS/Al laminate may be viewed as aluminium laminate reinforced by highly aligned, discontinuous carbon fibres. The tensile behaviour of UACS/Al laminate, including thermal residual stress and failure progression, is investigated through experiments and numerical simulation. Finite element analysis was used to simulate the onset and propagation of intra-laminar fractures occurring within slits of the UACS plies and delamination along the interfaces. The finite element models feature intra-laminar cohesive elements inserted into the slits and inter-laminar cohesive elements inserted at the interfaces. Good agreement are obtained between experimental results and finite element analysis, and certain limitations of the finite element models are observed and discussed. The combined experimental and numerical studies provide a detailed understanding of the tensile behaviour of UACS/Al laminates.

Comprehensive laboratory measurements of biomass-burning emissions: 1. Emissions from Indonesian, African, and other fuels

NASA Astrophysics Data System (ADS)

Christian, T. J.; Kleiss, B.; Yokelson, R. J.; Holzinger, R.; Crutzen, P. J.; Hao, W. M.; Saharjo, B. H.; Ward, D. E.

2003-12-01

Trace gas and particle emissions were measured from 47 laboratory fires burning 16 regionally to globally significant fuel types. Instrumentation included the following: open-path Fourier transform infrared spectroscopy; proton transfer reaction mass spectrometry; filter sampling with subsequent analysis of particles with diameter <2.5 μm for organic and elemental carbon and other elements; and canister sampling with subsequent analysis by gas chromatography (GC)/flame ionization detector, GC/electron capture detector, and GC/mass spectrometry. The emissions of 26 compounds are reported by fuel type. The results include the first detailed measurements of the emissions from Indonesian fuels. Carbon dioxide, CO, CH4, NH3, HCN, methanol, and acetic acid were the seven most abundant emissions (in order) from burning Indonesian peat. Acetol (hydroxyacetone) was a major, previously unobserved emission from burning rice straw (21-34 g/kg). The emission factors for our simulated African fires are consistent with field data for African fires for compounds measured in both the laboratory and the field. However, the higher concentrations and more extensive instrumentation in this work allowed quantification of at least 10 species not previously quantified for African field fires (in order of abundance): acetaldehyde, phenol, acetol, glycolaldehyde, methylvinylether, furan, acetone, acetonitrile, propenenitrile, and propanenitrile. Most of these new compounds are oxygenated organic compounds, which further reinforces the importance of these reactive compounds as initial emissions from global biomass burning. A few high-combustion-efficiency fires emitted very high levels of elemental (black) carbon, suggesting that biomass burning may produce more elemental carbon than previously estimated.

Natural and anthropogenic controls on sediment composition of an arid coastal environment: Sharm Obhur, Red Sea, Saudi Arabia.

PubMed

Ghandour, I M; Basaham, A S; Basaham, S; Al-Washmi, H A; Al-Washmi, A; Masuda, H

2014-03-01

The present study investigated the natural and anthropogenic processes that control the composition of the bottom sediments of Sharm Obhur, Red Sea. Mineralogical analysis using XRD indicated that the sediments consist of carbonate and non-carbonate minerals. Elemental interrelationships allowed differentiating two groups of elements of different sources and origin. Elements that are in the same group are positively correlated, while they correlate negatively with elements of the other group. The first group includes silicon, Al, Fe, Mn, Mg, vanadium (V), chromium (Cr), Co, Ni, Cu, and Zn, whereas the other group includes Ca, Sr, and CaCO3. The highest concentration levels of the first group and the highest content of non-carbonate minerals were obtained from the sediments near the head of the sharm (zone A), whereas the sediments near the mouth of the sharm (zone B) yielded high concentrations of second group and carbonate minerals. Metal enrichment and contamination factors and pollution load index were calculated. The values of these indices differentiate two groups of metals: lithogenic and non-lithogenic. Except for lead (Pb) at one sampling site, metals in zone A sediments are of lithogenic source, supplied to the sharm either naturally by aeolian transportation and through Wadi Al-Kuraa'a during rare but major floods or by human activities such as dumping and shore protection. Non-lithogenic Cr, Pb, V, and Mn were documented from some sampling sites in zone B, and their occurrences are related to waste disposal and fossil fuel combustion.

Geochemistry and origin of regional dolomites

NASA Astrophysics Data System (ADS)

Hanson, G. N.; Meyers, W. J.

1989-12-01

The major goal of the carbonate research program at Stony Brook is to better understand the conditions and processes leading to regional diagenesis of carbonate rocks. Our research focuses on studies of ancient, massive dolostones, but we are also studying limestone diagenesis for its own importance, and as it relates to dolomitization. Our approach has been to carry out a very detailed petrographic and geochemical case study to the Mississippian Burlington-Keokuk Fms. of Iowa, Illinois and Missouri, and to develop this as a testing ground for new geochemical and modelling techniques, and for testing various models for regional dolomitization in epicontinental carbonates. The ideas and techniques developed in our Burlington-Keokuk studies are being expanded and applied to carbonate sequences of other ages (Devonian to Neogene), and other tectono-sedimentary settings. The emphasis of this report will be on new developments and results on the Burlington-Keokuk studies and on our diagenetic studies of other strata. Recent research on Burlington-Keokuk rocks include development and application of boron isotopes and the U--Th--Pb system to dolomite studies, investigations of porosity and permeability in the dolostones. Projects on other strata include dolomitization and limestones diagenesis of Devonian carbonates of Alberta and Western Australia, Miocene reefal carbonates of Spain, Neogene carbonates of Curacao and Bonaire, Waulsortian limestones of Ireland, modelling of trace elements and stable isotopes, and experimental growth of calcites to investigate crystallographic controls of trace element incorporation.

Functionalized carbon nanotubes for potential medicinal applications.

PubMed

Zhang, Yi; Bai, Yuhong; Yan, Bing

2010-06-01

Functionalized carbon nanotubes display unique properties that enable a variety of medicinal applications, including the diagnosis and treatment of cancer, infectious diseases and central nervous system disorders, and applications in tissue engineering. These potential applications are particularly encouraged by their ability to penetrate biological membranes and relatively low toxicity. High aspect ratio, unique optical property and the likeness as small molecule make carbon nanotubes an unusual allotrope of element carbon. After functionalization, carbon nanotubes display potentials for a variety of medicinal applications, including the diagnosis and treatment of cancer, infectious diseases and central nervous system disorders, and applications in tissue engineering. These potential applications are particularly encouraged by their ability to penetrate biological membranes and relatively low toxicity. (c) 2010 Elsevier Ltd. All rights reserved.

CHEMICAL CHARACTERIZATION OF AMBIENT PARTICULATE MATTER NEAR THE WORLD TRADE CENTER: ELEMENTAL CARBON, ORGANIC CARBON, AND MASS RECONSTRUCTION

EPA Science Inventory

Concentrations of elemental carbon (EC), organic carbon matter (OM), particulate matter less than 2.5 um (PM2.5), and reconstructed soil, trace element oxides, and sulfate are reported from four locations near the World Trade Center (WTC) complex for airborne particulate matter (...

Electrocatalytic process for carbon dioxide conversion

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

Masel, Richard I.; Salehi-Khojin, Amin; Kutz, Robert

An electrocatalytic process for carbon dioxide conversion includes combining a Catalytically Active Element and a Helper Polymer in the presence of carbon dioxide, allowing a reaction to proceed to produce a reaction product, and applying electrical energy to said reaction to achieve electrochemical conversion of said carbon dioxide reactant to said reaction product. The Catalytically Active Element can be a metal in the form of supported or unsupported particles or flakes with an average size between 0.6 nm and 100 nm. The reaction products comprise at least one of CO, HCO.sup.-, H.sub.2CO, (HCO.sub.2).sup.-, H.sub.2CO.sub.2, CH.sub.3OH, CH.sub.4, C.sub.2H.sub.4, CH.sub.3CH.sub.2OH, CH.sub.3COO.sup.-, CH.sub.3COOH,more » C.sub.2H.sub.6, (COOH).sub.2, (COO.sup.-).sub.2, and CF.sub.3COOH.« less

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

Young, B.C.; Musich, M.A.

A fixed-bed reactor system with continuous Hg{sup 0} analysis capabilities was used to evaluate commercial carbon sorbents for the removal of elemental mercury from simulated flue gas. The objectives of the program were to compare the sorbent effectiveness under identical test conditions and to identify the effects of various flue gas components on elemental mercury sorption. Sorbents tested included steam-activated lignite, chemical-activated hardwood and bituminous coal, iodated steam-activated coconut shell, and sulfur-impregnated steam-activated bituminous coal. The iodated carbon was the most effective carbon, showing over 99% mercury removal according to EPA Method 101A. Data indicate that O{sub 2} (4 vol%)more » and SO{sub 2} (500 ppm) improved the mercury removal of the other carbons for tests at 150{degrees}C using 100 {mu}g/m{sup 3} Hg{sup 0}. Further, the presence of HCl (at 50 ppm) produced a magnitude increase in mercury removal for the steam-activated and sulfur-impregnated bituminous coal-based carbons.« less

Elemental carbon exposure at residence and survival after acute myocardial infarction.

PubMed

von Klot, Stephanie; Gryparis, Alexandros; Tonne, Cathryn; Yanosky, Jeffrey; Coull, Brent A; Goldberg, Robert J; Lessard, Darleen; Melly, Steven J; Suh, Helen H; Schwartz, Joel

2009-07-01

Particulate air pollution has been consistently related to cardiovascular mortality. Some evidence suggests that particulate matter may accelerate the atherosclerotic process. Effects of within-city variations of particulate air pollution on survival after an acute cardiovascular event have been little explored. We conducted a cohort study of hospital survivors of acute myocardial infarction (MI) from the Worcester, MA, metropolitan area to investigate the long-term effects of within-city variation in traffic-related air pollution on mortality. The study builds on an ongoing community-wide investigation examining changes over time in MI incidence and case-fatality rates. We included confirmed cases of MI in 1995, 1997, 1999, 2001, and 2003. Long-term survival status was ascertained through 2005. A validated spatiotemporal land use regression model for traffic-related air pollution was developed and annual averages of elemental carbon at residence estimated. The effect of estimated elemental carbon on the long-term mortality of patients discharged after MI was analyzed using a Cox proportional hazards model, controlling for a variety of demographic, medical history, and clinical variables. Of the 3895 patients with validated MI, 44% died during follow-up. Exposure to estimated elemental carbon in the year of entry into the study was 0.44 microg/m on average. All-cause mortality increased by 15% (95% confidence interval = 0.03%-29%) per interquartile range increase in estimated yearly elemental carbon (0.24 microg/m) after the second year of survival. No association between traffic-related pollution and all-cause mortality was observed during the first 2 years of follow-up. Chronic traffic-related particulate air pollution is associated with increased mortality in hospital survivors of acute MI after the second year of survival.

METHOD OF FORMING A FUEL ELEMENT FOR A NUCLEAR REACTOR

DOEpatents

Layer, E.H. Jr.; Peet, C.S.

1962-01-23

A method is given for preparing a fuel element for a nuclear reactor. The method includes the steps of sandblasting a body of uranium dioxide to roughen the surface thereof, depositing a thin layer of carbon thereon by thermal decomposition of methane, and cladding the uranium dioxide body with zirconium by gas pressure bonding. (AEC)

Study of different concentric rings inside gallstones with LIBS.

PubMed

Pathak, Ashok Kumar; Singh, Vivek Kumar; Rai, Nilesh Kumar; Rai, Awadhesh Kumar; Rai, Pradeep Kumar; Rai, Pramod Kumar; Rai, Suman; Baruah, G D

2011-07-01

Gallstones obtained from patients from the north-east region of India (Assam) were studied using laser-induced breakdown spectroscopy (LIBS) technique. LIBS spectra of the different layers (in cross-section) of the gallstones were recorded in the spectral region 200-900 nm. Several elements, including calcium, magnesium, manganese, copper, silicon, phosphorus, iron, sodium and potassium, were detected in the gallstones. Lighter elements, including carbon, hydrogen, nitrogen and oxygen were also detected, which demonstrates the superiority of the LIBS technique over other existing analytical techniques. The LIBS technique was applied to investigate the evolution of C(2) swan bands and CN violet bands in the LIBS spectra of the gallstones in air and an argon atmosphere. The different layers (dark and light layers) of the gallstones were discriminated on the basis of the presence and intensities of the spectral lines for carbon, hydrogen, nitrogen, oxygen and copper. An attempt was also made to correlate the presence of major and minor elements in the gallstones with the common diet of the population of Assam.

Impact of Elevated CO2 on Trace Element Release from Aquifer Sediments of the San Joaquin Valley, CA

NASA Astrophysics Data System (ADS)

Fox, P. M.; Nico, P. S.; Davis, J. A.; Spycher, N.

2014-12-01

Carbon capture and storage (CCS) is a promising technique for mitigating climate change by storing large volumes of carbon dioxide in deep saline aquifers. In California, the thick marine sediments of the Central and Salinas Valleys have been identified as prime targets for future CO2 storage. However, the potential impacts on water quality of overlying drinking-water aquifers must be studied before CCS can be implemented. In this study, we compare trace element release from San Joaquin Valley aquifer sediments with a wide range of textural and redox properties. Kinetic batch experiments were performed with artificial groundwater continuously equilibrated under CO2-saturated (at 1 atm) and background CO2 (0.002-0.006 atm) conditions, resulting in a shift of nearly 3 pH units. In addition, the reversibility of trace element release was studied by sequentially lowering the CO2 from 1.0 atm to 0.5 atm to background concentrations (0.002-0.006 atm) for CO2-saturated systems in order to mimic the dissipation of a CO2 plume in the aquifer. During exposure to high CO2, a number of elements displayed enhanced release compared to background CO2 experiments (Ca, Mg, Li, Si, B, As, Sr, Ni, Fe, Mn, V, Ti, and Co) with concentrations of As, Fe, and Mn exceeding EPA maximum contaminant levels in some cases. On the other hand, Mo and U showed suppressed release. Most intriguing, many of the elements showing enhanced release displayed at least some degree of irreversibility when CO2 concentrations were decreased to background levels. In fact, in some cases (i.e., for V), an element showed further release when CO2 concentrations were decreased. These results suggest that there may be longer-term effects on groundwater quality that persist even after the CO2 plume has dissipated. Several different mechanisms of trace element release including ion exchange, desorption, and carbonate mineral dissolution are explored. Preliminary modeling results suggest that carbonate mineral dissolution can play a key role in driving trace element release even in sediments where carbonates are in low abundance.

Stages of weathering mantle formation from carbonate rocks in the light of rare earth elements (REE) and Sr-Nd-Pb isotopes

NASA Astrophysics Data System (ADS)

Hissler, Christophe; Stille, Peter

2015-04-01

Weathering mantles are widespread and include lateritic, sandy and kaolinite-rich saprolites and residuals of partially dissolved rocks. These old regolith systems have a complex history of formation and may present a polycyclic evolution due to successive geological and pedogenetic processes that affected the profile. Until now, only few studies highlighted the unusual high content of associated trace elements in weathering mantles originating from carbonate rocks, which have been poorly studied, compared to those developing on magmatic bedrocks. For instance, these enrichments can be up to five times the content of the underlying carbonate rocks. However, these studies also showed that the carbonate bedrock content only partially explains the soil enrichment for all the considered major and trace elements. Up to now, neither soil, nor saprolite formation has to our knowledge been geochemically elucidated. Therefore, the aim of this study was to examine more closely the soil forming dynamics and the relationship of the chemical soil composition to potential sources. REE distribution patterns and Sr-Nd-Pb isotope ratios have been used because they are particularly well suited to identify trace element migration, to recognize origin and mixing processes and, in addition, to decipher possible anthropogenic and/or "natural" atmosphere-derived contributions to the soil. Moreover, leaching experiments have been applied to identify mobile phases in the soil system and to yield information on the stability of trace elements and especially on their behaviour in these Fe-enriched carbonate systems. All these geochemical informations indicate that the cambisol developing on such a typical weathering mantle ("terra fusca") has been formed through weathering of a condensed Bajocian limestone-marl facies. This facies shows compared to average world carbonates important trace element enrichments. Their trace element distribution patterns are similar to those of the soil suggesting their close genetic relationships. Sr-Nd-Pb isotope data allow to identify four principal components in the soil: a silicate-rich pool at close to the surface, a leachable REE enriched pool at the bottom of the soil profile, the limestone facies on which the weathering profile developed and an anthropogenic, atmosphere-derived component detected in the soil leachates of the uppermost soil horizon. The leachable phases are mainly secondary carbonate-bearing REE phases such as bastnaesite. The isotope data and trace element distribution patterns indicate that at least four geological and environmental events impacted the chemical and isotopical compositions of the soil system since the Cretaceous.

Finite Element Analysis of Particle Ionization within Carbon Nanotube Ion Micro Thruster

DTIC Science & Technology

2017-12-01

NAVAL POSTGRADUATE SCHOOL MONTEREY, CALIFORNIA THESIS Approved for public release. Distribution is unlimited. FINITE ELEMENT ...AND DATES COVERED Master’s thesis 4. TITLE AND SUBTITLE FINITE ELEMENT ANALYSIS OF PARTICLE IONIZATION WITHIN CARBON NANOTUBE ION MICRO THRUSTER 5...simulation, carbon nanotube simulation, microsatellite, finite element analysis, electric field, particle tracing 15. NUMBER OF PAGES 55 16. PRICE

Geochemistry and origin of regional dolomites

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

Hanson, G.N.; Meyers, W.J.

1989-12-01

The major goal of the carbonate research program at Stony Brook is to better understand the conditions and processes leading to regional diagenesis of carbonate rocks. Our research focuses on studies of ancient, massive dolostones, but we are also studying limestone diagenesis for its own importance, and as it relates to dolomitization. Our approach has been to carry out a very detailed petrographic and geochemical case study to the Mississippian Burlington-Keokuk Fms. of Iowa, Illinois and Missouri, and to develop this as a testing ground for new geochemical and modelling techniques, and for testing various models for regional dolomitization inmore » epicontinental carbonates. The ideas and techniques developed in our Burlington-Keokuk studies are being expanded and applied to carbonate sequences of other ages (Devonian to Neogene), and other tectono-sedimentary settings. The emphasis of this report will be on new developments and results on the Burlington-Keokuk studies and on our diagenetic studies of other strata. Recent research on Burlington-Keokuk rocks include development and application of boron isotopes and the U--Th--Pb system to dolomite studies, investigations of porosity and permeability in the dolostones. Projects on other strata include dolomitization and limestones diagenesis of Devonian carbonates of Alberta and Western Australia, Miocene reefal carbonates of Spain, Neogene carbonates of Curacao and Bonaire, Waulsortian limestones of Ireland, modelling of trace elements and stable isotopes, and experimental growth of calcites to investigate crystallographic controls of trace element incorporation. 118 refs., 46 figs.« less

Treatment of organic waste

DOEpatents

Grantham, LeRoy F.

1979-01-01

An organic waste containing at least one element selected from the group consisting of strontium, cesium, iodine and ruthenium is treated to achieve a substantial reduction in the volume of the waste and provide for fixation of the selected element in an inert salt. The method of treatment comprises introducing the organic waste and a source of oxygen into a molten salt bath maintained at an elevated temperature to produce solid and gaseous reaction products. The gaseous reaction products comprise carbon dioxide and water vapor, and the solid reaction products comprise the inorganic ash constituents of the organic waste and the selected element which is retained in the molten salt. The molten salt bath comprises one or more alkali metal carbonates, and may optionally include from 1 to about 25 wt.% of an alkali metal sulfate.

Characterization of chemical and particulate emissions from aircraft engines

NASA Astrophysics Data System (ADS)

Agrawal, Harshit; Sawant, Aniket A.; Jansen, Karel; Wayne Miller, J.; Cocker, David R.

2008-06-01

This paper presents a series of measurements from four on-wing, commercial aircraft engines, including two newer CFM56-7 engines and two earlier CFM56-3 engines. Samples were collected from each engine using a probe positioned behind the exhaust nozzle of the aircraft, chocked on a concrete testing pad. The emission factors for particulate matter mass, elemental and organic carbon, carbonyls, polycyclic aromatic hydrocarbons, n-alkanes, dioxins, metals and ions are reported for four different engine power setting modes. The emissions indices of particulate matter, elemental and organic carbon are highly power dependent for these engines. Particulate matter emission indices (g kg-1 fuel) are found to increase from 1.1E-02 to 2.05E-01 with increase in power from idle to 85%. The elemental carbon to organic carbon varies from 0.5 to 3.8 with change in power from idle to 85%. The carbonyl emissions are dominated by formaldehyde. The emission index of formaldehyde ranges from 2.3E-01 to 4.8E-01 g kg-1 fuel. The distribution of metals depends on the difference in the various engines. The dioxin emissions from the aircraft engines are observed to be below detection limit.

Strength and deformability of compressed concrete elements with various types of non-metallic fiber and rods reinforcement under static loading

NASA Astrophysics Data System (ADS)

Nevskii, A. V.; Baldin, I. V.; Kudyakov, K. L.

2015-01-01

Adoption of modern building materials based on non-metallic fibers and their application in concrete structures represent one of the important issues in construction industry. This paper presents results of investigation of several types of raw materials selected: basalt fiber, carbon fiber and composite fiber rods based on glass and carbon. Preliminary testing has shown the possibility of raw materials to be effectively used in compressed concrete elements. Experimental program to define strength and deformability of compressed concrete elements with non-metallic fiber reinforcement and rod composite reinforcement included design, manufacture and testing of several types of concrete samples with different types of fiber and longitudinal rod reinforcement. The samples were tested under compressive static load. The results demonstrated that fiber reinforcement of concrete allows increasing carrying capacity of compressed concrete elements and reducing their deformability. Using composite longitudinal reinforcement instead of steel longitudinal reinforcement in compressed concrete elements insignificantly influences bearing capacity. Combined use of composite rod reinforcement and fiber reinforcement in compressed concrete elements enables to achieve maximum strength and minimum deformability.

SORPTION OF ELEMENTAL MERCURY BY ACTIVATED CARBONS

EPA Science Inventory

The mechanisms and rate of elemental mercury (HgO) capture by activated carbons have been studied using a bench-scale apparatus. Three types of activated carbons, two of which are thermally activated (PC-100 and FGD) and one with elemental sulfur (S) impregnated in it (HGR), were...

Origin and migration of trace elements in the surface sediments of Majuro Atoll, Marshall Islands.

PubMed

Ito, Lisa; Omori, Takayuki; Yoneda, Minoru; Yamaguchi, Toru; Kobayashi, Ryuta; Takahashi, Yoshio

2018-07-01

The sediments of Majuro Atoll, Marshall Islands, consist of bioclastic materials, including foraminifera and coral debris. The sedimentary depth profiles of elements showed that various elements including zinc (Zn) and copper (Cu) were enriched in the upper layers of the islands of Majuro Atoll. Carbon-14 dating revealed that the sedimentation of the upper layer was completed before 1670 and 542 cal BP in Laura and Calalen, respectively. The enriched elements could be categorized by their origins: (a) terrestrial elements transported as dust (aluminum (Al) and rare earth elements (REEs)); (b) anthropogenic elements (Zn and Cu); and (c) elements supplied by seabirds (phosphorus (P)). From the results of the total amount of Al supplied to sediments for ca. 2000 years, Al in Majuro Atoll was suggested to be airborne origin. The enrichment factors of the elements normalized to Al concentration of continental crust showed that REEs were also transported as dust, while Zn and Cu were mainly of anthropogenic origin. The speciation analysis by X-ray absorption near-edge structure (XANES) showed the presence of Zn-Cu alloys originated from industrial products. It was also revealed that Zn was enriched in the surface due to anthropogenic emission after urbanization on Majuro Atoll and fixed by carbonate and phosphate at the upper layer, which inhibits migration of Zn into the deeper layer and its release to the groundwater and costal water. Hence, the fixation of heavy metals at the surface prevents their exposure to aquatic organisms and residents via fresh groundwater in the island. Copyright © 2018 Elsevier Ltd. All rights reserved.

Neutron-capture Nucleosynthesis in the First Stars

NASA Astrophysics Data System (ADS)

Roederer, Ian U.; Preston, George W.; Thompson, Ian B.; Shectman, Stephen A.; Sneden, Christopher

2014-04-01

Recent studies suggest that metal-poor stars enhanced in carbon but containing low levels of neutron-capture elements may have been among the first to incorporate the nucleosynthesis products of the first generation of stars. We have observed 16 stars with enhanced carbon or nitrogen using the MIKE Spectrograph on the Magellan Telescopes at Las Campanas Observatory and the Tull Spectrograph on the Smith Telescope at McDonald Observatory. We present radial velocities, stellar parameters, and detailed abundance patterns for these stars. Strontium, yttrium, zirconium, barium, europium, ytterbium, and other heavy elements are detected. In four stars, these heavy elements appear to have originated in some form of r-process nucleosynthesis. In one star, a partial s-process origin is possible. The origin of the heavy elements in the rest of the sample cannot be determined unambiguously. The presence of elements heavier than the iron group offers further evidence that zero-metallicity rapidly rotating massive stars and pair instability supernovae did not contribute substantial amounts of neutron-capture elements to the regions where the stars in our sample formed. If the carbon- or nitrogen-enhanced metal-poor stars with low levels of neutron-capture elements were enriched by products of zero-metallicity supernovae only, then the presence of these heavy elements indicates that at least one form of neutron-capture reaction operated in some of the first stars. This paper includes data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile, and The McDonald Observatory of The University of Texas at Austin.

Calculation of residual principal stresses in CVD boron on carbon filaments

NASA Technical Reports Server (NTRS)

Behrendt, D. R.

1980-01-01

A three-dimensional finite element model of the chemical vapor deposition of boron on a carbon substrate (B/C) is developed. The model includes an expansion of the boron after deposition due to atomic rearrangement and includes creep of the boron and carbon. Curves are presented showing the variation of the principal residual stresses and the filament elongation with the parameters defining deposition strain and creep. The calculated results are compared with experimental axial residual stress and elongation measurements made on B/C filaments. For good agreement between calculated and experimental results, the deposited boron must continue to expand after deposition, and the build up of residual stresses must be limited by significant boron and carbon creep rates.

Carbon nanotube temperature and pressure sensors

DOEpatents

Ivanov, Ilia N.; Geohegan, David B.

2016-11-15

The present invention, in one embodiment, provides a method of measuring pressure or temperature using a sensor including a sensor element composed of a plurality of carbon nanotubes. In one example, the resistance of the plurality of carbon nanotubes is measured in response to the application of temperature or pressure. The changes in resistance are then recorded and correlated to temperature or pressure. In one embodiment, the present invention provides for independent measurement of pressure or temperature using the sensors disclosed herein.

Carbon nanotube temperature and pressure sensors

DOEpatents

Ivanov, Ilia N.; Geohegan, David B.

2016-12-13

The present invention, in one embodiment, provides a method of measuring pressure or temperature using a sensor including a sensor element composed of a plurality of carbon nanotubes. In one example, the resistance of the plurality of carbon nanotubes is measured in response to the application of temperature or pressure. The changes in resistance are then recorded and correlated to temperature or pressure. In one embodiment, the present invention provides for independent measurement of pressure or temperature using the sensors disclosed herein.

Carbon nanotube temperature and pressure sensors

DOEpatents

Ivanov, Ilia N; Geohegan, David Bruce

2013-10-29

The present invention, in one embodiment, provides a method of measuring pressure or temperature using a sensor including a sensor element composed of a plurality of carbon nanotubes. In one example, the resistance of the plurality of carbon nanotubes is measured in response to the application of temperature or pressure. The changes in resistance are then recorded and correlated to temperature or pressure. In one embodiment, the present invention provides for independent measurement of pressure or temperature using the sensors disclosed herein.

Carbon nanotube temperature and pressure sensors

DOEpatents

Ivanov, Ilia N.; Geohegan, David B.

2016-10-25

The present invention, in one embodiment, provides a method of measuring pressure or temperature using a sensor including a sensor element composed of a plurality of carbon nanotubes. In one example, the resistance of the plurality of carbon nanotubes is measured in response to the application of temperature or pressure. The changes in resistance are then recorded and correlated to temperature or pressure. In one embodiment, the present invention provides for independent measurement of pressure or temperature using the sensors disclosed herein.

Carbon nanotube temperature and pressure sensors

DOEpatents

Ivanov, Ilia N.; Geohegan, David B.

2017-09-12

The present invention, in one embodiment, provides a method of measuring pressure or temperature using a sensor including a sensor element composed of a plurality of carbon nanotubes. In one example, the resistance of the plurality of carbon nanotubes is measured in response to the application of temperature or pressure. The changes in resistance are then recorded and correlated to temperature or pressure. In one embodiment, the present invention provides for independent measurement of pressure or temperature using the sensors disclosed herein.

Carbon fiber reinforced thermoplastic composites for future automotive applications

NASA Astrophysics Data System (ADS)

Friedrich, K.

2016-05-01

After a brief introduction to polymer composite properties and markets, the state of the art activities in the field of manufacturing of advanced composites for automotive applications are elucidated. These include (a) long fiber reinforced thermoplastics (LFT) for secondary automotive components, and (b) continuous carbon fiber reinforced thermosetting composites for car body applications. It is followed by future possibilities of carbon fiber reinforced thermoplastic composites for e.g. (i) crash elements, (ii) racing car seats, and (iii) production and recycling of automotive fenders.

Solid State Carbon Monoxide Sensor

NASA Technical Reports Server (NTRS)

Upchurch, Billy T. (Inventor); Wood, George M. (Inventor); Schryer, David R. (Inventor); Leighty, Bradley D. (Inventor); Oglesby, Donald M. (Inventor); Kielin, Erik J. (Inventor); Brown, Kenneth G. (Inventor); DAmbrosia, Christine M. (Inventor)

1999-01-01

A means for detecting carbon monoxide which utilizes an un-heated catalytic material to oxidize carbon monoxide at ambient temperatures. Because this reaction is exothermic, a thermistor in contact with the catalytic material is used as a sensing element to detect the heat evolved as carbon monoxide is oxidized to carbon dioxide at the catalyst surface, without any heaters or external heating elements for the ambient air or catalytic element material. Upon comparison to a reference thermistor, relative increases in the temperature of the sensing thermistor correspond positively with an increased concentration of carbon monoxide in the ambient medium and are thus used as an indicator of the presence of carbon monoxide.

Multi-layer carbon-based coatings for field emission

DOEpatents

Sullivan, John P.; Friedmann, Thomas A.

1998-01-01

A multi-layer resistive carbon film field emitter device for cold cathode field emission applications. The multi-layered film of the present invention consists of at least two layers of a conductive carbon material, preferably amorphous-tetrahedrally coordinated carbon, where the resistivities of adjacent layers differ. For electron emission from the surface, the preferred structure can be a top layer having a lower resistivity than the bottom layer. For edge emitting structures, the preferred structure of the film can be a plurality of carbon layers, where adjacent layers have different resistivities. Through selection of deposition conditions, including the energy of the depositing carbon species, the presence or absence of certain elements such as H, N, inert gases or boron, carbon layers having desired resistivities can be produced.

Elemental economy: microbial strategies for optimizing growth in the face of nutrient limitation.

PubMed

Merchant, Sabeeha S; Helmann, John D

2012-01-01

Microorganisms play a dominant role in the biogeochemical cycling of nutrients. They are rightly praised for their facility for fixing both carbon and nitrogen into organic matter, and microbial driven processes have tangibly altered the chemical composition of the biosphere and its surrounding atmosphere. Despite their prodigious capacity for molecular transformations, microorganisms are powerless in the face of the immutability of the elements. Limitations for specific elements, either fleeting or persisting over eons, have left an indelible trace on microbial genomes, physiology, and their very atomic composition. We here review the impact of elemental limitation on microbes, with a focus on selected genetic model systems and representative microbes from the ocean ecosystem. Evolutionary adaptations that enhance growth in the face of persistent or recurrent elemental limitations are evident from genome and proteome analyses. These range from the extreme (such as dispensing with a requirement for a hard to obtain element) to the extremely subtle (changes in protein amino acid sequences that slightly, but significantly, reduce cellular carbon, nitrogen, or sulfur demand). One near-universal adaptation is the development of sophisticated acclimation programs by which cells adjust their chemical composition in response to a changing environment. When specific elements become limiting, acclimation typically begins with an increased commitment to acquisition and a concomitant mobilization of stored resources. If elemental limitation persists, the cell implements austerity measures including elemental sparing and elemental recycling. Insights into these fundamental cellular properties have emerged from studies at many different levels, including ecology, biological oceanography, biogeochemistry, molecular genetics, genomics, and microbial physiology. Here, we present a synthesis of these diverse studies and attempt to discern some overarching themes. Copyright © 2012 Elsevier Ltd. All rights reserved.

Elemental Economy: microbial strategies for optimizing growth in the face of nutrient limitation

PubMed Central

Merchant, Sabeeha S.; Helmann, John D.

2014-01-01

Microorganisms play a dominant role in the biogeochemical cycling of nutrients. They are rightly praised for their facility at fixing both carbon and nitrogen into organic matter, and microbial driven processes have tangibly altered the chemical composition of the biosphere and its surrounding atmosphere. Despite their prodigious capacity for molecular transformations, microorganisms are powerless in the face of the immutability of the elements. Limitations for specific elements, either fleeting or persisting over eons, have left an indelible trace on microbial genomes, physiology, and their very atomic composition. We here review the impact of elemental limitation on microbes, with a focus on selected genetic model systems and representative microbes from the ocean ecosystem. Evolutionary adaptations that enhance growth in the face of persistent or recurrent elemental limitations are evident from genome and proteome analyses. These range from the extreme (such as dispensing with a requirement for a hard to obtain element) to the extremely subtle (changes in protein amino acid sequences that slightly, but significantly, reduce cellular carbon, nitrogen, or sulfur demand). One near universal adaptation is the development of sophisticated acclimation programs by which cells adjust their chemical composition in response to a changing environment. When specific elements become limiting, acclimation typically begins with an increased commitment to acquisition and a concomitant mobilization of stored resources. If elemental limitation persists, the cell implements austerity measures including elemental-sparing and elemental-recycling. Insights into these fundamental cellular properties have emerged from studies at many different levels; including ecology, biological oceanography, biogeochemistry, molecular genetics, genomics, and microbial physiology. Here, we present a synthesis of these diverse studies and attempt to discern some overarching themes. PMID:22633059

Differences in the OC/EC Ratios that Characterize Ambient and Source Aerosols due to Thermal-Optical Analysis

EPA Science Inventory

Thermal-optical analysis (TOA) is typically used to measure the OC/EC (organic carbon/elemental carbon) and EC/TC (elemental carbon/total carbon) ratios in source and atmospheric aerosols. The present study utilizes a dual-optical carbon aerosol analyzer to examine the effects of...

Atomization methods for forming magnet powders

DOEpatents

Sellers, Charles H.; Branagan, Daniel J.; Hyde, Timothy A.

2000-01-01

The invention encompasses methods of utilizing atomization, methods for forming magnet powders, methods for forming magnets, and methods for forming bonded magnets. The invention further encompasses methods for simulating atomization conditions. In one aspect, the invention includes an atomization method for forming a magnet powder comprising: a) forming a melt comprising R.sub.2.1 Q.sub.13.9 B.sub.1, Z and X, wherein R is a rare earth element; X is an element selected from the group consisting of carbon, nitrogen, oxygen and mixtures thereof; Q is an element selected from the group consisting of Fe, Co and mixtures thereof; and Z is an element selected from the group consisting of Ti, Zr, Hf and mixtures thereof; b) atomizing the melt to form generally spherical alloy powder granules having an internal structure comprising at least one of a substantially amorphous phase or a substantially nanocrystalline phase; and c) heat treating the alloy powder to increase an energy product of the alloy powder; after the heat treatment, the alloy powder comprising an energy product of at least 10 MGOe. In another aspect, the invention includes a magnet comprising R, Q, B, Z and X, wherein R is a rare earth element; X is an element selected from the group consisting of carbon, nitrogen, oxygen and mixtures thereof; Q is an element selected from the group consisting of Fe, Co and mixtures thereof; and Z is an element selected from the group consisting of Ti, Zr, Hf and mixtures thereof; the magnet comprising an internal structure comprising R.sub.2.1 Q.sub.13.9 B.sub.1.

Sources and mobility of carbonate melts beneath cratons, with implications for deep carbon cycling, metasomatism and rift initiation

NASA Astrophysics Data System (ADS)

Tappe, Sebastian; Romer, Rolf L.; Stracke, Andreas; Steenfelt, Agnete; Smart, Katie A.; Muehlenbachs, Karlis; Torsvik, Trond H.

2017-05-01

Kimberlite and carbonatite magmas that intrude cratonic lithosphere are among the deepest probes of the terrestrial carbon cycle. Their co-existence on thick continental shields is commonly attributed to continuous partial melting sequences of carbonated peridotite at >150 km depths, possibly as deep as the mantle transition zone. At Tikiusaaq on the North Atlantic craton in West Greenland, approximately 160 Ma old ultrafresh kimberlite dykes and carbonatite sheets provide a rare opportunity to study the origin and evolution of carbonate-rich melts beneath cratons. Although their Sr-Nd-Hf-Pb-Li isotopic compositions suggest a common convecting upper mantle source that includes depleted and recycled oceanic crust components (e.g., negative ΔεHf coupled with > + 5 ‰ δ7Li), incompatible trace element modelling identifies only the kimberlites as near-primary low-degree partial melts (0.05-3%) of carbonated peridotite. In contrast, the trace element systematics of the carbonatites are difficult to reproduce by partial melting of carbonated peridotite, and the heavy carbon isotopic signatures (-3.6 to - 2.4 ‰ δ13C for carbonatites versus -5.7 to - 3.6 ‰ δ13C for kimberlites) require open-system fractionation at magmatic temperatures. Given that the oxidation state of Earth's mantle at >150 km depth is too reduced to enable larger volumes of 'pure' carbonate melt to migrate, it is reasonable to speculate that percolating near-solidus melts of carbonated peridotite must be silicate-dominated with only dilute carbonate contents, similar to the Tikiusaaq kimberlite compositions (e.g., 16-33 wt.% SiO2). This concept is supported by our findings from the North Atlantic craton where kimberlite and other deeply derived carbonated silicate melts, such as aillikites, exsolve their carbonate components within the shallow lithosphere en route to the Earth's surface, thereby producing carbonatite magmas. The relative abundances of trace elements of such highly differentiated 'cratonic carbonatites' have only little in common with those of metasomatic agents that act on the deeper lithosphere. Consequently, carbonatite trace element systematics should only be used with caution when constraining carbon mobility and metasomatism at mantle depths. Regardless of the exact nature of carbonate-bearing melts within the mantle lithosphere, they play an important role in enrichment processes, thereby decreasing the stability of buoyant cratons and promoting rift initiation - as exemplified by the Mesozoic-Cenozoic breakup of the North Atlantic craton.

Elemental Metals or Oxides Distributed on a Carbon Substrate or Self-Supported and the Manufacturing Process Using Graphite Oxide as Template

NASA Technical Reports Server (NTRS)

Hung, Ching-Chen (Inventor)

1999-01-01

A process for providing elemental metals or metal oxides distributed on a carbon substrate or self-supported utilizing graphite oxide as a percursor. The graphite oxide is exposed to one or more metal chlorides to form an intermediary product comprising carbon, metal, chloride, and oxygen. This intermediary product can be further processed by direct exposure to carbonate solutions to form a second intermediary product comprising carbon, metal carbonate, and oxygen. Either intermediary product may be further processed: a) in air to produce metal oxide; b) in an inert environment to produce metal oxide on carbon substrate; c) in a reducing environment to produce elemental metal distributed on carbon substrate. The product generally takes the shape of the carbon precursor.

Elemental Metals or Oxides Distributed on a Carbon Substrate or Self-Supported and the Manufacturing Process Using Graphite Oxide as Template

NASA Technical Reports Server (NTRS)

Hung, Ching-Cheh (Inventor)

1999-01-01

A process for providing elemental metals or metal oxides distributed on a carbon substrate or self-supported utilizing graphite oxide as a precursor. The graphite oxide is exposed to one or more metal chlorides to form an intermediary product comprising carbon, metal, chloride, and oxygen. This intermediary product can be further processed by direct exposure to carbonate-solutions to form a second intermediary product comprising carbon, metal carbonate, and oxygen. Either intermediary product may be further processed: a) in air to produce metal oxide; b) in an inert environment to produce metal oxide on carbon substrate; c) in a reducing environment to produce elemental metal distributed on carbon substrate. The product generally takes the shape of the carbon precursor.

The LysR-type transcription factor PacR is a global regulator of photosynthetic carbon assimilation in Anabaena.

PubMed

Picossi, Silvia; Flores, Enrique; Herrero, Antonia

2015-09-01

Cyanobacteria perform water-splitting photosynthesis and are important primary producers impacting the carbon and nitrogen cycles at global scale. They fix CO2 through ribulose-bisphosphate carboxylase/oxygenase (RuBisCo) and have evolved a distinct CO2 concentrating mechanism (CCM) that builds high CO2 concentrations in the vicinity of RuBisCo favouring its carboxylase activity. Filamentous cyanobacteria such as Anabaena fix CO2 in photosynthetic vegetative cells, which donate photosynthate to heterocysts that rely on a heterotrophic metabolism to fix N2 . CCM elements are induced in response to inorganic carbon limitation, a cue that exposes the photosynthetic apparatus to photodamage by over-reduction. An Anabaena mutant lacking the LysR-type transcription factor All3953 grew poorly and dies under high light. The rbcL operon encoding RuBisCo was induced upon carbon limitation in the wild type but not in the mutant. ChIP-Seq analysis was used to globally identify All3953 targets under carbon limitation. Targets include, besides rbcL, genes encoding CCM elements, photorespiratory pathway- photosystem- and electron transport-related components, and factors, including flavodiiron proteins, with a demonstrated or putative function in photoprotection. Quantitative reverse transcription polymerase chain reaction analysis of selected All3953 targets showed regulation in the wild type but not in the mutant. All3953 (PacR) is a global regulator of carbon assimilation in an oxygenic photoautotroph. © 2015 Society for Applied Microbiology and John Wiley & Sons Ltd.

Catalytic Graphitization of Coal-Based Carbon Materials with Light Rare Earth Elements.

PubMed

Wang, Rongyan; Lu, Guimin; Qiao, Wenming; Yu, Jianguo

2016-08-30

The catalytic graphitization mechanism of coal-based carbon materials with light rare earth elements was investigated using X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, selected-area electron diffraction, and high-resolution transmission electron microscopy. The interface between light rare earth elements and carbon materials was carefully observed, and two routes of rare earth elements catalyzing the carbon materials were found: dissolution-precipitation and carbide formation-decomposition. These two simultaneous processes certainly accelerate the catalytic graphitization of carbon materials, and light rare earth elements exert significant influence on the microstructure and thermal conductivity of graphite. Moreover, by virtue of praseodymium (Pr), it was found that a highly crystallographic orientation of graphite was induced and formed, which was reasonably attributed to the similar arrangements of the planes perpendicular to (001) in both graphite and Pr crystals. The interface between Pr and carbon was found to be an important factor for the orientation of graphite structure.

Addition of granular activated carbon and trace elements to favor volatile fatty acid consumption during anaerobic digestion of food waste.

PubMed

Capson-Tojo, Gabriel; Moscoviz, Roman; Ruiz, Diane; Santa-Catalina, Gaëlle; Trably, Eric; Rouez, Maxime; Crest, Marion; Steyer, Jean-Philippe; Bernet, Nicolas; Delgenès, Jean-Philippe; Escudié, Renaud

2018-07-01

The effect of supplementing granular activated carbon and trace elements on the anaerobic digestion performance of consecutive batch reactors treating food waste was investigated. The results from the first batch suggest that addition of activated carbon favored biomass acclimation, improving acetic acid consumption and enhancing methane production. Adding trace elements allowed a faster consumption of propionic acid. A second batch proved that a synergy existed when activated carbon and trace elements were supplemented simultaneously. The degradation kinetics of propionate oxidation were particularly improved, reducing significantly the batch duration and improving the average methane productivities. Addition of activated carbon favored the growth of archaea and syntrophic bacteria, suggesting that interactions between these microorganisms were enhanced. Interestingly, microbial analyses showed that hydrogenotrophic methanogens were predominant. This study shows for the first time that addition of granular activated carbon and trace elements may be a feasible solution to stabilize food waste anaerobic digestion. Copyright © 2018 Elsevier Ltd. All rights reserved.

Evolution of the atomic order and valence state of rare-earth atoms and uranium in a new carbon-metal composite—diphthalocyanine pyrolysate C64H32N16 Me ( Me = Y, La, Ce, Eu, and U)

NASA Astrophysics Data System (ADS)

Sovestnov, A. E.; Kapustin, V. K.; Tikhonov, V. I.; Fomin, E. V.; Chernenkov, Yu. P.

2014-08-01

The structure of a metal-carbon composite formed by the pyrolysis of diphthalocyanine of some rare-earth elements (Y, La, Ce, Eu) and uranium in the temperature range T ann = 800-1700°C has been investigated for the first time by the methods of X-ray diffraction analysis and X-ray line shift. It has been shown that, in the general case, the studied pyrolysates consist of three phases. One phase corresponds to the structure of graphite. The second phase corresponds to nitrides, carbides, and oxides of basic metal elements with a crystallite size ranging from 5 to 100 nm. The third phase is amorphous or consisting of crystallites with a size of ˜1 nm. It has been found that all the basic elements (Y, La, Ce, Eu, U) and incorporated iodine atoms in the third phase are in a chemically bound state. The previously unobserved electronic configurations have been revealed for europium. The possibility of including not only atoms of elements forming diphthalocyanine but also other elements (for example, iodine) in the composite structure is of interest, in particular, for the creation of a thermally, chemically, and radiation resistant metal-carbon matrix for the radioactive waste storage.

Calculation of residual principal stresses in CVD boron on carbon filaments

NASA Technical Reports Server (NTRS)

Behrendt, D. R.

1980-01-01

A three-dimensional finite element model of the chemical vapor deposition (CVD) of boron on a carbon substrate (B/C) is developed. The model includes an expansion of the boron after deposition due to atomic rearrangement and includes creep of the boron and carbon. Curves are presented to show how the principal residual stresses and the filament elongation vary as the parameters defining deposition strain and creep are varied. The calculated results are compared with experimental axial residual stress and elongation measurements made on B/C filaments. This comparison requires that for good agreement between calculated and experimental results, the deposited boron must continue to expand after deposition, and that the build-up of residual stresses is limited by significant boron and carbon creep rates.

Leaching modelling of slurry-phase carbonated steel slag.

PubMed

Costa, G; Polettini, A; Pomi, R; Stramazzo, A

2016-01-25

In the present work the influence of accelerated mineral carbonation on the leaching behaviour of basic oxygen furnace steel slag was investigated. The environmental behaviour of the material as evaluated through the release of major elements and toxic metals under varying pH conditions was the main focus of the study. Geochemical modelling of the eluates was used to derive a theoretical description of the underlying leaching phenomena for the carbonated material as compared to the original slag. Among the investigated elements, Ca and Si were most appreciably affected by carbonation. A very clear effect of carbonation on leaching was observed for silicate phases, and lower-Ca/Si-ratio minerals were found to control leaching in carbonated slag eluates as compared to the corresponding untreated slag sample as a result of Ca depletion from the residual slag particles. Clear evidence was also gained of solubility control for Ca, Mg and Mn by a number of carbonate minerals, indicating a significant involvement of the original slag constituents in the carbonation process. The release of toxic metals (Zn, V, Cr, Mo) was found to be variously affected by carbonation, owing to different mechanisms including pH changes, dissolution/precipitation of carbonates as well as sorption onto reactive mineral surfaces. The leaching test results were used to derive further considerations on the expected metal release levels on the basis of specific assumptions on the relevant pH domains for the untreated and carbonated slag. Copyright © 2015 Elsevier B.V. All rights reserved.

A Review on Strengthening Steel Beams Using FRP under Fatigue

PubMed Central

Jumaat, Mohd Zamin; Ramli Sulong, N. H.

2014-01-01

In recent decades, the application of fibre-reinforced polymer (FRP) composites for strengthening structural elements has become an efficient option to meet the increased cyclic loads or repair due to corrosion or fatigue cracking. Hence, the objective of this study is to explore the existing FRP reinforcing techniques to care for fatigue damaged structural steel elements. This study covers the surface treatment techniques, adhesive curing, and support conditions under cyclic loading including fatigue performance, crack propagation, and failure modes with finite element (FE) simulation of the steel bridge girders and structural elements. FRP strengthening composites delay initial cracking, reduce the crack growth rate, extend the fatigue life, and decrease the stiffness decay with residual deflection. Prestressed carbon fibre-reinforced polymer (CFRP) is the best strengthening option. End anchorage prevents debonding of the CRRP strips at the beam ends by reducing the local interfacial shear and peel stresses. Hybrid-joint, nanoadhesive, and carbon-flex can also be attractive for strengthening systems. PMID:25243221

A review on strengthening steel beams using FRP under fatigue.

PubMed

Kamruzzaman, Mohamed; Jumaat, Mohd Zamin; Sulong, N H Ramli; Islam, A B M Saiful

2014-01-01

In recent decades, the application of fibre-reinforced polymer (FRP) composites for strengthening structural elements has become an efficient option to meet the increased cyclic loads or repair due to corrosion or fatigue cracking. Hence, the objective of this study is to explore the existing FRP reinforcing techniques to care for fatigue damaged structural steel elements. This study covers the surface treatment techniques, adhesive curing, and support conditions under cyclic loading including fatigue performance, crack propagation, and failure modes with finite element (FE) simulation of the steel bridge girders and structural elements. FRP strengthening composites delay initial cracking, reduce the crack growth rate, extend the fatigue life, and decrease the stiffness decay with residual deflection. Prestressed carbon fibre-reinforced polymer (CFRP) is the best strengthening option. End anchorage prevents debonding of the CRRP strips at the beam ends by reducing the local interfacial shear and peel stresses. Hybrid-joint, nanoadhesive, and carbon-flex can also be attractive for strengthening systems.

Simulated In Situ Determination of Soil Profile Organic and Inorganic Carbon With LIBS and VisNIR

NASA Astrophysics Data System (ADS)

Bricklemyer, R. S.; Brown, D. J.; Clegg, S. M.; Barefield, J. E.

2008-12-01

There is growing need for rapid, accurate, and inexpensive methods to measure, and verify soil organic carbon (SOC) change for national greenhouse gas accounting and the development of a soil carbon trading market. Laser Induced Breakdown Spectroscopy (LIBS) and Visible and Near Infrared Spectroscopy (VisNIR) are complementary analytical techniques that have the potential to fill that need. The LIBS method provides precise elemental analysis of soils, but generally cannot distinguish between organic C and inorganic C. VisNIR has been established as a viable technique for measuring soil properties including SOC and inorganic carbon (IC). As part of the Big Sky Carbon Sequestration Regional Partnership, 240 intact core samples (3.8 x 50 cm) have been collected from six agricultural fields in north central Montana, USA. Each of these core samples were probed concurrently with LIBS and VisNIR at 2.5, 7.5, 12.5, 17.5, 22.5, 27.5, 35 and 45 cm (+/- 1.5 cm) depths. VisNIR measurements were taken using an Analytical Spectral Devices (ASD, Boulder, CO, USA) Agrispec spectrometer to determine the partition of SOC vs. IC in the samples. The LIBS scans were collected with the LANL LIBS Core Scanner Instrument which collected the entire 200 - 900 nm plasma emission including the 247.8 nm carbon emission line. This instrument also collected the emission from the elements typically found in inorganic carbon (Ca and Mg) and organic carbon (H, O, and N). Subsamples of soil (~ 4 g) were taken from interrogation points for laboratory determination of SOC and IC. Using this analytical data, we constructed several full spectrum multivariate VisNIR/LIBS calibration models for SOC and IC. These models were then applied to independent validation cores for model evaluation.

Simulations of carbon fiber composite delamination tests

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

Kay, G

2007-10-25

Simulations of mode I interlaminar fracture toughness tests of a carbon-reinforced composite material (BMS 8-212) were conducted with LSDYNA. The fracture toughness tests were performed by U.C. Berkeley. The simulations were performed to investigate the validity and practicality of employing decohesive elements to represent interlaminar bond failures that are prevalent in carbon-fiber composite structure penetration events. The simulations employed a decohesive element formulation that was verified on a simple two element model before being employed to perform the full model simulations. Care was required during the simulations to ensure that the explicit time integration of LSDYNA duplicate the near steady-statemore » testing conditions. In general, this study validated the use of employing decohesive elements to represent the interlaminar bond failures seen in carbon-fiber composite structures, but the practicality of employing the elements to represent the bond failures seen in carbon-fiber composite structures during penetration events was not established.« less

Ferrous Analysis.

ERIC Educational Resources Information Center

Straub, William A.

1989-01-01

Elements covered in this review include: aluminum, antimony, arsenic, bismuth, boron, calcium, carbon, chromium, cobalt, copper, hydrogen, iron, lead, magnesium, manganese, molybdenum, nickel, niobium, nitrogen, oxygen, phosphorus, platinum, rare earths, silicons, sulfur, tin, titanium, tungsten, vanadium, zinc, and zirconium. Analytical methods…

Chemistry Notes.

ERIC Educational Resources Information Center

School Science Review, 1982

1982-01-01

Presents background information, laboratory procedures, classroom materials/activities, and experiments for chemistry. Topics include superheavy elements, polarizing power and chemistry of alkali metals, particulate carbon from combustion, tips for the chemistry laboratory, interesting/colorful experiments, behavior of bismuth (III) iodine, and…

Accuracy and Precision in Measurements of Biomass Oxidative Ratio and Carbon Oxidation State

NASA Astrophysics Data System (ADS)

Gallagher, M. E.; Masiello, C. A.; Randerson, J. T.; Chadwick, O. A.; Robertson, G. P.

2007-12-01

Ecosystem oxidative ratio (OR) is a critical parameter in the apportionment of anthropogenic CO2 between the terrestrial biosphere and ocean carbon reservoirs. OR is the ratio of O2 to CO2 in gas exchange fluxes between the terrestrial biosphere and atmosphere. Ecosystem OR is linearly related to biomass carbon oxidation state (Cox), a fundamental property of the earth system describing the bonding environment of carbon in molecules. Cox can range from -4 to +4 (CH4 to CO2). Variations in both Cox and OR are driven by photosynthesis, respiration, and decomposition. We are developing several techniques to accurately measure variations in ecosystem Cox and OR; these include elemental analysis, bomb calorimetry, and 13C nuclear magnetic resonance spectroscopy. A previous study, comparing the accuracy and precision of elemental analysis versus bomb calorimetry for pure chemicals, showed that elemental analysis-based measurements are more accurate, while calorimetry- based measurements yield more precise data. However, the limited biochemical range of natural samples makes it possible that calorimetry may ultimately prove most accurate, as well as most cost-effective. Here we examine more closely the accuracy of Cox and OR values generated by calorimetry on a large set of natural biomass samples collected from the Kellogg Biological Station-Long Term Ecological Research (KBS-LTER) site in Michigan.

Trace elements and REE geochemistry of Middle Devonian carbonate mounds (Maïder Basin, Eastern Anti-Atlas, Morocco): Implications for early diagenetic processes

NASA Astrophysics Data System (ADS)

Franchi, Fulvio; Turetta, Clara; Cavalazzi, Barbara; Corami, Fabiana; Barbieri, Roberto

2016-08-01

Trace and rare earth elements (REEs) have proven their utility as tools for assessing the genesis and early diagenesis of widespread geological bodies such as carbonate mounds, whose genetic processes are not yet fully understood. Carbonates from the Middle Devonian conical mud mounds of the Maïder Basin (eastern Anti-Atlas, Morocco) have been analysed for their REE and trace element distribution. Collectively, the carbonates from the Maïder Basin mud mounds appear to display coherent REE patterns. Three different geochemical patterns, possibly related with three different diagenetic events, include: i) dyke fills with a normal marine REE pattern probably precipitated in equilibrium with seawater, ii) mound micrite with a particular enrichment of overall REE contents and variable Ce anomaly probably related to variation of pH, increase of alkalinity or dissolution/remineralization of organic matter during early diagenesis, and iii) haematite-rich vein fills precipitated from venting fluids of probable hydrothermal origin. Our results reinforce the hypothesis that these mounds were probably affected by an early diagenesis induced by microbial activity and triggered by abundance of dispersed organic matter, whilst venting may have affected the mounds during a later diagenetic phase.

Multi-layer carbon-based coatings for field emission

DOEpatents

Sullivan, J.P.; Friedmann, T.A.

1998-10-13

A multi-layer resistive carbon film field emitter device for cold cathode field emission applications is disclosed. The multi-layered film of the present invention consists of at least two layers of a conductive carbon material, preferably amorphous-tetrahedrally coordinated carbon, where the resistivities of adjacent layers differ. For electron emission from the surface, the preferred structure can be a top layer having a lower resistivity than the bottom layer. For edge emitting structures, the preferred structure of the film can be a plurality of carbon layers, where adjacent layers have different resistivities. Through selection of deposition conditions, including the energy of the depositing carbon species, the presence or absence of certain elements such as H, N, inert gases or boron, carbon layers having desired resistivities can be produced. 8 figs.

Soil properties, strontium isotopic signatures and multi-element profiles to authenticate the origin of vegetables from small-scale regions: illustration with early potatoes from southern Italy.

PubMed

Zampella, Mariavittoria; Quétel, Christophe R; Paredes, Eduardo; Goitom Asfaha, Daniel; Vingiani, Simona; Adamo, Paola

2011-10-15

We propose a method for the authentication of the origin of vegetables grown under similar weather conditions, in sites less than 10 km distance from the sea and distributed over a rather small scale area (58651 km(2)). We studied how the strontium (Sr) isotopic signature and selected elemental concentrations ([Mn], [Cu], [Zn], [Rb], [Sr] and [Cd]) in early potatoes from three neighbouring administrative regions in the south of Italy were related to the geological substrate (alluvial sediments, volcanic substrates and carbonate rocks) and to selected soil chemical properties influencing the bioavailability of elements in soils (pH, cation exchange capacity and total carbonate content). Through multiple-step multivariate statistics (PLS-DA) we could assign 26 potatoes (including two already commercialised samples) to their respective eight sites of production, corresponding to the first two types of geological substrates. The other 12 potatoes from four sites of production had similar characteristics in terms of the geological substrate (third type) and these soil properties could be grouped together. In this case, more discriminative parameters would be required to allow the differentiation between sites. The validation of our models included external prediction tests with data of potatoes harvested the year before and a study on the robustness of the uncertainties of the measurement results. Annual variations between multi-elemental and Sr isotopic fingerprints were observed in potatoes harvested from soils overlying carbonate rocks, stressing the importance of testing long term variations in authentication studies. Copyright © 2011 John Wiley & Sons, Ltd. and European Union [2011].

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

Apps, John A.; Wilkin, Richard T.

This report contains a series of tables summarizing the thermodynamic properties of aqueous carbonate complexes and solid carbonate phases of the following elements: arsenic (As), barium (Ba), cadmium (Cd), chromium (Cr), cobalt (Co), copper (Cu), iron (Fe), lead (Pb), manganese (Mn), mercury (Hg), nickel (Ni) thallium (Tl), uranium (U) and zinc (Zn). Most of these elements are potentially hazardous as defined by extant primary drinking water standards of the United States Environmental Protection Agency (EPA). The remainder are not considered hazardous, but are either listed by EPA under secondary standards, or because they can adversely affect drinking water quality. Additionalmore » tables are included giving the thermodynamic properties for carbonates of the alkali metal and alkali earth elements, sodium (Na), potassium (K), magnesium (Mg), calcium (Ca), and strontium (Sr), because of their value in developing correlative models to estimate the thermodynamic properties of carbonate minerals for which no such data currently exist. The purpose in creating the tables in this report is to provide future investigators with a convenient source for selecting and tracing the sources of thermodynamic data of the above listed elements for use in modeling their geochemical behavior in “underground sources of drinking water” (USDW). The incentive for doing so lies with a heightened concern over the potential consequences of the proposed capture and storage of carbon dioxide (CO2) generated by fossil fuel fired power plants in deep subsurface reservoirs. If CO2 were to leak from such reservoirs, it could migrate upward and contaminate USDWs with undesirable, but undetermined, consequences to water quality. The EPA, Office of Research and Development, through an Interagency Agreement with the U.S. Department of Energy at the Lawrence Berkeley National Laboratory, funded the preparation of this report.« less

Electrocatalytic process for carbon dioxide conversion

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

Masel, Richard I.; Salehi-Khojin, Amin

2017-01-31

An electrocatalytic process for carbon dioxide conversion includes combining a Catalytically Active Element and Helper Catalyst in the presence of carbon dioxide, allowing a reaction to proceed to produce a reaction product, and applying electrical energy to said reaction to achieve electrochemical conversion of said reactant to said reaction product. The Catalytically Active Element can be a metal in the form of supported or unsupported particles or flakes with an average size between 0.6 nm and 100 nm. the reaction products comprise at least one of CO, HCO.sup.-, H.sub.2CO, (HCO.sub.2).sup.-, H.sub.2CO.sub.2, CH.sub.3OH, CH.sub.4, C.sub.2H.sub.4, CH.sub.3CH.sub.2OH, CH.sub.3COO.sup.-, CH.sub.3COOH, C.sub.2H.sub.6, (COOH).sub.2, (COO.sup.-).sub.2,more » and CF.sub.3COOH.« less

Vertically aligned carbon nanofibers and related structures: Controlled synthesis and directed assembly

NASA Astrophysics Data System (ADS)

Melechko, A. V.; Merkulov, V. I.; McKnight, T. E.; Guillorn, M. A.; Klein, K. L.; Lowndes, D. H.; Simpson, M. L.

2005-02-01

The controlled synthesis of materials by methods that permit their assembly into functional nanoscale structures lies at the crux of the emerging field of nanotechnology. Although only one of several materials families is of interest, carbon-based nanostructured materials continue to attract a disproportionate share of research effort, in part because of their wide-ranging properties. Additionally, developments of the past decade in the controlled synthesis of carbon nanotubes and nanofibers have opened additional possibilities for their use as functional elements in numerous applications. Vertically aligned carbon nanofibers (VACNFs) are a subclass of carbon nanostructured materials that can be produced with a high degree of control using catalytic plasma-enhanced chemical-vapor deposition (C-PECVD). Using C-PECVD the location, diameter, length, shape, chemical composition, and orientation can be controlled during VACNF synthesis. Here we review the CVD and PECVD systems, growth control mechanisms, catalyst preparation, resultant carbon nanostructures, and VACNF properties. This is followed by a review of many of the application areas for carbon nanotubes and nanofibers including electron field-emission sources, electrochemical probes, functionalized sensor elements, scanning probe microscopy tips, nanoelectromechanical systems (NEMS), hydrogen and charge storage, and catalyst support. We end by noting gaps in the understanding of VACNF growth mechanisms and the challenges remaining in the development of methods for an even more comprehensive control of the carbon nanofiber synthesis process.

Estimation of Effective Directional Strength of Single Walled Wavy CNT Reinforced Nanocomposite

NASA Astrophysics Data System (ADS)

Bhowmik, Krishnendu; Kumar, Pranav; Khutia, Niloy; Chowdhury, Amit Roy

2018-03-01

In this present work, single walled wavy carbon nanotube reinforced into composite has been studied to predict the effective directional strength of the nanocomposite. The effect of waviness on the overall Young’s modulus of the composite has been analysed using three dimensional finite element model. Waviness pattern of carbon nanotube is considered as periodic cosine function. Both long (continuous) and short (discontinuous) carbon nanotubes are being idealized as solid annular tube. Short carbon nanotube is modelled with hemispherical cap at its both ends. Representative Volume Element models have been developed with different waviness, height fractions, volume fractions and modulus ratios of carbon nanotubes. Consequently a micromechanics based analytical model has been formulated to derive the effective reinforcing modulus of wavy carbon nanotubes. In these models wavy single walled wavy carbon nanotubes are considered to be aligned along the longitudinal axis of the Representative Volume Element model. Results obtained from finite element analyses are compared with analytical model and they are found in good agreement.

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

Skidmore, Cary Bradford; Preston, Daniel N.

These are a set of slides for educational outreach to children on high explosives science. It gives an introduction to the elements involved in this science: carbon, hydrogen, nitrogen, and oxygen. Combined, these form the molecule HMX. Many pictures are also included to illustrate explosions.

Energetic materials and methods of tailoring electrostatic discharge sensitivity of energetic materials

DOEpatents

Daniels, Michael A.; Heaps, Ronald J.; Wallace, Ronald S.; Pantoya, Michelle L.; Collins, Eric S.

2016-11-01

An energetic material comprising an elemental fuel, an oxidizer or other element, and a carbon nanofiller or carbon fiber rods, where the carbon nanofiller or carbon fiber rods are substantially homogeneously dispersed in the energetic material. Methods of tailoring the electrostatic discharge sensitivity of an energetic material are also disclosed.

Soil Physical, Chemical, and Thermal Characterization, Council Road Site, Seward Peninsula, Alaska, 2016

DOE Data Explorer

Alexander Kholodov; David Graham; Ji-Won Moon

2018-01-22

This dataset provides the results of physical, chemical, and thermal characterization of soils at the Council Road Site at MM71, Seward Peninsula, Alaska. Soil pits were dug on 11 September 2016 at three sites. This dataset includes field observations and descriptions of soil layers or horizons, field measurements of soil volumetric water content, soil temperature, thermal conductivity, and heat capacity. Laboratory measurements of soil properties include gravimetric water content, bulk density, volumetric water content, total carbon and nitrogen, and elemental composition from X-ray fluorescence for some elements.

Electron-probe microanalysis of light elements in coal and other kerogen

USGS Publications Warehouse

Bustin, R.M.; Mastalerz, Maria; Raudsepp, M.

1996-01-01

Recent advances in electron microprobe technology including development of layered synthetic microstructures, more stable electronics and better matrix-correction programs facilitated routine microanalysis of the light elements in coal. Utilizing an appropriately equipped electron microprobe with suitable standards, it is now possible to analyze directly the light elements (C, O and N, if abundant) in coal macerals and other kerogen. The analytical results are both accurate compared to ASTM methods and highly precise, and provide an opportunity to access the variation in coal chemistry at the micrometre scale. Our experiments show that analyses using a 10 kV accelerating voltage and 10 nA beam current yield the most reliable data and result in minimum sample damage and contamination. High sample counts were obtained for C, O and N using a bi-elemental nickel-carbon pseudo-crystal (2d = 9.5 nm) as an analyzing crystal. Vitrinite isolated from anthracite rank coal proves the best carbon standard and is more desirable than graphite which has higher porosity, whereas lower rank vitrinite is too heterogeneous to use routinely as a standard. Other standards utilized were magnesite for oxygen and BN for nitrogen. No significant carbon, oxygen or nitrogen X-ray peak shifts or peak-shape changes occur between standards and the kerogen analyzed. Counting rates for carbon and oxygen were found to be constant over a range of beam sizes and currents for counting times up to 160 s. Probe-determined carbon and oxygen contents agree closely with those reported from ASTM analyses. Nitrogen analyses compare poorly to ASTM values which probably is in response to overlap between the nitrogen Ka peak with the carbon K-adsorption edge and the overall low nitrogen content of most of our samples. Our results show that the electron microprobe technique provides accurate compositional data for both minor and major elements in coal without the necessity and inherent problems associated with mechanically isolating macerals. Studies to date have demonstrated the level of compositional variability within and between macerals in suites of Canadian coals.

Ecosystem processes at the watershed scale: mapping and modeling ecohydrological controls

Treesearch

Lawrence E. Band; T. Hwang; T.C. Hales; James Vose; Chelcy Ford

2012-01-01

Mountain watersheds are sources of a set of valuable ecosystem services as well as potential hazards. The former include high quality freshwater, carbon sequestration, nutrient retention, and biodiversity, whereas the latter include flash floods, landslides and forest fires. Each of these ecosystem services and hazards represents different elements of the integrated...

What predictions can be made on the nature of carbon and carbon-bearing compounds (hydrocarbons) in the interstellar medium based on studies of interplanetary dust particles?

NASA Technical Reports Server (NTRS)

Rietmeijer, F. J. M.

1986-01-01

The nature of hydrocarbons and properties of elemental carbon in circumstellar, interstellar, and interplanetary dust is a long standing problem in astronomy and meteorite research. The textures and crystallographical properties of poorly graphitized carbon (PGC) from carbonaceous chondrites and Chondritic Porous Aggregates (CPAs) are comparable with PGCs formed by dehydrogenation and carbonization of hydrocarbon precursors under natural terrestrial and experimental conditions. A multistage model of hydrocarbon diagenesis in CPA and carbonaceous chondrite (proto-) planetary parent bodies was proposed in which hydrocarbons are subjected to low temperature hydrous pyrolysis. Continued efforts to recognize hydrocarbons and elemental phases in CPAs may allow understanding of the multistage hydrocarbon/elemental carbon model.

Influence of Wind Pressure on the Carbonation of Concrete

PubMed Central

Zou, Dujian; Liu, Tiejun; Du, Chengcheng; Teng, Jun

2015-01-01

Carbonation is one of the major deteriorations that accelerate steel corrosion in reinforced concrete structures. Many mathematical/numerical models of the carbonation process, primarily diffusion-reaction models, have been established to predict the carbonation depth. However, the mass transfer of carbon dioxide in porous concrete includes molecular diffusion and convection mass transfer. In particular, the convection mass transfer induced by pressure difference is called penetration mass transfer. This paper presents the influence of penetration mass transfer on the carbonation. A penetration-reaction carbonation model was constructed and validated by accelerated test results under high pressure. Then the characteristics of wind pressure on the carbonation were investigated through finite element analysis considering steady and fluctuating wind flows. The results indicate that the wind pressure on the surface of concrete buildings results in deeper carbonation depth than that just considering the diffusion of carbon dioxide. In addition, the influence of wind pressure on carbonation tends to increase significantly with carbonation depth. PMID:28793462

Influence of Wind Pressure on the Carbonation of Concrete.

PubMed

Zou, Dujian; Liu, Tiejun; Du, Chengcheng; Teng, Jun

2015-07-24

Carbonation is one of the major deteriorations that accelerate steel corrosion in reinforced concrete structures. Many mathematical/numerical models of the carbonation process, primarily diffusion-reaction models, have been established to predict the carbonation depth. However, the mass transfer of carbon dioxide in porous concrete includes molecular diffusion and convection mass transfer. In particular, the convection mass transfer induced by pressure difference is called penetration mass transfer. This paper presents the influence of penetration mass transfer on the carbonation. A penetration-reaction carbonation model was constructed and validated by accelerated test results under high pressure. Then the characteristics of wind pressure on the carbonation were investigated through finite element analysis considering steady and fluctuating wind flows. The results indicate that the wind pressure on the surface of concrete buildings results in deeper carbonation depth than that just considering the diffusion of carbon dioxide. In addition, the influence of wind pressure on carbonation tends to increase significantly with carbonation depth.

Photographic combustion characterization of LOX/Hydrocarbon type propellants

NASA Technical Reports Server (NTRS)

Judd, D. C.

1980-01-01

One hundred twenty-seven tests were conducted over a chamber pressure range of 125-1500 psia, a fuel temperature range of -245 F to 158 F, and a fuel velocity range of 48-707 ft/sec to demonstrate the advantages and limitations of using high speed photography to identify potential combustion anomalies such as pops, fuel freezing, reactive stream separation and carbon formations. Combustion evaluation criteria were developed to guide selection of the fuels, injector elements, and operating conditions for testing. Separate criteria were developed for fuel and injector element selection and evaluation. The photographic test results indicated conclusively that injector element type and design directly influence carbon formation. Unlike spray fan, impingement elements reduce carbon formation because they induce a relatively rapid near zone fuel vaporization rate. Coherent jet impingement elements, on the other hand, exhibit increased carbon formation.

Understanding the adsorptive interactions of arsenate-iron nanoparticles with curved fullerene-like sheets in activated carbon using a quantum mechanics/molecular mechanics computational approach.

PubMed

Ha, Nguyen Ngoc; Cam, Le Minh; Ha, Nguyen Thi Thu; Goh, Bee-Min; Saunders, Martin; Jiang, Zhong-Tao; Altarawneh, Mohammednoor; Dlugogorski, Bogdan Z; El-Harbawi, Mohanad; Yin, Chun-Yang

2017-06-07

The prevalence of global arsenic groundwater contamination has driven widespread research on developing effective treatment systems including adsorption using various sorbents. The uptake of arsenic-based contaminants onto established sorbents such as activated carbon (AC) can be effectively enhanced via immobilization/impregnation of iron-based elements on the porous AC surface. Recent suggestions that AC pores structurally consist of an eclectic mix of curved fullerene-like sheets may affect the arsenic adsorption dynamics within the AC pores and is further complicated by the presence of nano-sized iron-based elements. We have therefore, attempted to shed light on the adsorptive interactions of arsenate-iron nanoparticles with curved fullerene-like sheets by using hybridized quantum mechanics/molecular mechanics (QMMM) calculations and microscopy characterization. It is found that, subsequent to optimization, chemisorption between HAsO 4 2- and the AC carbon sheet (endothermic process) is virtually non-existent - this observation is supported by experimental results. Conversely, the incorporation of iron nanoparticles (FeNPs) into the AC carbon sheet greatly facilitates chemisorption of HAsO 4 2- . Our calculation implies that iron carbide is formed at the junction between the iron and the AC interface and this tightly chemosorbed layer prevents detachment of the FeNPs on the AC surface. Other aspects including electronic structure/properties, carbon arrangement defects and rate of adsorptive interaction, which are determined using the Climbing-Image NEB method, are also discussed.

Nanometer-sized materials for solid-phase extraction of trace elements.

PubMed

Hu, Bin; He, Man; Chen, Beibei

2015-04-01

This review presents a comprehensive update on the state-of-the-art of nanometer-sized materials in solid-phase extraction (SPE) of trace elements followed by atomic-spectrometry detection. Zero-dimensional nanomaterials (fullerene), one-dimensional nanomaterials (carbon nanotubes, inorganic nanotubes, and nanowires), two-dimensional nanomaterials (nanofibers), and three-dimensional nanomaterials (nanoparticles, mesoporous nanoparticles, magnetic nanoparticles, and dendrimers) for SPE are discussed, with their application for trace-element analysis and their speciation in different matrices. A variety of other novel SPE sorbents, including restricted-access sorbents, ion-imprinted polymers, and metal-organic frameworks, are also discussed, although their applications in trace-element analysis are relatively scarce so far.

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

Young, B.C.; Musich, M.A.

A fixed-bed reactor system with continuous Hg{sup 0} analysis capabilities was used to evaluate commercial carbon sorbents for the removal of elemental mercury from simulated flue gas. The objectives of the program were to compare the sorbent effectiveness under identical test conditions and to identify the effects of various flue gas components on elemental mercury sorption. Sorbents tested included steam-activated lignite, chemically activated hardwood, chemically activated bituminous coal, iodated steam-activated coconut shell, and sulfur-impregnated steam-activated bituminous coal. The iodated carbon was the most effective sorbent, showing over 99% mercury removal according to U.S. Environmental Protection Agency (EPA) Method 101A. Datamore » indicate that adding O{sub 2} at 4 vol% reduced the effectiveness of the steam-activated lignite, chemically activated hardwood, and sulfur- impregnated steam-activated bituminous coal. Adding SO{sub 2} at 500 ppm improved the mercury removal of the sulfur-impregnated carbon. Further, the presence of HCl gas (at 50 ppm) produced an order of magnitude increase in mercury removal with the chemically activated and sulfur-impregnated bituminous coal-based carbons.« less

Functionally gradient hard carbon composites for improved adhesion and wear

NASA Astrophysics Data System (ADS)

Narayan, Roger Jagdish

A new approach is proposed for fabricating biomedical devices that last longer and are more biocompatible than those presently available. In this approach, a bulk material is chosen that has desirable mechanical properties (low modulus, high strength, high ductility and high fatigue strength). This material is coated with corrosion-resistant, wear-resistant, hard, and biocompatible hard carbon films. One of the many forms of carbon, tetrahedral amorphous carbon, consists mainly of sp3-bonded atoms. Tetrahedral amorphous carbon possesses properties close to diamond in terms of hardness, atomic smoothness, and inertness. Tetrahedral amorphous carbon and diamond films usually contain large amounts of compressive and sometimes tensile stresses; adhesive failure from these stresses has limited widespread use of these materials. This research involves processing, characterization and modeling of functionally gradient tetrahedral amorphous carbon and diamond composite films on metals (cobalt-chromium and titanium alloys) and polymers (polymethylmethacrylate and polyethylene) used in biomedical applications. Multilayer discontinuous thin films of titanium carbide, titanium nitride, aluminum nitride, and tungsten carbide have been developed to control stresses and graphitization in diamond films. A morphology of randomly interconnected micron sized diamond crystallites provides increased toughness and stress reduction. Internal stresses in tetrahedral amorphous carbon were reduced via incorporation of carbide forming elements (silicon and titanium) and noncarbide forming elements (copper, platinum, and silver). These materials were produced using a novel target design during pulsed laser deposition. These alloying atoms reduce hardness and sp3-bonded carbon content, but increase adhesion and wear resistance. Silver and platinum provide the films with antimicrobial properties, and silicon provides bioactivity and aids bone formation. Bilayer coatings were created that couple the adherence, biocompatibility, erosion resistance, and long term release of functional elements from hard carbon coatings with bioactive properties of nanocrystalline hydroxyapatite and short term drug release properties of resorbable poly (D,L) lactide-based materials. Finally, these hard carbon coatings have a variety of non-medical applications, including use in microelectronics packaging, sensors, flat panel displays, photodiodes, cutting tools, optical switches, and wear-resistant magnetic disks.

Method 440.0 Determination of Carbon and Nitrogen in Sediments and Particulatesof Estuarine/Coastal Waters Using Elemental Analysis

EPA Science Inventory

Elemental analysis is used to determine particulate carbon (PC) and particulate nitrogen (PN) in estuarine and coastal waters and sediment. The method measures the total carbon and nitrogen irrespective of source (inorganic or organic).

Natural fracking and the genesis of five-element veins

NASA Astrophysics Data System (ADS)

Markl, Gregor; Burisch, Mathias; Neumann, Udo

2016-08-01

Hydrothermal Ag-Co-Ni-Bi-As (five-element vein type) ore deposits show very conspicuous textures of the native elements silver, bismuth, and arsenic indicating formation from a rapid, far-from-equilibrium process. Such textures include up to dm-large tree- and wire-like aggregates overgrown by Co-Ni-Fe arsenides and mostly carbonates. Despite the historical and contemporary importance of five-element vein type deposits as sources of silver, bismuth, and cobalt, and despite of spectacular museum specimens, their process of formation is not yet understood and has been a matter of debate since centuries. We propose, based on observations from a number of classical European five-element vein deposits and carbon isotope analyses, that "natural fracking," i.e., liberation of hydrocarbons or hydrocarbon-bearing fluids during break up of rocks in the vicinity of an active hydrothermal system and mixing between these hydrocarbons (e.g., methane and/or methane-bearing fluids) and a metal-rich hydrothermal fluid is responsible for ore precipitation and the formation of the unusual ore textures and assemblages. Thermodynamic and isotope mixing calculations show that the textural, chemical, and isotopic features of the investigated deposits can entirely be explained by this mechanism.

On the heat capacity of elements in WMD regime

NASA Astrophysics Data System (ADS)

Hamel, Sebatien

2014-03-01

Once thought to get simpler with increasing pressure, elemental systems have been discovered to exhibit complex structures and multiple phases at high pressure. For carbon, QMD/PIMC simulations have been performed and the results are guiding alternative modelling methodologies for constructing a carbon equation-of-state covering the warm dense matter regime. One of the main results of our new QMD/PIMC carbon equation of state is that the decay of the ion-thermal specific heat with temperature is much faster than previously expected. An important question is whether this is only found in carbon and not other element. In this presentation, based on QMD calculations for several elements, we explore trends in the transition from condensed matter to warm dense matter regime.

Processing of metal and oxygen from lunar deposits

NASA Technical Reports Server (NTRS)

Acton, Constance F.

1992-01-01

On the moon, some whole rocks may be ores for abundant elements, such as oxygen, but beneficiation will be important if metallic elements are sought from raw lunar dirt. In the extraction process, a beneficiated metallic ore, such as an oxide, sulfide, carbonate, or silicate mineral, is converted to reduced metal. A variety of plausible processing technologies, which includes recovery of meteoritic iron, and processing of lunar ilmenite, are described in this report.

Nuclear fuel elements and method of making same

DOEpatents

Schweitzer, Donald G.

1992-01-01

A nuclear fuel element for a high temperature gas nuclear reactor that has an average operating temperature in excess of 2000.degree. C., and a method of making such a fuel element. The fuel element is characterized by having fissionable fuel material localized and stabilized within pores of a carbon or graphite member by melting the fissionable material to cause it to chemically react with the carbon walls of the pores. The fissionable fuel material is further stabilized and localized within the pores of the graphite member by providing one or more coatings of pyrolytic carbon or diamond surrounding the porous graphite member so that each layer defines a successive barrier against migration of the fissionable fuel from the pores, and so that the outermost layer of pyrolytic carbon or diamond forms a barrier between the fissionable material and the moderating gases used in an associated high temperature gas reactor. The method of the invention provides for making such new elements either as generally spherically elements, or as flexible filaments, or as other relatively small-sized fuel elements that are particularly suited for use in high temperature gas reactors.

AN ELEMENTAL ASSAY OF VERY, EXTREMELY, AND ULTRA-METAL-POOR STARS

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

Hansen, T.; Christlieb, N.; Hansen, C. J.

2015-07-10

We present a high-resolution elemental-abundance analysis for a sample of 23 very metal-poor ([Fe/H] < −2.0) stars, 12 of which are extremely metal-poor ([Fe/H] < −3.0), and 4 of which are ultra-metal-poor ([Fe/H] < −4.0). These stars were targeted to explore differences in the abundance ratios for elements that constrain the possible astrophysical sites of element production, including Li, C, N, O, the α-elements, the iron-peak elements, and a number of neutron-capture elements. This sample substantially increases the number of known carbon-enhanced metal-poor (CEMP) and nitrogen-enhanced metal-poor (NEMP) stars—our program stars include eight that are considered “normal” metal-poor stars, sixmore » CEMP-no stars, five CEMP-s stars, two CEMP-r stars, and two CEMP-r/s stars. One of the CEMP-r stars and one of the CEMP-r/s stars are possible NEMP stars. We detect lithium for three of the six CEMP-no stars, all of which are Li depleted with respect to the Spite plateau. The majority of the CEMP stars have [C/N] > 0. The stars with [C/N] < 0 suggest a larger degree of mixing; the few CEMP-no stars that exhibit this signature are only found at [Fe/H] < −3.4, a metallicity below which we also find the CEMP-no stars with large enhancements in Na, Mg, and Al. We confirm the existence of two plateaus in the absolute carbon abundances of CEMP stars, as suggested by Spite et al. We also present evidence for a “floor” in the absolute Ba abundances of CEMP-no stars at A(Ba) ∼ −2.0.« less

EFFECT OF MOISTURE ON ADSORPTION OF ELEMENTAL MERCURY BY ACTIVATED CARBON

EPA Science Inventory

The paper discusses experiments using activated carbon to capture elemental mercury (Hgo), and a bench-scale dixed-bed reactor and a flow reactor to determine the role of surface moisture in Hgo adsorption. Three activated-carbon samples, with different pore structure and ash co...

The Diesel Exhaust in Miners Study: III. Interrelations between respirable elemental carbon and gaseous and particulate components of diesel exhaust derived from area sampling in underground non-metal mining facilities.

PubMed

Vermeulen, Roel; Coble, Joseph B; Yereb, Daniel; Lubin, Jay H; Blair, Aaron; Portengen, Lützen; Stewart, Patricia A; Attfield, Michael; Silverman, Debra T

2010-10-01

Diesel exhaust (DE) has been implicated as a potential lung carcinogen. However, the exact components of DE that might be involved have not been clearly identified. In the past, nitrogen oxides (NO(x)) and carbon oxides (CO(x)) were measured most frequently to estimate DE, but since the 1990s, the most commonly accepted surrogate for DE has been elemental carbon (EC). We developed quantitative estimates of historical exposure levels of respirable elemental carbon (REC) for an epidemiologic study of mortality, particularly lung cancer, among diesel-exposed miners by back-extrapolating 1998-2001 REC exposure levels using historical measurements of carbon monoxide (CO). The choice of CO was based on the availability of historical measurement data. Here, we evaluated the relationship of REC with CO and other current and historical components of DE from side-by-side area measurements taken in underground operations of seven non-metal mining facilities. The Pearson correlation coefficient of the natural log-transformed (Ln)REC measurements with the Ln(CO) measurements was 0.4. The correlation of REC with the other gaseous, organic carbon (OC), and particulate measurements ranged from 0.3 to 0.8. Factor analyses indicated that the gaseous components, including CO, together with REC, loaded most strongly on a presumed 'Diesel exhaust' factor, while the OC and particulate agents loaded predominantly on other factors. In addition, the relationship between Ln(REC) and Ln(CO) was approximately linear over a wide range of REC concentrations. The fact that CO correlated with REC, loaded on the same factor, and increased linearly in log-log space supported the use of CO in estimating historical exposure levels to DE.

The Diesel Exhaust in Miners Study: III. Interrelations between Respirable Elemental Carbon and Gaseous and Particulate Components of Diesel Exhaust derived from Area Sampling in Underground Non-metal Mining Facilities

PubMed Central

Vermeulen, Roel; Coble, Joseph B.; Yereb, Daniel; Lubin, Jay H.; Blair, Aaron; Portengen, Lützen; Stewart, Patricia A.; Attfield, Michael; Silverman, Debra T.

2010-01-01

Diesel exhaust (DE) has been implicated as a potential lung carcinogen. However, the exact components of DE that might be involved have not been clearly identified. In the past, nitrogen oxides (NOx) and carbon oxides (COx) were measured most frequently to estimate DE, but since the 1990s, the most commonly accepted surrogate for DE has been elemental carbon (EC). We developed quantitative estimates of historical exposure levels of respirable elemental carbon (REC) for an epidemiologic study of mortality, particularly lung cancer, among diesel-exposed miners by back-extrapolating 1998–2001 REC exposure levels using historical measurements of carbon monoxide (CO). The choice of CO was based on the availability of historical measurement data. Here, we evaluated the relationship of REC with CO and other current and historical components of DE from side-by-side area measurements taken in underground operations of seven non-metal mining facilities. The Pearson correlation coefficient of the natural log-transformed (Ln)REC measurements with the Ln(CO) measurements was 0.4. The correlation of REC with the other gaseous, organic carbon (OC), and particulate measurements ranged from 0.3 to 0.8. Factor analyses indicated that the gaseous components, including CO, together with REC, loaded most strongly on a presumed ‘Diesel exhaust’ factor, while the OC and particulate agents loaded predominantly on other factors. In addition, the relationship between Ln(REC) and Ln(CO) was approximately linear over a wide range of REC concentrations. The fact that CO correlated with REC, loaded on the same factor, and increased linearly in log–log space supported the use of CO in estimating historical exposure levels to DE. PMID:20876234

Conductometric Sensors for Detection of Elemental Mercury Vapor

NASA Technical Reports Server (NTRS)

Ryan, M. A.; Homer, M. L.; Shevade, A. V.; Lara, L. M.; Yen, S.-P. S.; Kisor, A. K.; Manatt, K. S.

2008-01-01

Several organic and inorganic materials have been tested for possible incorporation into a sensing array in order to add elemental mercury vapor to the suite of chemical species detected. Materials have included gold films, treated gold films, polymer-carbon composite films, gold-polymer-carbon composite films and palladium chloride sintered films. The toxicity of mercury and its adverse effect on human and animal health has made environmental monitoring of mercury in gas and liquid phases important (1,2). As consumer products which contain elemental mercury, such as fluorescent lighting, become more widespread, the need to monitor environments for the presence of vapor phase elemental mercury will increase. Sensors in use today to detect mercury in gaseous streams are generally based on amalgam formation with gold or other metals, including noble metals and aluminum. Recently, NASA has recognized a need to detect elemental mercury vapor in the breathing atmosphere of the crew cabin in spacecraft and has requested that such a capability be incorporated into the JPL Electronic Nose (3). The detection concentration target for this application is 10 parts-per-billion (ppb), or 0.08 mg/m3. In order to respond to the request to incorporate mercury sensing into the JPL Electronic Nose (ENose) platform, it was necessary to consider only conductometric methods of sensing, as any other transduction method would have required redesign of the platform. Any mercury detection technique which could not be incorporated into the existing platform, such as an electrochemical technique, could not be considered.

Multiple-element semiquantitative analysis of one-milligram geochemical samples by D.C. arc emission spectrography

USGS Publications Warehouse

Rait, N.

1981-01-01

A modified method is described for a 1-mg sample multi-element semiquantitative spectrographic analysis. This method uses a direct-current arc source, carbon instead of graphite electrodes, and an 80% argon-20% oxygen atmosphere instead of air. Although this is a destructive method, an analysis can be made for 68 elements in all mineral and geochemical samples. Carbon electrodes have been an aid in improving the detection limits of many elements. The carbon has a greater resistance to heat conductance and develops a better tip, facilitating sample volatilization and counter balancing the cooling effect of a flow of the argon-oxygen mixture around the anode. Where such an argon-oxygen atmosphere is used instead of air, the cyanogen band lines are greatly diminished in intensity, and thus more spectral lines of analysis elements are available for use; the spectral background is also lower. The main advantage of using the carbon electrode and the 80% argon-20% oxygen atmosphere is the improved detection limits of 36 out of 68 elements. The detection limits remain the same for 23 elements, and are not as good for only nine elements. ?? 1981.

Closing the carbon balance for fermentation by Clostridium thermocellum (ATCC 27405).

PubMed

Ellis, Lucas D; Holwerda, Evert K; Hogsett, David; Rogers, Steve; Shao, Xiongjun; Tschaplinski, Timothy; Thorne, Phil; Lynd, Lee R

2012-01-01

Our lab and most others have not been able to close a carbon balance for fermentation by the thermophilic, cellulolytic anaerobe, Clostridium thermocellum. We undertook a detailed accounting of product formation in C. thermocellum ATCC 27405. Elemental analysis revealed that for both cellulose (Avicel) and cellobiose, ≥92% of the substrate carbon utilized could be accounted for in the pellet, supernatant and off-gas when including sampling. However, 11.1% of the original substrate carbon was found in the liquid phase and not in the form of commonly-measured fermentation products--ethanol, acetate, lactate, and formate. Further detailed analysis revealed all the products to be <720 da and have not usually been associated with C. thermocellum fermentation, including malate, pyruvate, uracil, soluble glucans, and extracellular free amino acids. By accounting for these products, 92.9% and 93.2% of the final product carbon was identified during growth on cellobiose and Avicel, respectively. Copyright © 2011 Elsevier Ltd. All rights reserved.

Simply scan--optical methods for elemental carbon measurement in diesel exhaust particulate.

PubMed

Forder, James A

2014-08-01

This article describes a performance assessment of three optical methods, a Magee Scientific OT21 Transmissometer, a Hach-Lange Microcolor II difference gloss meter, and a combination of an office scanner with Adobe Photoshop software. The optical methods measure filter staining as a proxy for elemental carbon in diesel exhaust particulate (DEP) exposure assessment and the suitability of each as a replacement for the existing Bosch meter optical method. Filters loaded with DEP were produced from air in a non-coal mine and the exhaust gases from a mobile crane. These were measured with each apparatus and then by combustion to obtain a reference elemental carbon value. The results from each apparatus were then plotted against both the Bosch number and reference elemental carbon values. The equations of the best fit lines for these plots were derived, and these gave functions for elemental carbon and Bosch number from the output of each new optical method. For each optical method, the range of DEP loadings which can be measured has been determined, and conversion equations for elemental carbon and Bosch number have been obtained. All three optical methods studied will effectively quantify blackness as a measure of elemental carbon. Of these the Magee Scientific OT21 transmissometer has the best performance. The Microcolor II and scanner/photoshop methods will in addition allow conversion to Bosch number which may be useful if historical Bosch data are available and functions for this are described. The scanner/photoshop method demonstrates a technique to obtain measurements of DEP exposure without the need to purchase specialized instrumentation. © The Author 2014. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.

Towards the isolation and estimation of elemental carbon in atmospheric aerosols using supercritical fluid extraction and thermo-optical analysis.

PubMed

Azeem, Hafiz Abdul; Martinsson, Johan; Stenström, Kristina Eriksson; Swietlicki, Erik; Sandahl, Margareta

2017-07-01

Air-starved combustion of biomass and fossil fuels releases aerosols, including airborne carbonaceous particles, causing negative climatic and health effects. Radiocarbon analysis of the elemental carbon (EC) fraction can help apportion sources of its emission, which is greatly constrained by the challenges in isolation of EC from organic compounds in atmospheric aerosols. The isolation of EC using thermo-optical analysis is however biased by the presence of interfering compounds that undergo pyrolysis during the analysis. EC is considered insoluble in all acidic, basic, and organic solvents. Based on the property of insolubility, a sample preparation method using supercritical CO 2 and methanol as co-solvent was developed to remove interfering organic compounds. The efficiency of the method was studied by varying the density of supercritical carbon dioxide by means of temperature and pressure and by varying the methanol content. Supercritical CO 2 with 10% methanol by volume at a temperature of 60 °C, a pressure of 350 bar and 20 min static mode extraction were found to be the most suitable conditions for the removal of 59 ± 3% organic carbon, including compounds responsible for pyrolysis with 78 ± 16% EC recovery. The results indicate that the method has potential for the estimation and isolation of EC from OC for subsequent analysis methods and source apportionment studies.

SAMPLING ARTIFACTS IN MEASUREMENT OF ELEMENTAL AND ORGANIC CARBON: LOW VOLUME SAMPLING IN INDOOR AND OUTDOOR ENVIRONMENTS

EPA Science Inventory

Experiments were completed to determine the extent of artifacts from sampling elemental carbon (EC) and organic carbon (OC) under sample conditions consistent with personal sampling. Two different types of experiments were completed; the first examined possible artifacts from oil...

IMPORTANCE OF ACTIVATED CARBON'S OXYGEN SURFACE FUNCTIONAL GROUPS ON ELEMENTAL MERCURY ADSORPTION

EPA Science Inventory

The effect of varying physical and chemical properties of activated carbons on adsorption of elemental mercury [Hg(0)] was studied by treating two activated carbons to modify their surface functional groups and pore structures. Heat treatment (1200 K) in nitrogen (N2), air oxidat...

ELEMENTAL MERCURY CAPTURE BY ACTIVATED CARBON IN A FLOW REACTOR

EPA Science Inventory

The paper gives results of bench-scale experiments in a flow reactor to simulate the entrained-flow capture of elemental mercury (Hgo) using solid sorbents. Adsorption of Hgo by a lignite-based activated carbon (Calgon FGD) was examined at different carbon/mercury (C/Hg) rat...

IN-FLIGHT CAPTURE OF ELEMENTAL MERCURY BY A CHLORINE-IMPREGNATED ACTIVATED CARBON

EPA Science Inventory

The paper discusses the in-flight capture of elemental mercury (Hgo) by a chlorine (C1)-impregnated activated carbon. Efforts to develop sorbents for the control of Hg emissions have demonstrated that C1-impregnation of virgin activated carbons using dilute solutions of hydrogen ...

DEVELOPMENT OF A CL-IMPREGNATED ACTIVATED CARBON FOR ENTRAINED-FLOW CAPTURE OF ELEMENTAL MERCURY

EPA Science Inventory

Efforts to discern the role of an activated carbon's surface functional groups on the adsorption of elemental mercury [Hg(0)] and mercuric chloride demonstrated that chlorine (Cl) impregnation of a virgin activated carbon using dilute solutions of hydrogen chloride leads to incre...

Symposium on the Tropospheric Chemistry of the Antarctic Region: Pre- Conference Abstracts

DTIC Science & Technology

1991-06-01

and composition); elemental carbon particles can scatter and absorb solar radiation. In addition, molecular species present as organic carbon aerosol ...elemental carbon to organic carbon aerosol particles are measured. This accounting pro- vides useful information needed to describe the ambient levels... Particle Analysis of Five Years of Aerosol Sampling in the Antarctic Peninsula P. Artaxo, W. M aenhaut and Rend Van Grieken

PRIMARY AND SECONDARY ORGANIC AEROSOLS OVER THE UNITED STATES: ESTIMATES ON THE BASIS OF OBSERVED ORGANIC CARBON (OC) AND ELEMENTAL CARBON (EC), AND AIR QUALITY MODELED PRIMARY (OC/EC) RATIOS

EPA Science Inventory

The temporal and spatial distributions of primary and secondary organic carbon aerosols (OC) over the continental US during June 15 to August 31, 1999, were estimated by using observational OC and elemental carbon (EC) data from Interagency Monitoring of Protected Visual Environm...

Catalyst-induced growth of carbon nanotubes on tips of cantilevers and nanowires

DOEpatents

Lee, James Weifu; Lowndes, Douglas H.; Merkulov, Vladimir I.; Eres, Gyula; Wei, Yayi; Greenbaum, Elias; Lee, Ida

2004-06-29

A method is described for catalyst-induced growth of carbon nanotubes, nanofibers, and other nanostructures on the tips of nanowires, cantilevers, conductive micro/nanometer structures, wafers and the like. The method can be used for production of carbon nanotube-anchored cantilevers that can significantly improve the performance of scaning probe microscopy (AFM, EFM etc). The invention can also be used in many other processes of micro and/or nanofabrication with carbon nanotubes/fibers. Key elements of this invention include: (1) Proper selection of a metal catalyst and programmable pulsed electrolytic deposition of the desired specific catalyst precisely at the tip of a substrate, (2) Catalyst-induced growth of carbon nanotubes/fibers at the catalyst-deposited tips, (3) Control of carbon nanotube/fiber growth pattern by manipulation of tip shape and growth conditions, and (4) Automation for mass production.

Method of depositing multi-layer carbon-based coatings for field emission

DOEpatents

Sullivan, John P.; Friedmann, Thomas A.

1999-01-01

A novel field emitter device for cold cathode field emission applications, comprising a multi-layer resistive carbon film. The multi-layered film of the present invention is comprised of at least two layers of a resistive carbon material, preferably amorphous-tetrahedrally coordinated carbon, such that the resistivities of adjacent layers differ. For electron emission from the surface, the preferred structure comprises a top layer having a lower resistivity than the bottom layer. For edge emitting structures, the preferred structure of the film comprises a plurality of carbon layers, wherein adjacent layers have different resistivities. Through selection of deposition conditions, including the energy of the depositing carbon species, the presence or absence of certain elements such as H, N, inert gases or boron, carbon layers having desired resistivities can be produced. Field emitters made according the present invention display improved electron emission characteristics in comparison to conventional field emitter materials.

Method of depositing multi-layer carbon-based coatings for field emission

DOEpatents

Sullivan, J.P.; Friedmann, T.A.

1999-08-10

A novel field emitter device is disclosed for cold cathode field emission applications, comprising a multi-layer resistive carbon film. The multi-layered film of the present invention is comprised of at least two layers of a resistive carbon material, preferably amorphous-tetrahedrally coordinated carbon, such that the resistivities of adjacent layers differ. For electron emission from the surface, the preferred structure comprises a top layer having a lower resistivity than the bottom layer. For edge emitting structures, the preferred structure of the film comprises a plurality of carbon layers, wherein adjacent layers have different resistivities. Through selection of deposition conditions, including the energy of the depositing carbon species, the presence or absence of certain elements such as H, N, inert gases or boron, carbon layers having desired resistivities can be produced. Field emitters made according the present invention display improved electron emission characteristics in comparison to conventional field emitter materials. 8 figs.

Quality of ground water for selected municipal water supplies in Iowa, 1997-2002

USGS Publications Warehouse

Littin, Gregory R.

2004-01-01

The compact disc included with this report has information about water-quality properties and concentrations of dissolved solids, major ions, nutrients, trace elements, radionuclides, total organic carbon, pesticides, and synthetic organic compounds for water years 1997 through 2002.

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.

Comparison and evaluation of in situ and filter carbon measurements at the Fresno Supersite

NASA Astrophysics Data System (ADS)

Watson, John G.; Chow, Judith C.

2002-11-01

The Fresno Supersite in Fresno, California, USA, acquires in situ 5- to 60-min average PM2.5 organic carbon (OC), elemental carbon (EC), and total carbon (TC) measurements by the following methods: (1) thermal evolution carbon analyzer for organic, elemental, and total carbon; (2) single-wavelength and seven-color aethalometer for black carbon (BC); and (3) photoionization for particle-bound polycyclic aromatic hydrocarbons. Twenty-four-hour average PM2.5 filter-based measurements include (1) nondenuded quartz filters with no backup filter in a PM2.5 Federal Reference Method (FRM) sampler; (2) quartz filters behind an organic carbon denuder with a quartz backup filter in a Reference Ambient Aerosol Sampler (RAAS); (3) nondenuded quartz filters with backup filter in a RAAS; and (4) nondenuded quartz filters with no backup filter in a sequential filter sampler. Filter samples are analyzed after sampling by the Interagency Monitoring of Protected Visual Environments (IMPROVE) thermal/optical reflectance carbon analysis protocol. Collocated measurements are examined for year 2000. Measurement equivalence is found for PM2.5 mass, light transmission, and TC between the FRM and RAAS speciation samplers. The average ratios of front filter carbon between the denuded and nondenuded channels in the RAAS sampler are 0.83 ± 0.19 for TC, 0.81 ± 0.20 for OC, and 1.01 ± 0.33 for EC. The average differences for TC and OC are low (1.2 to 1.4 μg m-3) and are comparable to the measurement uncertainties. Continuous thermal evolution carbon measurements are not comparable to filter measurements. Aethalometer BC and filter EC are highly correlated, but filter EC is consistently 20-25% higher than continuous aethalometer BC. Pairwise comparisons show filter EC measurements acquired in this study are predictable from aethalometer BC measurements.

Marine and Freshwater Feedstocks as a Precursor for Nitrogen-Containing Carbons: A Review

PubMed Central

Ilnicka, Anna; Lukaszewicz, Jerzy P.

2018-01-01

Marine-derived as well as freshwater feedstock offers important benefits, such as abundance, morphological and structural variety, and the presence of multiple elements, including nitrogen and carbon. Therefore, these renewal resources may be useful for obtaining N- and C-containing materials that can be manufactured by various methods, such as pyrolysis and hydrothermal processes supported by means of chemical and physical activators. However, every synthesis concept relies on an efficient transfer of nitrogen and carbon from marine/freshwater feedstock to the final product. This paper reviews the advantages of marine feedstock over synthetic and natural but non-marine resources as precursors for the manufacturing of N-doped activated carbons. The manufacturing procedure influences some crucial properties of nitrogen-doped carbon materials, such as pore structure and the chemical composition of the surface. An extensive review is given on the relationship between carbon materials manufacturing from marine feedstock and the elemental content of nitrogen, together with a description of the chemical bonding of nitrogen atoms at the surface. N-doped carbons may serve as effective adsorbents for the removal of pollutants from the gas or liquid phase. Non-recognized areas of adsorption-based applications for nitrogen-doped carbons are presented, too. The paper proves that nitrogen-doped carbon materials belong to most of the prospective electrode materials for electrochemical energy conversion and storage technologies such as fuel cells, air–metal batteries, and supercapacitors, as well as for bioimaging. The reviewed material belongs to the widely understood field of marine biotechnology in relation to marine natural products. PMID:29701697

Interactions between CO2, minerals, and toxic ions: Implications for CO2 leakage from deep geological storage (Invited)

NASA Astrophysics Data System (ADS)

Renard, F.; Montes-Hernandez, G.

2013-12-01

The long-term injection of carbon dioxide into geological underground reservoirs may lead to leakage events that will enhance fluid-rock interactions and question the safety of these repositories. If injection of carbon dioxide into natural reservoirs has been shown to mobilize some species into the pore fluid, including heavy metals and other toxic ions, the detailed interactions remain still debated because two main processes could interact and modify fluid composition: on the one hand dissolution/precipitation reactions may release/incorporate trace elements, and on the other hand adsorption/desorption reactions on existing mineral surfaces may also mobilize or trap these elements. We analyze here, through laboratory experiments, a scenario of a carbon dioxide reservoir that leaks into a fresh water aquifer through a localized leakage zone such as a permeable fault zone localized in the caprock and enhance toxic ions mobilization. Our main goal is to evaluate the potential risks on potable water quality. In a series of experiments, we have injected carbon dioxide into a fresh water aquifer-like medium that contained carbonate and/or iron oxide particles, pure water, and various concentrations of trace elements (copper, arsenic, cadmium, and selenium, in various states of oxidation). This analogue and simplified medium has been chosen because it contains two minerals (calcite, goethite) widespread found in freshwater aquifers. The surface charge of these minerals may vary with pH and therefore control how trace elements are adsorbed or desorbed, depending on fluid composition. Our experiments show that these minerals could successfully prevent the remobilization of adsorbed Cu(II), Cd(II), Se(IV), and As(V) if carbon dioxide is intruded into a drinking water aquifer. Furthermore, a decrease in pH resulting from carbon dioxide intrusion could reactivate the adsorption of Se(IV) and As(V) if goethite and calcite are sufficiently available in the aquifer. Our results also suggest that adsorption of cadmium and copper could be promoted by calcite dissolution. These ions adsorbed on calcite are not remobilized when carbon dioxide is intruded into the system, even if calcite dissolution is intensified. On the other hand, arsenite As(III), significantly adsorbed on goethite, is partially remobilized by carbon dioxide intrusion. These results show that carbon dioxide may, in some case remobilize some toxic ions in the pore fluid, but the pH effect may also enhance adsorption of other toxic ione on calcite and goethite particles.

Bifunctional air electrodes containing elemental iron powder charging additive

DOEpatents

Liu, Chia-tsun; Demczyk, Brian G.; Gongaware, Paul R.

1982-01-01

A bifunctional air electrode for use in electrochemical energy cells is made, comprising a hydrophilic layer and a hydrophobic layer, where the hydrophilic layer essentially comprises a hydrophilic composite which includes: (i) carbon; (ii) elemental iron particles having a particle size of between about 25 microns and about 700 microns diameter; (iii) an oxygen evolution material; (iv) a nonwetting agent; and (v) a catalyst, where at least one current collector is formed into said composite.

Initial Risk Analysis and Decision Making Framework

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

Engel, David W.

2012-02-01

Commercialization of new carbon capture simulation initiative (CCSI) technology will include two key elements of risk management, namely, technical risk (will process and plant performance be effective, safe, and reliable) and enterprise risk (can project losses and costs be controlled within the constraints of market demand to maintain profitability and investor confidence). Both of these elements of risk are incorporated into the risk analysis subtask of Task 7. Thus far, this subtask has developed a prototype demonstration tool that quantifies risk based on the expected profitability of expenditures when retrofitting carbon capture technology on a stylized 650 MW pulverized coalmore » electric power generator. The prototype is based on the selection of specific technical and financial factors believed to be important determinants of the expected profitability of carbon capture, subject to uncertainty. The uncertainty surrounding the technical performance and financial variables selected thus far is propagated in a model that calculates the expected profitability of investments in carbon capture and measures risk in terms of variability in expected net returns from these investments. Given the preliminary nature of the results of this prototype, additional work is required to expand the scope of the model to include additional risk factors, additional information on extant and proposed risk factors, the results of a qualitative risk factor elicitation process, and feedback from utilities and other interested parties involved in the carbon capture project. Additional information on proposed distributions of these risk factors will be integrated into a commercial implementation framework for the purpose of a comparative technology investment analysis.« less

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

Konov, V I

The properties of new carbon materials (single-crystal and polycrystalline CVD diamond films and wafers, single-wall carbon nanotubes and graphene) and the prospects of their use as optical elements and devices are discussed. (optical elements of laser devices)

Genome-Wide Identification of Regulatory Elements and Reconstruction of Gene Regulatory Networks of the Green Alga Chlamydomonas reinhardtii under Carbon Deprivation

PubMed Central

Vischi Winck, Flavia; Arvidsson, Samuel; Riaño-Pachón, Diego Mauricio; Hempel, Sabrina; Koseska, Aneta; Nikoloski, Zoran; Urbina Gomez, David Alejandro; Rupprecht, Jens; Mueller-Roeber, Bernd

2013-01-01

The unicellular green alga Chlamydomonas reinhardtii is a long-established model organism for studies on photosynthesis and carbon metabolism-related physiology. Under conditions of air-level carbon dioxide concentration [CO2], a carbon concentrating mechanism (CCM) is induced to facilitate cellular carbon uptake. CCM increases the availability of carbon dioxide at the site of cellular carbon fixation. To improve our understanding of the transcriptional control of the CCM, we employed FAIRE-seq (formaldehyde-assisted Isolation of Regulatory Elements, followed by deep sequencing) to determine nucleosome-depleted chromatin regions of algal cells subjected to carbon deprivation. Our FAIRE data recapitulated the positions of known regulatory elements in the promoter of the periplasmic carbonic anhydrase (Cah1) gene, which is upregulated during CCM induction, and revealed new candidate regulatory elements at a genome-wide scale. In addition, time series expression patterns of 130 transcription factor (TF) and transcription regulator (TR) genes were obtained for cells cultured under photoautotrophic condition and subjected to a shift from high to low [CO2]. Groups of co-expressed genes were identified and a putative directed gene-regulatory network underlying the CCM was reconstructed from the gene expression data using the recently developed IOTA (inner composition alignment) method. Among the candidate regulatory genes, two members of the MYB-related TF family, Lcr1 (Low-CO 2 response regulator 1) and Lcr2 (Low-CO 2 response regulator 2), may play an important role in down-regulating the expression of a particular set of TF and TR genes in response to low [CO2]. The results obtained provide new insights into the transcriptional control of the CCM and revealed more than 60 new candidate regulatory genes. Deep sequencing of nucleosome-depleted genomic regions indicated the presence of new, previously unknown regulatory elements in the C. reinhardtii genome. Our work can serve as a basis for future functional studies of transcriptional regulator genes and genomic regulatory elements in Chlamydomonas. PMID:24224019

Analysis of Wood Structure Connections Using Cylindrical Steel and Carbon Fiber Dowel Pins

NASA Astrophysics Data System (ADS)

Vodiannikov, Mikhail A.; Kashevarova, Galina G., Dr.

2017-06-01

In this paper, the results of the statistical analysis of corrosion processes and moisture saturation of glued laminated timber structures and their joints in corrosive environment are shown. This paper includes calculation results for dowel connections of wood structures using steel and carbon fiber reinforced plastic cylindrical dowel pins in accordance with applicable regulatory documents by means of finite element analysis in ANSYS software, as well as experimental findings. Dependence diagrams are shown; comparative analysis of the results obtained is conducted.

Some chemical aspects of diagenetic carbonates from the Miocene of Sitakund, Bangladesh

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

Akhter, S.H.; Chowdhury, S.Q.; Kandaker, N.I.

1990-05-01

A preliminary chemical and petrological study was done of the Miocene limestone and its comparison with surrounding and overlying marine shales. The material for these studies was obtained from the Miocene Surma sediments exposed in Sitakund region, Cluttagong, Bangladesh. These limestones occur in a predominantly marine shale sequence and show an apparent angular structural relationship with respect to the host marine shales. Three types of carbonates are recognized: banded limestone, dark laminated limestone, and argillaceous limestone. These are devoid of any skeletal remains and often show recrystallization phenomena. Carbonate mineral phases included calcite, aragonite, dolomite, and more rarely magnesite andmore » ankerite. Noncarbonate fraction shows quartz, although very fine grained, is intricately intergrown, indicating that it is at least recrystallized, if not authigenic. Petrographic study of these carbonates show a great variability in terms of texture and composition and suggest a complex multistep and presumably continuous diagenesis. Relatively high REE (rare earth elements) abundances in these carbonates are most likely due to diagenesis and incorporation of mobile REE from local detrital phases into diagenetic carbonates. The anomalously low abundances of cerium in all the carbonates indicates a predominantly marine source for the REE. Recrystallization of carbonate resulted in the extensive exchange of Sr and O between carbonate and diagenetic fluid, the latter being low in REE/Ca ratios. Associated marine shales have quite dissimilar trace-element signatures. This may reflect uncommon crustal sources of REE for the carbonates and clastics. The enrichment of Ni and Zn in marine shales are related to the proximality of local bedrock source areas and clay minerals in the marine sediments.« less

Trace Elements in Calcifying Marine Invertebrates Indicate Diverse Sensitivities to the Seawater Carbonate System

NASA Astrophysics Data System (ADS)

Doss, W. C.

2015-12-01

Surface ocean absorption of anthropogenic CO2 emissions resulting in ocean acidification may interfere with the ability of calcifying marine organisms to biomineralize, since the drop in pH is accompanied by reductions in CaCO3 saturation state. However, recent experiments show that net calcification rates of cultured benthic invertebrate taxa exhibit diverse responses to pCO2-induced changes in saturation state (Ries et al., 2009). Advancement of geochemical tools as biomineralization indicators will enable us to better understand these results and therefore help predict the impacts of ongoing and future decrease in seawater pH on marine organisms. Here we build upon previous work on these specimens by measuring the elemental composition of biogenic calcite and aragonite precipitated in four pCO2 treatments (400; 600; 900; and 2850 ppm). Element ratios (including Sr/Ca, Mg/Ca, Li/Ca, B/Ca, U/Ca, Ba/Ca, Cd/Ca, and Zn/Ca) were analyzed in 18 macro-invertebrate species representing seven phyla (crustacea, cnidaria, echinoidea, rhodophyta, chlorophyta, gastropoda, bivalvia, annelida), then compared to growth rate data and experimental seawater carbonate system parameters: [CO32-], [HCO3-], pH, saturation state, and DIC. Correlations between calcite or aragonite composition and seawater carbonate chemistry are highly taxa-specific, but do not resemble trends observed in growth rate for all species. Apparent carbonate system sensitivities vary widely by element, ranging from strongly correlated to no significant response. Interpretation of these results is guided by mounting evidence for the capacity of individual species to modulate pH and/or saturation state at the site of calcification in response to ambient seawater chemistry. Such biomineralization pathways and strategies in turn likely influence elemental fractionation during CaCO3 precipitation. Ries, J.B., A.L. Cohen, A.L., and D.C. McCorkle (2009), Marine calcifiers exhibit mixed responses to CO2-induced ocean acidification, Geology, 37(12), 1131-1134.

Reconstruction of Late Quaternary Climate in Central Europe - A Comparison of Stable Isotope and Trace Element Variations in Speleothems From Different Cave Systems in Germany.

NASA Astrophysics Data System (ADS)

Nordhoff, P.; Wiegand, B.; Simon, K.; Rosendahl, W.; Hansen, B. T.; Kempe, S.

2003-12-01

Speleothems (stalagmites, stalactites, flowstones) are important archives for Late Quaternary continental climatic and paleo-environmental reconstruction. Speleothems form when calcium carbonate precipitates from solutions seeping into caves hosted e.g. in limestone or dolomite complexes. Information of past climate variability and changes in local environmental conditions can be obtained from signatures of the stable isotopes of oxygen and carbon as well as trace element pattern recorded in speleothems. Reconstruction of paleo-temperature and past environmental conditions from stable isotopes, however, require isotopic equilibrium between the drip water and the precipitating calcium carbonate. Results from Dietzel et al. (1992) and Johnson and Ingram (2001) indicate that the formation of modern travertine and speleothem calcite occurs under isotopic equilibrium. Factors that influence the stable oxygen and carbon isotope composition during speleothem precipitation include e.g. the moisture source and precipitation, photosynthetic pathways, the bedrock proportion, and the drip rate. This often leads to a situation with several variables. However, a specific interpretation is possible when dealing with environments where only one of the factors is dominant, or specific settings are assumed to be invariant, or further proxies like trace element variations help to define the frame conditions during speleothem formation. Concentrations of trace elements (e.g. Sr, Mg) which are co-precipitated with calcite are related to changes in the composition of the solution and strongly depend on the dissolution/precipitation dynamics along drip water flow paths. In a multiproxy approach they are a valuable tool for the interpretation of the recorded stable isotope variations. We present first results from different cave systems located in the Swabian Alps and the Harz Mountains (Germany). Our study includes a high-resolution multiproxy approach, using U/Th-TIMS data, stable oxygen/carbon isotope data, and geochemical compositions of speleothems, covering ages from the Late Pleistocene to the Early Holocene. The results are compared to geochemical data from host rocks, soil zones, cave sediments, drip water compositions, and recent calcium carbonate precipitates. Understanding the response of a cave system to the actual climatic, hydrologic and environmental regimen is a main requirement for the interpretation of "paleo-information" conserved in speleothems in order to lead to a coherent picture of past continental climate dynamics. References: Dietzel M., Usdowski E., and Hoefs J., (1992): Applied Geochemistry 7: 177-184. Johnson, K.R. and Ingram, B.L. (2001): Abstract volume, 4th Internat. Symp. On Applied Isotope Geochemistry, Pacific Groove, USA: 70-72.

Parametrization of environment by geochemistry of the varved clastic and bio- chemogenic lake sediments

NASA Astrophysics Data System (ADS)

Kalugin, Ivan; Darin, Andrey; Babich, Valery; Markovich, Tatiana; Meydan, Feray

2017-04-01

As it well known, recent quantitative estimations of high-resolution environmental variability are based on geochemical records in lake sediments. Naturally, annually laminated sediments (varves) are the best objects for paleoclimatic study, because they allow to investigate seasonal variability for understanding long-term environmental pattern. Also, varved sediments seem to be applied as the model for identification of element-indicators for non-laminated sediments. The XRF scanner on Synchrotron Radiation provides big geochemical dataset for next mathematic treatment, including time series construction. XRF scanning realizes rapid and non-destructive determinations more than 30 trace elements in a range of concentration from 1 up to 10000 ppm in annual layers. That makes sedimentary cores comparable with tree-rings. Geochemical and physicochemical investigation of lake sediments provides basic information to identify geochemical signals with paleoclimate. In general, sediment consists of mineral component, organics and carbonates. The proportions between these components are affected by environmental parameters, because measured element content or their combinations show correlation with meteodata on instrumental time interval. That allows applying geochemical variability to reconstruct the environmental parameters in the form of time series. The proportions between main components are controlled by temperature, atmospheric precipitation, water salinity and other external forcings. So, layered structure of lake bottom sediments and detectable elements content variability both represent a continuous record of environmental history. Element composition and it's climatic response. Bottom sediments represent conditions of physical weathering, temperate bioproductivity and aridity, which concern to mountain lakes within extra tropical zone. The numerical values of the parameters can be computed by software of physical-chemical modeling for gas+water+rock multisystems. Mineral matter responses to runoff. Mineral clastic part is correlated with x-ray density. It includes "clastic" rock-forming - Si, Al , Ti, Fe, Mg, Ca, K and trace elements such as Sr, Rb, Y, Zr, REE etc. Organic component of sediment more reflects temperature by means of productivity in the catchment and waterbody. Organophillic elements are Br, I, U and others soluble elements correlated with organic Carbon or LOI<500oC. Bio-chemogenic component is more characteristic for saline lakes, where Ca-, Mg- and Sr- carbonates precipitated in dependence of temperature, aridity and water salinity. Separate geochemical indicators are directly used for paleo- environmental evaluation. For example, elements with changing valency may be a proxy of outer conditions. Fe is strictly connected with sulfur in sulphide under anoxic conditions. And also Fe forms siderite in carbonate ion saturated, but calcium poor, water in the sedimentation system. Mn-enriched layers, crusts and nodules mark usually a long - term pauses of sedimentation in oxic systems. Mo/Mn ratio is good correlated with anoxic atmosphere. And so on. The work is supported by grants RFBR 16-05-00641, 16-05-00657, 15-55-46001.

Process for producing metal compounds from graphite oxide

NASA Technical Reports Server (NTRS)

Hung, Ching-Cheh (Inventor)

2000-01-01

A process for providing elemental metals or metal oxides distributed on a carbon substrate or self-supported utilizing graphite oxide as a precursor. The graphite oxide is exposed to one or more metal chlorides to form an intermediary product comprising carbon, metal, chloride, and oxygen This intermediary product can be flier processed by direct exposure to carbonate solutions to form a second intermediary product comprising carbon, metal carbonate, and oxygen. Either intermediary product may be further processed: a) in air to produce metal oxide; b) in an inert environment to produce metal oxide on carbon substrate; c) in a reducing environment to produce elemental metal distributed on carbon substrate. The product generally takes the shape of the carbon precursor.

Process for Producing Metal Compounds from Graphite Oxide

NASA Technical Reports Server (NTRS)

Hung, Ching-Cheh (Inventor)

2000-01-01

A process for providing elemental metals or metal oxides distributed on a carbon substrate or self-supported utilizing graphite oxide as a precursor. The graphite oxide is exposed to one or more metal chlorides to form an intermediary product comprising carbon. metal. chloride. and oxygen This intermediary product can be flier processed by direct exposure to carbonate solutions to form a second intermediary product comprising carbon. metal carbonate. and oxygen. Either intermediary product may be further processed: a) in air to produce metal oxide: b) in an inert environment to produce metal oxide on carbon substrate: c) in a reducing environment. to produce elemental metal distributed on carbon substrate. The product generally takes the shape of the carbon precursor.

Scalable File Systems for High Performance Computing Final Report

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

Brandt, S A

2007-10-03

Simulations of mode I interlaminar fracture toughness tests of a carbon-reinforced composite material (BMS 8-212) were conducted with LSDYNA. The fracture toughness tests were performed by U.C. Berkeley. The simulations were performed to investigate the validity and practicality of employing decohesive elements to represent interlaminar bond failures that are prevalent in carbon-fiber composite structure penetration events. The simulations employed a decohesive element formulation that was verified on a simple two element model before being employed to perform the full model simulations. Care was required during the simulations to ensure that the explicit time integration of LSDYNA duplicate the near steady-statemore » testing conditions. In general, this study validated the use of employing decohesive elements to represent the interlaminar bond failures seen in carbon-fiber composite structures, but the practicality of employing the elements to represent the bond failures seen in carbon-fiber composite structures during penetration events was not established.« less

Nitrogen--sulfur--carbon nanocomposites and their application as cathode materials in lithium--sulfur batteries

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

Dai, Sheng; Sun, Xiao-Guang; Guo, Bingkun

The invention is directed in a first aspect to electron-conducting porous compositions comprising an organic polymer matrix doped with nitrogen atoms and having elemental sulfur dispersed therein, particularly such compositions having an ordered framework structure. The invention is also directed to composites of such S/N-doped electron-conducting porous aromatic framework (PAF) compositions, or composites of an S/N-doped mesoporous carbon composition, which includes the S/N-doped composition in admixture with a binder, and optionally, conductive carbon. The invention is further directed to cathodes for a lithium-sulfur battery in which such composites are incorporated.

Corrosion resistant positive electrode for high-temperature, secondary electrochemical cell

DOEpatents

Otto, Neil C.; Warner, Barry T.; Smaga, John A.; Battles, James E.

1983-01-01

The corrosion rate of low carbon steel within a positive electrode of a high-temperature, secondary electrochemical cell that includes FeS as active material is substantially reduced by incorporating therein finely divided iron powder in stoichiometric excess to the amount required to form FeS in the fully charged electrode. The cell typically includes an alkali metal or alkaline earth metal as negative electrode active material and a molten metal halide salt as electrolyte. The excess iron permits use of inexpensive carbon steel alloys that are substantially free of the costly corrosion resistant elements chromium, nickel and molybdenum while avoiding shorten cell life resulting from high corrosion rates.

Corrosion resistant positive electrode for high-temperature, secondary electrochemical cell

DOEpatents

Otto, N.C.; Warner, B.T.; Smaga, J.A.; Battles, J.E.

1982-07-07

The corrosion rate of low carbon steel within a positive electrode of a high-temperature, secondary electrochemical cell that includes FeS as active material is substantially reduced by incorporating therein finely divided iron powder in stoichiometric excess to the amount required to form FeS in the fully charged electrode. The cell typically includes an alkali metal or alkaline earth metal as negative electrode active material and a molten metal halide salt as electrolyte. The excess iron permits use of inexpensive carbon steel alloys that are substantially free of the costly corrosion resistant elements chromium, nickel and molybdenum while avoiding shorten cell life resulting from high corrosion rates.

Implications of elevated CO2 on pelagic carbon fluxes in an Arctic mesocosm study - an elemental mass balance approach

NASA Astrophysics Data System (ADS)

Czerny, J.; Schulz, K. G.; Boxhammer, T.; Bellerby, R. G. J.; Büdenbender, J.; Engel, A.; Krug, S. A.; Ludwig, A.; Nachtigall, K.; Nondal, G.; Niehoff, B.; Silyakova, A.; Riebesell, U.

2013-05-01

Recent studies on the impacts of ocean acidification on pelagic communities have identified changes in carbon to nutrient dynamics with related shifts in elemental stoichiometry. In principle, mesocosm experiments provide the opportunity of determining temporal dynamics of all relevant carbon and nutrient pools and, thus, calculating elemental budgets. In practice, attempts to budget mesocosm enclosures are often hampered by uncertainties in some of the measured pools and fluxes, in particular due to uncertainties in constraining air-sea gas exchange, particle sinking, and wall growth. In an Arctic mesocosm study on ocean acidification applying KOSMOS (Kiel Off-Shore Mesocosms for future Ocean Simulation), all relevant element pools and fluxes of carbon, nitrogen and phosphorus were measured, using an improved experimental design intended to narrow down the mentioned uncertainties. Water-column concentrations of particulate and dissolved organic and inorganic matter were determined daily. New approaches for quantitative estimates of material sinking to the bottom of the mesocosms and gas exchange in 48 h temporal resolution as well as estimates of wall growth were developed to close the gaps in element budgets. However, losses elements from the budgets into a sum of insufficiently determined pools were detected, and are principally unavoidable in mesocosm investigation. The comparison of variability patterns of all single measured datasets revealed analytic precision to be the main issue in determination of budgets. Uncertainties in dissolved organic carbon (DOC), nitrogen (DON) and particulate organic phosphorus (POP) were much higher than the summed error in determination of the same elements in all other pools. With estimates provided for all other major elemental pools, mass balance calculations could be used to infer the temporal development of DOC, DON and POP pools. Future elevated pCO2 was found to enhance net autotrophic community carbon uptake in two of the three experimental phases but did not significantly affect particle elemental composition. Enhanced carbon consumption appears to result in accumulation of dissolved organic carbon under nutrient-recycling summer conditions. This carbon over-consumption effect becomes evident from mass balance calculations, but was too small to be resolved by direct measurements of dissolved organic matter. Faster nutrient uptake by comparatively small algae at high CO2 after nutrient addition resulted in reduced production rates under future ocean CO2 conditions at the end of the experiment. This CO2 mediated shift towards smaller phytoplankton and enhanced cycling of dissolved matter restricted the development of larger phytoplankton, thus pushing the system towards a retention type food chain with overall negative effects on export potential.

Effect of nitric acid treatment on activated carbon derived from oil palm shell

NASA Astrophysics Data System (ADS)

Allwar, Allwar; Hartati, Retno; Fatimah, Is

2017-03-01

The primary object of this work is to study the effect of nitric acid on the porous and morphology structure of activated carbon. Production of activated carbon from oil palm shell was prepared with pyrolysis process at temperature 900°C and by introduction of 10 M nitric acid. Determination of surface area, pore volume and pore size distribution of activated carbon was conducted by the N2 adsorption-desorption isotherm at 77 K. Morphology structure and elemental micro-analysis of activated carbon were estimated by Scanning Electron Microscopy (SEM) and energy dispersive X-ray (EDX), respectively. The result shows that activated carbon after treating with nitric acid proved an increasing porous characteristics involving surface area, pore volume and pore size distribution. It also could remove the contaminants including metals and exhibit an increasing of pores and crevices all over the surface.

Water-quality data for selected stations in the East Everglades, Florida

USGS Publications Warehouse

Waller, Bradley G.

1981-01-01

The results of water-quality samples collected from April 1978 through April 1980 from three canal stations, four marsh stations, and two ground-water stations within the East Everglades, Dade County, Florida, are tabulated in 37 tables. The major categories of parameters analyzed are field measurements, physical characteristics, macronutrients (carbon, nitrogen, and phosphorus), major ions, trace elements, and algae. Chemical data for bulk-precipitation stations within and adjacent to the East Everglades are also given. The parameters analyzed include macronutrients, major ions, and trace elements. The period of record for these stations is October 1977 through April 1980. Bottom material at the canal and marsh stations was collected twice during the investigation. These data include analyses for macronutrients, trace elements, and chlorinated-hydrocarbon insecticides. (USGS)

IMPROVING SOURCE PROFILES AND APPORTIONMENT OF COMBUSTION SOURCES USING THERMAL CARBON FRACTIONS IN MULTIVARIATE RECEPTOR MODELS

EPA Science Inventory

The purpose of this study was to improve combustion source profiles and apportionment of a PM2.5 urban aerosol by using 7 individual organic and elemental carbon thermal fractions in place of total organic and elemental carbon. This study used 3 years (96-99) of speciated data...

Dynamic Response of Functionally Graded Carbon Nanotube Reinforced Sandwich Plate

NASA Astrophysics Data System (ADS)

Mehar, Kulmani; Panda, Subrata Kumar

2018-03-01

In this article, the dynamic response of the carbon nanotube-reinforced functionally graded sandwich composite plate has been studied numerically with the help of finite element method. The face sheets of the sandwich composite plate are made of carbon nanotube- reinforced composite for two different grading patterns whereas the core phase is taken as isotropic material. The final properties of the structure are calculated using the rule of mixture. The geometrical model of the sandwich plate is developed and discretized suitably with the help of available shell element in ANSYS library. Subsequently, the corresponding numerical dynamic responses computed via batch input technique (parametric design language code in ANSYS) of ANSYS including Newmark’s integration scheme. The stability of the sandwich structural numerical model is established through the proper convergence study. Further, the reliability of the sandwich model is checked by comparison study between present and available results from references. As a final point, some numerical problems have been solved to examine the effect of different design constraints (carbon nanotube distribution pattern, core to face thickness ratio, volume fractions of the nanotube, length to thickness ratio, aspect ratio and constraints at edges) on the time-responses of sandwich plate.

Water-quality, bed-sediment, and biological data (October 2012 through September 2013) and statistical summaries of data for streams in the Clark Fork Basin, Montana

USGS Publications Warehouse

Dodge, Kent A.; Hornberger, Michelle I.; Dyke, Jessica

2014-01-01

This report presents the analytical results and quality-assurance data for water-quality, bed-sediment, and biota samples collected at sites from October 2012 through September 2013. Water-quality data include concentrations of selected major ions, trace elements, and suspended sediment. Turbidity and dissolved organic carbon were analyzed for water samples collected at the four sites where seasonal daily values of turbidity were being determined. Daily values of mean suspended-sediment concentration and suspended-sediment discharge were determined for four sites. Bed-sediment data include trace-element concentrations in the fine-grained fraction. Biological data include trace-element concentrations in whole-body tissue of aquatic benthic insects. Statistical sum-maries of water-quality, bed-sediment, and biological data for sites in the upper Clark Fork Basin are provided for the period of record.

Main components of PM10 in an area influenced by a cement plant in Catalonia, Spain: Seasonal and daily variations.

PubMed

Rovira, Joaquim; Sierra, Jordi; Nadal, Martí; Schuhmacher, Marta; Domingo, José L

2018-05-01

Particulate matter (PM) composition has a key role in a wide range of health outcomes, such as asthma, chronic obstructive pulmonary disease, lung cancer, cardiovascular disease, and death, among others. Montcada i Reixac, a municipality located in the Barcelona metropolitan area (Catalonia, Spain), for its location and orography, is an interesting case- study to investigate air pollution. The area is also characterized by the presence of different industrial emission sources, including a cement factory and a large waste management plant, as well as an intense traffic. In this study, PM 10 levels, trace elements, ions, and carbonaceous particles were determined for a long time period (2013-2016) in this highly polluted area. PM 10 samples were collected during six consecutive days in two campaigns (cold and warm) per year. A number of elements (As, Ba, Be, Bi, Ca, Cd, Ce, Co, Cr, Cs, Cu, Dy, Er, Eu, Fe, Ga, Gd, Ge, Hf, Hg, Ho, K, La, Li, Hg, Mg, Mn, Mo, Nb, Nd, Ni, Pb, Pr, Rb, Sb, Sc, Se, Sm, Sn, Sr, Tb, Th, Ti, Tl, U, V, W, Y, Yb, and Zr), ions (Cl - , SO 4 2- , NO 3 - , and NH 4 + ), and carbonaceous content (total carbon, organic plus elemental carbon, and CO 3 2- ), were analysed. These data were used to identify the PM 10 main components: mineral matter, sea spray, secondary inorganic aerosols, organic matter plus elemental carbon, trace elements or indeterminate fraction. Although a clear seasonality (cold vs. warm periods) was found, there were no differences between working days and weekends. Obviously, the cement plant influences the surrounding environment. However, no differences in trace elements related with the cement plant activity (Al, Ca, Ni and V) between weekdays and weekends were noted. However, some traffic-related elements (i.e., Co, Cr, Mn, and Sb) showed significantly higher concentrations in weekdays. Copyright © 2018 Elsevier Inc. All rights reserved.

Fast-quench reactor for hydrogen and elemental carbon production from natural gas and other hydrocarbons

DOEpatents

Detering, Brent A.; Kong, Peter C.

2006-08-29

A fast-quench reactor for production of diatomic hydrogen and unsaturated carbons is provided. During the fast quench in the downstream diverging section of the nozzle, such as in a free expansion chamber, the unsaturated hydrocarbons are further decomposed by reheating the reactor gases. More diatomic hydrogen is produced, along with elemental carbon. Other gas may be added at different stages in the process to form a desired end product and prevent back reactions. The product is a substantially clean-burning hydrogen fuel that leaves no greenhouse gas emissions, and elemental carbon that may be used in powder form as a commodity for several processes.

Hydrogen and elemental carbon production from natural gas and other hydrocarbons

DOEpatents

Detering, Brent A.; Kong, Peter C.

2002-01-01

Diatomic hydrogen and unsaturated hydrocarbons are produced as reactor gases in a fast quench reactor. During the fast quench, the unsaturated hydrocarbons are further decomposed by reheating the reactor gases. More diatomic hydrogen is produced, along with elemental carbon. Other gas may be added at different stages in the process to form a desired end product and prevent back reactions. The product is a substantially clean-burning hydrogen fuel that leaves no greenhouse gas emissions, and elemental carbon that may be used in powder form as a commodity for several processes.

Distribution, movement, and evolution of the volatile elements in the lunar regolith

NASA Technical Reports Server (NTRS)

Gibson, E. K., Jr.

1975-01-01

The abundances and distributions of carbon, nitrogen, and sulfur in lunar soils are reviewed. Carbon and nitrogen have a predominantly extra-lunar origin in lunar soils and breccias, while sulfur is mostly indigeneous to the moon. The lunar processes which effect the movement, distribution, and evolution of carbon, nitrogen, and sulfur, along with the volatile alkali elements sodium, potassium, and rubidium during regolith processes are discussed. Possible mechanisms which may result in the addition to or loss from the moon of these volatile elements are considered.

Qualification of M256 Breechblock Repair Procedure

DTIC Science & Technology

1994-03-01

Percent) Element Chemistry Carbon 0.30/0.40 Silicon 0.15/0.35 Manganese 0.40/0.70 Phosphorus 0.015 max Sulfur 0.015 max Aluminum 0.0 15 max Chromium 1.00...Weld Filler Metal, AWS A&28 Class ER120S.1 (Weight Percent) Element Chemistry Carbon 0.07 Silicon 0.35 Sulfur 0.0008 Phosphorus 0.0006 Chromium 0.45...14OS-l) (Weight Percent) Element Chemistry Carbon 0.11 Silicon 0.35 Sulfur 0.0008 Phosphorus 0.0005 Chromium 0.70 Nickel 2.60 Molybdenum 0.90 Manganese

Advanced NASA Earth Science Mission Concept for Vegetation 3D Structure, Biomass and Disturbance

NASA Technical Reports Server (NTRS)

Ranson, K. Jon

2007-01-01

Carbon in forest canopies represents about 85% of the total carbon in the Earth's aboveground biomass (Olson et al., 1983). A major source of uncertainty in global carbon budgets derives from large errors in the current estimates of these carbon stocks (IPCC, 2001). The magnitudes and distributions of terrestrial carbon storage along with changes in sources and sinks for atmospheric C02 due to land use change remain the most significant uncertainties in Earth's carbon budget. These uncertainties severely limit accurate terrestrial carbon accounting; our ability to evaluate terrestrial carbon management schemes; and the veracity of atmospheric C02 projections in response to further fossil fuel combustion and other human activities. Measurements of vegetation three-dimensional (3D) structural characteristics over the Earth's land surface are needed to estimate biomass and carbon stocks and to quantify biomass recovery following disturbance. These measurements include vegetation height, the vertical profile of canopy elements (i.e., leaves, stems, branches), andlor the volume scattering of canopy elements. They are critical for reducing uncertainties in the global carbon budget. Disturbance by natural phenomena, such as fire or wind, as well as by human activities, such as forest harvest, and subsequent recovery, complicate the quantification of carbon storage and release. The resulting spatial and temporal heterogeneity of terrestrial biomass and carbon in vegetation make it very difficult to estimate terrestrial carbon stocks and quantify their dynamics. Vegetation height profiles and disturbance recovery patterns are also required to assess ecosystem health and characterize habitat. The three-dimensional structure of vegetation provides habitats for many species and is a control on biodiversity. Canopy height and structure influence habitat use and specialization, two fundamental processes that modify species richness and abundance across ecosystems. Accurate and consistent 3D measurements of forest structure at the landscape scale are needed for assessing impacts to animal habitats and biodiversity following disturbance.

Water-quality assessment of part of the upper Mississippi River basin, Minnesota and Wisconsin: Design and implementation of water-quality studies, 1995-98

USGS Publications Warehouse

Stark, James R.; Fallon, J.D.; Fong, A.L.; Goldstein, R.M.; Hanson, P.E.; Kroening, S.E.; Lee, K.E.

1999-01-01

This report describes the design, site-selection, and implementation of the study. Methods used to collect, process, and analyze samples; characterize sites; and assess habitat are described. A comprehensive list of sample sites is provided. Sample analyses for water-quality studies included chlorophyll a, major inorganic constituents, nutrients, trace elements, tritium, radon, environmental isotopes, organic carbon, pesticides, volatile organic compounds, and other synthetic and naturallyoccurring organic compounds. Aquatic-biological samples included fish, benthic macroinvertebrates, and algal enumeration and identification, as well as synthetic-organic compounds and trace elements in fish tissue.

Physical and chemical properties and adsorption type of activated carbon prepared from plum kernels by NaOH activation.

PubMed

Tseng, Ru-Ling

2007-08-25

Activated carbon was prepared from plum kernels by NaOH activation at six different NaOH/char ratios. The physical properties including the BET surface area, the total pore volume, the micropore ratio, the pore diameter, the burn-off, and the scanning electron microscope (SEM) observation as well as the chemical properties, namely elemental analysis and temperature programmed desorption (TPD), were measured. The results revealed a two-stage activation process: stage 1 activated carbons were obtained at NaOH/char ratios of 0-1, surface pyrolysis being the main reaction; stage 2 activated carbons were obtained at NaOH/char ratios of 2-4, etching and swelling being the main reactions. The physical properties of stage 2 activated carbons were similar, and specific area was from 1478 to 1887m(2)g(-1). The results of reaction mechanism of NaOH activation revealed that it was apparently because of the loss ratio of elements C, H, and O in the activated carbon, and the variations in the surface functional groups and the physical properties. The adsorption of the above activated carbons on phenol and three kinds of dyes (MB, BB1, and AB74) were used for an isotherm equilibrium adsorption study. The data fitted the Langmuir isotherm equation. Various kinds of adsorbents showed different adsorption types; separation factor (R(L)) was used to determine the level of favorability of the adsorption type. In this work, activated carbons prepared by NaOH activation were evaluated in terms of their physical properties, chemical properties, and adsorption type; and activated carbon PKN2 was found to have most application potential.

Impacts of exposure to black carbon, elemental carbon, and ultrafine particles from indoor and outdoor sources on blood pressure in adults: A review of epidemiological evidence.

PubMed

Magalhaes, Sandra; Baumgartner, Jill; Weichenthal, Scott

2018-02-01

Ambient particulate air pollution is known to have detrimental effects on cardiovascular health but less is known about the specific effects of black carbon or elemental carbon (BC/EC) and ultrafine particles (UFP). We present a narrative review of the epidemiological evidence related to the impact of exposure to BC/EC and UFP on blood pressure in adults. We searched PubMed and EMBASE in September 2017, using a predefined search strategy. Abstracts were screened using predefined inclusion criteria. Data collection was completed using a standard data extraction form. We focused on main effect estimates for associations between short (≤7 days) and long-term exposures to BC/EC and UFP and systolic (SBP) and diastolic blood pressure (DBP). Effect estimates were rescaled to enable direct comparisons between studies. Thirty publications were included in the review: 19 studies examined outdoor exposure to BC/EC, 11 examined outdoor UFP, three studies examined indoor BC and one study examined indoor UFP. In general, existing evidence supports a positive association between BC/EC and blood pressure. Evidence for outdoor UFP exposures were less clear as effect estimates were small in magnitude and confidence intervals often included the null. Existing evidence supports a positive association between BC/EC and blood pressure in adults, whereas UFPs do not appear to have a meaningful impact on blood pressure. Copyright © 2017 Elsevier Inc. All rights reserved.

Whole watershed quantification of net carbon fluxes by erosion and deposition within the Christina River Basin Critical Zone Observatory

NASA Astrophysics Data System (ADS)

Aufdenkampe, A. K.; Karwan, D. L.; Aalto, R. E.; Marquard, J.; Yoo, K.; Wenell, B.; Chen, C.

2012-12-01

We have proposed that the rate at which fresh, carbon-free minerals are delivered to and mix with fresh organic matter determines the rate of carbon preservation at a watershed scale (Aufdenkampe et al. 2011). Although many studies have examined the role of erosion in carbon balances, none consider that fresh carbon and fresh minerals interact. We believe that this mechanism may be a dominant sequestration process in watersheds with strong anthropogenic impacts. Our hypothesis - that the rate of mixing fresh carbon with fresh, carbon-free minerals is a primary control on watershed-scale carbon sequestration - is central to our Christina River Basin Critical Zone Observatory project (CRB-CZO, http://www.udel.edu/czo/). The Christina River Basin spans 1440 km2 from piedmont to Atlantic coastal plain physiographic provinces in the states of Pennsylvania and Delaware, and experienced intensive deforestation and land use beginning in the colonial period of the USA. Here we present a synthesis of multi-disciplinary data from the CRB-CZO on materials as they are transported from sapprolite to topsoils to colluvium to suspended solids to floodplains, wetlands and eventually to the Delaware Bay estuary. At the heart of our analysis is a spatially-integrated, flux-weighted comparison of the organic carbon to mineral surface area ratio (OC/SA) of erosion source materials versus transported and deposited materials. Because source end-members - such as forest topsoils, farmed topsoils, gullied subsoils and stream banks - represent a wide distribution of initial, pre-erosion OC/SA, we quantify source contributions using geochemical sediment fingerprinting approaches (Walling 2005). Analytes used for sediment fingerprinting include: total mineral elemental composition (including rare earth elements), fallout radioisotope activity for common erosion tracers (beryllium-7, beryllium-10, lead-210, cesium-137), particle size distribution and mineral specific surface area, in addition to organic carbon and nitrogen content with stable isotope (13C, 15N) and radiocarbon (14C) abundance to quantify OC/SA and organic carbon sources and mean age. We then use multivariate mixing model analysis to quantify the fractional contribution of each source end-member to each sample of suspended or deposited sediments. Last, we calculate a predicted OC/SA based on source end-member mixing and compare to the measured OC/SA to quantify net change in mineral complexed carbon.

Bottom-up assessment of the Net Ecosystem Carbon Balance of Russian forests in 2010 for comparison to Top-down estimates.

NASA Astrophysics Data System (ADS)

Maksyutov, S. S.; Shvidenko, A.; Shchepashchenko, D.

2014-12-01

The verified full carbon assessment of Russian forests (FCA) is based on an Integrated Land Information System (ILIS) that includes a multi-layer and multi-scale GIS with basic resolution of 1 km and corresponding attributive databases. The ILIS aggregates all available information about ecosystems and landscapes, sets of empirical and semi-empirical data and aggregations, data of different inventories and surveys, and multi-sensor remote sensing data. The ILIS serves as an information base for application of the landscape-ecosystem approach (LEA) of the FCA and as a systems design for comparison and mutual constraints with other methods of study of carbon cycling of forest ecosystems (eddy covariance; process models; inverse modeling; and multi-sensor application of remote sensing). The LEA is based on a complimentary use of the flux-based method with some elements of the pool-based method. Introduction of climatic parameters of individual years in the LEA, as well as some process-based elements, allows providing a substantial decrease of the uncertainties of carbon cycling yearly indicators of forest ecosystems. Major carbon pools (live biomass, coarse woody debris, soil organic carbon) are estimated based on data on areas, distribution and major biometric characteristics of Russian forests presented in form of the ILIS for the country. The major fluxes accounted for include Net Primary Production (NPP), Soil Heterotrophic Respiration (SHR), as well as fluxes caused by decomposition of Coarse Woody Debris (CWD), harvest and use of forest products, fluxes caused by natural disturbances (fire, insect outbreaks, impacts of unfavorable environment) and lateral fluxes to hydrosphere and lithosphere. Use of landscape-ecosystem approach resulted in the NECB at 573±140 Tg C yr-1 (CI 0.9). While the total carbon sink is high, large forest areas, particularly on permafrost, serve as a carbon source. The ratio between net primary production and soil heterotrophic respiration, together with natural and human-induced disturbances are major drivers of the magnitude and spatial distribution of the NECB of forest ecosystems. We also present comparison to the recent top-down estimates of the Siberian carbon sink.

Graphite-based photovoltaic cells

DOEpatents

Lagally, Max; Liu, Feng

2010-12-28

The present invention uses lithographically patterned graphite stacks as the basic building elements of an efficient and economical photovoltaic cell. The basic design of the graphite-based photovoltaic cells includes a plurality of spatially separated graphite stacks, each comprising a plurality of vertically stacked, semiconducting graphene sheets (carbon nanoribbons) bridging electrically conductive contacts.

Ambient Air Pollution and Increases in Blood Pressure: Role for biological constituents of particulate matter

EPA Science Inventory

Particulate matter (PM) is a complex mixture of extremely small particles and liquid droplets made up of a number of components including elemental carbon, organic chemicals, metals, acids (such as nitrates and sulfates), and soil and dust particles. Epidemiological studies con...

PM2.5 Emission Elemental Composition from Diverse Combustion Sources in the Metropolitan Area of Mexico City

PubMed Central

Mugica, V.; Mugica, F.; Torres, M.; Figueroa, J.

2008-01-01

A field study was carried out from 2003 to 2004 with the aim to develop the PM2.5 emission source profiles from light-duty gasoline and heavy-duty diesel vehicles, as well as emission source profiles from waste incineration, wood burning, LP gas combustion, and meat broiling. Over 25 chemical species were quantified from the fine particles emitted by the different combustion sources investigated, including organic and elemental carbon, ions, and elements. The OC/TC ratio found in the different PM2.5 profiles was dissimilar as well as the sulfate, nitrate, ammonium, soil species, and trace element content. Consequently, these combustion emission profiles could be used in source reconciliation studies for fine particles. PMID:18379705

Chemical composition of PM2.5 at an urban site of Chengdu in southwestern China

NASA Astrophysics Data System (ADS)

Tao, Jun; Cheng, Tiantao; Zhang, Renjian; Cao, Junji; Zhu, Lihua; Wang, Qiyuan; Luo, Lei; Zhang, Leiming

2013-07-01

PM2.5 aerosols were sampled in urban Chengdu from April 2009 to January 2010, and their chemical compositions were characterized in detail for elements, water soluble inorganic ions, and carbonaceous matter. The annual average of PM2.5 was 165 μg m-3, which is generally higher than measurements in other Chinese cities, suggesting serious particulate pollution issues in the city. Water soluble ions contributed 43.5% to the annual total PM2.5 mass, carbonaceous aerosols including elemental carbon and organic carbon contributed 32.0%, and trace elements contributed 13.8%. Distinct daily and seasonal variations were observed in the mass concentrations of PM2.5 and its components, reflecting the seasonal variations of different anthropogenic and natural sources. Weakly acidic to neutral particles were found for PM2.5. Major sources of PM2.5 identified from source apportionment analysis included coal combustion, traffic exhaust, biomass burning, soil dust, and construction dust emissions. The low nitrate: sulfate ratio suggested that stationary emissions were more important than vehicle emissions. The reconstructed masses of ammonium sulfate, ammonium nitrate, particulate carbonaceous matter, and fine soil accounted for 79% of the total measured PM2.5 mass; they also accounted for 92% of the total measured particle scattering.

A combined experimental and finite element study to predict the failure mechanisms in SiC coated carbon/carbon composites at room and elevated temperatures under flexural loading

NASA Technical Reports Server (NTRS)

Mahfuz, Hassan; Das, Partha S.; Xue, Dongwei; Krishnagopalan, Jaya; Jeelani, Shaik

1993-01-01

Response of quasi-isotropic laminates of SiC coated Carbon/Carbon (C/C) composites have been investigated under flexural loading at various temperatures. Variation of load-deflection behavior with temperatures are studied. Increase in flexural strength and stiffness are observed with the rise in temperature. Extensive analyses through Optical Microscope (OM) and Non-Destructive Evaluation (NDE) have been performed to understand the failure mechanisms. Damage zone is found only within the neighborhood of the loading plane. Isoparametric layered shell elements developed on the basis of the first order shear deformation theory have been used to model the thin laminates of C/C under flexural loading. Large deformation behavior has been considered in the finite element analysis to account for the non-linearities encountered during the actual test. Data generated using finite element analysis are presented to corroborate the experimental findings, and a comparison in respect of displacement and stress-strain behavior are given to check the accuracy of the finite element analysis. Reasonable correlation between the experimental and finite element results have been established.

Distribution of radionuclides during melting of carbon steel

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

Thurber, W.C.; MacKinney, J.

1997-02-01

During the melting of steel with radioactive contamination, radionuclides may be distributed among the metal product, the home scrap, the slag, the furnace lining and the off-gas collection system. In addition, some radionuclides will pass through the furnace system and vent to the atmosphere. To estimate radiological impacts of recycling radioactive scrap steel, it is essential to understand how radionuclides are distributed within the furnace system. For example, an isotope of a gaseous element (e.g., radon) will exhaust directly from the furnace system into the atmosphere while a relatively non-volatile element (e.g., manganese) can be distributed among all the othermore » possible media. This distribution of radioactive contaminants is a complex process that can be influenced by numerous chemical and physical factors, including composition of the steel bath, chemistry of the slag, vapor pressure of the particular element of interest, solubility of the element in molten iron, density of the oxide(s), steel melting temperature and melting practice (e.g., furnace type and size, melting time, method of carbon adjustment and method of alloy additions). This paper discusses the distribution of various elements with particular reference to electric arc furnace steelmaking. The first two sections consider the calculation of partition ratios for elements between metal and slag based on thermodynamic considerations. The third section presents laboratory and production measurements of the distribution of various elements among slag, metal, and the off-gas collection system; and the final section provides recommendations for the assumed distribution of each element of interest.« less

Mass absorption efficiency of elemental carbon over Van Vihar National Park, Bhopal, India: Temporal variability and implications to estimates of black carbon radiative forcing

NASA Astrophysics Data System (ADS)

Samiksha, S.; Raman, R. S.; Singh, A.

2016-12-01

It is now well recognized that black carbon (a component of aerosols that is similar but not identical to elemental carbon) is an important contributor to global warming, second only to CO2.However, the most popular methods for estimation of black carbon rely on accurate estimates of its mass absorption efficiency (MAE) to convert optical attenuation measurements to black carbon concentrations. Often a constant manufacturer specified MAE is used for this purposes. Recent literature has unequivocally established that MAE shows large spatio-temporal heterogeneities. This is so because MAE depends on emission sources, chemical composition, and mixing state of aerosols. In this study, ambient PM2.5 samples were collected over an ecologically sensitive zone (Van Vihar National Park) in Bhopal, Central India for two years (01 January, 2012 to 31 December, 2013). Samples were collected on Teflon, Nylon, and Tissue quartz filter substrates. Punches of quartz fibre filter were analysed for organic and elemental carbon (OC/EC) by a thermal-optical-transmittance/reflectance (TOT-TOR) analyser operating with a 632 nm laser diode. Teflon filters were also used to interdependently measure PM2.5 attenuation (at 370 nm and 800 nm) by transmissometry. Site-specific mass absorption efficiency (MAE) for elemental carbon over the study site will be derived using a combination of measurements from the TOT/TOR analyser and transmissometer. An assessment of site-specific MAE values, its temporal variability and implications to black carbon radiative forcing will be discussed. It is now well recognized that black carbon (a component of aerosols that is similar but not identical to elemental carbon) is an important contributor to global warming, second only to CO2. However, the most popular methods for estimation of black carbon rely on accurate estimates of its mass absorption efficiency (MAE) to convert optical attenuation measurements to black carbon concentrations. Often a constant manufacturer specified MAE is used for this purposes. Recent literature has unequivocally established that MAE shows large spatio-temporal heterogeneities. This is so because MAE depends on emission sources, chemical composition, and mixing state of aerosols. In this study, ambient PM2.5 samples were collected over an ecologically sensitive zone (Van Vihar National Park) in Bhopal, Central India for two years (01 January, 2012 to 31 December, 2013). Samples were collected on Teflon, Nylon, and Tissue quartz filter substrates. Punches of quartz fibre filter were analysed for organic and elemental carbon (OC/EC) by a thermal-optical-transmittance/reflectance (TOT-TOR) analyser operating with a 632 nm laser diode. Teflon filters were also used to interdependently measure PM2.5 attenuation (at 370 nm and 800 nm) by transmissometry. Site-specific mass absorption efficiency (MAE) for elemental carbon over the study site will be derived using a combination of measurements from the TOT/TOR analyser and transmissometer. An assessment of site-specific MAE values, its temporal variability and implications to black carbon radiative forcing will be discussed.

Direct carbon fuel cell and stack designs

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

Gorte, Raymond J.; Oh, Tae-Sik

Disclosed are novel configurations of Direct Carbon Fuel Cells (DCFCs), which optionally comprise a liquid anode. The liquid anode comprises a molten salt/metal, preferably Sb, and a fuel, which has significant elemental carbon content (coal, bio-mass, etc.). The supply of fuel is continuously replenished in the anode. In addition, a stack configuration is suggested where combining a large number of planar or tubular fuel elements.

Technical note: Aerosol light absorption measurements with a carbon analyser - Calibration and precision estimates

NASA Astrophysics Data System (ADS)

Ammerlaan, B. A. J.; Holzinger, R.; Jedynska, A. D.; Henzing, J. S.

2017-09-01

Equivalent Black Carbon (EBC) and Elemental Carbon (EC) are different mass metrics to quantify the amount of combustion aerosol. Both metrics have their own measurement technique. In state-of-the-art carbon analysers, optical measurements are used to correct for organic carbon that is not evolving because of pyrolysis. These optical measurements are sometimes used to apply the technique of absorption photometers. Here, we use the transmission measurements of our carbon analyser for simultaneous determination of the elemental carbon concentration and the absorption coefficient. We use MAAP data from the CESAR observatory, the Netherlands, to correct for aerosol-filter interactions by linking the attenuation coefficient from the carbon analyser to the absorption coefficient measured by the MAAP. Application of the calibration to an independent data set of MAAP and OC/EC observations for the same location shows that the calibration is applicable to other observation periods. Because of simultaneous measurements of light absorption properties of the aerosol and elemental carbon, variation in the mass absorption efficiency (MAE) can be studied. We further show that the absorption coefficients and MAE in this set-up are determined within a precision of 10% and 12%, respectively. The precisions could be improved to 4% and 8% when the light transmission signal in the carbon analyser is very stable.

Nitrogen-assisted Three-phase Equilibrium in Hydrate Systems Composed of Water, Methane, Carbon Dioxide, and Nitrogen

NASA Astrophysics Data System (ADS)

Darnell, K.; Flemings, P. B.; DiCarlo, D. A.

2016-12-01

In June 2016, seawater samples at sediment-seawater interface and sediment samples were collected by the he Jiaolong, China's manned submersible, at four sampling sites located in the Yap Trench. Seawater samples from different depths of the trench were also collected by CTD. Chemical parameters, including pH, alkanility, concentrations of dissolved inorganic carbon, dissolved and total organic carbon, methane, dimethylsulfoniopropionate, nutrients, carbohydrates, and amino acids were analyzed in the seawater samples. Concentrations of total organic carbon, six constant elements and nine trace elements were determined in the sediment samples. All the vertical profiles of the chemical parameters in the seawater have unique characteristics. Our resluts also showed that the carbonate compensation depth (CCD) was between 4500 m and 5000 m in the trench. The hadal sediment at 6500 m depth under the CCD line was siliceous ooze favored for the burial of orgaic carbon, attributed to accumulation of surface sediment by gravity flow. The abyssal sediment at the 4500 m depth was calcareous ooze. Various microfossils, such as discoasters and diatoms, were identified in different sediment layers of the sediment samples.Based on the ratios of Fe/Al and Ti/Al, and the correlation between different elements, the sediment in the Yap Trench were derived from biogenic, terrestrial, volcanic and autogenic sources. The ratios of Ni/Co and V/Cr showed that the deposition environment of the trench should be oxidative, arributed to inflow of the Antractic bottom oxygen-rich seawater.The high concentraiont of Ca in the sediment from the station 371-Yap-S02 below 4 cm depth indicated that there was no large-scale volcanic eruption in the research area and the volcanic materials in the sediment might orginated from the Mariana Volcanic Arc, and the Carolyn Ridge has been slowly sinking on the east side of the trench due to plate subduction. This study is the first systematic study of chemical characteristics in the seawater and sediment of the Yap Trench.

A comparative study on effects of heterotrophic microbial activity on the stability of bivalve and coral carbonate during early diagenesis.

NASA Astrophysics Data System (ADS)

Lange, Skadi M.; Krause, Stefan; Immenhauser, Adrian; Ritter, Ann-Christin; Gorb, Stanislav N.; Kleinteich, Thomas; Treude, Tina

2016-04-01

Following deposition and shallow burial, marine biogenic carbonates are exposed to an environment that is geochemically affected by a manifold of bacterial metabolic redox processes. To allow for comparison of potential microbe-mediated alteration effects on carbonates, we used aragonitic bivalve shell samples and porous aragonitic coral fragments for incubation experiments in oxic- and anoxic seawater media. The media contained marine sediment slurries or bacterial cultures to mimic the natural processes in vitro. The results for anoxic experimental media containing bivalve shell samples or coral fragments displayed considerable changes in carbonate-system parameters (pH, AT, CA, DIC) and divalent-cation ratios (Mg/Ca, Mg/Sr, Sr/Ca) over time. Furthermore, incubated bivalve shell samples were altered in morphology, elemental composition and isotopic signature. Coral-fragment bearing oxic incubations were run at two temperature regimes and divalent-cation ratios of the high-temperature bacterial medium displayed withdrawal of Ca2+ and Sr2+ from the medium, thus indicating microbe-induced secondary aragonite precipitation. Analyses of coral fragments include electron-microprobe mapping and X-ray microtomography to resolve elemental sample composition and pore-space alteration features, respectively. Up to this point our results indicate that heterotrophic bacterial activity has the potential to affect surficial or open pore space in carbonate archives by increasing rates of alteration relative to sterile environments.

Explicit Pore Pressure Material Model in Carbon-Cloth Phenolic

NASA Technical Reports Server (NTRS)

Gutierrez-Lemini, Danton; Ehle, Curt

2003-01-01

An explicit material model that uses predicted pressure in the pores of a carbon-cloth phenolic (CCP) composite has been developed. This model is intended to be used within a finite-element model to predict phenomena specific to CCP components of solid-fuel-rocket nozzles subjected to high operating temperatures and to mechanical stresses that can be great enough to cause structural failures. Phenomena that can be predicted with the help of this model include failures of specimens in restrained-thermal-growth (RTG) tests, pocketing erosion, and ply lifting

Chemical Oceanography and the Marine Carbon Cycle

NASA Astrophysics Data System (ADS)

Emerson, Steven; Hedges, John

The principles of chemical oceanography provide insight into the processes regulating the marine carbon cycle. The text offers a background in chemical oceanography and a description of how chemical elements in seawater and ocean sediments are used as tracers of physical, biological, chemical and geological processes in the ocean. The first seven chapters present basic topics of thermodynamics, isotope systematics and carbonate chemistry, and explain the influence of life on ocean chemistry and how it has evolved in the recent (glacial-interglacial) past. This is followed by topics essential to understanding the carbon cycle, including organic geochemistry, air-sea gas exchange, diffusion and reaction kinetics, the marine and atmosphere carbon cycle and diagenesis in marine sediments. Figures are available to download from www.cambridge.org/9780521833134. Ideal as a textbook for upper-level undergraduates and graduates in oceanography, environmental chemistry, geochemistry and earth science and a valuable reference for researchers in oceanography.

Biogeochemical cycles of carbon, sulfur, and free oxygen in a microbial mat

NASA Astrophysics Data System (ADS)

Canfield, Donald E.; Des Marais, David J.

1993-08-01

Complete budgets for carbon and oxygen have been constructed for cyanobacterial mats dominated by Microcoleus chthonoplastes from the evaporating ponds of a salt works located in Guerrero Negro, Baja California Sur, Mexico. Included in the budget are measured rates of O 2 production, sulfate reduction, and elemental exchange across the mat/brine interface, day and night, at various temperatures and times of the year. We infer from this data the various sinks for O 2, as well as the sources of carbon for primary production. To summarize, although seasonal variability exists, a major percentage of the O 2 produced during the day did not diffuse out of the mat but was used within the mat to oxidize both organic carbon and the sulfide produced by sulfate reduction. At night, most of the O 2 that diffused into the mat was used to oxidize sulfide, with O 2 respiration of minor importance. During the day, the internal mat processes of sulfate reduction and O 2 respiration generated as much or more inorganic carbon (DIC) for primary production as diffusion into the mat. Also, oxygenic photosynthesis was the most important process of carbon fixation, although anoxygenic photosynthesis may have been important at low light levels during some times of the year. At night, the DIC lost from the mat was mostly from sulfate reduction. Elemental fluxes across the mat/brine interface indicated that carbon with an oxidation state of greater than zero was taken up by the mat during the day and liberated from the mat at night. Overall, carbon with an average oxidation state of near zero accumulated in the mat. Both carbon fixation and carbon oxidation rates varied with temperature by a similar amount. These mats are thus closely coupled systems where rapid rates of photosynthesis both require and fuel rapid rates of heterotrophic carbon oxidation.

Interface Analyses Between a Case-Hardened Ingot Casting Steel and Carbon-Containing and Carbon-Free Refractories

NASA Astrophysics Data System (ADS)

Fruhstorfer, Jens; Dudczig, Steffen; Rudolph, Martin; Schmidt, Gert; Brachhold, Nora; Schöttler, Leandro; Rafaja, David; Aneziris, Christos G.

2018-06-01

Corrosion tests of carbon-free and carbon-containing refractories were performed. The carbon-free crucibles corroded, whereas the carbon-containing crucibles were negligibly attacked. On them, inclusions were attached. This study investigates melt oxygen contents, interface properties, and steel compositions with their non-metallic inclusions in order to explore the inclusion formation and deposition mechanisms. The carbon-free crucibles were based on alumina, mullite, and zirconia- and titania-doped alumina (AZT). The carbon-containing (-C) ones were alumina-C and AZT-C. Furthermore, nanoscaled carbon and alumina additives (-n) were applied in an AZT-C-n material. In the crucibles, the case-hardened steel 17CrNiMo7-6 was remelted at 1580 °C. It was observed that the melt and steel oxygen contents were higher for the tests in the carbon-free crucibles. Into these crucibles, the deoxidizing alloying elements Mn and Si diffused. Reducing contents of deoxidizing elements resulted in higher steel oxygen levels and less inclusions, mainly of the inclusion group SiO2-core-MnS-shell (2.5 to 8 μ m). These developed from smaller SiO2 nuclei. The inclusion amount in the steel was highest after remelting in AZT-C-n for 30 minutes but decreased strongly with increasing remelting time (60 minutes) due to inclusions' deposition on the refractory surface. The Ti from the AZT and the nanoadditives supported inclusion growth and deposition. Other inclusion groups were alumina and calcium aluminate inclusions. Their contents were high after remelting in carbon- or AZT-containing crucibles but generally decreased during remelting. On the AZT-C-n crucible, a dense layer formed from vitreous compositions including Al, Ca, Mg, Si, and Ti. To summarize, for reducing forming inclusion amounts, mullite is recommended as refractory material. For capturing formed inclusions, AZT-C-n showed a high potential.

Geochemical and mineralogical controls on metal(loid) mobility in the oxide zone of the Prairie Creek Deposit, NWT

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

Stavinga, Drew; Jamieson, Heather; Layton-Matthews, Daniel

2017-02-01

Prairie Creek is an unmined high grade Zn-Pb-Ag deposit in the southern Mackenzie Mountains of the Northwest Territories, located in a 320 km2 enclave surrounded by the Nahanni National Park reserve. The upper portion of the quartz-carbonate-sulphide vein mineralization has undergone extensive oxidation, forming high grade zones, rich in smithsonite (ZnCO3) and cerussite (PbCO3). This weathered zone represents a significant resource and a potential component of mine waste material. This study is focused on characterizing the geochemical and mineralogical controls on metal(loid) mobility under mine waste conditions, with particular attention to the metal carbonates as a potential source of tracemore » elements to the environment. Analyses were conducted using a combination of microanalytical techniques (electron microprobe, scanning electron microscopy with automated mineralogy, laser-ablation inductively-coupled mass spectrometry, and synchrotron-based element mapping, micro-X-ray diffraction and micro-X-ray absorbance). The elements of interest included Zn, Pb, Ag, As, Cd, Cu, Hg, Sb and Se.« less

Chemical and stable carbon isotopic composition of PM2.5 from on-road vehicle emissions in the PRD region and implication for vehicle emission control policy

NASA Astrophysics Data System (ADS)

Dai, S.; Bi, X.; Chan, L. Y.; He, J.; Wang, B.; Wang, X.; Sheng, G.; Fu, J.

2014-11-01

Vehicle emission is a major source of urban air pollution. In recent decade, the Chinese government has introduced a range of policies to reduce the vehicle emission. In order to understand the chemical characteristics of PM2.5 from on-road vehicle emission in the Pearl River Delta (PRD) region and to evaluate the effectiveness of control policies on vehicles emission, the emission factors of PM2.5 mass, elemental carbon (EC), organic carbon (OC), water-soluble organic carbon (WSOC), water-soluble inorganic ions (WSII), metal elements, organic compounds and stable carbon isotopic composition were measured in the Zhujiang Tunnel of Guangzhou, the PRD region of China in 2013. Emission factors of PM2.5 mass, OC, EC, and WSOC were 92.4, 16.7, 16.4, and 1.31 mg vehicle-1 km-1 respectively. Emission factors of WSII were 0.016 (F-) ~4.17 (Cl-) mg vehicle-1 km-1, totally contributing about 9.8% to the PM2.5 emissions. The sum of 27 measured metal elements accounted for 15.2% of the PM2.5 emissions. Fe was the most abundant metal element, with an emission factor of 3.91 mg vehicle-1 km-1. Emission factors of organic compounds including n-alkanes, PAHs, hopanes, and steranes were 91.9, 5.02, 32.0 and 7.59 μg vehicle-1 km-1, respectively. Stable carbon isotopic composition δ13C value was measured and it was -25.0‰ on average. An isotopic fractionation of 3.2‰ was found during fuel combustion. Compared with a previous study in Zhujiang Tunnel in year 2004, emission factors of PM2.5 mass, EC, OC, WSII except Cl-, and organic compounds decreased by 16.0-93.4%, which could be attributed to emission control policy from 2004 to 2013. However, emission factors of most of the metal elements increased significantly, which could be partially attributed to the changes in motor oil additives and vehicle condition. There are no mandatory national standards to limit metal content from vehicle emission, which should be a concern of the government. A snapshot of the 2013 characteristic emission of PM2.5 and its constituents from on-road vehicular fleet in the PRD region retrieved from our study was found to be useful for the assessment of past and future implementation of vehicle emission control policy.

Chemical and stable carbon isotopic composition of PM2.5 from on-road vehicle emissions in the PRD region and implications for vehicle emission control policy

NASA Astrophysics Data System (ADS)

Dai, S.; Bi, X.; Chan, L. Y.; He, J.; Wang, B.; Wang, X.; Peng, P.; Sheng, G.; Fu, J.

2015-03-01

Vehicle emissions are a major source of urban air pollution. In recent decade, the Chinese government has introduced a range of policies to reduce vehicle emissions. In order to understand the chemical characteristics of PM2.5 from on-road vehicle emissions in the Pearl River Delta (PRD) region and to evaluate the effectiveness of control policies on vehicle emissions, the emission factors of PM2.5 mass, elemental carbon (EC), organic carbon (OC), water-soluble organic carbon (WSOC), water-soluble inorganic ions (WSII), metal elements, organic compounds and stable carbon isotopic composition were measured in the Zhujiang tunnel of Guangzhou, in the PRD region of China in 2013. Emission factors of PM2.5 mass, OC, EC and WSOC were 92.4, 16.7, 16.4 and 1.31 mg vehicle-1 km-1 respectively. Emission factors of WSII were 0.016 (F-) ~ 4.17 (Cl-) mg vehicle-1 km-1, contributing about 9.8% to the PM2.5 emissions. The sum of 27 measured metal elements accounted for 15.2% of PM2.5 emissions. Fe was the most abundant metal element, with an emission factor of 3.91 mg vehicle-1 km-1. Emission factors of organic compounds including n-alkanes, polycyclic aromatic hydrocarbons, hopanes and steranes were 91.9, 5.02, 32.0 and 7.59 μg vehicle-1 km-1, respectively. Stable carbon isotopic composition δ13C value was -25.0‰ on average. An isotopic fractionation of 3.2‰ was found during fuel combustion. Compared to a previous study in Zhujiang tunnel in 2004, emission factors of PM2.5mass, EC, OC, WSII except Cl- and organic compounds decreased by 16.0 ~ 93.4%, which could be attributed to emission control policy from 2004 to 2013. However, emission factors of most of the metal elements increased significantly, which could be partially attributed to the changes in motor oil additives and vehicle conditions. There are no mandatory national standards to limit metal content from vehicle emissions, which should be a concern of the government. A snapshot of the 2013 characteristic emissions of PM2.5 and its constituents from the on-road vehicular fleet in the PRD region retrieved from our study would be helpful for the assessment of past and future implementations of vehicle emission control policy.

Role of Soil Erosion in Biogeochemical Cycling of Essential Elements: Carbon, Nitrogen, and Phosphorus

NASA Astrophysics Data System (ADS)

Berhe, Asmeret Asefaw; Barnes, Rebecca T.; Six, Johan; Marín-Spiotta, Erika

2018-05-01

Most of Earth's terrestrial surface is made up of sloping landscapes. The lateral distribution of topsoil by erosion controls the availability, stock, and persistence of essential elements in the terrestrial ecosystem. Over the last two decades, the role of soil erosion in biogeochemical cycling of essential elements has gained considerable interest from the climate, global change, and biogeochemistry communities after soil erosion and terrestrial sedimentation were found to induce a previously unaccounted terrestrial sink for atmospheric carbon dioxide. More recent studies have highlighted the role of erosion in the persistence of organic matter in soil and in the biogeochemical cycling of elements beyond carbon . Here we synthesize available knowledge and data on how erosion serves as a major driver of biogeochemical cycling of essential elements. We address implications of erosion-driven changes in biogeochemical cycles on the availability of essential elements for primary production, on the magnitude of elemental exports downstream, and on the exchange of greenhouse gases from the terrestrial ecosystem to the atmosphere. Furthermore, we explore fates of eroded material and how terrestrial mass movement events play major roles in modifying Earth's climate.

Electrocatalysts for carbon dioxide conversion

DOEpatents

Masel, Richard I; Salehi-Khojin, Amin

2015-04-21

Electrocatalysts for carbon dioxide conversion include at least one catalytically active element with a particle size above 0.6 nm. The electrocatalysts can also include a Helper Catalyst. The catalysts can be used to increase the rate, modify the selectivity or lower the overpotential of electrochemical conversion of CO.sub.2. Chemical processes and devices using the catalysts also include processes to produce CO, HCO.sup.-, H.sub.2CO, (HCO.sub.2).sup.-, H.sub.2CO.sub.2, CH.sub.3OH, CH.sub.4, C.sub.2H.sub.4, CH.sub.3CH.sub.2OH, CH.sub.3COO.sup.-, CH.sub.3COOH, C.sub.2H.sub.6, (COOH).sub.2, or (COO.sup.-).sub.2, and a specific device, namely, a CO.sub.2 sensor.

Improving source identification of Atlanta aerosol using temperature resolved carbon fractions in positive matrix factorization

NASA Astrophysics Data System (ADS)

Kim, Eugene; Hopke, Philip K.; Edgerton, Eric S.

Daily integrated PM 2.5 (particulate matter ⩽2.5 μm in aerodynamic diameter) composition data including eight individual carbon fractions collected at the Jefferson Street monitoring site in Atlanta were analyzed with positive matrix factorization (PMF). Particulate carbon was analyzed using the thermal optical reflectance method that divides carbon into four organic carbon (OC), pyrolized organic carbon (OP), and three elemental carbon (EC) fractions. A total of 529 samples and 28 variables were measured between August 1998 and August 2000. PMF identified 11 sources in this study: sulfate-rich secondary aerosol I (50%), on-road diesel emissions (11%), nitrate-rich secondary aerosol (9%), wood smoke (7%), gasoline vehicle (6%), sulfate-rich secondary aerosol II (6%), metal processing (3%), airborne soil (3%), railroad traffic (3%), cement kiln/carbon-rich (2%), and bus maintenance facility/highway traffic (2%). Differences from previous studies using only the traditional OC and EC data (J. Air Waste Manag. Assoc. 53(2003a)731; Atmos Environ. (2003b)) include four traffic-related combustion sources (gasoline vehicle, on-road diesel, railroad, and bus maintenance facility) containing carbon fractions whose abundances were different between the various sources. This study indicates that the temperature resolved fractional carbon data can be utilized to enhance source apportionment study, especially with respect to the separation of diesel emissions from gasoline vehicle sources. Conditional probability functions using surface wind data and identified source contributions aid the identifications of local point sources.

Characterization of elemental and structural composition of corrosion scales and deposits formed in drinking water distribution systems.

PubMed

Peng, Ching-Yu; Korshin, Gregory V; Valentine, Richard L; Hill, Andrew S; Friedman, Melinda J; Reiber, Steve H

2010-08-01

Corrosion scales and deposits formed within drinking water distribution systems (DWDSs) have the potential to retain inorganic contaminants. The objective of this study was to characterize the elemental and structural composition of extracted pipe solids and hydraulically-mobile deposits originating from representative DWDSs. Goethite (alpha-FeOOH), magnetite (Fe(3)O(4)) and siderite (FeCO(3)) were the primary crystalline phases identified in most of the selected samples. Among the major constituent elements of the deposits, iron was most prevalent followed, in the order of decreasing prevalence, by sulfur, organic carbon, calcium, inorganic carbon, phosphorus, manganese, magnesium, aluminum and zinc. The cumulative occurrence profiles of iron, sulfur, calcium and phosphorus for pipe specimens and flushed solids were similar. Comparison of relative occurrences of these elements indicates that hydraulic disturbances may have relatively less impact on the release of manganese, aluminum and zinc, but more impact on the release of organic carbon, inorganic carbon, and magnesium. (c) 2010 Elsevier Ltd. All rights reserved.

Radio-frequency and microwave load comprising a carbon-bonded carbon fiber composite

DOEpatents

Lauf, R.J.; McMillan, A.D.; Johnson, A.C.; Everleigh, C.A.; Moorhead, A.J.

1998-04-21

A billet of low-density carbon-bonded carbon fiber (CBCF) composite is machined into a desired attenuator or load element shape (usually tapering). The CBCF composite is used as a free-standing load element or, preferably, brazed to the copper, brass or aluminum components of coaxial transmission lines or microwave waveguides. A novel braze method was developed for the brazing step. The resulting attenuator and/or load devices are robust, relatively inexpensive, more easily fabricated, and have improved performance over conventional graded-coating loads. 9 figs.

Radio-frequency and microwave load comprising a carbon-bonded carbon fiber composite

DOEpatents

Lauf, Robert J.; McMillan, April D.; Johnson, Arvid C.; Everleigh, Carl A.; Moorhead, Arthur J.

1998-01-01

A billet of low-density carbon-bonded carbon fiber (CBCF) composite is machined into a desired attenuator or load element shape (usually tapering). The CBCF composite is used as a free-standing load element or, preferably, brazed to the copper, brass or aluminum components of coaxial transmission lines or microwave waveguides. A novel braze method was developed for the brazing step. The resulting attenuator and/or load devices are robust, relatively inexpensive, more easily fabricated, and have improved performance over conventional graded-coating loads.

Preliminary investigation of the elemental variation and diagenesis of a tabular uranium deposit, La Sal Mine, San Juan County, Utah

USGS Publications Warehouse

Brooks, Robert A.; Campbell, John A.

1976-01-01

Ore in the La Sal mine, San Juan County, Utah, occurs as a typical tabular-type uranium deposit of the-Colorado Plateau. Uranium-vanadium occurs in the Salt Wash Member of the Jurassic Morrison Formation. Chemical and petrographic analyses were used to determine elemental variation and diagenetic aspects across the orebody. Vanadium is concentrated in the dark clay matrix, which constitutes visible ore. Uranium content is greater above the vanadium zone. Calcium, carbonate carbon, and lead show greater than fifty-fold increase across the ore zone, whereas copper and organic carbon show only a several-fold increase. Large molybdenum concentrations are present in and above the tabular layer, and large selenium concentrations occur below the uranium zone within the richest vanadium zone. Iron is enriched in the vanadium horizon. Chromium is depleted from above the ore and strongly enriched below. Elements that vary directly with the vanadium content include magnesium, iron, selenium, zirconium, strontium, titanium, lead, boron, yttrium, and scandium. The diagenetic sequence is as follows: (1) formation of secondary quartz overgrowths as cement; (2) infilling and lining of remaining pores with amber opaline material; (3) formation of vanadium-rich clay matrix, which has replaced overgrowths as well as quartz grains; (4) replacement of overgrowths and detrital grains by calcite; (5) infilling of pores with barite and the introduction of pyrite and marcasite.

Main principles of passive devices based on graphene and carbon films in microwave-THz frequency range

NASA Astrophysics Data System (ADS)

Kuzhir, Polina P.; Paddubskaya, Alesia G.; Volynets, Nadezhda I.; Batrakov, Konstantin G.; Kaplas, Tommi; Lamberti, Patrizia; Kotsilkova, Rumiana; Lambin, Philippe

2017-07-01

The ability of thin conductive films, including graphene, pyrolytic carbon (PyC), graphitic PyC (GrPyC), graphene with graphitic islands (GrI), glassy carbon (GC), and sandwich structures made of all these materials separated by polymer slabs to absorb electromagnetic radiation in microwave-THz frequency range, is discussed. The main physical principles making a basis for high absorption ability of these heterostructures are explained both in the language of electromagnetic theory and using representation of equivalent electrical circuits. The idea of using carbonaceous thin films as the main working elements of passive radiofrequency (RF) devices, such as shields, filters, polarizers, collimators, is proposed theoretically and proved experimentally. The important advantage of PyC, GrI, GrPyC, and GC is that, in contrast to graphene, they either can be easily deposited onto a dielectric substrate or are strong enough to allow their transfer from the catalytic substrate without a shuttle polymer layer. This opens a new avenue toward the development of a scalable protocol for cost-efficient production of ultralight electromagnetic shields that can be transferred to commercial applications. A robust design via finite-element method and design of experiment for RF devices based on carbon/graphene films and sandwiches is also discussed in the context of virtual prototyping.

Trace element analyses of fluid-bearing diamonds from Jwaneng, Botswana

NASA Astrophysics Data System (ADS)

Schrauder, Marcus; Koeberl, Christian; Navon, Oded

1996-12-01

Fibrous diamonds from Botswana contain abundant micro-inclusions, which represent syngenetic mantle fluids under high pressure. The major element composition of the fluids within individual diamonds was found to be uniform, but a significant compositional variation exists between different diamond specimens. The composition of the fluids varies between a carbonatitic and a hydrous endmember. To constrain the composition of fluids in the mantle, the trace element contents of thirteen micro-inclusion-bearing fibrous diamonds from Botswana was studied using neutron activation analysis. The concentrations of incompatible elements (including K, Na, Br, Rb, Sr, Zr, Cs, Ba, Hf, Ta, Th, U, and the LREEs) in the fluids are higher than those of mantle-derived rocks and melt inclusions. The compatible elements (e.g., Cr, Co, Ni) have abundances that are similar to those of the primitive mantle. The concentrations of most trace elements decrease by a factor of two from the carbonate-rich fluids to the hydrous fluids. Several models may explain the observed elemental variations. Minerals in equilibrium with the fluid were most likely enriched in incompatible elements, which does not agree with derivation of the fluids by partial melting of common peridotites or eclogites. Fractional crystallization of a kimberlite-like magma at depth may yield carbonatitic fluids with low mg numbers (atomic ratio [Mg/(Mg+Fe)]) and high trace element contents. Fractionation of carbonates and additional phases (e.g., rutile, apatite, zircon) may, in general, explain the concentrations of incompatible elements in the fluids, which preferably partition into these phases. Alternatively, mixing of fluids with compositions similar to those of the two endmembers may explain the observed variation of the elemental contents. The fluids in fibrous diamonds might have equilibrated with mineral inclusions in eclogitic diamonds, while peridotitic diamonds do not show evidence of interaction with these fluids. The chemical composition of the fluids in fibrous diamonds indicates that, at p, T conditions that are characteristic for diamond formation, carbonatitic and hydrous fluids are efficient carriers of incompatible elements.

No One's Home: the Fate of Carbon on Lifeless Earths

NASA Astrophysics Data System (ADS)

Neveu, Marc

Although several thousands of exoplanets are now known, including many terrestrial planets, their possible geology and climates remain poorly understood and understudied. Yet, understanding how elements such as carbon are cycled between a planet's interior, surface, and atmosphere is crucial to predict how lifeless planets operate and, by contrast, be able to detect deviations from abiotic backgrounds due to biology, the holy grail of exoplanet science. As a first, feasible step towards the difficult, long-term goal of understanding how key reactive elements (H, C, N, O, S) are cycled in the atmospheres, surfaces, and interiors of terrestrial exoplanets through time, we propose to carry out a self-consistent theoretical study of the fate of carbon in the atmospheres and at the surfaces of Earth-like, lifeless exoplanets. We will: 1. Model the near-surface geochemistry and geophysics of the carbon cycle to determine net carbon gas fluxes as a function of terrestrial planet size and redox conditions; 2. Model the atmospheric fate of carbon species as a function of stellar input; 3. Perform simulations that self-consistently combine geological and atmospheric processes; 4. Convert resulting atmospheric compositions to spectra to be archived as a public database for use by observers. We will track the abiotic fate of carbon and its atmospheric expression on Earth-like planets as a function of three key parameters: planet size, surface and atmospheric redox conditions, and stellar irradiation. To do so, we will further develop and use state-of-theart planetary geological ("Geo") and atmospheric ("Atmos") models. We have previously developed a code that couples geophysical evolution and water-rock geochemistry (Neveu et al. 2015, GRL 42, 10197). Using this code, we will calculate the speciation of carbon species versus depth in subaerial oceans, their possible incorporation into the crust by water-rock interaction at the seafloor or by subduction of sediments, and outgassing as a function of temperature, pressure, and fluid/rock composition. We will expand this code with benchmarked parameterizations of land and seafloor weathering and outgassing rates. This modeling will result in detailed boundary conditions to be implemented into an existing atmospheric photochemical-climate model (DomagalGoldman et al. 2014, ApJ 792, 90). The atmospheric model will be used to predict species mixing ratios from net surface fluxes, given planetary and stellar parameters. The models will be benchmarked against what is known of the surfaces and atmospheres of the Earth (present and prior to atmospheric oxygenation) and Titan. Atmospheric model outputs will be fed back into the geological model in combined simulations of carbon cycling. We will investigate in detail the mutual feedbacks between geological and atmospheric processes, so far understudied for terrestrial exoplanets. The resulting atmospheric compositions will be converted to predicted exoplanet spectra using the Spectral Mapping Atmospheric Radiative Transfer model (SMART; Meadows & Crisp 1996, JGR 101, 4595). This grid of spectra will be made freely available to the exoplanet community. This proposal is relevant to the Exoplanets Research Program (E.3) objectives, as it "supports directly the scientific goals of advancing our knowledge and understanding of exoplanetary systems." It involves the "characterization of exoplanets (including their surfaces, interiors, and atmospheres) [...] including the determination of their compositions, dynamics, energetics, and chemical behaviors." This investigation will also advance "understanding the chemical and physical processes of exoplanets (including the state and evolution of their surfaces, interiors, and atmospheres)." Furthermore, this proposal is not "aimed at investigating the habitability of an exoplanet" and therefore not relevant to the Habitable Worlds program element (E.4).

Mercury content of Illinois soils

USGS Publications Warehouse

Dreher, G.B.; Follmer, L.R.

2004-01-01

For a survey of Illinois soils, 101 cores had been collected and analyzed to determine the current and background elemental compositions of Illinois soils. Mercury and other elements were determined in six samples per core, including a surface sample from each core. The mean mercury content in the surface samples was 33 ?? 20 ??g/kg soil, and the background content was 20 ?? 9 ??g/kg. The most probable sources of mercury in these soils were the parent material, and wet and dry deposition of Hg0 and Hg2+ derived from coal-burning power plants, other industrial plants, and medical and municipal waste incinerators. Mercury-bearing sewage sludge or other fertilizers applied to agricultural fields could have been the local sources of mercury. Although the mercury content correlated with organic carbon content or clay content in individual cores, when all the data were considered, there was no strong correlation between mercury and either the organic carbon or the clay-size content.

Comparing the NIOSH Method 5040 to a Diesel Particulate Matter Meter for Elemental Carbon

NASA Astrophysics Data System (ADS)

Ayers, David Matthew

Introduction: The sampling of elemental carbon has been associated with monitoring exposures in the trucking and mining industries. Recently, in the field of engineered nanomaterials, single wall and muti-wall carbon nanotubes (MWCNTs) are being produced in ever increasing quantities. The only approved atmospheric sampling for multi-wall carbon nanotubes in NIOSH Method 5040. These results are accurate but can take up to 30 days for sample results to be received. Objectives: Compare the results of elemental carbon sampling from the NIOSH Method 5040 to a Diesel Particulate Matter (DPM) Meter. Methods: MWCNTs were transferred and weighed between several trays placed on a scale. The NIOSH Method 5040 and DPM sampling train was hung 6 inches above the receiving tray. The transferring and weighing of the MWCNTs created an aerosol containing elemental carbon. Twenty-one total samples using both meters type were collected. Results: The assumptions for a Two-Way ANOVA were violated therefore, Mann-Whitney U Tests and a Kruskal-Wallis Test were performed. The hypotheses for both research questions were rejected. There was a significant difference in the EC concentrations obtained by the NIOSH Method 5040 and the DPM meter. There were also significant differences in elemental carbon level concentrations when sampled using a DPM meter versus a sampling pump based upon the three concentration levels (low, medium and high). Conclusions: The differences in the EC concentrations were statistically significant therefore, the two methods (NIOSH Method 5040 and DPM) are not the same. The NIOSH Method 5040 should continue to be the only authorized method of establishing an EC concentration for MWCNTs until a MWCNT specific method or an instantaneous meter is invented.

Intrinsic activation: the relationship between biomass inorganic content and porosity formation during pyrolysis.

PubMed

Stratford, James P; Hutchings, Tony R; de Leij, Frans A A M

2014-05-01

The utility of pyrolytic carbons is closely related to their porosity and surface area, there is a clear benefit to the development of biomass pyrolysis processes which produce highly porous carbons. The results presented in this work demonstrate that by using biomass precursors with high inorganic content along with specified process conditions, carbons can be consistently produced with specific surface areas between 900 and 1600 m(2)/g. Results from 12 different source materials show that the formation of increased porosity in pyrolytic carbons is strongly associated with the presence of inorganic elements in the precursors including: magnesium, potassium and sulfur. It was found that pyrolysis of macro-algae can produce especially high specific surface area carbons (mean: 1500 m(2)/g), without externally applied activating agents. Using cheap readily available agricultural residues such as oilseed rape straw, pyrolytic carbons can be produced with specific surface areas of around 950 m(2)/g. Copyright © 2014 Elsevier Ltd. All rights reserved.

Chemical composition and origin of black patinas on granite.

PubMed

Silva, Benita; Aira, Noelia; Martínez-Cortizas, Antonio; Prieto, Beatriz

2009-12-15

Black patinas from the surfaces of granite outcrops (including some with engravings) and granite buildings were analysed. Rock samples were also taken from areas of the same surfaces where there were no black patinas. The constituent elements of the granite rocks, elements of essentially biological origin (C, N, H) and other minor elements, including some typical from pollution, were all determined. The ratios between the concentrations of each element in the patinas and in the corresponding rock samples without patina were calculated in order to determine which elements form the patinas. The data were then examined by hierarchical cluster analysis and principal components analysis to establish the factors that determine the differences between samples. It was found that the elements that differentiate the patinas from the samples of rock without patina are those unrelated to granite, which indicates that, at least from a geochemical point of view, the rocky substrate does not affect patina formation. In all patinas analysed, the concentrations of carbon were higher than in the corresponding samples without patina; there were also relatively higher concentrations of sulphur, phosphorus, chlorine, calcium, etc. in some patinas, depending on the situation of the outcrop or monument.

An efficient copper-based magnetic nanocatalyst for the fixation of carbon dioxide at atmospheric pressure.

PubMed

Sharma, Rakesh Kumar; Gaur, Rashmi; Yadav, Manavi; Goswami, Anandarup; Zbořil, Radek; Gawande, Manoj B

2018-01-30

In the last few decades, the emission of carbon dioxide (CO 2 ) in the environment has caused havoc across the globe. One of the most promising strategies for fixation of CO 2 is the cycloaddition reaction between epoxides and CO 2 to produce cyclic carbonates. For the first time, we have fabricated copper-based magnetic nanocatalyst and have applied for the CO 2 fixation. The prepared catalyst was thoroughly characterized using various techniques including XRD, FT-IR, TEM, FE-SEM, XPS, VSM, ICP-OES and elemental mapping. The reactions proceeded at atmospheric pressure, relatively lower temperature, short reaction time, solvent- less and organic halide free reaction conditions. Additionally, the ease of recovery through an external magnet, reusability of the catalyst and excellent yields of the obtained cyclic carbonates make the present protocol practical and sustainable.

Lightning Damage of Carbon Fiber/Epoxy Laminates with Interlayers Modified by Nickel-Coated Multi-Walled Carbon Nanotubes

NASA Astrophysics Data System (ADS)

Dong, Qi; Wan, Guoshun; Xu, Yongzheng; Guo, Yunli; Du, Tianxiang; Yi, Xiaosu; Jia, Yuxi

2017-12-01

The numerical model of carbon fiber reinforced polymer (CFRP) laminates with electrically modified interlayers subjected to lightning strike is constructed through finite element simulation, in which both intra-laminar and inter-laminar lightning damages are considered by means of coupled electrical-thermal-pyrolytic analysis method. Then the lightning damage extents including the damage volume and maximum damage depth are investigated. The results reveal that the simulated lightning damages could be qualitatively compared to the experimental counterparts of CFRP laminates with interlayers modified by nickel-coated multi-walled carbon nanotubes (Ni-MWCNTs). With higher electrical conductivity of modified interlayer and more amount of modified interlayers, both damage volume and maximum damage depth are reduced. This work provides an effective guidance to the anti-lightning optimization of CFRP laminates.

Black carbon, mass and elemental measurements of airborne particles in the village of Serowe, Botswana

NASA Astrophysics Data System (ADS)

Moloi, K.; Chimidza, S.; Lindgren, E. Selin; Viksna, A.; Standzenieks, P.

Absorption of sunlight by sub-micron particles is an important factor in calculations of the radiation balance of the earth and thus in climate modelling. Carbon-containing particles are generally considered as the most important in this respect. Major sources of these particles are generally considered to be bio-mass burning and vehicle exhaust. In order to characterise size fractionated particulate matter in a rural village in Botswana with respect to light absorption and elemental content experiments were performed, in which simultaneous sampling was made with a dichotomous impactor and a laboratory-made sampler, made compatible with black carbon analysis by reflectometry. The dichotomous impactor was equipped with Teflon filters and the other sampler with glass fibre filters. Energy dispersive X-ray fluorescence was used for elemental analysis of both kinds of filters. It appeared that Teflon filters were the most suitable for the combination of mass-, elemental- and black carbon measurements. The black carbon content in coarse (2.5-10 μm) and fine (<2.5 μm) particles was determined separately and related to elemental content and emission source. The results show that the fine particle fraction in the aerosol has a much higher contribution of black particles than the coarse particle fraction. This observation is valid for the village in Botswana as well as for a typical industrialised city in Sweden, used as a reference location.

Exposure of miners to diesel exhaust particulates in underground nonmetal mines.

PubMed

Cohen, H J; Borak, J; Hall, T; Sirianni, G; Chemerynski, S

2002-01-01

A study was initiated to examine worker exposures in seven underground nonmetal mines and to examine the precision of the National Institute for Occupational Safety and Health (NIOSH) 5040 sampling and analytical method for diesel exhaust that has recently been adopted for compliance monitoring by the Mine Safety and Health Administration (MSHA). Approximately 1000 air samples using cyclones were taken on workers and in areas throughout the mines. Results indicated that worker exposures were consistently above the MSHA final limit of 160 micrograms/m3 (time-weighted average; TWA) for total carbon as determined by the NIOSH 5040 method and greater than the proposed American Conference of Governmental Industrial Hygienists TLV limit of 20 micrograms/m3 (TWA) for elemental carbon. A number of difficulties were documented when sampling for diesel exhaust using organic carbon: high and variable blank values from filters, a high variability (+/- 20%) from duplicate punches from the same sampling filter, a consistent positive interference (+26%) when open-faced monitors were sampled side-by-side with cyclones, poor correlation (r 2 = 0.38) to elemental carbon levels, and an interference from limestone that could not be adequately corrected by acid-washing of filters. The sampling and analytical precision (relative standard deviation) was approximately 11% for elemental carbon, 17% for organic carbon, and 11% for total carbon. An hypothesis is presented and supported with data that gaseous organic carbon constituents of diesel exhaust adsorb onto not only the submicron elemental carbon particles found in diesel exhaust, but also mining ore dusts. Such mining dusts are mostly nonrespirable and should not be considered equivalent to submicron diesel particulates in their potential for adverse pulmonary effects. It is recommended that size-selective sampling be employed, rather than open-faced monitoring, when using the NIOSH 5040 method.

Abundances in 54 Chemical Elements in Przybylski's Star: HD 101065

NASA Astrophysics Data System (ADS)

Cowley, Charles R.; et al.

We report abundances from carbon through uranium, based on ESO observations: SN >= 200, resolution 80,000. Light elements, through the iron group scatter with respect to the standard abundance distribution (SAD). Carbon and oxygen are mildly depleted, as are iron and nickel, while titanium and cobalt are enhanced. Calcium is depleted, but silicon, sulfur, and scandium are solar. The heavier elements including some 4d and REE's are generally enhanced by 3 to 4 dex. This is not extreme for an Ap star. The truly bizarre appearance of the spectrum is an an ionization phenomena. Some hotter Ap stars have comparable lanthanide abundances, but their second spectra are weaker due to double ionization. Our adopted model has a Te of 6600K, and log(g) = 4.2. Because of the high line opacity, the photospheric pressure is low, and convection is ineffective. Chemical separation has distorted the third r-process peak only slightly. The overall coherence of the heavier elements is remarkable. Additional information is available from http://www.astro.lsa.umich.edu/users/cowley/przyb.html. This abstract is based on a paper submitted to MNRAS, by CRC, and coauthors: T. A. Ryabchikova (Moscow & Vienna), F. Kupka (Vienna), D. Bord (Michigan), G. Mathys (ESO), and W. P. Bidelman (Case-Western Reserve).

Process recognition in multi-element soil and stream-sediment geochemical data

USGS Publications Warehouse

Grunsky, E.C.; Drew, L.J.; Sutphin, D.M.

2009-01-01

Stream-sediment and soil geochemical data from the Upper and Lower Coastal Plains of South Carolina (USA) were studied to determine relationships between soils and stream sediments. From multi-element associations, characteristic compositions were determined for both media. Primary associations of elements reflect mineralogy, including heavy minerals, carbonates and clays, and the effects of groundwater. The effects of groundwater on element concentrations are more evident in soils than stream sediments. A "winnowing index" was created using ratios of Th to Al that revealed differing erosional and depositional environments. Both soils and stream sediments from the Upper and Lower Coastal Plains show derivation from similar materials and subsequent similar multi-element relationships, but have some distinct differences. In the Lower Coastal Plain, soils have high values of elements concentrated in heavy minerals (Ce, Y, Th) that grade into high values of elements concentrated into finer-grain-size, lower-density materials, primarily comprised of carbonates and feldspar minerals (Mg, Ca, Na, K, Al). These gradational trends in mineralogy and geochemistry are inferred to reflect reworking of materials during marine transgressions and regressions. Upper Coastal Plain stream-sediment geochemistry shows a higher winnowing index relative to soil geochemistry. A comparison of the 4 media (Upper Coastal Plain soils and stream sediments and Lower Coastal Plain soils and stream sediments) shows that Upper Coastal Plain stream sediments have a higher winnowing index and a higher concentration of elements contained within heavy minerals, whereas Lower Coastal Plain stream sediments show a strong correlation between elements typically contained within clays. It is not possible to calculate a functional relationship between stream sediment-soil compositions for all elements due to the complex history of weathering, deposition, reworking and re-deposition. However, depending on the spatial separation of the stream-sediment and soil samples, some elements are more highly correlated than others. Crown Copyright ?? 2009.

MODELING REFLECTANCE AND TRANSMITTANCE OF QUARTZ-FIBER FILTER SAMPLES CONTAINING ELEMENTAL CARBON PARTICLES: IMPLICATIONS FOR THERMAL/OPTICAL ANALYSIS. (R831086)

EPA Science Inventory

A radiative transfer scheme that considers absorption, scattering, and distribution of light-absorbing elemental carbon (EC) particles collected on a quartz-fiber filter was developed to explain simultaneous filter reflectance and transmittance observations prior to and during...

Quantitative evaluation of potential irradiation geometries for carbon-ion beam grid therapy.

PubMed

Tsubouchi, Toshiro; Henry, Thomas; Ureba, Ana; Valdman, Alexander; Bassler, Niels; Siegbahn, Albert

2018-03-01

Radiotherapy using grids containing cm-wide beam elements has been carried out sporadically for more than a century. During the past two decades, preclinical research on radiotherapy with grids containing small beam elements, 25 μm-0.7 mm wide, has been performed. Grid therapy with larger beam elements is technically easier to implement, but the normal tissue tolerance to the treatment is decreasing. In this work, a new approach in grid therapy, based on irradiations with grids containing narrow carbon-ion beam elements was evaluated dosimetrically. The aim formulated for the suggested treatment was to obtain a uniform target dose combined with well-defined grids in the irradiated normal tissue. The gain, obtained by crossfiring the carbon-ion beam grids over a simulated target volume, was quantitatively evaluated. The dose distributions produced by narrow rectangular carbon-ion beams in a water phantom were simulated with the PHITS Monte Carlo code. The beam-element height was set to 2.0 cm in the simulations, while the widths varied from 0.5 to 10.0 mm. A spread-out Bragg peak (SOBP) was then created for each beam element in the grid, to cover the target volume with dose in the depth direction. The dose distributions produced by the beam-grid irradiations were thereafter constructed by adding the dose profiles simulated for single beam elements. The variation of the valley-to-peak dose ratio (VPDR) with depth in water was thereafter evaluated. The separation of the beam elements inside the grids were determined for different irradiation geometries with a selection criterion. The simulated carbon-ion beams remained narrow down to the depths of the Bragg peaks. With the formulated selection criterion, a beam-element separation which was close to the beam-element width was found optimal for grids containing 3.0-mm-wide beam elements, while a separation which was considerably larger than the beam-element width was found advantageous for grids containing 0.5-mm-wide beam elements. With the single-grid irradiation setup, the VPDRs were close to 1.0 already at a distance of several cm from the target. The valley doses given to the normal tissue at 0.5 cm distance from the target volume could be limited to less than 10% of the mean target dose if a crossfiring setup with four interlaced grids was used. The dose distributions produced by grids containing 0.5- and 3.0-mm wide beam elements had characteristics which could be useful for grid therapy. Grids containing mm-wide carbon-ion beam elements could be advantageous due to the technical ease with which these beams can be produced and delivered, despite the reduced threshold doses observed for early and late responding normal tissue for beams of millimeter width, compared to submillimetric beams. The treatment simulations showed that nearly homogeneous dose distributions could be created inside the target volumes, combined with low valley doses in the normal tissue located close to the target volume, if the carbon-ion beam grids were crossfired in an interlaced manner with optimally selected beam-element separations. The formulated selection criterion was found useful for the quantitative evaluation of the dose distributions produced by the different irradiation setups. © 2018 The Authors. Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine.

A Carbon Source Apportionment Shift in Mexico City Atmospheric Particles During 2003-2004 as Determined with Stable Carbon Isotopes

NASA Astrophysics Data System (ADS)

Lopez-Veneroni, D. G.; Vega, E.

2013-05-01

The stable carbon isotope composition of atmospheric particles (PM2.5) was measured at La Merced (MER), a commercial site in the eastern sector, and at Xalostoc (XAL) an industrial site in the NE sector of Mexico City, during three sampling periods in autumn 2003, and spring and autumn 2004. At each site and sampling campaign particle samples were collected daily with minivol samplers during two week periods. Ancillary data included organic and elemental carbon, trace elements and ionic species. This data base was complement with air quality data from the RAMA (Automatic Atmospheric Monitoring Network). In general, particle concentrations, ionic species and some air quality species showed higher concentrations in autumn and lowest values in spring. Moreover, the concentrations of these chemical species were highest at XAL compared to MER. The stable carbon isotope composition of PM2.5 during autumn 2003 and spring 2004 had and average value of -26.04 (± 1.54) ‰ vs. PDB. Differences in the isotopic composition between the two sites were non significant. The average δ13C during these seasons were 1 ‰ lighter relative to data collected previously at these sites during 2000 and 2001, and is consistent with a predominant source of hydrocarbon combustion. In autumn 2004, however, average δ13C at XAL and MER increased to -22.8 (± 0.9) and -20.6 (± 3.1) ‰, respectively. Organic carbon concentrations during this period increased concomitantly at these sites. The shift in the isotopic composition in ambient particles suggests a predominance of soil-derived carbon during this period. The possible causes and implications of this are discussed.

Acid pre-treatment method for in situ ore leaching

DOEpatents

Mallon, R.G.; Braun, R.L.

1975-10-28

An acid leaching method is described for the recovery of a desired element from a subterranean rubblized body of primary ore containing the element and also having associated therewith a carbonate mineral wherein the rubblized ore body is flooded with an aqueous acidic solution in order to release carbon dioxide from the associated carbonate mineral. After a substantial portion of the available carbon dioxide is released and removed from the ore body, as by venting to the atmosphere, an oxidizing gas is introduced into the flooded, rubblized ore to oxidize the ore and form an acid leach solution effective in the presence of the dissolved oxidizing gas to dissolve the ore and cause the desired element to go into solution. The leach solution is then circulated to the surface where the metal values are recovered therefrom.

Biogeochemistry of carbon and related major and trace elements in peat bog soils of the middle taiga of Western Siberia (Russia).

NASA Astrophysics Data System (ADS)

Stepanova, V. A.; Mironycheva-Tokareva, N. P.; Pokrovsky, O. S.

2012-04-01

Global climate changes impact the status of wetland ecosystems shifting the balances of the carbon, macro-, and microelements cycles. This study aims to establish the features of accumulation and distribution of major- and trace elements in the organic layer of peat bog soils, belonging to different ecosystems of the oligotrophic bog complex located in the middle taiga of Western Siberia (Khanty-Mansiysk region, Russia). Key areas which are selected for this study include the following bog conjugate elementary ecosystems: higher ryam, lower ryam, ridge-hollow complex, and oligotrophic poor fen as characterized previously [1]. We have sampled various peat types along the entire length of the soil column (every 10 cm down to 3 m). Peat samples were analyzed for a wide range of macro- and microelements using an ICP-MS technique following full acid digestion in a microwave oven. These measurements allowed quantitative estimates of major- and trace elements in the peat deposits within the whole bog complex and individual elementary landscapes. Based on the data obtained, the lateral and radial geochemical structures of the bog landscapes were determined and clarified for the first time for middle taiga of the West Siberian plain. The similar regime of mineral nutrition during the complete bog landscape formation was detected for the peat deposits based on the measurements of some major- and trace elements (Ca, Fe, Mg, etc.). The vertical distribution of some major and some trace elements along the profile of peat column is rather uniform with relatively strong increase in the bottom organic layers. This strongly suggests the similarity of the processes of element accumulation in the peat and relatively weak post depositional redistribution of elements within the peat soil profile. Overall, obtained corroborate the existing view on chemical composition of peats being determined by botanical peat's components (which forms this peat deposit), atmospheric precipitation, position of ecosystems in the landscape (lateral migration) and types of bedrocks [2]. The results allow better understanding of the coupling between biogeochemical cycles of carbon and major and trace elements in peat soils in order to predict the future changes in both concentrations and stocks of chemical elements in the Western Siberia peat bog systems under climate warming.

Soil data from Picea mariana stands near delta junction, Alaska of different ages and soil drainage type

USGS Publications Warehouse

Manies, Kristen L.; Harden, Jennifer W.; Silva, Steven R.; Briggs, Paul H.; Schmid, Brian M.

2004-01-01

The U.S. Geological Survey project Fate of Carbon in Alaskan Landscapes (FOCAL) is studying the effect of fire and soil drainage on soil carbon storage in the boreal forest. This project has selected several sites to study within central Alaska of varying ages (time since fire) and soil drainage types. This report describes the location of these sampling sites, as well as the procedures used to describe, sample, and analyze the soils. This report also contains data tables with this information, including, but not limited to field descriptions, bulk density, particle size distribution, moisture content, carbon (C) concentration, nitrogen (N) concentration, isotopic data for C, and major, minor and trace elemental concentration.

Carbon and sulfur budget of the silicate Earth explained by accretion of differentiated planetary embryos

NASA Astrophysics Data System (ADS)

Li, Yuan; Dasgupta, Rajdeep; Tsuno, Kyusei; Monteleone, Brian; Shimizu, Nobumichi

2016-10-01

The abundances of volatile elements in the Earth's mantle have been attributed to the delivery of volatile-rich material after the main phase of accretion. However, no known meteorites could deliver the volatile elements, such as carbon, nitrogen, hydrogen and sulfur, at the relative abundances observed for the silicate Earth. Alternatively, Earth could have acquired its volatile inventory during accretion and differentiation, but the fate of volatile elements during core formation is known only for a limited set of conditions. Here we present constraints from laboratory experiments on the partitioning of carbon and sulfur between metallic cores and silicate mantles under conditions relevant for rocky planetary bodies. We find that carbon remains more siderophile than sulfur over a range of oxygen fugacities; however, our experiments suggest that in reduced or sulfur-rich bodies, carbon is expelled from the segregating core. Combined with previous constraints, we propose that the ratio of carbon to sulfur in the silicate Earth could have been established by differentiation of a planetary embryo that was then accreted to the proto-Earth. We suggest that the accretion of a Mercury-like (reduced) or a sulfur-rich (oxidized) differentiated body--in which carbon has been preferentially partitioned into the mantle--may explain the Earth's carbon and sulfur budgets.

PROCESS FOR PRODUCTION OF URANIUM HEXAFLUORIDE

DOEpatents

Fowler, R.D.

1958-11-01

A process is described for the manufacture of uranium bexafluoride which consists in contacting an oxide of uranium simultaneously with elemental carbon and elemental fluorine at an elevated temperature, using a proportion of the carbon to the oxide about 50% in excess of that theoretically required to combine with f the oxygen as C0/.sub 2/. The process has the advantage that the uranium oxide is reduced by tbe carbon aad converted to the hexafluoride in a single operation.

Sputtered carbon as a corrosion barrier for x-ray detector windows

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

Rowley, Joseph; Pei, Lei; Davis, Robert C., E-mail: davis@byu.edu

Sputtered amorphous carbon thin films were explored as corrosion resistant coatings on aluminum thin films to be incorporated into x-ray detector windows. The requirements for this application include high corrosion resistance, low intrinsic stress, high strains at failure, and high x-ray transmission. Low temperature sputtering was used because of its compatibility with the rest of the window fabrication process. Corrosion resistance was tested by exposure of carbon coated and uncoated Al thin films to humidity. Substrate curvature and bulge testing measurements were used to determine intrinsic stress and ultimate strain at failure. The composition and bonding of the carbon filmsmore » were further characterized by electron energy loss spectroscopy, Raman spectroscopy, and carbon, hydrogen, and nitrogen elemental analyses. Samples had low compressive stress (down to.08 GPa), a high strain at failure (3%), and a low fraction of sp{sup 3} carbon–carbon bonds (less than 5%). The high breaking strain and excellent x-ray transmission of these sputtered carbon films indicate that they will work well as corrosion barriers in this application.« less

Laboratory simulation of meteoritic noble gases. III - Sorption of neon, argon, krypton, and xenon on carbon - Elemental fractionation

NASA Technical Reports Server (NTRS)

Wacker, John F.

1989-01-01

The sorption of Ne, Ar, Kr, and Xe was studied in carbon black, acridine carbon, and diamond in an attempt to understand the origin of trapped noble gases in meteorites. The results support a model in which gases are physically adsorbed on interior surfaces formed by a pore labyrinth within amorphous carbons. The data show that: (1) the adsorption/desorption times are controlled by choke points that restrict the movement of noble gas atoms within the pore labyrinth, and (2) the physical adsorption controls the temperature behavior and elemental fractionation patterns.

Comprehensive model for predicting elemental composition of coal pyrolysis products

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

Ricahrds, Andrew P.; Shutt, Tim; Fletcher, Thomas H.

Large-scale coal combustion simulations depend highly on the accuracy and utility of the physical submodels used to describe the various physical behaviors of the system. Coal combustion simulations depend on the particle physics to predict product compositions, temperatures, energy outputs, and other useful information. The focus of this paper is to improve the accuracy of devolatilization submodels, to be used in conjunction with other particle physics models. Many large simulations today rely on inaccurate assumptions about particle compositions, including that the volatiles that are released during pyrolysis are of the same elemental composition as the char particle. Another common assumptionmore » is that the char particle can be approximated by pure carbon. These assumptions will lead to inaccuracies in the overall simulation. There are many factors that influence pyrolysis product composition, including parent coal composition, pyrolysis conditions (including particle temperature history and heating rate), and others. All of these factors are incorporated into the correlations to predict the elemental composition of the major pyrolysis products, including coal tar, char, and light gases.« less

Cost analysis of carbon dioxide concentrators

NASA Technical Reports Server (NTRS)

Yakut, M. M.

1972-01-01

A methodology is developed to predict the relevant contributions of the more intangible cost elements encountered in the development of flight-qualified hardware and is used to predict the costs of three carbon dioxide concentration systems. The cost and performance data from Gemini, Skylab, and other programs are utilized as a basis for establishing the cost estimating relationships. The concentration systems analyzed are the molecular sieves C02 concentrator, the hydrogen-depolarized concentrator, and the regenerable solid desiccant concentrator. Besides the cost estimates for each system, their comparative criteria including relative characteristics, operational differences, and development status are considered.

Multilayer Electroactive Polymer Composite Material Comprising Carbon Nanotubes

NASA Technical Reports Server (NTRS)

Ounaies, Zoubeida (Inventor); Park, Cheol (Inventor); Harrison, Joycelyn S. (Inventor); Holloway, Nancy M. (Inventor); Draughon, Gregory K. (Inventor)

2009-01-01

An electroactive material comprises multiple layers of electroactive composite with each layer having unique dielectric, electrical and mechanical properties that define an electromechanical operation thereof when affected by an external stimulus. For example, each layer can be (i) a 2-phase composite made from a polymer with polarizable moieties and an effective amount of carbon nanotubes incorporated in the polymer for a predetermined electromechanical operation, or (ii) a 3-phase composite having the elements of the 2-phase composite and further including a third component of micro-sized to nano-sized particles of an electroactive ceramic incorporated in the polymer matrix.

Determining Inorganic and Organic Carbon.

PubMed

Koistinen, Jaana; Sjöblom, Mervi; Spilling, Kristian

2017-11-21

Carbon is the element which makes up the major fraction of lipids and carbohydrates, which could be used for making biofuel. It is therefore important to provide enough carbon and also follow the flow into particulate organic carbon and potential loss to dissolved organic forms of carbon. Here we present methods for determining dissolved inorganic carbon, dissolved organic carbon, and particulate organic carbon.

Comparison of the morphology, chemical composition and microstructure of cryptocrystalline graphite and carbon black

NASA Astrophysics Data System (ADS)

Quan, Ying; Liu, Qinfu; Zhang, Shilong; Zhang, Shuai

2018-07-01

The structures of cryptocrystalline graphite (CG) and carbon black (CB) have been analyzed using scanning electron microscopy (SEM), transmission electron microscopy (TEM), organic elemental analysis (OEA), X-ray diffraction (XRD), RAMAN and high-resolution transmission electron microscopy (HRTEM). These results indicate that CG has the same elemental composition as CB, with carbon being the major element present. SL sample (CG with low graphitization degree) and CB exhibit similar microcrystalline structures. CG was shown to contain a layered graphitic structure that was significantly different to the primary spherical particles present in CB. It is proposed that these CG sheets may potentially be reduced and delaminated to afford multilayer graphene structures with improved material properties.

Chemical characterization of fine particulate matter in Changzhou, China, and source apportionment with offline aerosol mass spectrometry

NASA Astrophysics Data System (ADS)

Ye, Zhaolian; Liu, Jiashu; Gu, Aijun; Feng, Feifei; Liu, Yuhai; Bi, Chenglu; Xu, Jianzhong; Li, Ling; Chen, Hui; Chen, Yanfang; Dai, Liang; Zhou, Quanfa; Ge, Xinlei

2017-02-01

Knowledge of aerosol chemistry in densely populated regions is critical for effective reduction of air pollution, while such studies have not been conducted in Changzhou, an important manufacturing base and populated city in the Yangtze River Delta (YRD), China. This work, for the first time, performed a thorough chemical characterization on the fine particulate matter (PM2.5) samples, collected during July 2015 to April 2016 across four seasons in this city. A suite of analytical techniques was employed to measure the organic carbon (OC), elemental carbon (EC), water-soluble organic carbon (WSOC), water-soluble inorganic ions (WSIIs), trace elements, and polycyclic aromatic hydrocarbons (PAHs) in PM2.5; in particular, an Aerodyne soot particle aerosol mass spectrometer (SP-AMS) was deployed to probe the chemical properties of water-soluble organic aerosol (WSOA). The average PM2.5 concentration was found to be 108.3 µg m-3, and all identified species were able to reconstruct ˜ 80 % of the PM2.5 mass. The WSIIs occupied about half of the PM2.5 mass (˜ 52.1 %), with SO42-, NO3-, and NH4+ as the major ions. On average, nitrate concentrations dominated over sulfate (mass ratio of 1.21), indicating that traffic emissions were more important than stationary sources. OC and EC correlated well with each other and the highest OC / EC ratio (5.16) occurred in winter, suggesting complex OC sources likely including both secondary and primary ones. Concentrations of eight trace elements (Mn, Zn, Al, B, Cr, Cu, Fe, Pb) can contribute up to ˜ 5.0 % of PM2.5 during winter. PAH concentrations were also high in winter (140.25 ng m-3), which were predominated by median/high molecular weight PAHs with five and six rings. The organic matter including both water-soluble and water-insoluble species occupied ˜ 21.5 % of the PM2.5 mass. SP-AMS determined that the WSOA had average atomic oxygen-to-carbon (O / C), hydrogen-to-carbon (H / C), nitrogen-to-carbon (N / C), and organic matter-to-organic carbon (OM / OC) ratios of 0.54, 1.69, 0.11, and 1.99, respectively. Source apportionment of WSOA further identified two secondary OA (SOA) factors (a less oxidized and a more oxidized oxygenated OA) and two primary OA (POA) factors (a nitrogen-enriched hydrocarbon-like traffic OA and a local primary OA likely including species from cooking, coal combustion, etc.). On average, the POA contribution outweighed SOA (55 % vs. 45 %), indicating the important role of local anthropogenic emissions in the aerosol pollution in Changzhou. Our measurement also shows the abundance of organic nitrogen species in WSOA, and the source analyses suggest these species are likely associated with traffic emissions, which warrants more investigations on PM samples from other locations.

Sensitivity of Inverse Estimation of 2004 Elemental Carbon Emissions Inventory in the United States to the Choice of Observational Networks

EPA Science Inventory

Choice of observational networks used for inverse re-estimation of elemental (or black) carbon (EC) emissions in the United States impacts results. We convert the Thermal Optical Transmittance (TOT) EC measurements to the Thermal Optical Reflectance (TOR) equivalent to make full...

Calculation of the bending of electromechanical aircraft element made of the carbon fiber

NASA Astrophysics Data System (ADS)

Danilova-Volkovskaya, Galina; Chepurnenko, Anton; Begak, Aleksandr; Savchenko, Andrey

2017-10-01

We consider a method of calculation of an orthotropic plate with variable thickness. The solution is performed numerically by the finite element method. The calculation is made for the springs of a hang glider made of carbon fiber. The comparison of the results with Sofistik software complex is given.

Quantitative assessment of elemental carbon in the lungs of never smokers, cigarette smokers and coal miners

EPA Science Inventory

Inhalation exposure to particulates such as cigarette smoke and coal dust is known to contribute to the development of chronic lung disease. The purpose of this study was to estimate the amount of elemental carbon (EC) deposits from autopsied lung samples from cigarette smokers, ...

Geochemistry of the Nsuta Mn deposit in Ghana: Implications for the Paleoproterozoic atmosphere and ocean chemistry

NASA Astrophysics Data System (ADS)

Goto, K. T.; Ito, T.; Suzuki, K.; Kashiwabara, T.; Takaya, Y.; Shimoda, G.; Nozaki, T.; Kiyokawa, S.; Tetteh, G. M.; Nyame, F. K.

2013-12-01

Oxygenation of the atmosphere and oceans has influenced the evolution of ocean chemistry and diversification of early life. A number of large manganese (Mn) deposits are distributed in the Paleoproterozoic sedimentary successions that were formed during the great oxidation event (GOE) around 2.4-2.2 Ga (Meynard, 2010). Due to the high redox potential of Mn, occurrences of Mn deposits have been regarded as important evidence for a highly oxidized environment during the Paleoproterozoic (Kirschvink et al., 2000). Furthermore, because Mn oxides strongly adsorb various elements, including bioessential elements such as Mo, formation of large Mn deposits may have affected the seawater chemical composition and ecology during the Paleoproterozoic. However, the genesis of each Mn deposit is poorly constrained, and the relationships among the formation of Mn deposits, the evolution of atmospheric and ocean chemistry, and the diversification of early life are still ambiguous. In this study, we report the Re-Os isotope compositions, rare earth element (REE) compositions, and abundance of manganophile elements in the Mn carbonate ore and host sedimentary rock samples collected from the Nsuta Mn deposit of the Birimian Supergroup, Ghana. The Nsuta deposit is one of the largest Paleoproterozoic Mn deposits, although its genesis remains controversial (Melcher et al., 1995; Mucke et al., 1999). The composite Re-Os isochron age (2149 × 130 Ma) of the Mn carbonate and sedimentary rock samples was consistent with the depositional age of the sedimentary rocks (~2.2 Ga) presumed from the U-Pb zircon age of volcanic rocks (Hirdes and Davis, 1998), suggesting that the timing of Mn ore deposition was almost equivalent to the host rock sedimentation. The PAAS-normalized REE pattern showed a positive Eu anomaly in all samples and a positive Ce anomaly only in the Mn carbonate ore. These REE patterns indicate the possible contribution of Eu-enriched fluids derived from hydrothermal activity and Ce enrichment due to the oxidation of Ce(III) by Mn(IV) during an ore formation. Among the manganophile elements, merely Mo is enriched in the Mn carbonate ore compared with the host sedimentary rocks. The profile of manganophile elements was similar to that of modern hydrothermal Mn oxide (Kuhn et al., 2003), although the exact Mo concentration was much lower. These geochemical lines of evidence provide the following plausible genetic model for the Nsuta deposits: (1) Mn(II) was derived from hydrothermal vents, (2) Mn(II) was oxidized to Mn(IV) oxide by the oxygenated seawater, (3) the precipitation of Mn oxide is almost concurrent with the deposition of the host sedimentary rocks, (4) Mn oxide was diagenetically transformed to be a Mn carbonate ore. The geochemical features of the Nsuta deposits suggest that, as in the present oxic oceans, Mn oxide was a potential sink for several trace elements in the Paleoproterozoic oceans. The low-Mo concentration in the Mn carbonate ore probably reflects the large difference between the chemical compositions of Paleoproterozoic and present seawater, implying the prevalence of reduced marine conditions even during the GOE (Scott et al., 2008)

High-resolution (30 m), annual (1986 - 2010) carbon stocks and fluxes for southeastern US forests derived from remote sensing, inventory data, and a carbon cycle model

NASA Astrophysics Data System (ADS)

Gu, H.; Zhou, Y.; Williams, C. A.

2016-12-01

Disturbance events are highly heterogeneous in space and time, impacting forest carbon dynamics and challenging the quantification and reporting of carbon stocks and flux. This study documents annual carbon stocks and fluxes from 1986 and 2010 mapped at 30-m resolution across southeastern US forests, characterizing how they respond to disturbances and ensuing regrowth. Forest inventory data (FIA) are used to parameterize a carbon cycle model (CASA) to represent post-disturbance carbon trajectories of carbon pools and fluxes for harvest, fire and bark beetle disturbances of varying severity and across forest types and site productivity settings. Time since disturbance at 30 meters is inferred from two remote-sensing data sources: disturbance year (NAFD, MTBS and ADS) and biomass (NBCD 2000) intersected with inventory-derived curves of biomass accumulation with stand age. All of these elements are combined to map carbon stocks and fluxes at a 30-m resolution for the year 2010, and to march backward in time for continuous, annual reporting. Results include maps of annual carbon stocks and fluxes for forests of the southeastern US, and analysis of spatio-temporal patterns of carbon sources/sinks at local and regional scales.

Chemical Characteristics of Seawater and Sediment in the Yap Trench

NASA Astrophysics Data System (ADS)

Ding, H.; Sun, C.; Yang, G.

2017-12-01

In June 2016, seawater samples at sediment-seawater interface and sediment samples were collected by the he Jiaolong, China's manned submersible, at four sampling sites located in the Yap Trench. Seawater samples from different depths of the trench were also collected by CTD. Chemical parameters, including pH, alkanility, concentrations of dissolved inorganic carbon, dissolved and total organic carbon, methane, dimethylsulfoniopropionate, nutrients, carbohydrates, and amino acids were analyzed in the seawater samples. Concentrations of total organic carbon, six constant elements and nine trace elements were determined in the sediment samples. All the vertical profiles of the chemical parameters in the seawater have unique characteristics. Our resluts also showed that the carbonate compensation depth (CCD) was between 4500 m and 5000 m in the trench. The hadal sediment at 6500 m depth under the CCD line was siliceous ooze favored for the burial of orgaic carbon, attributed to accumulation of surface sediment by gravity flow. The abyssal sediment at the 4500 m depth was calcareous ooze. Various microfossils, such as discoasters and diatoms, were identified in different sediment layers of the sediment samples.Based on the ratios of Fe/Al and Ti/Al, and the correlation between different elements, the sediment in the Yap Trench were derived from biogenic, terrestrial, volcanic and autogenic sources. The ratios of Ni/Co and V/Cr showed that the deposition environment of the trench should be oxidative, arributed to inflow of the Antractic bottom oxygen-rich seawater.The high concentraiont of Ca in the sediment from the station 371-Yap-S02 below 4 cm depth indicated that there was no large-scale volcanic eruption in the research area and the volcanic materials in the sediment might orginated from the Mariana Volcanic Arc, and the Carolyn Ridge has been slowly sinking on the east side of the trench due to plate subduction. This study is the first systematic study of chemical characteristics in the seawater and sediment of the Yap Trench.

A Large-scale Finite Element Model on Micromechanical Damage and Failure of Carbon Fiber/Epoxy Composites Including Thermal Residual Stress

NASA Astrophysics Data System (ADS)

Liu, P. F.; Li, X. K.

2018-06-01

The purpose of this paper is to study micromechanical progressive failure properties of carbon fiber/epoxy composites with thermal residual stress by finite element analysis (FEA). Composite microstructures with hexagonal fiber distribution are used for the representative volume element (RVE), where an initial fiber breakage is assumed. Fiber breakage with random fiber strength is predicted using Monte Carlo simulation, progressive matrix damage is predicted by proposing a continuum damage mechanics model and interface failure is simulated using Xu and Needleman's cohesive model. Temperature dependent thermal expansion coefficients for epoxy matrix are used. FEA by developing numerical codes using ANSYS finite element software is divided into two steps: 1. Thermal residual stresses due to mismatch between fiber and matrix are calculated; 2. Longitudinal tensile load is further exerted on the RVE to perform progressive failure analysis of carbon fiber/epoxy composites. Numerical convergence is solved by introducing the viscous damping effect properly. The extended Mori-Tanaka method that considers interface debonding is used to get homogenized mechanical responses of composites. Three main results by FEA are obtained: 1. the real-time matrix cracking, fiber breakage and interface debonding with increasing tensile strain is simulated. 2. the stress concentration coefficients on neighbouring fibers near the initial broken fiber and the axial fiber stress distribution along the broken fiber are predicted, compared with the results using the global and local load-sharing models based on the shear-lag theory. 3. the tensile strength of composite by FEA is compared with those by the shear-lag theory and experiments. Finally, the tensile stress-strain curve of composites by FEA is applied to the progressive failure analysis of composite pressure vessel.

A Large-scale Finite Element Model on Micromechanical Damage and Failure of Carbon Fiber/Epoxy Composites Including Thermal Residual Stress

NASA Astrophysics Data System (ADS)

Liu, P. F.; Li, X. K.

2017-09-01

The purpose of this paper is to study micromechanical progressive failure properties of carbon fiber/epoxy composites with thermal residual stress by finite element analysis (FEA). Composite microstructures with hexagonal fiber distribution are used for the representative volume element (RVE), where an initial fiber breakage is assumed. Fiber breakage with random fiber strength is predicted using Monte Carlo simulation, progressive matrix damage is predicted by proposing a continuum damage mechanics model and interface failure is simulated using Xu and Needleman's cohesive model. Temperature dependent thermal expansion coefficients for epoxy matrix are used. FEA by developing numerical codes using ANSYS finite element software is divided into two steps: 1. Thermal residual stresses due to mismatch between fiber and matrix are calculated; 2. Longitudinal tensile load is further exerted on the RVE to perform progressive failure analysis of carbon fiber/epoxy composites. Numerical convergence is solved by introducing the viscous damping effect properly. The extended Mori-Tanaka method that considers interface debonding is used to get homogenized mechanical responses of composites. Three main results by FEA are obtained: 1. the real-time matrix cracking, fiber breakage and interface debonding with increasing tensile strain is simulated. 2. the stress concentration coefficients on neighbouring fibers near the initial broken fiber and the axial fiber stress distribution along the broken fiber are predicted, compared with the results using the global and local load-sharing models based on the shear-lag theory. 3. the tensile strength of composite by FEA is compared with those by the shear-lag theory and experiments. Finally, the tensile stress-strain curve of composites by FEA is applied to the progressive failure analysis of composite pressure vessel.

Evaluation of elemental enrichments in surface sediments off southwestern Taiwan

NASA Astrophysics Data System (ADS)

Chen, Chen-Tung; Kandasamy, Selvaraj

2008-05-01

Surface slices of 20 sediment cores, off southwestern Taiwan, and bed sediment of River Kaoping were measured for major and trace elements (Al, As, Ca, Cd, Cl, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, P, Pb, S, Si, Ti, V, and Zn) to evaluate the geochemical processes responsible for their distribution, including elemental contamination. Major element/Al ratio and mean grain size indicate quartz-dominated, coarse grained sediments that likely derived from sedimentary rocks of Taiwan and upper crust of Yangtze Craton. Bi-plot of SiO2 versus Fe2O{3/T} suggests the possible iron enrichment in sediments of slag dumping sites. Highest concentrations of Cr, Mn, P, S, and Zn found in sediments of dumping sites support this. Correlation analysis shows dual associations, detrital and organic carbon, for Cr, P, S, and V with the latter association typical for sediments in dumping sites. Normalization of trace elements to Al indicates high enrichment factors (>2) for As, Cd, Pb, and Zn, revealing contamination. Factor analysis extracted four geochemical associations with the principal factor accounted for 25.1% of the total variance and identifies the combined effects of dumped iron and steel slag-induced C-S-Fe relationship owing to authigenic precipitation of Fe-Mn oxyhydroxides and/or metal sulfides, and organic matter complexation of Fe, Mn, Ca, Cr, P, and V. Factors 2, 3, and 4 reveal detrital association (Ti, Al, Ni, Pb, Cu, and V), effect of sea salt (Cl, Mg, Na, and K) and anthropogenic component (As and Zn)-carbonate link, respectively, in the investigated sediments.

Development of a low-cost biogas filtration system to achieve higher-power efficient AC generator

NASA Astrophysics Data System (ADS)

Mojica, Edison E.; Ardaniel, Ar-Ar S.; Leguid, Jeanlou G.; Loyola, Andrea T.

2018-02-01

The paper focuses on the development of a low-cost biogas filtration system for alternating current generator to achieve higher efficiency in terms of power production. A raw biogas energy comprises of 57% combustible element and 43% non-combustible elements containing carbon dioxide (36%), water vapor (5%), hydrogen sulfide (0.5%), nitrogen (1%), oxygen (0 - 2%), and ammonia (0 - 1%). The filtration system composes of six stages: stage 1 is the water scrubber filter intended to remove the carbon dioxide and traces of hydrogen sulfide; stage 2 is the silica gel filter intended to reduce the water vapor; stage 3 is the iron sponge filter intended to remove the remaining hydrogen sulfide; stage 4 is the sodium hydroxide solution filter intended to remove the elemental sulfur formed during the interaction of the hydrogen sulfide and the iron sponge and for further removal of carbon dioxide; stage 5 is the silica gel filter intended to further eliminate the water vapor gained in stage 4; and, stage 6 is the activated carbon filter intended to remove the carbon dioxide. The filtration system was able to lower the non-combustible elements by 72% and thus, increasing the combustible element by 54.38%. The unfiltered biogas is capable of generating 16.3 kW while the filtered biogas is capable of generating 18.6 kW. The increased in methane concentration resulted to 14.11% increase in the power output. The outcome resulted to better engine performance in the generation of electricity.

Source Apportionment of PM2.5 Mass and Optical Attenuation Over an Ecologically Sensitive Zone in Central India by Positive Matrix Factorization

NASA Astrophysics Data System (ADS)

Nirmalkar, J.; Raman, R. S.

2016-12-01

Ambient PM2.5 samples (N=366) were collected over an ecologically sensitive zone (Van Vihar National Park) in Bhopal, Central India for two years (01 January, 2012 to 31 December, 2013). Samples were collected using three co-located Mini-Vol® samplers on Teflon, Nylon, and Quartz filter substrates. The aerosol was then chemically characterized for water-soluble inorganic ions, elements, and carbon fractions (elemental carbon and organic carbon) using ion chromatography, ED-XRF, and thermal-optical EC/OC analyzer, respectively. The optical attenuation (at 370 nm and 800 nm) of PM2.5 aerosols was also determined by optical transmissometry (OT-21). The application of Positive matrix factorization (PMF) to a combination of PM2.5 mass, its ions, elements, carbon fractions, and optical attenuation and its outcomes will be discussed.

Element budgets in an Arctic mesocosm CO2 perturbation study

NASA Astrophysics Data System (ADS)

Czerny, J.; Schulz, K. G.; Boxhammer, T.; Bellerby, R. G. J.; Büdenbender, J.; Engel, A.; Krug, S. A.; Ludwig, A.; Nachtigall, K.; Nondal, G.; Niehoff, B.; Siljakova, A.; Riebesell, U.

2012-08-01

Recent studies on the impacts of ocean acidification on pelagic communities have identified changes in carbon to nutrient dynamics with related shifts in elemental stoichiometry. In principle, mesocosm experiments provide the opportunity of determining the temporal dynamics of all relevant carbon and nutrient pools and, thus, calculating elemental budgets. In practice, attempts to budget mesocosm enclosures are often hampered by uncertainties in some of the measured pools and fluxes, in particular due to uncertainties in constraining air/sea gas exchange, particle sinking, and wall growth. In an Arctic mesocosm study on ocean acidification using KOSMOS (Kiel Off-Shore Mesocosms for future Ocean Simulation) all relevant element pools and fluxes of carbon, nitrogen and phosphorus were measured, using an improved experimental design intended to narrow down some of the mentioned uncertainties. Water column concentrations of particulate and dissolved organic and inorganic constituents were determined daily. New approaches for quantitative estimates of material sinking to the bottom of the mesocosms and gas exchange in 48 h temporal resolution, as well as estimates of wall growth were developed to close the gaps in element budgets. Future elevated pCO2 was found to enhance net autotrophic community carbon uptake in 2 of the 3 experimental phases but did not significantly affect particle elemental composition. Enhanced carbon consumption appears to result in accumulation of dissolved organic compounds under nutrient recycling summer conditions. This carbon over-consumption effect becomes evident from budget calculations, but was too small to be resolved by direct measurements of dissolved organics. The out-competing of large diatoms by comparatively small algae in nutrient uptake caused reduced production rates under future ocean CO2 conditions in the end of the experiment. This CO2 induced shift away from diatoms towards smaller phytoplankton and enhanced cycling of dissolved organics was pushing the system towards a retention type food chain with overall negative effects on export potential.

Soil Data from a Moderately Well and Somewhat Poorly Drained Fire Chronosequence near Thompson, Manitoba, Canada

USGS Publications Warehouse

Manies, K.L.; Harden, J.W.; Veldhuis, Hugo; Trumbore, Sue

2006-01-01

The U.S. Geological Survey project Fate of Carbon in Alaskan Landscapes (FOCAL) is studying the effect of fire and soil drainage on soil carbon storage in the boreal forest. As such this group was invited to be a part of a NSF-funded project (Fire, Ecosystem and Succession - Experiment Boreal or FIRES-ExB) to study the carbon balance of sites that varied in age (time since fire) and soil drainage in the Thompson, Manitoba, Canada region. This report describes the location of our FIRES-ExB sampling sites as well as the procedures used to describe, sample, and analyze the soils. This report also contains data tables with sample related information including, but not limited to, field descriptions, bulk density, particle size distribution, moisture content, carbon (C) concentration, nitrogen (N) concentration, isotopic data for C, and major, minor and trace elemental concentration.

Technical Report Series on Global Modeling and Data Assimilation. Volume 42; Soil Moisture Active Passive (SMAP) Project Calibration and Validation for the L4_C Beta-Release Data Product

NASA Technical Reports Server (NTRS)

Koster, Randal D. (Editor); Kimball, John S.; Jones, Lucas A.; Glassy, Joseph; Stavros, E. Natasha; Madani, Nima (Editor); Reichle, Rolf H.; Jackson, Thomas; Colliander, Andreas

2015-01-01

During the post-launch Cal/Val Phase of SMAP there are two objectives for each science product team: 1) calibrate, verify, and improve the performance of the science algorithms, and 2) validate accuracies of the science data products as specified in the L1 science requirements according to the Cal/Val timeline. This report provides analysis and assessment of the SMAP Level 4 Carbon (L4_C) product specifically for the beta release. The beta-release version of the SMAP L4_C algorithms utilizes a terrestrial carbon flux model informed by SMAP soil moisture inputs along with optical remote sensing (e.g. MODIS) vegetation indices and other ancillary biophysical data to estimate global daily NEE and component carbon fluxes, particularly vegetation gross primary production (GPP) and ecosystem respiration (Reco). Other L4_C product elements include surface (<10 cm depth) soil organic carbon (SOC) stocks and associated environmental constraints to these processes, including soil moisture and landscape FT controls on GPP and Reco (Kimball et al. 2012). The L4_C product encapsulates SMAP carbon cycle science objectives by: 1) providing a direct link between terrestrial carbon fluxes and underlying freeze/thaw and soil moisture constraints to these processes, 2) documenting primary connections between terrestrial water, energy and carbon cycles, and 3) improving understanding of terrestrial carbon sink activity in northern ecosystems.

Carbon footprint assessment of recycling technologies for rare earth elements: A case study of recycling yttrium and europium from phosphor.

PubMed

Hu, Allen H; Kuo, Chien-Hung; Huang, Lance H; Su, Chao-Chin

2017-02-01

Rare earth elements are key raw materials in high-technology industries. Mining activities and manufacturing processes of such industries have caused considerable environmental impacts, such as soil erosion, vegetation destruction, and various forms of pollution. Sustaining the long-term supply of rare earth elements is difficult because of the global shortage of rare earth resources. The diminishing supply of rare earth elements has attracted considerable concern because many industrialized countries regarded such elements as important strategic resources for economic growth. This study aims to explore the carbon footprints of yttrium and europium recovery techniques from phosphor. Two extraction recovery methods, namely, acid extraction and solvent extraction, were selected for the analysis and comparison of carbon footprints. The two following functional units were used: (1) the same phosphor amounts for specific Y and Eu recovery concentrations, and (2) the same phosphor amounts for extraction. For acid extraction method, two acidic solutions (H 2 SO 4 and HCl) were used at two different temperatures (60 and 90°C). For solvent extraction method, acid leaching was performed followed by ionic liquid extraction. Carbon footprints from acid and solvent extraction methods were estimated to be 10.1 and 10.6kgCO 2 eq, respectively. Comparison of the carbon emissions of the two extraction methods shows that the solvent extraction method has significantly higher extraction efficiency, even though acid extraction method has a lower carbon footprint. These results may be used to develop strategies for life cycle management of rare earth resources to realize sustainable usage. Copyright © 2016 Elsevier Ltd. All rights reserved.

Wet scavenging of organic and elemental carbon during summer monsoon and winter monsoon seasons

NASA Astrophysics Data System (ADS)

Sonwani, S.; Kulshrestha, U. C.

2017-12-01

In the era of rapid industrialization and urbanization, atmospheric abundance of carbonaceous aerosols is increasing due to more and more fossil fuel consumption. Increasing levels of carbonaceous content have significant adverse effects on air quality, human health and climate. The present study was carried out at Delhi covering summer monsoon (July -Sept) and winter monsoon (Dec-Jan) seasons as wind and other meteorological factors affect chemical composition of precipitation in different manner. During the study, the rainwater and PM10 aerosols were collected in order to understand the scavenging process of elemental and organic carbon. The Rain water samples were collected on event basis. PM10 samples were collected before rain (PR), during rain (DR) and after rain (AR) during 2016-2017. The collected samples were analysed by the thermal-optical reflectance method using IMPROVE-A protocol. In PM10, the levels of organic carbon (OC) and its fractions (OC1, OC2, OC3 and OC4) were found significantly lower in the AR samples as compared to PR and DR samples. A significant positive correlation was noticed between scavenging ratios of organic carbon and rain intensity indicating an efficient wet removal of OC. In contrast to OCs, the levels of elemental carbon and its fractions (EC1, EC2, and EC3) in AR were not distinct during PR and DR. The elemental carbon showed very week correlation with rain intensity in Delhi region which could be explained on the basis of hydrophobic nature of freshly emitted carbon soot. The detailed results will be discussed during the conference.

Electrical and thermal conductivity of Fe-C alloy at high pressure: implications for effects of carbon on the geodynamo of the Earth's core

NASA Astrophysics Data System (ADS)

Zhang, C.; Lin, J. F.; Liu, Y.; Feng, S.; Jin, C.; Yoshino, T.

2017-12-01

Thermal conductivity of iron alloy in the Earth's core plays a crucial role in constraining the energetics of the geodynamo and the thermal evolution of the planet. Studies on the thermal conductivity of iron reveal the importance of the effects of light elements and high temperature. Carbon has been proposed to be a candidate light element in Earth's core for its meteoritic abundance and high-pressure velocity-density profiles of iron carbides (e.g., Fe7C3). In this study, we employed four-probe van der Pauw method in a diamond anvil cell to measure the electrical resistivity of pure iron, iron carbon alloy, and iron carbides at high pressures. These studies were complimented with synchrotron X-ray diffraction and focused ion beam (FIB) analyses. Our results show significant changes in the electrical conductivity of these iron-carbon alloys that are consistent previous reports with structural and electronic transitions at high pressures, indicating that these transitions should be taken into account in evaluating the electrical and thermal conductivity at high pressure. To apply our results to understand the thermal conduction in the Earth's core, we have compared our results with literature values for the electrical and thermal conductivity of iron alloyed with light elements (C, Si) at high pressures. These comparisons permit the validity of the Wiedemann-Franz law and Matthiessen's rule for the effects of light elements on the thermal conductivity of the Earth's core. We found that an addition of a light element such as carbon has an strong effect on the reducing the thermal conductivity of Earth's core, but the magnitude of the alloying effect strongly depends on the identity of the light element and the crystal and electronic structures. Based on our results and literature values, we have modelled the electrical and thermal conductivity of iron-carbon alloy at Earth's core pressure-temperature conditions to the effects on the heat flux in the Earth's core. In this presentation, we will address how carbon as a potential light element in the Earth's core can significantly affect our view of the heat flux across the core-mantle boundary and geodynamo of our planet.

Generation, capture, and utilization of industrial carbon dioxide.

PubMed

Hunt, Andrew J; Sin, Emily H K; Marriott, Ray; Clark, James H

2010-03-22

As a carbon-based life form living in a predominantly carbon-based environment, it is not surprising that we have created a carbon-based consumer society. Our principle sources of energy are carbon-based (coal, oil, and gas) and many of our consumer goods are derived from organic (i.e., carbon-based) chemicals (including plastics, fabrics and materials, personal care and cleaning products, dyes, and coatings). Even our large-volume inorganic-chemicals-based industries, including fertilizers and construction materials, rely on the consumption of carbon, notably in the form of large amounts of energy. The environmental problems which we now face and of which we are becoming increasingly aware result from a human-induced disturbance in the natural carbon cycle of the Earth caused by transferring large quantities of terrestrial carbon (coal, oil, and gas) to the atmosphere, mostly in the form of carbon dioxide. Carbon is by no means the only element whose natural cycle we have disturbed: we are transferring significant quantities of elements including phosphorus, sulfur, copper, and platinum from natural sinks or ores built up over millions of years to unnatural fates in the form of what we refer to as waste or pollution. However, our complete dependence on the carbon cycle means that its disturbance deserves special attention, as is now manifest in indicators such as climate change and escalating public concern over global warming. As with all disturbances in materials balances, we can seek to alleviate the problem by (1) dematerialization: a reduction in consumption; (2) rematerialization: a change in what we consume; or (3) transmaterialization: changing our attitude towards resources and waste. The "low-carbon" mantra that is popularly cited by organizations ranging from nongovernmental organizations to multinational companies and from local authorities to national governments is based on a combination of (1) and (2) (reducing carbon consumption though greater efficiency and lower per capita consumption, and replacing fossil energy sources with sources such as wind, wave, and solar, respectively). "Low carbon" is of inherently less value to the chemical and plastics industries at least in terms of raw materials although a version of (2), the use of biomass, does apply, especially if we use carbon sources that are renewable on a human timescale. There is however, another renewable, natural source of carbon that is widely available and for which greater utilization would help restore material balance and the natural cycle for carbon in terms of resource and waste. CO(2), perhaps the most widely discussed and feared chemical in modern society, is as fundamental to our survival as water, and like water we need to better understand the human as well as natural production and consumption of CO(2) so that we can attempt to get these into a sustainable balance. Current utilization of this valuable resource by the chemical industry is only 90 megatonne per year, compared to the 26.3 gigatonne CO(2) generated annually by combustion of fossil fuels for energy generation, as such significant opportunities exist for increased utilization of CO(2) generated from industrial processes. It is also essential that renewable energy is used if CO(2) is to be utilized as a C1 building block.

Integrating Remote Sensing, Field Observations, and Models to Understand Disturbance and Climate Effects on the Carbon Balance of the West Coast U.S.

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

Cohen, Warren

2014-07-03

As an element of NACP research, the proposed investigation is a two pronged approach that derives and evaluates a regional carbon (C) budget for Oregon, Washington, and California. Objectives are (1) Use multiple data sources, including AmeriFlux data, inventories, and multispectral remote sensing data to investigate trends in carbon storage and exchanges of CO2 and water with variation in climate and disturbance history; (2) Develop and apply regional modeling that relies on these multiple data sources to reduce uncertainty in spatial estimates of carbon storage and NEP, and relative contributions of terrestrial ecosystems and anthropogenic emissions to atmospheric CO2 inmore » the region; (3) Model terrestrial carbon processes across the region, using the Biome-BGC terrestrial ecosystem model, and an atmospheric inverse modeling approach to estimate variation in rate and timing of terrestrial uptake and feedbacks to the atmosphere in response to climate and disturbance.« less

Integrating Remote Sensing, Field Observations, and Models to Understand Disturbance and Climate Effects on the Carbon Balance of the West Coast U.S., Final Report

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

Beverly E. Law

2011-10-05

As an element of NACP research, the proposed investigation is a two pronged approach that derives and evaluates a regional carbon (C) budget for Oregon, Washington, and California. Objectives are (1) Use multiple data sources, including AmeriFlux data, inventories, and multispectral remote sensing data to investigate trends in carbon storage and exchanges of CO2 and water with variation in climate and disturbance history; (2) Develop and apply regional modeling that relies on these multiple data sources to reduce uncertainty in spatial estimates of carbon storage and NEP, and relative contributions of terrestrial ecosystems and anthropogenic emissions to atmospheric CO2 inmore » the region; (3) Model terrestrial carbon processes across the region, using the Biome-BGC terrestrial ecosystem model, and an atmospheric inverse modeling approach to estimate variation in rate and timing of terrestrial uptake and feedbacks to the atmosphere in response to climate and disturbance.« less

The effects of phosphorus limitation on carbon metabolism in diatoms.

PubMed

Brembu, Tore; Mühlroth, Alice; Alipanah, Leila; Bones, Atle M

2017-09-05

Phosphorus is an essential element for life, serving as an integral component of nucleic acids, lipids and a diverse range of other metabolites. Concentrations of bioavailable phosphorus are low in many aquatic environments. Microalgae, including diatoms, apply physiological and molecular strategies such as phosphorus scavenging or recycling as well as adjusting cell growth in order to adapt to limiting phosphorus concentrations. Such strategies also involve adjustments of the carbon metabolism. Here, we review the effect of phosphorus limitation on carbon metabolism in diatoms. Two transcriptome studies are analysed in detail, supplemented by other transcriptome, proteome and metabolite data, to gain an overview of different pathways and their responses. Phosphorus, nitrogen and silicon limitation responses are compared, and similarities and differences discussed. We use the current knowledge to propose a suggestive model for the carbon flow in phosphorus-replete and phosphorus-limited diatom cells.This article is part of the themed issue 'The peculiar carbon metabolism in diatoms'. © 2017 The Authors.

The effects of phosphorus limitation on carbon metabolism in diatoms

PubMed Central

Alipanah, Leila

2017-01-01

Phosphorus is an essential element for life, serving as an integral component of nucleic acids, lipids and a diverse range of other metabolites. Concentrations of bioavailable phosphorus are low in many aquatic environments. Microalgae, including diatoms, apply physiological and molecular strategies such as phosphorus scavenging or recycling as well as adjusting cell growth in order to adapt to limiting phosphorus concentrations. Such strategies also involve adjustments of the carbon metabolism. Here, we review the effect of phosphorus limitation on carbon metabolism in diatoms. Two transcriptome studies are analysed in detail, supplemented by other transcriptome, proteome and metabolite data, to gain an overview of different pathways and their responses. Phosphorus, nitrogen and silicon limitation responses are compared, and similarities and differences discussed. We use the current knowledge to propose a suggestive model for the carbon flow in phosphorus-replete and phosphorus-limited diatom cells. This article is part of the themed issue ‘The peculiar carbon metabolism in diatoms’. PMID:28717016

A Multi-Proxy Investigation into the Biomineralization Pathways of Benthic Invertebrate Taxa

NASA Astrophysics Data System (ADS)

DeCorte, I. A.; Liu, Y. W.; Doss, W. C.; Ries, J. B.; Eagle, R.

2016-12-01

Ocean acidification is the result of surface ocean absorption of anthropogenic carbon dioxide emissions and endangers many marine organisms. Decreases in pH and a coupled reduction in CaCO3 saturation state have been shown to disrupt the process of biomineralization within many species of marine calcifiers. Recent studies, however, demonstrate that calcifying organisms respond in diverse ways to changes in pH and CaCO3 saturation state. We examine element ratios (including Sr/Ca, Mg/Ca, Li/Ca, and B/Ca) and boron isotope ratios (δ11B) in 7 macro-invertebrate species (blue crab, shrimp, coralline red algae, pencil urchin, purple urchin, temperate coral, and serpulid worm) and compare results to net calcification rates and experimental seawater carbonate system parameters. Correlations between seawater carbonate chemistry and the elemental compositions of biogenic calcite and aragonite vary widely and are highly taxon-specific, ranging from strongly correlated to no significant response—a finding that is consistent with mounting evidence that many marine calcifying organisms regulate the chemistry of the fluid at their site of calcification. A Rayleigh framework is used to interpret the elemental data. We then analyze δ11B of the same samples as a proxy for pH at their site of calcification. Preliminary results suggest that coralline red algae, shrimp, urchin, serpulid worm and temperate coral taxa elevate pH at the site of calcification relative to the organism's ambient seawater. We plan to utilize a multi-proxy approach to examine the biomineralization pathways that influence elemental and boron isotope fractionation during calcification and precipitation of biogenic aragonite and calcite. A better understanding of these biomineralization pathways will help us to predict the responses of benthic invertebrate taxa to ocean acidification, as well as provide insights into drivers of so-called vital effects on elemental and stable boron isotope fractionation within biogenic carbonates—thereby assessing the fidelity of these proxies for reconstructing paleo-environmental change within a diverse range of marine calcifiers.

Carbon and sulfur distributions and abundances in lunar fines

NASA Technical Reports Server (NTRS)

Gibson, E. K., Jr.; Moore, G. W.

1973-01-01

Total sulfur abundances have been determined for 20 Apollo 14, 15, and 16 soil samples and one Apollo 14 breccia. Sulfur concentrations range from 474 to 844 microg S/g. Volatilization experiments on selected samples have been carried out using step-wise heating. Sample residues have been analyzed for their total carbon and sulfur abundances to establish the material balance in lunar fines for these two elements. Volatilization experiments have established that between 31 to 54 microg C/g remains in soils which have been heated at 1100 C for 24 hours under vacuum. The residual carbon is believed to be indigenous lunar carbon whereas all forms of carbon lost from samples below 1100 C is extralunar carbon. Total carbon and sulfur abundances taken from the literature have been used to show the depletion of volatile elements with increasing grade for the Apollo 14 breccias.

Minor-element composition and organic carbon content of marine and nonmarine shales of Late Cretaceous age in the western interior of the United States

USGS Publications Warehouse

Tourtelot, H.A.

1964-01-01

The composition of nonmarine shales of Cretaceous age that contain less than 1 per cent organic carbon is assumed to represent the inherited minor-element composition of clayey sediments delivered to the Cretaceous sea that occupied the western interior region of North America. Differences in minor-element content between these samples and samples of 1. (a) nonmarine carbonaceous shales (1 to 17 per cent organic carbon), 2. (b) nearshore marine shales (less than 1 per cent organic carbon), and 3. (c) offshore marine shales (as much as 8 per cent organic carbon), all of the same age, reveal certain aspects of the role played by clay minerals and organic materials in affecting the minor-element composition of the rocks. The organic carbon in the nonmarine rocks occurs in disseminated coaly plant remains. The organic carbon in the marine rocks occurs predominantly in humic material derived from terrestrial plants. The close similarity in composition between the organic isolates from the marine samples and low-rank coal suggests that the amount of marine organic material in these rocks is small. The minor-element content of the two kinds of nonmarine shales is the same despite the relatively large amount of organic carbon in the carbonaceous shales. The nearshore marine shales, however, contain larger median amounts of arsenic, boron, chromium, vanadium and zinc than do the nonmarine rocks; and the offshore marine shales contain even larger amounts of these elements. Cobalt, molybdenum, lead and zirconium show insignificant differences in median content between the nonmarine and marine rocks, although as much as 25 ppm molybdenum is present in some offshore marine samples. The gallium content is lower in the marine than in the nonmarine samples. Copper and selenium contents of the two kinds of nonmarine rocks and the nearshore marine samples are the same, but those of the offshore samples are larger. In general, arsenic, chromium, copper, molybdenum, selenium, vanadium and zinc are concentrated in those offshore marine samples having the largest amounts of organic carbon, but samples with equal amounts of vanadium, for instance, may differ by a factor of 3 in their amount of organic carbon. Arsenic and molybdenum occur in some samples chiefly in syngenetic pyrite but also are present in relatively large amounts in samples that contain little pyrite. The data on nonmarine carbonaceous shales indicate that organic matter of terrestrial origin in marine shales contributes little to the minor-element content of such rocks. It is possible that marine organic matter, even though seemingly small in amount in marine shales, contributes to the minor-element composition of the shales. In addition to any such contribution, however, the great effectiveness in sorption processes of humic materials in conjunction with clay minerals suggests that such processes must have played an important role as these materials moved from the relatively dilute solutions of the nonmarine environment to the relatively concentrated solution of sea water. The volumes of sea water sufficient to supply for sorption the amounts of most minor elements in the offshore marine samples are insignificant compared to the volumes of water with which the clay and organic matter were in contact during their transportation and sedimentation. Consequently, the chemical characteristics of the environment in which the clay minerals and organic matter accumulated and underwent diagenesis probably were the most important factors in controlling the degree to which sorption processes and the formation of syngenetic minerals affected the final composition of the rocks. ?? 1969.

Element distribution patterns in the ordovician Galena group, Southeastern Minnesota: Indicators of fluid flow and provenance of terrigenous material

USGS Publications Warehouse

Lively, R.S.; Morey, G.B.; Mossler, J.H.

1997-01-01

As part of a regional geochemical investigation of lower Paleozoic strata in the Hollandale embayment of southeastern Minnesota, elemental concentrations in acid-insoluble residues were determined for carbonate rock in the Middle Ordovician Galena Group. Elemental distribution patterns within the insoluble residues, particularly those of Ti, Al, and Zr, show that the Wisconsin dome and the Wisconsin arch, which contributed sediment to the embayment prior to Galena time, continued as weak sources of sediment during this period. In contrast, trace metals commonly associated with Mississippi Valley-type lead-zinc mineralization, including Pb, Zn, Cu, Ag, Ni, Co, As, and Mo, show dispersal patterns that are independent of those associated with primary depositional phenomena. These trace metals are concentrated in southern Minnesota in carbonate rocks near the interface between limestone- and dolostone-dominated strata. Dispersal patterns imply that the metals were carried by a north-flowing regional ground-water system. The results show that the geochemical attributes of insoluble residues can be used to distinguish provenance and transport directions of primary sediments within a depositional basin from effects of subsequent regional ground-water flow systems.

Finite element investigation of temperature dependence of elastic properties of carbon nanotube reinforced polypropylene

NASA Astrophysics Data System (ADS)

Ahmadi, Masoud; Ansari, Reza; Rouhi, Saeed

2017-11-01

This paper aims to investigate the elastic modulus of the polypropylene matrix reinforced by carbon nanotubes at different temperatures. To this end, the finite element approach is employed. The nanotubes with different volume fractions and aspect ratios (the ratio of length to diameter) are embedded in the polymer matrix. Besides, random and regular algorithms are utilized to disperse carbon nanotubes in the matrix. It is seen that as the pure polypropylene, the elastic modulus of carbon nanotube reinforced polypropylene decreases by increasing the temperature. It is also observed that when the carbon nanotubes are dispersed parallelly and the load is applied along the nanotube directions, the largest improvement in the elastic modulus of the nanotube/polypropylene nanocomposites is obtained.

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.

Conversion of calcium sulphide to calcium carbonate during the process of recovery of elemental sulphur from gypsum waste.

PubMed

de Beer, M; Maree, J P; Liebenberg, L; Doucet, F J

2014-11-01

The production of elemental sulphur and calcium carbonate (CaCO3) from gypsum waste can be achieved by thermally reducing the waste into calcium sulphide (CaS), which is then subjected to a direct aqueous carbonation step for the generation of hydrogen sulphide (H2S) and CaCO3. H2S can subsequently be converted to elemental sulphur via the commercially available chemical catalytic Claus process. This study investigated the carbonation of CaS by examining both the solution chemistry of the process and the properties of the formed carbonated product. CaS was successfully converted into CaCO3; however, the reaction yielded low-grade carbonate products (i.e. <90 mass% as CaCO3) which comprised a mixture of two CaCO3 polymorphs (calcite and vaterite), as well as trace minerals originating from the starting material. These products could replace the Sappi Enstra CaCO3 (69 mass% CaCO3), a by-product from the paper industry which is used in many full-scale AMD neutralisation plants but is becoming insufficient. The insight gained is now also being used to develop and optimize an indirect aqueous CaS carbonation process for the production of high-grade CaCO3 (i.e. >99 mass% as CaCO3) or precipitated calcium carbonate (PCC). Copyright © 2014 Elsevier Ltd. All rights reserved.

[Ultra-Fine Pressed Powder Pellet Sample Preparation XRF Determination of Multi-Elements and Carbon Dioxide in Carbonate].

PubMed

Li, Xiao-li; An, Shu-qing; Xu, Tie-min; Liu, Yi-bo; Zhang, Li-juan; Zeng, Jiang-ping; Wang, Na

2015-06-01

The main analysis error of pressed powder pellet of carbonate comes from particle-size effect and mineral effect. So in the article in order to eliminate the particle-size effect, the ultrafine pressed powder pellet sample preparation is used to the determination of multi-elements and carbon-dioxide in carbonate. To prepare the ultrafine powder the FRITSCH planetary Micro Mill machine and tungsten carbide media is utilized. To conquer the conglomeration during the process of grinding, the wet grinding is preferred. The surface morphology of the pellet is more smooth and neat, the Compton scatter effect is reduced with the decrease in particle size. The intensity of the spectral line is varied with the change of the particle size, generally the intensity of the spectral line is increased with the decrease in the particle size. But when the particle size of more than one component of the material is decreased, the intensity of the spectral line may increase for S, Si, Mg, or decrease for Ca, Al, Ti, K, which depend on the respective mass absorption coefficient . The change of the composition of the phase with milling is also researched. The incident depth of respective element is given from theoretical calculation. When the sample is grounded to the particle size of less than the penetration depth of all the analyte, the effect of the particle size on the intensity of the spectral line is much reduced. In the experiment, when grounded the sample to less than 8 μm(d95), the particle-size effect is much eliminated, with the correction method of theoretical α coefficient and the empirical coefficient, 14 major, minor and trace element in the carbonate can be determined accurately. And the precision of the method is much improved with RSD < 2%, except Na2O. Carbon is ultra-light element, the fluorescence yield is low and the interference is serious. With the manual multi-layer crystal PX4, coarse collimator, empirical correction, X-ray spectrometer can be used to determine the carbon dioxide in the carbonate quantitatively. The intensity of the carbon is increase with the times of the measurement and the time delay even the pellet is stored in the dessicator. So employing the latest pressed powder pellet is suggested.

Novel Platform Development Using an Assembly of Carbon Nanotube, Nanogold and Immobilized RNA Capture Element Towards Rapid, Selective Sensing of Bacteria

DTIC Science & Technology

2012-06-12

Doped Polyaniline/Carbon Nanotube Composite for Sensitive and Selective Detection of the Neurotransmitter Dopamine . Anal. Chem. 2007, 79, 2583–2587...biosensor with aptamers as bio-recognition element. Sensors 2010, 10, 5859–5871. Sensors 2012, 12 8144 14. Hernandez, F.J.; Ozalp, V.C. Graphene

Boron Clusters Come of Age

ERIC Educational Resources Information Center

Grimes, Russell N.

2004-01-01

Boron is the only element other than carbon that can build molecules of unlimited size by covalently boding to itself, a property known as catenation. In contrast to the chains and rings favored by carbon, boron arguably adopts a cluster motif that is reflected in the various forms of the pure element and in the huge area of polyhedral borane…

THE EFFECT OF WATER (VAPOR-PHASE) AND CARBON ON ELEMENTAL MERCURY REMOVAL IN A FLOW REACTOR

EPA Science Inventory

The paper gives results of studying the effect of vapor-phase moisture on elemental mercury (Hgo) removal by activated carbon (AC) in a flow reactor. tests involved injecting AC into both a dry and a 4% moisture nitrogen (N2) /Hgo gas stream. A bituminous-coal-based AC (Calgon WP...

RELATING PERSONAL PM AND PM-ASSOCIATED ELEMENTAL CARBON EXPOSURES TO CARDIOVASCULAR AND PULMONARY SYMPTOMS IN A HIGH-RISK SUBPOLULATION

EPA Science Inventory

Sensitive subpopulations such as COPD patients have been shown to be especially susceptible to the effects of PM exposure. Proximity to traffic has been shown to be a predictor of PM effects in susceptible populations. Elemental carbon (EC) has been demonstrated to be a good ...

Chemistry Characterization of Jet Aircraft Engine Particulate by XPS: Results from APEX III

NASA Technical Reports Server (NTRS)

Vander Wal, Randy L.; Bryg, Victoria M.

2014-01-01

This paper reports XPS analysis of jet exhaust particulate from a B737, Lear, ERJ, and A300 aircraft during the APEX III NASA led field campaign. Carbon hybridization and bonding chemistry are identified by high-resolution scans about the C1s core-shell region. Significant organic content as gauged by the sp3/sp2 ratio is found across engines and platforms. Polar oxygen functional groups include carboxylic, carbonyl and phenol with combined content of 20 percent or more. By lower resolution survey scans various elements including transition metals are identified along with lighter elements such as S, N, and O in the form of oxides. Burning additives within lubricants are probable sources of Na, Ba, Ca, Zn, P and possibly Sn. Elements present and their percentages varied significantly across all engines, not revealing any trend or identifiable cause for the differences, though the origin is likely the same for the same element when observed. This finding suggests that their presence can be used as a tracer for identifying soots from aircraft engines as well as diagnostic for monitoring engine performance and wear.

Lightning-produced Carbon Species in the Atmosphere of Saturn

NASA Astrophysics Data System (ADS)

Delitsky, Mona; Baines, K. H.

2010-10-01

Recent studies by Baines et al (2009) indicate that thunderstorm-associated clouds on Saturn are spectrally dark from 0.7 to 4 um, darker than regular clouds. This darkening is found to be consistent with the presence of particles of elemental carbon, such as in the form of soot particles mixed in with spectrally bright condensates. This carbon is thought to be generated by lightning-induced dissociation of methane. Lightning on Saturn will input large amounts of energy to a narrow column of atmosphere and generate products at high energies such as radicals and ions. After the column cools down, the new chemical species recombine and are frozen into a new chemical equilibrium. Experimental studies in the literature of reactions of methane and other gases in plasma discharges (which simulate lightning) indicate that, even with high ratios of hydrogen/methane, the elemental carbon obtained will form solid dark particles that persist and have a very high C/H ratio. Basically, they are mostly pure carbon, in the form of soot, amorphous carbon, graphite, graphene, polycyclic aromatic hydrocarbons, carbon black, carbon onions, etc. Hydrogen will act as a sealant onto the particles and attach to dangling bonds on their growing surfaces. Even in experiments to form the most crystalline allotrope of carbon, that is, diamond, the presence of hydrogen does not inhibit diamond formation, even at the low pressures in the atmospheres of the Jovian planets or in the interstellar medium (Allamandola et al 1991). Therefore, some form of elemental carbon is likely produced in Saturnian storm clouds and may occur as dark particles of either amorphous carbon, PAHs or crystalline carbon in a form such as graphite. ..Refs: Baines et al., PSS 57, 1650-1658 (2009) ; Allamandola et al., Meteoritics 26, 313 (1991).

High-Resolution Autoradiography

NASA Technical Reports Server (NTRS)

Towe, George C; Gomberg, Henry J; Freemen, J W

1955-01-01

This investigation was made to adapt wet-process autoradiography to metallurgical samples to obtain high resolution of segregated radioactive elements in microstructures. Results are confined to development of the technique, which was perfected to a resolution of less than 10 microns. The radioactive samples included carbon-14 carburized iron and steel, nickel-63 electroplated samples, a powder product containing nickel-63, and tungsten-185 in N-155 alloy.

Optical properties of ZnO/BaCO3 nanocomposites in UV and visible regions.

PubMed

Zak, Ali Khorsand; Hashim, Abdul Manaf; Darroudi, Majid

2014-01-01

Pure zinc oxide and zinc oxide/barium carbonate nanoparticles (ZnO-NPs and ZB-NPs) were synthesized by the sol-gel method. The prepared powders were characterized by X-ray diffraction (XRD), ultraviolet-visible (UV-Vis), Auger spectroscopy, and transmission electron microscopy (TEM). The XRD result showed that the ZnO and BaCO3 nanocrystals grow independently. The Auger spectroscopy proved the existence of carbon in the composites besides the Zn, Ba, and O elements. The UV-Vis spectroscopy results showed that the absorption edge of ZnO nanoparticles is redshifted by adding barium carbonate. In addition, the optical parameters including the refractive index and permittivity of the prepared samples were calculated using the UV-Vis spectra. 81.05.Dz; 78.40.Tv; 42.70.-a.

The Quest for Organic Carbon on Mars

NASA Technical Reports Server (NTRS)

Eigenbrode, Jennifer

2011-01-01

We are entering an era of Mars exploration in which organic carbon detection, characterization, and structural identification will be key to addressing some of the outstanding science objectives of the Mars Exploration Program. Success of these missions will depend on technical, scientific, and strategic elements--all of which are strongly determined based on terrestrial experience and knowledge of organic matter formation, concentration, and preservation. Analog studies including Precambrian sediments, modern endolithic communities, and experiments help us fine-tune these approaches, but we also need to expect the unexpected. This presentation will provide perspective on the challenges of detecting organic carbon on Mars, how we may achieve such detections with the in situ instruments, such as the SAM (Science Analysis at Mars) instrument suite onboard Curiosity, the rover for the 2011 Mars Science Laboratory mission.

Iron and manganese in anaerobic respiration: environmental significance, physiology, and regulation

NASA Technical Reports Server (NTRS)

Nealson, K. H.; Saffarini, D.

1994-01-01

Dissimilatory iron and/or manganese reduction is known to occur in several organisms, including anaerobic sulfur-reducing organisms such as Geobacter metallireducens or Desulfuromonas acetoxidans, and facultative aerobes such as Shewanella putrefaciens. These bacteria couple both carbon oxidation and growth to the reduction of these metals, and inhibitor and competition experiments suggest that Mn(IV) and Fe(III) are efficient electron acceptors similar to nitrate in redox abilities and capable of out-competing electron acceptors of lower potential, such as sulfate (sulfate reduction) or CO2 (methanogenesis). Field studies of iron and/or manganese reduction suggest that organisms with such metabolic abilities play important roles in coupling the oxidation of organic carbon to metal reduction under anaerobic conditions. Because both iron and manganese oxides are solids or colloids, they tend to settle downward in aquatic environments, providing a physical mechanism for the movement of oxidizing potential into anoxic zones. The resulting biogeochemical metal cycles have a strong impact on many other elements including carbon, sulfur, phosphorous, and trace metals.

Measurement of soil carbon oxidation state and oxidative ratio by 13C nuclear magnetic resonance

USGS Publications Warehouse

Hockaday, W.C.; Masiello, C.A.; Randerson, J.T.; Smernik, R.J.; Baldock, J.A.; Chadwick, O.A.; Harden, J.W.

2009-01-01

The oxidative ratio (OR) of the net ecosystem carbon balance is the ratio of net O2 and CO2 fluxes resulting from photosynthesis, respiration, decomposition, and other lateral and vertical carbon flows. The OR of the terrestrial biosphere must be well characterized to accurately estimate the terrestrial CO2 sink using atmospheric measurements of changing O2 and CO2 levels. To estimate the OR of the terrestrial biosphere, measurements are needed of changes in the OR of aboveground and belowground carbon pools associated with decadal timescale disturbances (e.g., land use change and fire). The OR of aboveground pools can be measured using conventional approaches including elemental analysis. However, measuring the OR of soil carbon pools is technically challenging, and few soil OR data are available. In this paper we test three solid-state nuclear magnetic resonance (NMR) techniques for measuring soil OR, all based on measurements of the closely related parameter, organic carbon oxidation state (Cox). Two of the three techniques make use of a molecular mixing model which converts NMR spectra into concentrations of a standard suite of biological molecules of known C ox. The third technique assigns Cox values to each peak in the NMR spectrum. We assess error associated with each technique using pure chemical compounds and plant biomass standards whose Cox and OR values can be directly measured by elemental analyses. The most accurate technique, direct polarization solid-state 13C NMR with the molecular mixing model, agrees with elemental analyses to ??0.036 Cox units (??0.009 OR units). Using this technique, we show a large natural variability in soil Cox and OR values. Soil Cox values have a mean of -0.26 and a range from -0.45 to 0.30, corresponding to OR values of 1.08 ?? 0.06 and a range from 0.96 to 1.22. We also estimate the OR of the carbon flux from a boreal forest fire. Analysis of soils from nearby intact soil profiles imply that soil carbon losses associated with the fire had an OR of 1.091 (??0.003). Fire appears to be a major factor driving the soil C pool to higher oxidation states and lower OR values. Episodic fluxes caused by disturbances like fire may have substantially different ORs from ecosystem respiration fluxes and therefore should be better quantified to reduce uncertainties associated with our understanding of the global atmospheric carbon budget. Copyright 2009 by the American Geophysical Union.

Influence of oxygen on growth of carbon thin films

NASA Astrophysics Data System (ADS)

Kumar, Prabhat; Gupta, Mukul; Phase, D. M.; Stahn, Jochen

2018-04-01

In this work we studied the influence of oxygen gas on growth of carbon thin films in a magnetron sputtering process. X-ray absorption spectroscopy (XAS), x-ray and neutron reflectivity techniques were used to probe carbon thin films deposited with and without oxygen at room temperature. XAS in particularly x-ray absorption near edge spectroscopy (XANES) is powerful technique to identify the nature of hybridization of carbon atoms with other elements. In a XANES pattern, presence of C=O and C-O bonds is generally observed in spite of the fact that oxygen has not been deliberately included in the growth process. In order to confirm the presence of such features, we introduced a small amount of oxygen at 1% during the growth of carbon thin films. Though such additions do not affect the number density as observed by x-ray and neutron reflectivity, they severally affect the C K-edge spectra as evidenced by an enhancement in carbon-oxygen hybridization. Observed results are helpful in analyzing the C K-edge spectra more confidently.

Fine-Grained Turbidites: Facies, Attributes and Process Implications

NASA Astrophysics Data System (ADS)

Stow, Dorrik; Omoniyi, Bayonle

2016-04-01

Within turbidite systems, fine-grained sediments are still the poor relation and sport several contrasting facies models linked to process of deposition. These are volumetrically the dominant facies in deepwater and, from a resource perspective, they form important marginal and tight reservoirs, and have great potential for unconventional shale gas, source rocks and seals. They are also significant hosts of metals and rare earth elements. Based on a large number of studies of modern, ancient and subsurface systems, including 1000s of metres of section logging, we define the principal genetic elements of fine-grained deepwater facies, present a new synthesis of facies models and their sedimentary attributes. The principal architectural elements include: non-channelised slope-aprons, channel-fill, channel levee and overbank, turbidite lobes, mass-transport deposits, contourite drifts, basin sheets and drapes. These comprise a variable intercalation of fine-grained facies - thin-bedded and very thin-bedded turbidites, contourites, hemipelagites and pelagites - and associated coarse-grained facies. Characteristic attributes used to discriminate between these different elements are: facies and facies associations; sand-shale ratio, sand and shale geometry and dimensions, sand connectivity; sediment texture and small-scale sedimentary structures; sediment fabric and microfabric; and small-scale vertical sequences of bed thickness. To some extent, we can relate facies and attribute characteristics to different depositional environments. We identify four distinct facies models: (a) silt-laminated mud turbidites, (b) siliciclastic mud turbidites, (c) carbonate mud turbidites, (d) disorganized silty-mud turbidites, and (e) hemiturbidites. Within the grainsize-velocity matrix turbidite plot, these all fall within the region of mean size < 0.063mm, maximum grainsize (one percentile) <0.2mm, and depositional velocity 0.1-0.5 m/s. Silt-laminated turbidites and many mud turbidites reflect uniform, steady flow characteristics and a depositional sorting mechanism for silt-clay separation; whereas disorganized turbidites reflect an unsteady flow type, either as a short-lived surge or as a mud-contaminated mid-flow. Fine-grained carbonate turbidites show certain distinctive characteristics linked to the different dynamic behaviour of fine carbonate material. Hemiturbidites are the result of long-distance transport and an upward buoyancy mechanism during deposition.

Health effects of carbon-containing particulate matter: focus on sources and recent research program results.

PubMed

Rohr, Annette; McDonald, Jacob

2016-02-01

Air pollution is a complex mixture of gas-, vapor-, and particulate-phase materials comprised of inorganic and organic species. Many of these components have been associated with adverse health effects in epidemiological and toxicological studies, including a broad spectrum of carbonaceous atmospheric components. This paper reviews recent literature on the health impacts of organic aerosols, with a focus on specific sources of organic material; it is not intended to be a comprehensive review of all the available literature. Specific emission sources reviewed include engine emissions, wood/biomass combustion emissions, biogenic emissions and secondary organic aerosol (SOA), resuspended road dust, tire and brake wear, and cooking emissions. In addition, recent findings from large toxicological and epidemiological research programs are reviewed in the context of organic PM, including SPHERES, NPACT, NERC, ACES, and TERESA. A review of the extant literature suggests that there are clear health impacts from emissions containing carbon-containing PM, but difficulty remains in apportioning responses to certain groupings of carbonaceous materials, such as organic and elemental carbon, condensed and gas phases, and primary and secondary material. More focused epidemiological and toxicological studies, including increased characterization of organic materials, would increase understanding of this issue.

Reviews and syntheses: Revisiting the boron systematics of aragonite and their application to coral calcification

NASA Astrophysics Data System (ADS)

DeCarlo, Thomas M.; Holcomb, Michael; McCulloch, Malcolm T.

2018-05-01

The isotopic and elemental systematics of boron in aragonitic coral skeletons have recently been developed as a proxy for the carbonate chemistry of the coral extracellular calcifying fluid. With knowledge of the boron isotopic fractionation in seawater and the B/Ca partition coefficient (KD) between aragonite and seawater, measurements of coral skeleton δ11B and B/Ca can potentially constrain the full carbonate system. Two sets of abiogenic aragonite precipitation experiments designed to quantify KD have recently made possible the application of this proxy system. However, while different KD formulations have been proposed, there has not yet been a comprehensive analysis that considers both experimental datasets and explores the implications for interpreting coral skeletons. Here, we evaluate four potential KD formulations: three previously presented in the literature and one newly developed. We assess how well each formulation reconstructs the known fluid carbonate chemistry from the abiogenic experiments, and we evaluate the implications for deriving the carbonate chemistry of coral calcifying fluid. Three of the KD formulations performed similarly when applied to abiogenic aragonites precipitated from seawater and to coral skeletons. Critically, we find that some uncertainty remains in understanding the mechanism of boron elemental partitioning between aragonite and seawater, and addressing this question should be a target of additional abiogenic precipitation experiments. Despite this, boron systematics can already be applied to quantify the coral calcifying fluid carbonate system, although uncertainties associated with the proxy system should be carefully considered for each application. Finally, we present a user-friendly computer code that calculates coral calcifying fluid carbonate chemistry, including propagation of uncertainties, given inputs of boron systematics measured in coral skeleton.

Mining Genomes of Marine Cyanobacteria for Elements of Zinc Homeostasis

PubMed Central

Barnett, James P.; Millard, Andrew; Ksibe, Amira Z.; Scanlan, David J.; Schmid, Ralf; Blindauer, Claudia Andrea

2012-01-01

Zinc is a recognized essential element for the majority of organisms, and is indispensable for the correct function of hundreds of enzymes and thousands of regulatory proteins. In aquatic photoautotrophs including cyanobacteria, zinc is thought to be required for carbonic anhydrase and alkaline phosphatase, although there is evidence that at least some carbonic anhydrases can be cambialistic, i.e., are able to acquire in vivo and function with different metal cofactors such as Co2+ and Cd2+. Given the global importance of marine phytoplankton, zinc availability in the oceans is likely to have an impact on both carbon and phosphorus cycles. Zinc concentrations in seawater vary over several orders of magnitude, and in the open oceans adopt a nutrient-like profile. Most studies on zinc handling by cyanobacteria have focused on freshwater strains and zinc toxicity; much less information is available on marine strains and zinc limitation. Several systems for zinc homeostasis have been characterized in the freshwater species Synechococcus sp. PCC 7942 and Synechocystis sp. PCC 6803, but little is known about zinc requirements or zinc handling by marine species. Comparative metallo-genomics has begun to explore not only the putative zinc proteome, but also specific protein families predicted to have an involvement in zinc homeostasis, including sensors for excess and limitation (SmtB and its homologs as well as Zur), uptake systems (ZnuABC), putative intracellular zinc chaperones (COG0523) and metallothioneins (BmtA), and efflux pumps (ZiaA and its homologs). PMID:22514551

A SURVEY OF THE CORROSION OF MARTENSITIC AND FERRITIC STAINLESS STEELS IN PRESSURIZED WATER

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

Beaver, R.J.; Leitten, C.F. Jr.

1963-07-16

>The corrosion resistance of mantensitic and ferritic austenitic stainless steels and carbon steels in pressurized water at 500 to 600 deg F is compared. Included are specific out-of-pile data for austenitic stainless steels, AISI types types 410, 420, 431, and 440C; the ferritic AISI types 430, 442, and 446; the precipitation-hardening type 17-4PH; and carbon steels, ASTM 212 A and B. Available corrosion results obtained under irradiation at exposures in the range of 7 x 10/sup 16/ to 3 x 10/sup 19/ nvt are also included for types 304, types of martensitic and ferritic stainless steels which were evaluated domore » not contain nickel. For application where it is desirable to minimize Co/sup 58/ activity produced from nickel, selection of a martensitic or ferritic stainless steel may be more appropriate than choosing the more popular nickel-bearing austenitic stainless steel or a fuel-element cladding material. Interpretation of the data indicates that, on the average, martensitic and ferritic stainless steels corrode more rapidly than austenitic alloys but more slowly than carbon and low-alloy steels. Under selected controlled water conditions or under irradiation, the corrosion of the nickel-free stainless steels appears to differ little from the austenitics. The corrosion of martensitic and ferritic stainless steels in pressurized-water systems therefore does not appear of such magnitude as to rule out development of these materials as the cladding fuel elements for specific applications. (auth)« less

Modelling of single walled carbon nanotube cylindrical structures with finite element method simulations

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

Günay, E.

In this study, the modulus of elasticity and shear modulus values of single-walled carbon nanotubes SWCNTs were modelled by using both finite element method and the Matlab code. Initially, cylindrical armchair and zigzag single walled 3D space frames were demonstrated as carbon nanostructures. Thereafter, macro programs were written by the Matlab code producing the space truss for zigzag and armchair models. 3D space frames were introduced to the ANSYS software and then tension, compression and additionally torsion tests were performed on zigzag and armchair carbon nanotubes with BEAM4 element in obtaining the exact values of elastic and shear modulus values.more » In this study, two different boundary conditions were tested and especially used in torsion loading. The equivalent shear modulus data was found by averaging the corresponding values obtained from ten different nodal points on the nanotube path. Finally, in this study it was determined that the elastic constant values showed proportional changes by increasing the carbon nanotube diameters up to a certain level but beyond this level these values remained stable.« less

ENTRAINED-FLOW ADSORPTION OF MERCURY USING ACTIVATED CARBON

EPA Science Inventory

Bench-scale experiments were conducted in a flow reactor to simulate entrained-flow capture of elemental mercury (Hg) by activated carbon. Adsorption of Hg by several commercial activated carbons was examined at different carbon-to-mercury (C:Hg) ratios (by weight) (600:1 - 29000...

Organic Elemental Analysis.

ERIC Educational Resources Information Center

Ma, T. S.; Gutterson, Milton

1980-01-01

Reviews general developments in computerization and data processing of organic elemental analyses; carbon, hydrogen, and nitrogen analyzers; procedures for determining oxygen, sulfur, and halogens, as well as other nometallic elements and organometallics. Selected papers on trace analysis of nonmetals and determination of metallic elements are…

Comprehensive characterisation of atmospheric aerosols in Budapest, Hungary: physicochemical properties of inorganic species

NASA Astrophysics Data System (ADS)

Salma, Imre; Maenhaut, Willy; Zemplén-Papp, Éva; Záray, Gyula

As part of an air pollution project in Budapest, aerosol samples were collected by stacked filter units and cascade impactors at an urban background site, two downtown sites, and within a road tunnel in field campaigns conducted in 1996, 1998 and 1999. Some criteria pollutants were also measured at one of the downtown sites. The aerosol samples were analysed by one or more of the following methods: instrumental neutron activation analysis, particle-induced X-ray emission analysis, a light reflection technique, gravimetry, thermal profiling carbon analysis and capillary electrophoresis. The quantities measured or derived include atmospheric concentrations of elements (from Na to U), of particulate matter, of black and elemental carbon, and total carbonaceous fraction, of some ionic species (e.g., nitrate and sulphate) in the fine ( <2 μm equivalent aerodynamic diameter, EAD) or in both coarse (10- 2 μm EAD) and fine size fractions, atmospheric concentrations of NO, NO 2, SO 2, CO and total suspended particulate matter, and meteorological parameters. The analytical results were used for characterisation of the concentration levels, elemental composition, time trends, enrichment of and relationships among the aerosol species in coarse and fine size fractions, for studying their fine-to-coarse concentration ratios, spatial and temporal variability, for determining detailed elemental mass size distributions, and for examining the extent of chemical mass closure.

Photographic Combustion Characterization of LOX/Hydrocarbon Type Propellants

NASA Technical Reports Server (NTRS)

Judd, D. C.

1980-01-01

The advantages and limitations of using high speed photography to identify potential combustion anomalies (pops, fuel freezing, reactive stream separation (RSS), carbon formation) were demonstrated. Combustion evaluation criteria were developed for evaluating, characterizing, and screening promising low cost propellant combination(s) and injector element(s) for long life, reusable engine systems. Carbon formation and RSS mechanisms and trends were identified by using high speed color photography at speeds up to 6000 frames/sec. Single element injectors were tested with LOX/RP-1, LOX/Propane, LOX/Methane and LOX/Ammonia propellants. Tests were conducted using seven separate injector elements. Five different conventionally machined elements were tested: OFO Triplet; Rectangular Unlike Doublet (RUD); Unlike Doublet (UD); Like on Lke Doublet (LOL-EDM); and Slit Triplet.

Integrated in-situ probes for structural and dynamic properties of geological materials at ultrahigh pressures and temperatures

NASA Astrophysics Data System (ADS)

Mao, H.; Mao, W. L.

2005-12-01

Multiple x-ray and allied probes have been recently developed and integrated with diamond-anvil cells at synchrotron facilities. They have effectively opened up the vast field area of the Earth's interior to direct, in-situ study. For instance, x-ray emission spectroscopy identifies the high-spin-low-spin transition that governs Fe-Mg partitioning, the most important factor in element differentiation in the mantle. Inelastic x-ray near-edge spectroscopy reveals the bonding nature of light elements that control the phase transitions, structure and partitioning of these elements (e.g., carbon bonding changes as an element, and in oxides, carbonates, and silicates). X-ray diffraction combined with laser-heated diamond anvil cell determines crystal structures and P-V-T equations of state. Shear moduli, single-crystal elasticity, and phonon dynamics can be measured to the core pressures with newly-enabled, complementary techniques, including radial x-ray diffraction, nuclear resonant inelastic x-ray scattering, non-resonant inelastic x-ray scattering, high-temperature Raman spectroscopy, and Brillouin scattering spectroscopy. The nonhydrostatic stress in solid samples which was previously regarded as a nuisance that degraded the experiments, can now be used for extracting important rheological information, including deformation mechanisms, preferred orientation, slip systems, plasticity, failure, and shear strength of major mantle and core minerals at high pressures. With the new arsenal of experimental techniques over the extended P-T-x regimes at we can now address questions that were not conceivable only a decade ago. Knowledge of the high P-T properties is leading to fundamental improvements in interpreting seismological observations and understanding the structure, dynamics, and evolution of the Earth's deep interior.

Geochemical evidence for African dust and volcanic ash inputs to terra rossa soils on carbonate reef terraces, northern Jamaica, West Indies

USGS Publications Warehouse

Muhs, D.R.; Budahn, J.R.

2009-01-01

The origin of red or reddish-brown, clay-rich, "terra rossa" soils on limestone has been debated for decades. A traditional qualitative explanation for their formation has been the accumulation of insoluble residues as the limestone is progressively dissolved over time. However, this mode of formation often requires unrealistic or impossible amounts of carbonate dissolution. Therefore, where this mechanism is not viable and where local fluvial or colluvial inputs can be ruled out, an external source or sources must be involved in soil formation. On the north coast of the Caribbean island of Jamaica, we studied a sequence of terra rossa soils developed on emergent limestones thought to be of Quaternary age. The soils become progressively thicker, redder, more Fe- and Al-rich and Si-poor with elevation. Furthermore, although kaolinite is found in all the soils, the highest and oldest soils also contain boehmite. Major and trace element geochemistry shows that the host limestones and local igneous rocks are not likely source materials for the soils. Other trace elements, including the rare earth elements (REE), show that tephra from Central American volcanoes is not a likely source either. However, trace element geochemistry shows that airborne dust from Africa plus tephra from the Lesser Antilles island arc are possible source materials for the clay-rich soils. A third, as yet unidentified, source may also contribute to the soils. We hypothesize that older, more chemically mature Jamaican bauxites may have had a similar origin. The results add to the growing body of evidence of the importance of multiple parent materials, including far-traveled dust, to soil genesis.

The stable isotope composition of nitrogen and carbon and elemental contents in modern and fossil seabird guano from Northern Chile - Marine sources and diagenetic effects.

PubMed

Lucassen, Friedrich; Pritzkow, Wolfgang; Rosner, Martin; Sepúlveda, Fernando; Vásquez, Paulina; Wilke, Hans; Kasemann, Simone A

2017-01-01

Seabird excrements (guano) have been preserved in the arid climate of Northern Chile since at least the Pliocene. The deposits of marine organic material in coastal areas potentially open a window into the present and past composition of the coastal ocean and its food web. We use the stable isotope composition of nitrogen and carbon as well as element contents to compare the principal prey of the birds, the Peruvian anchovy, with the composition of modern guano. We also investigate the impact of diagenetic changes on the isotopic composition and elemental contents of the pure ornithogenic sediments, starting with modern stratified deposits and extending to fossil guano. Where possible, 14C systematics is used for age information. The nitrogen and carbon isotopic composition of the marine prey (Peruvian anchovy) of the birds is complex as it shows strong systematic variations with latitude. The detailed study of a modern profile that represents a few years of guano deposition up to present reveals systematic changes in nitrogen and carbon isotopic composition towards heavier values that increase with age, i.e. depth. Only the uppermost, youngest layers of modern guano show compositional affinity to the prey of the birds. In the profile, the simultaneous loss of nitrogen and carbon occurs by degassing, and non-volatile elements like phosphorous and calcium are passively enriched in the residual guano. Fossil guano deposits are very low in nitrogen and low in carbon contents, and show very heavy nitrogen isotopic compositions. One result of the study is that the use of guano for tracing nitrogen and carbon isotopic and elemental composition in the marine food web of the birds is restricted to fresh material. Despite systematic changes during diagenesis, there is little promise to retrieve reliable values of marine nitrogen and carbon signatures from older guano. However, the changes in isotopic composition from primary marine nitrogen isotopic signatures towards very heavy values generate a compositionally unique material. These compositions trace the presence of guano in natural ecosystems and its use as fertilizer in present and past agriculture.

The stable isotope composition of nitrogen and carbon and elemental contents in modern and fossil seabird guano from Northern Chile – Marine sources and diagenetic effects

PubMed Central

Pritzkow, Wolfgang; Rosner, Martin; Sepúlveda, Fernando; Vásquez, Paulina; Wilke, Hans; Kasemann, Simone A.

2017-01-01

Seabird excrements (guano) have been preserved in the arid climate of Northern Chile since at least the Pliocene. The deposits of marine organic material in coastal areas potentially open a window into the present and past composition of the coastal ocean and its food web. We use the stable isotope composition of nitrogen and carbon as well as element contents to compare the principal prey of the birds, the Peruvian anchovy, with the composition of modern guano. We also investigate the impact of diagenetic changes on the isotopic composition and elemental contents of the pure ornithogenic sediments, starting with modern stratified deposits and extending to fossil guano. Where possible, 14C systematics is used for age information. The nitrogen and carbon isotopic composition of the marine prey (Peruvian anchovy) of the birds is complex as it shows strong systematic variations with latitude. The detailed study of a modern profile that represents a few years of guano deposition up to present reveals systematic changes in nitrogen and carbon isotopic composition towards heavier values that increase with age, i.e. depth. Only the uppermost, youngest layers of modern guano show compositional affinity to the prey of the birds. In the profile, the simultaneous loss of nitrogen and carbon occurs by degassing, and non-volatile elements like phosphorous and calcium are passively enriched in the residual guano. Fossil guano deposits are very low in nitrogen and low in carbon contents, and show very heavy nitrogen isotopic compositions. One result of the study is that the use of guano for tracing nitrogen and carbon isotopic and elemental composition in the marine food web of the birds is restricted to fresh material. Despite systematic changes during diagenesis, there is little promise to retrieve reliable values of marine nitrogen and carbon signatures from older guano. However, the changes in isotopic composition from primary marine nitrogen isotopic signatures towards very heavy values generate a compositionally unique material. These compositions trace the presence of guano in natural ecosystems and its use as fertilizer in present and past agriculture. PMID:28594902

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.

Recovery of fissile materials from nuclear wastes

DOEpatents

Forsberg, Charles W.

1999-01-01

A process for recovering fissile materials such as uranium, and plutonium, and rare earth elements, from complex waste feed material, and converting the remaining wastes into a waste glass suitable for storage or disposal. The waste feed is mixed with a dissolution glass formed of lead oxide and boron oxide resulting in oxidation, dehalogenation, and dissolution of metal oxides. Carbon is added to remove lead oxide, and a boron oxide fusion melt is produced. The fusion melt is essentially devoid of organic materials and halogens, and is easily and rapidly dissolved in nitric acid. After dissolution, uranium, plutonium and rare earth elements are separated from the acid and recovered by processes such as PUREX or ion exchange. The remaining acid waste stream is vitrified to produce a waste glass suitable for storage or disposal. Potential waste feed materials include plutonium scrap and residue, miscellaneous spent nuclear fuel, and uranium fissile wastes. The initial feed materials may contain mixtures of metals, ceramics, amorphous solids, halides, organic material and other carbon-containing material.

A Fe-C-Ca big cycle in modern carbon-intensive industries: toward emission reduction and resource utilization

PubMed Central

Sun, Yongqi; Sridhar, Seetharaman; Seetharaman, Seshadri; Wang, Hao; Liu, Lili; Wang, Xidong; Zhang, Zuotai

2016-01-01

Herein a big Fe-C-Ca cycle, clarifying the basic element flows and energy flows in modern carbon-intensive industries including the metallurgical industry and the cement industry, was proposed for the first time in the contexts of emission reduction and iron ore degradation nowadays. This big cycle was focused on three industrial elements of Fe, C and Ca and thus it mainly comprised three interdependent loops, i.e., a C-cycle, a Fe-cycle and a Ca-path. As exemplified, we started from the integrated disposal of hot steel slags, a man-made iron resource via char gasification and the employment of hematite, a natural iron resource greatly extended the application area of this idea. Accordingly, based on this concept, the theoretical potentials for energy saving, emission reduction and Fe resource recovery achieved in modern industry are estimated up to 7.66 Mt of standard coal, 63.9 Mt of CO2 and 25.2 Mt of pig iron, respectively. PMID:26923104

A Fe-C-Ca big cycle in modern carbon-intensive industries: toward emission reduction and resource utilization

NASA Astrophysics Data System (ADS)

Sun, Yongqi; Sridhar, Seetharaman; Seetharaman, Seshadri; Wang, Hao; Liu, Lili; Wang, Xidong; Zhang, Zuotai

2016-02-01

Herein a big Fe-C-Ca cycle, clarifying the basic element flows and energy flows in modern carbon-intensive industries including the metallurgical industry and the cement industry, was proposed for the first time in the contexts of emission reduction and iron ore degradation nowadays. This big cycle was focused on three industrial elements of Fe, C and Ca and thus it mainly comprised three interdependent loops, i.e., a C-cycle, a Fe-cycle and a Ca-path. As exemplified, we started from the integrated disposal of hot steel slags, a man-made iron resource via char gasification and the employment of hematite, a natural iron resource greatly extended the application area of this idea. Accordingly, based on this concept, the theoretical potentials for energy saving, emission reduction and Fe resource recovery achieved in modern industry are estimated up to 7.66 Mt of standard coal, 63.9 Mt of CO2 and 25.2 Mt of pig iron, respectively.

Tracing the source of sedimentary organic carbon in the Loess Plateau of China: An integrated elemental ratio, stable carbon signatures, and radioactive isotopes approach.

PubMed

Liu, Chun; Dong, Yuting; Li, Zhongwu; Chang, Xiaofeng; Nie, Xiaodong; Liu, Lin; Xiao, Haibing; Bashir, Hassan

2017-02-01

Soil erosion, which will induce the redistribution of soil and associated soil organic carbon (SOC) on the Earth's surface, is of critically importance for biogeochemical cycling of essential elements and terrestrial carbon sequestration. Despite the importance of soil erosion, surprisingly few studies have evaluated the sources of eroded carbon (C). This study used natural abundance levels of the stable isotope signature ( 13 C) and radioactive isotopes ( 137 Cs and 210 Pb ex ), along with elements ratio (C/N) based on a two end member mixing model to qualitatively and quantitatively identify the sources of sedimentary OC retained by check dam in the Qiaozigou small watershed in the Loess Plateau, China. Sediment profiles (0-200 cm) captured at natural depositional area of the basin was compared to possible source materials, which included: superficial Loess mineral soils (0-20 cm) from three land use types [i.e., grassland (Medicago sativa), forestland (Robinia pseudoacacia.), shrubland (Prunus sibirica), and gully land (Loess parent material.)]. The results demonstrated that SOC in sediments showed significantly negative correlation with pH (P < 0.01), and positive correlation with soil water content (SWC) (P < 0.05). The sedimentary OC was not derived from grasslands or gullies. Forestland and shrubland were two main sources of eroded organic carbon within the surface sediment (0-60 cm deep), except for that in the 20-40 cm soil layer. Radionuclides analyses also implied that the surface sediments retained by check-dams mainly originated from soils of forestland and shrubland. Results of the two end-member mixing model demonstrated that more than 50% SOC (mean probability estimate (MPE) 50.13% via 13 C and 60.53% via C/N) in surface sediment (0-20 cm deep) derived from forestland, whereas subsurface sedimentary SOC (20-200 cm) mainly resulted from shrubland (MPE > 50%). Although uncertainties on the sources of SOC in deep soils exist, the soil organic δ 13 C and C/N is still an effective indicator for sources of sedimentary organic carbon in the deposition zone in the short term (<10 years). Copyright © 2016 Elsevier Ltd. All rights reserved.

Neoproterozoic marine carbonates and their paleoceanographic significance

NASA Astrophysics Data System (ADS)

Hood, Ashleigh van Smeerdijk; Wallace, Malcolm William

2018-01-01

The primary mineralogy of marine carbonate precipitates has been a crucial factor in constraining the major element composition of ancient oceans. Secular changes in Phanerozoic marine chemistry, including Mg/Ca, have been well-documented using the original carbonate mineralogy of ooids, marine cements and biominerals. However, the history of Precambrian seawater chemistry is not as well constrained, partially due to the prevalence of dolomitisation in the Precambrian geological record. The Neoproterozoic ( 1000 Ma to 541 Ma) record of primary carbonate mineralogy is documented here using a combination of literature data and new analysis of marine carbonate precipitates from the Otavi Fold Belt, Namibia, the Death Valley succession, USA and the Adelaide Fold Belt, Australia. These data suggest that the last 460 million years of the Proterozoic were dominated by aragonite and high-Mg calcite precipitation in shallow marine settings. In contrast, low-Mg calcite has only been recognised in a small number of formations. In addition to aragonite and calcite precipitation, marine dolomite precipitation was widespread in Neoproterozoic oceans, including mimetic (syn-sedimentary) dolomitisation and primary dolomite marine cementation. The combination of marine aragonite, high Mg-calcite and dolomite precipitation during the Neoproterozoic suggests extremely high seawater Mg/Ca conditions relative to Phanerozoic oceans. Marine dolomite precipitation may also be linked to widespread marine anoxia during this time.

Large-Scale Fabrication of Carbon Nanotube Probe Tips For Atomic Force Microscopy Critical Dimension Imaging Applications

NASA Technical Reports Server (NTRS)

Ye, Qi Laura; Cassell, Alan M.; Stevens, Ramsey M.; Meyyappan, Meyya; Li, Jun; Han, Jie; Liu, Hongbing; Chao, Gordon

2004-01-01

Carbon nanotube (CNT) probe tips for atomic force microscopy (AFM) offer several advantages over Si/Si3N4 probe tips, including improved resolution, shape, and mechanical properties. This viewgraph presentation discusses these advantages, and the drawbacks of existing methods for fabricating CNT probe tips for AFM. The presentation introduces a bottom up wafer scale fabrication method for CNT probe tips which integrates catalyst nanopatterning and nanomaterials synthesis with traditional silicon cantilever microfabrication technology. This method makes mass production of CNT AFM probe tips feasible, and can be applied to the fabrication of other nanodevices with CNT elements.

Whole Watershed Quantification of Net Carbon Fluxes by Erosion and Deposition within the Christina River Basin Critical Zone Observatory

NASA Astrophysics Data System (ADS)

Aufdenkampe, A. K.; Karwan, D. L.; Aalto, R. E.; Marquard, J.; Yoo, K.; Wenell, B.; Chen, C.

2013-12-01

We have proposed that the rate at which fresh, carbon-free minerals are delivered to and mix with fresh organic matter determines the rate of carbon preservation at a watershed scale (Aufdenkampe et al. 2011). Although many studies have examined the role of erosion in carbon balances, none consider that fresh carbon and fresh minerals interact. We believe that this mechanism may be a dominant sequestration process in watersheds with strong anthropogenic impacts. Our hypothesis - that the rate of mixing fresh carbon with fresh, carbon-free minerals is a primary control on watershed-scale carbon sequestration - is central to our Christina River Basin Critical Zone Observatory project (CRB-CZO, http://www.udel.edu/czo/). The Christina River Basin spans 1440 km2 from piedmont to Atlantic coastal plain physiographic provinces in the states of Pennsylvania and Delaware, and experienced intensive deforestation and land use beginning in the colonial period of the USA. Here we present a synthesis of multi-disciplinary data from the CRB-CZO on materials as they are transported from sapprolite to topsoils to colluvium to suspended solids to floodplains, wetlands and eventually to the Delaware Bay estuary. At the heart of our analysis is a spatially-integrated, flux-weighted comparison of the organic carbon to mineral surface area ratio (OC/SA) of erosion source materials versus transported and deposited materials. Because source end-members - such as forest topsoils, farmed topsoils, gullied subsoils and stream banks - represent a wide distribution of initial, pre-erosion OC/SA, we quantify source contributions using geochemical sediment fingerprinting approaches (Walling 2005). Analytes used for sediment fingerprinting include: total mineral elemental composition (including rare earth elements), fallout radioisotope activity for common erosion tracers (beryllium-7, beryllium-10, lead-210, cesium-137), particle size distribution and mineral specific surface area, in addition to organic carbon and nitrogen content with stable isotope (13C, 15N) and radiocarbon (14C) abundance to quantify OC/SA and organic carbon sources and mean age. We then use multivariate mixing model analysis to quantify the fractional contribution of each source end-member to each sample of suspended or deposited sediments. Last, we calculate a predicted OC/SA based on source end-member mixing and compare to the measured OC/SA to quantify net change in mineral complexed carbon. Aufdenkampe, A.K. et al. Riverine coupling of biogeochemical cycles between land, oceans, and atmosphere. Frontiers Ecol. Environ. 9, 53-60 (2011). Walling, D. E. Tracing suspended sediment sources in catchments and river systems. Sci. Total Environ. 34, 159-184 (2005).

ELEMENTAL MERCURY ADSORPTION BY ACTIVATED CARBON TREATED WITH SULFURIC ACID

EPA Science Inventory

The paper gives results of a study of the adsorption of elemental mercury at 125 C by a sulfuric-acid (H2S04, 50% w/w/ solution)-treated carbon for the removal of mercury from flue gas. The pore structure of the sample was characterized by nitrogen (N2) at -196 C and the t-plot m...

Structural Analysis of a Carbon Nitride Film Prepared by Ion-Beam-Assisted Deposition

NASA Astrophysics Data System (ADS)

Hayashi, Toshiyuki; Matsumuro, Akihito; Muramatsu, Mutsuo; Kohzaki, Masao; Takahashi, Yutaka; Yamaguchi, Katsumi

1999-04-01

The microstructure of a carbon nitride (CNx) film formed by ion-beam-assisted deposition (IBAD) was investigated by transmission electron microscopy (TEM). This film was formed on the Si (100) substrate by IBAD with an N/C transport ratio of 1. Three different spacings (0.34 nm, 0.21 nm, 0.12 nm) were observed by transmission electron diffraction (TED) and the periodic structure corresponding to the spacing of 0.34 nm was aligned perpendicular to the substrate. The bending of this plane resembled a carbon nanotube; therefore, it seemed reasonable to suppose that the CNx film obtained consisted of numerous carbon-nanotube-like structural elements grown vertically, relative to the substrate, and it also seemed appropriate that these structural elements should be termed nanotube-like carbon nitride.

The role of liquid-liquid immiscibility and crystal fractionation in the genesis of carbonatite magmas: insights from Kerimasi melt inclusions

NASA Astrophysics Data System (ADS)

Guzmics, Tibor; Zajacz, Zoltán; Mitchell, Roger H.; Szabó, Csaba; Wälle, Markus

2015-02-01

We have reconstructed the compositional evolution of the silicate and carbonate melt, and various crystalline phases in the subvolcanic reservoir of Kerimasi Volcano in the East African Rift. Trace element concentrations of silicate and carbonate melt inclusions trapped in nepheline, apatite and magnetite from plutonic afrikandite (clinopyroxene-nepheline-perovskite-magnetite-melilite rock) and calciocarbonatite (calcite-apatite-magnetite-perovskite-monticellite-phlogopite rock) show that liquid immiscibility occurred during the generation of carbonatite magmas from a CO2-rich melilite-nephelinite magma formed at relatively high temperatures (1,100 °C). This carbonatite magma is notably more calcic and less alkaline than that occurring at Oldoinyo Lengai. The CaO-rich (32-41 wt%) nature and alkali-"poor" (at least 7-10 wt% Na2O + K2O) nature of these high-temperature (>1,000 °C) carbonate melts result from strong partitioning of Ca (relative to Mg, Fe and Mn) in the immiscible carbonate and the CaO-rich nature (12-17 wt%) of its silicate parent (e.g., melilite-nephelinite). Evolution of the Kerimasi carbonate magma can result in the formation of natrocarbonatite melts with similar composition to those of Oldoinyo Lengai, but with pronounced depletion in REE and HFSE elements. We suggest that this compositional difference results from the different initial parental magmas, e.g., melilite-nephelinite at Kerimasi and a nephelinite at Oldoinyo Lengai. The difference in parental magma composition led to a significant difference in the fractionating mineral phase assemblage and the element partitioning systematics upon silicate-carbonate melt immiscibility. LA-ICP-MS analysis of coeval silicate and carbonate melt inclusions provides an opportunity to infer carbonate melt/silicate melt partition coefficients for a wide range of elements. These data show that Li, Na, Pb, Ca, Sr, Ba, B, all REE (except Sc), U, V, Nb, Ta, P, Mo, W and S are partitioned into the carbonate melt, whereas Mg, Mn, Fe, Co, Cu, Zn, Al, Sc, Ti, Hf and Zr are partitioned into the silicate melt. Potassium and Rb show no preferential partitioning. Kerimasi melt inclusions show that the immiscible calcic carbonate melt is strongly enriched in Sr, Ba, Pb, LREE, P, W, Mo and S relative to other trace elements. Comparison of our data with experimental results indicates that preferential partitioning of oxidized sulfur (as SO4 2-), Ca and P (as PO4 3-) into the carbonate melt may promote the partitioning of Nb, Ta, Pb and all REE, excluding Sc, into this phase. Therefore, it is suggested that P and S enrichment in calcic carbonate magmas promotes the genesis of REE-rich carbonatites by liquid immiscibility. Our study shows that changes in the partition coefficients of elements between minerals and the coexisting melts along the liquid line of descent are rather significant at Kerimasi. This is why, in addition to the REE, Nb, Ta and Zr are also enriched in Kerimasi calciocarbonatites. We consider significant amounts of apatite and perovskite precipitated from melilite-nephelinite-derived carbonate melt as igneous minerals can have high LREE, Nb and Zr contents relative to other carbonatite minerals.

Diagnostic Evaluation of Carbon Sources in CMAQ

EPA Science Inventory

Traditional monitoring networks measure only total elemental carbon (EC) and organic carbon (OC) routinely. Diagnosing model biases with such limited information is difficult. Measurements of organic tracer compounds have recently become available and allow for more detailed di...

Partitioning of Nb, Mo, Ba, Ce, Pb, Th and U between immiscible carbonate and silicate liquids: Evaluating the effects of P2O5,F, and carbonate composition

NASA Technical Reports Server (NTRS)

Jones, J. H.; Walker, D.

1993-01-01

Previously we have reported carbonate liq./silicate liq. partition coefficients (D) for a standard suite of trace elements (Nb, Mo, Ba, Ce, Pb, Th, and U) and Ra and Pa as well. In brief, we have found that immiscible liquid partitioning is a strong function of temperature. As the critical temperature of the carbonate-silicate solvus is approached, all partition coefficients approach unity. Additionally, for the overwhelming majority of the partitioning elements, InD is a linear function of 'ionic field strength,' z/r, where z is the charge of the partitioned cation and r is its ionic radius.

Effects of carbon fiber surface characteristics on interfacial bonding of epoxy resin composite subjected to hygrothermal treatments

NASA Astrophysics Data System (ADS)

Li, Min; Liu, Hongxin; Gu, Yizhuo; Li, Yanxia; Zhang, Zuoguang

2014-01-01

The changes of interfacial bonding of three types of carbon fibers/epoxy resin composite as well as their corresponding desized carbon fiber composites subjecting to hygrothermal conditions were investigated by means of single fiber fragmentation test. The interfacial fracture energy was obtained to evaluate the interfacial bonding before and after boiling water aging. The surface characteristics of the studied carbon fiber were characterized using X-ray photoelectron spectroscopy. The effects of activated carbon atoms and silicon element at carbon fiber surface on the interfacial hygrothermal resistance were further discussed. The results show that the three carbon fiber composites with the same resin matrix possess different hygrothermal resistances of interface and the interfacial fracture energy after water aging can not recovery to the level of raw dry sample (irreversible changes) for the carbon fiber composites containing silicon. Furthermore, the activated carbon atoms have little impact on the interfacial hygrothermal resistance. The irreversible variations of interfacial bonding and the differences among different carbon fiber composites are attributed to the silicon element on the carbon fiber bodies, which might result in hydrolyzation in boiling water treatment and degrade interfacial hygrothermal resistance.

Phloem transport in gymnosperms: a question of pressure and resistance.

PubMed

Liesche, Johannes; Schulz, Alexander

2018-01-04

Even in the highest trees, carbon is efficiently distributed from leaves to heterotrophic tissues like fruit, flowers and roots. This long-distance transport happens in the highly specialized sieve elements of the phloem. In gymnosperms, sieve element anatomy appears to be less suited for mass flow of phloem sap than that of angiosperms. This review covers available data on gymnosperm phloem to evaluate if it functions differently from that of angiosperms. Although current evidence suggests that, despite a higher pathway resistance, a single source-to-sink turgor pressure gradient can drive mass flow, several questions remain unanswered. These include how endoplasmic reticulum-complexes in sieve elements influence flow, as well as what the effect of symplasmic coupling along the whole phloem pathway could be. Copyright © 2017 Elsevier Ltd. All rights reserved.

Mechanics of low-dimensional carbon nanostructures: Atomistic, continuum, and multi-scale approaches

NASA Astrophysics Data System (ADS)

Mahdavi, Arash

A new multiscale modeling technique called the Consistent Atomic-scale Finite Element (CAFE) method is introduced. Unlike traditional approaches for linking the atomic structure to its equivalent continuum, this method directly connects the atomic degrees of freedom to a reduced set of finite element degrees of freedom without passing through an intermediate homogenized continuum. As a result, there is no need to introduce stress and strain measures at the atomic level. The Tersoff-Brenner interatomic potential is used to calculate the consistent tangent stiffness matrix of the structure. In this finite element formulation, all local and non-local interactions between carbon atoms are taken into account using overlapping finite elements. In addition, a consistent hierarchical finite element modeling technique is developed for adaptively coarsening and refining the mesh over different parts of the model. This process is consistent with the underlying atomic structure and, by refining the mesh to the scale of atomic spacing, molecular dynamic results can be recovered. This method is valid across the scales and can be used to concurrently model atomistic and continuum phenomena so, in contrast with most other multi-scale methods, there is no need to introduce artificial boundaries for coupling atomistic and continuum regions. Effect of the length scale of the nanostructure is also included in the model by building the hierarchy of elements from bottom up using a finite size atom cluster as the building block. To be consistent with the bravais multi-lattice structure of sp2-bonded carbon, two independent displacement fields are used for reducing the order of the model. Sparse structure of the stiffness matrix of these nanostructures is exploited to reduce the memory requirement and to speed up the formation of the system matrices and solution of the equilibrium equations. Applicability of the method is shown with several examples of the nonlinear mechanics of carbon nanotubes and carbon nanocones subject to different loadings and boundary conditions. This finite element technique is also used to study the natural frequencies of low-dimensional carbon nanostructures and comparing the results with those of a homogenized isotropic continuum shell. Conclusion is that, replacing the atomic lattice with an isotropic continuum shell for a graphene sheet does not significantly affect the vibration frequencies while in the case of carbon nanotubes and carbon nanocones there is a significant difference between the natural frequencies of the atomistic model and its continuum counterpart. In the case of the carbon nanotube, continuum model successfully captures the beam bending vibration modes while overestimating frequencies of the modes in which the cross-section undergoes significant deformation. Furthermore, in the case of carbon nanotubes, the continuum shell exhibits a torsional mode which appears to be an artifact resulting from the small nominal thickness typically used in the continuum shell approximation of these nanostructures. Results of this study indicate that isotropic continuum shell models, while simple and useful in static analysis, cannot accurately predict the vibration frequencies of these nanostructures. We have studied the bistable nature of single-walled carbon nanotubes by investigating the change in the tube's energy as it is compressed between flat rigid indenters of various widths. Assuming the nanotube deformed uniformly along its length and modeling the cross-section as an inextensible, non-linear beam we found that tubes with a radius greater than 12 A are bistable and that tubes with a radius greater than 25 A have a lower energy in the collapsed state than in the inflated state. The difference in energy between the collapsed and inflated states decreases nearly linearly with increasing tube radius. While the inflated state remains stable for tubes of all diameters, the energy barrier keeping the tube from collapsing approaches zero as the tube radius increases. We also demonstrate why collapse with a wide indenter may be difficult to observe in narrow tubes. A reduced-order model is developed for the dynamics of the carbon nanotube atomic force microscope probes. Bending behavior of the nanotube probe is modeled using Euler's elastica. A nonlinear moment-curvature relationship is implemeneted to account for the ovalization of the cross section of the nanotube during bending. Van der Waal forces acting between tube and the substrate is integrated over the surface of the tube and used as distributed follower forces acting on the equivalent elastica. Approximating the behavior of the nanotube with an elastica proved to be a very effiecient technique for modeling these nanostructures.

Enhanced adsorption of humic acids on ordered mesoporous carbon compared with microporous activated carbon.

PubMed

Liu, Fengling; Xu, Zhaoyi; Wan, Haiqin; Wan, Yuqiu; Zheng, Shourong; Zhu, Dongqiang

2011-04-01

Humic acids are ubiquitous in surface and underground waters and may pose potential risk to human health when present in drinking water sources. In this study, ordered mesoporous carbon was synthesized by means of a hard template method and further characterized by X-ray diffraction, N2 adsorption, transition electron microscopy, elemental analysis, and zeta-potential measurement. Batch experiments were conducted to evaluate adsorption of two humic acids from coal and soil, respectively, on the synthesized carbon. For comparison, a commercial microporous activated carbon and nonporous graphite were included as additional adsorbents; moreover, phenol was adopted as a small probe adsorbate. Pore size distribution characterization showed that the synthesized carbon had ordered mesoporous structure, whereas the activated carbon was composed mainly of micropores with a much broader pore size distribution. Accordingly, adsorption of the two humic acids was substantially lower on the activated carbon than on the synthesized carbon, because of the size-exclusion effect. In contrast, the synthesized carbon and activated carbon showed comparable adsorption for phenol when the size-exclusion effect was not in operation. Additionally, we verified by size-exclusion chromatography studies that the synthesized carbon exhibited greater adsorption for the large humic acid fraction than the activated carbon. The pH dependence of adsorption on the three carbonaceous adsorbents was also compared between the two test humic acids. The findings highlight the potential of using ordered mesoporous carbon as a superior adsorbent for the removal of humic acids. Copyright © 2011 SETAC.

Uranium mineralization in fluorine-enriched volcanic rocks

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

Burt, D.M.; Sheridan, M.F.; Bikun, J.

1980-09-01

Several uranium and other lithophile element deposits are located within or adjacent to small middle to late Cenozoic, fluorine-rich rhyolitic dome complexes. Examples studied include Spor Mountain, Utah (Be-U-F), the Honeycomb Hills, Utah (Be-U), the Wah Wah Mountains, Utah (U-F), and the Black Range-Sierra Cuchillo, New Mexico (Sn-Be-W-F). The formation of these and similar deposits begins with the emplacement of a rhyolitic magma, enriched in lithophile metals and complexing fluorine, that rises to a shallow crustal level, where its roof zone may become further enriched in volatiles and the ore elements. During initial explosive volcanic activity, aprons of lithicrich tuffsmore » are erupted around the vents. These early pyroclastic deposits commonly host the mineralization, due to their initial enrichment in the lithophile elements, their permeability, and the reactivity of their foreign lithic inclusions (particularly carbonate rocks). The pyroclastics are capped and preserved by thick topaz rhyolite domes and flows that can serve as a source of heat and of additional quantities of ore elements. Devitrification, vapor-phase crystallization, or fumarolic alteration may free the ore elements from the glassy matrix and place them in a form readily leached by percolating meteoric waters. Heat from the rhyolitic sheets drives such waters through the system, generally into and up the vents and out through the early tuffs. Secondary alteration zones (K-feldspar, sericite, silica, clays, fluorite, carbonate, and zeolites) and economic mineral concentrations may form in response to this low temperature (less than 200 C) circulation. After cooling, meteoric water continues to migrate through the system, modifying the distribution and concentration of the ore elements (especially uranium).« less

Volatile elements - water, carbon, nitrogen, noble gases - on Earth

NASA Astrophysics Data System (ADS)

Marty, B.

2017-12-01

Understanding the origin and evolution of life-bearing volatile elements (water, carbon, nitrogen) on Earth is a fruitful and debated area of research. In his pioneering work, W.W. Rubey inferred that the terrestrial atmosphere and the oceans formed from degassing of the mantle through geological periods of time. Early works on noble gas isotopes were consistent with this view and proposed a catastrophic event of mantle degassing early in Earth's history. We now have evidence, mainly from noble gas isotopes, that several cosmochemical sources contributed water and other volatiles at different stages of Earth's accretion. Potential contributors include the protosolar nebula gas that equilibrated with magma oceans, inner solar system bodies now represented by chondrites, and comets. Stable isotope ratios suggest volatiles where primarily sourced by planetary bodies from the inner solar system. However, recent measurements by the European Space Agency Rosetta probe on the coma of Comet 67P/Churyumov-Gerasimenko permit to set quantitative constraints on the cometary contribution to the surface of our planet. The surface and mantle reservoirs volatile elements exchanged volatile elements through time, with rates that are still uncertain. Some mantle regions remained isolated from whole mantle convection within the first tens to hundreds million years after start of solar system formation. These regions, now sampled by some mantle plumes (e.g., Iceland, Eifel) preserved their volatile load, as indicated by extinct and extant radioactivity systems. The abundance of volatile elements in the mantle is still not well known. Different approaches, such as high pressure experimental petrology, noble gas geochemistry, modelling, resulted in somewhat contrasted estimates, varying over one order of magnitude for water. Comparative planetology, that is, the study of volatiles on the Moon, Venus, Mars, Vesta, will shed light on the sources and strengths of these elements in the inner solar system.

Development and characterization of self-healing carbon fabric/ionomer composite through stitched polymeric artificial muscle

NASA Astrophysics Data System (ADS)

Gabriel, Mark Joseph

Typical cracks in composite materials are hard to detect, because they may be very small or occur inside the material. This study investigates the development and characterization of carbon fiber and an ionomer, self-healing, laminate composite, enhanced with stitched artificial muscle elements. Although the carbon fiber is used as a structural reinforcement, the carbon fiber can also act as a resistive heating element in order to activate the healing elements in a Close-Then-Heal (CTH) approach. However in this study, hot air in an oven was used to activate the, SurlynRTM 8940, self-healing matrix. Artificial muscle was prepared from commercial fishing line to stitch reinforce the carbon laminate composite in the Z plane. Holes were drilled into the final composite and the muscle was stitched into the composite for active reinforcement. Differential scanning calorimetry was used to characterize the matrix and fishing line properties. The resulting smart composite was subjected to low velocity impact tests and consequential damage before healing in an oven, followed by three point bending flexure tests. Cracks in the carbon fiber reinforcement formed more easily than expected after impact because the holes were drilled to facilitate the muscle stitching. The matrix material could heal, but the reinforcement carbon could not. Several equipment issues and failures limited the amount of samples that could be created to continue testing with new parameters.

Fundamental aspects of recoupled pair bonds. I. Recoupled pair bonds in carbon and sulfur monofluoride

NASA Astrophysics Data System (ADS)

Dunning, Thom H.; Xu, Lu T.; Takeshita, Tyler Y.

2015-01-01

The number of singly occupied orbitals in the ground-state atomic configuration of an element defines its nominal valence. For carbon and sulfur, with two singly occupied orbitals in their 3P ground states, the nominal valence is two. However, in both cases, it is possible to form more bonds than indicated by the nominal valence—up to four bonds for carbon and six bonds for sulfur. In carbon, the electrons in the 2s lone pair can participate in bonding, and in sulfur the electrons in both the 3p and 3s lone pairs can participate. Carbon 2s and sulfur 3p recoupled pair bonds are the basis for the tetravalence of carbon and sulfur, and 3s recoupled pair bonds enable sulfur to be hexavalent. In this paper, we report generalized valence bond as well as more accurate calculations on the a4Σ- states of CF and SF, which are archetypal examples of molecules that possess recoupled pair bonds. These calculations provide insights into the fundamental nature of recoupled pair bonds and illustrate the key differences between recoupled pair bonds formed with the 2s lone pair of carbon, as a representative of the early p-block elements, and recoupled pair bonds formed with the 3p lone pair of sulfur, as a representative of the late p-block elements.

Water-quality, bed-sediment, and biological data (October 2013 through September 2014) and statistical summaries of data for streams in the Clark Fork Basin, Montana

USGS Publications Warehouse

Dodge, Kent A.; Hornberger, Michelle I.

2015-12-24

This report presents the analytical results and qualityassurance data for water-quality, bed-sediment, and biota samples collected at sites from October 2013 through September 2014. Water-quality data include concentrations of selected major ions, trace elements, and suspended sediment. At 12 sites, dissolved organic carbon and turbidity samples were collected. In addition, nitrogen (nitrate plus nitrite) samples were collected at two sites. Daily values of mean suspended-sediment concentration and suspended-sediment discharge were determined for four sites. Seasonal daily values of turbidity were determined for four sites. Bed-sediment data include trace-ele­ment concentrations in the fine-grained fraction. Biological data include trace-element concentrations in wholebody tissue of aquatic benthic insects. Statistical summaries of water-quality, bed-sediment, and biological data for sites in the upper Clark Fork Basin are provided for the period of record.

Progressive Damage Analysis of Bonded Composite Joints

NASA Technical Reports Server (NTRS)

Leone, Frank A., Jr.; Girolamo, Donato; Davila, Carlos G.

2012-01-01

The present work is related to the development and application of progressive damage modeling techniques to bonded joint technology. The joint designs studied in this work include a conventional composite splice joint and a NASA-patented durable redundant joint. Both designs involve honeycomb sandwich structures with carbon/epoxy facesheets joined using adhesively bonded doublers.Progressive damage modeling allows for the prediction of the initiation and evolution of damage within a structure. For structures that include multiple material systems, such as the joint designs under consideration, the number of potential failure mechanisms that must be accounted for drastically increases the complexity of the analyses. Potential failure mechanisms include fiber fracture, intraply matrix cracking, delamination, core crushing, adhesive failure, and their interactions. The bonded joints were modeled using highly parametric, explicitly solved finite element models, with damage modeling implemented via custom user-written subroutines. Each ply was discretely meshed using three-dimensional solid elements. Layers of cohesive elements were included between each ply to account for the possibility of delaminations and were used to model the adhesive layers forming the joint. Good correlation with experimental results was achieved both in terms of load-displacement history and the predicted failure mechanism(s).

Calcite and dolomite in intrusive carbonatites. II. Trace-element variations

NASA Astrophysics Data System (ADS)

Chakhmouradian, Anton R.; Reguir, Ekaterina P.; Couëslan, Christopher; Yang, Panseok

2016-04-01

The composition of calcite and dolomite from several carbonatite complexes (including a large set of petrographically diverse samples from the Aley complex in Canada) was studied by electron-microprobe analysis and laser-ablation inductively-coupled-plasma mass-spectrometry to identify the extent of substitution of rare-earth and other trace elements in these minerals and the effects of different igneous and postmagmatic processes on their composition. Analysis of the newly acquired and published data shows that the contents of rare-earth elements (REE) and certain REE ratios in magmatic calcite and dolomite are controlled by crystal fractionation of fluorapatite, monazite and, possibly, other minerals. Enrichment in REE observed in some samples (up to ~2000 ppm in calcite) cannot be accounted for by coupled substitutions involving Na, P or As. At Aley, the REE abundances and chondrite-normalized (La/Yb)cn ratios in carbonates decrease with progressive fractionation. Sequestration of heavy REE from carbonatitic magma by calcic garnet may be responsible for a steeply sloping "exponential" pattern and lowered Ce/Ce* ratios of calcite from Magnet Cove (USA) and other localities. Alternatively, the low levels of Ce and Mn in these samples could result from preferential removal of these elements by Ce4+- and Mn3+-bearing minerals (such as cerianite and spinels) at increasing f(O2) in the magma. The distribution of large-ion lithophile elements (LILE = Sr, Ba and Pb) in rock-forming carbonates also shows trends indicative of crystal fractionation effects (e.g., concomitant depletion in Ba + Pb at Aley, or Sr + Ba at Kerimasi), although the phases responsible for these variations cannot be identified unambiguously at present. Overall, element ratios sensitive to the redox state of the magma and its complexing characteristics (Eu/Eu*, Ce/Ce* and Y/Ho) are least variable and in both primary calcite and dolomite, approach the average chondritic values. In consanguineous rocks, calcite invariably has higher REE and LILE levels than dolomite. Hydrothermal reworking of carbonatites does not produce a unique geochemical fingerprint, leading instead to a variety of evolutionary trends that range from light-REE and LILE enrichment (Turiy Mys, Russia) to heavy-REE enrichment and LILE depletion (Bear Lodge, USA). These differences clearly attest to variations in the chemistry of carbonatitic fluids and, consequently, their ability to mobilize specific trace elements from earlier-crystallized minerals. An important telltale indicator of hydrothermal reworking is deviation from the primary, chondrite-like REE ratios (in particular, Y/Ho and Eu/Eu*), accompanied by a variety of other compositional changes depending on the redox state of the fluid (e.g., depletion of carbonates in Mn owing to its oxidation and sequestration by secondary oxides). The effect of supergene processes was studied on a single sample from Bear Lodge, which shows extreme depletion in Mn and Ce (both due to oxidation), coupled with enrichment in Pb and U, possibly reflecting an increased availability of Pb2+ and (UO2)2+ species in the system. On the basis of these findings, several avenues for future research can be outlined: (1) structural mechanisms of REE uptake by carbonates; (2) partitioning of REE and LILE between cogenetic calcite and dolomite; (3) the effects of fluorapatite, phlogopite and pyrochlore fractionation on the LILE budget of magmatic carbonates; (4) the cause(s) of coupled Mn-Ce depletion in some primary calcite; and (5) relations between fluid chemistry and compositional changes in hydrothermal carbonates.

Terrestrial organic carbon contributions to sediments on the Washington margin

NASA Astrophysics Data System (ADS)

Prahl, F. G.; Ertel, J. R.; Goni, M. A.; Sparrow, M. A.; Eversmeyer, B.

1994-07-01

Elemental and stable carbon isotopic compositions and biomarker concentrations were determined in sediments from the Columbia River basin and the Washington margin in order to evaluate geochemical approaches for quantifying terrestrial organic matter in marine sediments. The biomarkers include: an homologous series of long-chain n-alkanes derived from the surface waxes of higher plants; phenolic and hydroxyalkanoic compounds produced by CuO oxidation of two major vascular plant biopolymers, lignin and cutin. All marine sediments, including samples collected from the most remote sites in Cascadia Basin, showed organic geochemical evidence for the presence of terrestrial organic carbon. Using endmember values for the various biomarkers determined empirically by two independent means, we estimate that the terrestrial contribution to the Washington margin is ~ 60% for shelf sediments, ~ 30% for slope sediments, and decreases further to ≤15% in basin sediments. Results from the same geochemical measurements made with depth in gravity core 6705-7 from Cascadia Seachannel suggest that our approach to assess terrestrial organic carbon contributions to contemporary deposits on the Washington margin can be applied to the study of sediments depositing in this region since the last glacial period.

Metal-Element Compounds of Titanium, Zirconium, and Hafnium as Pyrotechnic Fuels

DTIC Science & Technology

2015-05-04

including ceramic materials in this role has been far less common. Following the development of boron carbide-based pyrotechnics in our laboratories, we...ameliorate these problems. Commercially available group 4 compounds containing hydrogen, boron , carbon, nitrogen, silicon, and phosphorus were obtained for...predicted behavior suggests that these compounds may be useful for a variety of pyrotechnic applications. 1. INTRODUCTION The recent use of boron

Utilization of waste of coal-mining enterprise in production of building materials

NASA Astrophysics Data System (ADS)

Chugunov, A. D.; Filatova, E. G.; Yakovleva, A. A.

2018-03-01

Wastes of coal producers often include substances allowing treating such wastes as valuable feeds for metallurgy, chemical and construction processes. This study concerned elemental and phase composition of samples obtained by calcination of bottom sediments of the coal producer spoil bank. The research has shown that the samples contain significant amounts of carbon, iron, silicon, aluminum and other valuable components.

Characterization and Recovery of Rare Earths from Coal and By-Products

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

Granite, Evan J.; Roth, Elliot; Alvin, Mary Anne

Coal is a precious resource, both in the United States and around the world. The United States has a 250-year supply of coal, and generates between 30 - 40% of its electricity through coal combustion. Approximately 1 Gt of coal has been mined annually in the US, although the 2015 total will likely be closer to 900 Mt (http://www.eia.gov/coal/production/quarterly/). Most of the coal is burned for power generation, but substantial quantities are also employed in the manufacture of steel, chemicals, and activated carbons. Coal has a positive impact upon many industries, including mining, power, rail transportation, manufacturing, chemical, steel, activatedmore » carbon, and fuels. Everything that is in the earth’s crust is also present within coal to some extent, and the challenge is always to utilize abundant domestic coal in clean and environmentally friendly manners. In the case of the rare earths, these valuable and extraordinarily useful elements are present within the abundant coal and coal by-products produced domestically and world-wide. These materials include the coals, as well as the combustion by-products such as ashes, coal preparation wastes, gasification slags, and mining by-products. All of these materials can be viewed as potential sources of rare earth elements. Most of the common inorganic lanthanide compounds, such as the phosphates found in coal, have very high melting, boiling, and thermal decomposition temperatures, allowing them to concentrate in combustion and gasification by-products. Furthermore, rare earths have been found in interesting concentrations in the strata above and below certain coal seams. Much of the recent research on coal utilization in the United States has focused upon the capture of pollutants such as acid gases, particulates, and mercury, and the greenhouse gas carbon dioxide. The possible recovery of rare earth and other critical elements from abundant coal and by-products is an exciting new research area, representing a dramatic paradigm shift for coal.« less

Thermostructural Analysis of Carbon Cloth Phenolic Material Tested at the Laser Hardened Material Evaluation Laboratory

NASA Technical Reports Server (NTRS)

Clayton, J. Louie; Ehle, Curt; Saxon, Jeff (Technical Monitor)

2002-01-01

RSRM nozzle liner components have been analyzed and tested to explore the occurrence of anomalous material performance known as pocketing erosion. Primary physical factors that contribute to pocketing seem to include the geometric permeability, which governs pore pressure magnitudes and hence load, and carbon fiber high temperature tensile strength, which defines a material limiting capability. The study reports on the results of a coupled thermostructural finite element analysis of Carbon Cloth Phenolic (CCP) material tested at the Laser Hardened Material Evaluation Laboratory (the LHMEL facility). Modeled test configurations will be limited to the special case of where temperature gradients are oriented perpendicular to the composite material ply angle. Analyses were conducted using a transient, one-dimensional flow/thermal finite element code that models pore pressure and temperature distributions and in an explicitly coupled formulation, passes this information to a 2-dimensional finite element structural model for determination of the stress/deformation behavior of the orthotropic fiber/matrix CCP. Pore pressures are generated by thermal decomposition of the phenolic resin which evolve as a multi-component gas phase which is partially trapped in the porous microstructure of the composite. The nature of resultant pressures are described by using the Darcy relationships which have been modified to permit a multi-specie mass and momentum balance including water vapor condensation. Solution to the conjugate flow/thermal equations were performed using the SINDA code. Of particular importance to this problem was the implementation of a char and deformation state dependent (geometric) permeability as describing a first order interaction between the flow/thermal and structural models. Material property models are used to characterize the solid phase mechanical stiffness and failure. Structural calculations were performed using the ABAQUS code. Iterations were made between the two codes involving the dependent variables temperature, pressure and across-ply strain level. Model results comparisons are made for three different surface heat rates and dependent variable sensitivities discussed for the various cases.

Behavior and Distribution of Heavy Metals Including Rare Earth Elements, Thorium, and Uranium in Sludge from Industry Water Treatment Plant and Recovery Method of Metals by Biosurfactants Application

PubMed Central

Gao, Lidi; Kano, Naoki; Sato, Yuichi; Li, Chong; Zhang, Shuang; Imaizumi, Hiroshi

2012-01-01

In order to investigate the behavior, distribution, and characteristics of heavy metals including rare earth elements (REEs), thorium (Th), and uranium (U) in sludge, the total and fractional concentrations of these elements in sludge collected from an industry water treatment plant were determined and compared with those in natural soil. In addition, the removal/recovery process of heavy metals (Pb, Cr, and Ni) from the polluted sludge was studied with biosurfactant (saponin and sophorolipid) elution by batch and column experiments to evaluate the efficiency of biosurfactant for the removal of heavy metals. Consequently, the following matters have been largely clarified. (1) Heavy metallic elements in sludge have generally larger concentrations and exist as more unstable fraction than those in natural soil. (2) Nonionic saponin including carboxyl group is more efficient than sophorolipid for the removal of heavy metals in polluted sludge. Saponin has selectivity for the mobilization of heavy metals and mainly reacts with heavy metals in F3 (the fraction bound to carbonates) and F5 (the fraction bound to Fe-Mn oxides). (3) The recovery efficiency of heavy metals (Pb, Ni, and Cr) reached about 90–100% using a precipitation method with alkaline solution. PMID:22693485

Impacts of disturbance history on annual carbon stocks and fluxes in southeastern US forests during 1986-2010 using remote sensing, forest inventory data, and a carbon cycle model

NASA Astrophysics Data System (ADS)

Gu, H.; Zhou, Y.; Williams, C. A.

2017-12-01

Accurate assessment of forest carbon storage and uptake is central to policymaking aimed at mitigating climate change and understanding the role forests play in the global carbon cycle. Disturbance events are highly heterogeneous in space and time, impacting forest carbon dynamics and challenging the quantification and reporting of carbon stocks and fluxes. This study documents annual carbon stocks and fluxes from 1986 and 2010 mapped at 30-m resolution across southeastern US forests, characterizing how they respond to disturbances and ensuing regrowth. Forest inventory data (FIA) are used to parameterize a carbon cycle model (CASA) to represent post-disturbance carbon trajectories of carbon pools and fluxes with time following harvest, fire and bark beetle disturbances of varying severity and across forest types and site productivity settings. Time since disturbance at 30 meters is inferred from two remote-sensing data sources: disturbance year (NAFD, MTBS and ADS) and biomass (NBCD 2000) intersected with FIA-derived curves of biomass accumulation with stand age. All of these elements are combined to map carbon stocks and fluxes at a 30-m resolution for the year 2010, and to march backward in time for continuous, annual reporting. Results include maps of annual carbon stocks and fluxes for forests of the southeastern US, and analysis of spatio-temporal patterns of carbon sources/sinks at local and regional scales.

Health impacts of frequent heavy automobile traffic on children and adolescents.

PubMed

Akpan, Akpan I

2004-01-01

This paper assesses the extent to which particulate, elemental and organic carbon emissions from heavy traffic in urban city roads affect the health of children and the adolescent health. Although the health effects of exposures may be cumulative, it is in the adolescence that the manifestations are realized. This paper therefore, assesses the best way forward for monitoring and preventing the environmental health impacts of heavy traffic on children and adolescents who live within the vicinity of urban city transportation systems. Major urban cities such as Houston, New York, and California are cited as examples of cities where health-related problems have already been reported. The particulate, elemental and organic carbon emissions are reviewed as the sources by which heavy traffic and the hazardous chemical emissions affect the health of the populace. The role of accessory loading and engine speed on idling emissions in direct health risks of children and adolescents is evaluated. The association of particulate, elemental, and organic carbon emission with respiratory effects (including, allergies and asthma), and the related behavior problems in children and the adolescents are discussed. The best strategies in preventing the effects of heavy traffic in the urban cities are suggested by introducing new effective monitoring techniques and exposure assessment methods. It is visualized that a more comprehensive research is needed to develop robust regulatory systems that would control the efficiency of automobiles and prevent the adverse health effects relating to heavy traffics in urban city roads. Strong city environmental health authorities-community partnerships relevant to exposure information should be encouraged.

Carbon fiber epoxy composites for both strengthening and health monitoring of structures.

PubMed

Salvado, Rita; Lopes, Catarina; Szojda, Leszek; Araújo, Pedro; Gorski, Marcin; Velez, Fernando José; Castro-Gomes, João; Krzywon, Rafal

2015-05-06

This paper presents a study of the electrical and mechanical behavior of several continuous carbon fibers epoxy composites for both strengthening and monitoring of structures. In these composites, the arrangement of fibers was deliberately diversified to test and understand the ability of the composites for self-sensing low strains. Composites with different arrangements of fibers and textile weaves, mainly unidirectional continuous carbon reinforced composites, were tested at the dynamometer. A two-probe method was considered to measure the relative electrical resistance of these composites during loading. The measured relative electrical resistance includes volume and contact electrical resistances. For all tested specimens, it increases with an increase in tensile strain, at low strain values. This is explained by the improved alignment of fibers and resulting reduction of the number of possible contacts between fibers during loading, increasing as a consequence the contact electrical resistance of the composite. Laboratory tests on strengthening of structural elements were also performed, making hand-made composites by the "wet process", which is commonly used in civil engineering for the strengthening of all types of structures in-situ. Results show that the woven epoxy composite, used for strengthening of concrete elements is also able to sense low deformations, below 1%. Moreover, results clearly show that this textile sensor also improves the mechanical work of the strengthened structural elements, increasing their bearing capacity. Finally, the set of obtained results supports the concept of a textile fabric capable of both structural upgrade and self-monitoring of structures, especially large structures of difficult access and needing constant, sometimes very expensive, health monitoring.

Carbon Fiber Epoxy Composites for Both Strengthening and Health Monitoring of Structures

PubMed Central

Salvado, Rita; Lopes, Catarina; Szojda, Leszek; Araújo, Pedro; Gorski, Marcin; Velez, Fernando José; Castro-Gomes, João; Krzywon, Rafal

2015-01-01

This paper presents a study of the electrical and mechanical behavior of several continuous carbon fibers epoxy composites for both strengthening and monitoring of structures. In these composites, the arrangement of fibers was deliberately diversified to test and understand the ability of the composites for self-sensing low strains. Composites with different arrangements of fibers and textile weaves, mainly unidirectional continuous carbon reinforced composites, were tested at the dynamometer. A two-probe method was considered to measure the relative electrical resistance of these composites during loading. The measured relative electrical resistance includes volume and contact electrical resistances. For all tested specimens, it increases with an increase in tensile strain, at low strain values. This is explained by the improved alignment of fibers and resulting reduction of the number of possible contacts between fibers during loading, increasing as a consequence the contact electrical resistance of the composite. Laboratory tests on strengthening of structural elements were also performed, making hand-made composites by the “wet process”, which is commonly used in civil engineering for the strengthening of all types of structures in-situ. Results show that the woven epoxy composite, used for strengthening of concrete elements is also able to sense low deformations, below 1%. Moreover, results clearly show that this textile sensor also improves the mechanical work of the strengthened structural elements, increasing their bearing capacity. Finally, the set of obtained results supports the concept of a textile fabric capable of both structural upgrade and self-monitoring of structures, especially large structures of difficult access and needing constant, sometimes very expensive, health monitoring. PMID:25954955

Occurrence and distribution of contaminants in bottom sediment and water of the Barron River Canal, Big Cypress National Preserve, Florida

USGS Publications Warehouse

Miller, Ronald L.; McPherson, Benjamin F.

2001-01-01

Trace elements and organic contaminants in bottom-sediment samples collected from 10 sites on the Barron River Canal and from one site on the Turner River in October 1998 had patterns of distribution that indicated different sources. At some sites on the Barron River Canal, lead, copper, and zinc, normalized to aluminum, exceeded limits normally considered as background and may be enriched by human activities. Polynuclear aromatic hydrocarbons and p-cresol, normalized against organic carbon, had patterns of distribution that indicated local sources of input from a road or vehicular traffic or from an old creosote wood treatment facility. Phthalate esters and the traces elements arsenic, cadmium, and zinc were more widely distributed with the highest normalized concentrations occurring at the Turner River background site, probably due to the high percentage of fine sediment (74% less than 63 micrometers) and high organic carbon concentration (42%) at that site and the binding effect of organic carbon on trace elements and trace organic compounds. Low concentrations of pesticides or pesticide degradation products were detected in bottom sediment (DDD and DDE, each less than 3.5 µg/kg) and water (9 pesticides, each less than 0.06 µ/L), primarily in the northern reach of the Barron River Canal where agriculture is a likely source. Although a few contaminants approached criteria that would indicate adverse effects on aquatic life, none exceeded the criteria, but the potential synergistic effects of mixtures of contaminants found at most sites are not included in the criteria.

Comparative study of ageing, heat treatment and accelerated carbonation for stabilization of municipal solid waste incineration bottom ash in view of reducing regulated heavy metal/metalloid leaching.

PubMed

Santos, Rafael M; Mertens, Gilles; Salman, Muhammad; Cizer, Özlem; Van Gerven, Tom

2013-10-15

This study compared the performance of four different approaches for stabilization of regulated heavy metal and metalloid leaching from municipal solid waste incineration bottom ash (MSWI-BA): (i) short term (three months) heap ageing, (ii) heat treatment, (iii) accelerated moist carbonation, and (iv) accelerated pressurized slurry carbonation. Two distinct types of MSWI-BA were tested in this study: one originating from a moving-grate furnace incineration operation treating exclusively household refuse (sample B), and another originating from a fluid-bed furnace incineration operation that treats a mixture of household and light industrial wastes (sample F). The most abundant elements in the ashes were Si (20-27 wt.%) and Ca (16-19 wt.%), followed by significant quantities of Fe, Al, Na, S, K, Mg, Ti, and Cl. The main crystalline substances present in the fresh ashes were Quartz, Calcite, Apatite, Anhydrite and Gehlenite, while the amorphous fraction ranged from 56 to 73 wt.%. The leaching values of all samples were compared to the Flemish (NEN 7343) and the Walloon (DIN 38414) regulations from Belgium. Batch leaching of the fresh ashes at natural pH showed that seven elements exceeded at least one regulatory limit (Ba, Cr, Cu, Mo, Pb, Se and Zn), and that both ashes had excess basicity (pH > 12). Accelerated carbonation achieved significant reduction in ash basicity (9.3-9.9); lower than ageing (10.5-12.2) and heat treatment (11.1-12.1). For sample B, there was little distinction between the leaching results of ageing and accelerated carbonation with respect to regulatory limits; however carbonation achieved comparatively lower leaching levels. Heat treatment was especially detrimental to the leaching of Cr. For sample F, ageing was ineffective and heat treatment had marginally better results, while accelerated carbonation delivered the most effective performance, with slurry carbonation meeting all DIN limits. Slurry carbonation was deemed the most effective treatment process, achieving consistently significant leaching stabilization, while also effectively washing out Cl ions, a requirement for the utilization of the ashes in construction applications. The benefits of carbonation were linked to the formation of significant quantities of Ca-carbonates, including appreciable quantities of the Aragonite polymorph formed in the slurry carbonated samples. Copyright © 2013 Elsevier Ltd. All rights reserved.

A Study of the Carbon Cycle Using NASA Observations and the GEOS Model

NASA Technical Reports Server (NTRS)

Pawson, Steven; Gelaro, Ron; Ott, Lesley; Putman, Bill; Chatterjee, Abhishek; Koster, Randy; Lee, Eunjee; Oda, Tom; Weir, Brad; Zeng, Fanwei

2018-01-01

The Goddard Earth Observing System (GEOS) model has been developed in the Global Modeling and Assimilation Office (GMAO) at NASA's Goddard Space Flight Center. From its roots in chemical transport and as a General Circulation Model, the GEOS model has been extended to an Earth System Model based on a modular construction using the Earth System Modeling Framework (ESMF), combining elements developed in house in the GMAO with others that are imported through collaborative research. It is used extensively for research and for product generation, both as a free-running model and as the core of the GMAO's data assimilation system. In recent years, the GMAO's modeling and assimilation efforts have been strongly supported by Piers Sellers, building on both his earlier legacy as an observationally oriented model developer and his post-astronaut career as a dynamic leader into new territory. Piers' long-standing interest in the carbon cycle and the combination of models with observations motivates this presentation, which will focus on the representation of the carbon cycle in the GEOS Earth System Model. Examples will include: (i) the progression from specified land-atmosphere surface fluxes to computations with an interactive model component (Catchment-CN), along with constraints on vegetation distributions using satellite observations; (ii) the use of high-resolution satellite observations to constrain human-generated inputs to the atmosphere; (iii) studies of the consistency of the observed atmospheric carbon dioxide concentrations with those in the model simulations. The presentation will focus on year-to-year variations in elements of the carbon cycle, specifically on how the observations can inform the representation of mechanisms in the model and lead to integrity in global carbon dioxide simulations. Further, applications of the GEOS model to the planning of new carbon-climate observations will be addressed, as an example of the work that was strongly supported by Piers in the last months of his leadership of Earth Science at NASA Goddard.

Compositional Analysis of Fine Particulate Matter in Fairbanks, Alaska

NASA Astrophysics Data System (ADS)

Nattinger, K.; Simpson, W. R.; Huff, D.

2015-12-01

Fairbanks, AK experiences extreme pollution episodes that result in winter violations of the fine particulate matter (PM2.5) National Ambient Air Quality Standards. This poses a significant health risk for the inhabitants of the area. These high levels result from trapping of pollution in a very shallow boundary layer due to local meteorology, but the role of primary (direct emission) of particulate matter versus secondary production (in the atmosphere) of particulate matter is not understood. Analysis of the PM2.5 composition is being conducted to provide insight into sources, trends, and chemistry. Methods are developed to convert carbon data from IMPROVE (post-2009 analysis method) to NIOSH (pre-2009 method) utilizing blank subtraction, sampler bias adjustment, and inter-method correlations from co-located samples. By converting all carbon measurements to a consistent basis, long-term trends can be analyzed. The approach shows excellent mass closure between PM2.5 mass reconstructed from constituents and gravimetric-analyzed mass. This approach could be utilized in other US locations where the carbon analysis methods also changed. Results include organic and inorganic fractional mass percentages, analyzed over an eight-year period for two testing sites in Fairbanks and two in the nearby city of North Pole. We focus on the wintertime (Nov—Feb) period when most air quality violations occur and find that the particles consist primarily of organic carbon, with smaller percentages of sulfate, elemental carbon, ammonium, and nitrate. The Fairbanks area PM2.5 organic carbon / elemental carbon partitioning matches the source profile of wood smoke. North Pole and Fairbanks PM2.5 have significant compositional differences, with North Pole having a larger percentage of organic matter. Mass loadings in SO42-, NO3-, and total PM2.5 mass correlate with temperature. Multi-year temporal trends show little if any change with a strong effect from temperature. Insights from this study regarding primary versus possible secondary PM2.5 production processes can help in identifying effective PM2.5 control strategies.

Cerium anomaly across the mid-Tournaisian carbon isotope excursion (TICE)

NASA Astrophysics Data System (ADS)

Jiang, G.; Morales, D. C.; Maharjan, D. K.

2015-12-01

The Early Mississippian (ca. 359-345 Ma) represents one of the most important greenhouse-icehouse climate transitions in Earth history. Closely associated with this critical transition is a prominent positive carbon isotope excursion (δ13C ≥ +5‰) that has been documented from numerous stratigraphic successions across the globe. This δ13C excursion, informally referred to as the TICE (mid-Tournaisian carbon isotope excursion) event, has been interpreted as resulting from enhanced organic carbon burial, with anticipated outcomes including the lowering of atmospheric CO2 and global cooling, the growth of continental ice sheets and sea-level fall, and the increase of ocean oxygenation and ocean redox changes. The casual relationship between these events has been addressed from various perspectives but not yet clearly demonstrated. To document the potential redox change associated with the perturbation of the carbon cycle, we have analyzed rare earth elements (REE) and trace elements across the TICE in two sections across a shallow-to-deep water transect in the southern Great Basin (Utah and Nevada), USA. In both sections, the REE data show a significant positive cerium (Ce) anomaly (Ce/Ce* = Ce/(0.5La+0.5Pr)). Prior to the positive δ13C shift, most Ce/Ce* values are around 0.3 (between 0.2 and 0.4). Across the δ13C peak, Ce/Ce* values increase up to 0.87, followed by a decrease back to 0.2~0.3 after the δ13C excursion (Figure 1). The positive Ce anomaly is best interpreted as recording expansion of oxygen minimum zone and anoxia resulted from increased primary production. This is consistent with a significant increase of nitrogen isotopes (δ15N) across the δ13C peak. Integration of the carbon, nitrogen, and REE data demonstrates a responsive earth systems change linked to the perturbation of the Early Mississippian carbon cycle.

Time-Series Radiocarbon Measurements Indicate Carbon Turnover Across Soil Fractions is Correlated With Productivity in a Long-Term Agricultural Experiment

NASA Astrophysics Data System (ADS)

Sanderman, J.; Baisden, W. T.; Creamer, C.; Farrell, M.; Fallon, S.

2016-12-01

Carbonatites and alkaline intrusions are important sources of REEs. Environmental risks related to these deposit types have been assessed through literature review and evaluation of the geochemical properties of representative samples of mill tailings and their leachates. The main ore mineral in carbonatite deposits is bastnasite [(Ce,La)(CO3)F], which is found with dolomite and calcite ( 65 %), barite (20 - 25 %), plus a number of minor accessory minerals including sulfides such as galena and pyrite. Generally, alkaline intrusion-related REE deposits either occur in layered complexes or with dikes and veins cutting alkaline intrusions. Such intrusions have a more diverse group of REE ore minerals that include fluorcarbonates, oxides, silicates, and phosphates. Ore also can include minor calcite and iron (Fe), lead (Pb), and zinc (Zn) sulfides. The acid-generating potential of both deposit types is low because of a predominance of carbonate minerals in the carbonatite deposits, the presence of feldspars and minor calcite in alkaline intrusion-related deposits, and to only minor to trace occurrence of potentially acid-generating sulfide minerals. Both deposit types, however, are produced by igneous and hydrothermal processes that enrich high-field strength, incompatible elements, which typically are excluded from common rock-forming minerals. Elements such as yttrium (Y), niobium Nb), zirconium (Zr), hafnium (Hf), tungsten (W), titanium (Ti), tantalum (Ta), scandium (Sc), thorium (Th), and uranium (U) can be characteristic of these deposits and may be of environmental concern. Most of these elements, including the REEs, but with the exception of U, have low solubilities in water at the near-neutral pH values expected around these deposits. Mill tailings from carbonatite deposits can exceed residential soil and sediment criteria for Pb, and leachates from mill tailings can exceed drinking water guidelines for Pb. The greatest environmental challenges, however, are linked to the presence of Th and U, although mineral hosts for these elements are moderately unreactive in the environment. Both deposit types can have mill tailings that exceed residential soil criteria for U. Uranium can be recovered as a byproduct to mitigate its environmental effects, but Th remains a waste product that requires management.

Organic Carbon and Trace Element Cycling in a River-Dominated Tidal Coastal Wetland System (Tampa Bay, FL, USA)

NASA Astrophysics Data System (ADS)

Moyer, R. P.; Smoak, J. M.; Engelhart, S. E.; Powell, C. E.; Chappel, A. R.; Gerlach, M. J.; Kemp, A.; Breithaupt, J. L.

2016-02-01

Tampa Bay is the largest open water, river-fed estuary in Florida (USA), and is characterized by the presence of both mangrove and salt marsh ecosystems. Both coastal wetland systems, and small rivers such as the ones draining into Tampa Bay have historically been underestimated in terms of their role in the global carbon and elemental cycles. Climate change and sea-level rise (SLR) are major threats in Tampa Bay and stand to disrupt hydrologic cycles, compromising sediment accumulation and the rate of organic carbon (OC) burial. This study evaluates organic carbon content, sediment accumulation, and carbon burial rates in salt marsh and mangrove ecosystems, along with measurements of fluxes of dissolved OC (DOC) and trace elements in the water column of the Little Manatee River (LMR) in Tampa Bay. The characterization of OC and trace elements in tidal rivers and estuaries is critical for quantitatively constraining these systems in local-to-regional scale biogeochemical budgets, and provide insight into biogeochemical processes occurring with the estuary and adjacent tidal wetlands. Material fluxes of DOC and trace elements were tied to discharge irrespective of season, and the estuarine habitats removed 15-65% of DOC prior to export to Tampa Bay and the Gulf of Mexico. Thus, material is available for cycling and burial within marsh and mangrove peats, however, LMR mangrove peats have higher OC content and burial rates than adjacent salt marsh peats. Sedimentary accretion rates in LMR marshes are not currently keeping pace with SLR, thus furthering the rapid marsh-to-mangrove conversions that have been seen in Tampa Bay over the past half-century. Additionally, wetlands in Tampa Bay tend to have a lower rate of carbon burial than other Florida tidal wetlands, demonstrating their high sensitivity to climate change and SLR.

[Reconstructed ambient light extinction coefficient and its contribution factors in Beijing in January, 2010].

PubMed

Zhu, Li-Hua; Tao, Jun; Chen, Zhong-Ming; Zhao, Yue; Zhang, Ren-Jian; Cao, Jun-Ji

2012-01-01

Aerosol samples for PM2.5 were collected from 1st January to 31st January 2010, in Beijing. The concentrations of organic carbon, elemental carbon, water-solubile ions and soil elements of all particle samples were determined by thermal/optical carbon analyzer, ion chromatography and X-ray fluorescence spectrometer, respectively. The scattering coefficients (b(sp)), absorbing coefficients (b(ap)) and meteorological parameters for this period were also measured. Ambient light extinction coefficients were reconstructed by IMPROVE formula and were compared with measured light extinction coefficients. The results showed that the average mass concentration of PM2.5 was (144.3 +/- 89.1) microg x m(-3) during campaigning period. The average values of measured b(ap), b(sp) and extinction coefficient (b(ext)) were (67.4 +/- 54.3), (328.5 +/- 353.8) and (395.9 +/- 405.2) Mm(-1), respectively. IMPROVE formula is suitable for source apportionment of light extinction coefficient in campaign period. The average value of calculated b'(ext) was (611 +/- 503) Mm(-1) in January, 2010. The major contributors to ambient light extinction coefficients included (NH4) 2SO4 (24.6%), NH4NO3 (11.6%), OM (45.5%), EC (11.9%) and FS (6.4%), respectively.

Non-Intrusive, Distributed Gas Sensing Technology for Advanced Spacesuits

NASA Technical Reports Server (NTRS)

Delgado, Jesus; Phillips, Straun; Rubtsov, Vladimir; Chullen, Cinda

2015-01-01

Chemical sensors for monitoring gas composition, including oxygen, humidity, carbon dioxide, and trace contaminants are needed to characterize and validate spacesuit design and operating parameters. This paper reports on the first prototypes of a non-intrusive gas sensing technology based on flexible sensitive patches positioned inside spacesuit prototypes and interrogated by optical fibers routed outside the suit, taking advantage of the transparent materials of the suit prototypes. The sensitive patches are based on luminescent materials whose emission parameters vary with the partial pressure of a specific gas. Patches sensitive to carbon dioxide, humidity, oxygen, and ammonia have been developed, and their preliminary characterization in the laboratory using Mark III-like helmet parts is described. The first prototype system consists of a four-channel fiber optic luminescent detector that can be used to monitor any of the selected target gases at four locations. To switch from one gas to another we replace the (disposable) sensor patches and adjust the system settings. Repeatability among sensitive patches and of sensor performance from location to location has been confirmed, assuring that suit engineers will have flexibility in selecting multiple sensing points, fitting the sensor elements into the spacesuit, and easily repositioning the sensor elements as desired. The evaluation of the first prototype for monitoring carbon dioxide during washout studies in a space suit prototype is presented.

Effects of cobalt precursor on pyrolyzed carbon-supported cobalt-polypyrrole as electrocatalyst toward oxygen reduction reaction

PubMed Central

2013-01-01

A series of non-precious metal electrocatalysts, namely pyrolyzed carbon-supported cobalt-polypyrrole, Co-PPy-TsOH/C, are synthesized with various cobalt precursors, including cobalt acetate, cobalt nitrate, cobalt oxalate, and cobalt chloride. The catalytic performance towards oxygen reduction reaction (ORR) is comparatively investigated with electrochemical techniques of cyclic voltammogram, rotating disk electrode and rotating ring-disk electrode. The results are analyzed and discussed employing physiochemical techniques of X-ray diffraction, transmission electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, inductively coupled plasma, elemental analysis, and extended X-ray absorption fine structure. It shows that the cobalt precursor plays an essential role on the synthesis process as well as microstructure and performance of the Co-PPy-TsOH/C catalysts towards ORR. Among the studied Co-PPy-TsOH/C catalysts, that prepared with cobalt acetate exhibits the best ORR performance. The crystallite/particle size of cobalt and its distribution as well as the graphitization degree of carbon in the catalyst greatly affects the catalytic performance of Co-PPy-TsOH/C towards ORR. Metallic cobalt is the main component in the active site in Co-PPy-TsOH/C for catalyzing ORR, but some other elements such as nitrogen are probably involved, too. PMID:24229351

Non-Intrusive, Distributed Gas Sensing Technology for Advanced Spacesuits

NASA Technical Reports Server (NTRS)

Delgado, Jesus; Phillips, Straun; Rubtsov, Vladimir; Chullen, Cinda

2015-01-01

Chemical sensors for monitoring gas composition, including oxygen, humidity, carbon dioxide, and trace contaminants, are needed to characterize and validate spacesuit design and operating parameters. This paper reports on the first prototypes of a non-intrusive gas sensing technology based on flexible sensitive patches positioned inside spacesuit prototypes and interrogated via optical fibers routed outside the suit, taking advantage of the transparent materials of the suit prototypes. The sensitive patches are based on luminescent materials whose emission parameters vary with the partial pressure of a specific gas. Patches sensitive to carbon dioxide, humidity, and temperature have been developed, and their preliminary laboratory characterization in Mark III-like helmet parts is described. The first prototype system consists of a four-channel fiber optic luminescent detector that can be used to monitor any of the selected target gases at four locations. To switch from one gas to another we replace the (disposable) sensor patches and adjust the system settings. Repeatability among sensitive patches and of sensor performance from location to location has been confirmed, assuring that suit engineers will have flexibility in selecting multiple sensing points, fitting the sensor elements into the spacesuit, and easily repositioning the sensor elements as desired. The evaluation of the first prototype for monitoring carbon dioxide during washout studies in a spacesuit prototype is presented.

Characterization of the reaction products and precipitates at the interface of carbon fiber reinforced magnesium–gadolinium composite

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

Wang, Yaping; Jiang, Longtao, E-mail: longtaojiang@163.com; Chen, Guoqin

2016-03-15

In the present work, carbon fiber reinforced magnesium-gadolinium composite was fabricated by pressure infiltration method. The phase composition, micro-morphology, and crystal structure of reaction products and precipitates at the interface of the composite were investigated. Scanning electron microscopy and energy dispersive spectroscopy analysis revealed the segregation of gadolinium element at the interface between carbon fiber and matrix alloy. It was shown that block-shaped Gd4C5, GdC2 and nano-sized Gd2O3 were formed at the interface during the fabrication process due to the interfacial reaction. Furthermore, magnesium-gadolinium precipitates including needle-like Mg5Gd (or Mg24Gd5) and thin plate-shaped long period stacking-ordered phase, were also observedmore » at the interface and in the matrix near the interface. The interfacial microstructure and bonding mode were influenced by these interfacial products, which were beneficial for the improvement of the interfacial bonding strength. - Highlights: • Gadolinium element segregated on the surface of carbon fibers. • Block-shaped Gd{sub 4}C{sub 5} and GdC{sub 2} were formed at the interface via chemical reaction. • Gadolinium and oxygen reacted at the interface and formed nano-scaled Gd{sub 2}O{sub 3}. • The precipitates formed in the interface were identified to be Mg{sub 5}Gd (or Mg{sub 24}Gd{sub 5}) and plate-shaped long period stacking-ordered phase.« less

[Study on nutrient and salinity in soil covered with different vegetations in Shuangtaizi estuarine wetlands].

PubMed

Song, Xiao-Lin; Lü, Xian-Guo; Zhang, Zhong-Sheng; Chen, Zhi-Ke; Liu, Zheng-Mao

2011-09-01

Nutrient elements and salinity in soil covered by different vegetations including Phragmites australis (Clay.) Trin., Typha orientalis Presl., Puccinellia distans Parl, and Suaeda salsa in Shuangtaizi estuarine wetlands were investigated to study their distribution characteristics and to reveal the nutrient element variation during the vegetation succession processes. Results indicated that total potassium, total phosphorus and salinity were different significantly in soil between different plant communities while available phosphorus, total nitrogen, available nitrogen, available potassium, total sulfur, iron and soil organic carbon were different insignificantly. Correlation analysis suggested that soil organic carbon were related significantly to total nitrogen, available phosphorus, available potassium, which implied that decomposition of plant litter might be the mail source of soil nitrogen and available nutrient. Salinity was significantly related to total phosphorus and iron in soil. In Shuangtaizi estuarine wetland soil, ratios of carbon to nitrogen (R(C/N)) was in the range of 12.21-26.33 and the average value was 18.21, which was higher than 12.0. It indicated that soil organic carbon in Shuangtaizi estuarine mainly came from land but not ocean and plants contributed the most of soil organic matters. There was no significant difference in R(C/N) between soil from the four plant communities (F = 1.890, p = 0.151). R(C/N) was related significantly to sol salinity (r = 0.346 3, p = 0.035 8) and was increasing with soil salinity.

DOES A DIFFERENTIATED, CARBONATE-RICH, ROCKY OBJECT POLLUTE THE WHITE DWARF SDSS J104341.53+085558.2?

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

Melis, Carl; Dufour, P., E-mail: cmelis@ucsd.edu

We present spectroscopic observations of the dust- and gas-enshrouded, polluted, single white dwarf star SDSS J104341.53+085558.2 (hereafter SDSS J1043+0855). Hubble Space Telescope Cosmic Origins Spectrograph far-ultraviolet spectra combined with deep Keck HIRES optical spectroscopy reveal the elements C, O, Mg, Al, Si, P, S, Ca, Fe, and Ni and enable useful limits for Sc, Ti, V, Cr, and Mn in the photosphere of SDSS J1043+0855. From this suite of elements we determine that the parent body being accreted by SDSS J1043+0855 is similar to the silicate Moon or the outer layers of Earth in that it is rocky and iron-poor.more » Combining this with comparison to other heavily polluted white dwarf stars, we are able to identify the material being accreted by SDSS J1043+0855 as likely to have come from the outermost layers of a differentiated object. Furthermore, we present evidence that some polluted white dwarfs (including SDSS J1043+0855) allow us to examine the structure of differentiated extrasolar rocky bodies. Enhanced levels of carbon in the body polluting SDSS J1043+0855 relative to the Earth–Moon system can be explained with a model where a significant amount of the accreted rocky minerals took the form of carbonates; specifically, through this model the accreted material could be up to 9% calcium-carbonate by mass.« less

FRACTIONAL DISTILLATION SEPARATION OF PLUTONIUM VALUES FROM LIGHT ELEMENT VALUES

DOEpatents

Cunningham, B.B.

1957-12-17

A process is described for removing light element impurities from plutonium. It has been found that plutonium contaminated with impurities may be purified by converting the plutonium to a halide and purifying the halide by a fractional distillation whereby impurities may be distilled from the plutonium halide. A particularly effective method includes the step of forming a lower halide such as the trior tetrahalide and distilling the halide under conditions such that no decomposition of the halide occurs. Molecular distillation methods are particularly suitable for this process. The apparatus may comprise an evaporation plate with means for heating it and a condenser surface with means for cooling it. The condenser surface is placed at a distance from the evaporating surface less than the mean free path of molecular travel of the material being distilled at the pressure and temperature used. The entire evaporating system is evacuated until the pressure is about 10/sup -4/ millimeters of mercury. A high temperuture method is presented for sealing porous materials such as carbon or graphite that may be used as a support or a moderator in a nuclear reactor. The carbon body is subjected to two surface heats simultaneously in an inert atmosphere; the surface to be sealed is heated to 1500 degrees centigrade; and another surface is heated to 300 degrees centigrade, whereupon the carbon vaporizes and flows to the cooler surface where it is deposited to seal that surface. This method may be used to seal a nuclear fuel in the carbon structure.

78 FR 10546 - Approval and Promulgation of Implementation Plans; State of Alaska; Regional Haze State...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-02-14

... submittal identifies organic carbon emissions from natural wildfires as the primary contributor to... 20% worst days in Denali National Park were composed of organic carbon from natural fires. Alaska... Organic Matter Carbon (OMC) and Elemental Carbon (EC), it attributes all OMC and EC in the Denali region...

Carbonation of Subduction Interface Ultramafic Rocks and Implications for Deep Carbon Cycling: Evidence from Hybrid Serpentinite-Marble in the Voltri Massif, Italy

NASA Astrophysics Data System (ADS)

Scambelluri, M.; Bebout, G. E.; Gilio, M.; Belmonte, D.; Campomenosi, N.; Crispini, L.

2015-12-01

Release of COH fluids from hydrous minerals and carbonates influences element recycling and magmatism at subduction zones. Contradictory interpretations exist regarding the retention/storage of C in subducting plates and in the forearc to subarc mantle. Multiple lines of evidence indicate mobility of C in forearcs; however, the magnitude of this loss is highly uncertain[1-5]. A poorly constrained fraction of the 40-115 Mt/y of C initially subducted is released into fluids (e.g., by decarbonation, carbonate dissolution), and 18-43 Mt/y is returned at arc volcanoes[2-5, refs. therein]. The imbalance could reflect subduction into the deeper mantle or forearc/subarc storage[4-7]. We examine the fate of C in slab/interface ultramafic rocks, and by analogy serpentinized mantle wedge, via study of fluid-rock evolution of marble and variably carbonated serpentinite (Ligurian Alps). Based on petrography, and major/trace element and C and O isotope compositions, we demonstrate that serpentinite dehydration at 2-2.5 GPa, 550°C released aqueous fluids triggering breakdown of dolomite in nearby marbles, thus releasing C into fluids. Carbonate + olivine veins document flow of COH fluids; interaction of these COH fluids with serpentinite led to formation of high-pressure carbonated ultramafic-rock domains, thus resulting in retention of C in some rocks at an ancient subduction interface. We stress that lithologically complex interfaces could contain sites of both C release and C addition, further confounding estimates of net C loss at forearc and subarc depths [cf 4,5]. Sites of C retention, also including carbonate veins and graphite as reduced carbonate[7], could influence the transfer of slab C to at least the depths beneath volcanic fronts. 1. Poli S et al. 2009 EPSL; 2. Ague and Nicolescu 2014 Nat Geosci; 3. Cook-Collars et al. 2014 Chem Geol; 4. Collins et al. 2015 Chem Geol; 5. Kelemen and Manning 2015 PNAS; 6. Sapienza et al. 2009 CMP; 7 Galvez et al. 2013 Nat Geosci

Application of an ecosystem model to evaluate the importance of different processes and food web structure for transfer of 13 elements in a shallow lake.

PubMed

Konovalenko, L; Bradshaw, C; Andersson, E; Kautsky, U

2017-04-01

In environmental risk assessments of nuclear waste, there is need to estimate the potential risks of a large number of radionuclides over a long time period during which the environment is likely to change. Usually concentration ratios (CRs) are used to calculate the activity concentrations in organisms. However, CRs are not available for all radionuclides and they are not easily scalable to the varying environment. Here, an ecosystem transport model of elements, which estimates concentrations in organisms using carbon flows and food transfer instead of CR is presented. It is a stochastic compartment model developed for Lake Eckarfjärden at Forsmark in Sweden. The model was based on available data on carbon circulation, physical and biological processes from the site and identifies 11 functional groups of organisms. The ecosystem model was used to estimate the environmental transfer of 13 elements (Al, Ca, Cd, Cl, Cs, I, Ni, Nb, Pb, Se, Sr, Th, U) to various aquatic organisms, using element-specific distribution coefficients for suspended particles (K d PM ) and upper sediment (K d sed ), and subsequent transfer in the foodweb. The modelled CRs for different organism groups were compared with measured CRs from the lake and literature data, and showed good agreement for many elements and organisms, particularly for lower trophic levels. The model is, therefore, proposed as an alternative to measured CR, though it is suggested to further explore active uptake, assimilation and elimination processes to get better correspondence for some of the elements. The benthic organisms (i.e. bacteria, microphytobenthos and macroalgae) were identified as more important than pelagic organisms for transfer of elements to top predators. The element transfer model revealed that most of the radionuclides were channelled through the microbial loop, despite the fact that macroalgae dominated the carbon fluxes in this lake. Thus, element-specific adsorption of elements to the surface of aquatic species, that may be food sources for organisms at higher trophic levels, needs to be considered in combination with generic processes described by carbon fluxes. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Reduced sediment melting at 7.5-12 GPa: phase relations, geochemical signals and diamond nucleation

NASA Astrophysics Data System (ADS)

Brey, G. P.; Girnis, A. V.; Bulatov, V. K.; Höfer, H. E.; Gerdes, A.; Woodland, A. B.

2015-08-01

Melting of carbonated sediment in the presence of graphite or diamond was experimentally investigated at 7.5-12 GPa and 800-1600 °C in a multianvil apparatus. Two starting materials similar to GLOSS of Plank and Langmuir (Chem Geol 145:325-394, 1998) were prepared from oxides, carbonates, hydroxides and graphite. One mixture (Na-gloss) was identical in major element composition to GLOSS, and the other was poorer in Na and richer in K (K-gloss). Both starting mixtures contained ~6 wt% CO2 and 7 wt% H2O and were doped at a ~100 ppm level with a number of trace elements, including REE, LILE and HFSE. The near-solidus mineral assemblage contained a silica polymorph (coesite or stishovite), garnet, kyanite, clinopyroxene, carbonates (aragonite and magnesite-siderite solid solution), zircon, rutile, bearthite and hydrous phases (phengite and lawsonite at <9 GPa and the hydrous aluminosilicates topaz-OH and phase egg at >10 GPa). Hydrous phases disappear at ~900 °C, and carbonates persist up to 1000-1100 °C. At temperatures >1200 °C, the mineral assemblage consists of coesite or stishovite, kyanite and garnet. Clinopyroxene stability depends strongly on the Na content in the starting mixture; it remains in the Na-gloss composition up to 1600 °C at 12 GPa, but was not observed in K-gloss experiments above 1200 °C. The composition of melt or fluid changes gradually with increasing temperature from hydrous carbonate-rich (<10 wt% SiO2) at 800-1000 °C to volatile-rich silicate liquids (up to 40 wt% SiO2) at high temperatures. Trace elements were analyzed in melts and crystalline phases by LA ICP MS. The garnet-melt and clinopyroxene-melt partition coefficients are in general consistent with results from the literature for volatile-free systems and silicocarbonate melts derived by melting carbonated peridotites. Most trace elements are strongly incompatible in kyanite and silica polymorphs ( D < 0.01), except for V, Cr and Ni, which are slightly compatible in kyanite ( D > 1). Aragonite and Fe-Mg carbonate have very different REE partition coefficients ( D Mst-Sd/L ~ 0.01 and D Arg/L ~ 1). Nb, Ta, Zr and Hf are strongly incompatible in both carbonates. The bearthite/melt partition coefficients are very high for LREE (>10) and decrease to ~1 for HREE. All HFSE are strongly incompatible in bearthite. In contrast, Ta, Nb, Zr and Hf are moderately to strongly compatible in ZrSiO4 and TiO2 phases. Based on the obtained partition coefficients, the composition of a mobile phase derived by sediment melting in deep subduction zones was calculated. This phase is strongly enriched in incompatible elements and displays a pronounced negative Ta-Nb anomaly but no Zr-Hf anomaly. Although all experiments were conducted in the diamond stability field, only graphite was observed in low-temperature experiments. Spontaneous diamond nucleation and the complete transformation of graphite to diamond were observed at temperatures above 1200-1300 °C. We speculate that the observed character of graphite-diamond transformation is controlled by relationships between the kinetics of metastable graphite dissolution and diamond nucleation in a hydrous silicocarbonate melt that is oversaturated in C.

Rare earth element geochemistry of shallow carbonate outcropping strata in Saudi Arabia: Application for depositional environments prediction

NASA Astrophysics Data System (ADS)

Eltom, Hassan A.; Abdullatif, Osman M.; Makkawi, Mohammed H.; Eltoum, Isam-Eldin A.

2017-03-01

The interpretation of depositional environments provides important information to understand facies distribution and geometry. The classical approach to interpret depositional environments principally relies on the analysis of lithofacies, biofacies and stratigraphic data, among others. An alternative method, based on geochemical data (chemical element data), is advantageous because it can simply, reproducibly and efficiently interpret and refine the interpretation of the depositional environment of carbonate strata. Here we geochemically analyze and statistically model carbonate samples (n = 156) from seven sections of the Arab-D reservoir outcrop analog of central Saudi Arabia, to determine whether the elemental signatures (major, trace and rare earth elements [REEs]) can be effectively used to predict depositional environments. We find that lithofacies associations of the studied outcrop (peritidal to open marine depositional environments) possess altered REE signatures, and that this trend increases stratigraphically from bottom-to-top, which corresponds to an upward shallowing of depositional environments. The relationship between REEs and major, minor and trace elements indicates that contamination by detrital materials is the principal source of REEs, whereas redox condition, marine and diagenetic processes have minimal impact on the relative distribution of REEs in the lithofacies. In a statistical model (factor analysis and logistic regression), REEs, major and trace elements cluster together and serve as markers to differentiate between peritidal and open marine facies and to differentiate between intertidal and subtidal lithofacies within the peritidal facies. The results indicate that statistical modelling of the elemental composition of carbonate strata can be used as a quantitative method to predict depositional environments and regional paleogeography. The significance of this study lies in offering new assessments of the relationships between lithofacies and geochemical elements by using advanced statistical analysis, a method that could be used elsewhere to interpret depositional environment and refine facies models.

Elemental calcium intake associated with calcium acetate/calcium carbonate in the treatment of hyperphosphatemia

PubMed Central

Wilson, Rosamund J; Copley, J Brian

2017-01-01

Background Calcium-based and non-calcium-based phosphate binders have similar efficacy in the treatment of hyperphosphatemia; however, calcium-based binders may be associated with hypercalcemia, vascular calcification, and adynamic bone disease. Scope A post hoc analysis was carried out of data from a 16-week, Phase IV study of patients with end-stage renal disease (ESRD) who switched to lanthanum carbonate monotherapy from baseline calcium acetate/calcium carbonate monotherapy. Of the intent-to-treat population (N=2520), 752 patients with recorded dose data for calcium acetate (n=551)/calcium carbonate (n=201) at baseline and lanthanum carbonate at week 16 were studied. Elemental calcium intake, serum phosphate, corrected serum calcium, and serum intact parathyroid hormone levels were analyzed. Findings Of the 551 patients with calcium acetate dose data, 271 (49.2%) had an elemental calcium intake of at least 1.5 g/day at baseline, and 142 (25.8%) had an intake of at least 2.0 g/day. Mean (95% confidence interval [CI]) serum phosphate levels were 6.1 (5.89, 6.21) mg/dL at baseline and 6.2 (6.04, 6.38) mg/dL at 16 weeks; mean (95% CI) corrected serum calcium levels were 9.3 (9.16, 9.44) mg/dL and 9.2 (9.06, 9.34) mg/dL, respectively. Of the 201 patients with calcium carbonate dose data, 117 (58.2%) had an elemental calcium intake of at least 1.5 g/day, and 76 (37.8%) had an intake of at least 2.0 g/day. Mean (95% CI) serum phosphate levels were 5.8 (5.52, 6.06) mg/dL at baseline and 5.8 (5.53, 6.05) mg/dL at week 16; mean (95% CI) corrected serum calcium levels were 9.7 (9.15, 10.25) mg/dL and 9.2 (9.06, 9.34) mg/dL, respectively. Conclusion Calcium acetate/calcium carbonate phosphate binders, taken to control serum phosphate levels, may result in high levels of elemental calcium intake. This may lead to complications related to calcium balance. PMID:28182142

Low temperature-pressure batch experiments and field push-pull tests: Assessing potential effects of an unintended CO2 release from CCUS projects on groundwater chemistry

NASA Astrophysics Data System (ADS)

Mickler, P. J.; Yang, C.; Lu, J.; Reedy, R. C.; Scanlon, B. R.

2012-12-01

Carbon Capture Utilization and Storage projects (CCUS), where CO2 is captured at point sources such as power stations and compressed into a supercritical liquid for underground storage, has been proposed to reduce atmospheric CO2 and mitigate global climate change. Problems may arise from CO2 releases along discreet pathways such as abandoned wells and faults, upwards and into near surface groundwater. Migrating CO2 may inversely impact fresh water resources by increasing mineral solubility and dissolution rates and mobilizing harmful trace elements including As and Pb. This study addresses the impacts on fresh water resources through a combination of laboratory batch experiments, where aquifer sediment are reacted in their corresponding groundwater in 100% CO2 environments, and field push-pull tests where groundwater is equilibrated with 100% CO2, reacted in-situ in the groundwater system, and pulled out for analyses. Batch experiments were performed on aquifer material from carbonate dominated, mixed carbonate/silicalstic, and siliclastic dominated systems. A mixed silicalstic/carbonate system was chosen for the field based push-pull test. Batch experiment results suggest carbonate dissolution increased the concentration of Ca, Mg, Sr, Ba, Mn, U and HCO3- in groundwater. In systems with significant carbonate content, dissolution continued until carbonate saturation was achieved at approximately 1000 hr. Silicate dissolution increased the conc. of Si, K Ni and Co, but at much lower rates than carbonate dissolution. The elements As, Mo, V, Zn, Se and Cd generally show similar behavior where concentrations initially increase but soon drop to levels at or below the background concentrations (~48 hours). A Push-Pull test on one aquifer system produced similar geochemical behavior but observed reaction rates are higher in batch experiments relative to push-pull tests. Release of CO2 from CCUS sites into overlying aquifer systems may adversely impact groundwater quality primarily through carbonate dissolution which releases Ca and elements that substitute for Ca in crystal lattices. Silicate weathering releases primarily Si and K at lower rates. Chemical changes with the addition of CO2 may initially mobilize As, Mo, V, Zn, Se and Cd but these elements become immobile in the lowered pH water and sorb onto aquifer minerals. A combined laboratory batch experiment and field push-pull test in fresh water aquifers overlying CCUS projects will best characterize the response of the aquifer to increased pCO2. The long experimental duration of the batch experiments may allow reactions to reach equilibrium however; reaction rates may be artificially high due to increased mineral surface areas. Field based push-pull tests offer a more realistic water rock ratio and test a much larger volume of aquifer material but the test must be shorter in duration because the high pCO2 water is subject to mixing with low pCO2 background water and migration away from the test well with groundwater flow. A comparison of the two methods best characterizes the potential effects on groundwater chemistry

Whole body-element composition of Atlantic salmon Salmo salar influenced by migration direction and life stage in three distinct populations.

PubMed

Ebel, J D; Leroux, S J; Robertson, M J; Dempson, J B

2016-11-01

Body-element content was measured for three life stages of wild Atlantic salmon Salmo salar from three distinct Newfoundland populations as individuals crossed between freshwater and marine ecosystems. Life stage explained most of the variation in observed body-element concentration whereas river of capture explained very little variation. Element composition of downstream migrating post-spawn adults (i.e. kelts) and juvenile smolts were similar and the composition of these two life stages strongly differed from adults migrating upstream to spawn. Low variation within life stages and across populations suggests that S. salar may exert rheostatic control of their body-element composition. Additionally, observed differences in trace element concentration between adults and other life stages were probably driven by the high carbon concentration in adults because abundant elements, such as carbon, can strongly influence the observed concentrations of less abundant elements. Thus, understanding variation among individuals in trace elements composition requires the measurement of more abundant elements. Changes in element concentration with ontogeny have important consequences the role of fishes in ecosystem nutrient cycling and should receive further attention. © 2016 The Fisheries Society of the British Isles.

Microbenthic distribution of Proterozoic tidal flats: environmental and taphonomic considerations

NASA Technical Reports Server (NTRS)

Kah, L. C.; Knoll, A. H.

1996-01-01

Silicified carbonates of the late Mesoproterozoic to early Neoproterozoic Society Cliffs Formation, Baffin Island, contain distinctive microfabrics and microbenthic assemblages whose paleo-environmental distribution within the formation parallels the distribution of these elements through Proterozoic time. In the Society Cliffs Formation, restricted carbonates--including microdigitate stromatolites, laminated tufa, and tufted microbial mats--consist predominantly of synsedimentary cements; these facies and the cyanobacterial fossils they contain are common in Paleoproterozoic successions but rare in Neoproterozoic and younger rocks. Less restricted tidal-flat facies in the formation are composed of laminated microbialites dominated by micritic carbonate lithified early, yet demonstrably after compaction; these strata contain cyanobacteria that are characteristic in Neoproterozoic rocks. Within the formation, the facies-dependent distribution of microbial populations reflects both the style and timing of carbonate deposition because of the strong substrate specificity of benthic cyanobacteria. A reasonable conclusion is that secular changes in microbenthic assemblages through Proterozoic time reflect a decrease in the overall representation of rapidly lithified carbonate substrates in younger peritidal environments, as well as concomitant changes in the taphonomic window of silicification through which early life is observed.

Characterization of PM 2.5 collected during broadcast and slash-pile prescribed burns of predominately ponderosa pine forests in northern Arizona

NASA Astrophysics Data System (ADS)

Robinson, Marin S.; Zhao, Min; Zack, Lindsay; Brindley, Christine; Portz, Lillian; Quarterman, Matthew; Long, Xiufen; Herckes, Pierre

2011-04-01

Prescribed burning, in combination with mechanical thinning, is a successful method for reducing heavy fuel loads from forest floors and thereby lowering the risk of catastrophic wildfire. However, an undesirable consequence of managed fire is the production of fine particulate matter or PM 2.5 (particles ≤2.5 μm in aerodynamic diameter). Wood-smoke particulate data from 21 prescribed burns are described, including results from broadcast and slash-pile burns. All PM 2.5 samples were collected in situ on day 1 (ignition) or day 2. Samples were analyzed for mass, polycyclic aromatic hydrocarbons (PAHs), inorganic elements, organic carbon (OC), and elemental carbon (EC). Results were characteristic of low-intensity, smoldering fires. PM 2.5 concentrations varied from 523 to 8357 μg m -3 and were higher on day 1. PAH weight percents (19 PAHs) were higher in slash-pile burns (0.21 ± 0.08% OC) than broadcast burns (0.07 ± 0.03% OC). The major elements were K, Cl, S, and Si. OC and EC values averaged 66 ± 7 and 2.8 ± 1.4% PM 2.5, respectively, for all burns studied, in good agreement with literature values for smoldering fires.

Characterization of PM(2.5) collected during broadcast and slash-pile prescribed burns of predominately ponderosa pine forests in northern Arizona.

PubMed

Robinson, Marin S; Zhao, Min; Zack, Lindsay; Brindley, Christine; Portz, Lillian; Quarterman, Matthew; Long, Xiufen; Herckes, Pierre

2011-04-01

Prescribed burning, in combination with mechanical thinning, is a successful method for reducing heavy fuel loads from forest floors and thereby lowering the risk of catastrophic wildfire. However, an undesirable consequence of managed fire is the production of fine particulate matter or PM(2.5) (particles ≤2.5 µm in aerodynamic diameter). Wood-smoke particulate data from 21 prescribed burns are described, including results from broadcast and slash-pile burns. All PM(2.5) samples were collected in situ on day 1 (ignition) or day 2. Samples were analyzed for mass, polycyclic aromatic hydrocarbons (PAHs), inorganic elements, organic carbon (OC), and elemental carbon (EC). Results were characteristic of low intensity, smoldering fires. PM(2.5) concentrations varied from 523 to 8357 µg m(-3) and were higher on day 1. PAH weight percents (19 PAHs) were higher in slash-pile burns (0.21 ± 0.08% OC) than broadcast burns (0.07 ± 0.03% OC). The major elements were K, Cl, S, and Si. OC and EC values averaged 66 ± 7 and 2.8 ± 1.4% PM(2.5), respectively, for all burns studied, in good agreement with literature values for smoldering fires.

Characterization of PM2.5 collected during broadcast and slash-pile prescribed burns of predominately ponderosa pine forests in northern Arizona

PubMed Central

Zhao, Min; Zack, Lindsay; Brindley, Christine; Portz, Lillian; Quarterman, Matthew; Long, Xiufen; Herckes, Pierre

2011-01-01

Prescribed burning, in combination with mechanical thinning, is a successful method for reducing heavy fuel loads from forest floors and thereby lowering the risk of catastrophic wildfire. However, an undesirable consequence of managed fire is the production of fine particulate matter or PM2.5 (particles ≤2.5 µm in aerodynamic diameter). Wood-smoke particulate data from 21 prescribed burns are described, including results from broadcast and slash-pile burns. All PM2.5 samples were collected in situ on day 1 (ignition) or day 2. Samples were analyzed for mass, polycyclic aromatic hydrocarbons (PAHs), inorganic elements, organic carbon (OC), and elemental carbon (EC). Results were characteristic of low intensity, smoldering fires. PM2.5 concentrations varied from 523 to 8357 µg m−3 and were higher on day 1. PAH weight percents (19 PAHs) were higher in slash-pile burns (0.21 ± 0.08% OC) than broadcast burns (0.07 ± 0.03% OC). The major elements were K, Cl, S, and Si. OC and EC values averaged 66 ± 7 and 2.8 ± 1.4% PM2.5, respectively, for all burns studied, in good agreement with literature values for smoldering fires. PMID:21625396

Evaluation of the SKC DPM cassette for monitoring diesel particulate matter in coal mines.

PubMed

Noll, James D; Birch, Eileen

2004-12-01

In a previous study, the efficacy of commercial and prototype impactors for sampling diesel particulate matter (DPM) in coal mines was investigated. Laboratory and field samples were collected on quartz-fiber filters and analyzed for organic and elemental carbon. Coal dust contributed a minimal amount of elemental carbon when commercial cascade impactors and prototype impactors, designed by the University of Minnesota (UMN) and the US Bureau of Mines (BOM), were used to collect submicrometer dust fractions. Other impactors were not as effective at excluding coal dust. The impactors evaluated in that study were either not commercially available or were multi-stage, expensive, and difficult to use for personal measurements. A commercial version of the BOM impactor, called the DPM Cassette, was recently introduced by SKC. Tests were conducted to evaluate the performance of the DPM Cassette for measuring diesel-source elemental carbon in the presence of coal dust. Bituminous coals from three mines in two different coal provinces were examined. The dust particle diameters were small and the coal dust contained a high percentage of carbon, thereby giving a worst-case condition for non-anthracite coal mines. Results for the DPM Cassette were essentially identical to those obtained by the BOM impactors in a previous study. At a respirable coal dust concentration of 5.46 mg m(-3), which is 3.8 times the regulatory limit, the DPM Cassette collected only 34 microg m(-3) of coal-source elemental carbon.

Characteristics of ash and particle emissions during bubbling fluidised bed combustion of three types of residual forest biomass.

PubMed

Ribeiro, João Peres; Vicente, Estela Domingos; Alves, Célia; Querol, Xavier; Amato, Fulvio; Tarelho, Luís A C

2017-04-01

Combustion of residual forest biomass (RFB) derived from eucalypt (Eucalyptus globulus), pine (Pinus pinaster) and golden wattle (Acacia longifolia) was evaluated in a pilot-scale bubbling fluidised bed reactor (BFBR). During the combustion experiments, monitoring of temperature, pressure and exhaust gas composition has been made. Ash samples were collected at several locations along the furnace and flue gas treatment devices (cyclone and bag filter) after each combustion experiment and were analysed for their unburnt carbon content and chemical composition. Total suspended particles (TSP) in the combustion flue gas were evaluated at the inlet and outlet of cyclone and baghouse filter and further analysed for organic and elemental carbon, carbonates and 57 chemical elements. High particulate matter collection efficiencies in the range of 94-99% were observed for the baghouse, while removal rates of only 1.4-17% were registered for the cyclone. Due to the sand bed, Si was the major element in bottom ashes. Fly ashes, in particular those from eucalypt combustion, were especially rich in CaO, followed by relevant amounts of SiO 2 , MgO and K 2 O. Ash characteristics varied among experiments, showing that their inorganic composition strongly depends on both the biomass composition and combustion conditions. Inorganic constituents accounted for TSP mass fractions up to 40 wt%. Elemental carbon, organic matter and carbonates contributed to TSP mass fractions in the ranges 0.58-44%, 0.79-78% and 0.01-1.7%, respectively.

Riverine Carbon and the Sedimentary Record on the Continental Shelves

DTIC Science & Technology

2005-09-30

focused on the Gulf of Lions: collecting sediment samples and carrying out elemental and stable carbon isotopic analysis . The field work was carried...organisms. For example, the predominance of nitrogen-free biomacromolecules (e.g. tannin , lignin, cellulose, cutin and suberin) over proteins (C:N ≈ 3-4...are cooperating with J. Fabres and A. Calafat (CRG Marine Geosciences) in carrying out elemental and isotopic analysis on suspended material

BC measurement activities at the U.S. Environmental Protection Agency

EPA Science Inventory

Black carbon (BC)--sometimes referred to as soot, char, or elemental carbon (EC)--is a refractory form of light-absorbing carbon produced from incomplete combustion. Accurate measurement of BC in combustion source emissions is important for understanding anthropogenic climate for...

Geochemistry of primary-carbonate bearing K-rich igneous rocks in the Awulale Mountains, western Tianshan: Implications for carbon-recycling in subduction zone

NASA Astrophysics Data System (ADS)

Yang, Wu-Bin; Niu, He-Cai; Shan, Qiang; Chen, Hua-Yong; Hollings, Pete; Li, Ning-Bo; Yan, Shuang; Zartman, Robert E.

2014-10-01

Arc magmatism plays an important role in the recycling of subducted carbon and returning it to the surface. However, the transfer mechanisms of carbon are poorly understood. In this study, the contribution of subducted carbonate-rich sediments to the genesis of the carbonate-bearing K-rich igneous rocks from western Tianshan was investigated. Four key triggers are involved, including sediments subduction, slab decarbonation, partial melting and magma segregation. The globular carbonate ocelli show C-O isotope signatures intermediate between oceanic sediments and mantle, suggesting that the carbon of the primary carbonate ocelli was derived from recycled subducted sediments in the mantle. Decarbonation of the subducted slab is regarded as the primary agent to carbonize the mantle wedge. Geochemical features indicate that the carbonate ocelli are primary, and that the parental K- and carbon-rich mafic alkaline magma was derived from partial melting of carbonated mantle wedge veined with phlogopite. Major and trace element compositions indicate that globular carbonate ocelli hosted in the Bugula K-rich igneous rocks are calcio-carbonate and formed primarily by segregation of the differentiated CO2-rich alkaline magma after crystallization fractionation. The K-rich alkaline magma, which formed from partial melting of metasomatized (i.e., phlogopite bearing) mantle wedge in the sub-arc region, is a favorable agent to transport subducted carbon back to the Earth's surface during carbon recycling in subduction zones, because of the high CO2 solubility in alkaline mafic magma. We therefore propose a model for the petrogenesis of the carbonate-bearing K-rich igneous rocks in western Tianshan, which are significant for revealing the mechanism of carbon recycling in subduction zones.

Impact of trace metals on the water structure at the calcite surface

NASA Astrophysics Data System (ADS)

Wolthers, Mariette; Di Tommaso, Devis; De Leeuw, Nora

2014-05-01

Carbonate minerals play an important role in regulating the chemistry of aquatic environments, including the oceans, aquifers, hydrothermal systems, soils and sediments. Through mineral surface processes such as dissolution, precipitation and sorption, carbonate minerals affect the biogeochemical cycles of not only the constituent elements of carbonates, such as Ca, Mg, Fe and C, but also H, P and trace elements. Surface charging of the calcite mineral-water interface, and its reactivity towards foreign ions can be quantified using a surface structural model that includes, among others, the water structure at the interface (i.e. hydrogen bridging) [1,2] in accordance with the CD-MUSIC formalism [3]. Here we will show the impact of foreign metals such as Mg and Sr on the water structure around different surface sites present in etch pits and on growth terraces at the calcite (10-14) surface. We have performed Molecular Dynamics simulations of metal-doped calcite surfaces, using different interatomic water potentials. Results show that the local environment around the structurally distinct sites differs depending on metal presence, suggesting that metal substitutions in calcite affect its reactivity. The information obtained in this study will help in improving existing macroscopic surface model for the reactivity of calcite [2] and give more general insight in mineral surface reactivity in relation to crystal composition. [1] Wolthers, Charlet, & Van Cappellen (2008). Am. J. Sci., 308, 905-941. [2] Wolthers, Di Tommaso, Du, & de Leeuw (2012). Phys. Chem. Chem. Phys. 14, 15145-15157. [3] Hiemstra and Van Riemsdijk (1996) J. Colloid Interf. Sci. 179, 488-508.

Removal of H{sub 2}S using molten carbonate at high temperature

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

Kawase, Makoto, E-mail: kawase@criepi.denken.or.jp; Otaka, Maromu

2013-12-15

Highlights: • The performance of molten carbonate for the removal of H{sub 2}S improves at higher temperatures. • The degree of H{sub 2}S removal is significantly affected by the CO{sub 2} concentration in syngas. • Addition of carbon elements, such as char and tar, decrease the negative effects of CO{sub 2}. • Continuous addition of carbon elements into molten carbonate enables continuous desulfurization. • Desulfurization using molten carbonate is suitable for gasification gas. - Abstract: Gasification is considered to be an effective process for energy conversion from various sources such as coal, biomass, and waste. Cleanup of the hot syngasmore » produced by such a process may improve the thermal efficiency of the overall gasification system. Therefore, the cleanup of hot syngas from biomass gasification using molten carbonate is investigated in bench-scale tests. Molten carbonate acts as an absorbent during desulfurization and dechlorination and as a thermal catalyst for tar cracking. In this study, the performance of molten carbonate for removing H{sub 2}S was evaluated. The temperature of the molten carbonate was set within the range from 800 to 1000 °C. It is found that the removal of H{sub 2}S is significantly affected by the concentration of CO{sub 2} in the syngas. When only a small percentage of CO{sub 2} is present, desulfurization using molten carbonate is inadequate. However, when carbon elements, such as char and tar, are continuously supplied, H{sub 2}S removal can be maintained at a high level. To confirm the performance of the molten carbonate gas-cleaning system, purified biogas was used as a fuel in power generation tests with a molten carbonate fuel cell (MCFC). The fuel cell is a high-performance sensor for detecting gaseous impurities. When purified gas from a gas-cleaning reactor was continuously supplied to the fuel cell, the cell voltage remained stable. Thus, the molten carbonate gas-cleaning reactor was found to afford good gas-cleaning performance.« less

Effects of thin-film accelerated carbonation on steel slag leaching.

PubMed

Baciocchi, R; Costa, G; Polettini, A; Pomi, R

2015-04-09

This paper discusses the effects of accelerated carbonation on the leaching behaviour of two types of stainless steel slags (electric arc furnace and argon oxygen decarburisation slag). The release of major elements and toxic metals both at the natural pH and at varying pH conditions was addressed. Geochemical modelling of the eluates was used to theoretically describe leaching and derive information about mineralogical changes induced by carbonation. Among the investigated elements, Ca and Si were most appreciably affected by carbonation. A very clear effect of carbonation on leaching was observed for silicate phases; geochemical modelling indicated that the Ca/Si ratio of Ca-controlling minerals shifted from ∼ 1 for the untreated slag to 0.5-0.67 for the carbonated samples, thus showing that the carbonation process left some residual Ca-depleted silicate phases while the extracted Ca precipitated in the form of carbonate minerals. For toxic metals the changes in leaching induced by carbonation appeared to be mainly related to the resulting pH changes, which were as high as ∼ 2 orders of magnitude upon carbonation. Depending on the specific shape of the respective solubility curves, the extent of leaching of toxic metals from the slag was differently affected by carbonation. Copyright © 2014 Elsevier B.V. All rights reserved.

Calcio-carbonatite melts and metasomatism in the mantle beneath Mt. Vulture (Southern Italy)

NASA Astrophysics Data System (ADS)

Rosatelli, Gianluigi; Wall, Frances; Stoppa, Francesco

2007-12-01

At Mt. Vulture volcano (Basilicata, Italy) calcite globules (5-150 μm) are hosted by silicate glass pools or veins cross-cutting amphibole-bearing, or more common spinel-bearing mantle xenoliths and xenocrysts. The carbonate globules are rounded or elongated and are composed of a mosaic of 2-20 μm crystals, with varying optical orientation. These features are consistent with formation from a quenched calciocarbonatite melt. Where in contact with carbonate amphibole has reacted to form fassaitic pyroxene. Some of these globules contain liquid/gaseous CO 2 bubbles and sulphide inclusions, and are pierced by quench microphenocrysts of silicate phases. The carbonate composition varies from calcite to Mg-calcite (3.8-5.0 wt.% MgO) both within the carbonate globules and from globule to globule. Trace element contents of the carbonate, determined by LAICPMS, are similar to those of carbonatites worldwide including ΣREE up to 123 ppm. The Sr-Nd isotope ratios of the xenolith carbonate are similar to the extrusive carbonatite and silicate rocks of Mt. Vulture testifying to derivation from the same mantle source. Formation of immiscibile silicate-carbonatite liquids within mantle xenoliths occurred via disequilibrium immiscibility during their exhumation.

Tracing carbonaceous sources by using particulate carbon and sulfate in precipitation in Calgary, Alberta Canada

NASA Astrophysics Data System (ADS)

Ge, C.; Stenhouse, K. J.; Du, K.; Xing, Z.; Norman, A. L.

2016-12-01

Carbonaceous matter is often the dominant contributor to Particulate Matter (PM) which has a significant influence on climate, air quality and human health. The measurement of particulate carbon in rainfall in Calgary, Alberta has not been studied. This study reports the sulfate and the first concentrations of particulate carbon (PC) in rainfall in Calgary. It traces seasonal carbonaceous sources for the purpose of understanding sources for air quality control. Precipitation samples are collected twice a day at the University of Calgary. Thermo-optical methods are used to analyze concentrations of PC, including elemental carbon (EC), primary organic carbon (POC) and secondary organic carbon (SOC). Sulfate concentrations are measured using ion chromatography. In this study, sources from long range transport and local emissions are examined. We emphasized the apportionment of OC/EC in oil and gas emissions and diurnal variations in transportation emissions. Weekly average data for dry deposition were calculated to estimate the scavenging ratio of EC/POC/SOC and ions in precipitation. The results of this study will be presented with an emphasis on the relationship of carbonaceous material and sulfate. A range of apportionment methods have been applied to examine limitations in quantifying SOC in fall.

The Diversity of Carbon in Cometary Refractory Dust Particles

NASA Technical Reports Server (NTRS)

Wooden, D. H.

2018-01-01

When comparing the dark icy surfaces of outer solar system small bodies and the composition of carbonaceous chondrites derived from dark asteroids we find a significant discrepancy in the assessed amounts of elemental carbon: up to 80% amorphous carbon is used to model the dark surfaces of Kuiper Belt Objects and Centaurs whereas at most 5% of elemental carbon is found in carbonaceous chondrites. If we presume that regimes of comet nuclei formation are analogous to disk regimes where other outer solar system ice-rich bodies formed then we can turn to comet dust to gain insights into the diversity in the concentration and forms of carbon available in the outer disk. Comet dust offers important insights into the diversity in the amounts and forms of carbon that were incorporated into aggregate dust particles in the colder parts of the protoplanetary disk out of which comet nuclei accreted. Comet nuclei are amongst the most primitive bodies because they have remained cold and unequilibrated. Comet dust particles reveal the presence of forms of elemental carbon and of soluble and insoluble organic matter, and in a great diversity of concentrations from very little, e.g., Stardust samples of comet 81P/Wild 2, to 80% by volume for Ultra Carbonaceous Antarctic Micro Meteorites (UCAMMs). Cometary outbursts and/or jet activity also demonstrate variations in the concentration of carbon in the grains at different grain sizes within a single comet. We review the diversity of carbon-bearing dust grains in cometary samples, flyby measurements and deduced from remote-sensing to enrich the discussion about the diversity of carbonaceous matter available in the outer ice-rich disk at the time of comet nuclei formation.

Fundamental aspects of recoupled pair bonds. I. Recoupled pair bonds in carbon and sulfur monofluoride

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

Dunning, Thom H., E-mail: thdjr@uw.edu; Xu, Lu T.; Takeshita, Tyler Y.

2015-01-21

The number of singly occupied orbitals in the ground-state atomic configuration of an element defines its nominal valence. For carbon and sulfur, with two singly occupied orbitals in their {sup 3}P ground states, the nominal valence is two. However, in both cases, it is possible to form more bonds than indicated by the nominal valence—up to four bonds for carbon and six bonds for sulfur. In carbon, the electrons in the 2s lone pair can participate in bonding, and in sulfur the electrons in both the 3p and 3s lone pairs can participate. Carbon 2s and sulfur 3p recoupled pairmore » bonds are the basis for the tetravalence of carbon and sulfur, and 3s recoupled pair bonds enable sulfur to be hexavalent. In this paper, we report generalized valence bond as well as more accurate calculations on the a{sup 4}Σ{sup −} states of CF and SF, which are archetypal examples of molecules that possess recoupled pair bonds. These calculations provide insights into the fundamental nature of recoupled pair bonds and illustrate the key differences between recoupled pair bonds formed with the 2s lone pair of carbon, as a representative of the early p-block elements, and recoupled pair bonds formed with the 3p lone pair of sulfur, as a representative of the late p-block elements.« less

Microstructural design in low alloy steels

NASA Technical Reports Server (NTRS)

Honeycombe, R. W. K.

1982-01-01

The evolution of microalloyed steels from plain carbon steels is examined with emphasis on grain size control by use of Nb, Ti and V additions and by the application of controlled rolling. The structural changes during controlled rolling are described as well as the influence of alloying elements on these changes, and on the final microstructure. The achievement of high strength and toughness is discussed including the role of inclusions.

FUEL COMPOSITION FOR NUCLEAR REACTORS

DOEpatents

Andersen, J.C.

1963-08-01

A process for making refractory nuclear fuel elements involves heating uranium and silicon powders in an inert atmosphere to 1600 to 1800 deg C to form USi/sub 3/; adding silicon carbide, carbon, 15% by weight of nickel and aluminum, and possibly also molybdenum and silicon powders; shaping the mixture; and heating to 1700 to 2050 deg C again in an inert atmosphere. Information on obtaining specific compositions is included. (AEC)

Recovery and reuse of sludge from active and passive treatment of mine drainage-impacted waters: a review.

PubMed

Rakotonimaro, Tsiverihasina V; Neculita, Carmen Mihaela; Bussière, Bruno; Benzaazoua, Mostafa; Zagury, Gérald J

2017-01-01

The treatment of mine drainage-impacted waters generates considerable amounts of sludge, which raises several concerns, such as storage and disposal, stability, and potential social and environmental impacts. To alleviate the storage and management costs, as well as to give the mine sludge a second life, recovery and reuse have recently become interesting options. In this review, different recovery and reuse options of sludge originating from active and passive treatment of mine drainage are identified and thoroughly discussed, based on available laboratory and field studies. The most valuable products presently recovered from the mine sludge are the iron oxy-hydroxides (ochre). Other by-products include metals, elemental sulfur, and calcium carbonate. Mine sludge reuse includes the removal of contaminants, such as As, P, dye, and rare earth elements. Mine sludge can also be reused as stabilizer for contaminated soil, as fertilizer in agriculture/horticulture, as substitute material in construction, as cover over tailings for acid mine drainage prevention and control, as material to sequester carbon dioxide, and in cement and pigment industries. The review also stresses out some of the current challenges and research needs. Finally, in order to move forward, studies are needed to better estimate the contribution of sludge recovery/reuse to the overall costs of mine water treatment.

Novel Estimation of the Humification Degree of Soil Organic Matter by Laser-Induced Breakdown Spectroscopy (LIBS) Compared to Laser-Induced Fluorescence Spectroscopy (LIFS)

NASA Astrophysics Data System (ADS)

Ferreira, Edilene; Ferreira, Ednaldo; Villas-Boas, Paulino; Senesi, Giorgio; Carvalho, Camila; Romano, Renan; Martin-Neto, Ladislau; Milori, Debora

2014-05-01

Soil organic matter (SOM) constitutes an important reservoir of terrestrial carbon and can be considered an alternative for atmospheric carbon storage, contributing to global warming mitigation. Soil management can favor atmospheric carbon incorporation into SOM or its release from SOM to atmosphere. Thus, the evaluation of the humification degree (HD), which is an indication of the recalcitrance of SOM, can provide an estimation of the capacity of carbon sequestration in soils under various managements. The HD of SOM can be estimated by using various analytical techniques including fluorescence spectroscopy. In the present work, the potential of Laser-Induced Breakdown Spectroscopy (LIBS) to estimate the HD of SOM was evaluated for the first time. In a LIBS experiment a high-energy laser pulse irradiates the sample and the energy absorbed by the sample causes a local heating of the material that results in its evaporation or sublimation. The high temperature of the ablated material generates a small plasma plume and, as a result of the plasma temperature, the ablated material breaks down into excited atomic and ionic species. During the plasma cooling, the excited species return to their lower energy state emitting electromagnetic radiation at characteristic wavelengths. In a LIBS spectrum the measurement of the characteristic emission wavelengths provides qualitative information about the elemental composition of the sample, whereas the intensities of the signals can be used for quantitative determinations. The LIBS potential for the analysis of organic compounds has been explored recently by using the emission lines of elements that are commonly present in organic compounds, such as the predominant C, H, P, O and N. LIBS elemental emissions were correlated to fluorescence emissions determined by Laser-Induced Fluorescence Spectroscopy (LIFS), which was considered as the reference technique. The HD of SOM determined by LIBS showed a strong correlation to that determined by LIFS, suggesting a great potential of LIBS for this novel application.

Magnetoexcitons and Faraday rotation in single-walled carbon nanotubes and graphene nanoribbons

NASA Astrophysics Data System (ADS)

Have, Jonas; Pedersen, Thomas G.

2018-03-01

The magneto-optical response of single-walled carbon nanotubes (CNTs) and graphene nanoribbons (GNRs) is studied theoretically, including excitonic effects. Both diagonal and nondiagonal response functions are obtained and employed to compute Faraday rotation spectra. For single-walled CNTs in a parallel field, the results show field-dependent splitting of the exciton absorption peaks caused by brightening a dark exciton state. Similarly, for GNRs in a perpendicular magnetic field, we observe a field-dependent shift of the exciton peaks and the emergence of an absorption peak above the energy gap. Results show that excitonic effects play a significant role in the optical response of both materials, particularly for the off-diagonal tensor elements.

Characterization of Three Carbon- and Nitrogen-Rich Particles from Comet 81P/WILD

NASA Technical Reports Server (NTRS)

Gallien, J.-P.; Khodja, H.; Herzog, G. F.; Taylor, S.; Koepsell, E.; Daghlian, C. P.; Flynn, G. J.; Sitnitsky, I.; Lanzirotti, A.; Sutton, S. R.;

Catchment-scale redistribution of lithogenic solutes and black carbon over three years following wildfire in the Jemez Mountains, New Mexico, USA

NASA Astrophysics Data System (ADS)

Pohlmann, M. A.; Root, R.; Abrell, L.; Schwartz, C. J.; Chorover, J.

2017-12-01

Wildfire represents a disturbance that is becoming more prevalent as climate shifts to hotter and drier conditions in the southwestern US. It has profound and potentially long-term effects on the physical, chemical and microbiological properties of soil, including immediate surface deposition of lithogenic elements and incompletely combusted organic matter (i.e., black carbon or BC) previously held in biomass. The long residence time of BC mitigates oxidative release of carbon to the atmosphere and thus has implications for long-term climate forcing. Immediately following the 2013 Thompson Ridge wildfire in the Jemez River Basin Critical Zone Observatory, we sampled 22 soil profiles across a zero order basin at finely resolved depth intervals to 40 cm. Samples were collected again 12 and 24 months following the fire to assess redistribution of solutes and BC in the two years following fire. Water extractable anions, cations and carbon were measured for each sample and maps were generated by geostatistical interpolation. Additionally, the benzene polycarboxylic acid (BPCA) molecular marker method was employed for a selection of samples to quantify and characterize the BC content of the existing soil organic carbon pool as a function of landscape position and time. The `pulsed' deposition of water-soluble ions and BC followed pre-fire vegetation structure as indicated by solution chemistry data for years one and two displaying elevated solute concentrations in surface depths proximal to dense vegetation. Vertical and lateral redistribution of the water extractable elements and BC were consistent with wetting front propagation and topographic trends (driven by erosion, overland flow and lateral subsurface flow). BC depth profiles indicate vertical infiltration and lateral transport with burial, the latter associated with surface erosion of sediment, as mechanisms for redistribution.

Black Carbon And Co-Pollutants Emissions And Energy Efficiency From Bricks Production In Guanajuato, Mexico

NASA Astrophysics Data System (ADS)

Molina, L. T.; Zavala, M.; Maiz, P.; Monsivais, I.; Chow, J.; Munguia, J.

2013-12-01

In many parts of the world, small-scale traditional brick kilns are a notorious informal sector source of urban air pollution. Many are both inefficient and burn highly polluting fuels that emit significant levels of black carbon and other pollutants into local communities and to the atmosphere, resulting in severe health and environmental impacts. It is estimated that there are nearly 20,000 traditional brick kilns in Mexico, in which bricks are still produced as they have been for centuries. They are made by hand, dried in the sun, and generally fired in small, one chamber kilns that use various types of fuels, including plastic refuse, used tires, manure, wood scrap, and used motor oil. Three brick kilns, two traditional kilns and an improved kiln (MK2), were sampled as part of the SLCFs-Mexico campaign in Guanajuato, Mexico during March of 2013. The concept of the MK-2 involves covering the kiln with a dome and channeling the output of an active kiln through a second, identical loaded kiln for its additional filtration of the effluents. The results of energy efficiency and carbon mass balance calculations are presented for comparing the production efficiency and carbon emissions from the sampled kilns. Measurements included PM2.5 mass with quartz filters and temporally-resolved elemental carbon and organic carbon composition obtained using thermo-optical methods. The carbon emissions obtained with the mass balance method are compared with concurrent, high- time resolution, emissions measurements obtained using the Aerodyne mobile laboratory employing the tracer method (see abstract by Fortner et al.)

Carbon Nanotube Based Flexible Supercapacitors

DTIC Science & Technology

2011-04-01

Carbon Nanotube Based Flexible Supercapacitors by Christopher M. Anton and Matthew H. Ervin ARL-TR-5522 April 2011...Carbon Nanotube Based Flexible Supercapacitors Christopher M. Anton and Matthew H. Ervin Sensors and Electron Devices Directorate, ARL...September 2010 4. TITLE AND SUBTITLE Carbon Nanotube Based Flexible Supercapacitors 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT

OPTIMIZATION OF THERMAL OPTICAL ANALYSIS FOR THE MEASUREMENT OF BLACK CARBON IN REGIONAL PM2.5: A CHEMOMETRIC APPROACH

EPA Science Inventory

Thermal-optical analysis (TOA) is the principal method of the U.S. EPA's National Air Monitoring System for determining refractory carbon from combustion, or elemental carbon (EC), in particulate matter <2.5 µm (PM_2.5). To isolate and quantify EC from organic carbon (...

Control of carbon balance in a silicon smelting furnace

DOEpatents

Dosaj, Vishu D.; Haines, Cathryn M.; May, James B.; Oleson, John D.

1992-12-29

The present invention is a process for the carbothermic reduction of silicon dioxide to form elemental silicon. Carbon balance of the process is assessed by measuring the amount of carbon monoxide evolved in offgas exiting the furnace. A ratio of the amount of carbon monoxide evolved and the amount of silicon dioxide added to the furnace is determined. Based on this ratio, the carbon balance of the furnace can be determined and carbon feed can be adjusted to maintain the furnace in carbon balance.

Final Report - "CO2 Sequestration in Cell Biomass of Chlorobium Thiosulfatophilum"

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

James L. Gaddy, PhD; Ching-Whan Ko, PhD

2009-05-04

World carbon dioxide emissions from the combustion of fossil fuels have increased at a rate of about 3 percent per year during the last 40 years to over 24 billion tons today. While a number of methods have been proposed and are under study for dealing with the carbon dioxide problem, all have advantages as well as disadvantages which limit their application. The anaerobic bacterium Chlorobium thiosulfatophilum uses hydrogen sulfide and carbon dioxide to produce elemental sulfur and cell biomass. The overall objective of this project is to develop a commercial process for the biological sequestration of carbon dioxide andmore » simultaneous conversion of hydrogen sulfide to elemental sulfur. The Phase I study successfully demonstrated the technical feasibility of utilizing this bacterium for carbon dioxide sequestration and hydrogen sulfide conversion to elemental sulfur by utilizing the bacterium in continuous reactor studies. Phase II studies involved an advanced research and development to develop the engineering and scale-up parameters for commercialization of the technology. Tasks include culture isolation and optimization studies, further continuous reactor studies, light delivery systems, high pressure studies, process scale-up, a market analysis and economic projections. A number of anaerobic and aerobic microorgansims, both non-photosynthetic and photosynthetic, were examined to find those with the fastest rates for detailed study to continuous culture experiments. C. thiosulfatophilum was selected for study to anaerobically produce sulfur and Thiomicrospira crunogena waws selected for study to produce sulfate non-photosynthetically. Optimal conditions for growth, H2S and CO2 comparison, supplying light and separating sulfur were defined. The design and economic projections show that light supply for photosynthetic reactions is far too expensive, even when solar systems are considered. However, the aerobic non-photosynthetic reaction to produce sulfate with T. crunogena produces a reasonable return when treating a sour gas stream of 120 million SCFD containing 2.5 percent H2S. In this case, the primary source of revenue is from desulfurization of the gas stream. While the technology has significant application in sequestering carbon dioxide in cell biomass or single cell proten (SCP), perhaps the most immediate application is in desulfurizing LGNG or other gas streams. This biological approach is a viable economical alternative to existing hydrogen sulfide removal technology, and is not sensitive to the presence of hydrocarbons which act as catalyst poisons.« less

Influence of Secondary Cooling Mode on Solidification Structure and Macro-segregation Behavior for High-carbon Continuous Casting Bloom

NASA Astrophysics Data System (ADS)

Dou, Kun; Yang, Zhenguo; Liu, Qing; Huang, Yunhua; Dong, Hongbiao

2017-07-01

A cellular automaton-finite element coupling model for high-carbon continuously cast bloom of GCr15 steel is established to simulate the solidification structure and to investigate the influence of different secondary cooling modes on characteristic parameters such as equiaxed crystal ratio, grain size and secondary dendrite arm spacing, in which the effect of phase transformation and electromagnetic stirring is taken into consideration. On this basis, evolution of carbon macro-segregation for GCr15 steel bloom is researched correspondingly via industrial tests. Based on above analysis, the relationship among secondary cooling modes, characteristic parameters for solidification structure as well as carbon macro-segregation is illustrated to obtain optimum secondary cooling strategy and alleviate carbon macro-segregation degree for GCr15 steel bloom in continuous casting process. The evaluating method for element macro-segregation is applicable in various steel types.

Foil Strain Gauges Using Piezoresistive Carbon Nanotube Yarn: Fabrication and Calibration

PubMed Central

Góngora-Rubio, Mário R.; Kiyono, César Y.; Mello, Luis A. M.; Cardoso, Valtemar F.; Rosa, Reinaldo L. S.; Kuebler, Derek A.; Brodeur, Grace E.; Alotaibi, Amani H.; Coene, Marisa P.; Coene, Lauren M.; Jean, Elizabeth; Santiago, Rafael C.; Oliveira, Francisco H. A.; Rangel, Ricardo; Thomas, Gilles P.; Belay, Kalayu; da Silva, Luciana W.; Moura, Rafael T.; Seabra, Antonio C.; Silva, Emílio C. N.

2018-01-01

Carbon nanotube yarns are micron-scale fibers comprised by tens of thousands of carbon nanotubes in their cross section and exhibiting piezoresistive characteristics that can be tapped to sense strain. This paper presents the details of novel foil strain gauge sensor configurations comprising carbon nanotube yarn as the piezoresistive sensing element. The foil strain gauge sensors are designed using the results of parametric studies that maximize the sensitivity of the sensors to mechanical loading. The fabrication details of the strain gauge sensors that exhibit the highest sensitivity, based on the modeling results, are described including the materials and procedures used in the first prototypes. Details of the calibration of the foil strain gauge sensors are also provided and discussed in the context of their electromechanical characterization when bonded to metallic specimens. This characterization included studying their response under monotonic and cyclic mechanical loading. It was shown that these foil strain gauge sensors comprising carbon nanotube yarn are sensitive enough to capture strain and can replicate the loading and unloading cycles. It was also observed that the loading rate affects their piezoresistive response and that the gauge factors were all above one order of magnitude higher than those of typical metallic foil strain gauges. Based on these calibration results on the initial sensor configurations, new foil strain gauge configurations will be designed and fabricated, to increase the strain gauge factors even more. PMID:29401745

Permeable reactive barrier of surface hydrophobic granular activated carbon coupled with elemental iron for the removal of 2,4-dichlorophenol in water.

PubMed

Yang, Ji; Cao, Limei; Guo, Rui; Jia, Jinping

2010-12-15

Granular activated carbon was modified with dimethyl dichlorosilane to improve its surface hydrophobicity, and therefore to improve the performance of permeable reactive barrier constructed with the modified granular activated carbon and elemental iron. X-ray photoelectron spectroscopy shows that the surface silicon concentration of the modified granular activated carbon is higher than that of the original one, leading to the increased surface hydrophobicity. Although the specific surface area decreased from 895 to 835 m(2)g(-1), the modified granular activated carbon could adsorb 20% more 2,4-dichlorophenol than the original one did in water. It is also proven that the permeable reactive barrier with the modified granular activated carbon is more efficient at 2,4-dichlorophenol dechlorination, in which process 2,4-dichlorophenol is transformed to 2-chlorophenol or 4-chlorophenol then to phenol, or to phenol directly. Copyright © 2010 Elsevier B.V. All rights reserved.

Adsorption of oils, heavy metals and dyes by recovered carbon powder from spent pot liner of aluminum smelter plant.

PubMed

Mazumder, B; Devi, Sasmita Rani

2008-07-01

Aluminum smelter plants employ Hall-Heroult electrolysis cells for electrolysis of molten cryolite to recover aluminum metal by electrolysis. These cells use carbon cathode blocks as a lining material inside. At the end of service life of the cells, pot lines are discarded and new carbon blocks are laid for fresh charging. These used carbon cathode blocks, known as spent pot liners, are heavily infested with toxic elements such as fluoride, cyanide, alkali, etc. Therefore, their disposal in open field poses great environmental risk. A simple process has been developed for decontamination of these spent pot liners and to recover its carbon value. The experiments indicated that this carbon, in the form of fine powder (around 20 micron in size) can absorb toxic elements like heavy metals, dyes, oils, etc. to a great extent and thus can be used for mitigating environmental pollution occuring due to various toxic wastes.

Normal and outlying populations of the Milky Way stellar halo at [Fe/H] <–2

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

Cohen, Judith G.; Christlieb, Norbert; Thompson, Ian

2013-11-20

From detailed abundance analysis of >100 Hamburg/ESO candidate extremely metal-poor (EMP) stars we find 45 with [Fe/H] < –3.0 dex. We identify a heretofore unidentified group: Ca-deficient stars with sub-solar [Ca/Fe] ratios and the lowest neutron-capture abundances; the Ca-deficient group comprises ∼10% of the sample, excluding Carbon stars. Our radial velocity distribution shows that the carbon-enhanced stars with no s-process enhancements, CEMP-no, and which do not show C{sub 2} bands are not preferentially binary systems. Ignoring Carbon stars, approximately 15% of our sample are strong (≥5σ) outliers in one or more elements between Mg and Ni; this rises to ∼19%more » if very strong (≥10σ) outliers for Sr and Ba are included. Examples include: HE0305–0554 with the lowest [Ba/H] known; HE1012–1540 and HE2323–0256, two (non-velocity variable) C-rich stars with very strong [Mg,Al/Fe] enhancements; and HE1226–1149, an extremely r-process rich star.« less

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

Prahl, F.G.; Sparrow, M.A.; Eversmeyer, B.

Elemental and stable carbon isotopic compositions and biomarker concentrations were determined in sediments from the Columbia River basin and the Washington margin in order to evaluate geochemical approaches for quantifying terrestrial organic matter in marine sediments. The biomarkers include: an homologous series of long-chain n-alkanes derived from the surface waxes of higher plants; phenolic and hydroxyalkanoic compounds produced by CuO oxidation of two major vascular plant biopolymers, lignin and cutin. All marine sediments, including samples collected from the most remote sites in Cascadia Basin, showed organic geochemical evidence for the presence of terrestrial organic carbon. Using endmember values for themore » various biomarkers determined empirically by two independent means, the authors estimate that the terrestrial contribution to the Washington margin is [approximately] 60% for shelf sediments, [approximately] 30% for slope sediments, and decreases further to [le] 15% in basin sediments. Results from the same geochemical measurements made with depth in gravity core 6705-7 from Cascadia Seachannel suggest that this approach to assess terrestrial organic carbon contributions to contemporary deposits on the Washington margin can be applied to the study of sediments depositing in this region since the last glacial period.« less

Reservoir-Scale Biological Community Response to Trace Element Additions in a Northern Montana Oil Field

NASA Astrophysics Data System (ADS)

Connors, D. E.; Bradfish, J.; DeBruyn, R. P.; Zemetra, J.; Mitchell, H.

2017-12-01

In subsurface oil bearing formations, microbial growth and metabolism is restricted due to a lack of elements other than carbon, hydrogen, and oxygen required for cell structure and as cofactors. A chemical treatment that adds these elements back into the formation was deployed into an oil reservoir in Northern Montana, with the intent of increasing biogenic methane generation. Samples of water from producing wells in the reservoir were collected anaerobically, and analyzed for geochemical content, and cells from the water were collected and analyzed via 16S rRNA gene DNA sequencing to determine the makeup of the microbial community over the course of twelve months of treatment, and for two years after. Prior to chemical treatment, this reservoir was depleted in elements required for enzyme co-factors in the methanogenesis metabolic pathway (Co, Mo, Ni, W, Zn) as well as nitrogen and phosphorus. Most the microbial community was composed of chemoheterotrophic bacteria associated with the biodegradation of large carbon molecules, with a small community of acetoclastic methanogens. During and after additions of the depleted elements, the metabolism of the community in the reservoir shifted towards chemoautotrophs and hydrogenotrophic methanogens, and the cell density increased. After treatment was ended, cell counts stabilized at a new equilibrium concentration, and the autotrophic metabolism was maintained. The pre-treatment community was dependent on energy input from solubilized oil molecules, whereas the post-treatment community more effectively utilized dissolved organics and carbon dioxide as carbon sources for fixation and respiration. This study demonstrates the capability of microbial communities to rapidly reorganize in the environment when provided with an influx of the elements required for growth and metabolism.

The origin of black carbon on speleothems in tourist caves in South Korea: Chemical characterization and source discrimination by radiocarbon measurement

NASA Astrophysics Data System (ADS)

Chang, Sae Jung; Jeong, Gi Young; Kim, Soo Jin

Since the Gosu, Ondal, and Sungryu karst caves in South Korea became open to the public several decades ago, the surface of their speleothems has been turning black due to pollutants. The black pollutant is concentrated at the surface of speleothems, and the surface black layer is 0.1 to several millimeters thick. Elemental measurements of three bulk, acid-dissolved and oxidized fractions of the surface black layer show that the black pigment is a black carbon. The black carbon correlates positively with sulfates, nitrates, manganese, and lead, which are typical tracers of industrial and urban emissions. The 14C-measurement of the black carbon, using accelerator mass spectrometry, shows that the black carbon was derived from both fossil-fuel combustion and biomass burning in roughly equal amounts, evidenced by fC value ranging from 0.340 to 0.592 (<±0.004, 1 σ). Therefore, protection of speleothems from black coloration requires control of anthropogenic black carbons carried by visitors. Suitable measures might include closure of caves, air cleaning of visitors and regulation of visitor numbers. The application of radiocarbon measurement of black carbon suggests that the fC is a valuable proxy for tracing the blackening phenomenon of natural and cultural heritage sites such as caves.

Selection criteria for oxidation method in total organic carbon measurement.

PubMed

Yoon, GeunSeok; Park, Sang-Min; Yang, Heuiwon; Tsang, Daniel C W; Alessi, Daniel S; Baek, Kitae

2018-05-01

During the measurement of total organic carbon (TOC), dissolved organic carbon is converted into CO 2 by using high temperature combustion (HTC) or wet chemical oxidation (WCO). However, the criteria for selecting the oxidation methods are not clear. In this study, the chemical structures of organic material were considered as a key factor to select the oxidation method used. Most non-degradable organic compounds showed a similar oxidation efficiency in both methods, including natural organic compounds, dyes, and pharmaceuticals, and thus both methods are appropriate to measure TOC in waters containing these compounds. However, only a fraction of the carbon in the halogenated compounds (perfluorooctanoic acid and trifluoroacetic acid) were oxidized using WCO, resulting in measured TOC values that are considerably lower than those determined by HTC. This result is likely due to the electronegativity of halogen elements which inhibits the approach of electron-rich sulfate radicals in the WCO, and the higher bond strength of carbon-halogen pairs as compared to carbon-hydrogen bonds, which results in a lower degree of oxidation of the compounds. Our results indicate that WCO could be used to oxidize most organic compounds, but may not be appropriate to quantify TOC in organic carbon pools that contain certain halogenated compounds. Copyright © 2018 Elsevier Ltd. All rights reserved.

Black carbon in aerosol during BIBLE B

NASA Astrophysics Data System (ADS)

Liley, J. Ben; Baumgardner, D.; Kondo, Y.; Kita, K.; Blake, D. R.; Koike, M.; Machida, T.; Takegawa, N.; Kawakami, S.; Shirai, T.; Ogawa, T.

2003-02-01

The Biomass Burning and Lightning Experiment (BIBLE) A and B campaigns over the tropical western Pacific during springtime deployed a Gulfstream-II aircraft with systems to measure ozone and numerous precursor species. Aerosol measuring systems included a MASP optical particle counter, a condensation nucleus (CN) counter, and an absorption spectrometer for black carbon. Aerosol volume was very low in the middle and upper troposphere during both campaigns, and during BIBLE A, there was little aerosol enhancement in the boundary layer away from urban areas. In BIBLE B, there was marked aerosol enhancement in the lowest 3 km of the atmosphere. Mixing ratios of CN in cloud-free conditions in the upper troposphere were in general higher than in the boundary layer, indicating new particle formation from gaseous precursors. High concentrations of black carbon were observed during BIBLE B, with mass loadings up to 40 μg m-3 representing as much as one quarter of total aerosol mass. Strong correlations with hydrocarbon enhancement allow the determination of a black carbon emission ratio for the fires at that time. Expressed as elemental carbon, it is about 0.5% of carbon dioxide and 6% of carbon monoxide emissions from the same fires, comparable to methane production, and greater than that of other hydrocarbons.

Black carbon in aerosol during BIBLE B

NASA Astrophysics Data System (ADS)

Liley, J. Ben; Baumgardner, D.; Kondo, Y.; Kita, K.; Blake, D. R.; Koike, M.; Machida, T.; Takegawa, N.; Kawakami, S.; Shirai, T.; Ogawa, T.

2002-02-01

The Biomass Burning and Lightning Experiment (BIBLE) A and B campaigns over the tropical western Pacific during springtime deployed a Gulfstream-II aircraft with systems to measure ozone and numerous precursor species. Aerosol measuring systems included a MASP optical particle counter, a condensation nucleus (CN) counter, and an absorption spectrometer for black carbon. Aerosol volume was very low in the middle and upper troposphere during both campaigns, and during BIBLE A, there was little aerosol enhancement in the boundary layer away from urban areas. In BIBLE B, there was marked aerosol enhancement in the lowest 3 km of the atmosphere. Mixing ratios of CN in cloud-free conditions in the upper troposphere were in general higher than in the boundary layer, indicating new particle formation from gaseous precursors. High concentrations of black carbon were observed during BIBLE B, with mass loadings up to 40 μg m-3 representing as much as one quarter of total aerosol mass. Strong correlations with hydrocarbon enhancement allow the determination of a black carbon emission ratio for the fires at that time. Expressed as elemental carbon, it is about 0.5% of carbon dioxide and 6% of carbon monoxide emissions from the same fires, comparable to methane production, and greater than that of other hydrocarbons.

Multiscale Analysis of Delamination of Carbon Fiber-Epoxy Laminates with Carbon Nanotubes

NASA Technical Reports Server (NTRS)

Riddick, Jaret C.; Frankland, SJV; Gates, TS

2006-01-01

A multi-scale analysis is presented to parametrically describe the Mode I delamination of a carbon fiber/epoxy laminate. In the midplane of the laminate, carbon nanotubes are included for the purposes of selectively enhancing the fracture toughness of the laminate. To analyze carbon fiber epoxy carbon nanotube laminate, the multi-scale methodology presented here links a series of parameterizations taken at various length scales ranging from the atomistic through the micromechanical to the structural level. At the atomistic scale molecular dynamics simulations are performed in conjunction with an equivalent continuum approach to develop constitutive properties for representative volume elements of the molecular structure of components of the laminate. The molecular-level constitutive results are then used in the Mori-Tanaka micromechanics to develop bulk properties for the epoxy-carbon nanotube matrix system. In order to demonstrate a possible application of this multi-scale methodology, a double cantilever beam specimen is modeled. An existing analysis is employed which uses discrete springs to model the fiber bridging affect during delamination propagation. In the absence of empirical data or a damage mechanics model describing the effect of CNTs on fracture toughness, several tractions laws are postulated, linking CNT volume fraction to fiber bridging in a DCB specimen. Results from this demonstration are presented in terms of DCB specimen load-displacement responses.

Quality of poultry litter-derived granular activated carbon.

PubMed

Qiu, Guannan; Guo, Mingxin

2010-01-01

Utilization of poultry litter as a source material for generating activated carbon is a value-added and environmentally beneficial approach to recycling organic waste. In this study, the overall quality of poultry litter-derived granular activated carbon was systematically evaluated based on its various physical and chemical properties. Granular activated carbon generated from pelletized poultry litter following a typical steam-activation procedure possessed numerous micropores in the matrix. The product exhibited a mean particle diameter of 2.59 mm, an apparent density of 0.45 g cm(-3), a ball-pan hardness of 91.0, an iodine number of 454 mg g(-1), and a BET surface area of 403 m(2) g(-1). It contained high ash, nitrogen, phosphorus contents and the trace elements Cu, Zn, and As. Most of the nutrients and toxic elements were solidified and solution-unextractable. In general, poultry litter-based activated carbon demonstrated overall quality comparable to that of low-grade commercial activated carbon derived from coconut shell and bituminous coal. It is promising to use poultry litter as a feedstock to manufacture activated carbon for wastewater treatment.

Electric dipole moment function of the X1 Sigma/+/ state of CO - Vibration-rotation matrix elements for transitions of gas laser and astrophysical interest

NASA Technical Reports Server (NTRS)

Chackerian, C., Jr.

1976-01-01

The electric dipole moment function of the ground electronic state of carbon monoxide has been determined by combining numerical solutions of the radial Schrodinger equation with absolute intensity data of vibration-rotation bands. The derived dipole moment function is used to calculate matrix elements of interest to stellar astronomy and of importance in the carbon monoxide laser.

Environmental controls on the elemental composition of a Southern Hemisphere strain of the coccolithophore Emiliania huxleyi

NASA Astrophysics Data System (ADS)

Feng, Yuanyuan; Roleda, Michael Y.; Armstrong, Evelyn; Law, Cliff S.; Boyd, Philip W.; Hurd, Catriona L.

2018-01-01

A series of semi-continuous incubation experiments were conducted with the coccolithophore Emiliania huxleyi strain NIWA1108 (Southern Ocean isolate) to examine the effects of five environmental drivers (nitrate and phosphate concentrations, irradiance, temperature, and partial pressure of CO2 (pCO2)) on both the physiological rates and elemental composition of the coccolithophore. Here, we report the alteration of the elemental composition of E. huxleyi in response to the changes in these environmental drivers. A series of dose-response curves for the cellular elemental composition of E. huxleyi were fitted for each of the five drivers across an environmentally representative gradient. The importance of each driver in regulating the elemental composition of E. huxleyi was ranked using a semi-quantitative approach. The percentage variations in elemental composition arising from the change in each driver between present-day and model-projected conditions for the year 2100 were calculated. Temperature was the most important driver controlling both cellular particulate organic and inorganic carbon content, whereas nutrient concentrations were the most important regulator of cellular particulate nitrogen and phosphorus of E. huxleyi. In contrast, elevated pCO2 had the greatest influence on cellular particulate inorganic carbon to organic carbon ratio, resulting in a decrease in the ratio. Our results indicate that the different environmental drivers play specific roles in regulating the elemental composition of E. huxleyi with wide-reaching implications for coccolithophore-related marine biogeochemical cycles, as a consequence of the regulation of E. huxleyi physiological processes.

Chemical characterization of biomass fuel smoke particles of rural kitchens of South Asia

NASA Astrophysics Data System (ADS)

Deka, Pratibha; Hoque, Raza Rafiqul

2015-05-01

Biomass fuel smoke particles (BFSPs) of rural kitchens collected during dry and wet seasons were characterized for elements, anions and carbon. The BFSPs of kitchens using varied biomass fuel types viz. cow dung stick, mixed biomass, cow-dung stick-mixed biomass and sugarcane bagasse were chosen for the study. The BFSPs from cow dung fuel stick showed higher levels of elements, anions and particulate carbon than other BFSPs. Calcium, K, Fe and Mg were the major elements found in all BFSPs, which did not vary much between the seasons. Sulphate was found to be the dominant anion present in all BFSPs followed by Clˉ and PO43-. Seasonal variation was pronounced in the case of abundance of anions and particulate carbon. The ratio OC/EC, often used as source signature of biomass burning, was found to be within 1.89-7.41 and 1.72-6.19 during dry and wet seasons respectively.

Risk analysis approach. [of carbon fiber release

NASA Technical Reports Server (NTRS)

Huston, R. J.

1979-01-01

The assessment of the carbon fiber hazard is outlined. Program objectives, requirements of the risk analysis, and elements associated with the physical phenomena of the accidental release are described.

Diesel exhaust exposures in port workers.

PubMed

Debia, Maximilien; Neesham-Grenon, Eve; Mudaheranwa, Oliver C; Ragettli, Martina S

2016-07-01

Exposure to diesel engine exhaust has been linked to increased cancer risk and cardiopulmonary diseases. Diesel exhaust is a complex mixture of chemical substances, including a particulate fraction mainly composed of ultrafine particles, resulting from the incomplete combustion of fuel. Diesel trucks are known to be an important source of diesel-related air pollution, and areas with heavy truck traffic are associated with higher air pollution levels and increased public health problems. Several indicators have been proposed as surrogates for estimating exposures to diesel exhaust but very few studies have focused specifically on monitoring the ultrafine fraction through the measurement of particle number concentrations. The aim of this study is to assess occupational exposures of gate controllers at the port of Montreal, Canada, to diesel engine emissions from container trucks by measuring several surrogates through a multimetric approach which includes the assessment of both mass and number concentrations and the use of direct reading devices. A 10-day measurement campaign was carried out at two terminal checkpoints at the port of Montreal. Respirable elemental and organic carbon, PM1, PM2.5, PMresp (PM4), PM10, PMtot (inhalable fraction), particle number concentrations, particle size distributions, and gas concentrations (NO2, NO, CO) were monitored. Gate controllers were exposed to concentrations of contaminants associated with diesel engine exhaust (elemental carbon GM = 1.6 µg/m(3); GSD = 1.6) well below recommended occupational exposure limits. Average daily particle number concentrations ranged from 16,544-67,314 particles/cm³ (GM = 32,710 particles/cm³; GSD = 1.6). Significant Pearson correlation coefficients were found between daily elemental carbon, PM fractions and particle number concentrations, as well as between total carbon, PM fractions and particle number concentrations. Significant correlation coefficients were found between particle number concentrations and the number of trucks and wind speed (R(2) = 0.432; p < 0.01). The presence of trucks with cooling systems and older trucks with older exhaust systems was associated with peak concentrations on the direct reading instruments. The results highlight the relevance of direct reading instruments in helping to identify sources of exposure and suggest that monitoring particle number concentrations improves understanding of workers' exposures to diesel exhaust. This study, by quantifying workers' exposure levels through a multimetric approach, contributes to the further understanding of occupational exposures to diesel engine exhaust.

Reinforced Carbon Carbon (RCC) oxidation resistant material samples - Baseline coated, and baseline coated with tetraethyl orthosilicate (TEOS) impregnation

NASA Technical Reports Server (NTRS)

Gantz, E. E.

1977-01-01

Reinforced carbon-carbon material specimens were machined from 19 and 33 ply flat panels which were fabricated and processed in accordance with the specifications and procedures accepted for the fabrication and processing of the leading edge structural subsystem (LESS) elements for the space shuttle orbiter. The specimens were then baseline coated and tetraethyl orthosilicate impregnated, as applicable, in accordance with the procedures and requirements of the appropriate LESS production specifications. Three heater bars were ATJ graphite silicon carbide coated with the Vought 'pack cementation' coating process, and three were stackpole grade 2020 graphite silicon carbide coated with the chemical vapor deposition process utilized by Vought in coating the LESS shell development program entry heater elements. Nondestructive test results are reported.

Numerical Analysis of the Elastic Properties of 3D Needled Carbon/Carbon Composites

NASA Astrophysics Data System (ADS)

Tan, Y.; Yan, Y.; Li, X.; Guo, F.

2017-09-01

Based on the observation of microstructures of 3D needled carbon/carbon (C/C) composites, a model of their representative volume element (RVE) considering the true distribution of fibers is established. Using the theories of mesoscopic mechanics and introducing periodic boundary conditions for displacements, their elastic properties, with account of porosity, are determined by finite-element methods. Quasi-static tensile tests were carried out, and the numerical predictions were found to be in good agreement with test results. This means that the RVE model of 3D needled C/C composites can predict their elastic properties efficiently. The effects of needling density, radius of needled fibers, and thickness ratio of a short-cut fiber web and a weftless ply on the elastic constants of the composites are analyzed.

LOX/hydrocarbon fuel carbon formation and mixing data analysis

NASA Technical Reports Server (NTRS)

Fang, J.

1983-01-01

By applying the Priem-Heidmann Generalized-Length vaporization correlation, the computer model developed by the present study predicts the spatial variation of propellant vaporization rate using the injector cold flow results to define the streamtubes. The calculations show that the overall and local propellant vaporization rate and mixture ratio change drastically as the injection element type or the injector operating condition is changed. These results are compared with the regions of carbon formation observed in the photographic combustion testing. The correlation shows that the fuel vaporization rate and the local mixture ratio produced by the injector element have first order effects on the degree of carbon formation.

Study of terrestrial carbon cycling as impacted by mountaintop coal mining in the Southern Appalachian forest region using carbon elemental and isotopic data and remote sensing of land cover change

NASA Astrophysics Data System (ADS)

Fox, J. F.; Campbell, J. E.; Martin, D.

2008-12-01

The need to quantify the impact of human disturbance upon carbon flux and storage has been recently highlighted in order to more accurately budget carbon. One understudied but critical area of research is surface coal mining's impact on terrestrial carbon storage and sediment carbon transport processes-which has been identified as potentially important to understanding fluxes in global carbon budgeting. While national attention has focused on U.S. coal production to maintain a vibrant economy, scientists are concerned that increased coal production could have unforeseen environmental implications if the relationship between coal mining practices and the environment is not better understood. This issue is particularly important to the coal mining region of the Southern Appalachian forest region, which has been responsible for 23.3% of the coal produced in the United States over the past twenty years and seen approximately 300,000 ha of forested land disturbed by surface coal mining during that time period. Our presentation provides results that focus upon terrestrial carbon cycling as impacted by mountaintop coal mining in the Southern Appalachian forest region. In order to study carbon redistribution due to the mining disturbance, our methods make use of measurements of total organic carbon, total organic nitrogen, and carbon and nitrogen stable isotopes of soils and eroded sediments collected in the region as well as published data, consultation with experts and remote sensing of land cover change. It was found that disturbed terrestrial carbon, including soil C, non-soil or plant C, and geogenic C, is approximately 10% of the carbon emitted to the atmosphere during coal combusting and transportation and mining of coal. Quantification of the fate of terrestrial carbon in different pools is provided and discussed including the fate atmosphere during recovery of the terrestrial system; newly deposited coal fragments within the terrestrial soil reservoir; and carbon that is eroded to streams in mined watersheds with different levels of disturbance.

Biogeochemical redox processes and their impact on contaminant dynamics

USGS Publications Warehouse

Borch, Thomas; Kretzschmar, Ruben; Kappler, Andreas; Van Cappellen, Philippe; Ginder-Vogel, Matthew; Campbell, Kate M.

2010-01-01

Life and element cycling on Earth is directly related to electron transfer (or redox) reactions. An understanding of biogeochemical redox processes is crucial for predicting and protecting environmental health and can provide new opportunities for engineered remediation strategies. Energy can be released and stored by means of redox reactions via the oxidation of labile organic carbon or inorganic compounds (electron donors) by microorganisms coupled to the reduction of electron acceptors including humic substances, iron-bearing minerals, transition metals, metalloids, and actinides. Environmental redox processes play key roles in the formation and dissolution of mineral phases. Redox cycling of naturally occurring trace elements and their host minerals often controls the release or sequestration of inorganic contaminants. Redox processes control the chemical speciation, bioavailability, toxicity, and mobility of many major and trace elements including Fe, Mn, C, P, N, S, Cr, Cu, Co, As, Sb, Se, Hg, Tc, and U. Redox-active humic substances and mineral surfaces can catalyze the redox transformation and degradation of organic contaminants. In this review article, we highlight recent advances in our understanding of biogeochemical redox processes and their impact on contaminant fate and transport, including future research needs.

The fate of minor alkali elements in the chemical evolution of salt lakes

PubMed Central

2011-01-01

Alkaline earth elements and alkali metals (Mg, Ca, Na and K) play an important role in the geochemical evolution of saline lakes as the final brine type is defined by the abundance of these elements. The role of major ions in brine evolution has been studied in great detail, but little has been done to investigate the behaviour of minor alkali elements in these systems despite their similar chemical affinities to the major cations. We have examined three major anionic brine types, chloride, sulphate, and bicarbonate-carbonate, in fifteen lakes in North America and Antarctica to determine the geochemical behaviour of lithium, rubidium, strontium, and barium. Lithium and rubidium are largely conservative in all water types, and their concentrations are the result of long-term solute input and concentration through evaporation and/or sublimation. Strontium and barium behaviours vary with anionic brine type. Strontium can be removed in sulphate and carbonate-rich lakes by the precipitation of carbonate minerals. Barium may be removed in chloride and sulphate brines by either the precipitation of barite and perhaps biological uptake. PMID:21992434

Assessing Carbon Storage and Sequestration of Seagrass Meadows on the Pacific Coast of Canada

NASA Astrophysics Data System (ADS)

Postlethwaite, V. R.; McGowan, A. E.; Robinson, C.; Kohfeld, K. E.; Pellatt, M. G.; Yakimishyn, J.; Chastain, S. G.

2016-12-01

Recent estimates suggest that seagrasses are highly efficient carbon sinks, storing a disproportionate amount of carbon for their relatively small area (only approximately 0.2% of the global ocean), and that they may bury carbon up to 12 times faster than terrestrial forests. Unfortunately, seagrass meadows are being lost at a rate of 0.4-2.6% yr-1, potentially releasing 0.15-1.02 Pg (billion tonnes) carbon dioxide into the atmosphere annually. Research on seagrass carbon stocks has been mainly limited to areas in the Mediterranean, Southeast Asia, and Western Australia, and specifically has been very limited in the Northeast Pacific. We aim to characterize the carbon storage and sequestration occurring in the Pacific Rim National Park Reserve and the Clayoquot Sound area, off the western coast of Vancouver Island, British Columbia (BC). Each of our sites varied in environmental characteristics representative of BC's seagrass meadows, including freshwater influence. Six cores, plus one from a "reference" site were taken from each meadow. Loss on ignition (LOI) and elemental analysis will be used to determine organic C and carbonate content. Additionally, we will use dry bulk density, 210Pb dating and seagrass density data to determine carbon accumulation rates and total meadow carbon stocks to provide a comprehensive picture of carbon storage and sequestration in BC's seagrass meadows. Carbon storage results will contribute to global estimates of seagrass carbon stocks via the Commission for Environmental Cooperation, as well as assist in marine ecosystem conservation planning and help in understanding the value of these ecosystems, especially as a means of climate change mitigation.

Carbon budget for a British upland peat catchment.

PubMed

Worrall, Fred; Reed, Mark; Warburton, Jeff; Burt, Tim

2003-08-01

This study describes the analysis of fluvial carbon flux from an upland peat catchment in the North Pennines. Dissolved organic carbon (DOC), pH, alkalinity and calcium were measured in weekly samples, with particulate organic carbon (POC) measured from the suspended sediment load from the stream outlet of an 11.4-km(2) catchment. For calendar year 1999, regular monitoring of the catchment was supplemented with detailed quasi-continuous measurements of flow and stream temperature, and DOC for the months September through November. The measurements were used to calculate the annual flux of dissolved CO(2), dissolved inorganic carbon, DOC and POC from the catchment and were combined with CO(2) and CH(4) gaseous exchanges calculated from previously published values and the observations of water table height within the peat. The study catchment represents a net sink of 15.4+/-11.9 gC/m(2)/yr. Carbon flows calculated for the study catchment are combined with values in the literature, using a Monte Carlo method, to estimate the carbon budget for British upland peat. For all British upland peat the calculation suggests a net carbon sink of between 0.15 and 0.29 MtC/yr. This is the first study to include a comprehensive study of the fluvial export of carbon within carbon budgets and shows the size of the peat carbon sink to be smaller than previous estimates, although sensitivity analysis shows that the primary productivity rather than fluvial carbon flux is a more important element in estimating the carbon budget in this regard.

Solar nebula chemistry - Implications for volatiles in the solar system

NASA Technical Reports Server (NTRS)

Fegley, Bruce, Jr.; Prinn, Ronald G.

1989-01-01

Current theoretical models of solar nebula chemistry which take into account the interplay between chemistry and dynamics are presented for the abundant reactive volatile elements including hydrogen, carbon, nitrogen, oxygen, and sulfur. Results of these models indicate that, in the solar nebula, the dominant carbon and nitrogen gases were CO and NO, whereas, in giant planet subnebulae, the dominant carbon and nitrogen gases were CH4 and NH3; in the solar nebula, the Fe metal grains catalyzed the formation of organic compounds from CO and H2 via the Fischer-Tropsch-type reaction. It was also found that, in solar nebula, bulk FeS formation was kinetically favorable, while FeO incorporation into silicates and bulk Fe3O4 formation were kinetically inhibited. Furthermore, clathrate formation was kinetically inhibited in the solar nebula, while it was kinetically favorable in giant planet subnebulae.

ORGANIC AEROSOL SAMPLING AND ANALYSIS METHODS RESEARCH

EPA Science Inventory

Carbonaceous material is a major component of ambient PM at all locations in the U.S. and it is composed of two major classes: organic carbon (OC, composed of hundreds of individual compounds) and elemental carbon (EC, also referred to as soot, black carbon, or light adsorbing ca...

Utilization of porous carbons derived from coconut shell and wood in natural rubber

USDA-ARS?s Scientific Manuscript database

The porous carbons derived from cellulose are renewable and environmentally friendly. Coconut shell and wood derived porous carbons were characterized with elemental analysis, ash content, x-ray diffraction, infrared absorbance, particle size, surface area, and pore volume. The results were compared...

Knowledge of Pest Resistance in SiC/BN/SiC Composites Improved

NASA Technical Reports Server (NTRS)

Thomas-Ogbuji, Linus U.

2002-01-01

Ceramic-matrix composites (CMC's) consisting of a silicon carbide matrix reinforced with boron-nitride- (BN-) coated silicon carbide (SiC) fibers are strong contenders for commercial and aerospace applications (in particular, the hot sections of high-performance turbine engines in advanced aircraft and generators). They have very good mechanical properties below approximately 600 C and above approximately 1000 C. Between those temperatures, however, the BN coating oxidizes easily, and the oxidation of the SiC matrix is too sluggish to seal off the composite with a protective layer of silica. In that temperature interval, the preferential oxidation of the BN weakens and embrittles the composite. That phenomenon, referred to as "pest" degradation, is the focus of this work, which aims to identify the causes of and remedies for pesting. Previous work established that pesting in Hi-Nicalon (Nippon Carbon Co., Ltd., Japan)/SiC composites was caused by a layer of free carbon that undermined the oxidation resistance of the BN. New work suggests that composites containing a source of carbon are prone to severe pesting and that those that are free of elemental carbon are resistant pesting. Pest resistance was assessed by exposing machined samples for 100 to 150 hr in an atmospheric burner rig at 600 to 1100 C, followed by a tensile fracture test to measure residual mechanical properties and by characterization of the interphase microstructure. Whether the elemental carbon came from intrinsic or extrinsic sources, its presence induced the tensile strength to drop by over 50 percent in the burner rig, with an even more severe loss of fracture strain. A likely mechanism by which burnoff of the carbon layer exposes the BN to accelerated flank attack by ambient oxidants is shown. The BN is replaced with borosilicates that attack the fiber, and ultimately with silica that embrittles the composites by rigidly bonding components. Thus, the study has shown that pesting can be prevented in SiC/BN/SiC, or at least reduced, by simply excluding free carbon. These studies continue, and plans for future work include investigating the role that carbon may play elsewhere in the interphase region.

Seasonal Cyclicity in Trace Elements and Stable Isotopes of Modern Horse Enamel.

PubMed

de Winter, Niels J; Snoeck, Christophe; Claeys, Philippe

2016-01-01

The study of stable isotopes in fossil bioapatite has yielded useful results and has shown that bioapatites are able to faithfully record paleo-environmental and paleo-climatic parameters from archeological to geological timescales. In an effort to establish new proxies for the study of bioapatites, intra-tooth records of enamel carbonate stable isotope ratios from a modern horse are compared with trace element profiles measured using laboratory micro X-Ray Fluorescence scanning. Using known patterns of tooth eruption and the relationship between stable oxygen isotopes and local temperature seasonality, an age model is constructed that links records from six cheek upper right teeth from the second premolar to the third molar. When plotted on this age model, the trace element ratios from horse tooth enamel show a seasonal pattern with a small shift in phase compared to stable oxygen isotope ratios. While stable oxygen and carbon isotopes in tooth enamel are forced respectively by the state of the hydrological cycle and the animal's diet, we argue that the seasonal signal in trace elements reflects seasonal changes in dust intake and diet of the animal. The latter explanation is in agreement with seasonal changes observed in carbon isotopes of the same teeth. This external forcing of trace element composition in mammal tooth enamel implies that trace element ratios may be used as proxies for seasonal changes in paleo-environment and paleo-diet.

Seasonal Cyclicity in Trace Elements and Stable Isotopes of Modern Horse Enamel

PubMed Central

Snoeck, Christophe; Claeys, Philippe

2016-01-01

The study of stable isotopes in fossil bioapatite has yielded useful results and has shown that bioapatites are able to faithfully record paleo-environmental and paleo-climatic parameters from archeological to geological timescales. In an effort to establish new proxies for the study of bioapatites, intra-tooth records of enamel carbonate stable isotope ratios from a modern horse are compared with trace element profiles measured using laboratory micro X-Ray Fluorescence scanning. Using known patterns of tooth eruption and the relationship between stable oxygen isotopes and local temperature seasonality, an age model is constructed that links records from six cheek upper right teeth from the second premolar to the third molar. When plotted on this age model, the trace element ratios from horse tooth enamel show a seasonal pattern with a small shift in phase compared to stable oxygen isotope ratios. While stable oxygen and carbon isotopes in tooth enamel are forced respectively by the state of the hydrological cycle and the animal’s diet, we argue that the seasonal signal in trace elements reflects seasonal changes in dust intake and diet of the animal. The latter explanation is in agreement with seasonal changes observed in carbon isotopes of the same teeth. This external forcing of trace element composition in mammal tooth enamel implies that trace element ratios may be used as proxies for seasonal changes in paleo-environment and paleo-diet. PMID:27875538

Changing fluxes of carbon and other solutes from the Mekong River

PubMed Central

Li, Siyue; Bush, Richard T.

2015-01-01

Rivers are an important aquatic conduit that connects terrestrial sources of dissolved inorganic carbon (DIC) and other elements with oceanic reservoirs. The Mekong River, one of the world’s largest rivers, is firstly examined to explore inter-annual fluxes of dissolved and particulate constituents during 1923–2011 and their associated natural or anthropogenic controls. Over this period, inter-annual fluxes of dissolved and particulate constituents decrease, while anthropogenic activities have doubled the relative abundance of SO42−, Cl− and Na+. The estimated fluxes of solutes from the Mekong decrease as follows (Mt/y): TDS (40.4) > HCO3− (23.4) > Ca2+ (6.4) > SO42− (3.8) > Cl− (1.74)~Na+ (1.7) ~ Si (1.67) > Mg2+ (1.2) > K+ (0.5). The runoff, land cover and lithological composition significantly contribute to dissolved and particulate yields globally. HCO3− and TDS yields are readily predicted by runoff and percent of carbonate, while TSS yield by runoff and population density. The Himalayan Rivers, including the Mekong, are a disproportionally high contributor to global riverine carbon and other solute budgets, and are of course underlined. The estimated global riverine HCO3− flux (Himalayan Rivers included) is 34014 × 109 mol/y (0.41 Pg C/y), 3915 Mt/y for solute load, including HCO3−, and 13553 Mt/y for TSS. Thereby this study illustrates the importance of riverine solute delivery in global carbon cycling. PMID:26522820

Changing fluxes of carbon and other solutes from the Mekong River.

PubMed

Li, Siyue; Bush, Richard T

2015-11-02

Rivers are an important aquatic conduit that connects terrestrial sources of dissolved inorganic carbon (DIC) and other elements with oceanic reservoirs. The Mekong River, one of the world's largest rivers, is firstly examined to explore inter-annual fluxes of dissolved and particulate constituents during 1923-2011 and their associated natural or anthropogenic controls. Over this period, inter-annual fluxes of dissolved and particulate constituents decrease, while anthropogenic activities have doubled the relative abundance of SO4(2-), Cl(-) and Na(+). The estimated fluxes of solutes from the Mekong decrease as follows (Mt/y): TDS (40.4) > HCO3(-) (23.4) > Ca(2+) (6.4) > SO4(2-) (3.8) > Cl(-) (1.74)~Na(+) (1.7) ~ Si (1.67) > Mg(2+) (1.2) > K(+ 0.5). The runoff, land cover and lithological composition significantly contribute to dissolved and particulate yields globally. HCO3(-) and TDS yields are readily predicted by runoff and percent of carbonate, while TSS yield by runoff and population density. The Himalayan Rivers, including the Mekong, are a disproportionally high contributor to global riverine carbon and other solute budgets, and are of course underlined. The estimated global riverine HCO3(-) flux (Himalayan Rivers included) is 34,014 × 10(9) mol/y (0.41 Pg C/y), 3915 Mt/y for solute load, including HCO3(-), and 13,553 Mt/y for TSS. Thereby this study illustrates the importance of riverine solute delivery in global carbon cycling.

Characterization of Santa Catarina (Brazil) coal with respect to human health and environmental concerns

USGS Publications Warehouse

Silva, L.F.O.; Oliveira, M.L.S.; Boit, K.M.; Finkelman, R.B.

2009-01-01

The current paper presents the concentration, distribution, and modes of occurrence of trace elements of 13 coals from south Brazil. The samples were collected in the state of Santa Catarina. Chemical analyses and the high ash yields indicate that all studied coals are rich in mineral matter, with SiO2 and Al2O3 dominating as determined by inductively coupled plasma-atomic emission spectrometry (ICP-AES). Quartz is the main mineral species and is associated with minor levels of feldspars, kaolinite, hematite, and iron-rich carbonates. The contents of trace elements, including As, Pb, Cd, Ni, Cr, Mn, Be, V, U, Zn, Li, Cu, Tl, and Ni, in coals were determined. A comparison of ranges and means of elemental concentrations in Santa Catarina, Brazil, and world coals shows that the ranges of most elements in Santa Catarina coal are very close to the usual worldwide concentration ranges in coal. ?? Springer Science+Business Media B.V. 2008.

Removal performance of elemental mercury by low-cost adsorbents prepared through facile methods of carbonisation and activation of coconut husk.

PubMed

Johari, Khairiraihanna; Alias, Afidatul Shazwani; Saman, Norasikin; Song, Shiow Tien; Mat, Hanapi

2015-01-01

The preparation of chars and activated carbon as low-cost elemental mercury adsorbents was carried out through the carbonisation of coconut husk (pith and fibre) and the activation of chars with potassium hydroxide (KOH), respectively. The synthesised adsorbents were characterised by using scanning electron microscopy, Fourier transform infrared spectroscopy and nitrogen adsorption/desorption analysis. The elemental mercury removal performance was measured using a conventional flow type packed-bed adsorber. The physical and chemical properties of the adsorbents changed as a result of the carbonisation and activation process, hence affecting on the extent of elemental mercury adsorption. The highest elemental mercury (Hg°) adsorption capacity was obtained for the CP-CHAR (3142.57 µg g(-1)), which significantly outperformed the pristine and activated carbon adsorbents, as well as higher than some adsorbents reported in the literature. © The Author(s) 2014.

Gases and trace elements in soils at the North Silver Bell deposit, Pima County, Arizona

USGS Publications Warehouse

Hinkle, M.E.; Dilbert, C.A.

1984-01-01

Soil samples were collected over the North Silver Bell porphyry copper deposit near Tucson, Arizona. Volatile elements and compounds in gases derived from the soils and metallic elements in the soils were analyzed in order: (1) to see which volatile constituents of the soils might be indicative of the ore body or the alteration zones; and (2) to distinguish the ore and alteration zones by comparison of trace elements in the soil. Plots of analytical data on trace elements in soils indicated a typical distribution pattern for metals around a porphyry copper deposit, with copper, molybdenum, and arsenic concentrations higher over the ore body, and zinc, lead, and silver concentrations higher over the alteration zones. Higher than average concentrations of helium, carbon disulfide, and sulfur dioxide adsorbed on soils were found over the ore body, whereas higher concentrations of carbon dioxide and carbonyl sulfide were found over the alteration zones. ?? 1984.

Growth of normally-immiscible materials (NIMs), binary alloys, and metallic fibers by hyperbaric laser chemical vapor deposition

NASA Astrophysics Data System (ADS)

Maxwell, J. L.; Black, M. R.; Chavez, C. A.; Maskaly, K. R.; Espinoza, M.; Boman, M.; Landstrom, L.

2008-06-01

This work demonstrates that two or more elements of negligible solubility (and no known phase diagram) can be co-deposited in fiber form by hyperbaric-pressure laser chemical vapor deposition (HP-LCVD). For the first time, Hg-W alloys were grown as fibers from mixtures of tungsten hexafluoride, mercury vapor, and hydrogen. This new class of materials is termed normally-immiscible materials (NIMs), and includes not only immiscible materials, but also those elemental combinations that have liquid states at exclusive temperatures. This work also demonstrates that a wide variety of other binary and ternary alloys, intermetallics, and mixtures can be grown as fibers, e.g. silicon-tungsten, aluminum-silicon, boron-carbon-silicon, and titanium-carbon-nitride. In addition, pure metallic fibers of aluminum, titanium, and tungsten were deposited, demonstrating that materials of high thermal conductivity can indeed be grown in three-dimensions, provided sufficient vapor pressures are employed. A wide variety of fiber properties and microstructures resulted depending on process conditions; for example, single crystals, fine-grained alloys, and glassy metals could be deposited.

Apportionment of urban aerosol sources in Chongqing (China) using synergistic on-line techniques

NASA Astrophysics Data System (ADS)

Chen, Yang; Yang, Fumo

2016-04-01

The sources of ambient fine particulate matter (PM2.5) during wintertime at a background urban location in Chongqing (southwestern China) have been determined. Aerosol chemical composition analyses were performed using multiple on-line techniques, such as single particle aerosol mass spectrometer (SPAMS) for single particle chemical composition, on-line elemental carbon-organic carbon analyzer (on-line OC-EC), on-line X-ray fluorescence (XRF) for elements, and in-situ Gas and Aerosol Compositions monitor (IGAC) for water-soluble ions in PM2.5. All the datasets from these techniques have been adjusted to a 1-h time resolution for receptor model input. Positive matrix factorization (PMF) has been used for resolving aerosol sources. At least six sources, including domestic coal burning, biomass burning, dust, traffic, industrial and secondary/aged factors have been resolved and interpreted. The synergistic on-line techniques were helpful for identifying aerosol sources more clearly than when only employing the results from the individual techniques. This results are useful for better understanding of aerosol sources and atmospheric processes.

Selenium deficiency risk predicted to increase under future climate change

PubMed Central

Jones, Gerrad D.; Droz, Boris; Greve, Peter; Gottschalk, Pia; Poffet, Deyan; McGrath, Steve P.; Seneviratne, Sonia I.; Smith, Pete; Winkel, Lenny H. E.

2017-01-01

Deficiencies of micronutrients, including essential trace elements, affect up to 3 billion people worldwide. The dietary availability of trace elements is determined largely by their soil concentrations. Until now, the mechanisms governing soil concentrations have been evaluated in small-scale studies, which identify soil physicochemical properties as governing variables. However, global concentrations of trace elements and the factors controlling their distributions are virtually unknown. We used 33,241 soil data points to model recent (1980–1999) global distributions of Selenium (Se), an essential trace element that is required for humans. Worldwide, up to one in seven people have been estimated to have low dietary Se intake. Contrary to small-scale studies, soil Se concentrations were dominated by climate–soil interactions. Using moderate climate-change scenarios for 2080–2099, we predicted that changes in climate and soil organic carbon content will lead to overall decreased soil Se concentrations, particularly in agricultural areas; these decreases could increase the prevalence of Se deficiency. The importance of climate–soil interactions to Se distributions suggests that other trace elements with similar retention mechanisms will be similarly affected by climate change. PMID:28223487

Selenium deficiency risk predicted to increase under future climate change.

PubMed

Jones, Gerrad D; Droz, Boris; Greve, Peter; Gottschalk, Pia; Poffet, Deyan; McGrath, Steve P; Seneviratne, Sonia I; Smith, Pete; Winkel, Lenny H E

2017-03-14

Deficiencies of micronutrients, including essential trace elements, affect up to 3 billion people worldwide. The dietary availability of trace elements is determined largely by their soil concentrations. Until now, the mechanisms governing soil concentrations have been evaluated in small-scale studies, which identify soil physicochemical properties as governing variables. However, global concentrations of trace elements and the factors controlling their distributions are virtually unknown. We used 33,241 soil data points to model recent (1980-1999) global distributions of Selenium (Se), an essential trace element that is required for humans. Worldwide, up to one in seven people have been estimated to have low dietary Se intake. Contrary to small-scale studies, soil Se concentrations were dominated by climate-soil interactions. Using moderate climate-change scenarios for 2080-2099, we predicted that changes in climate and soil organic carbon content will lead to overall decreased soil Se concentrations, particularly in agricultural areas; these decreases could increase the prevalence of Se deficiency. The importance of climate-soil interactions to Se distributions suggests that other trace elements with similar retention mechanisms will be similarly affected by climate change.

Local involvement in measuring and governing carbon stocks in China, Vietnam, Indonesia and Laos

Treesearch

Michael Køie Poulsen

2013-01-01

An important element of MRV is to ensure accurate measurements of carbon stocks. Measuring trees on the ground may be needed for ground truthing of remote sensing results. It can also provide more accurate carbon stock monitoring than remote sensing alone. Local involvement in measuring trees for monitoring of carbon stocks may be advantageous in several ways....

Test and evaluation of the heat recovery incinerator system at Naval Station, Mayport, Florida

NASA Astrophysics Data System (ADS)

1981-05-01

This report describes test and evaluation of the two-ton/hr heat recovery incinerator (HRI) facility located at Mayport Naval Station, Fla., carried out during November and December 1980. The tests included: (1) Solid Waste: characterization, heating value, and ultimate analysis, (2) Ash: moisture, combustibles, and heating values of both bottom and cyclone ashes; Extraction Procedure toxicity tests on leachates from both bottom and cyclone ashes; trace metals in cyclone particulates, (3) Stack Emissions: particulates (quantity and size distribution), chlorides, oxygen, carbon dioxide, carbon monoxide, and trace elements, and (4) Heat and Mass Balance: all measurements required to carry out complete heat and mass balance calculations over the test period. The overall thermal efficiency of the HRI facility while operating at approximately 1.0 ton/hr was found to be 49% when the primary Btu equivalent of the electrical energy consumed during the test program was included.

Important sources and chemical species of ambient fine particles related to adverse health effects

NASA Astrophysics Data System (ADS)

Heo, J.

2017-12-01

Although many epidemiological studies have reported that exposure to ambient fine particulate matter (PM2.5) has been linked to increases in mortality and mobidity health outcomes, the key question of which chemical species and sources of PM2.5 are most harmful to public health remains unanswered in the air pollution research area. This study was designed to address the key question with evaluating the risks of exposure to chemical species and source-specific PM2.5 mass on morbidity. Hourly measurements of PM2.5 mass and its major chemical species, including organic carbon, elemental carbon, ions, and trace elements, were observed from January 1 to December 31, 2013 at four of the PM2.5 supersites in urban environments in Korea and the reuslts were used in a positive matrix factorization to estimate source contributions to PM2.5 mass. Nine sources, including secondary sulfate, secondary nitrate, mobile, biomass burning, roadway emission, industry, oil combustion, soil, and aged sea salt, were identified and secondary inorganic aerosol factors (i.e. secondary sulfalte, and secondary nitrate) were the dominant sources contributing to 40% of the total PM2.5 mass in the study region. In order to evaluate the risks of exposure to chemical species and sources of PM2.5 on morbidity, emergency room visits for cardivascular disease and respiratory disease were considered. Hourly health outcomes were compared with hourly measurments of the PM2.5 chemical species and sources using a poission generalized linear model incorporating natural splines, as well as time-stratified case-crossover design. The PM2.5 mass and speveral chemical components, such as organic carbon, elemetal carbon, zinc, and potassium, were strongly associated with morbidity. Source-apporitionmened PM2.5 mass derived from biomass burning, and mobile sources, was significantly associated with cardiovascular and respiratory diseases. The findings represent that local combustion may be particularly important contributor to PM2.5, leading to adverse human health effects.

Hydrochemical Characteristics and Formation of the Saline or Salty Springs in Eastern Sichuan Basin of China

NASA Astrophysics Data System (ADS)

Zhou, X.

2017-12-01

Saline or salty springs provide important information on the hydrogeochemical processes and hydrology within subsurface aquifers. More than 20 saline and salty springs occur in the core of anticlines in the eastern Sichuan Basin in southwestern China where the Lower and Middle Triassic carbonates outcrop. Water samples of 8 saline and salty springs (including one saline hot spring) were collected for analyses of the major and minor constituents, trace elements and stable oxygen and hydrogen isotopes. The TDS of the springs range from 4 to 83 g/L, and they are mainly of Cl-Na type. Sr, Ba and Li are the predominant trace elements. The δ2H and δ18O of the water samples indicate that they are of meteoric origin. The source of salinity of the springs originates from dissolution of minerals in the carbonates, including halite, gypsum, calcite and dolomite. The formation mechanism of the springs is that groundwater receives recharge from infiltration of precipitation, undergoes shallow or deep circulation in the core of the anticline and incongruent dissolution of the salt-bearing carbonates occurs, and emerges in the river valley in the form of springs with relatively high TDS. The 8 springs can be classified into 4 springs of shallow groundwater circulation and 4 springs of deep groundwater circulation according to the depth of groundwater circulation, 7 springs of normal temperature and 1 hot spring according to temperature. There are also 2 up-flow springs: the carbonate aquifers are overlain by relatively impervious sandstone and shale, groundwater may flows up to the ground surface through the local portion of the overlying aquiclude where fractures were relatively well developed, and emerges as an up-flow spring. Knowledge of the hydrochemical characteristics and the geneses of the saline and salty springs are of important significance for the utilization and preservation of the springs.

Formation of cerussite and hydrocerussite during adsorption of lead from aqueous solution on oxidized carbons by cold oxygen plasma

NASA Astrophysics Data System (ADS)

De Velasco Maldonado, Paola S.; Hernández-Montoya, Virginia; Concheso, A.; Montes-Morán, Miguel A.

2016-11-01

A new procedure of elimination of Pb2+ from aqueous solution using carbon adsorbents, in which high amounts of cerussite and hydrocerussite are deposited on the carbon surfaces, is reported. The procedure includes the preparation of carbons from selected lignocellulosic wastes (pecan nut shells and peach stones) by single carbonization and further oxidation with cold oxygen plasma. The materials prior and after the oxidation treatment were characterized using elemental analysis, FT-IR spectroscopy, SEM/EDX analysis, adsorption of N2 at -196 °C and X-ray photoelectron spectroscopy. The adsorption of Pb2+ was carried out in batch systems under constant agitation. The formation of cerussite and hydrocerussite on the spent carbon surfaces was confirmed by XRD, SEM/EDX and FT-IR. A Pb2+ removal mechanism is proposed in which a co-precipitation of lead nitrate and calcium carbonate would render the formation of the lead carbonates. In such mechanism, the occurrence of CaCO3 on the surface of the adsorbents plays a crucial role. The presence of calcium carbonate on the precursors is understood on the basis of the thermal evolution of calcium oxalate originally present in the biomass. The oxygen plasma treatment helps to expose the calcium carbonate nanocrystals thus improving dramatically the removal capacity of Pb2+. Accordingly, retention capacities as high as 63 mg of Pb2+ per gram of adsorbent have been attained.

Physiological, biomass elemental composition and proteomic analyses of Escherichia coli ammonium-limited chemostat growth, and comparison with iron- and glucose-limited chemostat growth

PubMed Central

Folsom, James Patrick

2015-01-01

Escherichia coli physiological, biomass elemental composition and proteome acclimations to ammonium-limited chemostat growth were measured at four levels of nutrient scarcity controlled via chemostat dilution rate. These data were compared with published iron- and glucose-limited growth data collected from the same strain and at the same dilution rates to quantify general and nutrient-specific responses. Severe nutrient scarcity resulted in an overflow metabolism with differing organic byproduct profiles based on limiting nutrient and dilution rate. Ammonium-limited cultures secreted up to 35  % of the metabolized glucose carbon as organic byproducts with acetate representing the largest fraction; in comparison, iron-limited cultures secreted up to 70  % of the metabolized glucose carbon as lactate, and glucose-limited cultures secreted up to 4  % of the metabolized glucose carbon as formate. Biomass elemental composition differed with nutrient limitation; biomass from ammonium-limited cultures had a lower nitrogen content than biomass from either iron- or glucose-limited cultures. Proteomic analysis of central metabolism enzymes revealed that ammonium- and iron-limited cultures had a lower abundance of key tricarboxylic acid (TCA) cycle enzymes and higher abundance of key glycolysis enzymes compared with glucose-limited cultures. The overall results are largely consistent with cellular economics concepts, including metabolic tradeoff theory where the limiting nutrient is invested into essential pathways such as glycolysis instead of higher ATP-yielding, but non-essential, pathways such as the TCA cycle. The data provide a detailed insight into ecologically competitive metabolic strategies selected by evolution, templates for controlling metabolism for bioprocesses and a comprehensive dataset for validating in silico representations of metabolism. PMID:26018546

Quantification of diagenesis in Cenozoic sharks: Elemental and mineralogical changes

NASA Astrophysics Data System (ADS)

Labs-Hochstein, Joann; MacFadden, Bruce J.

2006-10-01

Diagenesis of bone during fossilization is pervasive, however, the extent of this process varies with depositional environment. This study quantifies diagenesis of shark vertebral centra through analysis of a suite of physical and chemical characters including crystallinty index (CI), carbonate content, and elemental concentrations. Although shark skeletons are initially cartilaginous, the soft cartilage of the vertebral centra is replaced with carbonate hydroxyapatite during growth. Nine vertebral centra are analyzed from lamnoid (Lamnoidea) sharks ranging in age from the cretaceous to recent using Fourier transform infrared spectroscopy (FT-IR) and inductively coupled plasma mass spectrometry (ICPMS). The variables CI, carbonate content, rare earth element (REE) concentrations, Ca/P, Ba/Ca, Sr/Ba, (La/Yb) N, (La/Y) N, (La/Yb) N vs. (La/Sm) N, La/Yb, and Ce anomalies elucidate the diagenetic and depositional environments of the seven fossil vertebral centra. The two extant centra demonstrate the initial, unaltered end-member conditions for these variables. Two fossil vertebral centra ( Carcharodon megalodon and Isurus hastalis) demonstrate a strong terrestrial influence during diagenesis (distinctive flattening of shale-normalized REE patterns) that masked the seawater signal. Three centra ( Carcharodon auriculatus, Carcharodon angustidens, and Creotxyrhina mantelli) have indications of some terrestrial influx evident by some flattening of the REE patterns relative to seawater. The terrestrial influence in these five shark centra ( C. megalodon, I. hastalis, C. auriculatus, C. angustidens and C. mantelli) are interpreted to represent a primarily nearshore habitat for these species. In contrast, the two Otodus obliquus centra have REE patterns that represent the original seawater signal and have no indications of terrigenous input. These results indicate that fossil shark vertebral centra have the potential to understand diagenesis and reconstruct paleooceanographic environments.

The Chemical Evolution of the Bootes I Ultra-faint Dwarf Galaxy

NASA Astrophysics Data System (ADS)

Frebel, Anna; Norris, John E.; Gilmore, Gerard; Wyse, Rosemary F. G.

2016-08-01

We present chemical abundance measurements of two metal-poor red giant stars in the ultra-faint dwarf galaxy Boötes I, based on Magellan/MIKE high-resolution spectra. For Boo-980, with {{[Fe/H]}}=-3.1, we present the first elemental abundance measurements, while Boo-127, with {{[Fe/H]}}=-2.0, shows abundances in good agreement with previous measurements. Light and iron-peak element abundance ratios in the two Boötes I stars, as well as those of most other Boötes I members, collected from the literature, closely resemble those of regular metal-poor halo stars. Neutron-capture element abundances Sr and Ba are systematically lower than the main halo trend and also show a significant abundance spread. Overall, this is similar to what has been found for other ultra-faint dwarf galaxies. We apply corrections to the carbon abundances (commensurate with stellar evolutionary status) of the entire sample and find 21% of stars to be carbon-enhanced metal-poor (CEMP) stars, compared to 13% without using the carbon correction. We reassess the metallicity distribution functions for the CEMP stars and non-CEMP stars, and confirm earlier claims that CEMP stars might belong to a different, earlier population. Applying a set of abundance criteria to test to what extent Boötes I could be a surviving first galaxy suggests that it is one of the earliest assembled systems that perhaps received gas from accretion from other clouds in the system, or from swallowing a first galaxy or building block type object. This resulted in the two stellar populations observable today. This paper includes data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile.

EXPANDING THE CATALOG: CONSIDERING THE IMPORTANCE OF CARBON, MAGNESIUM, AND NEON IN THE EVOLUTION OF STARS AND HABITABLE ZONES

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

Truitt, Amanda; Young, Patrick A.

Building on previous work, we have expanded our catalog of evolutionary models for stars with variable composition; here we present models for stars of mass 0.5–1.2 M {sub ⊙}, at scaled metallicities of 0.1–1.5 Z {sub ⊙}, and specific C/Fe, Mg/Fe, and Ne/Fe values of 0.58–1.72 C/Fe{sub ⊙}, 0.54–1.84 Mg/Fe{sub ⊙}, and 0.5–2.0 Ne/Fe{sub ⊙}, respectively. We include a spread in abundance values for carbon and magnesium based on observations of their variability in nearby stars; we choose an arbitrary spread in neon abundance values commensurate with the range seen in other low Z elements due to the difficult naturemore » of obtaining precise measurements of neon abundances in stars. As indicated by the results of Truitt et al., it is essential that we understand how differences in individual elemental abundances, and not just the total scaled metallicity, can measurably impact a star’s evolutionary lifetime and other physical characteristics. In that work, we found that oxygen abundances significantly impacted the stellar evolution; carbon, magnesium, and neon are potentially important elements to individually consider due to their relatively high (but also variable) abundances in stars. We present 528 new stellar main-sequence models, and we calculate the time-dependent evolution of the associated habitable zone boundaries for each based on mass, temperature, and luminosity. We also reintroduce the 2 Gyr “Continuously Habitable Zone” (CHZ{sub 2}) as a useful tool to help gauge the habitability potential for a given planetary system.« less

Gas and aerosol carbon in California: comparison of measurements and model predictions in Pasadena and Bakersfield.

EPA Science Inventory

Co-located measurements of fine particulate matter (PM2.5) organic carbon (OC), elemental carbon, radiocarbon (14C), speciated volatile organic compounds (VOCs),and OH radicals during the CalNex field campaign provide a unique opportunity to evaluate the Community Multiscale Air ...

CHARACTERIZATION OF ACTIVATED CARBONS' PHYSICAL AND CHEMICAL PROPERTIES IN RELATION TO THEIR MERCURY ADSORPTION

EPA Science Inventory

The paper gives results of a characterization of the physical and chemical properties of the activated carbons used for elemental mercury (Hgo) adsorption, in order to understand the role of oxygen surface functional groups on the mechanism of Hgo adsorption by activated carbons....

THE EFFECT OF ACTIVATED CARBON SURFACE MOISTURE ON LOW TEMPERATURE MERCURY ADSORPTION

EPA Science Inventory

Experiments with elemental mercury (Hg0) adsorption by activated carbons were performed using a bench-scale fixed-bed reactor at room temperature (27 degrees C) to determine the role of surface moisture in capturing Hg0. A bituminous-coal-based activated carbon (BPL) and an activ...

Carbon-, sulfur-, and phosphorus-based charge transfer reactions in inductively coupled plasma-atomic emission spectrometry

NASA Astrophysics Data System (ADS)

Grindlay, Guillermo; Gras, Luis; Mora, Juan; de Loos-Vollebregt, Margaretha T. C.

2016-01-01

In this work, the influence of carbon-, sulfur-, and phosphorus-based charge transfer reactions on the emission signal of 34 elements (Ag, Al, As, Au, B, Ba, Be, Ca, Cd, Co, Cr, Cu, Fe, Ga, Hg, I, In, Ir, K, Li, Mg, Mn, Na, Ni, P, Pb, Pd, Pt, S, Sb, Se, Sr, Te, and Zn) in axially viewed inductively coupled plasma-atomic emission spectrometry has been investigated. To this end, atomic and ionic emission signals for diluted glycerol, sulfuric acid, and phosphoric acid solutions were registered and results were compared to those obtained for a 1% w w- 1 nitric acid solution. Experimental results show that the emission intensities of As, Se, and Te atomic lines are enhanced by charge transfer from carbon, sulfur, and phosphorus ions. Iodine and P atomic emission is enhanced by carbon- and sulfur-based charge transfer whereas the Hg atomic emission signal is enhanced only by carbon. Though signal enhancement due to charge transfer reactions is also expected for ionic emission lines of the above-mentioned elements, no experimental evidence has been found with the exception of Hg ionic lines operating carbon solutions. The effect of carbon, sulfur, and phosphorus charge transfer reactions on atomic emission depends on (i) wavelength characteristics. In general, signal enhancement is more pronounced for electronic transitions involving the highest upper energy levels; (ii) plasma experimental conditions. The use of robust conditions (i.e. high r.f. power and lower nebulizer gas flow rates) improves carbon, sulfur, and phosphorus ionization in the plasma and, hence, signal enhancement; and (iii) the presence of other concomitants (e.g. K or Ca). Easily ionizable elements reduce ionization in the plasma and consequently reduce signal enhancement due to charge transfer reactions.

Trace element geochemistry and mineralogy of coal from Samaleswari open cast coal block (S-OCB), Eastern India

NASA Astrophysics Data System (ADS)

Saha, Debasree; Chatterjee, Debashis; Chakravarty, Sanchita; Mazumder, Madhurina

2018-04-01

Coal samples of Samaleswari open cast coal block (S-OCB) are high ash (Aad, mean value 35.43%) and low sulphur content (St, on dry basis, mean value 0.91% < 1%) in quality. The stratigraphic variation of volatile matter and fixed carbon (dry ash-free) reflect a progress of coal metamorphism with depth that accordance to the coal rank variation from lignite to high volatile bituminous in the studied borehole. The younger coal seams have greater detrital minerals (quartz, illite, rutile) influence whereas older coal seams have greater authigenic mineral (kaolinite, dolomite, siderite, apatite) contribution that are possibly due to subsidence and sediment transportation. In S-OCB coal trace elements affinities in-between mineral and organic fraction are identified with statistical hierarchical cluster analysis. The work is further supported by the use of chemical fractionation experiment that reveals the multi mode of occurrence of several environmentally concern and interested trace elements (Sb, As, Be, Cd, Cr, Co, Cu, Pb, Mn, Ni, Zn). Among the analysed trace elements Co, Mn and Zn have major silicate association along with significant carbonate/oxide/monosulfide association. Whereas As, Cd, Cu, Pb and Ni have dominant pyritic association with notable silicate and carbonate/oxide/monosulfide association. The rest three elements (Sb, Be, Cr) have principally organic association with minor silicate and carbonate/oxide/monosulfide association. The stratigraphic variation of organo-mineral matrix content and detrital-authigenic mineral ratio are primarily related to coal rank. Geochemical character of coal also reflects a light towards proper utilisation of S-OCB coal from technical and environmental view point.

Projecting changes in Everglades soil biogeochemistry for carbon and other key elements, to possible 2060 climate and hydrologic scenarios.

PubMed

Orem, William; Newman, Susan; Osborne, Todd Z; Reddy, K Ramesh

2015-04-01

Based on previously published studies of elemental cycling in Everglades soils, we projected how soil biogeochemistry, specifically carbon, nitrogen, phosphorus, sulfur, and mercury might respond to climate change scenarios projected for 2060 by the South Florida Water Management Model. Water budgets and stage hydrographs from this model with future scenarios of a 10% increased or decreased rainfall, a 1.5 °C rise in temperature and associated increase in evapotranspiration (ET) and a 0.5 m rise in sea level were used to predict resulting effects on soil biogeochemistry. Precipitation is a much stronger driver of soil biogeochemical processes than temperature, because of links among water cover, redox conditions, and organic carbon accumulation in soils. Under the 10% reduced rainfall scenario, large portions of the Everglades will experience dry down, organic soil oxidation, and shifts in soil redox that may dramatically alter biogeochemical processes. Lowering organic soil surface elevation may make portions of the Everglades more vulnerable to sea level rise. The 10% increased rainfall scenario, while potentially increasing phosphorus, sulfur, and mercury loading to the ecosystem, would maintain organic soil integrity and redox conditions conducive to normal wetland biogeochemical element cycling. Effects of increased ET will be similar to those of decreased precipitation. Temperature increases would have the effect of increasing microbial processes driving biogeochemical element cycling, but the effect would be much less than that of precipitation. The combined effects of decreased rainfall and increased ET suggest catastrophic losses in carbon- and organic-associated elements throughout the peat-based Everglades.

Influence of carbon and lipid sources on variation of mercury and other trace elements in polar bears (Ursus maritimus).

PubMed

Routti, Heli; Letcher, Robert J; Born, Erik W; Branigan, Marsha; Dietz, Rune; Evans, Thomas J; McKinney, Melissa A; Peacock, Elizabeth; Sonne, Christian

2012-12-01

In the present study, the authors investigated the influence of carbon and lipid sources on regional differences in liver trace element (As, Cd, Cu, total Hg, Mn, Pb, Rb, Se, and Zn) concentrations measured in polar bears (Ursus maritimus) (n = 121) from 10 Alaskan, Canadian Arctic, and East Greenland subpopulations. Carbon and lipid sources were assessed using δ(13) C in muscle tissue and fatty acid (FA) profiles in subcutaneous adipose tissue as chemical tracers. A negative relationship between total Hg and δ(13) C suggested that polar bears feeding in areas with higher riverine inputs of terrestrial carbon accumulate more Hg than bears feeding in areas with lower freshwater input. Mercury concentrations were also positively related to the FA 20:1n-9, which is biosynthesized in large amounts in Calanus copepods. This result raises the hypothesis that Calanus glacialis are an important link in the uptake of Hg in the marine food web and ultimately in polar bears. Unadjusted total Hg, Se, and As concentrations showed greater geographical variation among polar bear subpopulations compared with concentrations adjusted for carbon and lipid sources. The Hg concentrations adjusted for carbon and lipid sources in Bering-Chukchi Sea polar bear liver tissue remained the lowest among subpopulations. Based on these findings, the authors suggest that carbon and lipid sources for polar bears should be taken into account when one is assessing spatial and temporal trends of long-range transported trace elements. Copyright © 2012 SETAC.

Isotope Geochemistry of Possible Terrestrial Analogue for Martian Meteorite ALH84001

NASA Technical Reports Server (NTRS)

Mojzsis, Stephen J.

2000-01-01

We have studied the microdomain oxygen and carbon isotopic compositions by SIMS of complex carbonate rosettes from spinel therzolite xenoliths, hosted by nepheline basanite, from the island of Spitsbergen (Norway). The Quaternary volcanic rocks containing the xenoliths erupted into a high Arctic environment and through relatively thick continental crust containing carbonate rocks. We have attempted to constrain the sources of the carbonates in these rocks by combined O-18/O-16 and C-13/C-12 ratio measurements in 25 micron diameter spots of the carbonate and compare them to previous work based primarily on trace-element distributions. The origin of these carbonates can be interpreted in terms of either contamination by carbonate country rock during ascent of the xenoliths in the host basalt, or more probably by hydrothermal processes after emplacement. The isotopic composition of these carbonates from a combined delta.18O(sub SMOW) and delta.13C(sub PDB) standpoint precludes a primary origin of these minerals from the mantle. Here a description is given of the analysis procedure, standardization of the carbonates, major element compositions of the carbonates measured by electron microprobe, and their correlated C and O isotope compositions as measured by ion microprobe. Since these carbonate rosettes may represent a terrestrial analogue to the carbonate "globules" found in the martian meteorite ALH84001 interpretations for the origin of the features found in the Spitsbergen may be of interest in constraining the origin of these carbonate minerals on Mars.

Is carbon farming an effective climate mitigation option?

NASA Astrophysics Data System (ADS)

Zelikova, T. J.; Funk, J.; Deich, N.; Amador, G.; Jacobson, R.

2017-12-01

"Carbon farming" refers to agricultural and land management practices that store carbon in soils and biomass. Carbon-farming techniques can include crop rotation, cover crops, no-till practices, and the application of compost to build up soil organic matter. Carbon farming also improves agricultural production and sustainability, while mitigating climate change. Despite well-documented benefits of carbon farming, these practices continue to be underutilized outside of experimental settings. One barrier to the widespread use of carbon farming is the challenge of fitting these practices into ongoing commercial operations, while managing the consequent market uncertainties across the value chain. To help address this barrier, we are working with landowners and local groups to establish demonstration "test beds" that can build experience among land managers and help resolve market uncertainties. We specifically focus on demonstrating the commercial viability of management practices that can enhance soil health, catalyzing economic and environmental synergies that come from healthy soils. Each test bed has a commercial agricultural operation at its center, and we bring together researchers, local groups, corporate partners, and key policymakers who can support wider adoption of these agricultural techniques. Early challenges have included finding commercial farms willing to shift their practices and face uncertain outcomes. A transition to new practices usually involves changes in equipment, scheduling, activities, and monitoring that have implications for the entire farm operation, its resources, and its bottom line. At the same time, practitioners have difficulty quantifying the carbon benefits they provide, due to persistent uncertainties, even with the benefit of decades of experimental research. We are building a network of farmers who are implementing carbon farming practices and addressing these challenges, step by step. We envision our test beds becoming hubs that support a community of practitioners who can show the value of this work in real-world commercial operations, supported by rigorous science. By bringing together the necessary elements of each test bed, we aim to facilitate widespread integration of carbon storage activities into the agricultural sector.

Emission measurements from a crude oil tanker at sea.

PubMed

Agrawal, Harshit; Welch, William A; Miller, J Wayne; Cockert, David R

2008-10-01

This work presents an all-inclusive set of regulated and nonregulated emission factors for the main propulsion engine (ME), auxiliary engine (AE) and an auxiliary boiler on a Suezmax class tanker while operating at sea. The data include criteria pollutants (carbon monoxide, nitrogen oxides, sulfur oxides, and particulate matter), a greenhouse gas (carbon dioxide), the principal speciated hydrocarbons needed for human health risk assessments, and a detailed analysis of the PM into its primary constituents (ions, elements, organic, and elemental carbon). Measurements followed ISO 8178-1 methods with modifications described in the paper. The vessel burned two fuels: a heavy fuel oil in the ME and boiler and a distillate fuel in the AE. The weighted NO(x) emissions for the ME and AE are 19.87 +/- 0.95 and 13.57 +/- 0.31 g/kWh, respectively. The weighted PM mass emissions factor is 1.60 +/- 0.08 g/kWh for the ME and 0.141 +/- 0.005 g/kWh for the AE, with the sulfate content of the PM being the root cause for the difference. For the ME, sulfate with associated water is about 75% of total PM mass, and the organic carbon ranges from 15 to 25% of the PM mass. A deeper analysis showed that the conversion of fuel sulfur to sulfate in the ME ranged from 1.4to 5%. This article also provides emission factors for selected polycyclic aromatic hydrocarbons, heavy alkanes, carbonyls, light hydrocarbon species, metals, and ions for the ME, AE, and the boiler.

An aerosol climatology for a rapidly growing arid region (southern Arizona): Major aerosol species and remotely sensed aerosol properties

NASA Astrophysics Data System (ADS)

Sorooshian, Armin; Wonaschütz, Anna; Jarjour, Elias G.; Hashimoto, Bryce I.; Schichtel, Bret A.; Betterton, Eric A.

2011-10-01

This study reports a comprehensive characterization of atmospheric aerosol particle properties in relation to meteorological and back trajectory data in the southern Arizona region, which includes two of the fastest growing metropolitan areas in the United States (Phoenix and Tucson). Multiple data sets (MODIS, AERONET, OMI/TOMS, MISR, GOCART, ground-based aerosol measurements) are used to examine monthly trends in aerosol composition, aerosol optical depth (AOD), and aerosol size. Fine soil, sulfate, and organics dominate PM2.5 mass in the region. Dust strongly influences the region between March and July owing to the dry and hot meteorological conditions and back trajectory patterns. Because monsoon precipitation begins typically in July, dust levels decrease, while AOD, sulfate, and organic aerosol reach their maximum levels because of summertime photochemistry and monsoon moisture. Evidence points to biogenic volatile organic compounds being a significant source of secondary organic aerosol in this region. Biomass burning also is shown to be a major contributor to the carbonaceous aerosol budget in the region, leading to enhanced organic and elemental carbon levels aloft at a sky-island site north of Tucson (Mt. Lemmon). Phoenix exhibits different monthly trends for aerosol components in comparison with the other sites owing to the strong influence of fossil carbon and anthropogenic dust. Trend analyses between 1988 and 2009 indicate that the strongest statistically significant trends are reductions in sulfate, elemental carbon, and organic carbon, and increases in fine soil during the spring (March-May) at select sites. These results can be explained by population growth, land-use changes, and improved source controls.

Finite Element Simulation of Compression Molding of Woven Fabric Carbon Fiber/Epoxy Composites: Part I Material Model Development

DOE PAGES

Li, Yang; Zhao, Qiangsheng; Mirdamadi, Mansour; ...

2016-01-06

Woven fabric carbon fiber/epoxy composites made through compression molding are one of the promising choices of material for the vehicle light-weighting strategy. Previous studies have shown that the processing conditions can have substantial influence on the performance of this type of the material. Therefore the optimization of the compression molding process is of great importance to the manufacturing practice. An efficient way to achieve the optimized design of this process would be through conducting finite element (FE) simulations of compression molding for woven fabric carbon fiber/epoxy composites. However, performing such simulation remains a challenging task for FE as multiple typesmore » of physics are involved during the compression molding process, including the epoxy resin curing and the complex mechanical behavior of woven fabric structure. In the present study, the FE simulation of the compression molding process of resin based woven fabric composites at continuum level is conducted, which is enabled by the implementation of an integrated material modeling methodology in LS-Dyna. Specifically, the chemo-thermo-mechanical problem of compression molding is solved through the coupling of three material models, i.e., one thermal model for temperature history in the resin, one mechanical model to update the curing-dependent properties of the resin and another mechanical model to simulate the behavior of the woven fabric composites. Preliminary simulations of the carbon fiber/epoxy woven fabric composites in LS-Dyna are presented as a demonstration, while validations and models with real part geometry are planned in the future work.« less

Early diagenetic partial oxidation of organic matter and sulfides in the Middle Pennsylvanian (Desmoinesian) Excello Shale Member of the Fort Scott Limestone and equivalents, northern Midcontinent region, USA

USGS Publications Warehouse

Hatch, J.R.; Leventhal, M.S.

1997-01-01

A process of early diagenetic partial oxidation of organic matter and sulfides has altered the chemical composition of the Middle Pennsylvanian Excello Shale Member of the Fort Scott Limestone and equivalents in the northern Midcontinent region. This process was identified by comparison of organic carbon contents, Rock-Eval hydrogen indices, organic carbon ??13C and element compositions of core and surface mine samples of the Excello Shale Member with analyses of three other underlying and overlying organic-matter-rich marine shales (offshore shale lithofacies) from southern Iowa, northern Missouri, eastern Kansas and northeastern Oklahoma. The end product of the partial oxidation process is shale with relatively low contents of hydrogen-poor, C13-enriched organic matter, lower contents of sulfur and sulfide-forming elements, and relatively unchanged contents of phosphorus and many trace elements (e.g. Cr, Ni, and V). However, because of lower organic carbon contents, element/organic carbon ratios are greatly increased. The partial oxidation process apparently took place during subaerial exposure of the overlying marine carbonate member (Blackjack Creek Member of the Fort Scott Limestone) following a marine regression when meteoric waters percolated down to the level of the Excello muds allowing oxidation of organic matter and sulfides. This hypothesis is supported by earlier workers, who have identified meteoric carbonate cements within, and soil horizons at the top of the Blackjack Creek Member. The period of oxidation is constrained in that organic matter and sulfides in the Little Osage Shale Member of the Fort Scott Limestone and equivalents (immediately overlying the Blackjack Creek Member) appear unaltered. Similar alteration of other shales in the Middle and Upper Pennsylvanian sections may be local to regional in extent and would depend on the extent and duration of the marine regression and be influenced by local variations in permeability and topography. The partial oxidation process has likely led to a redistribution of sulfur and sulfide-forming elements into other organic-rich lithologies in the section. The altered/oxidized shales are nongenerative with respect to hydrocarbon generation.

Radioactive mineral spring precipitates, their analytical and statistical data and the uranium connection

USGS Publications Warehouse

Cadigan, R.A.; Felmlee, J.K.

1982-01-01

Major radioactive mineral springs are probably related to deep zones of active metamorphism in areas of orogenic tectonism. The most common precipitate is travertine, a chemically precipitated rock composed chiefly of calcium carbonate, but also containing other minerals. The mineral springs are surface manifestations of hydrothermal conduit systems which extend downward many kilometers to hot source rocks. Conduits are kept open by fluid pressure exerted by carbon dioxide-charged waters rising to the surface propelled by heat and gas (CO2 and steam) pressure. On reaching the surface, the dissolved carbon dioxide is released from solution, and calcium carbonate is precipitated. Springs also contain sulfur species (for example, H2S and HS-), and radon, helium and methane as entrained or dissolved gases. The HS- ion can react to form hydrogen sulfide gas, sulfate salts, and native sulfur. Chemical salts and native sulfur precipitate at the surface. The sulfur may partly oxidize to produce detectable sulfur dioxide gas. Radioactivity is due to the presence of radium-226, radon-222, radium-228, and radon-220, and other daughter products of uranium-238 and thorium-232. Uranium and thorium are not present in economically significant amounts in most radioactive spring precipitates. Most radium is coprecipitated at the surface with barite. Barite (barium sulfate) forms in the barium-containing spring water as a product of the oxidation of sulfur species to sulfate ions. The relatively insoluble barium sulfate precipitates and removes much of the radium from solution. Radium coprecipitates to a lesser extent with manganese-barium- and iron-oxy hydroxides. R-mode factor analysis of abundances of elements suggests that 65 percent of the variance of the different elements is affected by seven factors interpreted as follows: (1) Silica and silicate contamination and precipitation; (2) Carbonate travertine precipitation; (3) Radium coprecipitation; (4) Evaporite precipitation; (5) Hydrous limonite precipitation and coprecipitated elements including uranium; (6) Rare earth elements deposited with detrital contamination (?); (7) Metal carbonate adsorption and precipitation. Economically recoverable minerals occurring at some localities in spring precipitates are ores of iron, manganese, sulfur, tungsten and barium and ornamental travertine. Continental radioactive mineral springs occur in areas of crustal thickening caused by overthrusting of crustal plates, and intrusion and metamorphism. Sedimentary rocks on the lower plate are trapped between the plates and form a zone of metamorphism. Connate waters, carbonate rocks and organic-carbon-bearing rocks react to extreme pressure and temperature to produce carbon dioxide, and steam. Fractures are forced open by gas and fluid pressures. Deep-circulating meteoric waters then come in contact with the reactive products, and a hydrothermal cell forms. When hot mineral-charged waters reach the surface they form the familiar hot mineral springs. Hot springs also occur in relation to igneous intrusive action or volcanism both of which may be products of the crustal plate overthrusting. Uranium and thorium in the sedimentary rocks undergoing metamorphism are sometimes mobilized, but mobilization is generally restricted to an acid hydrothermal environment; much is redeposited in favorable environments in the metamorphosed sediments. Radium and radon, which are highly mobile in both acid and alkaline aqueous media move upward into the hydrothermal cell and to the surface.

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.

Origin of enormous trace metal enrichments in weathering mantles of Jurassic carbonates: evidence from Sr, Nd and Pb isotopes

NASA Astrophysics Data System (ADS)

Hissler, C.; Stille, P.; Juilleret, J.; Iffly, J.; Perrone, T.; Morvan, G.

2013-12-01

Weathering mantels are widespread worldwide and include lateritic, sandy and kaolinite-rich saprolites and residuals of partially dissolved carbonate rocks. These old regolith systems have a complex history of formation and may present a polycyclic evolution due to successive geological and pedogenetic processes that affected the profile. Until now, only few studies highlighted the unusual content of associated trace elements in this type of weathering mantle. For instance, these enrichments can represent about five times the content of the underlying Bajocian to Oxfordian limestone/marl complexes, which have been relatively poorly studied compared to weathering mantle developed on magmatic bedrocks. Up to now, neither soil, nor saprolite formation has to our knowledge been geochemically elucidated. Therefore, the aim of this study was to examine more closely the soil forming dynamics and the relationship of the chemical soil composition to potential sources (saprolite, Bajocian silty marls and limestones, atmospheric particles deposition...). Of special interest has also been the origin of trace metals and the processes causing their enrichments. Especially Rare Earth Element (REE) distribution patterns and Sr, Nd and Pb isotope ratios are particularly well suited to identify trace element migration, to recognize origin and mixing processes and, in addition, to decipher possible anthropogenic and/or "natural" atmosphere-derived contributions to the soil. Moreover, leaching experiments shall help to identify mobile phases in the soil system. This may inform on the stability of trace elements and especially on their behaviour in these Fe-enriched carbonate systems. Trace metal migration and enrichments were studied on a cambisol developing on an underlying Jurassic limestone. The base is strongly enriched among others in rare earth elements (ΣREE: 2640ppm) or redox-sensitive elements such as Fe (44 wt.%), V (920ppm), Cr (700ppm), Zn (550ppm), As (260ppm), Co (45ppm) and Cd (2.4ppm). The underlying limestone and marl show, compared to average world carbonates, enrichments in the same elements and trace element distribution patterns similar to the soil suggesting their close genetic relationship. Pb, Sr and Nd isotope data allow to identify three principal components in the soil: a silicate-rich phase at close to the surface, a strongly trace metal enriched component at the bottom of the soil profile and an anthropogenic, atmosphere- derived component detected in the soil leachates. The isotopic mixing curves defined by the soil samples point to the close genetic connection between upper and lowermost soil horizons. The Nd isotopic composition of the leachates of all soil horizons are in contrast to the untreated soil and residual soil samples very homogeneous suggesting that the leachable phases of the upper and lower soil horizons are genetically connected. The downward migration of the trace metals is stopped at this soil level due to the presence of important secondary calcite precipitations, smectite and Fe-oxide accumulations. Mass balance calculations indicate that the enrichment process goes along with a volume increase relative to the bottom soil horizons.

Advanced Survivable Radiator Development Program

DTIC Science & Technology

1993-03-01

pyrolytic process. The ceramic fiber is amorphous with a typical elemental composition of 57% silicon, 28% nitrogen, 10% carbon , and 4% oxygen, and has an...exist: Optimum choice dependent on mission, operational requirements, and threat environment Configurations: Fibers , Rods, Fins Carbon - Carbon e ASpecial... Carbon Fiber Area Density ,,,--Stainless Aluminum Be Diamond BC Bond Copper Weave: Be, Al, SS. Ti, Nitinol Configurations: Low Z or High Z. depending

The review of recent carbonate minerals processing technology

NASA Astrophysics Data System (ADS)

Solihin

2018-02-01

Carbonate is one of the groups of minerals that can be found in relatively large amount in the earth crust. The common carbonate minerals are calcium carbonate (calcite, aragonite, depending on its crystal structure), magnesium carbonate (magnesite), calcium-magnesium carbonate (dolomite), and barium carbonate (barite). A large amount of calcite can be found in many places in Indonesia such as Padalarang, Sukabumi, and Tasikmalaya (West Java Provence). Dolomite can be found in a large amount in Gresik, Lamongan, and Tuban (East Java Provence). Magnesite is quite rare in Indonesia, and up to the recent years it can only be found in Padamarang Island (South East Sulawesi Provence). The carbonate has been being exploited through open pit mining activity. Traditionally, calcite can be ground to produce material for brick production, be carved to produce craft product, or be roasted to produce lime for many applications such as raw materials for cement, flux for metal smelting, etc. Meanwhile, dolomite has traditionally been used as a raw material to make brick for local buildings and to make fertilizer for coconut oil plant. Carbonate minerals actually consist of important elements needed by modern application. Calcium is one of the elements needed in artificial bone formation, slow release fertilizer synthesis, dielectric material production, etc. Magnesium is an important material in automotive industry to produce the alloy for vehicle main parts. It is also used as alloying element in the production of special steel for special purpose. Magnesium oxide can be used to produce slow release fertilizer, catalyst and any other modern applications. The aim of this review article is to present in brief the recent technology in processing carbonate minerals. This review covers both the technology that has been industrially proven and the technology that is still in research and development stage. One of the industrially proven technologies to process carbonate mineral is the production of magnesium metals from dolomite. The discussion is emphasized to the requirements of certain aspects prior to the application of this technology in Indonesia. Other technologies that are still in research and development stage are also presented and discussed. The discussion is aimed to find further possible research and development in carbonate processing.

Elements, Compounds & Mixtures. Physical Science in Action[TM]. Schlessinger Science Library. [Videotape].

ERIC Educational Resources Information Center

2000

The world contains a limited number of elements--the purest form of matter. But when these elements are combined, the possibilities are limitless! Water, carbon dioxide and salt are just a few examples of how elements can be combined to form entirely new substances. Many of these combinations occur naturally, while others are man-made. Students…

Development of processing techniques for advanced thermal protection materials

NASA Technical Reports Server (NTRS)

Selvaduray, Guna S.

1995-01-01

The main purpose of this work has been in the development and characterization of materials for high temperature applications. Thermal Protection Systems (TPS) are constantly being tested, and evaluated for increased thermal shock resistance, high temperature dimensional stability, and tolerance to environmental effects. Materials development was carried out through the use of many different instruments and methods, ranging from extensive elemental analysis to physical attributes testing. The six main focus areas include: (1) protective coatings for carbon/carbon composites; (2) TPS material characterization; (3) improved waterproofing for TPS; (4) modified ceramic insulation for bone implants; (5) improved durability ceramic insulation blankets; and (6) ultra-high temperature ceramics. This report describes the progress made in these research areas during this contract period.

Geochemical constraints on the origin of Doushantuo cap carbonates in the Yangtze Gorges area, South China

NASA Astrophysics Data System (ADS)

Wang, Qinxian; Lin, Zhijia; Chen, Duofu

2014-05-01

Marinoan cap carbonates have been suggested to be primarily deposited in glacial meltwater and upwelled seawater. However, elemental geochemistry evidence for this depositional model is lacking. Here, we report high-spatial-resolution measurements of major, trace and rare earth elements of the Doushantuo cap carbonates from the Jiulongwan section in the Yangtze Gorges area, South China. Our results show that: 1) the basal cap carbonates display slight MREE enrichment, weak positive La anomalies, near-chondritic Y/Ho ratios, and slight negative Ce anomalies; 2) the lower-middle cap carbonates show slight LREE depletion or MREE enrichment, weak positive La and Eu anomalies, supra-chondritic Y/Ho ratios, and slight negative Ce anomalies; 3) the upper-middle cap carbonates have consistent enrichment of P, Fe, and trace metals, slight LREE depletion, and weak positive Ce, La and Eu anomalies; and 4) the upper cap carbonates exhibit LREE enrichment, weak positive La and Eu anomalies, supra-chondritic Y/Ho ratios, and mild negative Ce anomalies. These findings indicate that the Doushantuo cap carbonates did not precipitate from normal contemporaneous seawater, rather, the basal cap carbonates were deposited in oxygenated, relatively pure deglacial meltwater; the lower-middle cap carbonates in oxygenated brackish water; the upper-middle cap carbonates in upwelled anoxic brine water; and the upper cap carbonates in oxygenated brackish water. Our depositional model is consistent with the proposed sequence of events after the meltdown of Marinoan glaciation by Shields (2005).

Oxidation corrosion resistant superalloys and coatings

NASA Technical Reports Server (NTRS)

Jackson, Melvin R. (Inventor); Rairden, III, John R. (Inventor)

1978-01-01

An article of manufacture having improved high temperature oxidation and corrosion resistance comprising: (a) a superalloy substrate containing a carbide reinforcing phase, and (b) a coating consisting of chromium, aluminum, carbon, at least one element selected from iron, cobalt or nickel, and optionally an element selected from yttrium or the rare earth elements.

Oxidation corrosion resistant superalloys and coatings

NASA Technical Reports Server (NTRS)

Jackson, Melvin R. (Inventor); Rairden, III, John R. (Inventor)

1980-01-01

An article of manufacture having improved high temperature oxidation and corrosion resistance comprising: (a) a superalloy substrate containing a carbide reinforcing phase, and (b) a coating consisting of chromium, aluminum, carbon, at least one element selected from iron, cobalt or nickel, and optionally an element selected from yttrium or the rare earth elements.

Near-road sampling of PM2. 5, BC, and fine-particle chemical components in Kathmandu Valley, Nepal

NASA Astrophysics Data System (ADS)

Shakya, Kabindra M.; Rupakheti, Maheswar; Shahi, Anima; Maskey, Rejina; Pradhan, Bidya; Panday, Arnico; Puppala, Siva P.; Lawrence, Mark; Peltier, Richard E.

2017-06-01

Semicontinuous PM2. 5 and black carbon (BC) concentrations, and 24 h integrated PM2. 5 filter samples were collected near roadways in the Kathmandu Valley, Nepal. Instruments were carried by a group of volunteer traffic police officers in the vicinity of six major roadway intersections in the Kathmandu Valley across two sampling periods in 2014. Daily PM2. 5 filter samples were analyzed for water-soluble inorganic ions, elemental carbon (EC) and organic carbon (OC), and 24 elements. Mean PM2. 5 and BC concentrations were 124.76 µg m-3 and 16.74 µgC m-3 during the drier spring sampling period, and 45.92 µg m-3 and 13.46 µgC m-3 during monsoonal sampling. Despite the lower monsoonal PM2. 5 concentrations, BC and several elements were not significantly lower during the monsoon, which indicates an important contribution of vehicle-related emissions throughout both seasons in this region. During the monsoon, there was an enhanced contribution of chemical species (elements and water-soluble inorganic ions), except secondary inorganic ions, and BC to PM2. 5 (crustal elements: 19 %; heavy metals: 5 %; and BC: 39 %) compared to those in spring (crustal elements: 9 %; heavy metals: 1 %; and BC: 18 %). Silica, calcium, aluminum, and iron were the most abundant elements during both spring and the monsoon, with total concentrations of 12.13 and 8.85 µg m-3, respectively. PM2. 5 and BC showed less spatial variation compared to that for individual chemical species.

Green synthesis of nitrogen-doped graphitic carbon sheets with use of Prunus persica for supercapacitor applications

NASA Astrophysics Data System (ADS)

Atchudan, Raji; Edison, Thomas Nesakumar Jebakumar Immanuel; Perumal, Suguna; Lee, Yong Rok

2017-01-01

Nitrogen-doped graphitic carbon sheets (N-GCSs) were prepared from the extract of unripe Prunus persica fruit by a direct hydrothermal method. The synthesized N-GCSs were examined by high resolution transmission electron microscopy (HRTEM), nitrogen adsorption-desorption isotherms, X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared (FT-IR) spectroscopy. HRTEM showed that the synthesized carbon sheets were graphitic with lattice fringes and an inter-layer distance of 0.36 nm. Doping with the nitrogen moiety present over the synthesized GCSs was confirmed by XPS, FT-IR spectroscopy, and energy dispersive X-ray spectroscopy elemental mapping. The fruit extract associated with hydrothermal-carbonization method is economical and eco-friendly with a single step process. The resulting carbon sheets could be modified and are promising candidates for nano-electronic applications, including supercapacitors. The synthesized N-GCSs-2 provided a high specific capacitance of 176 F g-1 at a current density of 0.1 A g-1. This electrode material has excellent cyclic stability, even after 2000 cycles of charge-discharge at a current density of 0.5 A g-1.

Effect of Secondary Cooling Conditions on Solidification Structure and Central Macrosegregation in Continuously Cast High-Carbon Rectangular Billet

NASA Astrophysics Data System (ADS)

Zeng, Jie; Chen, Weiqing

2015-10-01

Solidification structures of high carbon rectangular billet with a size of 180 mm × 240 mm in different secondary cooling conditions were simulated using cellular automaton-finite element (CAFE) coupling model. The adequacy of the model was compared with the simulated and the actual macrostructures of 82B steel. Effects of the secondary cooling water intensity on solidification structures including the equiaxed grain ratio and the equiaxed grain compactness were discussed. It was shown that the equiaxed grain ratio and the equiaxed grain compactness changed in the opposite direction at different secondary cooling water intensities. Increasing the secondary cooling water intensity from 0.9 or 1.1 to 1.3 L/kg could improve the equiaxed grain compactness and decrease the equiaxed grain ratio. Besides, the industrial test was conducted to investigate the effect of different secondary cooling water intensities on the center carbon macrosegregation of 82B steel. The optimum secondary cooling water intensity was 0.9 L/kg, while the center carbon segregation degree was 1.10. The relationship between solidification structure and center carbon segregation was discussed based on the simulation results and the industrial test.

Mass concentration, composition and sources of fine and coarse particulate matter in Tijuana, Mexico, during Cal-Mex campaign

NASA Astrophysics Data System (ADS)

Minguillón, María Cruz; Campos, Arturo Alberto; Cárdenas, Beatriz; Blanco, Salvador; Molina, Luisa T.; Querol, Xavier

2014-05-01

This work was carried out in the framework of the Cal-Mex project, which focuses on investigating the atmosphere along Mexico-California border region. Sampling was carried out at two sites located in Tijuana urban area: Parque Morelos and Metales y Derivados. PM2.5 and PM10 24 h samples were collected every three days from 17th May 2010 to 27th June 2010, and were used for gravimetric and chemical analyses (major and minor elements, inorganic ions, organic and elemental carbon) of PM. A subsequent Positive Matrix Factorization (PMF) analysis was performed. PM2.5 and PM10 average concentrations during Cal-Mex were relatively lower compared to usual annual averages. Trace elements concentrations recorded in the present study were lower than those recorded in Mexico City in 2006, with the exception of Pb at Metales y Derivados, attributed to the influence of a specific industrial source, which also includes As, Cd and Tl. Apart from this industrial source, both urban sites were found to be affected by similar sources with respect to bulk PM. Fine PM (PM2.5) was mainly apportioned by fueloil and biomass combustion and secondary aerosols, and road traffic. Coarse PM (PM2.5-10) was mainly apportioned by a mineral source (sum of road dust resuspension, construction emissions and natural soil) and fresh and aged sea salt. The road traffic was responsible for more than 60% of the fine elemental carbon and almost 40% of the fine organic matter.

Carbonates of the Gunflint Banded Iron Formation as Analogs of Martian Carbonates

NASA Technical Reports Server (NTRS)

Pun, A.; Papike, J. J.; Shearer, C. K.

2001-01-01

Terrestrial iron formations preserve remnants of life on Earth and may serve as analogs for identifying evidence of biologic activity in martian rocks. We report on the petrography, mineralogy and trace-element abundances of carbonates of the Gunflint banded iron formation. Additional information is contained in the original extended abstract.

The transformation of inorganic sulfur compounds and the assimilation of organic and inorganic carbon by the sulfur disproportionating bacterium Desulfocapsa sulfoexigens.

PubMed

Frederiksen, Trine-Maria; Finster, Kai

2004-02-01

The physiology of the sulfur disproportionator Desulfocapsa sulfoexigens was investigated in batch cultures and in a pH-regulated continuously flushed fermentor system. It was shown that a sulphide scavanger in the form of ferric iron was not obligatory and that the control of pH allowed production of more biomass than was possible in carbonate buffered but unregulated batch cultures. Small amounts of sulphite were produced during disproportionation of elemental sulfur and thiosulphate. In addition, it was shown that in the presence of hydrogen, a respiratory type of process is favored before the disproportionation of sulphite, thiosulphate and elemental sulfur. Sulphate reduction was not observed. D. sulfoexigens assimilated inorganic carbon even in the presence of organic carbon sources. Inorganic carbon assimilation was probably catalyzed by the reverse CO-dehydrogenase pathway, which was supported by the constitutive expression of the gene encoding CO-dehydrogenase in cultures grown in the presence of acetate and by the high carbon fractionation values that are indicative of this pathway.

Regional patterns of labile organic carbon flux in North American Arctic Margin (NAAM) as reflected by redox sensitive-elements distributions in sediments

NASA Astrophysics Data System (ADS)

Gobeil, C.; Kuzyk, Z. Z. A.; Goni, M. A.; Macdonald, R. W.

2016-02-01

Concentrations of elements (S, Mn, Mo, U, Cd, Re) providing insights on organic C metabolized through oxidative processes at the sea floor were measured in 27 sediment cores collected along a section extending from the North Bering Sea to Davis Strait via the Canadian Archipelago. Sedimentary distributions and accumulation rates of these elements were used to i) document the relative importance of aerobic versus anaerobic degradation of organic C in NAAM sediments, ii) infer variations in water column carbon flux and iii) estimate the importance of this margin as a sink for key elements in the Arctic and global ocean. Distributions of Mn, total S and reduced inorganic S demonstrated that most sediments along the NAAM had relatively thick (>1 cm) surface oxic layers, underlain by sediments with weakly reducing conditions and limited sulphate reduction. Strongly reducing conditions accompanied by substantial sedimentary pyrite burial occurred only in certain subregions, including the Bering-Chukchi Shelves, shallow portions of Barrow Canyon. Estimated accumulation rates of authigenic S, Mo, Cd and U, and total Re displayed marked spatial variability that was related to sedimentary redox conditions induced by the supply of labile C to the seabed, as shown by significant relationships between the accumulation rates and vertical C flux, estimated from regional primary production values and water depth at the coring sites. High primary production combined with shallow water columns drive elevated rates of authigenic trace element accumulation in sediments from the Bering-Chukchi Shelves whereas low production combined with moderately deep conditions drive low rates of accumulation in sediments in the Beaufort Shelf, Davis Strait and Canadian Archipelago. Using the average authigenic trace element accumulation rates in sediments from the various regions, we submit that the shelves along the NAAM margin are important sinks in global marine biogeochemical budgets.

Simulated Nitrogen Deposition has Minor Effects on Ecosystem Pools and Fluxes of Energy, Elements, and Biochemicals in a Northern Hardwoods Forest

NASA Astrophysics Data System (ADS)

Talhelm, A. F.; Pregitzer, K. S.; Burton, A. J.; Xia, M.; Zak, D. R.

2017-12-01

The elemental and biochemical composition of plant tissues is an important influence on primary productivity, decomposition, and other aspects of biogeochemistry. Human activity has greatly altered biogeochemical cycles in ecosystems downwind of industrialized regions through atmospheric nitrogen deposition, but most research on these effects focuses on individual elements or steps in biogeochemical cycles. Here, we quantified pools and fluxes of biomass, the four major organic elements (carbon, oxygen, hydrogen, nitrogen), four biochemical fractions (lignin, structural carbohydrates, cell walls, and soluble material), and energy in a mature northern hardwoods forest in Michigan. We sampled the organic and mineral soil, fine and coarse roots, leaf litter, green leaves, and wood for chemical analyses. We then combined these data with previously published and archival information on pools and fluxes within this forest, which included replicated plots receiving either ambient deposition or simulated nitrogen deposition (3 g N m-2 yr-1 for 18 years). Live wood was the largest pool of energy and all elements and biochemical fractions. However, the production of wood, leaf litter, and fine roots represented similar fluxes of carbon, hydrogen, oxygen, cell wall material, and energy, while nitrogen fluxes were dominated by leaf litter and fine roots. Notably, the flux of lignin via fine roots was 70% higher than any other flux. Experimental nitrogen deposition had relatively few significant effects, increasing foliar nitrogen, increasing the concentration of lignin in the soil organic horizon and decreasing pools of all elements and biochemical fractions in the soil organic horizon except nitrogen, lignin, and structural carbohydrates. Overall, we found that differences in tissue chemistry concentrations were important determinants of ecosystem-level pools and fluxes, but that nitrogen deposition had little effect on concentrations, pools, or fluxes in this mature forest. Disclaimer: The views expressed in this poster are those of the authors and do not necessarily represent the views or policies of the U.S. EPA.

Summary of water-quality data for City of Albuquerque drinking-water supply wells, 1988-97

USGS Publications Warehouse

Bexfield, Laura M.; Lindberg, William E.; Anderholm, Scott K.

1999-01-01

The City of Albuquerque has collected and analyzed more than 5,000 water-quality samples from 113 water-supply wells in the Albuquerque area, including many drinking-water supply wells, since May of 1988. As a result, a large water-quality data base has been compiled that includes data for major ions, nutrients, trace elements, carbon, volatile organic compounds, radiological constituents, and bacteria. These data are intended to improve the understanding and management of the ground-water resources of the region, rather than demonstrate compliance with Federal and State drinking-water standards. This report gives summary statistics for selected physical properties and chemical constituents for ground water from wells used by the City of Albuquerque for drinking-water supply between 1988 and 1997. Maps are provided to show the general spatial distribution of selected parameters and water types around the region. Although the values of some parameters vary substantially across the city, median values for all parameters included in this report are less than their respective maximum contaminant levels in each drinking-water supply well. The dominant water types are sodium plus potassium / carbonate plus bicarbonate in the western part of the city and calcium / carbonate plus bicarbonate in the eastern part of the city.

Chemistry between the stars.

PubMed

Irvine, W M

1987-01-01

Life--as we know it--is a chemical process, based on water and carbon compounds. Complex organic molecules are made primarily from the biogenic elements--carbon, hydrogen, nitrogen, oxygen, phosphorus and sulfur--that formed deep within massive ancient stars. How did these elements travel from their stellar birthplaces across time and space to make up the life-form that is reading these words? In this article, we'll take a look at the chemical processes that set the stage for the origin of life.

Synthesis of Tetraphenylstannacyclopentadienes (Stannoles). II. Derivatives and Adducts of 1,1-Dihalo-2,3,4,5-tetraphenylstannoles.

DTIC Science & Technology

1981-04-15

products (4-bromo-l,2,3,4-tetraphenylbutadienyl)tin tribromide o (4-iodo-l,2,3,4-tetraphenylbutadienyl)tin triiodide. Even gentle chlorination of...hexaphenyistannole by elemental chlorine cleaves the ring tin-carbon bonds to form cis-cis-l ,4-dichloro-l ,2 ,3 ,4-tetraphenylbutadiene-l, 3 and diphenyltin... chlorination of hexaphenylstannole by elemental chlorine cleaves the ring tin-carbon bonds to form cis- cis-l,4-dichloro-l,2,3,4-tetraphenylbutadiene-1,3

Carbon sequestration potential and physicochemical properties differ between wildfire charcoals and slow-pyrolysis biochars.

PubMed

Santín, Cristina; Doerr, Stefan H; Merino, Agustin; Bucheli, Thomas D; Bryant, Rob; Ascough, Philippa; Gao, Xiaodong; Masiello, Caroline A

2017-09-11

Pyrogenic carbon (PyC), produced naturally (wildfire charcoal) and anthropogenically (biochar), is extensively studied due to its importance in several disciplines, including global climate dynamics, agronomy and paleosciences. Charcoal and biochar are commonly used as analogues for each other to infer respective carbon sequestration potentials, production conditions, and environmental roles and fates. The direct comparability of corresponding natural and anthropogenic PyC, however, has never been tested. Here we compared key physicochemical properties (elemental composition, δ 13 C and PAHs signatures, chemical recalcitrance, density and porosity) and carbon sequestration potentials of PyC materials formed from two identical feedstocks (pine forest floor and wood) under wildfire charring- and slow-pyrolysis conditions. Wildfire charcoals were formed under higher maximum temperatures and oxygen availabilities, but much shorter heating durations than slow-pyrolysis biochars, resulting in differing physicochemical properties. These differences are particularly relevant regarding their respective roles as carbon sinks, as even the wildfire charcoals formed at the highest temperatures had lower carbon sequestration potentials than most slow-pyrolysis biochars. Our results challenge the common notion that natural charcoal and biochar are well suited as proxies for each other, and suggest that biochar's environmental residence time may be underestimated when based on natural charcoal as a proxy, and vice versa.

Modeling the Dynamics and Export of Dissolved Organic Matter in the Northeastern U.S. Continental Shelf

NASA Technical Reports Server (NTRS)

Druon, J.N.; Mannino, A.; Signorini, Sergio R.; McClain, Charles R.; Friedrichs, M.; Wilkin, J.; Fennel, K.

2009-01-01

Continental shelves are believed to play a major role in carbon cycling due to their high productivity. Particulate organic carbon (POC) burial has been included in models as a carbon sink, but we show here that seasonally produced dissolved organic carbon (DOC) on the shelf can be exported to the open ocean by horizontal transport at similar rates (1-2 mol C/sq m/yr) in the southern U.S. Mid-Atlantic Bight (MAB). The dissolved organic matter (DOM) model imbedded in a coupled circulation-biogeochemical model reveals a double dynamics: the progressive release of dissolved organic nitrogen (DON) in the upper layer during summer increases the regenerated primary production by 30 to 300%, which, in turns ; enhances the DOC production mainly from phytoplankton exudation in the upper layer and solubilization of particulate organic matter (POM) deeper in the water column. This analysis suggests that DOM is a key element for better representing the ecosystem functioning and organic fluxes in models because DOM (1) is a major organic pool directly related to primary production, (2) decouples partially the carbon and nitrogen cycles (through carbon excess uptake, POM solubilization and DOM mineralization) and (3) is intimately linked to the residence time of water masses for its distribution and export.

Geant4 simulation of clinical proton and carbon ion beams for the treatment of ocular melanomas with the full 3-D pencil beam scanning system

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

Farina, Edoardo; Riccardi, Cristina; Rimoldi, Adele

This work investigates the possibility to use carbon ion beams delivered with active scanning modality, for the treatment of ocular melanomas at the Centro Nazionale di Adroterapia Oncologica (CNAO) in Pavia. The radiotherapy with carbon ions offers many advantages with respect to the radiotherapy with protons or photons, such as a higher relative radio-biological effectiveness (RBE) and a dose release better localized to the tumor. The Monte Carlo (MC) Geant4 10.00 patch-03 toolkit is used to reproduce the complete CNAO extraction beam line, including all the active and passive components characterizing it. The simulation of proton and carbon ion beamsmore » and radiation scanned field is validated against CNAO experimental data. For the irradiation study of the ocular melanoma an eye-detector, representing a model of a human eye, is implemented in the simulation. Each element of the eye is reproduced with its chemical and physical properties. Inside the eye-detector a realistic tumor volume is placed and used as the irradiation target. A comparison between protons and carbon ions eye irradiations allows to study possible treatment benefits if carbon ions are used instead of protons. (authors)« less

Mechanical testing and modelling of carbon-carbon composites for aircraft disc brakes

NASA Astrophysics Data System (ADS)

Bradley, Luke R.

The objective of this study is to improve the understanding of the stress distributions and failure mechanisms experienced by carbon-carbon composite aircraft brake discs using finite element (FE) analyses. The project has been carried out in association with Dunlop Aerospace as an EPSRC CASE studentship. It therefore focuses on the carbon-carbon composite brake disc material produced by Dunlop Aerospace, although it is envisaged that the approach will have broader applications for modelling and mechanical testing of carbon-carbon composites in general. The disc brake material is a laminated carbon-carbon composite comprised of poly(acrylonitrile) (PAN) derived carbon fibres in a chemical vapour infiltration (CVI) deposited matrix, in which the reinforcement is present in both continuous fibre and chopped fibre forms. To pave the way for the finite element analysis, a comprehensive study of the mechanical properties of the carbon-carbon composite material was carried out. This focused largely, but not entirely, on model composite materials formulated using structural elements of the disc brake material. The strengths and moduli of these materials were measured in tension, compression and shear in several orientations. It was found that the stress-strain behaviour of the materials were linear in directions where there was some continuous fibre reinforcement, but non-linear when this was not the case. In all orientations, some degree of non-linearity was observed in the shear stress-strain response of the materials. However, this non-linearity was generally not large enough to pose a problem for the estimation of elastic moduli. Evidence was found for negative Poisson's ratio behaviour in some orientations of the material in tension. Additionally, the through-thickness properties of the composite, including interlaminar shear strength, were shown to be positively related to bulk density. The in-plane properties were mostly unrelated to bulk density over the range of densities of the tested specimens.Two types of FE model were developed using a commercially available program. The first type was designed to analyse the model composite materials for comparison with mechanical test data for the purpose of validation of the FE model. Elastic moduli predicted by this type of FE model showed good agreement with the experimentally measured elastic moduli of the model composite materials. This result suggested that the use of layered FE models, which rely upon an isostrain assumption between the layers, can be useful in predicting the elastic properties of different lay-ups of the disc brake material.The second type of FE model analysed disc brake segments, using the experimentally measured bulk mechanical properties of the disc brake material. This FE model approximated the material as a continuum with in-plane isotropy but with different properties in the through-thickness direction. In order to validate this modelling approach, the results of the FE analysis were compared with mechanical tests on disc brake segments, which were loaded by their drive tenons in a manner intended to simulate in-service loading. The FE model showed good agreement with in-plane strains measured on the disc tenon face close to the swept area of the disc, but predicted significantly higher strains than those experimentally measured on the tenon fillet curve. This discrepancy was attributed to the existence of a steep strain gradient on the fillet curve.

Carbon kagome lattice and orbital-frustration-induced metal-insulator transition for optoelectronics.

PubMed

Chen, Yuanping; Sun, Y Y; Wang, H; West, D; Xie, Yuee; Zhong, J; Meunier, V; Cohen, Marvin L; Zhang, S B

2014-08-22

A three-dimensional elemental carbon kagome lattice, made of only fourfold-coordinated carbon atoms, is proposed based on first-principles calculations. Despite the existence of 60° bond angles in the triangle rings, widely perceived to be energetically unfavorable, the carbon kagome lattice is found to display exceptional stability comparable to that of C(60). The system allows us to study the effects of triangular frustration on the electronic properties of realistic solids, and it demonstrates a metal-insulator transition from that of graphene to a direct gap semiconductor in the visible blue region. By minimizing s-p orbital hybridization, which is an intrinsic property of carbon, not only the band edge states become nearly purely frustrated p states, but also the band structure is qualitatively different from any known bulk elemental semiconductors. For example, the optical properties are similar to those of direct-gap semiconductors GaN and ZnO, whereas the effective masses are comparable to or smaller than those of Si.

Prediction of Elastic Constants of the Fuzzy Fibre Reinforced Polymer Using Computational Micromechanics

NASA Astrophysics Data System (ADS)

Pawlik, Marzena; Lu, Yiling

2018-05-01

Computational micromechanics is a useful tool to predict properties of carbon fibre reinforced polymers. In this paper, a representative volume element (RVE) is used to investigate a fuzzy fibre reinforced polymer. The fuzzy fibre results from the introduction of nanofillers in the fibre surface. The composite being studied contains three phases, namely: the T650 carbon fibre, the carbon nanotubes (CNTs) reinforced interphase and the epoxy resin EPIKOTE 862. CNTs are radially grown on the surface of the carbon fibre, and thus resultant interphase composed of nanotubes and matrix is transversely isotropic. Transversely isotropic properties of the interphase are numerically implemented in the ANSYS FEM software using element orientation command. Obtained numerical predictions are compared with the available analytical models. It is found that the CNTs interphase significantly increased the transverse mechanical properties of the fuzzy fibre reinforced polymer. This extent of enhancement changes monotonically with the carbon fibre volume fraction. This RVE model enables to investigate different orientation of CNTs in the fuzzy fibre model.

Trace elements in streambed sediments of small subtropical streams on O'ahu, Hawai'i: Results from the USGS NAWQA program

USGS Publications Warehouse

De Carlo, E. H.; Tomlinson, M.S.; Anthony, S.S.

2005-01-01

Data are presented for trace element concentrations determined in the <63 ??m fraction of streambed sediment samples collected at 24 sites on the island of O'ahu, Hawai'i. Sampling sites were classified as urban, agricultural, mixed (urban/agricultural), or forested based on their dominant land use, although the mixed land use at selected sampling sites consisted of either urban and agricultural or forested and agricultural land uses. Forest dominated sites were used as reference sites for calculating enrichment factors. Trace element concentrations were compared to concentrations from studies conducted in the conterminous United States using identical methods and to aquatic-life guidelines provided by the Canadian Council of Ministers of the Environment. A variety of elements including Pb, Cr, Cu and Zn exceeded the aquatic-life guidelines in selected samples. All of the Cr and Zn values and 16 of 24 Cu values exceeded their respective guidelines. The potential toxicity of elements exceeding guidelines, however, should be considered in the context of strong enrichments of selected trace elements attributable to source rocks in Hawai'i, as well as in the context of the abundance of fine-grained sediment in the streambed of O'ahu streams. Statistical methods including cluster analysis, Kruskal-Wallis non-parametric test, correlation analysis, and principal component analysis (PCA) were used to evaluate differences and elucidate relationships between trace elements and sites. Overall, trace element distributions and abundances can be correlated to three principal sources of elements. These include basaltic rocks of the volcanic edifice (Fe, Al, Ni, Co, Cr, V and Cu), carbonate/seawater derived elements (Mg, Ca, Na and Sr), and elements enriched owing to anthropogenic activity (P, Sn, Cd, Sn, Ba and Pb). Anthropogenic enrichment gradients were observed for Ba, Cd, Pb, Sn and Zn in the four streams in which sediments were collected upstream and downstream. The findings of this study are generally similar to but differ slightly from previous work on sediments and suspended particulate matter in streams, from two urban watersheds of O'ahu, Hawai'i. Inter-element associations in the latter were often stronger and indicated a mixture of anthropogenic, agricultural and basaltic sources of trace elements. Some elements fell into different statistical categories in the two studies, owing in part to differences in study design and the hydrogeological constraints on the respective study areas.

Analysis of Transformation Plasticity in Steel Using a Finite Element Method Coupled with a Phase Field Model

PubMed Central

Cho, Yi-Gil; Kim, Jin-You; Cho, Hoon-Hwe; Cha, Pil-Ryung; Suh, Dong-Woo; Lee, Jae Kon; Han, Heung Nam

2012-01-01

An implicit finite element model was developed to analyze the deformation behavior of low carbon steel during phase transformation. The finite element model was coupled hierarchically with a phase field model that could simulate the kinetics and micro-structural evolution during the austenite-to-ferrite transformation of low carbon steel. Thermo-elastic-plastic constitutive equations for each phase were adopted to confirm the transformation plasticity due to the weaker phase yielding that was proposed by Greenwood and Johnson. From the simulations under various possible plastic properties of each phase, a more quantitative understanding of the origin of transformation plasticity was attempted by a comparison with the experimental observation. PMID:22558295

Changes in composition and porosity occurring during the thermal degradation of wood and wood components

USGS Publications Warehouse

Rutherford, David W.; Wershaw, Robert L.; Cox, Larry G.

2005-01-01

Samples of pine and poplar wood, pine bark, and purified cellulose and lignin were charred at temperatures ranging from 250?C to 500?C for times ranging from 1 hour to 168 hours. Changes in composition were examined by Fourier Transform Infrared (FTIR) and 13C Nuclear Magnetic Resonance (NMR) spectrometry, mass loss, and elemental composition (carbon, hydrogen, and oxygen) of the char. Structural changes were examined by changes in porosity as measured by nitrogen gas adsorption. 13C NMR spectrometry, mass loss, and elemental composition were combined to estimate the mass of aromatic and aliphatic carbon remaining in the char. Mass loss and elemental composition were combined to estimate the chemical composition of material lost for various time intervals of heating. These analyses showed that aliphatic components in the test materials were either lost or converted to aromatic carbon early in the charring process. Nitrogen adsorption showed that no porosity develops for any of the test materials with heating at 250?C, even though substantial loss of material and changes in composition occurred. Porosity development coincided with the loss of aromatic carbon, indicating that micropores were developing within a fused-ring matrix.

Concentrations of trace elements and compounds in the airborne suspended particulate matter in Cleveland, Ohio, from August 1971 to August 1972 and their dependence on wind direction: Complete data listing and concentration roses

NASA Technical Reports Server (NTRS)

King, R. B.; Neustadter, H. E.

1976-01-01

Concentrations of 75 chemical constituents in the airborne particulate matter were measured in Cleveland, Ohio during 1971 and 1972. Daily values, maxima, geometric means and their standard deviations covering a 1-year period (45 to 50 sampling days) at each of 16 sites are presented on microfiche for 60 elements, and for a lesser number of days for 10 polycyclic aromatic hydrocarbon compounds (PAH), the aliphatic hydrocarbon compounds (AH) as a group and carbon. In addition, concentration roses showing directional properties are presented for 39 elements, 10 PAH and the AH as a group. The elements (except carbon) are shown both in terms of concentration and percentage of the suspended particulate matter.

Utilizing rare earth elements as tracers in high TDS reservoir brines in CCS applications

DOE PAGES

McLing, Travis; Smith, William; Smith, Robert

2014-12-31

In this paper we report the result of research associated with the testing of a procedures necessary for utilizing natural occurring trace elements, specifically the Rare Earth Elements (REE) as geochemical tracers in Carbon Capture and Storage (CCS) applications. Trace elements, particularly REE may be well suited to serve as in situ tracers for monitoring geochemical conditions and the migration of CO₂-charged waters within CCS storage systems. We have been conducting studies to determine the efficacy of using REE as a tracer and characterization tool in the laboratory, at a CCS analogue site in Soda Springs, Idaho, and at amore » proposed CCS reservoir at the Rock Springs Uplift, Wyoming. Results from field and laboratory studies have been encouraging and show that REE may be an effective tracer in CCS systems and overlying aquifers. In recent years, a series of studies using REE as a natural groundwater tracer have been conducted successfully at various locations around the globe. Additionally, REE and other trace elements have been successfully used as in situ tracers to describe the evolution of deep sedimentary Basins. Our goal has been to establish naturally occurring REE as a useful monitoring measuring and verification (MMV) tool in CCS research because formation brine chemistry will be particularly sensitive to changes in local equilibrium caused by the addition of large volumes of CO₂. Because brine within CCS target formations will have been in chemical equilibrium with the host rocks for millions of years, the addition of large volumes of CO₂ will cause reactions in the formation that will drive changes to the brine chemistry due to the pH change caused by the formation of carbonic acid. This CO₂ driven change in formation fluid chemistry will have a major impact on water rock reaction equilibrium in the formation, which will impart a change in the REE fingerprint of the brine that can measured and be used to monitor in situ reservoir conditions. Our research has shown that the REE signature imparted to the formation fluid by the introduction of CO₂ to the formation, can be measured and tracked as part of an MMV program. Additionally, this REE fingerprint may serve as an ideal tracer for fluid migration, both within the CCS target formation, and should formation fluids migrate into overlying aquifers. However application of REE and other trace elements to CCS system is complicated by the high salt content of the brines contained within the target formations. In the United States by regulation, in order for a geologic reservoir to be considered suitable for carbon storage, it must contain formation brine with total dissolved solids (TDS) > 10,000 ppm, and in most cases formation brines have TDS well in excess of that threshold. The high salinity of these brines creates analytical problems for elemental analysis, including element interference with trace metals in Inductively Coupled Plasma Mass Spectroscopy (ICP-MS) (i.e. element mass overlap due to oxide or plasma phenomenon). Additionally, instruments like the ICP-MS that are sensitive enough to measure trace elements down to the parts per trillion level are quickly oversaturated when water TDS exceeds much more than 1,000 ppm. Normally this problem is dealt with through dilution of the sample, bringing the water chemistry into the instruments working range. However, dilution is not an option when analyzing these formation brines for trace metals, because trace elements, specifically the REE, which occur in aqueous solutions at the parts per trillion levels. Any dilution of the sample would make REE detection impossible. Therefore, the ability to use trace metals as in situ natural tracers in high TDS brines environments requires the development of methods for pre-concentrating trace elements, while reducing the salinity and associated elemental interference such that the brines can be routinely analyzed by standard ICP-MS methods. As part of the Big Sky Carbon Sequestration Project the INL-CAES has developed a rapid, easy to use process that pre-concentrates trace metals, including REE, up to 100x while eliminating interfering ions (e.g. Ba, Cl). The process is straightforward, inexpensive, and requires little infrastructure, using only a single chromatography column with inexpensive, reusable, commercially available resins and wash chemicals. The procedure has been tested with synthetic brines (215,000 ppm or less TDS) and field water samples (up to 5,000 ppm TDS). Testing has produced data of high quality with REE capture efficiency exceeding 95%, while reducing interfering elements by > 99%.« less

Lab Analyses of Fenceline PM10 Air Filters

EPA Pesticide Factsheets

These spreadsheets show the analytical data on PM10 concentration, organic carbon, elemental carbon, and several trace metals at KCBX petroleum coke (also known as pet coke or petcoke) storage terminals in Chicago, Illinois.

Marine Bioinorganic Chemistry: The Role of Trace Metals in the Oceanic Cycles of Major Nutrients

NASA Astrophysics Data System (ADS)

Morel, F. M. M.; Milligan, A. J.; Saito, M. A.

2003-12-01

The bulk of living biomass is chiefly made up of only a dozen "major" elements - carbon, hydrogen, oxygen, nitrogen, phosphorus, sodium, potassium, chlorine, calcium, magnesium, sulfur (and silicon in diatoms) - whose proportions vary within a relatively narrow range in most organisms. A number of trace elements, particularly first row transition metals - manganese, iron, nickel, cobalt, copper, and zinc - are also "essential" for the growth of organisms. At the molecular level, the chemical mechanisms by which such elements function as active centers or structural factors in enzymes and by which they are accumulated and stored by organisms is the central topic of bioinorganic chemistry. At the scale of ocean basins, the interplay of physical, chemical, and biological processes that govern the cycling of biologically essential elements in seawater is the subject of marine biogeochemistry. For those interested in the growth of marine organisms, particularly in the one-half of the Earth's primary production contributed by marine phytoplankton, bioinorganic chemistry and marine biogeochemistry are critically linked by the extraordinary paucity of essential trace elements in surface seawater, which results from their biological utilization and incorporation in sinking organic matter. How marine organisms acquire elements that are present at nano- or picomolar concentrations in surface seawater; how they perform critical enzymatic functions when necessary metal cofactors are almost unavailable are the central topics of "marine bioinorganic chemistry." The central aim of this field is to elucidate at the molecular level the metal-dependent biological processes involved in the major biogeochemical cycles.By examining the solutions that emerged from the problems posed by the scarcity of essential trace elements, marine bioinorganic chemists bring to light hitherto unknown ways to take up or utilize trace elements, new molecules, and newer "essential" elements. Focusing on molecular mechanisms involved in such processes as inorganic carbon fixation, organic carbon respiration, or nitrogen transformation, they explain how the cycles of trace elements are critically linked to those of major nutrients such as carbon or nitrogen. But we have relatively little understanding of the binding molecules and the enzymes that mediate the biochemical role of trace metals in the marine environment. In this sense, this chapter is more a "preview" than a review of the field of marine bioinorganic chemistry. To exemplify the concepts and methods of this field, we have chosen to focus on one of its most important topics: the potentially limiting role of trace elements in primary marine production. As a result we center our discussion on particular subsets of organisms, biogeochemical cycles, and trace elements. Our chief actors are marine phytoplankton, particularly eukaryotes, while heterotrophic bacteria make only cameo appearances. The biogeochemical cycles that will serve as our plot are those of the elements involved in phytoplankton growth, the major algal nutrients - carbon, nitrogen, phosphorus, and silicon - leaving aside, e.g., the interesting topic of the marine sulfur cycle. Seven trace metals provide the intrigue: manganese, iron, nickel, cobalt, copper, zinc, and cadmium. But several other trace elements such as selenium, vanadium, molybdenum, and tungsten (and, probably, others not yet identified) will assuredly add further twists in future episodes.We begin this chapter by discussing what we know of the concentrations of trace elements in marine microorganisms and of the relevant mechanisms and kinetics of trace-metal uptake. We then review the biochemical role of trace elements in the marine cycles of carbon, nitrogen, phosphorus, and silicon. Using this information, we examine the evidence, emanating from both laboratory cultures and field measurements, relevant to the mechanisms and the extent of control by trace metals of marine biogeochemical cycles. Before concluding with a wistful glimpse of the future of marine bioinorganic chemistry we discuss briefly some paleoceanographic aspects of this new field: how the chemistry of the planet "Earth" - particularly the concentrations of trace elements in the oceans - has evolved since its origin, chiefly as a result of biological processes and how the evolution of life has, in turn, been affected by the availability of essential trace elements.

Status of the Monte Carlo library least-squares (MCLLS) approach for non-linear radiation analyzer problems

NASA Astrophysics Data System (ADS)

Gardner, Robin P.; Xu, Libai

2009-10-01

The Center for Engineering Applications of Radioisotopes (CEAR) has been working for over a decade on the Monte Carlo library least-squares (MCLLS) approach for treating non-linear radiation analyzer problems including: (1) prompt gamma-ray neutron activation analysis (PGNAA) for bulk analysis, (2) energy-dispersive X-ray fluorescence (EDXRF) analyzers, and (3) carbon/oxygen tool analysis in oil well logging. This approach essentially consists of using Monte Carlo simulation to generate the libraries of all the elements to be analyzed plus any other required background libraries. These libraries are then used in the linear library least-squares (LLS) approach with unknown sample spectra to analyze for all elements in the sample. Iterations of this are used until the LLS values agree with the composition used to generate the libraries. The current status of the methods (and topics) necessary to implement the MCLLS approach is reported. This includes: (1) the Monte Carlo codes such as CEARXRF, CEARCPG, and CEARCO for forward generation of the necessary elemental library spectra for the LLS calculation for X-ray fluorescence, neutron capture prompt gamma-ray analyzers, and carbon/oxygen tools; (2) the correction of spectral pulse pile-up (PPU) distortion by Monte Carlo simulation with the code CEARIPPU; (3) generation of detector response functions (DRF) for detectors with linear and non-linear responses for Monte Carlo simulation of pulse-height spectra; and (4) the use of the differential operator (DO) technique to make the necessary iterations for non-linear responses practical. In addition to commonly analyzed single spectra, coincidence spectra or even two-dimensional (2-D) coincidence spectra can also be used in the MCLLS approach and may provide more accurate results.

Modeling rates of DOC degradation using DOM composition and hydroclimatic variables

NASA Astrophysics Data System (ADS)

Moody, C. S.; Worrall, F.

2017-05-01

The fluvial fluxes of dissolved organic carbon (DOC) from peatlands form an important part of that ecosystem's carbon cycle, contributing approximately 35% of the overall peatland carbon budget. The in-stream processes acting on the DOC, such as photodegradation and biodegradation, can lead to DOC loss and thus contribute CO2 to the atmosphere. The aim of this study was to understand what controls the rates of DOC degradation. Water samples from a headwater, peat-covered catchment, were collected over a 23 month period and analyzed for the DOC degradation rate and dissolved organic matter (DOM) composition in the context of hydroclimatic monitoring. Measures of DOM composition included 13C solid-state nuclear magnetic resonance spectroscopy, bomb calorimetry, and elemental analysis. Regression analysis showed that there was a significant role for the composition of the DOM in controlling degradation with degradation rates significantly increasing with the proportion of aldehyde and carboxylic acid functional groups but decreasing with the proportion of N-alkyl functional groups. The highest rates of DOC degradation occurred when aldehyde functionality was at its greatest and this occurred on the recession limb of storm hydrographs. Including this knowledge into models of fluvial carbon fate for an 818 km2 catchment gave an annual average DOC removal rate of 67% and 50% for total organic carbon, slightly lower than previously predicted. The compositional controls suggest that DOM is primarily being used as a ready energy source to the aquatic ecosystem rather than as a nutrient source.

The Preservation of Organic Matter and its Signatures at Experimental Lava Flow Interfaces: Implications for Mars

NASA Astrophysics Data System (ADS)

Junium, C. K.; Karson, J. A.; Kahan, T.

2015-12-01

The oxidizing nature of Martian soils suggests that the preservation of organic molecules or any direct evidence for life at the surface may not be possible. Future rover missions will need to focus on a variety localitions including those that provide the best possibility for the preservation of organic matter. Volcanic glass and basalt flow surfaces are favored environments for microbial colonization on Earth and this may have been similar on an early Mars. Trace metals and nutrients from easily weathered surface would have provided nutrients as well as substrates for chemolithoautotrophs. In regions of igneous activity, successive flows could overrun microbial communities, trapping potential organic signatures between flows. Here we present experimental evidence for the preservation of organic matter between lava flows and that flow interfaces may be excellent sites for exploratory efforts in the search for Martian biosignatures. We performed a series of experiments using the infrastructure of the Syracuse Lava Project that allows for natural-scale lava flows of up to several hundred kilograms. We subjected cyanobacterial organic matter to overrun by lava under a variety of conditions. In all cases organic matter was preserved between lava flows as chars on the overrun 'colonized" lava and as thin shiny carbon coatings on the overriding flow. The carbon coatings are likely the result of rapid heating and pyrolysis of organic matter that sears to the underside of the overriding lava. Controls yielded no positive signatures for organic matter. We also tested the degree to which the organic matter could be detected remotely using technologies that are found on the Mars Science Laboratory or planned for future missions. We employed elemental and stable isotopes analysis, and Raman spectroscopy. Elemental analysis demonstrated that organic carbon and nitrogen remain in the charred material and that the carbon and nitrogen isotopes of the chars do not deviate significantly from the precursor organic matter (-24.3‰ cyanobacterial biomass; -24.2‰ black carbon). Raman spectroscopy revealed spectra for black carbon, even from the thinnest carbon coatings on overriding lava surfaces. These findings demonstrate that if organic matter is preserved beneath lava flows it may be readily detectable.

Semi-continuous mass closure of the major components of fine particulate matter in Riverside, CA

NASA Astrophysics Data System (ADS)

Grover, Brett D.; Eatough, Norman L.; Woolwine, Woods R.; Cannon, Justin P.; Eatough, Delbert J.; Long, Russell W.

The application of newly developed semi-continuous aerosol monitors allows for the measurement of all the major species of PM 2.5 on a 1-h time basis. Temporal resolution of both non-volatile and semi-volatile species is possible. A suite of instruments to measure the major chemical species of PM 2.5 allows for semi-continuous mass closure. A newly developed dual-oven Sunset carbon monitor is used to measure non-volatile organic carbon, semi-volatile organic carbon and elemental carbon. Inorganic species, including sulfate and nitrate, can be measured with an ion chromatograph based sampler. Comparison of the sum of the major chemical species in an urban aerosol with mass measured by an FDMS resulted in excellent agreement. Linear regression analysis resulted in a zero-intercept slope of 0.98±0.01 with an R2=0.86. One-hour temporal resolution of the major species of PM 2.5 may reduce the uncertainty in receptor based source apportionment modeling, will allow for better forecasting of PM 2.5 episodes, and may lead to increased understanding of related health effects.

Quantitative ion beam analysis of M-C-O systems: application to an oxidized uranium carbide sample

NASA Astrophysics Data System (ADS)

Martin, G.; Raveu, G.; Garcia, P.; Carlot, G.; Khodja, H.; Vickridge, I.; Barthe, M. F.; Sauvage, T.

2014-04-01

A large variety of materials contain both carbon and oxygen atoms, in particular oxidized carbides, carbon alloys (as ZrC, UC, steels, etc.), and oxycarbide compounds (SiCO glasses, TiCO, etc.). Here a new ion beam analysis methodology is described which enables quantification of elemental composition and oxygen concentration profile over a few microns. It is based on two procedures. The first, relative to the experimental configuration relies on a specific detection setup which is original in that it enables the separation of the carbon and oxygen NRA signals. The second concerns the data analysis procedure i.e. the method for deriving the elemental composition from the particle energy spectrum. It is a generic algorithm and is here successfully applied to characterize an oxidized uranium carbide sample, developed as a potential fuel for generation IV nuclear reactors. Furthermore, a micro-beam was used to simultaneously determine the local elemental composition and oxygen concentration profiles over the first microns below the sample surface. This method is adapted to the determination of the composition of M?C?O? compounds with a sensitivity on elemental atomic concentrations around 1000 ppm.

Tension-Compression Fatigue of an Oxide/Oxide Ceramic Matrix Composite at Elevated Temperature in Air and Steam Environments

DTIC Science & Technology

2015-03-26

method has been successfully used with several materials such as silicon carbide fiber - silicon carbide matrix ( SiC / SiC ) CMCs with carbon and boron...elements [14]. These advanced ceramics include oxides, nitrides and carbides of silicon , aluminum, titanium, and zirconium [12]. One of the most...oxides over silicon carbide and other non-oxide materials. In fact, it is the inherent stability of oxides in oxidizing environments which originally

Carbon-rich particles in Comet Halley

NASA Technical Reports Server (NTRS)

Clark, Benton C.

1990-01-01

The majority of particles detected in the coma of Comet Halley contain carbon atoms; many of these grains appear to consist preponderately or only of light elements. These light-element particles may be composed of organic compounds. Of the possible combinations of the elements hydrogen, carbon, nitrogen, and oxygen, numerous examples are found of particles containing the combinations (H,C,O,N), (H,C,N), (H,C,O), and (H,C). These results may bear on the recent detection of polyoxymethylene fragments, the observation of cyanojets (CN patterns consistent with release from solid particles), the possible presence of cyanopolyacetylenes or HCN polymer and the make-up of the CHON particles. If cometary matter could reach the surface of the earth without complete disruption, these diverse organic and mixed particles could create unique microenvironments, possibly with significant or even pivotal prebiotic chemical activity. Here a speculative insight into possible relationships between carbon in comets and carbon in life is given, as well as a brief overview of on-going analysis of data from the highly successful Particle Impact Analyzer (PIA) experiment flown on the Giotto spacecraft for the flyby of Comet Halley (development and implementation of PIA was under the direction of J. Kissel of the Max Planck Institute for Kernphysik, Heidelberg). PIA is a time-of-flight analyzer which obtains mass spectra of ions from individual particles impacting on a Pt-Ag foil target within the instrument.

The role of African dust in the formation of Quaternary soils on Mallorca, Spain and implications for the genesis of Red Mediterranean soils

USGS Publications Warehouse

Muhs, D.R.; Budahn, J.; Avila, A.; Skipp, G.; Freeman, J.; Patterson, D.

2010-01-01

African dust additions explain the origin of terra rossa soils that are common on the carbonate-platform island of Mallorca, Spain. Mineralogical and geochemical analyses indicate that Quaternary carbonate eolianites on Mallorca have a very high purity, usually composed of more than 90% carbonate minerals (calcite, dolomite, and aragonite). In contrast, terra rossa soils developed on these eolianites have lower carbonate contents and contain higher concentrations of quartz and other silicates. Analyses of immobile trace elements indicate that the non-carbonate fractions of the eolianites have distinctive Zr/Hf, La/Yb, Cr/Sc and Th/Ta values that differ from the superjacent terra rossa soils. These observations indicate that even if sufficient dissolution of the eolianite had taken place to create the soils by residual accumulation, immobile element ratios in the soils require an external source. However, Zr/Hf, La/Yb, Cr/Sc and Th/Ta values in the soils fall within the range of values for these element ratios in African dust collected on Barbados and mainland Spain. We conclude that the silicate fractions of terra rossa soils on Mallorca are derived mainly, though not wholly, from far-traveled African dust, and this process may explain the origin of other terra rossa soils found in southern Europe. ?? 2010.

The nu-process

NASA Technical Reports Server (NTRS)

Woosley, S. E.; Hartmann, D. H.; Hoffman, R. D.; Haxton, W. C.

1990-01-01

As the core of a massive star collapses to form a neutron star, the flux of neutrinos in the overlying shells of heavy elements becomes so great that, despite the small cross section, substantial nuclear transmutation is induced. Neutrinos excite heavy elements and even helium to particle unbound levels. The evaporation of a single neutron or proton, and the back reaction of these nucleons on other species present, significantly alters the outcome of traditional nucleosynthesis calculations leading to a new process: nu-nucleosynthesis. Modifications to traditional hydrostatic and explosive varieties of helium, carbon, neon, oxygen, and silicon burning are considered. The results show that a large number of rare isotopes, including many of the odd-Z nuclei from boron through copper, owe much of their present abundance in nature to this process.

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

Gschneidner, Jr., Karl A.; Schmidt, Frederick A.

A carbothermic reduction method is provided for reducing a La-, Ce-, MM-, and/or Y-containing oxide in the presence of carbon and a source of a reactant element comprising Si, Ge, Sn, Pb, As, Sb, Bi, and/or P to form an intermediate alloy material including a majority of La, Ce, MM, and/or Y and a minor amount of the reactant element. The intermediate material is useful as a master alloy for in making negative electrode materials for a metal hydride battery, as hydrogen storage alloys, as master alloy additive for addition to a melt of commercial Mg and Al alloys, steels,more » cast irons, and superalloys; or in reducing Sm.sub.2O.sub.3 to Sm metal for use in Sm--Co permanent magnets.« less

Comparing the detection of iron-based pottery pigment on a carbon-coated sherd by SEM-EDS and by Micro-XRF-SEM.

PubMed

Pendleton, Michael W; Washburn, Dorothy K; Ellis, E Ann; Pendleton, Bonnie B

2014-03-01

The same sherd was analyzed using a scanning electron microscope with energy dispersive spectroscopy (SEM-EDS) and a micro X-ray fluorescence tube attached to a scanning electron microscope (Micro-XRF-SEM) to compare the effectiveness of elemental detection of iron-based pigment. To enhance SEM-EDS mapping, the sherd was carbon coated. The carbon coating was not required to produce Micro-XRF-SEM maps but was applied to maintain an unbiased comparison between the systems. The Micro-XRF-SEM analysis was capable of lower limits of detection than that of the SEM-EDS system, and therefore the Micro-XRF-SEM system could produce elemental maps of elements not easily detected by SEM-EDS mapping systems. Because SEM-EDS and Micro-XRF-SEM have been used for imaging and chemical analysis of biological samples, this comparison of the detection systems should be useful to biologists, especially those involved in bone or tooth (hard tissue) analysis.

Comparing the Detection of Iron-Based Pottery Pigment on a Carbon-Coated Sherd by SEM-EDS and by Micro-XRF-SEM

PubMed Central

Pendleton, Michael W.; Washburn, Dorothy K.; Ellis, E. Ann; Pendleton, Bonnie B.

2014-01-01

The same sherd was analyzed using a scanning electron microscope with energy dispersive spectroscopy (SEM-EDS) and a micro X-ray fluorescence tube attached to a scanning electron microscope (Micro-XRF-SEM) to compare the effectiveness of elemental detection of iron-based pigment. To enhance SEM-EDS mapping, the sherd was carbon coated. The carbon coating was not required to produce Micro-XRF-SEM maps but was applied to maintain an unbiased comparison between the systems. The Micro-XRF-SEM analysis was capable of lower limits of detection than that of the SEM-EDS system, and therefore the Micro-XRF-SEM system could produce elemental maps of elements not easily detected by SEM-EDS mapping systems. Because SEM-EDS and Micro-XRF-SEM have been used for imaging and chemical analysis of biological samples, this comparison of the detection systems should be useful to biologists, especially those involved in bone or tooth (hard tissue) analysis. PMID:24600333

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.

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

Facile synthesis and application of a carbon foam with large mesopores.

PubMed

Fu, Liling; Qi, Genggeng; Sahore, Ritu; Sougrat, Rachid; DiSalvo, Francis J; Giannelis, Emmanuel P

2013-11-28

By combining elements of hard- and soft-templating, a facile synthesis method for carbon foams with large mesopores has been demonstrated. A commercial Pluronic surfactant was used as the structure-directing agent as well as the carbon precursor. No micelle swelling agent or post treatment is necessary to enlarge mesopores. As such this method requires fewer synthesis steps and is highly scalable. The as-synthesized meso-carbons showed potential applications in the fields of carbon oxide capture and lithium-sulfur batteries.

URBAN SCALE VARIABILITY OF PM 2.5 COMPONENTS

EPA Science Inventory

This study is being conducted in a large city in the mid-west U.S. The preliminary spatial analyses for particulate nitrate, selected trace elements, and organic and elemental carbon (OC/EC) will be presented.

Nonaqueous method for dissolving lanthanide and actinide metals

DOEpatents

Crisler, L.R.

1975-11-11

Lanthanide and actinide beta-diketonate complex molecular compounds are produced by reacting a beta-diketone compound with a lanthanide or actinide element in the elemental metallic state in a mixture of carbon tetrachloride and methanol.

Biological and land use controls on the isotopic composition of aquatic carbon in the Upper Mississippi River Basin

NASA Astrophysics Data System (ADS)

Voss, Britta M.; Wickland, Kimberly P.; Aiken, George R.; Striegl, Robert G.

2017-08-01

Riverine ecosystems receive organic matter (OM) from terrestrial sources, internally produce new OM, and biogeochemically cycle and modify organic and inorganic carbon. Major gaps remain in the understanding of the relationships between carbon sources and processing in river systems. Here we synthesize isotopic, elemental, and molecular properties of dissolved organic carbon (DOC), particulate organic carbon (POC), and dissolved inorganic carbon (DIC) in the Upper Mississippi River (UMR) system above Wabasha, MN, including the main stem Mississippi River and its four major tributaries (Minnesota, upper Mississippi, St. Croix, and Chippewa Rivers). Our goal was to elucidate how biological processing modifies the chemical and isotopic composition of aquatic carbon pools during transport downstream in a large river system with natural and man-made impoundments. Relationships between land cover and DOC carbon-isotope composition, absorbance, and hydrophobic acid content indicate that DOC retains terrestrial carbon source information, while the terrestrial POC signal is largely replaced by autochthonous organic matter, and DIC integrates the influence of in-stream photosynthesis and respiration of organic matter. The UMR is slightly heterotrophic throughout the year, but pools formed by low-head navigation dams and natural impoundments promote a shift toward autotrophic conditions, altering aquatic ecosystem dynamics and POC and DIC compositions. Such changes likely occur in all major river systems affected by low-head dams and need to be incorporated into our understanding of inland water carbon dynamics and processes controlling CO2 emissions from rivers, as new navigation and flood control systems are planned for future river and water resources management.

Biological and land use controls on the isotopic composition of aquatic carbon in the Upper Mississippi River Basin

USGS Publications Warehouse

Voss, Britta; Wickland, Kimberly P.; Aiken, George R.; Striegl, Robert G.

2017-01-01

Riverine ecosystems receive organic matter (OM) from terrestrial sources, internally produce new OM, and biogeochemically cycle and modify organic and inorganic carbon. Major gaps remain in the understanding of the relationships between carbon sources and processing in river systems. Here we synthesize isotopic, elemental, and molecular properties of dissolved organic carbon (DOC), particulate organic carbon (POC), and dissolved inorganic carbon (DIC) in the Upper Mississippi River (UMR) system above Wabasha, MN, including the main stem Mississippi River and its four major tributaries (Minnesota, upper Mississippi, St. Croix, and Chippewa Rivers). Our goal was to elucidate how biological processing modifies the chemical and isotopic composition of aquatic carbon pools during transport downstream in a large river system with natural and man-made impoundments. Relationships between land cover and DOC carbon-isotope composition, absorbance, and hydrophobic acid content indicate that DOC retains terrestrial carbon source information, while the terrestrial POC signal is largely replaced by autochthonous organic matter, and DIC integrates the influence of in-stream photosynthesis and respiration of organic matter. The UMR is slightly heterotrophic throughout the year, but pools formed by low-head navigation dams and natural impoundments promote a shift towards autotrophic conditions, altering aquatic ecosystem dynamics and POC and DIC composition. Such changes likely occur in all major river systems affected by low-head dams and need to be incorporated into our understanding of inland water carbon dynamics and processes controlling CO2 emissions from rivers, as new navigation and flood control systems are planned for future river and water resources management.

Carbon and nitrogen abundances determined from transition layer lines

NASA Technical Reports Server (NTRS)

Boehm-Vitense, Erika; Mena-Werth, Jose

1992-01-01

The possibility of determining relative carbon, nitrogen, and silicon abundances from the emission-line fluxes in the lower transition layers between stellar chromospheres and coronae is explored. Observations for main-sequence and luminosity class IV stars with presumably solar element abundances show that for the lower transition layers Em = BT sup -gamma. For a given carbon abundance the constants gamma and B in this relation can be determined from the C II and C IV emission-line fluxes. From the N V and S IV lines, the abundances of these elements relative to carbon can be determined from their surface emission-line fluxes. Ratios of N/C abundances determined in this way for some giants and supergiants agree within the limits of errors with those determined from molecular bands. For giants, an increase in the ratio of N/C at B-V of about 0.8 is found, as expected theoretically.

Fabrication of 3D Carbon Microelectromechanical Systems (C-MEMS).

PubMed

Pramanick, Bidhan; Martinez-Chapa, Sergio O; Madou, Marc; Hwang, Hyundoo

2017-06-17

A wide range of carbon sources are available in nature, with a variety of micro-/nanostructure configurations. Here, a novel technique to fabricate long and hollow glassy carbon microfibers derived from human hairs is introduced. The long and hollow carbon structures were made by the pyrolysis of human hair at 900 °C in a N2 atmosphere. The morphology and chemical composition of natural and pyrolyzed human hairs were investigated using scanning electron microscopy (SEM) and electron-dispersive X-ray spectroscopy (EDX), respectively, to estimate the physical and chemical changes due to pyrolysis. Raman spectroscopy was used to confirm the glassy nature of the carbon microstructures. Pyrolyzed hair carbon was introduced to modify screen-printed carbon electrodes ; the modified electrodes were then applied to the electrochemical sensing of dopamine and ascorbic acid. Sensing performance of the modified sensors was improved as compared to the unmodified sensors. To obtain the desired carbon structure design, carbon micro-/nanoelectromechanical system (C-MEMS/C-NEMS) technology was developed. The most common C-MEMS/C-NEMS fabrication process consists of two steps: (i) the patterning of a carbon-rich base material, such as a photosensitive polymer, using photolithography; and (ii) carbonization through the pyrolysis of the patterned polymer in an oxygen-free environment. The C-MEMS/NEMS process has been widely used to develop microelectronic devices for various applications, including in micro-batteries, supercapacitors, glucose sensors, gas sensors, fuel cells, and triboelectric nanogenerators. Here, recent developments of a high-aspect ratio solid and hollow carbon microstructures with SU8 photoresists are discussed. The structural shrinkage during pyrolysis was investigated using confocal microscopy and SEM. Raman spectroscopy was used to confirm the crystallinity of the structure, and the atomic percentage of the elements present in the material before and after pyrolysis was measured using EDX.

Measuring the decomposition of organic carbon sequestered by salt marsh sediment

NASA Astrophysics Data System (ADS)

Light, T.; Mctigue, N.; Currin, C.

2016-12-01

As atmospheric carbon dioxide concentrations continue to rise, salt marshes are increasingly being recognized as a natural carbon sink, for large amounts of organic carbon are sequestered by salt marsh sediments. However, little is known regarding the fate of this "blue carbon" after salt marsh sediment is disturbed via erosion or lost due to sea level rise. This investigation explored novel methodologies for determining the lability of carbon sequestered by salt marsh sediment. Sediment cores were collected from a Spartina alterniflora-dominated marsh in Camp Lejeune, NC, and elemental analysis revealed that the upper 76 cm of sediment at the site contains a total carbon stock of 28.4 kg /m2. Sediment ranging from 251-545 years old, as determined through radiocarbon dating, was incubated under sub-aerial and aqueous conditions for 18 days and 25 days respectively. Carbon dioxide flux measurements revealed that shallower sediment organic matter decomposed more rapidly than deeper sediment in sub-aerial incubations, but decomposition was fairly slow in both treatments. No significant organic matter decomposition was observed in the aqueous incubations, as revealed by analyses of organic carbon remaining after the incubation period. The aqueous incubation included a treatment that had been "primed" with highly labile yeast extract, but no significant priming effect was observed over 25 days. While further investigation on the fate of this sediment carbon is needed, these preliminary findings indicate that salt marshes facilitate long-term carbon sequestration even after disturbances. This in turn supports the argument for mitigating anthropogenic carbon dioxide emissions through salt marsh restoration, and supports a policy of preserving and conserving coastal wetlands for this valuable ecosystem service.

77 FR 66929 - Approval and Promulgation of Implementation Plans; State of Idaho; Regional Haze State...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-11-08

.... Simplot, a phosphate fertilizer manufacturing facility which is 86 km from Craters of the Moon National... any type is primarily due to emissions of organic carbon and elemental carbon, and to a lesser extent... organic carbon emissions in 2018 from natural fires compared to 4,100 tons from anthropogenic fires. With...

Tracing the source of soil organic matter eroded from temperate forest catchments using carbon and nitrogen isotopes

Treesearch

Emma P. McCorkle; Asmeret Asefaw Berhe; Carolyn T. Hunsaker; Dale W. Johnson; Karis J. McFarlane; Marilyn L. Fogel; Stephen C. Hart

2016-01-01

Soil erosion continuously redistributes soil and associated soil organic matter (SOM) on the Earth's surface, with important implications for biogeochemical cycling of essential elements and terrestrial carbon sequestration. Despite the importance of soil erosion, surprisingly few studies have evaluated the sources of eroded carbon (C). We used natural abundance...

Lead carbonate scintillator materials

DOEpatents

Derenzo, Stephen E.; Moses, William W.

1991-01-01

Improved radiation detectors containing lead carbonate or basic lead carbonate as the scintillator element are disclosed. Both of these scintillators have been found to provide a balance of good stopping power, high light yield and short decay constant that is superior to other known scintillator materials. The radiation detectors disclosed are favorably suited for use in general purpose detection and in medical uses.

Carbon cycle observations: gaps threaten climate mitigation policies

Treesearch

Richard Birdsey; Nick Bates; MIke Behrenfeld; Kenneth Davis; Scott C. Doney; Richard Feely; Dennis Hansell; Linda Heath; et al.

2009-01-01

Successful management of carbon dioxide (CO2) requires robust and sustained carbon cycle observations. Yet key elements of a national observation network are lacking or at risk. A U.S. National Research Council review of the U.S. Climate Change Science Program earlier this year highlighted the critical need for a U.S. climate observing system to...

Doped carbon-sulfur species nanocomposite cathode for Li--S batteries

DOEpatents

Wang, Donghai; Xu, Tianren; Song, Jiangxuan

2015-12-29

We report a heteroatom-doped carbon framework that acts both as conductive network and polysulfide immobilizer for lithium-sulfur cathodes. The doped carbon forms chemical bonding with elemental sulfur and/or sulfur compound. This can significantly inhibit the diffusion of lithium polysulfides in the electrolyte, leading to high capacity retention and high coulombic efficiency.

Chemical Analysis of a Carbon-enhanced Very Metal-poor Star: CD-27 14351

NASA Astrophysics Data System (ADS)

Karinkuzhi, Drisya; Goswami, Aruna; Masseron, Thomas

2017-01-01

We present, for the first time, an abundance analysis of a very metal-poor carbon-enhanced star CD-27 14351 based on a high-resolution (R ˜ 48,000) FEROS spectrum. Our abundance analysis performed using local thermodynamic equilibrium model atmospheres shows that the object is a cool star with stellar atmospheric parameters, effective temperature Teff = 4335 K, surface gravity log g = 0.5, microturbulence ξ = 2.42 km s-1, and metallicity [Fe/H] = -2.6. The star exhibits high carbon and nitrogen abundances with [C/Fe] = 2.89 and [N/Fe] = 1.89. Overabundances of neutron-capture elements are evident in Ba, La, Ce, and Nd, with estimated [X/Fe] > 1, the largest enhancement being seen in Ce with [Ce/Fe] = 2.63. While the first peak s-process elements Sr and Y are found to be enhanced with respect to Fe, ([Sr/Fe] = 1.73 and [Y/Fe] = 1.91), the third peak s-process element Pb could not be detected in our spectrum at the given resolution. Europium, primarily an r-process element also shows an enhancement with [Eu/Fe] = 1.65. With [Ba/Eu] = 0.12, the object CD-27 14351 satisfies the classification criterion for a CEMP-r/s star. The elemental abundance distributions observed in this star are discussed in light of the chemical abundances observed in other CEMP stars in the literature.

Normal and Outlying Populations of the Milky Way Stellar Halo at [Fe/H] <-2

NASA Astrophysics Data System (ADS)

Cohen, Judith G.; Christlieb, Norbert; Thompson, Ian; McWilliam, Andrew; Shectman, Stephen; Reimers, Dieter; Wisotzki, Lutz; Kirby, Evan

2013-11-01

From detailed abundance analysis of >100 Hamburg/ESO candidate extremely metal-poor (EMP) stars we find 45 with [Fe/H] < -3.0 dex. We identify a heretofore unidentified group: Ca-deficient stars with sub-solar [Ca/Fe] ratios and the lowest neutron-capture abundances; the Ca-deficient group comprises ~10% of the sample, excluding Carbon stars. Our radial velocity distribution shows that the carbon-enhanced stars with no s-process enhancements, CEMP-no, and which do not show C2 bands are not preferentially binary systems. Ignoring Carbon stars, approximately 15% of our sample are strong (>=5σ) outliers in one or more elements between Mg and Ni; this rises to ~19% if very strong (>=10σ) outliers for Sr and Ba are included. Examples include: HE0305-0554 with the lowest [Ba/H] known; HE1012-1540 and HE2323-0256, two (non-velocity variable) C-rich stars with very strong [Mg,Al/Fe] enhancements; and HE1226-1149, an extremely r-process rich star. Based in part on observations obtained in part at the W. M. Keck Observatory, which is operated jointly by the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration.

Rating locomotive crew diesel emission exposure profiles using statistics and Bayesian Decision Analysis.

PubMed

Hewett, Paul; Bullock, William H

2014-01-01

For more than 20 years CSX Transportation (CSXT) has collected exposure measurements from locomotive engineers and conductors who are potentially exposed to diesel emissions. The database included measurements for elemental and total carbon, polycyclic aromatic hydrocarbons, aromatics, aldehydes, carbon monoxide, and nitrogen dioxide. This database was statistically analyzed and summarized, and the resulting statistics and exposure profiles were compared to relevant occupational exposure limits (OELs) using both parametric and non-parametric descriptive and compliance statistics. Exposure ratings, using the American Industrial Health Association (AIHA) exposure categorization scheme, were determined using both the compliance statistics and Bayesian Decision Analysis (BDA). The statistical analysis of the elemental carbon data (a marker for diesel particulate) strongly suggests that the majority of levels in the cabs of the lead locomotives (n = 156) were less than the California guideline of 0.020 mg/m(3). The sample 95th percentile was roughly half the guideline; resulting in an AIHA exposure rating of category 2/3 (determined using BDA). The elemental carbon (EC) levels in the trailing locomotives tended to be greater than those in the lead locomotive; however, locomotive crews rarely ride in the trailing locomotive. Lead locomotive EC levels were similar to those reported by other investigators studying locomotive crew exposures and to levels measured in urban areas. Lastly, both the EC sample mean and 95%UCL were less than the Environmental Protection Agency (EPA) reference concentration of 0.005 mg/m(3). With the exception of nitrogen dioxide, the overwhelming majority of the measurements for total carbon, polycyclic aromatic hydrocarbons, aromatics, aldehydes, and combustion gases in the cabs of CSXT locomotives were either non-detects or considerably less than the working OELs for the years represented in the database. When compared to the previous American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit value (TLV) of 3 ppm the nitrogen dioxide exposure profile merits an exposure rating of AIHA exposure category 1. However, using the newly adopted TLV of 0.2 ppm the exposure profile receives an exposure rating of category 4. Further evaluation is recommended to determine the current status of nitrogen dioxide exposures. [Supplementary materials are available for this article. Go to the publisher's online edition of Journal of Occupational and Environmental Hygiene for the following free supplemental resource: additional text on OELs, methods, results, and additional figures and tables.].

Trace elements and radon in groundwater across the United States, 1992-2003

USGS Publications Warehouse

Ayotte, Joseph D.; Gronberg, Jo Ann M.; Apodaca, Lori E.

2011-01-01

Trace-element concentrations in groundwater were evaluated for samples collected between 1992 and 2003 from aquifers across the United States as part of the U.S. Geological Survey National Water-Quality Assessment Program. This study describes the first comprehensive analysis of those data by assessing occurrence (concentrations above analytical reporting levels) and by comparing concentrations to human-health benchmarks (HHBs). Data from 5,183 monitoring and drinking-water wells representing more than 40 principal and other aquifers in humid and dry regions and in various land-use settings were used in the analysis. Trace elements measured include aluminum (Al), antimony (Sb), arsenic (As), barium (Ba), beryllium (Be), boron (B), cadmium (Cd), chromium (Cr), cobalt (Co), copper (Cu), iron (Fe), lead (Pb), lithium (Li), manganese (Mn), molybdenum (Mo), nickel (Ni), selenium (Se), silver (Ag), strontium (Sr), thallium (Tl), uranium (U), vanadium (V), and zinc (Zn). Radon (Rn) gas also was measured and is included in the data analysis. Climate influenced the occurrence and distribution of trace elements in groundwater whereby more trace elements occurred and were found at greater concentrations in wells in drier regions of the United States than in humid regions. In particular, the concentrations of As, Ba, B, Cr, Cu, Mo, Ni, Se, Sr, U, V, and Zn were greater in the drier regions, where processes such as chemical evolution, ion complexation, evaporative concentration, and redox (oxidation-reduction) controls act to varying degrees to mobilize these elements. Al, Co, Fe, Pb, and Mn concentrations in groundwater were greater in humid regions of the United States than in dry regions, partly in response to lower groundwater pH and (or) more frequent anoxic conditions. In groundwater from humid regions, concentrations of Cu, Pb, Rn, and Zn were significantly greater in drinking-water wells than in monitoring wells. Samples from drinking-water wells in dry regions had greater concentrations of As, Ba, Pb, Li, Sr, V, and Zn, than samples from monitoring wells. In humid regions, however, concentrations of most trace elements were greater in monitoring wells than in drinking-water wells; the exceptions were Cu, Pb, Zn, and Rn. Cu, Pb, and Zn are common trace elements in pumps and pipes used in the construction of drinking-water wells, and contamination from these sources may have contributed to their concentrations. Al, Sb, Ba, B, Cr, Co, Fe, Mn, Mo, Ni, Se, Sr, and U concentrations were all greater in monitoring wells than in drinking-water wells in humid regions. Groundwater from wells in agricultural settings had greater concentrations of As, Mo, and U than groundwater from wells in urban settings, possibly owing to greater pH in the agricultural wells. Significantly greater concentrations of B, Cr, Se, Ag, Sr, and V also were found in agricultural wells in dry regions. Groundwater from dry-region urban wells had greater concentrations of Co, Fe, Pb, Li, Mn, and specific conductance than groundwater from agricultural wells. The geologic composition of aquifers and aquifer geochemistry are among the major factors affecting trace-element occurrence. Trace-element concentrations in groundwater were characterized in aquifers from eight major groups based on geologic material, including (1) unconsolidated sand and gravel; (2) glacial unconsolidated sand and gravel; (3) semiconsolidated sand; (4) sandstone; (5) sandstone and carbonate rock; (6) carbonate rock; (7) basaltic and other volcanic rock; and (8) crystalline rock. The majority of groundwater samples and the largest percentages of exceedences of HHBs were in the glacial and nonglacial unconsolidated sand and gravel aquifers; in these aquifers, As, Mn, and U are the most common trace elements exceeding HHBs. Overall, 19 percent of wells (962 of 5,097) exceeded an HHB for at least one trace element. The trace elements with HHBs included in this summary were Sb, As, Ba, Be, B, Cd, Cr,

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

Natesan, K.; Momozaki, Y.; Li, M.

This report gives a description of the activities in design, fabrication, construction, and assembling of a pumped sodium loop for the sodium compatibility studies on advanced structural materials. The work is the Argonne National Laboratory (ANL) portion of the effort on the work project entitled, 'Sodium Compatibility of Advanced Fast Reactor Materials,' and is a part of Advanced Materials Development within the Reactor Campaign. The objective of this project is to develop information on sodium corrosion compatibility of advanced materials being considered for sodium reactor applications. This report gives the status of the sodium pumped loop at Argonne National Laboratory,more » the specimen details, and the technical approach to evaluate the sodium compatibility of advanced structural alloys. This report is a deliverable from ANL in FY2010 (M2GAN10SF050302) under the work package G-AN10SF0503 'Sodium Compatibility of Advanced Fast Reactor Materials.' Two reports were issued in 2009 (Natesan and Meimei Li 2009, Natesan et al. 2009) which examined the thermodynamic and kinetic factors involved in the purity of liquid sodium coolant for sodium reactor applications as well as the design specifications for the ANL pumped loop for testing advanced structural materials. Available information was presented on solubility of several metallic and nonmetallic elements along with a discussion of the possible mechanisms for the accumulation of impurities in sodium. That report concluded that the solubility of many metals in sodium is low (<1 part per million) in the temperature range of interest in sodium reactors and such trace amounts would not impact the mechanical integrity of structural materials and components. The earlier report also analyzed the solubility and transport mechanisms of nonmetallic elements such as oxygen, nitrogen, carbon, and hydrogen in laboratory sodium loops and in reactor systems such as Experimental Breeder Reactor-II, Fast Flux Test Facility, and Clinch River Breeder Reactor. Among the nonmetallic elements discussed, oxygen is deemed controllable and its concentration in sodium can be maintained in sodium for long reactor life by using cold-trap method. It was concluded that among the cold-trap and getter-trap methods, the use of cold trap is sufficient to achieve oxygen concentration of the order of 1 part per million. Under these oxygen conditions in sodium, the corrosion performance of structural materials such as austenitic stainless steels and ferritic steels will be acceptable at a maximum core outlet sodium temperature of {approx}550 C. In the current sodium compatibility studies, the oxygen concentration in sodium will be controlled and maintained at {approx}1 ppm by controlling the cold trap temperature. The oxygen concentration in sodium in the forced convection sodium loop will be controlled and monitored by maintaining the cold trap temperature in the range of 120-150 C, which would result in oxygen concentration in the range of 1-2 ppm. Uniaxial tensile specimens are being exposed to flowing sodium and will be retrieved and analyzed for corrosion and post-exposure tensile properties. Advanced materials for sodium exposure include austenitic alloy HT-UPS and ferritic-martensitic steels modified 9Cr-1Mo and NF616. Among the nonmetallic elements in sodium, carbon was assessed to have the most influence on structural materials since carbon, as an impurity, is not amenable to control and maintenance by any of the simple purification methods. The dynamic equilibrium value for carbon in sodium systems is dependent on several factors, details of which were discussed in the earlier report. The current sodium compatibility studies will examine the role of carbon concentration in sodium on the carburization-decarburization of advanced structural materials at temperatures up to 650 C. Carbon will be added to the sodium by exposure of carbon-filled iron tubes, which over time will enable carbon to diffuse through iron and dissolve into sodium. The method enables addition of dissolved carbon (without carbon particulates) in sodium that is of interest for materials compatibility evaluation. The removal of carbon from the sodium will be accomplished by exposing carbon-gettering alloys such as refractory metals that have a high partitioning coefficient for carbon and also precipitate carbides, thereby decreasing the carbon concentration in sodium.« less

Spectroscopic Studies of Pre-Biotic Carbon Chemistry

NASA Technical Reports Server (NTRS)

Blake, Geoffrey A.

2002-01-01

As described in the original proposal and in our progress reports, research in the Blake group supported by the Exobiology program seeks to understand the pre-biotic chemistry of carbon along with that of other first- and second-row elements from the earliest stages of star formation through the development of planetary systems. The major tool used is spectroscopy, and the program has observational, laboratory, and theoretical components. The observational and theoretical programs are concerned primarily with a quantitative assessment of the chemical budgets of the biogenic elements in star-forming molecular cloud cores, while the laboratory work is focused on the complex species that characterize the prebiotic chemistry of carbon. We outline below our results over the past two years acquired, in part, with Exobiology support.

Simulation of the Thermographic Response of Near Surface Flaws in Reinforced Carbon-Carbon Panels

NASA Technical Reports Server (NTRS)

Winfree, William P.; Howell, Patricia A.; Burke, Eric R.

2009-01-01

Thermographic inspection is a viable technique for detecting in-service damage in reinforced carbon-carbon (RCC) composites that are used for thermal protection in the leading edge of the shuttle orbiter. A thermographic technique for detection of near surface flaws in RCC composite structures is presented. A finite element model of the heat diffusion in structures with expected flaw configurations is in good agreement with the experimental measurements.

Low-carbon martensitic steels. Alloying and properties

NASA Astrophysics Data System (ADS)

Kleiner, L. M.; Shatsov, A. A.; Larinin, D. M.

2011-03-01

Requirements on the structure of a steel with structural strength and a set of characteristics higher than those of medium-carbon steels with a structure of tempered sorbite are formulated. Principles for choosing compositions for process-adaptable low-carbon martensitic steels are presented. The combination of carbon and alloying elements providing high stability of austenite in the ranges of normal and intermediate transformations is determined, which makes it possible to obtain lath martensite in slow cooling.

The adsorption of rare earth ions using carbonized polydopamine nano shells

DOE PAGES

Sun, Xiaoqi; Luo, Huimin; Mahurin, Shannon Mark; ...

2016-01-07

Herein we report the structure effects of nano carbon shells prepared by carbonized polydopamine for rare earth elements (REEs) adsorption for the first time. The solid carbon sphere, 60 nm carbon shell and 500 nm carbon shell were prepared and investigated for adsorption and desorption of REEs. The adsorption of carbon shells for REEs was found to be better than the solid carbon sphere. The effect of acidities on the adsorption and desorption properties was discussed in this study. The good adsorption performance of carbon shells can be attributed to their porous structure, large specific surface area, amine group andmore » carbonyl group of dopamine.« less

Spatial/Temporal Variations of Elemental Carbon, Organic Carbon, and Trace Elements in PM10 and the Impact of Land-Use Patterns on Community Air Pollution in Paterson, NJ

PubMed Central

Yu, Chang Ho; Fan, Zhi-Hua; Meng, Qingyu; Zhu, Xianlei; Korn, Leo; Bonanno, Linda J.

2014-01-01

An urban community PM10 (particulate matter ≤ 10 μm in aerodynamic diameter) air pollution study was conducted in Paterson, NJ, a mixed land-use community that is interspersed with industrial, commercial, mobile, and residential land-use types. This paper examines (1) the spatial/temporal variation of PM10, elemental carbon (EC), organic carbon (OC), and nine elements; and (2) the impact of land-use type on those variations. Air samples were collected from three community-oriented locations in Paterson that attempted to capture industrial, commercial, and mobile source-dominated emissions. Sampling was conducted for 24 hr every 6 days from November 2005 through December 2006. Samples were concurrently collected at the New Jersey Department of Environmental Protection-designated air toxics background site in Chester, NJ. PM10 mass, EC, OC, and nine elements (Ca, Cu, Fe, Pb, Mn, Ni, S, Ti, and Zn) that had more than 50% of samples above detection and known sources or are toxic were selected for spatial/temporal analysis in this study. The concentrations of PM10, EC, OC, and eight elements (except S) were significantly higher in Paterson than in Chester (P < 0.05). The concentrations of these elements measured in Paterson were also found to be higher during winter than the other three seasons (except S), and higher on weekdays than on weekends (except Pb). The concentrations of EC, Cu, Fe, and Zn at the commercial site in Paterson were significantly higher than the industrial and mobile sites; however, the other eight species were not significantly different within the city (P > 0.05). These results indicated that anthropogenic sources of air pollution were present in Paterson. The source apportionment confirmed the impact of vehicular and industrial emissions on the PM10 ambient air pollution in Paterson. The multiple linear regression analysis showed that categorical land-use type was a significant predictor for all air pollution levels, explaining up to 42% of the variability in concentration by land-use type only. PMID:21751583

Variability in magnesium, carbon and oxygen isotope compositions, and trace element contents of brachiopod shells: implications for paleoceanographic studies

NASA Astrophysics Data System (ADS)

Rollion-Bard, Claire; Saulnier, Ségolène; Vigier, Nathalie; Schumacher, Aimryc; Chaussidon, Marc; Lécuyer, Christophe

2016-04-01

Magnesium content in the ocean is ≈ 1290 ppm and is one of the most abundant elements. It is involved in the carbon cycle via the dissolution and precipitation of carbonates, especially Mg-rich carbonates as dolomites. The Mg/Ca ratio of the ocean is believed to have changed through time. The causes of these variations, i.e. hydrothermal activity change or enhanced precipitation of dolomite, could be constrained using the magnesium isotope composition (δ26Mg) of carbonates. Brachiopods, as marine environmental proxies, have the advantage to occur worldwide in a depth range from intertidal to abyssal, and have been found in the geological record since the Cambrian. Moreover, as their shell is in low-Mg calcite, they are quite resistant to diagenetic processes. Here we report δ26Mg, δ18O, δ13C values along with trace element contents of one modern brachiopod specimen (Terebratalia transversa) and one fossil specimen (Terebratula scillae, 2.3 Ma). We combined δ26Mg values with oxygen and carbon isotope compositions and trace element contents to look for possible shell geochemical heterogeneities in order to investigate the processes that control the Mg isotope composition of brachiopod shells. We also evaluate the potential of brachiopods as a proxy of past seawater δ26Mg values. The two investigated brachiopod shells present the same range of δ26Mg variation (up to 2 ‰)). This variation cannot be ascribed to changes in environmental parameters, i.e. temperature or pH. As previously observed, the primary layer of calcite shows the largest degree of oxygen and carbon isotope disequilibrium relative to seawater. In contrast, the δ26Mg value of this layer is comparable to that of the secondary calcite layer value. In both T. scillae and T. transversa, negative trends are observable between magnesium isotopic compositions and oxygen and carbon isotopic compositions. These trends, combined to linear relationships between δ26Mg values and REE contents, are best explained by kinetic effects linked to changes in growth rate during the brachiopod life. The innermost calcite layer of T. transversa is in isotopic equilibrium for both oxygen and magnesium and could therefore be the best target for reconstructing past δ26Mg values of seawater.

Artificial topography changes the growth strategy of Spartina alterniflora, case study with wave exposure as a comparison.

PubMed

Hong, Hualong; Dai, Minyue; Lu, Haoliang; Liu, Jingchun; Zhang, Jie; Chen, Chaoqi; Xia, Kang; Yan, Chongling

2017-11-17

This paper reports findings about the growth of Spartina alterniflora (Loisel.) near an engineered coastal protection defences to discover the potential influences on vegetation growth from the artificial topography. Impacts of the artificial topography on the sediment element composition were detected by comparing the fixed effects caused by artificial topography and wave exposure using linear mixed models. Surficial sediments under the impacts of artificial topography contain elevated levels of biogenic elements and heavy metals, including C (and organic carbon), N, S, Al, Fe, Mn, Cu, Zn, As, Cd, Cr, Ni, and Pb. The results showed that element enrichment caused by artificial topography reduced the vegetation sexual reproduction. Contrary to the potential inhibition caused by direct wave exposure, which was due to the biomass accumulation limit, the inhibition caused by artificial topography was related to the transition of growth strategy. The contents of Cu, Mn, N, Ni, S and As in the sediments were critical in considering the relationship between the change in the sediment element composition and the alteration in the plant growth. Our study emphasizes the importance of rethinking the impacts of coastal development projects, especially regarding the heterogeneity of sediment element composition and its ecological consequences.

Atmosphere stabilization and element recycle in an experimental mouse-algal system

NASA Technical Reports Server (NTRS)

Smernoff, David T.

1986-01-01

Life support systems based on bioregeneration rely on the control and manipulation of organisms. Experiments conducted with a gas-closed mouse-algal system designed to investigate principles of photosynthetic gas exchange focus primarily on observing gas exchange phenomena under varying algal environmental conditions and secondarily on studying element cycling through compartments of the experimental system. Inherent instabilities exit between the uptake and release of carbon dioxide CO2 and oxygen O2 by the mouse and algae. Variations in light intensity and cell density alter the photosynthetic rate of the algae and enable maintenance of physiologic concentrations of CO2 and O2. Different nitrogen sources (urea and nitrate) result in different algal assimilatory quotients (AQ). Combinations of photosynthetic rate and AQ ratio manipulations have been examined for their potential in stabilizing atmospheric gas concentrations in the gas-closed algal-mouse system. Elemental mass balances through the experimental systems compartments are being studied with the concurrent development of a mathematical simulation model. Element cycling experiments include quantification of elemental flows through system compartments and wet oxidation of system waste materials for use as an algal nutrient source. Oxidized waste products demonstrate inhibitory properties although dilution has been shown to allow normal growth.

Comparation of Organic and Elemental carbon concentrations in PM2.5 in five Mexican cities: Potencial Sources

NASA Astrophysics Data System (ADS)

Herrera Murillo, J.; Cardenas, B.; Campos-Ramos, A.; Blanco-Jimenez, S.; Angeles-Garcia, F.

2011-12-01

During 2006-2010 the National Center for Environmental Research and Training of the National Institute of Ecology of Mexico, carried out several short field studies in the cities of Salamanca, Gto, Tula, Hgo; Guadalajara, Jal; Toluca, Edo Mex; and Tijuana, BC to determine concentration and chemical compositions of PM2.5. These cities, although different in size population have all important industrial and area sources that contribute to high PM2.5 concentrations and therefore potential health impacts. Chemical analyses included organic and elemental carbon for which DRI Model 2001 Thermal/Optical Carbon Analyzer (Atmoslytic Inc, Calabasas, CA, USA) was used. Highest PM2.5 mass mean concentrations were obtained in Salamanca (46 μg/m3), followed by Toluca (43 μg/m3), Guadalajara (37 μg/m3), Tula (20 μg/m3) and Tijuana (18 μg/m3). For Salamanca and Tula, annual levels exceeded the Mexican PM2.5 annual standard of 15 μg/m3. Total carbonaceous aerosol accounted for 41.4%, 41.1%, 32.3%, 29.5% and 29.1% of PM2.5 mass in Tula, Toluca, Guadalajara, Salamanca and Tijuana, respectively. Higher OC2, OC3 and OC4 carbon fractions were observed in Guadalajara, Tijuana and Toluca, indicating an important contribution of gasoline and diesel vehicles emissions in these cities. As for Tula and Salamanca, cities in which refineries and power plants are present, OC3, OC4, EC1 and EC2 represent the higher fractions which could be attributed to stationary sources that use heavy fuels for their combustion process. UNMIX and PMF analyses were used in order to identify the most important sources that contributes to OC and EC concentrations.

Numerical study on seasonal variations of gaseous pollutants and particulate matters in Hong Kong/Pearl River Delta Region

NASA Astrophysics Data System (ADS)

Kwok, Roger Hiu Fung

Air pollution in Hong Kong (HK) causes problems in visibility and public health, which are worsening over past few years. Out of particulate matters (PM) inhalable into respiratory system, 30% is contributed by sulfate (SO4), 40% by organic carbon (OC), and 10% by elemental carbon (EC). A meso-scale numerical modeling system CMAQ is devised to simulate the air quality in January (winter), April (spring), July (summer) and October (autumn) 2004, driven by meteorology simulated by MM5 and emission sources in China including Hong Kong. Observational and measurement data from Hong Kong Environmental Protection Department Air Quality network are compared with the model results. With respect to pollutant concentration level, model-observation agreement is reasonably well, especially in PM species sulfate, organic carbon (OC) and elemental carbon (EC); and gaseous species SO2, NOx and ozone. In terms of PM composition, the model agrees with the measurement in fractions of sulfate, OC and EC. Higher PM level in autumn and winter is associated with northeasterly winds due to continental outflow. To further investigate emission sources contributing to HK, a source apportioning method called Tagged Species Source Apportionment (TSSA) algorithm is applied to study contributions to level of SO4, SO2 and EC in HK. It is found that while sources beyond PRD are observed in entire HK during January and October 2004, emitting sectors are different among western HK, downtown area, and the east countryside. Specifically, power plants and vehicles from HK and Shenzhen affect the western new towns, while power plants, vehicles and ships within HK determine the downtown pollutants' level. The countryside is mainly influenced by sources beyond PRD.

Finned Carbon-Carbon Heat Pipe with Potassium Working Fluid

NASA Technical Reports Server (NTRS)

Juhasz, Albert J.

2010-01-01

This elemental space radiator heat pipe is designed to operate in the 700 to 875 K temperature range. It consists of a C-C (carbon-carbon) shell made from poly-acrylonitride fibers that are woven in an angle interlock pattern and densified with pitch at high process temperature with integrally woven fins. The fins are 2.5 cm long and 1 mm thick, and provide an extended radiating surface at the colder condenser section of the heat pipe. The weave pattern features a continuous fiber bath from the inner tube surface to the outside edges of the fins to maximize the thermal conductance, and to thus minimize the temperature drop at the condenser end. The heat pipe and radiator element together are less than one-third the mass of conventional heat pipes of the same heat rejection surface area. To prevent the molten potassium working fluid from eroding the C C heat pipe wall, the shell is lined with a thin-walled, metallic tube liner (Nb-1 wt.% Zr), which is an integral part of a hermetic metal subassembly which is furnace-brazed to the inner surface of the C-C tube. The hermetic metal liner subassembly includes end caps and fill tubes fabricated from the same Nb-1Zr alloy. A combination of laser and electron beam methods is used to weld the end caps and fill tubes. A tungsten/inert gas weld seals the fill tubes after cleaning and charging the heat pipes with potassium. The external section of this liner, which was formed by a "Uniscan" rolling process, transitions to a larger wall thickness. This section, which protrudes beyond the C-C shell, constitutes the "evaporator" part of the heat pipe, while the section inside the shell constitutes the condenser of the heat pipe (see figure).

TIC/TOC and Redox Sensitive Trace Element (RSTEs) Signals Indicating Redox Conditions of the Lower Part of the Cabo Formation Near Organya (Organya Basin), Catalunya, Spain

NASA Astrophysics Data System (ADS)

Herdocia, C.; Maurrasse, F. J.

2017-12-01

The thick (> 4.5 km) sedimentary succession of the Organya Basin includes the Cabo Formation [1] which is well exposed in the Cabo valley area and is characteristically composed of black to dark gray marlstones and limestones that accumulated during the greenhouse climate and contain variable amount of organic matter [2-4]. Here we present geochemical results to assess redox conditions of 35.6 m of the Cabo Formation near the Barremian / Aptian boundary, along Catalunya Route C-14, immediately north of the town of Organya. TOC values range between 1 wt% and 5.8 wt%, and peak in all black limestones (0.43 m, 4.38 m, 14.85 m, 29.95 m, and 35.6 m). These TOC values average about 2.0 wt %, except at a height of 0.43 m, where the TOC has a strong peak (5.78 wt%). TIC values oscillated between 86.7 wt% and 96.8 wt%, and averaged at 92.7 wt% and show a strong negative correlation with TOC (r = -0.78). Measured carbon isotope on the organic carbon fraction (δ13Corg) showed fluctuations that ranged from -24.41‰ to -22.15‰. The TOC and δ13Corg curves show a positive correlation (r = 0.58), suggesting that carbon sequestration in the basin followed the overall global signature. Redox sensitive trace elements (V, Ni, Cu, and Mo) correlate with TOC values (r > 0.6), suggesting that dysoxic conditions were responsible for the preservation of organic matter. Biolimiting trace elements (Fe, P) also correlate positively with redox trace elements, and both have highest concentrations at 14.85 m, in concurrence with a high TOC value (2.93 wt%) indicating high primary productivity at that level. Major elements (Al, Si, and Ti) also correlates slightly with TOC (Al: r = 0.39; Si: r = 0.36; Ti: r = 0.43). References: [1] García-Senz, J., 2002, PhD Thesis, University of Barcelona, 310 pp. [2] Bernaus, J.M., et al., 2003. Sedimentary Geology 159 (3-4), 177-201. [3] Caus, E., et al., 1990. Cret. Research 11, 313-320. [4] Sanchez-Hernandez, Y., Maurrasse, F.J-M.R. 2014. Chem.Geology 372, 12-31.

Forming aspheric optics by controlled deposition

DOEpatents

Hawryluk, A.M.

1998-04-28

An aspheric optical element is disclosed formed by depositing material onto a spherical surface of an optical element by controlled deposition to form an aspheric surface of desired shape. A reflecting surface, single or multi-layer, can then be formed on the aspheric surface by evaporative or sputtering techniques. Aspheric optical elements are suitable for deep ultra-violet (UV) and x-ray wavelengths. The reflecting surface may, for example, be a thin ({approx}100 nm) layer of aluminum, or in some cases the deposited modifying layer may function as the reflecting surface. For certain applications, multi-layer reflective surfaces may be utilized, such as chromium-carbon or tungsten-carbon multi-layer, with the number of layers and thickness being determined by the intended application. 4 figs.

Forming aspheric optics by controlled deposition

DOEpatents

Hawryluk, Andrew M.

1998-01-01

An aspheric optical element formed by depositing material onto a spherical surface of an optical element by controlled deposition to form an aspheric surface of desired shape. A reflecting surface, single or multi-layer, can then be formed on the aspheric surface by evaporative or sputtering techniques. Aspheric optical elements are suitable for deep ultra-violet (UV) and x-ray wavelengths. The reflecting surface may, for example, be a thin (.about.100 nm) layer of aluminum, or in some cases the deposited modifying layer may function as the reflecting surface. For certain applications, multi-layer reflective surfaces may be utilized, such as chromium-carbon or tungsten-carbon multi-layer, with the number of layers and thickness being determined by the intended application.

Soot on snow in Iceland: First results on black carbon and organic carbon in Iceland 2016 snow and ice samples, including the glacier Solheimajökull

NASA Astrophysics Data System (ADS)

Meinander, Outi; Dagsson-Waldhauserova, Pavla; Gritsevich, Maria; Aurela, Minna; Arnalds, Olafur; Dragosics, Monika; Virkkula, Aki; Svensson, Jonas; Peltoniemi, Jouni; Kontu, Anna; Kivekäs, Niku; Leppäranta, Matti; de Leeuw, Gerrit; Laaksonen, Ari; Lihavainen, Heikki; Arslan, Ali N.; Paatero, Jussi

2017-04-01

New results on black carbon (BC) and organic carbon (OC) on snow and ice in Iceland in 2016 will be presented in connection to our earlier results on BC and OC on Arctic seasonal snow surface, and in connection to our 2013 and 2016 experiments on effects of light absorbing impurities, including Icelandic dust, on snow albedo, melt and density. Our sampling included the glacier Solheimajökull in Iceland. The mass balance of this glacier is negative and it has been shrinking during the last 20 years by 900 meters from its southwestern corner. Icelandic snow and ice samples were not expected to contain high concentrations of BC, as power generation with domestic renewable water and geothermal power energy sources cover 80 % of the total energy consumption in Iceland. Our BC results on filters analyzed with a Thermal/Optical Carbon Aerosol Analyzer (OC/EC) confirm this assumption. Other potential soot sources in Iceland include agricultural burning, industry (aluminum and ferroalloy production and fishing industry), open burning, residential heating and transport (shipping, road traffic, aviation). On the contrary to low BC, we have found high concentrations of organic carbon in our Iceland 2016 samples. Some of the possible reasons for those will be discussed in this presentation. Earlier, we have measured and reported unexpectedly low snow albedo values of Arctic seasonally melting snow in Sodankylä, north of Arctic Circle. Our low albedo results of melting snow have been confirmed by three independent data sets. We have explained these low values to be due to: (i) large snow grain sizes up to 3 mm in diameter (seasonally melting snow); (ii) meltwater surrounding the grains and increasing the effective grain size; (iii) absorption caused by impurities in the snow, with concentration of elemental carbon (black carbon) in snow of 87 ppb, and organic carbon 2894 ppb. The high concentrations of carbon were due to air masses originating from the Kola Peninsula, Russia, where mining and refining industries are located. SNICAR-model showed that the impurities absorb irradiance the more the shorter the wavelength. We have also presented a hypothesis that soot can decrease the liquid-water retention capacity of melting snow. There we also presented data, where both the snow density and elemental carbon content were measured. In our snow density related experiments, artificially added light-absorbing impurities decreased the density of seasonally melting natural snow. No relationship was found in case of natural non-melting snow. Our experimental results on Icelandic volcanic ash have showed that Eyjafjällajökull ash with grain size smaller than 500 μm insulated the ice below at a thickness of 9-15 mm (called as 'critical thickness'). For the 90 μm grain size, the insulation thickness was 13 mm. The maximum melt occurred at thickness of 1mm for the larger particles, and at the thickness of < 1-2 mm for the smaller particles (called as 'effective thickness'). Earlier, similar threshold dust layer thickness values have been given for Mt St Helens (1980) ash, and Hekla (1947) tephra, but our results were the first ones reported for the Eyjafjällajökull ash. In Iceland, the dust layers in the nature can be from mm scale up to tens of meters. Our results clearly demonstrate how important it is in the Arctic to perform measurements of BC, OC, and dust in the snow to fully understand the effects of light absorbing impurities on the cryosphere.

Chemical analysis of water samples and geophysical logs from cored test holes drilled in the central Oklahoma Aquifer, Oklahoma

USGS Publications Warehouse

Schlottmann, Jamie L.; Funkhouser, Ron A.

1991-01-01

Chemical analyses of water from eight test holes and geophysical logs for nine test holes drilled in the Central Oklahoma aquifer are presented. The test holes were drilled to investigate local occurrences of potentially toxic, naturally occurring trace substances in ground water. These trace substances include arsenic, chromium, selenium, residual alpha-particle activities, and uranium. Eight of the nine test holes were drilled near wells known to contain large concentrations of one or more of the naturally occurring trace substances. One test hole was drilled in an area known to have only small concentrations of any of the naturally occurring trace substances.Water samples were collected from one to eight individual sandstone layers within each test hole. A total of 28 water samples, including four duplicate samples, were collected. The temperature, pH, specific conductance, alkalinity, and dissolved-oxygen concentrations were measured at the sample site. Laboratory determinations included major ions, nutrients, dissolved organic carbon, and trace elements (aluminum, arsenic, barium, beryllium, boron, cadmium, chromium, hexavalent chromium, cobalt, copper, iron, lead, lithium, manganese, mercury, molybdenum, nickel, selenium, silver, strontium, vanadium and zinc). Radionuclide activities and stable isotope (5 values also were determined, including: gross-alpha-particle activity, gross-beta-particle activity, radium-226, radium-228, radon-222, uranium-234, uranium-235, uranium-238, total uranium, carbon-13/carbon-12, deuterium/hydrogen-1, oxygen-18/oxygen-16, and sulfur-34/sulfur-32. Additional analyses of arsenic and selenium species are presented for selected samples as well as analyses of density and iodine for two samples, tritium for three samples, and carbon-14 for one sample.Geophysical logs for most test holes include caliper, neutron, gamma-gamma, natural-gamma logs, spontaneous potential, long- and short-normal resistivity, and single-point resistance. Logs for test-hole NOTS 7 do not include long- and short-normal resistivity, spontaneous-potential, or single-point resistivity. Logs for test-hole NOTS 7A include only caliper and natural-gamma logs.