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Sample records for lead carbonates

  1. 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.

  2. Lead carbonate scintillator materials

    DOEpatents

    Derenzo, S.E.; Moses, W.W.

    1991-05-14

    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. 3 figures.

  3. Nucleation and electrolytic deposition of lead on model carbon electrodes

    NASA Astrophysics Data System (ADS)

    Cericola, D.; Spahr, M.

    2016-08-01

    There is a general consensus in the lead acid battery industry for the use of carbon additives as a functional component in the negative paste to boost the battery performance with regards to charge acceptance and cycle life especially for upcoming automotive and energy storage applications. Several mechanisms are discussed in the scientific literature and the affinity of the carbon surfaces to lead species seems to play a key role. With a set of experiments on model carbon electrodes we gave evidence to the fact that some carbon materials promote spontaneous nucleation of lead crystals. We propose a mechanism such that the carbon, as soon as in a lead containing environment, immobilizes some lead on its surface. Such immobilized lead acts as nucleation seed for the deposition of lead when a current is passed through the material. It is therefore possible to differentiate and select the carbon materials based on their ability to form nucleation seeds.

  4. Removing lead in drinking water with activated carbon

    SciTech Connect

    Taylor, R.M.; Kuennen, R.W. )

    1994-02-01

    A point-of-use (POU) granular activated carbon (GAC) fixed bed adsorber (FBA) was evaluated for reduction of soluble and insoluble lead from drinking water. Some of the factors which affect lead removal by GAC were evaluated, such as carbon type, solution pH, and a limited amount of work on competitive interactions. The design criteria for lead reduction by a POU device are also addressed. Minicolumns were used to evaluate the capacity of carbon for lead under a variety of conditions. The importance of surface chemistry of the carbon and the relationship with the pH of the water for lead reduction was demonstrated. Results indicate that a properly designed POU-GAC-FBA can reduce lead in drinking water to below the EPA action level of 15 ppb while being tested under a variety of conditions as specified under the National Sanitation Foundation (NSF) International Standard 53 test protocol. 37 refs., 9 figs., 1 tab.

  5. A new carbon structure in annealed film coatings of the carbon-lead system

    NASA Astrophysics Data System (ADS)

    Volodin, V. N.; Tuleushev, Yu. Zh.; Zhakanbaev, E. A.; Tsai, K. V.; Rofman, O. V.

    2017-01-01

    Carbon-lead solid solutions coexisting with amorphous carbon have been obtained for the first time in a film coating deposited by ion-plasma sputtering. During subsequent vacuum annealing of carbon-lead films containing more than 68.5 at % Pb, this element almost completely evaporates to leave an amorphous carbon coating on a substrate. During annealing at 1100°C, this amorphous carbon crystallizes into a new hexagonal lattice with unit cell parameters a = 0.7603 nm and c = 0.8168 nm. Characteristic X-ray diffraction data for the identification of this phase are determined.

  6. Characterization of nano-lead-doped active carbon and its application in lead-acid battery

    NASA Astrophysics Data System (ADS)

    Hong, Bo; Jiang, Liangxing; Xue, Haitao; Liu, Fangyang; Jia, Ming; Li, Jie; Liu, Yexiang

    2014-12-01

    In this paper, nano-lead-doped active carbon (nano-Pb/AC) composite with low hydrogen evolution current for lead-acid battery was prepared by ultrasonic-absorption and chemical-precipitate method. The nano-Pb/AC composite was characterized by SEM, EDS and TEM. The electrochemical characterizations are performed by linear sweep voltammetry (LSV), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) in a three-electrode system. Since intermediate adsorption is the rate-determining step, the hydrogen evolution reaction (HER) is markedly inhibited as the intermediate adsorption impedance of nano-Pb/AC increased. Meanwhile, the working potential of nano-Pb/AC is widened to the whole potential region of Pb negative plate (from -1.36 V to -0.86 V vs. Hg/HgSO4) in lead-acid battery. In addition, nano-Pb can improve the interfacial compatibility between AC and Pb paste, accordingly relieve the symptoms of carbon floatation. Finally, 2.0 V single-cell flooded lead-acid batteries with 1.0 wt.% nano-Pb/AC or 1.0 wt.% AC addition in negative active materials are assembled. The cell performances test results show that the 3 h rate capacity, quick charging performance, high current discharging performance and cycling performance of nano-Pb/AC modified battery are all improved compared with regular lead-acid battery and AC modified lead-acid battery.

  7. Carbon nanotubes enhanced the lead toxicity on the freshwater fish

    NASA Astrophysics Data System (ADS)

    Martinez, D. S. T.; Alves, O. L.; Barbieri, E.

    2013-04-01

    Carbon nanotubes are promising nanostructures for many applications in materials industry and biotechnology. However, it is mandatory to evaluate their toxicity and environmental implications. We evaluated nitric acid treated multiwalled carbon nanotubes (HNO3-MWCNT) toxicity in Nile tilapia (Oreochromis niloticus) and also the lead (Pb) toxicity modulation after the nanotube interaction. Industrial grade multiwalled carbon nanotubes [Ctube 100, CNT Co. Ltd] were treated with 9M HNO3 for 12h at 150°C to generate oxygenated groups on the nanotube surface, to improve water dispersion and heavy metal interaction. The HNO3-treated multiwalled carbon nanotubes were physico-chemically characterized by several techniques [e.g. TEM, FE-SEM, TGA, ζ-potential and Raman spectroscopy]. HNO3-MWCNT did not show toxicity on Nile tilapia when the concentration ranged from 0.1 to 3.0 mg/L, and the maximum exposure time was 96h. After 24, 48, 72 and 96h the LC50 values of Pb were 1.65, 1.32, 1.10 and 0.99 mg/L, respectively. To evaluate the Pb-nanotube interaction influence on the ecotoxicity, we submitted the Nile tilapia to different concentrations of Pb mixed with a non-toxic concentration of HNO3-MWCNT (1.0 mg/L). After 24, 48, 72, 96 h the LC50 values of Pb plus nanotubes were: 0.32, 0.25, 0.20, 0.18 mg/L, respectively. These values showed a synergistic effect after Pb-nanotube interaction since Pb toxicity increased over five times. X-ray energy dispersive spectroscopy (EDS) was used to confirm lead adsorption on the carbon nanotube oxidized surface. The exposure of Nile tilapia to Pb plus HNO3-MWCNT caused both oxygen consumption and ammonium excretion decrease, when compared to the control. Finally, our results show that carbon nanotubes interact with classical pollutants drawing attention to the environmental implications.

  8. Does increasing rotation length lead to greater forest carbon storage?

    NASA Astrophysics Data System (ADS)

    Ter-Mikaelian, M. T.; Colombo, S. J.; Chen, J.

    2016-12-01

    Forest management is a key factor affecting climate change mitigation by forests. Increasing the age of harvesting (also referred to as rotation length) is a management practice that has been proposed as a means of increasing forest carbon sequestration and storage. However, studies of the effects of increasing harvest age on forest carbon stocks have mostly been limited to forest plantations. In contrast, this study assesses the effects of increased harvest age of managed natural forests of Ontario (Canada) at two scales. At the stand level, we assess merchantable volume yield curves to differentiate those for which increasing the age of harvest results in an increase in total forest carbon stocks versus those for which increased harvest age reduces carbon stocks. The stand level results are then applied to forest landscapes to demonstrate that the effect of increasing the age of harvest on forest carbon storage is specific to the forest growth rates for a given forest landscape and depends on the average age at which forests are harvested under current (business-as-usual) management practice. We discuss the implications of these results for forest management aimed at mitigating climate change.

  9. 4.4.4 R1 and R2: Leading atom other than carbon; R3: Leading atom carbon

    NASA Astrophysics Data System (ADS)

    Beckwith, A. L. J.

    This document is part of Subvolume A1 `Inorganic Radicals, Metal Complexes and Nonconjugated Carbon Centered Radicals' of Volume 26 `Magnetic Properties of Free Radicals' of Landolt-Börnstein Group II `Molecules and Radicals'.

  10. Preliminary thermal/structural analysis of a carbon-carbon/refractory-metal heat-pipe-cooled wing leading edge

    NASA Technical Reports Server (NTRS)

    Glass, David E.; Camarda, Charles J.

    1990-01-01

    This study presents preliminary thermal/structural analyses of a carbon-carbon/refractory-metal heat-pipe-cooled wing leading edge concept designed for an air breathing single-stage-to-orbit hypersonic vehicle. The concept features chordwise (i.e., normal to the leading edge) and spanwise (i.e., parallel to the leading edge) refractory-metal heat pipes which are completely embedded within a carbon-carbon primary structure. Studies of the leading edge were performed using nonlinear thermal and linear structural three-dimensional finite element analyses. The concept was shown to be thermally feasible within the limits of the assumptions made in the analyses when internal radiative cooling is present during ascent, and a three-dimensional carbon-carbon architecture is used. In addition, internal radiative cooling was found not to be necessary during descent. The linear stress analysis indicated excessively large thermal stresses in the rafractory metal walls of the heat pipes even though a soft layer of carbon was included between the heat pipe and the carbon-carbon structure in an attempt to reduce the thermal stresses. A nonlinear structural analysis may be necessary to properly model the response of the refractory-metal heat pipes.

  11. Metallic Concepts for Repair of Reinforced Carbon-Carbon Space Shuttle Leading Edges

    NASA Technical Reports Server (NTRS)

    Ritzert, Frank; Nesbitt, James

    2007-01-01

    The Columbia accident has focused attention on the critical need for on-orbit repair concepts for wing leading edges in the event that potentially catastrophic damage is incurred during Space Shuttle Orbiter flight. The leading edge of the space shuttle wings consists of a series of eleven panels on each side of the orbiter. These panels are fabricated from reinforced carbon-carbon (RCC) which is a light weight composite with attractive strength at very high temperatures. The damage that was responsible for the loss of the Colombia space shuttle was deemed due to formation of a large hole in one these RCC leading edge panels produced by the impact of a large piece of foam. However, even small cracks in the RCC are considered as potentially catastrophic because of the high temperature re-entry environment. After the Columbia accident, NASA has explored various means to perform on-orbit repairs in the event that damage is sustained in future shuttle flights. Although large areas of damage, such as that which doomed Columbia, are not anticipated to re-occur due to various improvements to the shuttle, especially the foam attachment, NASA has also explored various options for both small and large area repair. This paper reports one large area repair concept referred to as the "metallic over-wrap." Environmental conditions during re-entry of the orbiter impose extreme requirements on the RCC leading edges as well as on any repair concepts. These requirements include temperatures up to 3000 F (1650 C) for up to 15 minutes in the presence of an extremely oxidizing plasma environment. Figure 1 shows the temperature profile across one panel (#9) which is subject to the highest temperatures during re-entry. Although the RCC possesses adequate mechanical strength at these temperatures, it lacks oxidation resistance. Oxidation protection is afforded by converting the outer layers of the RCC to SiC by chemical vapor deposition (CVD). At high temperatures in an oxidizing

  12. Lead

    MedlinePlus

    ... EPA United States Environmental Protection Agency Search Search Lead Contact Us Share Lead Poisoning is Preventable If your home was built ... to protect people from harmful lead exposures. Less Lead in Drinking Water = Better Health Learn about the ...

  13. Enhancing the performance of lead-acid batteries with carbon - In pursuit of an understanding

    NASA Astrophysics Data System (ADS)

    Moseley, Patrick T.; Rand, David A. J.; Peters, Ken

    2015-11-01

    The inherently poor dynamic charge-acceptance of the lead-acid battery can be greatly improved by the incorporation of additional carbon to the negative plate. An analysis is undertaken of the various ways by which the carbon may be introduced, and of the proposed mechanisms whereby its presence proves to be beneficial. It is intended that such an investigation should provide a guide to the selection of the optimum carbon inventory.

  14. Lead Development of Thiazolylsulfonamides with Carbonic Anhydrase Inhibitory Action.

    PubMed

    Carta, Fabrizio; Birkmann, Alexander; Pfaff, Tamara; Buschmann, Helmut; Schwab, Wilfried; Zimmermann, Holger; Maresca, Alfonso; Supuran, Claudiu T

    2017-03-17

    A series of congeners structurally related to pritelivir, N-[5-(aminosulfonyl)-4-methyl-1,3-thiazol-2-yl]-N-methyl-2-[4-(2-pyridinyl)phenyl]acetamide, a helicase-primase inhibitor for the treatment of herpes simplex virus infections, was prepared. The synthesized primary and secondary sulfonamides were investigated as inhibitors of six physiologically and pharmacologically relevant human (h) carbonic anhydrase (hCA, EC 4.2.1.1) isoforms, the cytosolic enzymes hCA I and II, the mitochondrial ones hCA VA and VB, and the transmembrane, tumor associated hCA IX and XII. Low nanomolar inhibition KI values were detected for all of them, with a very interesting and well-defined structure-activity relationship. As many CAs are involved in serious pathologies, among which are cancer, obesity, epilepsy, glaucoma, etc., sulfonamide inhibitors as those reported here may be of interest as drug candidates. Furthermore, pritelivir itself is an effective inhibitor of some CAs, also inhibiting whole blood enzymes from several mammalian species, which may be a favorable pharmacokinetic feature of the drug which can be transported throughout the body bound to blood CA I and II.

  15. Development of Large Capacity Lead-Carbon Hybrid Ultracapacitors for Energy Storage

    DTIC Science & Technology

    2012-07-01

    storage devices. Among various hybrid ultraultracapacitors, PbO2 ? Activated Carbon is an attractive system owing to its high cell voltage that...provides it both high energy and power densities. In this project, we have designed and developed 12V / kF-range Lead-Carbon (LC) HUCs with absorbent-glass...electrode. 15. SUBJECT TERMS ultra capacitors, ultra capacitors, power storage, power storage, Magneto-optical imaging , Magneto-optical imaging , lead

  16. Altered soil microbial community at elevated CO2 leads to loss of soil carbon

    PubMed Central

    Carney, Karen M.; Hungate, Bruce A.; Drake, Bert G.; Megonigal, J. Patrick

    2007-01-01

    Increased carbon storage in ecosystems due to elevated CO2 may help stabilize atmospheric CO2 concentrations and slow global warming. Many field studies have found that elevated CO2 leads to higher carbon assimilation by plants, and others suggest that this can lead to higher carbon storage in soils, the largest and most stable terrestrial carbon pool. Here we show that 6 years of experimental CO2 doubling reduced soil carbon in a scrub-oak ecosystem despite higher plant growth, offsetting ≈52% of the additional carbon that had accumulated at elevated CO2 in aboveground and coarse root biomass. The decline in soil carbon was driven by changes in soil microbial composition and activity. Soils exposed to elevated CO2 had higher relative abundances of fungi and higher activities of a soil carbon-degrading enzyme, which led to more rapid rates of soil organic matter degradation than soils exposed to ambient CO2. The isotopic composition of microbial fatty acids confirmed that elevated CO2 increased microbial utilization of soil organic matter. These results show how elevated CO2, by altering soil microbial communities, can cause a potential carbon sink to become a carbon source. PMID:17360374

  17. Effect of carbonate ion on precipitation treatment of cadmium, copper, lead and zinc

    SciTech Connect

    Patterson, J.W.

    1982-01-01

    Waste water characteristics and their impact on the susceptibility of the waste to treatment are discussed. Many incidental or added constituents of a wastewater may affect the susceptibility of a metal in that wastewater to precipitation treatment. Among those constituents which may be widely variable with respect to both time and geographical location of an industrial facility, and which can influence precipitation efficiency, is the carbonate alkalinity initially present in the wastewater, or induced into the wastewater as a result of high wastewater treatment pH and consequent uptake of atmospheric CO/sub 2/. Higher carbonate levels may have either an adverse or beneficial effect upon precipitate solubility, depending upon the particular metal and associated pH of precipitation treatment. This effect can be predicted from theoretical calculations, although the actual solubility level may differ from that predicted. With regard to cadmium, both theory and experimental results indicate a reduction in cadmium solubility with increasing carbonate, at treatment pH values below ph 11. on the basis of thermodynamic calculations, added carbonate is predicted to increase copper solubility. Theory predicts a tremendous reduction in lead solubility at trace levels of carbonate at all ph values below pH 12. The effect of carbonate on lead solubility becomes more complex, however, as carbonate level increases. At a treatment pH near 9, increased carbonate is predicted to increase lead solubility, while the reverse patten is predicted at pH near 6. These trends were confirmed by the experimental results.

  18. Discrete carbon nanotubes increase lead acid battery charge acceptance and performance

    NASA Astrophysics Data System (ADS)

    Swogger, Steven W.; Everill, Paul; Dubey, D. P.; Sugumaran, Nanjan

    2014-09-01

    Performance demands placed upon lead acid batteries have outgrown the technology's ability to deliver. These demands, typically leading to Negative Active Material (NAM) failure, include: short, high-current surges; prolonged, minimal, overvoltage charging; repeated, Ah deficit charging; and frequent deep discharges. Research shows these failure mechanisms are attenuated by inclusion of carbon allotropes into the NAM. Addition of significant quantities of carbon, however, produces detrimental changes in paste rheology, leading to lowered industrial throughput. Additionally, capacity, cold-cranking performance, and other battery metrics are negatively affected at high carbon loads. Presented here is Molecular Rebar® Lead Negative, a new battery additive comprising discrete carbon nanotubes (dCNT) which uniformly disperse within battery pastes during mixing. NS40ZL batteries containing dCNT show enhanced charge acceptance, reserve capacity, and cold-cranking performance, decreased risk of polarization, and no detrimental changes to paste properties, when compared to dCNT-free controls. This work focuses on the dCNT as NAM additives only, but early-stage research is underway to test their functionality as a PAM additive. Batteries infused with Molecular Rebar® Lead Negative address the needs of modern lead acid battery applications, produce none of the detrimental side effects associated with carbon additives, and require no change to existing production lines.

  19. Chemically and biologically modified activated carbon sorbents for the removal of lead ions from aqueous media.

    PubMed

    Mahmoud, Mohamed E; Abdel-Fattah, Tarek M; Osman, Maher M; Ahmed, Somia B

    2012-01-01

    A method is described for hybridization of the adsorption and biosorption characteristics of chemically treated commercial activated carbon and baker's yeast, respectively, for the formation of environmental friendly multifunctional sorbents. Activated carbon was loaded with baker's yeast after acid-base treatment. Scanning Electron Microscopy (SEM) and Fourier Transform Infrared (FTIR) Spectroscopy were used to characterize these sorbents. Moreover, the sorption capabilities for lead (II) ions were evaluated. A value of 90 μmol g(-1) was identified as the maximum sorption capacity of activated carbon. Acid-base treatment of activated carbon was found to double the sorption capacity (140-180 μmol g(-1)). Immobilization of baker's yeast on the surface of activated carbon sorbents was found to further improve the sorption capacity efficiency of lead to 360, 510 and 560 μmol g(-1), respectively. Several important factors such as pH, contact time, sorbent dose, lead concentration and interfering ions were examined. Lead sorption process was studied and evaluated by several adsorption isotherms and found to follow the Langmuir and BET models. The potential applications of various chemically and biologically modified sorbents and biosorbents for removal of lead from real water matrices were also investigated via multistage micro-column technique and the results referred to excellent recovery values of lead (95.0-99.0 ± 3.0-5.0 %).

  20. Carbon honeycomb grids for advanced lead-acid batteries. Part III: Technology scale-up

    NASA Astrophysics Data System (ADS)

    Kirchev, A.; Serra, L.; Dumenil, S.; Brichard, G.; Alias, M.; Jammet, B.; Vinit, L.

    2015-12-01

    The carbon honeycomb grid technology employs new carbon/carbon composites with ordered 3D structure instead of the classic lead-acid battery current collectors. The technology is laboratory scaled up from small size grids corresponding to electrodes with a capacity of 3 Ah to current collectors suitable for assembly of lead-acid batteries covering the majority of the typical lead-acid battery applications. Two series of 150 grids each (one positive and one negative) are manufactured using low-cost lab-scale equipment. They are further subjected to pasting with active materials and the resulting battery plates are assembled in 12 V AGM-VLRA battery mono-blocks for laboratory testing and outdoor demonstration in electric scooter replacing its original VRLAB pack. The obtained results demonstrate that the technology can replace successfully the state of the art negative grids with considerable benefits. The use of the carbon honeycomb grids as positive plate current collectors is limited by the anodic corrosion of the entire structure attacking both the carbon/carbon composite part and the electroplated lead-tin alloy coating.

  1. Incorrectly Interpreting the Carbon Mass Balance Technique Leads to Biased Emissions Estimates from Global Vegetation Fires

    NASA Astrophysics Data System (ADS)

    Surawski, N. C.; Sullivan, A. L.; Roxburgh, S. H.; Meyer, M.; Polglase, P. J.

    2016-12-01

    Vegetation fires are a complex phenomenon and have a range of global impacts including influences on climate. Even though fire is a necessary disturbance for the maintenance of some ecosystems, a range of anthropogenically deleterious consequences are associated with it, such as damage to assets and infrastructure, loss of life, as well as degradation to air quality leading to negative impacts on human health. Estimating carbon emissions from fire relies on a carbon mass balance technique which has evolved with two different interpretations in the fire emissions community. Databases reporting global fire emissions estimates use an approach based on `consumed biomass' which is an approximation to the biogeochemically correct `burnt carbon' approach. Disagreement between the two methods occurs because the `consumed biomass' accounting technique assumes that all burnt carbon is volatilized and emitted. By undertaking a global review of the fraction of burnt carbon emitted to the atmosphere, we show that the `consumed biomass' accounting approach overestimates global carbon emissions by 4.0%, or 100 Teragrams, annually. The required correction is significant and represents 9% of the net global forest carbon sink estimated annually. To correctly partition burnt carbon between that emitted to the atmosphere and that remaining as a post-fire residue requires the post-burn carbon content to be estimated, which is quite often not undertaken in atmospheric emissions studies. To broaden our understanding of ecosystem carbon fluxes, it is recommended that the change in carbon content associated with burnt residues be accounted for. Apart from correctly partitioning burnt carbon between the emitted and residue pools, it enables an accounting approach which can assess the efficacy of fire management operations targeted at sequestering carbon from fire. These findings are particularly relevant for the second commitment period for the Kyoto protocol, since improved landscape fire

  2. Study of the influence of carbon on the negative lead-acid battery electrodes

    NASA Astrophysics Data System (ADS)

    Bača, Petr; Micka, Karel; Křivík, Petr; Tonar, Karel; Tošer, Pavel

    Experiments were made with negative lead-acid battery electrodes doped with different concentrations of powdered carbon. It turned out that the rate of formation decreased with the rising concentration of carbon added into the active material. During accelerated cycling in the PSoC regime, the cycle life showed a maximum at a concentration of carbon near 1%, whereas at lower or higher concentrations the cycle life was profoundly lower. A marked increase of the active mass resistance with the cycle number was recorded at carbon concentrations above 2%. Orientation experiments showed that compression of the lead-acid laboratory cells caused an increase of the cycle life of the negative electrode in the studied regime.

  3. Removal of Lead (II) Ions from Aqueous Solutions onto Activated Carbon Derived from Waste Biomass

    PubMed Central

    Erdem, Murat; Ucar, Suat; Karagöz, Selhan; Tay, Turgay

    2013-01-01

    The removal of lead (II) ions from aqueous solutions was carried out using an activated carbon prepared from a waste biomass. The effects of various parameters such as pH, contact time, initial concentration of lead (II) ions, and temperature on the adsorption process were investigated. Energy Dispersive X-Ray Spectroscopy (EDS) analysis after adsorption reveals the accumulation of lead (II) ions onto activated carbon. The Langmuir and Freundlich isotherm models were applied to analyze equilibrium data. The maximum monolayer adsorption capacity of activated carbon was found to be 476.2 mg g−1. The kinetic data were evaluated and the pseudo-second-order equation provided the best correlation. Thermodynamic parameters suggest that the adsorption process is endothermic and spontaneous. PMID:23853528

  4. Removal of lead from aqueous effluents by adsorption on coconut shell carbon.

    PubMed

    Sekhar, M Chandra

    2008-04-01

    The application of adsorption for removal of heavy metals is quite popular and activated carbon is universally used as an adsorbent. However, high cost of its preparation and regeneration has led to a search for alternative sorbents, especially in the developing countries. A number of sorbents are used to remove metals by adsorption from industrial effluents, which include insoluble starch, xanthates, modified cotton and wool, tree barks, activated carbon, plant leaves and agricultural products. Therefore, as an alternative, coconut shell carbon (CSC), a low cost sorbent derived from organic waste material, was used in the present work, for removal of lead from aqueous effluents. The results of the batch sorption studies indicated that the efficiency of lead removal by coconut shell carbon is comparable to that of commercially available activated carbon. From the kinetic and equilibrium studies, the sorptive capacity of coconut shell carbon for lead was found to be 30 mg/g. Desorption and subsequent recovery of the metal from the surface of the sorbent was successfully demonstrated. Parameters affecting the sorption were evaluated.

  5. [Effect of lead and carbon monoxide under the condition of diabetic metabolism (author's transl)].

    PubMed

    Schlipköter, H W; Klitzke, M; Unnewehr, J

    1979-06-01

    The NZO-Mice were used to study the influence of carbon monoxide and lead under the condition of diabetic metabolism. The animals treated with 80 ppm (COHb 10.81) showed significantly lower tolerance for glucose. Even after removing the burden of carbon monoxide for 50 days, the blood sugar level after glucose tolerance test remained in experimental animals significantly higher than in controls (20-min-value). The NZO-Mice after enteral lead exposition showed no significant changes of the condition of the diabetic metabolism after the glucose tolerance test. However, the NZO-Mice, compared to NMRI mice and rats, reached significantly higher level of blood sugar.

  6. Prediction of oxidation performance of reinforced carbon-carbon material for Space Shuttle leading edges

    NASA Technical Reports Server (NTRS)

    Medford, J. E.

    1975-01-01

    A method was developed for predicting oxidation performance, in an earth atmospheric entry environment, of reinforced carbon-carbon material, coated for oxidation resistance. A model was developed which describes oxidation control mechanisms, and the equations defining these mechanisms were derived. These relations were used to correlate oxidation test data, and to infer pertinent rate constants. Predictions were made of material oxidation performance in a representative entry environment, and the predictions were compared with ground test data. Results indicate that the method can be successfully used for predicting material oxidation performance.

  7. Lead

    MedlinePlus

    ... are approximately half a million U.S. children ages 1-5 with blood lead levels above 5 micrograms per deciliter (µg/dL), the reference level at which CDC recommends public health actions be initiated. No safe blood lead level in children has been ...

  8. Electrochemistry of thin-plate lead-carbon batteries employing alternative current collectors

    NASA Astrophysics Data System (ADS)

    Lannelongue, Jérémy; Cugnet, Mikael; Guillet, Nicolas; Kirchev, Angel

    2017-06-01

    The article discusses the electrochemistry of lead-carbon battery cells based on thin-plate electrodes with alternative current collectors. The latter are comprised of lead-electroplated graphite foil and expanded titanium mesh coated with SnO2 replacing the conventional negative and positive grids. The results from charge/discharge tests, cycling voltammetry and impedance spectroscopy measurements show that the negative electrodes store energy via three types of electrochemical processes: electrostatic storage, reversible hydrogen storage and precipitation/dissolution of lead and lead sulfate. When the activated carbon is the predominant component of the negative active material the preferred energy storage mechanism is the reversible hydrogen storage. The use of titanium as alternative current collector allows to increase the active material to current collector ratio to 5: 1, retaining a high power performance and increasing the battery lifetime beyond 3000 equivalent cycles in partial state of charge cycling applications.

  9. Lead-carbon electrode designed for renewable energy storage with superior performance in partial state of charge operation

    NASA Astrophysics Data System (ADS)

    Zhang, Wen-Li; Yin, Jian; Lin, Zhe-Qi; Shi, Jun; Wang, Can; Liu, De-Bo; Wang, Yue; Bao, Jin-Peng; Lin, Hai-Bo

    2017-02-01

    Renewable energy storage is a key issue in our modern electricity-powered society. Lead acid batteries (LABs) are operated at partial state of charge in renewable energy storage system, which causes the sulfation and capacity fading of Pb electrode. Lead-carbon composite electrode is a good solution to the sulfation problem of LAB. In this paper, a rice-husk-derived hierarchically porous carbon with micrometer-sized large pores (denoted as RHC) has been used as the component of lead-carbon composite electrode. Scanning electron microscopy was used to characterize the morphology of lead-carbon composite electrode. Electrochemical impedance spectroscopy was used to determine the charge transfer capability of lead-carbon composite electrode. Both full charge-discharge method and charge-discharge method operating at harsh partial state of charge condition have been used to prove the superior energy storage capability of lead-carbon composite electrode. Experiment results prove that the micrometer-sized pores of RHC are beneficial to the construction and stability of lead-carbon composite electrode. Microporous carbon material with high surface area is not suitable for the construction of lead-carbon electrode due to the ruin of lead-carbon structure caused by severe electrochemical hydrogen evolution.

  10. Role of activated carbon fabric mask to prevent lead absorption--a short report.

    PubMed

    Kuruvilla, A; Pillay, V V; Adhikari, P; Venkatesh, T; Chakrapani, M; Krishnan, N G; Rajeev, A; Bastia, B K; Rao, H T J

    2008-10-01

    An attempt was made to study the usefulness of activated carbon fabric (ACF) mask to prevent lead absorption. Indigenous ACF masks were provided to eight workers involved in the manufacture of batteries. Their blood lead levels were determined before and after using these masks. There was a substantial decrease in blood lead level after using the mask among those who were under treatment for high blood lead levels. Three workers who were not under treatment for lead also showed a decrease in blood lead level, after using this ACF mask, suggesting the usefulness of ACF in preventing further exposure. Such a study has not been reported anywhere in the available literature and similar such studies with more number of masks is necessary to evaluate its effectiveness.

  11. Lead and copper removal from aqueous solutions using carbon foam derived from phenol resin.

    PubMed

    Lee, Chang-Gu; Jeon, Jun-Woo; Hwang, Min-Jin; Ahn, Kyu-Hong; Park, Chanhyuk; Choi, Jae-Woo; Lee, Sang-Hyup

    2015-07-01

    Phenolic resin-based carbon foam was prepared as an adsorbent for removing heavy metals from aqueous solutions. The surface of the produced carbon foam had a well-developed open cell structure and the specific surface area according to the BET model was 458.59m(2)g(-1). Batch experiments showed that removal ratio increased in the order of copper (19.83%), zinc (34.35%), cadmium (59.82%), and lead (73.99%) in mixed solutions with the same initial concentration (50mgL(-1)). The results indicated that the Sips isotherm model was the most suitable for describing the experimental data of lead and copper. The maximum adsorption capacity of lead and copper determined to Sips model were 491mgg(-1) and 247mgg(-1). The obtained pore diffusion coefficients for lead and copper were found to be 1.02×10(-6) and 2.42×10(-7)m(2)s(-1), respectively. Post-sorption characteristics indicated that surface precipitation was the primary mechanism of lead and copper removal by the carbon foam, while the functional groups on the surface of the foam did not affect metal adsorption.

  12. Carbon honeycomb grids for advanced lead-acid batteries. Part I: Proof of concept

    NASA Astrophysics Data System (ADS)

    Kirchev, Angel; Kircheva, Nina; Perrin, Marion

    2011-10-01

    The carbon honeycomb grid is proposed as innovative solution for high energy density lead acid battery. The proof of concept is demonstrated, developing grids suitable for the small capacity, scale of valve-regulated lead acid batteries with 2.5-3 Ah plates. The manufacturing of the grids, includes fast, known and simple processes which can be rescaled for mass production with a minimum, investment costs. The most critical process of green composite carbonisation by heating in inert, atmosphere from 200 to 1000 °C takes about 5 h, guaranteeing the low cost of the grids. An AGM-VRLA, cell with prototype positive plate based on the lead-2% tin electroplated carbon honeycomb grid and, conventional negative plates is cycled demonstrating 191 deep cycles. The impedance spectroscopy, measurements indicate the grid performance remains acceptable despite the evolution of the corrosion, processes during the cycling.

  13. [Adsorption kinetic and thermodynamic studies of lead onto activated carbons from cotton stalk].

    PubMed

    Li, Kun-quan; Zheng, Zheng; Jiang, Jian-chun; Zhang, Ji-biao

    2010-05-01

    Low-cost high surface area microporous carbons were prepared from cotton stalk and cotton stalk fiber by H3PO4 activation. The adsorption of lead ions on the carbons was investigated by conducting a series of batch adsorption experiments. The influence of solution pH value, contact time and temperature was investigated. The adsorption kinetics, thermodynamic behavior and mechanism were also discussed. The surface area and pore structure of the activated carbons were analyzed by BET equation, BJH method and H-K method according to the data from nitrogen adsorption at 77K. Boehm titration, Fourier transform infrared spectroscopy (FTIR), the point of zero charge (pH(PZC)) measurement and elemental analysis were used to characterize the surface properties. The results show that the carbons from cotton stalk and cotton stalk fiber have high surface area of 1570 and 1731 m2 x g(-1), and high content of oxygen-containing functional groups of 1.43 and 0.83 mmol x g(-1). The adsorption experiments show that the carbons have high adsorption capacity for lead, and the maximum adsorption equilibrium amount was found to be 120 mg x g(-1). The adsorption amount increased with contact time, and almost 80% of the adsorption occurred in the first 5 min. The pseudo-second-order model describes the adsorption kinetics most effectively. The Freundlich isotherm was found to the best explanation for experimental data. The negative change in free energy (delta G0) and positive change in enthalpy (delta H0) indicate that the adsorption is a spontaneous and endothermic process, and the adsorption of lead ions onto the carbons might be involved in an ion-exchange mechanism.

  14. Test and Analysis of a Hyper-X Carbon-Carbon Leading Edge Chine

    NASA Technical Reports Server (NTRS)

    Smith, Russell W.; Sikora, Joseph G.; Lindell, Michael C.

    2005-01-01

    During parts production for the X43A Mach 10 hypersonic vehicle nondestructive evaluation (NDE) of a leading edge chine detected on imbedded delamination near the lower surface of the part. An ultimate proof test was conducted to verify the ultimate strength of this leading edge chine part. The ultimate proof test setup used a pressure bladder design to impose a uniform distributed pressure field over the bi-planar surface of the chine test article. A detailed description of the chine test article and experimental test setup is presented. Analysis results from a linear status model of the test article are also presented and discussed. Post-test inspection of the specimen revealed no visible failures or areas of delamination.

  15. Pyrolysis of cellulose under ammonia leads to nitrogen-doped nanoporous carbon generated through methane formation.

    PubMed

    Luo, Wei; Wang, Bao; Heron, Christopher G; Allen, Marshall J; Morre, Jeff; Maier, Claudia S; Stickle, William F; Ji, Xiulei

    2014-01-01

    Here, we present a simple one-step fabrication methodology for nitrogen-doped (N-doped) nanoporous carbon membranes via annealing cellulose filter paper under NH3. We found that nitrogen doping (up to 10.3 at %) occurs during cellulose pyrolysis under NH3 at as low as 550 °C. At 700 °C or above, N-doped carbon further reacts with NH3, resulting in a large surface area (up to 1973.3 m(2)/g). We discovered that the doped nitrogen, in fact, plays an important role in the reaction, leading to carbon gasification. CH4 was experimentally detected by mass spectrometry as a product in the reaction between N-doped carbon and NH3. When compared to conventional activated carbon (1533.6 m(2)/g), the N-doped nanoporous carbon (1326.5 m(2)/g) exhibits more than double the unit area capacitance (90 vs 41 mF/m(2)).

  16. Ferroelectric triggering of carbon monoxide adsorption on lead zirco-titanate (001) surfaces

    NASA Astrophysics Data System (ADS)

    Tănase, Liviu Cristian; Apostol, Nicoleta Georgiana; Abramiuc, Laura Elena; Tache, Cristian Alexandru; Hrib, Luminița; Trupină, Lucian; Pintilie, Lucian; Teodorescu, Cristian Mihail

    2016-10-01

    Atomically clean lead zirco-titanate PbZr0.2Ti0.8O3 (001) layers exhibit a polarization oriented inwards P(‑), visible by a band bending of all core levels towards lower binding energies, whereas as introduced layers exhibit P(+) polarization under air or in ultrahigh vacuum. The magnitude of the inwards polarization decreases when the temperature is increased at 700 K. CO adsorption on P(‑) polarized surfaces saturates at about one quarter of a monolayer of carbon, and occurs in both molecular (oxidized) and dissociated (reduced) states of carbon, with a large majority of reduced state. The sticking of CO on the surface in ultrahigh vacuum is found to be directly related to the P(‑) polarization state of the surface. A simple electrostatic mechanism is proposed to explain these dissociation processes and the sticking of carbon on P(‑) polarized areas. Carbon desorbs also when the surface is irradiated with soft X-rays. Carbon desorption when the polarization is lost proceeds most probably in form of CO2. Upon carbon desorption cycles, the ferroelectric surface is depleted in oxygen and at some point reverses its polarization, owing to electrons provided by oxygen vacancies which are able to screen the depolarization field produced by positive fixed charges at the surface.

  17. Ferroelectric triggering of carbon monoxide adsorption on lead zirco-titanate (001) surfaces

    PubMed Central

    Tănase, Liviu Cristian; Apostol, Nicoleta Georgiana; Abramiuc, Laura Elena; Tache, Cristian Alexandru; Hrib, Luminița; Trupină, Lucian; Pintilie, Lucian; Teodorescu, Cristian Mihail

    2016-01-01

    Atomically clean lead zirco-titanate PbZr0.2Ti0.8O3 (001) layers exhibit a polarization oriented inwards P(−), visible by a band bending of all core levels towards lower binding energies, whereas as introduced layers exhibit P(+) polarization under air or in ultrahigh vacuum. The magnitude of the inwards polarization decreases when the temperature is increased at 700 K. CO adsorption on P(−) polarized surfaces saturates at about one quarter of a monolayer of carbon, and occurs in both molecular (oxidized) and dissociated (reduced) states of carbon, with a large majority of reduced state. The sticking of CO on the surface in ultrahigh vacuum is found to be directly related to the P(−) polarization state of the surface. A simple electrostatic mechanism is proposed to explain these dissociation processes and the sticking of carbon on P(−) polarized areas. Carbon desorbs also when the surface is irradiated with soft X-rays. Carbon desorption when the polarization is lost proceeds most probably in form of CO2. Upon carbon desorption cycles, the ferroelectric surface is depleted in oxygen and at some point reverses its polarization, owing to electrons provided by oxygen vacancies which are able to screen the depolarization field produced by positive fixed charges at the surface. PMID:27739461

  18. Ferroelectric triggering of carbon monoxide adsorption on lead zirco-titanate (001) surfaces.

    PubMed

    Tănase, Liviu Cristian; Apostol, Nicoleta Georgiana; Abramiuc, Laura Elena; Tache, Cristian Alexandru; Hrib, Luminița; Trupină, Lucian; Pintilie, Lucian; Teodorescu, Cristian Mihail

    2016-10-14

    Atomically clean lead zirco-titanate PbZr0.2Ti0.8O3 (001) layers exhibit a polarization oriented inwards P((-)), visible by a band bending of all core levels towards lower binding energies, whereas as introduced layers exhibit P((+)) polarization under air or in ultrahigh vacuum. The magnitude of the inwards polarization decreases when the temperature is increased at 700 K. CO adsorption on P((-)) polarized surfaces saturates at about one quarter of a monolayer of carbon, and occurs in both molecular (oxidized) and dissociated (reduced) states of carbon, with a large majority of reduced state. The sticking of CO on the surface in ultrahigh vacuum is found to be directly related to the P((-)) polarization state of the surface. A simple electrostatic mechanism is proposed to explain these dissociation processes and the sticking of carbon on P((-)) polarized areas. Carbon desorbs also when the surface is irradiated with soft X-rays. Carbon desorption when the polarization is lost proceeds most probably in form of CO2. Upon carbon desorption cycles, the ferroelectric surface is depleted in oxygen and at some point reverses its polarization, owing to electrons provided by oxygen vacancies which are able to screen the depolarization field produced by positive fixed charges at the surface.

  19. Carbon and lead isotope compositions of particulate matter in the atmosphere of Paris

    NASA Astrophysics Data System (ADS)

    Widory, D.; Roy, S.; Le Moullec, Y.; Goupil, G.

    2003-04-01

    The impact of the various sources of particulate matter in urban atmosphere is still subject to debate. This uncertainty cannot be lifted by the sole use of chemical parameters, and thus the need of complementary indexes may arise. In this study we show that the use of coupled carbon and lead isotopes not only allows a precise identification of the sources of PM10 in the atmosphere of Paris, but also permits the quantification of their respective contributions. The first step of the study consisted in the isotopic (C and Pb)characterisation of PM10 emitted by the main sources of pollution in the city (mainly road traffic and heating sources). Results show that carbon isotopes distinguish PM10 from diesel and natural gas from the other sources, while lead isotopes discriminates road traffic from industrial lead. Atmospheric PM10 samples were then taken and analysed for 2 sites in Paris, one located near the south-east of the city background pollution) and another on the ring (heavy road traffic influence). Results show that the pollution is quite homogeneous from one site to the other in terms of carbon and lead concentrations and isotope compositions. A clear distinction between the organic and inorganic phases of the particles is observed. While more than 90 % of the organic phase is originating from diesel traffic (more than 50 % of the car sold in France are using this type of fuel), lead isotopes show that the majority of the inorganic phase is produced by the industry. This duality clearly reflects both particle interactions and coagulation during their transport in the atmosphere, and the effect of the lead reduction policy in fuel during the last twenty years that resulted in a migration from a prevalent traffic origin towards a complete industrial contribution. This study paves the way to a wide area of research regarding the use of coupled stable and radiogenic isotope systematic in the field of air pollution.

  20. A novel leady oxide combined with porous carbon skeleton synthesized from lead citrate precursor recovered from spent lead-acid battery paste

    NASA Astrophysics Data System (ADS)

    Hu, Yuchen; Yang, Jiakuan; Zhang, Wei; Xie, Yanlin; Wang, Junxiong; Yuan, Xiqing; Vasant Kumar, R.; Liang, Sha; Hu, Jingping; Wu, Xu

    2016-02-01

    A novel nanostructured leady oxides comprising porous carbon skeleton has been synthesized by thermal decomposition of lead citrate precursor, recovered from spent lead-acid battery paste. The influences of O2 percentage in the calcination atmosphere (O2/N2 mixture) and the temperature on leady oxide product characteristics are studied by chemical analysis, scanning electron microscopy (SEM) and X-ray diffraction (XRD). The major crystalline phases of the products are identified as lead oxides, metallic Pb, and carbon. Porous carbon is observed as skeletons within the leady oxide (PbO containing some Pb metal) particles. Mass percentage of Pb metal in the leady oxide increases with increasing the proportion of oxygen in the calcination atmosphere. However, the amount of carbon decreases from approximately 8.0 to 0.3 wt%, and the porous carbon skeleton structure is gradually damaged with oxygen concentration increasing. A model about the thermal decomposition of lead citrate precursor is firstly proposed to elucidate these observations. The nanostructured leady oxides combined with porous carbon can be directly used as precursor of active materials in a new lead acid battery.

  1. Adsorption of diuron and dichlobenil on multiwalled carbon nanotubes as affected by lead.

    PubMed

    Chen, Guang-Cai; Shan, Xiao-Quan; Pei, Zhi-Guo; Wang, Huanhua; Zheng, Li-Rong; Zhang, Jing; Xie, Ya-Ning

    2011-04-15

    The effect of lead on the adsorption of diuron and dichlobenil on multiwalled carbon nanotubes (MWCNTs) was investigated to explore the possible application of MWCNTs for removal of both herbicides from contaminated water. The adsorption of diuron and dichlobenil on MWCNTs at pH 6 was nonlinear and fit the Polanyi-Manes model well. The adsorption of diuron and dichlobenil was closely correlated with specific surface areas and micropore volumes of MWCNTs. An increase in oxygen content of MWCNTs with same diameters and similar surface areas decreased the adsorption of diuron and dichlobenil, while increased the adsorption of lead. Micro-Fourier transform infrared spectroscopic study indicated that hydrogen bonding is a main mechanism responsible for the adsorption of diuron or dichlobenil onto MWCNTs-O. Oxygen containing groups, mainly carboxylic groups, significantly increased the adsorption of lead through the formations of outer-sphere and inner-sphere complexes, which are verified by X-ray absorption spectroscopic measurements. Oxygen containing groups and the presence of lead diminished the adsorption of diuron and dichlobenil. The suppression mechanisms of lead were ascribed to hydration and complexation of lead with carboxylic groups, which may occupy part of surface of MWCNTs-O. The large hydration shell of lead cations may intrude or shield hydrophobic and hydrophilic sites, resulting in a decreased adsorption of diuron and dichlobenil at the lead-complexed moieties. Copyright © 2011 Elsevier B.V. All rights reserved.

  2. Kinetics and equilibrium adsorption study of lead(II) onto activated carbon prepared from coconut shell.

    PubMed

    Sekar, M; Sakthi, V; Rengaraj, S

    2004-11-15

    Removal of lead from aqueous solutions by adsorption onto coconut-shell carbon was investigated. Batch adsorption experiments were performed to find out the effective lead removal at different metal ion concentrations. Adsorption of Pb2+ ion was strongly affected by pH. The coconut-shell carbon (CSC) exhibited the highest lead adsorption capacity at pH 4.5. Isotherms for the adsorption of lead on CSC were developed and the equilibrium data fitted well to the Langmuir, Freundlich, and Tempkin isotherm models. At pH 4.5, the maximum lead adsorption capacity of CSC estimated with the Langmuir model was 26.50 mg g(-1) adsorbent. Energy of activation (Ea) and thermodynamic parameters such as DeltaG, DeltaH, and DeltaS were evaluated by applying the Arrhenius and van't Hoff equations. The thermodynamics of Pb(II) on CSC indicates the spontaneous and endothermic nature of adsorption. Quantitative desorption of Pb(II) from CSC was found to be 75% which facilitates the sorption of metal by ion exchange.

  3. Characterisation of novel modified active carbons and marine algal biomass for the selective adsorption of lead.

    PubMed

    Malik, D J; Strelko, V; Streat, M; Puziy, A M

    2002-03-01

    This paper discusses the sorption performance of novel materials for the removal of lead(II) and copper(II) from near-neutral aqueous solutions. Active carbons with surface heteroatoms of oxygen and phosphorus have been prepared. The surface functional groups display weakly acidic ion exchange characteristics. The optimum solution pH for maximum metal sorption is related to the pK values of the surface functional groups. In oxygenated active carbons, pK values are not distinct but can be obtained by describing proton binding to the heterogeneous adsorbent surface as a continuous proton affinity distribution. Information derived from zeta-potential measurements combined with knowledge of the pK distribution function and concentration of surface functional groups has been used to explain the selectivity of oxidised active carbons towards lead(lI) in the presence of copper(II) from multi-metal bearing solutions. Marine algal-based biosorbents have been challenged with lead(II) and copper(II)-bearing wastewater. The weakly acidic carboxyl groups of structural polysaccharides present within the algal matrix display high sorption capacity for both metals. The negative surface charge of algal particles results in electrostatic interactions as well as coordination between metal species and the adsorbent surface. Proton affinity for the algal surface lowers the negative surface potential at pH values around 2. The surface functional groups in algae unlike those in oxidised active carbons may be represented by discrete acid-dissociation constant values. The influence of conformational differences in uronic-acid segments upon metal ion selectivity is discussed.

  4. Highly porous carbon from a natural cellulose fiber as high efficiency sorbent for lead in waste water.

    PubMed

    Ilangovan, Manikandan; Guna, Vijaykumar; Olivera, Sharon; Ravi, Ashwini; Muralidhara, H B; Santosh, M S; Reddy, Narendra

    2017-08-24

    The persistence of hollow centre in the carbon obtained from milkweed floss provides exceptional sorption characteristics, not seen in common biomasses or their derivatives. A considerably high sorption of 320mg of lead per gram of milkweed carbon was achieved without any chemical modification to the biomass. In this research, we have carbonized milkweed floss and used the carbon as a sorbent for lead in waste water. A high surface area of 170m(2)g(-1) and pore volume of 1.07cm(3)g(-1) was seen in the carbon. Almost complete removal (>99% efficiency) of lead could be achieved within 5min when the concentration of lead in the solution was 100ppm, close to that prevailing in industrial waste water. SEM images showed that the carbon was hollow and confocal images confirmed that the sorbate could penetrate inside the hollow tube. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. Geochemical partitioning of lead in biogenic carbonate sediments in a coral reef depositional environment.

    PubMed

    Horta-Puga, Guillermo

    2017-03-15

    The fate of trace elements in reef depositional environments has not been extensively investigated. The aim of this study was to determine the partitioning of Pb in sediments of the Veracruz Reef System, and its relation to local environmental sources. Lead was determined in four geochemical fractions: exchangeable (3.8±0.4μgg(-1)), carbonate (57.0±13.6μgg(-1)), organic matter (2.0±0.9μgg(-1)), and mineral (17.5±5.4μgg(-1)). For the mineral fraction, lead concentrations were higher in those reefs influenced by river discharge or by long-distance transport of terrigenous sediments. The bioavailable concentration of lead (range: 21.9-85.6μgg(-1)) indicates that the Veracruz Reef System is a moderately polluted area. As expected, the carbonate fraction contained the highest proportion of Pb (70%), and because the reef framework is largely made up of by biogenic carbonate sediments, hence, it is therefore the most important repository of Pb in coral reef depositional environments.

  6. Fracture Mechanics Analyses of Reinforced Carbon-Carbon Wing-Leading-Edge Panels

    NASA Technical Reports Server (NTRS)

    Raju, Ivatury S.; Phillips, Dawn R.; Knight, Norman F., Jr.; Song, Kyongchan

    2010-01-01

    Fracture mechanics analyses of subsurface defects within the joggle regions of the Space Shuttle wing-leading-edge RCC panels are performed. A 2D plane strain idealized joggle finite element model is developed to study the fracture behavior of the panels for three distinct loading conditions - lift-off and ascent, on-orbit, and entry. For lift-off and ascent, an estimated bounding aerodynamic pressure load is used for the analyses, while for on-orbit and entry, thermo-mechanical analyses are performed using the extreme cold and hot temperatures experienced by the panels. In addition, a best estimate for the material stress-free temperature is used in the thermo-mechanical analyses. In the finite element models, the substrate and coating are modeled separately as two distinct materials. Subsurface defects are introduced at the coating-substrate interface and within the substrate. The objective of the fracture mechanics analyses is to evaluate the defect driving forces, which are characterized by the strain energy release rates, and determine if defects can become unstable for each of the loading conditions.

  7. Single-Wall Carbon Nanotube Doping in Lead-Acid Batteries: A New Horizon.

    PubMed

    Banerjee, Anjan; Ziv, Baruch; Shilina, Yuliya; Levi, Elena; Luski, Shalom; Aurbach, Doron

    2017-02-01

    The addition of single-wall carbon nanotubes (SWCNT) to lead-acid battery electrodes is the most efficient suppresser of uncontrolled sulfation processes. Due to the cost of SWCNT, we studied the optimization loading of SWCNT in lead-acid battery electrodes. We optimized the SWCNT loading concentrations in both the positive and negative plates, separately. Loadings of 0.01% and 0.001% in the positive and negative active masses were studied, respectively. Two volts of lead-acid laboratory cells with sulfuric acid, containing silica gel-type electrolytes, were cycled in a 25% and 50% depth-of-discharge (DOD) cycling with a charging rate of C and 2C, respectively, and discharge rates of C/2 and C, respectively. All tests successfully demonstrated an excellent service life up to about 1700 and 1400 cycles for 25% and 50% DOD operations, respectively, at a low loading level of SWCNT. This performance was compared with CNT-free cells and cells with a multiwall carbon nanotube (MWCNT) additive. The outstanding performance of the lead-acid cells with the SWCNT additive is due to the oxidative stability of the positive plates during charging and the efficient reduction in sulfation in both plates while forming conducting active-material matrices.

  8. Removal of lead(II) from aqueous solutions using carbonate hydroxyapatite extracted from eggshell waste.

    PubMed

    Liao, Dexiang; Zheng, Wei; Li, Xiaoming; Yang, Qi; Yue, Xiu; Guo, Liang; Zeng, Guangming

    2010-05-15

    Carbonate hydroxyapatite (CHAP) synthesized from eggshell waste was used for removing lead ion from aqueous solutions. The effects of pH, contact time and initial concentration were studied in batch experiments. The maximum uptake of lead ion was obtained at pH 6.0. Adsorption equilibrium was established by 60 min. The pseudo-first order, pseudo-second order and intraparticle diffusion kinetic models were applied to study the kinetics of the sorption processes. The pseudo-second order kinetic model provided the best correlation (R(2)>0.9991) of the used experimental data compared to the pseudo-first order and intraparticle diffusion kinetic models. The adsorption of lead ion by CHAP increased as the initial concentration of lead ion increased in the medium. The maximum lead ion adsorbed was found to be 101 mg g(-1). It was found that the adsorption of Pb(II) on CHAP was correlated well (R(2)=0.9995) with the Langmuir equation as compared to Freundlich isotherm equation under the concentration range studied. This study indicated that CHAP could be used as an efficient adsorbent for removal of lead ion from aqueous solution.

  9. Potentiometric carbon paste sensors for lead(II) based on dithiodibenzoic and mercaptobenzoic acids.

    PubMed

    Gismera, María Jesús; Sevilla, María Teresa; Procopio, Jesús R

    2006-03-01

    Dithiodibenzoic (DTB) acid and mercaptobenzoic (MB) acid were studied to characterize their abilities as modifier agents for lead(II) sensors. For both sensors, the best results were obtained with modified carbon paste electrodes with 24.1% of ligand. The pH influence on the potentiometric response was studied. The selectivity coefficients for both modified electrodes were tabulated. A potentiometric sensor based on DTB acid exhibited a more sensitive and selective response to lead ions than an MB electrode. The limits of detection for the DTB and MB electrodes were very similar, 5.01 x 10(-8) M and 3.98 x 10(-8) M, respectively, for lead(II) activity. The DTB sensor was applied to lead(II) ion determination in real samples and as an indicator electrode in potentiometric titrations. Natural and commercial humic acids were titrated using the DTB electrode to estimate the stability constant between these organic compounds and the lead(II) ions with successful results.

  10. Influence of carbons on the structure of the negative active material of lead-acid batteries and on battery performance

    NASA Astrophysics Data System (ADS)

    Pavlov, D.; Nikolov, P.; Rogachev, T.

    It has been established that addition of carbon additives to the lead negative active material (NAM) of lead-acid batteries increase battery charge acceptance in hybrid electric vehicle mode of operation. The present work studies three types of activated carbons and two types of carbon blacks with the aim to evaluate their efficiency in improving the charge acceptance of lead-acid batteries. It has been established that the size of carbon particles and their affinity to lead are essential. If carbon particles are of nanosizes, they are incorporated into the bulk of the skeleton branches of NAM and may thus increase the latter's ohmic resistance. Their content in NAM should not exceed 0.2-0.5 wt.%. At this loading level, carbon grains are adsorbed only on the surface of NAM contributing to the increase of its specific surface area and thus improving its charge acceptance. When carbon particles are of micron sizes and have high affinity to lead, they are integrated into the skeleton structure of NAM as a structural component and act as super-capacitors, i.e. electric charges are concentrated in them and then the current is distributed along the adjacent branches of the lead skeleton with the lowest ohmic resistance. This eventually improves the charge acceptance of the negative battery plates.

  11. The ionic strength dependence of lead (II) carbonate complexation in perchlorate media

    NASA Astrophysics Data System (ADS)

    Easley, Regina A.; Byrne, Robert H.

    2011-10-01

    Lead speciation in many aqueous geochemical systems is dominated by carbonate complexation. However, direct observations of Pb complexation by carbonate ions are few in number. This work represents the first investigation of the equilibrium Pb+CO32-⇌PbCO30 over a range of ionic strength. Through spectrophotometric observations of PbCO30 formation at 25 °C in NaHCO 3-NaClO 4 solutions, PbCO30 formation constants of the form COβ1=[PbCO30]/[Pb][CO32-] were determined between 0.001 and 5.0 molal ionic strength. Formation constant results were well represented by the equation: logCO3β1=(6.789±0.022)-{4.088·I0.5}/{1+1.5I0.5}+(0.244±0.012)I . This result, combined with previous critical assessments of formation constants for the equilibrium PbCO30+CO32-⇌Pb(CO)22-, was used to estimate the ionic strength dependence for the equilibrium Pb+2CO32-⇌Pb(CO)22-: logCO3β2=(10.41±0.18)-{4.088·I0.5}/{1+1.5I0.5}-(0.31±0.33)I where COβ2=[Pb(CO)22-]/[Pb][CO32-]2. The carbonate complexation constants produced in this study, combined with previous complexation constants for formation of Pb chloride and hydroxide species, were used to predict formation constants for mixed-ligand species Pb(CO)Cl, Pb(OH)Cl, and Pb(CO)OH. Formation constant estimates for the system Pb-HCO3-Cl-H were then used to assess Pb speciation in seawater. In the absence of complexation by organics, approximately 1.9% of the total lead in surface seawater ( S = 35, t = 25 °C, pH ˜8.2 (free H concentration scale)) is present as free hydrated Pb. Carbonate complexes, PbCO30 and Pb(CO)Cl, are predominant forms of Pb in seawater at high pH, and lead chloride complexes are predominant species at low pH. For pH >7.7 the sum concentration of PbCO30, Pb(CO)Cl, PbOH, and Pb(OH)Cl in seawater exceeds the sum concentration of Pb, PbCl, PbCl20, and PbCl3-.

  12. Sn-Pb and lead free solders containing active carbon particles

    NASA Astrophysics Data System (ADS)

    Talas, S.; Gökçe, B.; Çakmakkaya, M.

    2016-08-01

    Upon the legislations issued by the governmental agencies, many companies are in effort of using lead free solders for their electronic products. Many researchers have also focused on lead free solders and determined their physical properties to the merit of their desired strength and conductivity which turns out to be a potentially advantageous after all. The addition of nano particles into the solder alloys has been attempted to investigate the property change caused by such addition from which a main outcome was a limited improved mechanical and physical properties such as lowering the melting temperature. In this study, the addition of nano active carbon particles to Pb-Sn and Pb-free solder alloys were made and characterization studies were conducted to determine their basic properties such as electrical conductivity, microstructural study and also phase transformations. The results indicate that the addition of active carbon particles brings about a change in thermal properties more markedly than other properties with respect to the amount of addition.

  13. Capacitive carbon and electrochemical lead electrode systems at the negative plates of lead-acid batteries and elementary processes on cycling

    NASA Astrophysics Data System (ADS)

    Pavlov, D.; Nikolov, P.

    2013-11-01

    Batteries in hybrid electric vehicles operate in High-Rate Partial-State-of-Charge (HRPSoC) cycling duty. To make lead-acid batteries suitable for this duty, carbon is added to the negative active material. As a result of this technological change, two electrical systems form at the negative plates: (a) a capacitive carbon system comprising high-rate charging and discharging of the electric double layer; low Ah capacity, and (b) a lead electrochemical system, comprising oxidation of Pb to PbSO4 during discharge and vice versa during charge; this system is slow to accept charge, but has high Ah capacity. Through cycling lead-acid cells under HRPSoC conditions with short current pulses of various durations we have established that the processes involved in the capacitive system proceed highly reversibly and complete hundreds of thousands HRPSoC cycles. The number of cycles achieved by the electrochemical system is limited to tens of thousands and lead to progressive sulfation. Carbon added to the negative active material changes the latter's structure. The specific surface of NAM increases and the median pore radius decreases. Some carbon additives may reduce the radius of the pores in NAM to membrane sizes, which may change the chemistry of the electrochemical system.

  14. Evaluation of lead/carbon devices for utility applications : a study for the DOE Energy Storage Program.

    SciTech Connect

    Walmet, Paula S.

    2009-06-01

    This report describes the results of a three-phase project that evaluated lead-based energy storage technologies for utility-scale applications and developed carbon materials to improve the performance of lead-based energy storage technologies. In Phase I, lead/carbon asymmetric capacitors were compared to other technologies that used the same or similar materials. At the end of Phase I (in 2005) it was found that lead/carbon asymmetric capacitors were not yet fully developed and optimized (cost/performance) to be a viable option for utility-scale applications. It was, however, determined that adding carbon to the negative electrode of a standard lead-acid battery showed promise for performance improvements that could be beneficial for use in utility-scale applications. In Phase II various carbon types were developed and evaluated in lead-acid batteries. Overall it was found that mesoporous activated carbon at low loadings and graphite at high loadings gave the best cycle performance in shallow PSoC cycling. Phase III studied cost/performance benefits for a specific utility application (frequency regulation) and the full details of this analysis are included as an appendix to this report.

  15. Adsorption of divalent lead ions by zeolites and activated carbon: effects of pH, temperature, and ionic strength.

    PubMed

    Payne, Kelly B; Abdel-Fattah, Tarek M

    2004-01-01

    Lead alloy bullets used at the 2600 military small arm ranges and 9000 nonmilitary outdoor shooting ranges in the United States are a source of mobilized lead ions under conditions of low pH, significant changes in ionic strength, changes in the reduction oxidation potential (redox), and through binding metal ions to soil organic matter. Once mobile, these lead ions can contaminate adjacent soil and water. Batch adsorption kinetic and isotherm studies were conducted to compare and evaluate different types of adsorbents for lead ion removal from aqueous media. The effects on lead ion absorption from pH changes, competing ions, and temperature increases were also investigated. Adsorbent materials such as activated carbon and naturally occurring zeolites (clinoptilolite and chabazite) were selected because of their relative low cost and because the zeolites are potential point-of-use materials for mitigating wastewater runoff. Molecular sieves, Faujasite (13X) and Linde type A (5A) were selected because they provide a basis for comparison with previous studies and represent well-characterized materials. The relative rate for lead ion adsorption was: 13X > chabazite > clinoptilolite > 5A > activated carbon. Modeling lead ion adsorption by these adsorbents using the Langmuir and Freundlich isotherm expressions determined the adsorbents' capacity for lead ion removal from aqueous media. 13X, 5A, and activated carbon best fit the Langmuir isotherm expression; chabazite and clinoptilolite best fit the Freundlich isotherm. Applications of chabazite would require pH values between 4 and 11, clinoptilolite between 3 and 11, while activated carbon would operate at a pH above 7. Ionic competition reduced lead ion removal by the zeolites, but enhanced activated carbon performance. Increasing temperature improved adsorption performance for the zeolites; activated carbon lead ion adsorption was temperature independent.

  16. Experimental determination of lead carbonate solubility at high ionic strengths: A Pitzer model description

    DOE PAGES

    Xiong, Yongliang

    2015-05-06

    In this article, solubility measurements of lead carbonate, PbCO3(cr), cerussite, as a function of total ionic strengths are conducted in the mixtures of NaCl and NaHCO3 up to I = 1.2 mol•kg–1 and in the mixtures of NaHCO3 and Na2CO3 up to I = 5.2 mol•kg–1, at room temperature (22.5 ± 0.5 °C). The solubility constant (log Ksp) for cerussite, PbCO3(cr) = Pb2+ + CO32- was determined as –13.76 ± 0.15 (2σ) with a set of Pitzer parameters describing the specific interactions of PbCO3(aq), Pb(CO3)22-, and Pb(CO3)Cl– with the bulk-supporting electrolytes, based on the Pitzer model. The model developed inmore » this work can reproduce the experimental results including model-independent solubility values from the literature over a wide range of ionic strengths with satisfactory accuracy. The model is expected to find applications in numerous fields, including the accurate description of chemical behavior of lead in geological repositories, the modeling of formation of oxidized Pb–Zn ore deposits, and the environmental remediation of lead contamination.« less

  17. Lead isotopic composition of paleozoic and late proterozoic marine carbonate rocks in the vicinity of Yucca Mountain, Nevada

    USGS Publications Warehouse

    Zartman, Robert E.; Kwak, Loretta M.

    1993-01-01

    Paleozoic and Late Proterozoic marine carbonate rocks (limestones, dolomites, and their metamorphic equivalents) cropping out in the vicinity of Yucca Mountain contain lead with an isotopic composition strongly suggesting them to be a major source of the lead observed at Trench 14 in the carbonate phase of carbonate-silica veins and nearby surficial calcrete deposits. Six whole-rock samples of marine carbonate rocks yield 206Pb/204Pb = 19.21-29.06, 207Pb/204Pb = 15.74-16.01, and 208Pb/204Pb = 37.90-39.25, and leachate and residue fractions of the rocks reveal additional isotopic heterogeneity within individual samples. Two samples of eolian dust also have isotopic compositions lying along a 'carbonate' to 'silicate' mixing trend that appears to arise entirely from pedogenic processes. The tendency for the marine carbonate rocks to evolve highly uranogenic, but no thorogenic, lead results in a distinctive isotopic composition that serves as a tracer in eolian dust and secondary carbonate minerals derived from the marine carbonate rocks.

  18. 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.

  19. Carbon nanotubes as an efficient hole collector for high voltage methylammonium lead bromide perovskite solar cells.

    PubMed

    Li, Zhen; Boix, Pablo P; Xing, Guichuan; Fu, Kunwu; Kulkarni, Sneha A; Batabyal, Sudip K; Xu, Wenjing; Cao, Anyuan; Sum, Tze Chien; Mathews, Nripan; Wong, Lydia Helena

    2016-03-28

    A high open circuit voltage (V(OC)) close to 1.4 V under AM 1.5, 100 mW cm(-2) conditions is achieved when carbon nanotubes (CNTs) are used as a hole conductor in methyl ammonium lead bromide (MAPbBr3) perovskite solar cells. Time-resolved photoluminescence and impedance spectroscopy investigations suggest that the observed high V(OC) is a result of the better charge extraction and lower recombination of the CNT hole conductor. Tandem solar cells with all perovskite absorbers are demonstrated with a MAPbBr3/CNT top cell and a MAPbI3 bottom cell, achieving a V(OC) of 2.24 V in series connection. The semitransparent and high voltage MAPbBr3/CNT solar cells show great potential for applications in solar cell windows, tandem solar cells and solar driven water splitting.

  20. Carbon honeycomb grids for advanced lead-acid batteries. Part II: Operation of the negative plates

    NASA Astrophysics Data System (ADS)

    Kirchev, A.; Dumenil, S.; Alias, M.; Christin, R.; de Mascarel, A.; Perrin, M.

    2015-04-01

    The article presents the recent progress in the carbon honeycomb grid technology for valve-regulated lead-acid batteries with absorptive glass-mat separators (AGM-VRLAB). The work is focused on the development of negative current collectors using industrial grade composite honeycomb precursors. The developed model AGM-VRLA cells comprised of one prototype honeycomb negative electrode and two conventional traction positive counter-electrodes show high utilisation of the negative active material and long cycle life both in high-rate partial state of charge (HRPSoC) cycling mode and in deep cycling mode. The analysis of the results from the cycle-life tests and the tear-down analysis indicate that the benefits delivered by the novel grids can be related to the low mesh size of the grid, low γ-coefficient, as well as the use of milled carbon fibre additive. The combination of the three, results in the reversibility of the negative active material sulfation process when the electrolyte concentration in the cells is lower than the one traditionally used in the AGM-VRLAB technology. The negative plates show no signs of irreversible degradation after more than 900 cycles in deep cycling mode and more than 2000 capacity turnovers (equivalent cycles) in HRPSoC cycling mode.

  1. ACCIDENTAL DROP OF A CARBON STEEL/LEAD SHIPPING CASK AT LOW TEMPERATURES

    SciTech Connect

    B. D. Hawkes; K. R. Durstine

    2007-07-01

    A shielded cask is used to transport radioactive materials between facilities. The cask was fabricated with an outer and inner shell of hot rolled low carbon steel. Lead was poured in the annular space between the shells to provide radiation shielding. Carbon steel is known to be susceptible to lowtemperature brittle fracture under impact loading. This paper will present the analysis results representing postulated transportation accidents during on-site transfers of the cask. The accident scenarios were based on a series of cask drops onto a rigid surface from a height of 6 ft assuming brittle failure of the cask shell at subzero temperatures. Finite element models of the cask and its contents were solved and post processed using ABAQUS software. Each model was examined for failure to contain radioactive materials and/or significant loss of radiation shielding. Results of these analyses show that the body of the cask exhibits considerable ruggedness and will remain largely intact after the impact. There will be deformation of the main cask body with localized brittle failure of the cask outer shell and components and but no complete penetration of the cask shielding. The cask payload outer waste can will experience some permanent plastic deformation in each drop, but will not be deformed to the point where it will rupture, thus maintaining confinement of the can contents.

  2. Adsorption of Lead ions onto Activated Carbon derived from Sugarcane bagasse

    NASA Astrophysics Data System (ADS)

    Salihi, I. U.; Kutty, S. R. M.; Isa, M. H.

    2017-05-01

    In this study, activated carbon was developed from sugarcane bagasse and its effectiveness in adsorbing lead (Pb2+) ions from synthetic aqueous solution was examined. Sugarcane bagasse activated carbon (SCBA) was developed in a tube furnace at a temperature of 900 °C, a heating rate of 10 °C/min, residence time of 3 hours, and at a nitrogen flow rate of 100 mL/min. Batch adsorption experiments were carried out to investigate the effects of pH and SCBA dosages on the adsorption process. The batch adsorption test showed that extent of Pb2+ adsorption by SCBA was dependent upon pH and SCBA dosage. The optimum pH for Pb2+ adsorption was found to be at pH 5.0. Maximum Pb2+ removal efficiency obtained from the batch studies was 87.3 % at SCBA dosage of 10 g/L. Equilibrium adsorption data was described by Langmuir model with a coefficient of determination (R2) of 0.9508. Maximum adsorption capacity according to Langmuir model was evaluated to be 23.4 mg/g. The adsorption capacity of the SCBA was compared with that of other plant-based adsorbents. SCBA is an effective adsorbent for the removal of Pb2+ from aqueous solution.

  3. Accidental Drop of a Carbon Steel/Lead Shipping Cask (HFEF 14) at Low Temperatures

    SciTech Connect

    Brian D. Hawkes; Michael E. Nitzel

    2007-08-01

    A shielded cask is used to transport radioactive materials between facilities at the Idaho National Laboratory. The cask was fabricated with an outer and inner shell of A36 carbon steel with lead poured in the annular space between the shells to provide radiation shielding. Carbon steel is known to be susceptible to low-temperature brittle fracture under impact loading. This paper will present the analysis results representing postulated transportation accidents during on-site transfers of the cask at subzero temperatures. The accident scenarios were based on a series of cask drops onto a rigid surface from a height of 1.83m (6 ft.) Finite element models of the cask and its contents were solved and post processed using the ABAQUS software. Each model was examined for failure to contain radioactive materials and/or significant loss of radiation shielding. Results of these analyses show that the body of the cask exhibits considerable ruggedness and will remain largely intact after the impact. There will be deformation of the main cask body with localized brittle failure of the cask outer shell and door structure. The cask payload outer waste can remains in the cask but will experience some permanent plastic deformation in each drop. It will not be deformed to the point where it will rupture, thus maintaining confinement of the can contents.

  4. Detection of lead ions in picomolar concentration range using underpotential deposition on silver nanoparticles-deposited glassy carbon electrodes.

    PubMed

    Sivasubramanian, R; Sangaranarayanan, M V

    2011-09-30

    The efficacy of silver-deposited glassy carbon electrode for the determination of lead ions at the sub-nanomolar concentration ranges is investigated. The silver nanoparticles are electrodeposited on glassy carbon electrode using chronoamperometry and the electrode surface is characterized using SEM. Lead ions are detected in the region of underpotential deposition. The analysis is performed in square wave mode in the stripping voltammetry without the removal of oxygen. The detection limit of 10 pM has been obtained with a constant potential of -0.7 V during the electrodeposition step for a period of 50s. The interference of surfactants in the detection of lead ions is also studied.

  5. Characterization of Sodium Carbonate (Na2CO3) Treated Rice Husk Activated Carbon and Adsorption of Lead from Car Battery Wastewater

    NASA Astrophysics Data System (ADS)

    Hanum, F.; Bani, O.; Izdiharo, A. M.

    2017-03-01

    The use of rice husk as adsorbent would not only reduce its disposal problems, but would also produce value-added products, such as activated carbon derived from rice husk. This study aimed to determine the optimum carbonization temperature for activated carbon production from rice husk and its adsorption performance on Pb in car battery wastewater. In this study, activated carbon was produced by carbonizing rice husk 400-600 °C for 90-150 minutes followed by chemical activation using 5% Na2CO3 and sieving to 100 meshes. Lead adsorption was measured using atomic absorption spectroscopy (AAS). Results suggested that highest carbon yield of 47.75% was obtained for carbonization at 500 °C for 150 minutes. At that condition, produced activated carbon contained 3.35% moisture, 30.86% ash, 18.04% volatile matter. The adsorption capacity was found to be 0.6007 mg lead/g adsorbent with % adsorpsi 58.08%

  6. Experimental determination of lead carbonate solubility at high ionic strengths: A Pitzer model description

    SciTech Connect

    Xiong, Yongliang

    2015-05-06

    In this article, solubility measurements of lead carbonate, PbCO3(cr), cerussite, as a function of total ionic strengths are conducted in the mixtures of NaCl and NaHCO3 up to I = 1.2 mol•kg–1 and in the mixtures of NaHCO3 and Na2CO3 up to I = 5.2 mol•kg–1, at room temperature (22.5 ± 0.5 °C). The solubility constant (log Ksp) for cerussite, PbCO3(cr) = Pb2+ + CO32- was determined as –13.76 ± 0.15 (2σ) with a set of Pitzer parameters describing the specific interactions of PbCO3(aq), Pb(CO3)22-, and Pb(CO3)Cl with the bulk-supporting electrolytes, based on the Pitzer model. The model developed in this work can reproduce the experimental results including model-independent solubility values from the literature over a wide range of ionic strengths with satisfactory accuracy. The model is expected to find applications in numerous fields, including the accurate description of chemical behavior of lead in geological repositories, the modeling of formation of oxidized Pb–Zn ore deposits, and the environmental remediation of lead contamination.

  7. Electrochemical determination of cadmium and lead on pristine single-walled carbon nanotube electrodes.

    PubMed

    Bui, Minh-Phuong Ngoc; Li, Cheng Ai; Han, Kwi Nam; Pham, Xuan-Hung; Seong, Gi Hun

    2012-01-01

    A flexible, transparent, single-walled carbon nanotube (SWCNT) film electrode was prepared by vacuum filtering methods, followed by photolithographic patterning of a photoresist polymer on the SWCNT surface. The morphology of the SWCNT film electrode surface was characterized using a field-emission scanning electron microscope coupled to an energy-dispersive X-ray spectrophotometer. The electrodes were successfully used as a mercury-free electrochemical sensor for individual and simultaneous detection of cadmium (Cd(2+)) and lead (Pb(2+)) in 0.02 M HCl by square-wave stripping voltammetry. Some important operational parameters, including deposition time, deposition potential, square-wave amplitude, and square wave-frequency were optimized for the detection of Cd(2+) and Pb(2+). The newly developed sensor showed good linear behavior in the examined concentration. For individual Cd(2+) and Pb(2+) ion detection, the linear range was found from 0.033 to 0.228 ppm with detection limits of 0.7 ppb (R(2) = 0.985) for Cd(2+) and 0.8 ppb (R(2) = 0.999) for Pb(2+). For simultaneous detection, the linear range was found from 0.033 to 0.280 ppm with a limit of detection of 2.2 ppb (R(2) = 0.976) and 0.6 ppb (R(2) = 0.996) for Cd(2+) and Pb(2+), respectively. SWCNT film electrodes offered favorable reproducibility of ± 5.4% and 4.3% for Cd(2+) and Pb(2+), respectively. The experiments demonstrated the applicability of carbon nanotubes, specifically in the preparation of SWCNT films. The results suggest that the proposed flexible SWCNT film electrodes can be applied as simple, efficient, cost-effective, and/or disposable electrodes for simultaneous detection of heavy metal ions.

  8. Electrochemiluminescence of graphitic carbon nitride and its application in ultrasensitive detection of lead(II) ions.

    PubMed

    Zhang, Yan; Zhang, Lina; Kong, Qingkun; Ge, Shenguang; Yan, Mei; Yu, Jinghua

    2016-10-01

    Graphitic carbon nitride (g-C3N4) materials with a layered structure have unusual physicochemical properties. Herein it was shown that g-C3N4 quantum dots (QDs) obtained through a thermal-chemical etching route exhibited attractive upconversion and electrochemiluminescence (ECL) properties. After modification on nanoporous gold (NPG) with a sponge-like porous structure, g-C3N4 QDs were employed to fabricate an ECL sensor for the determination of Pb(2+) using target - dependent DNAzyme as the recognition unit. Moreover, magnetic reduced graphene oxide nanosheets (rGO) attached with Fe3O4 nanoparticles (rGO-Fe3O4) were obtained via a one-pot in situ reduction approach, and used as carriers of DNAzyme. To make full use of the unique magnetic property the prepared rGO-Fe3O4, a flow injection ECL detecting cell was designed using indium tin oxide (ITO) glass as working electrode. Due to the unique separation and enrichment properties of magnetic Fe3O4-rGO materials as well as wire-like conductivity of NPG, high sensitivity and selectivity for the determination of Pb(2+) in real water samples were achieved. This indicates that g-C3N4 has excellent anodic ECL performance in the presence of triethanolamine, and could be applied in real environmental samples analyses. Graphical Abstract Graphitic carbon nitride based electrochemiluminescence sensor for the sensitive monitor of lead(II) ions in real samples was constructed.

  9. Partial carbonized nanoporous resin for uptake of lead from aqueous solution.

    PubMed

    Ghiloufi, I; Al-Hobaib, A S; El Mir, L

    2015-01-01

    Four partial carbonized nanoporous resins (PCNRs), based on organic xerogel compounds, were synthesised by the sol-gel method from pyrogallol and formaldehyde mixtures in water using picric acid as catalyst. The PCNRs were prepared at different pyrolysis temperatures: T(1) = 200 °C (PF-200), T(2) = 300 °C (PF-300), T(3) = 400 °C (PF-400), or T(4) = 500 °C (PF-500). The PCNRs were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Fourier transformed infrared spectroscopy, and nitrogen porosimetry. The obtained results show that PF-200 is more efficient for the removal of Pb(2+) from aqueous solution than the other adsorbent prepared in this study. The characteristics of lead uptake by PF-200 were explored using well-established and effective parameters including pH, contact time, initial metal ion concentration and temperature. Optimum adsorption of Pb(2+), using PF-200, was observed at pH 4.5. The Langmuir model gave a better fit than the other models, and kinetic studies revealed that the adsorption was well fitted by the pseudo second-order kinetic model and thermodynamic properties, i.e., Gibbs free energy change, enthalpy change and entropy change, showed that adsorption of Pb(2+) onto PF-200 was endothermic, spontaneous and feasible in the temperature range of 298-328 K.

  10. Does iron fertilization lead to rapid carbon export in the Southern Ocean?

    NASA Astrophysics Data System (ADS)

    Charette, Matthew A.; Buesseler, Ken O.

    2000-10-01

    The Southern Ocean has the potential to influence climate due to its large inventory of excess macronutrients such as nitrate and phosphate. It has been hypothesized that if the supply of the micronutrient iron increased, it would lead to enhanced uptake of atmospheric CO2 and hence the sequestration of carbon via sinking particles [Martin, 1990]. While much has been learned about iron limitation and low phytoplankton biomass in high-nutrient, low-chlorophyll regions [Martin, 1991; Coale et al., 1996], less is known about the effect of Fe on particle export. Here we present results from the first detailed study of particle export during a mesoscale iron fertilization experiment (the Southern Ocean Iron Release Experiment (SOIREE)). Measurements of the natural tracer thorium-234 indicate negligible particle export within 14 days after the initial infusion of iron. We attribute this lack of response to colder water temperatures that promote slower cell metabolism in phytoplankton and hence slower secondary responses of herbivores and particle aggregation.

  11. Dipole Alignment at the Carbon Nanotube and Methyl Ammonium Lead Iodide Perovskite Interface

    SciTech Connect

    Przepioski, Joshua

    2015-08-28

    This work correlates resonant peaks from first principles calculation on ammonia (NH3) Nitrogen 1s x-ray absorption spectroscopy (XAS) within the methyl ammonium lead iodide perovskite (CH3NH3PbI3), and proposes a curve to determine the alignment of the methyl ammonium dipole if there exists angular dependence. The Nitrogen 1s XAS was performed at varying incident angles on the perovskite with and without a carbon nanotube (CNT) interface produced from an ultrasonic spray deposition. We investigated the peak contribution from PbI2 and the poly(9,9-dioctylfluorene- 2,7-diyl) with bipyridine (PFO-BPy) wrapped around the CNT, and used normalization techniques to better identify the dipole alignment. There was angular dependence on samples containing the CNT interface suggesting an existing dipole alignment, but there was no angular dependence on the perovskite samples alone; however, more normalization techniques and experimental work must be performed in order to ensure its validity and to better describe its alignment, and possible controlling factors.

  12. Dipole Alignment at the Carbon Nanotube and Methyl Ammonium Lead Trihalide Perovskite Interface - Oral Presentation

    SciTech Connect

    Przepioski, Joshua

    2015-08-25

    This work correlates resonant peaks from first principles calculation on ammonia (NH3) Nitrogen 1s x-ray absorption spectroscopy (XAS) within the methyl ammonium lead iodide perovskite (CH3NH3PbI3), and proposes a curve to determine the alignment of the methyl ammonium dipole if there exists angular dependence. The Nitrogen 1s XAS was performed at varying incident angles on the perovskite with and without a carbon nanotube (CNT) interface produced from an ultrasonic spray deposition. We investigated the peak contribution from PbI2 and the poly(9,9-dioctylfluorene-2,7-diyl) with bipyridine (PFO-BPy) wrapped around the CNT, and used normalization techniques to better identify the dipole alignment. There was angular dependence on samples containing the CNT interface suggesting an existing dipole alignment, but there was no angular dependence on the perovskite samples alone; however, more normalization techniques and experimental work must be performed in order to ensure its validity and to better describe its alignment, and possible controlling factors.

  13. Woody plant encroachment into grasslands leads to accelerated erosion of previously stable organic carbon from dryland soils

    NASA Astrophysics Data System (ADS)

    Puttock, Alan; Dungait, Jennifer A. J.; Macleod, Christopher J. A.; Bol, Roland; Brazier, Richard E.

    2014-12-01

    Drylands worldwide are experiencing rapid and extensive environmental change, concomitant with the encroachment of woody vegetation into grasslands. Woody encroachment leads to changes in both the structure and function of dryland ecosystems and has been shown to result in accelerated soil erosion and loss of soil nutrients. Covering 40% of the terrestrial land surface, dryland environments are of global importance, both as a habitat and a soil carbon store. Relationships between environmental change, soil erosion, and the carbon cycle are uncertain. There is a clear need to further our understanding of dryland vegetation change and impacts on carbon dynamics. Here two grass-to-woody ecotones that occur across large areas of the southwestern United States are investigated. This study takes a multidisciplinary approach, combining ecohydrological monitoring of structure and function and a dual-proxy biogeochemical tracing approach using the unique natural biochemical signatures of the vegetation. Results show that following woody encroachment, not only do these drylands lose significantly more soil and organic carbon via erosion but that this includes significant amounts of legacy organic carbon which would previously have been stable under grass cover. Results suggest that these dryland soils may not act as a stable organic carbon pool, following encroachment and that accelerated erosion of carbon, driven by vegetation change, has important implications for carbon dynamics.

  14. Carbon dioxide effects research and assessment program: flux of organic carbon by rivers to the oceans. [Lead abstract

    SciTech Connect

    1981-04-01

    Separate abstracts were prepared for the 15 papers presented in this workshop report. The state of knowledge about the role of rivers in the transport, storage and oxidation of carbon is the subject of this report. (KRM)

  15. Followup to Columbia Investigation: Reinforced Carbon/Carbon From the Breach Location in the Wing Leading Edge Studied

    NASA Technical Reports Server (NTRS)

    Jacobson, Nathan S.; Opila, Elizabeth J.; Tallant, David

    2005-01-01

    Initial estimates on the temperature and conditions of the breach in the Space Shuttle Columbia's wing focused on analyses of the slag deposits. These deposits are complex mixtures of the reinforced carbon/carbon (RCC) constituents, insulation material, and wing structural materials. Identification of melted/solidified Cerachrome insulation (Thermal Ceramics, Inc., Augusta, GA) indicated that the temperatures at the breach had exceeded 1760 C.

  16. [Transbronchoscopic end-tidal carbon dioxide detection for location of the leading bronchus in patients with pneumothorax].

    PubMed

    Zeng, Yiming; Lin, Huihuang

    2015-04-01

    To evaluate the effect of end-tidal carbon dioxide (EtCO2) detection for location of the leading bronchus in patients with pneumothorax. Transbronchoscopic EtCO2 detection was performed in 4 patients with intractable pneumothorax in whom transbronchoscopic balloon detection failed to localize the leading bronchus. A specific bronchus was suspected to be the leading bronchus when its EtCO2 value was significantly lower than that of the main bronchus of the affected lung. After the pleural air leakage was successfully sealed by bronchial occlusion of the suspected bronchus, the EtCO2 was confirmed to indicate the leading bronchus. Transbronchoscopic EtCO2 detection successfully located the leading bronchus in all 4 patients. Transbronchoscopic EtCO2 detection is a new method of locating the leading bronchus in patients with intractable pneumothorax.

  17. Internalization of carbon black and maghemite iron oxide nanoparticle mixtures leads to oxidant production.

    PubMed

    Berg, J Michael; Ho, Shu; Hwang, Wonjoong; Zebda, Rema; Cummins, Kyle; Soriaga, Manuel P; Taylor, Robert; Guo, Bing; Sayes, Christie M

    2010-12-20

    The risk of potential human exposure to mixed nanomaterials in consumer, occupational, and medicinal settings is increasing as nanomaterials enter both the workplace and the marketplace. In this study, we investigated the toxicity of mixed engineered carbon black (ECB) and maghemite iron oxide (Fe(2)O(3)) nanoparticles in a cellular system to understand the mechanism of toxicity and potential methods of toxicity mitigation. Lung epithelial cells (A549) were exposed to mixed Fe(2)O(3) and ECB nanoparticles, mixed Fe(2)O(3) and ECB nanoparticles with the addition of L-ascorbic acid, and mixed Fe(2)O(3) and surface-oxidized engineered carbon black (ox-ECB) nanoparticles. The nanoparticles were characterized using transmission electron microscopy, nitrogen adsorption surface area measurement (BET), X-ray diffraction, and surface charge measurement. The carbon black nanoparticles were also characterized with a reductive capacity assay and by X-ray photoelectron spectroscopy (XPS). The cellular uptake of nanoparticles was analyzed via transmission electron microscopy and fluorescence microscopy; the cellular uptake of iron was quantified using inductively coupled plasma mass spectrometry (ICP-MS). Both the MTT assay and the ethidium homodimer and calcein AM live/dead assay were used to measure cellular proliferation and cytotoxicity, respectively. The dichlorofluorescein diacetate (DCFH-DA) assay was used to measure the intracellular generation of reactive oxygen species. Results show that both Fe(2)O(3) and ECB (or Fe(2)O(3) and ox-ECB) were co-internalized in intracellular vesicles. Additionally, after exposure to the mixture of nanoparticles, the amount of acidified lysosomes increased over time. The cellular uptake of Fe(2)O(3) nanoparticles was unaffected by mixing with ECB. Significant oxidant production occurred in cells exposed to mixed Fe(2)O(3) and ECB, but not in cells exposed to mixed Fe(2)O(3) and ox-ECB or in cells exposed to Fe(2)O(3) and ECB with the

  18. Carbon nanotubes leading the way forward in new generation 3D tissue engineering.

    PubMed

    Hopley, Erin Leigh; Salmasi, Shima; Kalaskar, Deepak M; Seifalian, Alexander M

    2014-01-01

    Statistics from the NHS Blood and Transplant Annual Review show that total organ transplants have increased to 4213 in 2012, while the number of people waiting to receive an organ rose to 7613 that same year. Human donors as the origin of transplanted organs no longer meet the ever-increasing demand, and so interest has shifted to synthetic organ genesis as a form of supply. This focus has given rise to new generation tissue and organ engineering, in the hope of one day designing 3D organs in vitro. While research in this field has been conducted for several decades, leading to the first synthetic trachea transplant in 2011, scaffold design for optimising complex tissue growth is still underexplored and underdeveloped. This is mostly the result of the complexity required in scaffolds, as they need to mimic the cells' native extracellular matrix. This is an intricate nanostructured environment that provides cells with physical and chemical stimuli for optimum cell attachment, proliferation and differentiation. Carbon nanotubes are a popular addition to synthetic scaffolds and have already begun to revolutionise regenerative medicine. Discovered in 1991, these are traditionally used in various areas of engineering and technology; however, due to their excellent mechanical, chemical and electrical properties their potential is now being explored in areas of drug delivery, in vivo biosensor application and tissue engineering. The incorporation of CNTs into polymer scaffolds displays a variety of structural and chemical enhancements, some of which include: increased scaffold strength and flexibility, improved biocompatibility, reduction in cancerous cell division, induction of angiogenesis, reduced thrombosis, and manipulation of gene expression in developing cells. Moreover CNTs' tensile properties open doors for dynamic scaffold design, while their thermal and electrical properties provide opportunities for the development of neural, bone and cardiac tissue constructs

  19. Direct reduction of lead sulfide with carbon and lime; Effect of catalysts:Part i. experimental

    NASA Astrophysics Data System (ADS)

    Rao, Y. K.; El-Rahaiby, S. K.

    1985-09-01

    The direct reduction of lead sulfide with carbon in the presence of lime was investigated in the temperature range 795 to 989 ‡C. Samples of PbS : 4CaO : 4C mixtures prepared from pure constituents were reacted isothermally under a nitrogen atmosphere. The kinetics of reduction were determined for both the uncatalyzed and the catalyzed reduction processes by thermogravimetry. The catalysts used included K2CO3, Li2CO3, Na2CO3, Rb2CO3, NaF, Na2SO4, and the ternary (K, Li, Na)2CO3 eutectic. The extent of catalysis was strong and the rate increase, in some instances, was as large as 10-fold. The following ranking was developed for the various catalysts studied: Li2CO3 > Rb2CO3 > ternary = NaF = K2CO3 > Na2CO3 > Na2SO4. A detailed study of the effect of temperature on catalyzed reaction kinetics was made with PbS:4CaO:4C mixtures doped with 2.5 wt pet ternary (K, Li, Na)2CO3 catalyst. Different catalysts seem to act through different mechanisms. The gas phase emanating from a reacting PbS : 4CaO : 4C was found to contain little or no SO2 and other sulfur-bearing gaseous species. Independent chemical analysis confirmed that virtually all of the sulfur in the charge is retained as CaS(s) in the final reacted solid product.

  20. Preliminary study of lead isotopes in the carbonate-silica veins of Trench 14, Yucca Mountain, Nevada

    SciTech Connect

    Zartman, R.E.; Kwak, L.M.

    1993-12-15

    The sub-vertical carbonate-silica veins filling the Bow Ridge Fault, where exposed in Trench 14 on the east side of Yucca Mountain, carry a lead isotopic signature that can be explained in terms of local sources. Two isotopically distinguishable--silicate and carbonate--fractions of lead are recognized within the vein system as well as in overlying surficial calcrete deposits. The acid-insoluble silicate fraction is contributed largely from the decomposing Miocene volcanic tuff, which forms the wall rock of the fault zone and is a ubiquitous component of the overlying soil. Lead contained in the silicate fraction approaches in isotopic composition that of the Miocene volcanic rocks of Yucca Mountain, but diverges from it in some samples by being more enriched in uranogenic isotopes. The carbonate fraction of lead in both vein and calcrete samples resides dominantly in the HCl- and CH{sub 3}COOH-soluble calcite. HCl evidently also attacks and removes lead from silicate phases, but the milder CH{sub 3}COOH dissolution procedure oftentimes identifies a significantly more radiogenic lead in the calcite. Wind-blown particulate matter brought to the area from Paleozoic and Late Proterozoic limestones in surrounding mountains may be the ultimate source of the calcite. Isotopically more uniform samples suggest that locally the basaltic ash and other volcanic rock have contributed most of the lead to both fractions of the vein system. An important finding of this study is that the data does not require the more exotic mechanisms or origins that have been proposed for the veins. Instead, the remarkably similar lead isotopic properties of the veins to those of the soil calcretes support their interpretation as a surficial, pedogenic phenomenon.

  1. An in situ generated carbon as integrated conductive additive for hierarchical negative plate of lead-acid battery

    NASA Astrophysics Data System (ADS)

    Saravanan, M.; Ganesan, M.; Ambalavanan, S.

    2014-04-01

    In this work, we report an in situ generated carbon from sugar as additive in the Negative Active Mass (NAM) which enhances the charge-discharge characteristics of the lead-acid cells. In situ formed sugar derived carbon (SDC) with leady oxide (LO) provides a conductive network and excellent protection against NAM irreversible lead sulfation. The effect of SDC and carbon black (CB) added negative plates are characterized by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), galvanostatic charge-discharge, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), respectively. The results show that subtle changes in the addition of carbon to NAM led to subsequent changes on the performance during partial-state-of-charge (PSoC) operations in lead-acid cells. Furthermore, SDC added cells exhibit remarkable improvement in the rate capability, active material utilization, cycle performance and charge acceptance compared to that of the conventional CB added cells. The impact of SDC with LO at various synthesis conditions on the electrochemical performance of the negative plate is studied systematically.

  2. Carbon Sequestration: is Science Leading Policy or Will Policy Direct Science?

    NASA Astrophysics Data System (ADS)

    Anderson, A. K.

    2007-12-01

    Climate-related policy is in its infancy on capital hill, as policy makers only recently started to converge on the acceptance that climate change is a credible, scientific reality. Until recently much of the debate and policy decisions have been related to whether or not climate change, or more specifically global warming, is occurring. The climate debate has shifted from discussing the science behind climate change to addressing how we can reduce carbon dioxide emissions. In the 110th Congress, policy makers have come to realize and accept that we, as a nation, are one of the largest global emitters of carbon dioxide to the atmosphere. Geologic carbon sequestration has gained significant congressional attention and is considered to be one of the most promising carbon mitigation tools. In the present Congress, scientific experts have testified before numerous committees about the various caveats of geologic carbon sequestration. As a result, policy has been and is currently being drafted to address the challenges facing large-scale commercial demonstration of geologic sequestration facilities. Policy has been passed through both the House and Senate that is aimed at increasing funding for basic and advanced research, development, and demonstration of small- to large-scale carbon dioxide injection projects. This legislation is only the beginning of a series of legislation that is under development. In the next year, policy will be introduced that will likely address issues related to pore space and mineral rights ownership, regulatory framework for carbon dioxide transport and injection, long-term injection site monitoring protocol, personal and environmental safety, and liability issues, to name a few. Policy is not limited to the technical aspects of carbon capture, transport, and storage, but is also being developed to help stimulate a market that will be operating under climate constraints. Financial incentives have been proposed that will assist industrial

  3. Effect of Carboxylic Functional Group Functionalized on Carbon Nanotubes Surface on the Removal of Lead from Water

    PubMed Central

    Atieh, Muataz Ali; Bakather, Omer Yehya; Al-Tawbini, Bassam; Bukhari, Alaadin A.; Abuilaiwi, Faraj Ahmad; Fettouhi, Mohamed B.

    2010-01-01

    The adsorption mechanism of the removal of lead from water by using carboxylic functional group (COOH) functionalized on the surface of carbon nanotubes was investigated. Four independent variables including pH, CNTs dosage, contact time, and agitation speed were carried out to determine the influence of these parameters on the adsorption capacity of the lead from water. The morphology of the synthesized multiwall carbon nanotubes (MWCNTs) was characterized by using field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) in order to measure the diameter and the length of the CNTs. The diameters of the carbon nanotubes were varied from 20 to 40 nm with average diameter at 24 nm and 10 micrometer in length. Results of the study showed that 100% of lead was removed by using COOH-MCNTs at pH 7, 150 rpm, and 2 hours. These high removal efficiencies were likely attributed to the strong affinity of lead to the physical and chemical properties of the CNTs. The adsorption isotherms plots were well fitted with experimental data. PMID:21350599

  4. 4.4.2 R1, R2 and R3: Leading atom other than carbon

    NASA Astrophysics Data System (ADS)

    Beckwith, A. L. J.

    This document is part of Subvolume A1 `Inorganic Radicals, Metal Complexes and Nonconjugated Carbon Centered Radicals' of Volume 26 `Magnetic Properties of Free Radicals' of Landolt-Börnstein Group II `Molecules and Radicals'.

  5. 4.4.1 R1, R2 and R3: Leading atom is carbon

    NASA Astrophysics Data System (ADS)

    Beckwith, A. L. J.

    This document is part of Subvolume A1 `Inorganic Radicals, Metal Complexes and Nonconjugated Carbon Centered Radicals' of Volume 26 `Magnetic Properties of Free Radicals' of Landolt-Börnstein Group II `Molecules and Radicals'.

  6. Polypyrrole/multi-walled carbon nanotube composite for the solid phase extraction of lead(II) in water samples.

    PubMed

    Sahmetlioglu, Ertugrul; Yilmaz, Erkan; Aktas, Ece; Soylak, Mustafa

    2014-02-01

    A multi-walled carbon nanotubes-polypyrrole conducting polymer nanocomposite has been synthesized, characterized and used for the separation and preconcentration of lead at trace levels in water samples prior to its flame atomic absorption spectrometric detection. The analytical parameters like pH, sample volume, eluent, sample flow rate that were affected the retentions of lead(II) on the new nanocomposite were optimized. Matrix effects were also investigated. Limit of detection and preconcentration factors were 1.1 µg L(-1) and 200, respectively. The adsorption capacity of the nanocomposite was 25.0mg lead(II) per gram composite. The validation of the method was checked by using SPS-WW2 Waste water Level 2 certified reference material. The method was applied to the determination of lead in water samples with satisfactory results.

  7. Canopy structure of sagebrush ecosystems leading to differences in carbon and water fluxes

    NASA Astrophysics Data System (ADS)

    Reed, D. E.; Ewers, B. E.; Peckham, S. D.; Pendall, E. G.; Kelly, R. D.

    2013-12-01

    The sagebrush steppe ecosystem covers nearly 15% of Western North America, and its productivity is sensitive to warming and increasingly variable precipitation. Previous work has shown that interannual variability of precipitation is the largest factor in carbon and water cycling in these semi-arid ecosystems and that the relationship of traditional drivers of fluxes (VPD, net radiation, soil temperature) to carbon and water fluxes as well as ecosystem water use efficiency does not change along an elevation gradient. We seek to expand on that work by using multiple site-years from eddy covariance data near the upper (2469m) and lower (2069m) elevation range of sagebrush to answer the question 'How does canopy structure and canopy leaf area index combine to control the ecosystem carbon and water fluxes from rocky mountain sagebrush ecosystems'. We are answering this question by quantifying ecosystem scale carbon and water using eddy covariance measurements and a standard suite of atmospheric, soil and vegetation monitoring instruments. This data will be used with the Terrestrial Regional Ecosystem Exchange Simulator (TREES) Bayesian framework model that utilizes a coupled plant hydraulic and carbon uptake. For this work we use the TREES model to simulate canopy structure and leaf area based on seven years of eddy covariance data from the two different locations. This canopy information will be compared with canopy structure ground measurements within the eddy covariance footprint, and then we will compare the relationship between canopy structure and ecosystem fluxes. During well watered growing season time periods, the high elevation site has average water flux of 1.06 mmol m-2 s-1 and carbon flux of 1.54 μmol m-2 s-1 of uptake. Average water and carbon fluxes at the lower elevation site were 0.84 mmol m-2 s-1 and 1.09 μmol m-2 s-1 of uptake respectively. This is a reduction of 20% for water flux and 30% and carbon flux down the elevation gradient. With the

  8. Enhanced performance of Zn(II)-doped lead-acid batteries with electrochemical active carbon in negative mass

    NASA Astrophysics Data System (ADS)

    Xiang, Jiayuan; Hu, Chen; Chen, Liying; Zhang, Dong; Ding, Ping; Chen, Dong; Liu, Hao; Chen, Jian; Wu, Xianzhang; Lai, Xiaokang

    2016-10-01

    The effect and mechanism of Zn(II) on improving the performances of lead-acid cell with electrochemical active carbon (EAC) in negative mass is investigated. The hydrogen evolution of the cell is significantly reduced due to the deposition of Zn on carbon surface and the increased porosity of negative mass. Zn(II) additives can also improve the low-temperature and high-rate capacities of the cell with EAC in negative mass, which ascribes to the formation of Zn on lead and carbon surface that constructs a conductive bridge among the active mass. Under the co-contribution of EAC and Zn(II), the partial-state-of-charge cycle life is greatly prolonged. EAC optimizes the NAM structure and porosity to enhance the charge acceptance and retard the lead sulfate accumulation. Zn(II) additive reduces the hydrogen evolution during charge process and improves the electric conductivity of the negative electrode. The cell with 0.6 wt% EAC and 0.006 wt% ZnO in negative mass exhibits 90% reversible capacity of the initial capacity after 2100 cycles. In contrast, the cell with 0.6 wt% EAC exhibits 84% reversible capacity after 2100 cycles and the control cell with no EAC and Zn(II) exhibits less than 80% reversible capacity after 1350 cycles.

  9. Hydroxylamine-O-sulfonamide is a versatile lead compound for the development of carbonic anhydrase inhibitors.

    PubMed

    Di Fiore, Anna; Vergara, Alessandro; Caterino, Marco; Alterio, Vincenzo; Monti, Simona M; Ombouma, Joanna; Dumy, Pascal; Vullo, Daniela; Supuran, Claudiu T; Winum, Jean-Yves; De Simone, Giuseppina

    2015-07-21

    Hydroxylamine-O-sulfonamide, a molecule incorporating two zinc-binding groups (ZBGs), has been investigated as a carbonic anhydrase inhibitor (CAI) by means of kinetic, crystallographic and Raman spectroscopy studies, highlighting interesting results on its mechanism of action. These data can be exploited to design new, effective and selective CAIs.

  10. [Adsorption kinetics and mechanism of lead (II) on polyamine-functionalized mesoporous activated carbon].

    PubMed

    Li, Kun-Quan; Wang, Yan-Jin; Yang, Mei-Rong; Zhu, Zhi-Qiang; Zheng, Zheng

    2014-08-01

    Bagasse mesoporous carbon was prepared by microwave assisted H3 PO4 activation. Amido and imido groups were modified with ethanediamine on the channels' surface of mesoporous carbon through nitric oxidation and amide reaction. The influence of Pb(II) concentration, adsorption time on Pb(II) adsorption on the ethanediamine-modified mesoporous carbon (AC-EDA) was investigated. The adsorption kinetics and mechanism were also discussed. The results showed that AC-EDA had a great performance for Pb(II) adsorption, and more than 70% of Pb(II) was adsorbed in 5 minutes. The adsorption amount of Pb(II) on the carbon increased with the increase of solution pH in acidic conditions. It was found that AC-EDA had different binding energies on different adsorption sites for Pb(II) separation. The Pb(II) adsorption process on AC-EDA was controlled by intra-particle diffusion in the first 3 min, and then film diffusion played the important pole on the adsorption. The adsorption amount increased with the increase of temperature, indicating the adsorption was an endothermic reaction. The high adsorption energy (> 11 kJ x mol(-1)) implied that the) adsorption was a chemical adsorption. The XPS of AC-EDA before and after Pb(II) adsorption showed that the polyamine group was involved in the adsorption, and should be a main factor of the high efficient adsorption.

  11. Lead Adsorption into Activated Carbon: A Critical Review of the Literature

    EPA Science Inventory

    Lead has been widely used in many industries due to its desirable chemical and physical properties such as its malleability and resistance to corrosion. However, Lead poisoning is a serious health hazard that causes severe damage to multiple target organs including kidney, liver,...

  12. Lead Adsorption into Activated Carbon: A Critical Review of the Literature

    EPA Science Inventory

    Lead has been widely used in many industries due to its desirable chemical and physical properties such as its malleability and resistance to corrosion. However, Lead poisoning is a serious health hazard that causes severe damage to multiple target organs including kidney, liver,...

  13. Lead acid battery performance and cycle life increased through addition of discrete carbon nanotubes to both electrodes

    NASA Astrophysics Data System (ADS)

    Sugumaran, Nanjan; Everill, Paul; Swogger, Steven W.; Dubey, D. P.

    2015-04-01

    Contemporary applications are changing the failure mechanisms of lead acid batteries. Sulfation at the negative electrode, acid stratification, and dendrite formation now precede positive electrode failures such as grid corrosion and active material shedding. To attenuate these failures, carbon has been explored as a negative electrode additive to increase charge acceptance, eliminate sulfation, and extend cycle life. Frequently, however, carbon incorporation decreases paste density and hinders manufacturability. Discrete carbon nanotubes (dCNT), also known as Molecular Rebar®, are lead acid battery additives which can be stably incorporated into either electrode to increase charge acceptance and cycle life with no change to paste density and without impeding the manufacturing process. Here, full-scale automotive batteries containing dCNT in the negative electrode or both negative and positive electrodes are compared to control batteries. dCNT batteries show little change to Reserve Capacity, improved Cold Cranking, increased charge acceptance, and enhanced overall system efficiency. Life cycle tests show >60% increases when dCNT are incorporated into the negative electrode (HRPSoC/SBA) and up to 500% when incorporated into both electrodes (SBA), with water loss per cycle reduced >20%. Failure modes of cycled batteries are discussed and a hypothesis of dCNT action is introduced: the dCNT/Had Overcharge Reaction Mechanism.

  14. Zero-valent iron doped carbons readily developed from sewage sludge for lead removal from aqueous solution.

    PubMed

    Su, Yiming; Sun, Xiaoya; Zhou, Xuefei; Dai, Chaomeng; Zhang, Yalei

    2015-10-01

    Low-cost but high-efficiency composites of iron-containing porous carbons were prepared using sewage sludge and ferric salts as raw materials. Unlike previous time- and energy-consuming manufacturing procedures, this study shows that pyrolyzing a mixture of sludge and ferric salt can produce suitable composites for lead adsorption. The specific surface area, the total pore volume and the average pore width of the optimal composite were 321m(2)/g, 0.25cm(3)/g, and 3.17nm, respectively. X-ray diffraction analysis indicated that ferric salt favored the formation of metallic iron, while Fourier transform infrared spectroscopy revealed the formation of hydroxyl and carboxylic groups. The result of batch tests indicated that the adsorption capacity of carbons activated with ferric salt could be as high as 128.9mg/g, while that of carbons without activation was 79.1mg/g. The new manufacturing procedure used in this study could save at least 19.5kJ of energy per gram of activated carbon.

  15. Quasi-Static 3-Point Reinforced Carbon-Carbon Bend Test and Analysis for Shuttle Orbiter Wing Leading Edge Impact Damage Thresholds

    NASA Technical Reports Server (NTRS)

    Fasanella, Edwin L.; Sotiris, Kellas

    2006-01-01

    Static 3-point bend tests of Reinforced Carbon-Carbon (RCC) were conducted to failure to provide data for additional validation of an LS-DYNA RCC model suitable for predicting the threshold of impact damage to shuttle orbiter wing leading edges. LS-DYNA predictions correlated well with the average RCC failure load, and were good in matching the load vs. deflection. However, correlating the detectable damage using NDE methods with the cumulative damage parameter in LS-DYNA material model 58 was not readily achievable. The difficulty of finding internal RCC damage with NDE and the high sensitivity of the mat58 damage parameter to the load near failure made the task very challenging. In addition, damage mechanisms for RCC due to dynamic impact of debris such as foam and ice and damage mechanisms due to a static loading were, as expected, not equivalent.

  16. Advanced X-Ray Inspection of Reinforced Carbon Composite Materials on the Orbiter Leading Edge Structural Subsystem (LESS)

    NASA Technical Reports Server (NTRS)

    Hernandez, Jose M.; Berry, Robert F.; Osborn, Robin; Bueno, Clifford; Osterlitz, Mark; Mills, Richard; Morris, Philip; Phalen, Robert; McNab, Jim; Thibodeaux, Tahanie; Thompson, Kyle

    2004-01-01

    The post return-to-flight (RTF) inspection methodology for the Orbiter Leading Edge Structural Subsystem (LESS) is currently being defined. Numerous NDT modalities and techniques are being explored to perform the flight-to-flight inspections of the reinforced carbon/carbon (RCC) composite material for impact damage, general loss of mass in the bulk layers, or other anomalous conditions that would pose risk to safe return upon re-entry. It is possible to have an impact upon ascent that is not visually observable on the surface, yet causes internal damage. Radiographic testing may be a useful NDT technique for such occurrences. The authors have performed radiographic tests on full-sized mock samples of LESS hardware with embedded image quality phantoms. Digitized radiographic film, computed radiography and flat panel digital real-time radiography was acquired using a GE Eresco 200 x-ray tube, and Se-75 and Yb-169 radioisotopes.

  17. The use of activated carbon and graphite for the development of lead-acid batteries for hybrid vehicle applications

    NASA Astrophysics Data System (ADS)

    Fernández, M.; Valenciano, J.; Trinidad, F.; Muñoz, N.

    Future vehicle applications require the development of reliable and long life batteries operating under high-rate partial-state-of-charge (HRPSoC) working conditions. This paper updates work carried out to develop spiral wound valve-regulated batteries for vehicles with different hybridisation degrees, ranging from stop-start to mild hybrid applications. In order to develop a battery that can withstand the hard operating conditions that the work at High Rate Partial-State-of-Charge (HRPSoC) implies, it is necessary to modify the negative AM formulation by using special, additives like carbon and graphite that reduce lead sulphate accumulation during HRPSoC cycling within in the negative plate. Several batches of negative active material (NAM) with the addition of graphites of different types, as well as combinations of graphite and activated carbons, have been made on 6 V 24 Ah Spiral wound modules. Electrical results show a dramatic increase of the charge acceptance at different SoC's that for some combinations approach 200%. On the other hand, on cycle life according to EUCAR Power Assist cycling, values in the range 200,000-220,000 cycles have been obtain in most part of the batch. This represents a capacity turnover of 5000-5500 times the nominal capacity. The paper is divided into three parts. The first part is devoted to identify the cause of failure of the negative plate on Power Assist Cycle Life, that turned to be the development of high amounts of lead sulphate and its accumulation on the surface of the plate. The second part covers the addition of carbon and graphite of low SSA to NAM and finally the third part is dedicated to the test of additions of medium/high SSA carbon to NAM with the specific objective of trying to implement the supercapacitor effect inside the battery.

  18. Saccharin: a Lead Compound for Structure-Based Drug Design of Carbonic Anhydrase IX Inhibitors

    PubMed Central

    Mahon, Brian P.; Hendon, Alex M.; Driscoll, Jenna M.; Rankin, Gregory M.; Poulsen, Sally-Ann; Supuran, Claudiu T.; McKenna, Robert

    2015-01-01

    Carbonic anhydrase IX (CA IX) is a key modulator of aggressive tumor behavior and a prognostic marker and target for several cancers. Saccharin (SAC) based compounds may provide an avenue to overcome CA isoform specificity, as they display both nanomolar affinity and preferential binding, for CA IX compared to CA II (>50-fold for SAC and >1000-fold when SAC is conjugated to a carbohydrate moiety). The X-ray crystal structures of SAC and a SAC-carbohydrate conjugate bound to a CA IX-mimic are presented and compared to CA II. The structures provide substantial new insight into the mechanism of SAC selective CA isoform inhibition. PMID:25614109

  19. Saccharin: a lead compound for structure-based drug design of carbonic anhydrase IX inhibitors.

    PubMed

    Mahon, Brian P; Hendon, Alex M; Driscoll, Jenna M; Rankin, Gregory M; Poulsen, Sally-Ann; Supuran, Claudiu T; McKenna, Robert

    2015-02-15

    Carbonic anhydrase IX (CA IX) is a key modulator of aggressive tumor behavior and a prognostic marker and target for several cancers. Saccharin (SAC) based compounds may provide an avenue to overcome CA isoform specificity, as they display both nanomolar affinity and preferential binding, for CA IX compared to CA II (>50-fold for SAC and >1000-fold when SAC is conjugated to a carbohydrate moiety). The X-ray crystal structures of SAC and a SAC-carbohydrate conjugate bound to a CA IX-mimic are presented and compared to CA II. The structures provide substantial new insight into the mechanism of SAC selective CA isoform inhibition. Published by Elsevier Ltd.

  20. High salinity leads to accumulation of soil organic carbon in mangrove soil.

    PubMed

    Kida, Morimaru; Tomotsune, Mitsutoshi; Iimura, Yasuo; Kinjo, Kazutoshi; Ohtsuka, Toshiyuki; Fujitake, Nobuhide

    2017-06-01

    Although mangrove forests are one of the most well-known soil organic carbon (SOC) sinks, the mechanism underlying SOC accumulation is relatively unknown. High net primary production (NPP) along with the typical bottom-heavy biomass allocation and low soil respiration (SR) have been considered to be responsible for SOC accumulation. However, an emerging paradigm postulates that SR is severely underestimated because of the leakage of dissolved inorganic carbon (DIC) in groundwater. Here we propose a simple yet unique mechanism for SOC accumulation in mangrove soils. We conducted sequential extraction of water extractable organic matter (WEOM) from mangrove soils using ultrapure water and artificial seawater, respectively. A sharp increase in humic substances (HS) concentration was observed only in the case of ultrapure water, along with a decline in salinity. Extracted WEOM was colloidal, and ≤70% of it re-precipitated by the addition of artificial seawater. These results strongly suggest that HS is selectively flocculated and maintained in the mangrove soils because of high salinity. Because sea salts are a characteristic of any mangrove forest, high salinity may be one of mechanisms underlying SOC accumulation in mangrove soils.

  1. Simultaneous detection of ultratrace lead and copper with gold nanoparticles patterned on carbon nanotube thin film.

    PubMed

    Bui, Minh-Phuong Ngoc; Li, Cheng Ai; Han, Kwi Nam; Pham, Xuan-Hung; Seong, Gi Hun

    2012-04-21

    Highly sensitive detection of a Pb(2+)-Cu(2+) mixture using gold nanoparticles patterned on single-walled carbon nanotube (AuNP-SWCNT) film is reported. The gold nanoparticles were deposited electrochemically on carbon nanotube film using a cyclic voltammetry technique. The film showed a homogeneous size and density that could be easily controlled by the potential scanning cycle and gold precursor concentration. Square wave stripping voltammetry (SWSV) was applied to the simultaneous detection of Pb(2+) and Cu(2+) under optimized conditions. The AuNP-SWCNT electrode exhibited a high increase in sensitivity with a limit of detection of 0.546 ppb (R(2) = 0.984) and 0.613 ppb (R(2) = 0.991) for Pb(2+) and Cu(2+) ions, respectively, in a mixture of Pb(2+)-Cu(2+) solution (S/N = 3, n = 5), and a good linear response in the range from 3.31 ppb to 22.29 ppb. The electrode exhibited high reproducibility in repetitive measurements with a relative standard deviation as low as 4.2% and 2.6% for Pb(2+) and Cu(2+) ions, respectively. An interference study showed that Sb(3+), As(3+), Zn(2+), Ca(2+), and Na(+) ions did not have a significant effect. This study demonstrated an alternative approach to the rapid and reliable detection of heavy metals of environmental interest.

  2. Nonlinear Rayleigh waves to detect initial damage leading to stress corrosion cracking in carbon steel

    NASA Astrophysics Data System (ADS)

    Matlack, K. H.; Kim, J.-Y..; Jacobs, L. J.; Qu, J.; Singh, P. M.

    2012-05-01

    This research experimentally investigates second harmonic generation of Rayleigh waves propagating through carbon steel samples damaged in a stress corrosion environment. Damage from stress corrosion cracking is of major concern in nuclear reactor tubes and in gas and fuel transport pipelines. For example, certain types of stress corrosion cracking (SCC) account for more failures in steam generator tubes than most other damage mechanisms, yet these cracks do not initiate until late in the structure's life. Thus, there is a need to be able to measure the damage state prior to crack initiation, and it has been shown that the acoustic nonlinearity parameter - the parameter associated with second harmonic generation - is sensitive to microstructural evolution. In this work, samples are immersed in a sodium carbonate-bicarbonate solution, which typically forms in the soil surrounding buried pipelines affected by SCC, and held at yield stress for 5-15 days to the onset of stress corrosion cracking. Measurements of second harmonic generation with Rayleigh waves are taken intermittently to relate cumulative damage prior to macroscopic cracking to nonlinear wave propagation. Experimental results showing changes in second harmonic generation due to stress corrosion damage are presented.

  3. Modified titanium foil's surface by high temperature carbon sintering method as the substrate for bipolar lead-acid battery

    NASA Astrophysics Data System (ADS)

    Lang, Xiaoshi; Wang, Dianlong; Zhu, Junsheng

    2014-12-01

    Titanium foil can be a type of ideal material as the substrate for bipolar lead-acid battery. However, it can't be directly used because it can be oxidized in the high voltage and strong oxidizing conditions. In this paper, we coat the titanium suboxide on the titanium foil surface by means of the high temperature carbon sintering method for the improvement of corrosion resistance of titanium metal and use it as the substrate to bipolar lead-acid battery to study its effect on the battery performances. Modified titanium foils are characterized by SEM, XRD, corrosion resistance test and electronic conductivity test. The electrochemical properties of the bipolar lead-acid battery are investigated by constant current charge/discharge method. The results demonstrate that the titanium foil carbon-sintered at 800 °C for 2 h has the most excellent chemical stability and electronic conductivity. Initial specific capacities of positive active material of bipolar lead-acid battery with modified titanium as the substrate at 0.25C, 0.5C, 1C and 2C discharge rate are 99.29 mAh g-1, 88.93 mAh g-1, 77.54 mAh g-1, and 65.41 mAh g-1. After 50 cycles, the specific capacity of positive active material at 0.5C is 81.36 mAh g-1 and after 100 cycles, the specific capacity at 1C is 61.92 mAh g-1.

  4. Characterization of a carbon paste electrode modified with tripolyphosphate-modified kaolinite clay for the detection of lead.

    PubMed

    Gómez, Yoleydis; Fernández, Lenys; Borrás, Carlos; Mostany, Jorge; Scharifker, Benjamín

    2011-09-15

    We report about the use of carbon paste electrode modified with kaolinite for analytical detection of trace lead(II) in domestic water by differential pulse voltammetry. Kaolinite clay was modified with tripolyphosphate (TPP) by impregnation method. The results show that TPP in kaolinite clay plays an important role in the accumulation process of Pb(II) on the modified electrode surface. The electroanalytical procedure for determination of Pb(II) comprised two steps: chemical accumulation of the analyte under open-circuit conditions, followed by electrochemical detection of the pre-concentrated species using differential pulse voltammetry. The analytical performance of this system has been explored by studying the effects of preconcentration time, carbon paste composition, pH, supporting electrolyte concentration, as well as interferences due to other ions. The calculated detection limit based on the variability of a blank solution (3s(b) criterion) for 10 measurements was 8.4×10(-8) mol L(-1), and the sensitivity determined from the slope of the calibration graph was 0.910 mol L(-1). The reproducibility (RSD) for five replicate measurements at 1.0 mg L(-1) lead level was 1.6%. The results indicate that this electrode is sensitive and effective for the determination of Pb(2+).

  5. Does Iron Fertilization Lead to Enhanced Carbon Sequestration? A Synthesis of Polar Star Results.

    SciTech Connect

    Buesseler, K.O.

    2002-12-01

    This research synthesized activities related to work conducted as part of the Southern Ocean Iron Experiment (SOFeX) which investigated the effects of iron fertilization on enhanced carbon sequestration. The primary interest was in the fate of sinking particles which carry carbon to the deep ocean, where it can be sequestered from the atmosphere for >100-1000 year time scales. This was accomplished through direct measurements of thorium-234, a naturally occurring particle reactive radionuclide that traces shallow particle export; SF6 measurements to track the position of the Fe fertilized region; and the collection of ancillary data and samples to augment the study of major C, nutrient and elemental budgets as well as appropriate samples for biological study. Results of this work show a small, but progressively increasing flux of particulate organic C to depth as a consequence of Fe fertilization. This is the first data set to show any effect of Fe fertilization on C sequestration in the Southern Ocean. The changes in particle export during SOFeX are significant, but only possible to detect given what is arguably the largest 234Th data set ever collected as part of an oceanographic experiment. Most prior 234Th studies, simply use a steady-state approximation and ignore advective and diffusive fluxes in the calculation of 234Th fluxes. High resolution time-series of average 0-50m 234Th activities in and out of the Southern patch find a clear steady decrease in 234Th flux that is slightly larger in vs. out of the Fe fertilized patch. This decrease must be included in the full 234Th flux calculation and the deliberate tagging of this water mass with SF6 combined with time-series sampling allowed for a careful evaluation of this non-steady state (NSS) term. Likewise, the addition of SF6 allows for the evaluation of vertical exchange (via the gradient of SF6 below the patch) and dilution effects (after correction for atmospheric losses). In most set tings these physical

  6. Changes in soil thermal regime lead to substantial shifts in carbon and energy fluxes in drained Arctic tundra

    NASA Astrophysics Data System (ADS)

    Goeckede, M.; Kwon, M. J.; Kittler, F.; Heimann, M.; Zimov, N.; Zimov, S. A.

    2016-12-01

    Climate change impacts in the Arctic will not only depend on future temperature trajectories in this region. In particular, potential shifts in hydrologic regimes, e.g. linked to altered precipitation patterns or changes in topography following permafrost degradation, can dramatically modify ecosystem feedbacks to warming. Here, we analyze how severe drainage affects both biogeochemical and biogeophysical processes within a formerly wet Arctic tundra, with a special focus on the interactions between hydrology and soil temperatures, and related effects on the fluxes of carbon and energy. Our findings are based on year-round observations from a decade-long drainage experiment conducted near Chersky, Northeast Siberia. Through our multi-disciplinary observations we can document that the drainage triggered a suite of secondary changes in ecosystem properties, including e.g. adaptation processes in the vegetation community structure, or shifts in snow cover regime. Most profoundly, a combination of low heat capacity and reduced heat conductivity in dry organic soils lead to warmer soil temperatures near the surface, while deeper soil layers remained colder. These changes in soil thermal regime reduced the contribution of deeper soil layers with older carbon pools to overall ecosystem respiration, as documented through radiocarbon signals. Regarding methane, the observed steeper temperature gradient along the vertical soil profile slowed down methane production in deep layers, while promoting CH4 oxidation near the surface. Taken together, both processes contributed to a reduction in CH4 emissions up to a factor of 20 following drainage. Concerning the energy budget, we observed an intensification of energy transfer to the lower atmosphere, particularly in form of sensible heat, but the reduced energy transfer into deeper soil layers also led to systematically shallower thaw depths. Summarizing, drainage may contribute to slow down decomposition of old carbon from deep

  7. Environmental forcing does not lead to variation in carbon isotope content of forest soil respiration

    NASA Astrophysics Data System (ADS)

    Bowling, David; Egan, Jocelyn; Hall, Steven; Risk, David

    2015-04-01

    Recent studies have highlighted fluctuations in the carbon isotope content (δ13C) of CO2 produced by soil respiration. These have been correlated with diel cycles of environmental forcing (e.g., soil temperature), or with synoptic weather events (e.g., rain events and pressure-induced ventilation). We used an extensive suite of observations to examine these phenomena over two months in a subalpine forest in Colorado, USA (the Niwot Ridge AmeriFlux site). Measurements included automated soil respiration chambers and automated measurements of the soil gas profile. We found 1) no diel change in the δ13C of the soil surface flux or the CO2 produced in the soil (despite strong diel change in surface flux rate), 2) no change in δ13C following wetting (despite a significant increase in soil flux rate), and 3) no evidence of pressure-induced ventilation of the soil. Measurements of the δ13C of surface CO2 flux agreed closely with the isotopic composition of soil CO2 production calculated using soil profile measurements. Temporal variation in the δ13C of surface flux was relatively minor and unrelated to measured environmental variables. Deep in the soil profile, results conform to established theory regarding diffusive soil gas transport and isotopic fractionation, and suggest that sampling soil gas at a depth of several tens of centimeters is a simple and effective way to assess the mean δ13C of the surface flux.

  8. Adsorption of lead ions from aqueous solution using porous carbon derived from rubber tires: experimental and computational study.

    PubMed

    Saleh, Tawfik A; Gupta, Vinod K; Al-Saadi, Abdulaziz A

    2013-04-15

    Effective activated porous carbon (AC) was prepared by thermal treatment of waste rubber tires and was further activated using oxidizing agents like nitric acid and hydrogen peroxide. The tire-derived porous carbon was characterized by means of FTIR and X-ray diffraction. Careful analysis of the IR spectra of the synthesized AC reveals a number of bands centered at about 3400, 2350, 1710, 1650, and 1300-1000cm(-1), proving the existence of hydroxyl and carboxylic groups on the surface of AC in addition to CC double bonds. The developed AC was tested and evaluated as a potential adsorbent for the removal of lead (II) ions. Experimental parameters, such as contact time, initial concentration, adsorbent dosage, and pH were optimized. AC was effective in a pH range between 4 and 7 with a highest uptake of lead ions at pH 5 and 6. For further understanding of the chemistry behind the process, density functional theory (DFT) calculations were performed at the B3LYP/6-31G(d) level adopting a functionalized pyrene molecule as a model. The binding energy of Pb(II) ion toward carboxylic acid, carbonyl, and hydroxyl groups was calculated. A binding energy in the range of 310-340kcal/mol, which is considered to be high and to be indicative of a chemisorptions process, was predicted. The adsorption of the lead ion toward the CO groups in relatively all cases shows more stable binding compared to the sorption toward the alcohol groups. Copyright © 2013 Elsevier Inc. All rights reserved.

  9. Vegetation feedbacks of nutrient addition lead to a weaker carbon sink in an ombrotrophic bog.

    PubMed

    Larmola, Tuula; Bubier, Jill L; Kobyljanec, Christine; Basiliko, Nathan; Juutinen, Sari; Humphreys, Elyn; Preston, Michael; Moore, Tim R

    2013-12-01

    To study vegetation feedbacks of nutrient addition on carbon sequestration capacity, we investigated vegetation and ecosystem CO2 exchange at Mer Bleue Bog, Canada in plots that had been fertilized with nitrogen (N) or with N plus phosphorus (P) and potassium (K) for 7-12 years. Gross photosynthesis, ecosystem respiration, and net CO2 exchange were measured weekly during May-September 2011 using climate-controlled chambers. A substrate-induced respiration technique was used to determine the functional ability of the microbial community. The highest N and NPK additions were associated with 40% less net CO2 uptake than the control. In the NPK additions, a diminished C sink potential was due to a 20-30% increase in ecosystem respiration, while gross photosynthesis rates did not change as greater vascular plant biomass compensated for the decrease in Sphagnum mosses. In the highest N-only treatment, small reductions in gross photosynthesis and no change in ecosystem respiration led to the reduced C sink. Substrate-induced microbial respiration was significantly higher in all levels of NPK additions compared with control. The temperature sensitivity of respiration in the plots was lower with increasing cumulative N load, suggesting more labile sources of respired CO2 . The weaker C sink potential could be explained by changes in nutrient availability, higher woody : foliar ratio, moss loss, and enhanced decomposition. Stronger responses to NPK fertilization than to N-only fertilization for both shrub biomass production and decomposition suggest that the bog ecosystem is N-P/K colimited rather than N-limited. Negative effects of further N-only deposition were indicated by delayed spring CO2 uptake. In contrast to forests, increased wood formation and surface litter accumulation in bogs seem to reduce the C sink potential owing to the loss of peat-forming Sphagnum.

  10. Electrochemical generation of volatile lead species using a cadmium cathode: Comparison with graphite, glassy carbon and platinum cathodes

    NASA Astrophysics Data System (ADS)

    Sáenz, María; Fernández, Lenys; Domínguez, José; Alvarado, José

    2012-05-01

    Working electrodes made out of pyrolytic graphite, glassy carbon, platinum and cadmium were compared for the electrochemical generation of volatile lead species. The same electrolytic cell, using each of the different working electrodes was coupled to an atomic absorption spectrometer and the experimental conditions were optimized in each case, using a univariate approach, to produce the maximum possible amount of volatile lead species. The experiments were focused on the variation of cathode hydrogen overvoltage by the application of a constant current during analysis. Under optimum conditions the performance of the electrochemical hydride generator cell should depend on the cathode material selected due to the different hydrogen overpotential of each material. The lead absorbance signal was taken as a measure of the efficiency of volatile lead species production. Best results were obtained using the Cd cathode, due to its relatively highest hydrogen overpotential, a carrier gas (Ar) flow rate of 55 mL min- 1 an electrolytic current of 0.8 A and a catholyte (HCl) concentration 0.05 mol L- 1. The analytical figures of merit of the method using the Cd electrode were evaluated and the susceptibility of the method to interferences was assessed by its application to the determination of trace amounts of lead in the presence of the most significant interferents. The calibration curve was linear between 0.5 and 15 μg L- 1 Pb. Detection limits and characteristic mass values were 0.21 μg L- 1 and 0.26 μg L- 1 respectively. A bovine liver standard reference material and a spiked urine sample were analyzed to check accuracy.

  11. Leads and lags between the Antarctic temperature and carbon dioxide during the last deglaciation

    NASA Astrophysics Data System (ADS)

    Gest, Léa; Parrenin, Frédéric; Raynaud, Dominique; Fudge, Tyler J.

    2017-04-01

    To understand causal relationships in past climate variations, it is essential to have accurate chronologies of paleoclimate records. Ice cores in Antarctica provide important paleoclimate variables, such as local temperature and global atmospheric CO2. Unfortunately, temperature is recorded in the ice while CO2 is recorded in the enclosed air bubbles. The ages of the former and of the latter are different since air is trapped at 50-120 m below the surface. For the last deglacial warming, 18,000 to 11,000 years ago, Parrenin et al. (Science, 2013) inferred that CO2 and Antarctic temperature started to increase in phase while CO2 lagged temperature at the beginning of the Holocene period. However, this study suffers from various uncertainties that we tried to address in the current study. First, Antarctic temperature was inferred from a stack of 5 Antarctic ice cores that were not always accurately synchronized. Here we use a stack of 4 Antarctic ice cores which are all accurately synchronized thanks to volcanic peak matching. Second, Parrenin et al. (Science, 2013) used a relatively low-resolution CO2 record from the EPICA Dome C ice core. Here, we use the more recent and higher resolution CO2 record from the West Antarctic Ice Sheet Divide ice core. Third, the air trapping depth was deduced on the low accumulation EPICA Dome C ice core using the gravitational enrichment of the δ15N isotopes and assuming a zero convective depth, a hypothesis that was not proved. Here, we use the higher accumulation WAIS Divide ice core, where the ice-air age shift is one order of magnitude smaller, and therefore better constrained. Finally, we use an improved mathematical method to infer break points in the Antarctic temperature and atmospheric CO2 records. We find that, at the onset of the last deglaciation and the onset of the Bølling-Allerød period, the phasing between CO2 and Antarctic temperature is negligible within a range of 130 years. Then CO2 slightly leads by 200

  12. Lead titanate/cyclic carbonate dependence on ionic conductivity of ferro/acrylate blend polymer composites

    NASA Astrophysics Data System (ADS)

    Jayaraman, R.; Vickraman, P.; Subramanian, N. M. V.; Justin, A. Simon

    2016-05-01

    Impedance, XRD, DSC and FTIR studies had been carried out for PVdF-co-HFP/LIBETI based system for three plasticizer (EC/DMC) - filler (PbTiO3) weight ratios. The enhanced conductivity 4.18 × 10-5 Scm-1 was noted for 57.5 wt% -7.5 wt% plasticizer - filler. while blending PEMA to PVdF-co-HFP respectively 7.5: 22.5 wt % (3/7), 15 wt%: 15 wt % (5/5) and 22.5wt %: 7.5 wt % (7/3), the improved conductivity was noted for 3/7 ratio 1.22 × 10-5 S cm-1 and its temperature dependence abide Arrhenius behavior. The intensity of peaks in XRD diffractogram registered dominance of lead titanate, from 2θ = 10° to 80° and absence of VdF crystallites (α+β phase) was noted. In DSC studies, the presence of the exotherm events, filler effect was distinctively seen exhibiting recrystallization of VdF crystallites. In blending PEMA, however, no trace of exotherms was found suggestive of PEMA better inhibiting recrystallization. FTIR study confirmed molecular interactions of various constituents in the vibrational band 500 - 1000 cm-1 both in pristine PVdF-co-HFP and PEMA blended composites with reference to C-F stretching, C-H stretching and C=O carbonyl bands.

  13. Lead titanate/cyclic carbonate dependence on ionic conductivity of ferro/acrylate blend polymer composites

    SciTech Connect

    Jayaraman, R.; Vickraman, P. Subramanian, N. M. V.; Justin, A. Simon

    2016-05-23

    Impedance, XRD, DSC and FTIR studies had been carried out for PVdF-co-HFP/LIBETI based system for three plasticizer (EC/DMC) – filler (PbTiO3) weight ratios. The enhanced conductivity 4.18 × 10{sup −5} Scm{sup −1} was noted for 57.5 wt% −7.5 wt% plasticizer – filler. while blending PEMA to PVdF-co-HFP respectively 7.5: 22.5 wt % (3/7), 15 wt%: 15 wt % (5/5) and 22.5wt %: 7.5 wt % (7/3), the improved conductivity was noted for 3/7 ratio 1.22 × 10{sup −5} S cm{sup −1} and its temperature dependence abide Arrhenius behavior. The intensity of peaks in XRD diffractogram registered dominance of lead titanate, from 2θ = 10° to 80° and absence of VdF crystallites (α+β phase) was noted. In DSC studies, the presence of the exotherm events, filler effect was distinctively seen exhibiting recrystallization of VdF crystallites. In blending PEMA, however, no trace of exotherms was found suggestive of PEMA better inhibiting recrystallization. FTIR study confirmed molecular interactions of various constituents in the vibrational band 500 – 1000 cm{sup −1} both in pristine PVdF-co-HFP and PEMA blended composites with reference to C-F stretching, C-H stretching and C=O carbonyl bands.

  14. Goethite surface reactivity: a macroscopic investigation unifying proton, chromate, carbonate, and lead(II) adsorption.

    PubMed

    Villalobos, Mario; Pérez-Gallegos, Ayax

    2008-10-15

    The goethite surface structure has been extensively studied, but no convincing quantitative description of its highly variable surface reactivity as inversely related to its specific surface area (SSA) has been found. The present study adds experimental evidence and provides a unified macroscopic explanation to this anomalous behavior from differences in average adsorption capacities, and not in average adsorption affinities. We investigated the chromate anion and lead(II) cation adsorption behavior onto three different goethites with SSA varying from 50 to 94 m(2)/g, and analyzed an extensive set of published anion adsorption and proton charging data for variable SSA goethites. Maximum chromate adsorption was found to occupy on average from 3.1 to 9.7 sites/nm(2), inversely related to SSA. Congruency of oxyanion and Pb(II) adsorption behavior based on fractional site occupancy using these values, and a site density analysis suggest that: (i) ion binding occurs to singly and doubly coordinated sites, (ii) proton binding occurs to singly and triply coordinated sites (ranging from 6.2 to 8 total sites/nm(2), in most cases), and (iii) a predominance of (210) and/or (010) faces explains the high reactivity of low SSA goethites. The results imply that the macroscopic goethite adsorption behavior may be predicted without a need to investigate extensive structural details of each specific goethite of interest.

  15. Studies Conducted of Sodium Carbonate Contaminant Found on the Wing Leading Edge and the Nose Cap of the Space Shuttle Orbiter

    NASA Technical Reports Server (NTRS)

    Jacobson, Nathan S.; Palou, Jaime J.

    2003-01-01

    In early 2001, three of the space shuttle orbiters were found to have a sodium carbonate contaminant on the wing leading edge and nose cap. These parts are made of a reinforced carbon/carbon material protected by silicon carbide (SiC) and a glass coating. The glass coating is known as Type A and is primarily sodium silicate with particles of SiC. NASA Glenn Research Center's Environmental Durability Branch was asked to determine the chemistry of this deposit formation and assess any possible detrimental effects. At low temperatures, the reverse reaction is favorable. Previous studies of the corrosion of glass show that carbon dioxide in the presence of water does form sodium carbonate on sodium silicate glass (ref. 1). It is quite likely that a similar scenario exists for the orbiter wing leading edge. All three orbiters that formed sodium carbonate were exposed to rain. This formation of sodium carbonate was duplicated in the laboratory. The Type A glass, which coats the wing leading edge and nose cap, was made in a freestanding form and exposed to water in two separate experiments. In one set of experiments, the coating was placed in a petri dish filled with water. As the water evaporated, sodium carbonate formed. In another case, water was slowly dripped on the coating and sodium carbonate formed. The sodium carbonate was detected by chemical analysis and, in some cases, xray diffraction showed a hydrated sodium carbonate. The next step was to examine possible detrimental effects of this sodium carbonate. There are three likely scenarios for the sodium carbonate deposit: (1) it may be removed with a simple rinse, (2) it may remain and flow back into the Type A glass after heating during reentry, or (3) it may remain and flow onto unprotected SiC and/or other parts after heating during reentry. The effect of case 1 is to remove the Na2O constituent from the Type A glass, thus decreasing its effectiveness as a sealant. Even so, overall, it is probably the best

  16. Studies Conducted of Sodium Carbonate Contaminant Found on the Wing Leading Edge and the Nose Cap of the Space Shuttle Orbiter

    NASA Technical Reports Server (NTRS)

    Jacobson, Nathan S.; Palou, Jaime J.

    2003-01-01

    In early 2001, three of the space shuttle orbiters were found to have a sodium carbonate contaminant on the wing leading edge and nose cap. These parts are made of a reinforced carbon/carbon material protected by silicon carbide (SiC) and a glass coating. The glass coating is known as Type A and is primarily sodium silicate with particles of SiC. NASA Glenn Research Center's Environmental Durability Branch was asked to determine the chemistry of this deposit formation and assess any possible detrimental effects. At low temperatures, the reverse reaction is favorable. Previous studies of the corrosion of glass show that carbon dioxide in the presence of water does form sodium carbonate on sodium silicate glass (ref. 1). It is quite likely that a similar scenario exists for the orbiter wing leading edge. All three orbiters that formed sodium carbonate were exposed to rain. This formation of sodium carbonate was duplicated in the laboratory. The Type A glass, which coats the wing leading edge and nose cap, was made in a freestanding form and exposed to water in two separate experiments. In one set of experiments, the coating was placed in a petri dish filled with water. As the water evaporated, sodium carbonate formed. In another case, water was slowly dripped on the coating and sodium carbonate formed. The sodium carbonate was detected by chemical analysis and, in some cases, xray diffraction showed a hydrated sodium carbonate. The next step was to examine possible detrimental effects of this sodium carbonate. There are three likely scenarios for the sodium carbonate deposit: (1) it may be removed with a simple rinse, (2) it may remain and flow back into the Type A glass after heating during reentry, or (3) it may remain and flow onto unprotected SiC and/or other parts after heating during reentry. The effect of case 1 is to remove the Na2O constituent from the Type A glass, thus decreasing its effectiveness as a sealant. Even so, overall, it is probably the best

  17. Beneficial effects of activated carbon additives on the performance of negative lead-acid battery electrode for high-rate partial-state-of-charge operation

    NASA Astrophysics Data System (ADS)

    Xiang, Jiayuan; Ding, Ping; Zhang, Hao; Wu, Xianzhang; Chen, Jian; Yang, Yusheng

    2013-11-01

    Experiments are made with negative electrode of 2 V cell and 12 V lead-acid battery doped with typical activated carbon additives. It turns out that the negative electrode containing tens-of-micron-sized carbon particles in NAM exhibits markedly increased HRPSoC cycle life than the one containing carbon particles with much smaller size of several microns or the one containing no activated carbon. The improved performance is mainly attributed to the optimized NAM microstructure and the enhanced electrode reaction kinetics by introducing appropriate activated carbon. The beneficial effects can be briefly summarized from three aspects. First, activated carbon acts as new porous-skeleton builder to increase the porosity and active surface of NAM, and thus facilitates the electrolyte diffusion from surface to inner and provides more sites for crystallization/dissolution of lead sulfate; second, activated carbon plays the role of electrolyte supplier to provide sufficient H2SO4 in the inner of plate when the diffusion of H2SO4 from plate surface cannot keep pace of the electrode reaction; Third, activated carbon acts as capacitive buffer to absorb excess charge current which would otherwise lead to insufficient NAM conversion and hydrogen evolution.

  18. Nanostructuring effect of multi-walled carbon nanotubes on electrochemical properties of carbon foam as constructive electrode for lead acid battery

    NASA Astrophysics Data System (ADS)

    Kumar, Rajeev; Kumari, Saroj; Mathur, Rakesh B.; Dhakate, Sanjay R.

    2015-01-01

    In the present study, nanostructuring effect of multi-walled carbon nanotubes (MWCNTs) on electrochemical properties of coal tar pitch (CTP) based carbon foam (CFoam) was investigated. The different weight fractions of MWCNTs were mixed with CTP and foam was developed from the mixture of CTP and MWCNTs by sacrificial template technique and heat treated at 1,400 and 2,500 °C in inert atmosphere. These foams were characterized by scanning electron microscopy, X-ray diffraction, and potentiostat PARSTAT for cyclic voltammetry. It was observed that, bulk density of CFoam increases with increasing MWCNTs content and decreases after certain amount. The MWCNTs influence the morphology of CFoam and increase the width of ligaments as well as surface area. During the heat treatment, stresses exerting at MWCNTs/carbon interface accelerate ordering of the graphene layer which have positive effect on the electrochemical properties of CFoam. The current density increases from 475 to 675 mA/cm2 of 1,400 °C heat treated and 95 to 210 mA/cm2 of 2,500 °C heat-treated CFoam with 1 wt% MWCNTs. The specific capacitance was decreases with increasing the scan rate from 100 to 1,000 mV/s. In case of 1 % MWCNTs content CFoam the specific capacitance at the scan rate 100 mV/s was increased from 850 to 1,250 μF/cm2 and 48 to 340 μF/cm2 of CFoam heat treated at 1,400 °C and 2,500 °C respectively. Thus, the higher value surface area and current density of MWCNTs-incorporated CFoam heat treated to 1,400 °C can be suitable for lead acid battery electrode with improved charging capability.

  19. Tree Death Leading To Ecosystem Renewal? Forecasting Carbon Storage As Eastern Forests Age

    NASA Astrophysics Data System (ADS)

    Curtis, P.; Gough, C. M.; Bohrer, G.; Nadelhoffer, K. J.; Ivanov, V. Y.

    2013-12-01

    The future trajectory of North American carbon (C) stocks remains uncertain as a subset of maturing trees die in mixed deciduous forests of the U.S. Midwest and East transitioning from early to middle and late succession. We are studying disturbance-structure-function relationships of aging forests in northern Michigan using long-term ecological and meteorological C cycling studies, a large-scale disturbance experiment, a 200-year forest chronosequence, and flux comparisons across three tower sites. We find that ecosystem responses to mortality are characterized by several processes that affect structure-function relationships and alter the way ecosystem functioning interacts with meteorological forcing. We subjected 39 ha of forest to moderate experimental disturbance, similar to that of age-related or climatically induced tree mortality. We found that the mortality of a third of all canopy trees minimally altered the balance between forest C uptake and release, as growth-limiting light and nitrogen resources were rapidly reallocated from dead and dying trees to undisturbed trees. Although disturbance-induced mortality increased soil N mineralization rates, nitrification, and denitrification, N exports from soils remained low. Upper canopy gap formation and a rise in structural complexity allowed increased photosynthetic contribution of sub-canopy vegetation to compensate for the death of canopy dominant trees. However, we found large differences between the transpirational response of maples and oaks to VPD and soil moisture, which led to relative declines in maple transpiration post-disturbance. These hydrologic differences may affect a species' ability to compete for resources following such a disturbance. Changes to canopy structure had a relatively small effect on roughness length and the turbulence forcing of fluxes from the canopy. We currently are studying how tree mortality driven changes in canopy structure affects within-canopy resource distribution and

  20. Neutron production in collisions between carbon nuclei of energy 2 GeV per nucleon and carbon, aluminum, copper, cadmium, and lead nuclei

    SciTech Connect

    Yurevich, V. I.; Yakovlev, R. M.; Lyapin, V. G.

    2012-02-15

    Double-differential cross sections for neutron production were measured by the time-of-flight method for the interactions between carbon nuclei of energy 2 GeV per nucleon and carbon, aluminum, copper, cadmium, and lead nuclei. These measurements were performed for angles of 30 Degree-Sign , 53 Degree-Sign , and 90 Degree-Sign in the neutron-energy range fromseveral hundred keVunits to 300MeV. The phenomenologicalmodel of four moving sources was used as a basis in analyzing experimental results and in estimating the contribution to neutron emission from various reaction stages. The temperature parameters determined from the slope of the neutron energy spectra proved to be 22 {+-} 2 MeV for a hot source (fireball) and 4.5 {+-} 0.3 MeV for the stage of thermal fragmentation of highly excited heavy nuclear residues. The relative contribution of these two sources to the total neutron yield is independent of the type of the target nucleus and is about 42%, on average.

  1. Carbon nanotubes allow capture of krypton, barium and lead for multichannel biological X-ray fluorescence imaging

    PubMed Central

    Serpell, Christopher J.; Rutte, Reida N.; Geraki, Kalotina; Pach, Elzbieta; Martincic, Markus; Kierkowicz, Magdalena; De Munari, Sonia; Wals, Kim; Raj, Ritu; Ballesteros, Belén; Tobias, Gerard; Anthony, Daniel C.; Davis, Benjamin G.

    2016-01-01

    The desire to study biology in situ has been aided by many imaging techniques. Among these, X-ray fluorescence (XRF) mapping permits observation of elemental distributions in a multichannel manner. However, XRF imaging is underused, in part, because of the difficulty in interpreting maps without an underlying cellular ‘blueprint'; this could be supplied using contrast agents. Carbon nanotubes (CNTs) can be filled with a wide range of inorganic materials, and thus can be used as ‘contrast agents' if biologically absent elements are encapsulated. Here we show that sealed single-walled CNTs filled with lead, barium and even krypton can be produced, and externally decorated with peptides to provide affinity for sub-cellular targets. The agents are able to highlight specific organelles in multiplexed XRF mapping, and are, in principle, a general and versatile tool for this, and other modes of biological imaging. PMID:27782209

  2. Carbon nanotubes allow capture of krypton, barium and lead for multichannel biological X-ray fluorescence imaging.

    PubMed

    Serpell, Christopher J; Rutte, Reida N; Geraki, Kalotina; Pach, Elzbieta; Martincic, Markus; Kierkowicz, Magdalena; De Munari, Sonia; Wals, Kim; Raj, Ritu; Ballesteros, Belén; Tobias, Gerard; Anthony, Daniel C; Davis, Benjamin G

    2016-10-26

    The desire to study biology in situ has been aided by many imaging techniques. Among these, X-ray fluorescence (XRF) mapping permits observation of elemental distributions in a multichannel manner. However, XRF imaging is underused, in part, because of the difficulty in interpreting maps without an underlying cellular 'blueprint'; this could be supplied using contrast agents. Carbon nanotubes (CNTs) can be filled with a wide range of inorganic materials, and thus can be used as 'contrast agents' if biologically absent elements are encapsulated. Here we show that sealed single-walled CNTs filled with lead, barium and even krypton can be produced, and externally decorated with peptides to provide affinity for sub-cellular targets. The agents are able to highlight specific organelles in multiplexed XRF mapping, and are, in principle, a general and versatile tool for this, and other modes of biological imaging.

  3. Carbon nanotubes allow capture of krypton, barium and lead for multichannel biological X-ray fluorescence imaging

    NASA Astrophysics Data System (ADS)

    Serpell, Christopher J.; Rutte, Reida N.; Geraki, Kalotina; Pach, Elzbieta; Martincic, Markus; Kierkowicz, Magdalena; de Munari, Sonia; Wals, Kim; Raj, Ritu; Ballesteros, Belén; Tobias, Gerard; Anthony, Daniel C.; Davis, Benjamin G.

    2016-10-01

    The desire to study biology in situ has been aided by many imaging techniques. Among these, X-ray fluorescence (XRF) mapping permits observation of elemental distributions in a multichannel manner. However, XRF imaging is underused, in part, because of the difficulty in interpreting maps without an underlying cellular `blueprint' this could be supplied using contrast agents. Carbon nanotubes (CNTs) can be filled with a wide range of inorganic materials, and thus can be used as `contrast agents' if biologically absent elements are encapsulated. Here we show that sealed single-walled CNTs filled with lead, barium and even krypton can be produced, and externally decorated with peptides to provide affinity for sub-cellular targets. The agents are able to highlight specific organelles in multiplexed XRF mapping, and are, in principle, a general and versatile tool for this, and other modes of biological imaging.

  4. Characterization of lead (Ⅱ)-containing activated carbon and its excellent performance of extending lead-acid battery cycle life for high-rate partial-state-of-charge operation

    NASA Astrophysics Data System (ADS)

    Tong, Pengyang; Zhao, Ruirui; Zhang, Rongbo; Yi, Fenyun; Shi, Guang; Li, Aiju; Chen, Hongyu

    2015-07-01

    In this work, lead (Ⅱ)-containing activated carbon (Pb@C) is prepared as the additive of negative active mass (NAM), aiming to enhance the electrochemical characteristics of the lead-acid battery. The characters of the Pb@C materials and their electrochemical properties are characterized by XRD, SEM, back-scattering electron image (BESI) and electrochemical methods. The lead (Ⅱ) ions disperse well in the carbon bulk of the obtained Pb@C materials as observed, and these materials exhibit remarkable higher specific capacitance and higher hydrogen evolution over-potential compared with original carbons. Many 2 V lead-acid batteries are assembled manually in our lab, and then the batteries are disassembled after formation and high-rate-partial-state-of-charge (HRPSoC) cycling. Results manifest that the Pb@C additives exhibit high affinity to lead and act as a porous-skeleton in the formation process as well as under HRPSoC cycling conditions, leading to the small and fine formation of PbSO4 particles and accordingly higher active material utilization rate more than 50%, better cycling performance and charging acceptance. Besides, excellent cycle performances of these batteries have great relationship with the dazzling hydrogen evolution performance of Pb@C materials. A possible working mechanism is also proposed based on the testing data in this paper.

  5. Effects of coulomb repulsion on conductivity of heterojunction carbon nanotube quantum dots with spin-orbital coupling and interacting leads

    NASA Astrophysics Data System (ADS)

    Ogloblya, O. V.; Kuznietsova, H. M.; Strzhemechny, Y. M.

    2017-01-01

    We performed numerical studies for the conductance of a heterojunction carbon nanotube quantum dot (QD) with an extra spin orbital quantum number and a conventional QD in which the electron state is determined only by the spin quantum number. Our computational approach took into account the spin-orbit interaction and the Coulomb repulsion both between electrons on a QD as well as between the QD electron and the contacts. We utilized an approach based on the Keldysh non-equilibrium Green's function formalism as well as the equation of motion technique. We focused on the case of a finite Coulombic on-site repulsion and considered two possible cases of applied voltage: spin bias and conventional bias. For the system of interest we obtained bias spectroscopy diagrams, i.e. contour charts showing dependence of conductivity on two variables - voltage and the energy level position in a QD - which can be controlled by the plunger gate voltage. The finite Coulombic repulsion splits the density of states into two distinct maxima with the energy separation between them controlled by that parameter. It was also shown that an increase of either the value of the on-site Coulomb repulsion in a QD or the parameter of the Coulomb repulsion between the electrons in the QD and the contacts leads to an overall shift of the density of electronic states dependence toward higher energy values. Presence of the QD-lead interaction yields formation of a new pair of peaks in the differential conductance dependence. We also show that existence of four quantum states in a QD leads to abrupt changes in the density of states. These results could be beneficial for potential applications in nanotube-based amperometric sensors.

  6. Lead sensors development and antimicrobial activities based on graphene oxide/carbon nanotube/poly(O-toluidine) nanocomposite.

    PubMed

    Khan, Aftab Aslam Parwaz; Khan, Anish; Rahman, Mohammed M; Asiri, Abdullah M; Oves, Mohammad

    2016-08-01

    Graphene oxide/carbon nanotube/poly (O-toluidine) (GO-CNT-POT) nanocomposite was prepared by a situ polymerization method and characterized by X-ray powder diffractometry (XRD) and scanning electron microscopy (SEM). The antibacterial activity of the obtained GO-CNT-POT nanocomposite was also evaluated against Gram positive bacteria Bacillus subtilis, Gram negative bacteria Escherichia coli and antibiotics (Amoxicillin) using the agar plate. The antibacterial study showed that the GO-CNT-POT was found to be most effective against both B. subtilis and E. coli respectively which was significant compared to the amoxicillin and the simultaneously GO-CNT-POT nanocomposite were fabricated onto glassy carbon electrode (GCE) using conducting coating binders by I-V technique, where the total analytical parameters were measured for the development of sensitive lead sensors (Pb(2+)). The GO-CNT-POT nanocomposite were deposited on flat-GCE (surface area: ∼0.0316cm(2)) to result in a sensor that has a fast response to selective Pb(2+) ions in buffer system. Features including sensitivity, detection limit, reproducibility, linear dynamic range, selectivity, and electrochemical performances were investigated in details with the GO-CNT-POT nanocomposite fabricated GCE electrodes. The calibration plot is linear (r(2): 0.9907) over the large concentration range (0.1nM to 1.0mM). The sensitivity and detection limit is calculated as 8.53164μAcm(-2)μM(-1) and 89.0 pM (at a signal-to-noise-ratio, SNR of 3) respectively. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. Effects of copper, lead, and cadmium on the sorption and desorption of atrazine onto and from carbon nanotubes.

    PubMed

    Chen, Guang-Cai; Shan, Xiao-Quan; Wang, Yu-Sheng; Pei, Zhi-Guo; Shen, Xiu-E; Wen, Bei; Owens, Gary

    2008-11-15

    There are currently few studies on the dual effects of metal ions on the sorption of atrazine and conversely of atrazine on metal adsorption on multiwalled carbon nanotubes (MWCNTs). While a number of sorption models were considered to describe the sorption of atrazine on MWCNTs, the Polanyi-Manes model (PMM) fit the sorption isotherms well with the lowest mean weighted square errors. Atrazine was mainly adsorbed onto the surface and micropores of MWCNTs bundles or aggregates. Hydrogen bonding between azo and amino nitrogen of atrazine and functional groups on MWCNTs also occurred. Oxygenated functionalities, mainly carboxylic groups on MWCNTs surface, decreased the sorption of atrazine. Metal cations Cu2+, Pb2+, and Cd2+ diminished the sorption of atrazine depending on the oxygenated functionalities densities. The mechanisms ascribed were due to the formation of surface or inner-sphere complexes of Cu2+, Pb2+, and Cd2+ through carboxylic groups and hydration, which may occupy part of the surface of MWCNTs-O. The large hydration shell of metal cations may intrude or shield the hydrophobic and hydrophilic sites and indirectly compete with atrazine for surface sites, leading to the inhibition of atrazine adsorption around the metal-complexed moieties.

  8. Black Carbon, Metal Concentrations and Lead Isotopes Ratios in Aerosols as Tracers of Human and Natural Activities in Northern Vietnam

    NASA Astrophysics Data System (ADS)

    Guinot, B. P.

    2015-12-01

    Atmospheric brown clouds (ABC) observed as widespread layers of brownish haze are regional scale plumes of air pollutants with a hot spot of emission located in East Asia. ABC are mainly composed of aerosol particles such as Black Carbon (BC) emitted to the atmosphere during biomass burning and fossil fuels combustion. The atmospheric lifetime of BC ranges from a few days in wet season up to one month in dry season. The use of stable lead isotopes and 21 elements as tracers of air pollution was applied to identify and characterized the main sources of anthropogenic activities in Asian region. Aerosol samples from Haiphong (North Vietnam) were collected by a high volume sampler for a period of one year from October 2012 to October 2013. Vietnam's 207Pb/206Pb ratios were almost identical to those found for China. Ratios of 207Pb/206Pb ranged from 0.837 to 0.871 which agrees with values previously reported for the last 10 years in China (0.841 - 0.879). No significant variation in isotope ratio was observed during the sampling period, which suggests that there was no large seasonal variation in the isotope ratios of airborne lead. Trajectory analysis showed that almost two third of the air masses originated from East Northeast which implies that China was a major source of lead in atmosphere. Enrichment factor calculations indicated a large influence of coal activity (EF(Al) As = 1982 ± 796, EF(Al) Cd = 972 ± 659, EF(Al) Sb = 1358 ± 930) but the difference between combustion and mining exploitation could not be evidenced. Significant correlations were found between two others groups of elements: As, Cu, Ni, Zn, and Al, Fe K, Co. Wind dilution was effective on metals concentration variation. During the cold and dry season (winter) ambient concentrations were high and variable, during the warm and wet season (summer) concentrations were stable and low. Taken together, these factors also identified industrial and lithogenic activities in the region.

  9. Application of polypyrrole multi-walled carbon nanotube composite layer for detection of mercury, lead and iron ions using surface plasmon resonance technique.

    PubMed

    Sadrolhosseini, Amir Reza; Noor, A S M; Bahrami, Afarin; Lim, H N; Talib, Zainal Abidin; Mahdi, Mohd Adzir

    2014-01-01

    Polypyrrole multi-walled carbon nanotube composite layers were used to modify the gold layer to measure heavy metal ions using the surface plasmon resonance technique. The new sensor was fabricated to detect trace amounts of mercury (Hg), lead (Pb), and iron (Fe) ions. In the present research, the sensitivity of a polypyrrole multi-walled carbon nanotube composite layer and a polypyrrole layer were compared. The application of polypyrrole multi-walled carbon nanotubes enhanced the sensitivity and accuracy of the sensor for detecting ions in an aqueous solution due to the binding of mercury, lead, and iron ions to the sensing layer. The Hg ion bonded to the sensing layer more strongly than did the Pb and Fe ions. The limitation of the sensor was calculated to be about 0.1 ppm, which produced an angle shift in the region of 0.3° to 0.6°.

  10. Application of Polypyrrole Multi-Walled Carbon Nanotube Composite Layer for Detection of Mercury, Lead and Iron Ions Using Surface Plasmon Resonance Technique

    PubMed Central

    Sadrolhosseini, Amir Reza; Noor, A. S. M.; Bahrami, Afarin; Lim, H. N.; Talib, Zainal Abidin; Mahdi, Mohd. Adzir

    2014-01-01

    Polypyrrole multi-walled carbon nanotube composite layers were used to modify the gold layer to measure heavy metal ions using the surface plasmon resonance technique. The new sensor was fabricated to detect trace amounts of mercury (Hg), lead (Pb), and iron (Fe) ions. In the present research, the sensitivity of a polypyrrole multi-walled carbon nanotube composite layer and a polypyrrole layer were compared. The application of polypyrrole multi-walled carbon nanotubes enhanced the sensitivity and accuracy of the sensor for detecting ions in an aqueous solution due to the binding of mercury, lead, and iron ions to the sensing layer. The Hg ion bonded to the sensing layer more strongly than did the Pb and Fe ions. The limitation of the sensor was calculated to be about 0.1 ppm, which produced an angle shift in the region of 0.3° to 0.6°. PMID:24733263

  11. Enhanced performance of starter lighting ignition type lead-acid batteries with carbon nanotubes as an additive to the active mass

    NASA Astrophysics Data System (ADS)

    Marom, Rotem; Ziv, Baruch; Banerjee, Anjan; Cahana, Beni; Luski, Shalom; Aurbach, Doron

    2015-11-01

    Addition of various carbon materials into lead-acid battery electrodes was studied and examined in order to enhance the power density, improve cycle life and stability of both negative and positive electrodes in lead acid batteries. High electrical-conductivity, high-aspect ratio, good mechanical properties and chemical stability of multi-wall carbon nanotubes (MWCNT, unmodified and mofified with carboxylic groups) position them as viable additives to enhance the electrodes' electrical conductivity, to mitigate the well-known sulfation failure mechanism and improve the physical integration of the electrodes. In this study, we investigated the incorporation-effect of carbon nanotubes (CNT) to the positive and the negative active materials in lead-acid battery prototypes in a configuration of flooded cells, as well as gelled cells. The cells were tested at 25% and 30% depth-of-discharge (DOD). The positive effect of the carbon nanotubes (CNT) utilization as additives to both positive and negative electrodes of lead-acid batteries was clearly demonstrated and is explained herein based on microscopic studies.

  12. Batch sorption dynamics and equilibrium for the removal of lead ions from aqueous phase using activated carbon developed from coffee residue activated with zinc chloride.

    PubMed

    Boudrahem, F; Aissani-Benissad, F; Aït-Amar, H

    2009-07-01

    Lignocellulosic materials are good precursors for the production of activated carbon. In this work, coffee residue has been used as raw material in the preparation of powder activated carbon by the method of chemical activation with zinc chloride for the sorption of Pb(II) from dilute aqueous solutions. The influence of impregnation ratio (ZnCl2/coffee residue) on the physical and chemical properties of the prepared carbons was studied in order to optimize this parameter. The optimum experimental condition for preparing predominantly microporous activated carbons with high pore surface area (890 m2/g) and micropore volume (0.772 cm3/g) is an impregnation ratio of 100%. The developed activated carbon shows substantial capability to sorb lead(II) ions from aqueous solutions and for relative impregnation ratios of 75 and 100%, the maximum uptake is practically the same. Thus, 75% represents the optimal impregnation ratio. Batch experiments were conducted to study the effects of the main parameters such as contact time, initial concentration of Pb(II), solution pH, ionic strength and temperature. The maximum uptake of lead(II) at 25 degrees C was about 63 mg/g of adsorbent at pH 5.8, initial Pb(II) concentration of 10 mg/L, agitation speed of 200 rpm and ionic strength of 0.005 M. The kinetic data were fitted to the models of pseudo-first order and pseudo-second order, and follow closely the pseudo-second order model. Equilibrium sorption isotherms of Pb(II) were analyzed by the Langmuir, Freundlich and Temkin isotherm models. The Freundlich model gives a better fit than the others. Results from this study suggest that activated carbon produced from coffee residue is an effective adsorbent for the removal of lead from aqueous solutions and that ZnCl2 is a suitable activating agent for the preparation of high-porosity carbons.

  13. Synthesis of fluorescent carbon dots via simple acid hydrolysis of bovine serum albumin and its potential as sensitive sensing probe for lead (II) ions.

    PubMed

    Wee, Shui Shui; Ng, Yann Huey; Ng, Sing Muk

    2013-11-15

    Carbon dots have great potential to be utilised as an optical sensing probe due to its unique photoluminescence and less toxic properties. This work reports a simple and novel synthesis method of carbon dots via direct acid hydrolysis of bovine serum albumin protein in a one-pot approach. Optimisation of the important synthetic parameters has been performed which consists of temperature effect, acid to protein ratio and kinetics of reaction. Higher temperature has promoted better yield with shorter reaction time. The carbon dots obtained shows a strong emission at the wavelength of 400 nm with an optimum excitation of 305 nm. The potential of the carbon dots as optical sensing probe has been investigated on with different cations that are of environmental and health concern. The fluorescence of the carbon dots was significantly quenched particularly by lead (II) ions in a selective manner. Further analytical study has been performed to leverage the performance of the carbon dots for lead (II) ions sensing using the standard Stern-Volmer relationship. The sensing probe has a dynamic linear range up to 6.0 mM with a Stern-Volmer constant of 605.99 M(-1) and a limit of detection (LOD) of 5.05 μM. The probe performance was highly repeatable with a standard deviation below 3.0%. The probe suggested in this study demonstrates the potential of a more economical and greener approach that uses protein based carbon dots for sensing of heavy metal ions. Copyright © 2013 Elsevier B.V. All rights reserved.

  14. 4.4.5 R1: Alkyl or substituted alkyl; R2: Carbon centered functional group; R3: Leading atom other than carbon

    NASA Astrophysics Data System (ADS)

    Beckwith, A. L. J.

    This document is part of Subvolume A1 `Inorganic Radicals, Metal Complexes and Nonconjugated Carbon Centered Radicals' of Volume 26 `Magnetic Properties of Free Radicals' of Landolt-Börnstein Group II `Molecules and Radicals'.

  15. 4.4.3 R1 and R2: Alkyl or substituted alkyl; R3: Leading atom other than carbon

    NASA Astrophysics Data System (ADS)

    Beckwith, A. L. J.

    This document is part of Subvolume A1 `Inorganic Radicals, Metal Complexes and Nonconjugated Carbon Centered Radicals' of Volume 26 `Magnetic Properties of Free Radicals' of Landolt-Börnstein Group II `Molecules and Radicals'.

  16. Carbon sequestration in croplands is mainly driven by management leading to increased net primary production - evidence from long-term field experiments in Northern Europe

    NASA Astrophysics Data System (ADS)

    Kätterer, Thomas; Bolinder, Martin Anders; Börjesson, Gunnar; Kirchmann, Holger; Poeplau, Christopher

    2014-05-01

    carbon stocks not always lead to net sequestration of atmospheric CO2 and that C sequestration not always leads to mitigation of greenhouse gas emissions. The consequences of different land use and management are discussed, taking into account two critical boundaries - the limited area of agricultural land on Earth and requirements to produce sufficient food, fibres and energy for a growing population.

  17. Characterization and lead adsorption properties of activated carbons prepared from cotton stalk by one-step H3PO4 activation.

    PubMed

    Li, Kunquan; Zheng, Zheng; Li, Ye

    2010-09-15

    Activated carbons were prepared from cotton stalk by one-step H(3)PO(4) activation and used as adsorbent for the removal of lead(II). Taguchi experimental design method was used to optimize the preparation of the adsorbents. The results showed that the optimized conditions were: impregnation with a 50% (w/v) phosphoric acid solution with a mass ratio of 3:2 and activation temperature at 500 degrees C for 60 min with the rate of achieving the activation temperature equal to 10 degrees C min(-1). The cotton stalk activated carbon (CSAC) prepared at these conditions have 1.43 mmol g(-1) acidic surface groups and 1570 m(2) g(-1) BET surface area. Adsorption isotherms for lead(II) on the adsorbents were measured by conducting a series of batch adsorption experiments. The Langmuir maximum adsorption amount of lead(II) on CSAC was more than 119 mg g(-1), which was superior to the ordinary commercial activated carbon (CAC) on the market. Compared with the CAC, the CSAC had a wider applicable pH range from 3.5 to 6.5 for lead(II) uptake. The final pH values at equilibrium after adsorption were lower than the initial pH value, indicating that the ion-exchange process was involved in the adsorption. This is also confirmed by the result that the increase of acidic surface groups favored the adsorption process. Thermodynamic study indicated that the adsorption was a spontaneous and endothermic process.

  18. Mussel-Inspired Dopamine and Carbon Nanotube Leading to a Biocompatible Self-Rolling Conductive Hydrogel Film

    PubMed Central

    Jiang, Junzi; Huang, Yong; Wang, Yitian; Xu, Hui; Xing, Malcolm; Zhong, Wen

    2017-01-01

    We report a novel self-rolling, conductive, and biocompatible multiwall carbon nanotube (MWCNT)-dopamine-polyethylene glycol (PEG) hydrogel film. The gel can self-fold into a thin tube when it is transferred from a glass slide to an aqueous environment, regardless of the concentrations of the MWCNT. The film presents a highly organized pattern, which results from the self-assembly of hydrophilic dopamine and hydrophobic carbon nanotubes. By exploring the biomedical potential, we found that MWCNT-included rolled film is nontoxic and can promote cell growth. For further functional verification by qPCR (quantitative polymerase chain reaction), bone marrow derived mesenchymal cells present higher levels of osteogenic differentiations in response to a higher concentration of CNTs. The results suggest that the self-rolling, conductive CNT-dopamine-PEG hydrogel could have multiple potentials, including biomedical usage and as a conductive biosensor. PMID:28820472

  19. Removal of lead from aqueous solution by activated carbon prepared from Enteromorpha prolifera by zinc chloride activation.

    PubMed

    Li, Yanhui; Du, Qiuju; Wang, Xiaodong; Zhang, Pan; Wang, Dechang; Wang, Zonghua; Xia, Yanzhi

    2010-11-15

    Activated carbon was prepared from Enteromorpha prolifera (EP) by zinc chloride activation. The physico-chemical properties of EP-activated carbon (EPAC) were characterized by thermal stability, zeta potential and Boehm titration methods. The examination showed that EPAC has a porous structure with a high surface area of 1688 m(2)/g. Batch adsorption experiments were carried out to study the effect of various parameters such as initial pH, adsorbent dosage, contact time and temperature on Pb(II) ions adsorption properties by EPAC. The kinetic studies showed that the adsorption data followed a pseudo second-order kinetic model. The isotherm analysis indicated that the adsorption data can be represented by Freundlich isotherm model. Thermodynamic studies indicated that the adsorption reaction was a spontaneous and endothermic process.

  20. Mussel-Inspired Dopamine and Carbon Nanotube Leading to a Biocompatible Self-Rolling Conductive Hydrogel Film.

    PubMed

    Jiang, Junzi; Huang, Yong; Wang, Yitian; Xu, Hui; Xing, Malcolm; Zhong, Wen

    2017-08-18

    We report a novel self-rolling, conductive, and biocompatible multiwall carbon nanotube (MWCNT)-dopamine-polyethylene glycol (PEG) hydrogel film. The gel can self-fold into a thin tube when it is transferred from a glass slide to an aqueous environment, regardless of the concentrations of the MWCNT. The film presents a highly organized pattern, which results from the self-assembly of hydrophilic dopamine and hydrophobic carbon nanotubes. By exploring the biomedical potential, we found that MWCNT-included rolled film is nontoxic and can promote cell growth. For further functional verification by qPCR (quantitative polymerase chain reaction), bone marrow derived mesenchymal cells present higher levels of osteogenic differentiations in response to a higher concentration of CNTs. The results suggest that the self-rolling, conductive CNT-dopamine-PEG hydrogel could have multiple potentials, including biomedical usage and as a conductive biosensor.

  1. Electrochemical response of carbon paste electrode modified with mixture of titanium dioxide/zirconium dioxide in the detection of heavy metals: lead and cadmium.

    PubMed

    Nguyen, Phuong Khanh Quoc; Lunsford, Suzanne K

    2012-11-15

    A novel carbon modified electrode was developed by incorporating titanium dioxide/zirconium dioxide into the graphite carbon paste electrode to detect heavy metals-cadmium and lead. In this work, the development of the novel titanium dioxide/zirconium dioxide modified carbon paste electrode was studied to determine the optimum synthesis conditions related to the temperature, heating duration, amount and ratio of titanium dioxide/zirconium dioxide, and amount of surfactant, to create the most reproducible results. Using cyclic voltammetric (CV) analysis, this study has proven that the novel titanium dioxide/zirconium dioxide can be utilized to detect heavy metals-lead and cadmium, at relatively low concentrations (7.6×10(-6) M and 1.1×10(-5) M for Pb and Cd, respectively) at optimum pH value (pH=3). From analyzing CV data the optimal electrodes surface area was estimated to be 0.028 (±0.003) cm(2). Also, under the specific experimental conditions, electron transfer coefficients were estimated to be 0.44 and 0.33 along with the heterogeneous electron transfer rate constants of 5.64×10(-3) and 2.42×10(-3) (cm/s) for Pb and Cd, respectively. Copyright © 2012 Elsevier B.V. All rights reserved.

  2. Organic carbon and reducing conditions lead to cadmium immobilization by secondary Fe mineral formation in a pH-neutral soil.

    PubMed

    Muehe, E Marie; Adaktylou, Irini J; Obst, Martin; Zeitvogel, Fabian; Behrens, Sebastian; Planer-Friedrich, Britta; Kraemer, Ute; Kappler, Andreas

    2013-01-01

    Cadmium (Cd) is of environmental relevance as it enters soils via Cd-containing phosphate fertilizers and endangers human health when taken up by crops. Cd is known to associate with Fe(III) (oxyhydr)oxides in pH-neutral to slightly acidic soils, though it is not well understood how the interrelation of Fe and Cd changes under Fe(III)-reducing conditions. Therefore, we investigated how the mobility of Cd changes when a Cd-bearing soil is faced with organic carbon input and reducing conditions. Using fatty acid profiles and quantitative PCR, we found that both fermenting and Fe(III)-reducing bacteria were stimulated by organic carbon-rich conditions, leading to significant Fe(III) reduction. The reduction of Fe(III) minerals was accompanied by increasing soil pH, increasing dissolved inorganic carbon, and decreasing Cd mobility. SEM-EDX mapping of soil particles showed that a minor fraction of Cd was transferred to Ca- and S-bearing minerals, probably carbonates and sulfides. Most of the Cd, however, correlated with a secondary iron mineral phase that was formed during microbial Fe(III) mineral reduction and contained mostly Fe, suggesting an iron oxide mineral such as magnetite (Fe3O4). Our data thus provide evidence that secondary Fe(II) and Fe(II)/Fe(III) mixed minerals could be a sink for Cd in soils under reducing conditions, thus decreasing the mobility of Cd in the soil.

  3. Basanite-nephelinite suite from early Kilauea: Carbonated melts of phlogopite-garnet peridotite at Hawaii's leading magmatic edge

    USGS Publications Warehouse

    Sisson, T.W.; Kimura, Jun-Ichi; Coombs, M.L.

    2009-01-01

    A basanite-nephelinite glass suite from early submarine Kilauea defines a continuous compositional array marked by increasing concentrations of incompatible components with decreasing SiO2, MgO, and Al2O3. Like peripheral and post-shield strongly alkalic Hawaiian localities (Clague et al. in J Volcanol Geotherm Res 151:279-307, 2006; Dixon et al. in J Pet 38:911-939, 1997), the early Kilauea basanite-nephelinite glasses are interpreted as olivine fractionation products from primary magnesian alkalic liquids. For early Kilauea, these were saturated with a garnet-phlogopite-sulfide peridotite assemblage, with elevated dissolved CO2 contents responsible for the liquids' distinctly low-SiO2 concentrations. Reconstructed primitive liquids for early Kilauea and other Hawaiian strongly alkalic localities are similar to experimental 3 GPa low-degree melts of moderately carbonated garnet lherzolite, and estimated parent magma temperatures of 1,350-1,400??C (olivine-liquid geothermometry) match the ambient upper mantle geotherm shortly beneath the base of the lithosphere. The ???3 GPa source regions were too hot for stable crystalline carbonate and may have consisted of ambient upper mantle peridotite containing interstitial carbonate-silicate or carbonatitic liquid, possibly (Dixon et al. in Geochem Geophys Geosyst 9(9):Q09005, 2008), although not necessarily, from the Hawaiian mantle plume. Carbonate-enriched domains were particularly susceptible to further melting upon modest decompression during upward lithospheric flexure beneath the advancing Hawaiian Arch, or by conductive heating or upward drag by the Hawaiian mantle plume. The early Kilauea basanite-nephelinite suite has a HIMU-influenced isotopic character unlike other Hawaiian magmas (Shimizu et al. in EOS Tran Amer Geophys Union 82(47): abstr V12B-0962, 2001; Shimizu et al. in Geochim Cosmochim Acta 66(15A):710, 2002) but consistent with oceanic carbonatite involvement (Hoernle et al. in Contrib Mineral Petrol

  4. Size and surface chemistry of nanoparticles lead to a variant behavior in the unfolding dynamics of human carbonic anhydrase.

    PubMed

    Nasir, Irem; Lundqvist, Martin; Cabaleiro-Lago, Celia

    2015-11-07

    The adsorption induced conformational changes of human carbonic anhydrase I (HCAi) and pseudo wild type human carbonic anhydrase II truncated at the 17th residue at the N-terminus (trHCAii) were studied in presence of nanoparticles of different sizes and polarities. Isothermal titration calorimetry (ITC) studies showed that the binding to apolar surfaces is affected by the nanoparticle size in combination with the inherent protein stability. 8-Anilino-1-naphthalenesulfonic acid (ANS) fluorescence revealed that HCAs adsorb to both hydrophilic and hydrophobic surfaces, however the dynamics of the unfolding at the nanoparticle surfaces drastically vary with the polarity. The size of the nanoparticles has opposite effects depending on the polarity of the nanoparticle surface. The apolar nanoparticles induce seconds timescale structural rearrangements whereas polar nanoparticles induce hours timescale structural rearrangements on the same charged HCA variant. Here, a simple model is proposed where the difference in the timescales of adsorption is correlated with the energy barriers for initial docking and structural rearrangements which are firmly regulated by the surface polarity. Near-UV circular dichorism (CD) further supports that both protein variants undergo structural rearrangements at the nanoparticle surfaces regardless of being "hard" or "soft". However, the conformational changes induced by the apolar surfaces differ for each HCA isoform and diverge from the previously reported effect of silica nanoparticles.

  5. Allelopathic effects of toxic haptophyte Prymnesium parvum lead to release of dissolved organic carbon and increase in bacterial biomass.

    PubMed

    Uronen, Pauliina; Kuuppo, Pirjo; Legrand, Catherine; Tamminen, Timo

    2007-07-01

    The haptophyte Prymnesium parvum has lytic properties, and it affects coexisting phytoplankton species through allelopathy. We studied the effect of P. parvum allelochemicals on the lysis of the nontoxic and nonaxenic cryptomonad Rhodomonas salina and the consequent release of dissolved organic carbon (DOC). Changes in production, cell density, and biomass of associated bacteria were measured over 12 h. Six different combinations of P. parvum and R. salina cultures, their cell- and bacteria-free filtrates, and growth media as controls were used in the experiments. When P. parvum and R. salina cells were mixed, a significant increase in DOC concentration was measured within 30 min. Bacterial biomass increased significantly during the next 6 to 12 h when R. salina was mixed either with the P. parvum culture or the cell-free P. parvum filtrates (allelochemicals only). In contrast, bacterial biomass did not change in the treatments without the allelopathic action (without R. salina cells). Blooms of P. parvum alter the functioning of the planktonic food web by increasing carbon transfer through the microbial loop. In addition, P. parvum may indirectly benefit from the release of DOC as a result of its ability to ingest bacteria, by which it can acquire nutrients during limiting conditions.

  6. Effect of Phosphate Inhibitors on the Formation of Lead Phosphate/Carbonate Nanorods, Microrods and Dendritic Structures

    EPA Science Inventory

    There are several factors which influence the corrosion rate of lead, which in turn morphs into different crystal shapes and sizes. Some of the important factors are: alkalinity, pH, calcium, orthophosphate and silica. Low to moderate alkalinity decreases corrosion rates, while ...

  7. Effect of Phosphate Inhibitors on the Formation of Lead Phosphate/Carbonate Nanorods, Microrods and Dendritic Structures

    EPA Science Inventory

    There are several factors which influence the corrosion rate of lead, which in turn morphs into different crystal shapes and sizes. Some of the important factors are: alkalinity, pH, calcium, orthophosphate and silica. Low to moderate alkalinity decreases corrosion rates, while ...

  8. Understanding the function and performance of carbon-enhanced lead-acid batteries : milestone report for the DOE Energy Storage Systems program (FY11 Quarter 2: January through March 2011).

    SciTech Connect

    Shane, R.; Enos, David George; Hund, Thomas D.

    2011-05-01

    This report describes the status of research being performed under CRADA No. SC10/01771.00 (Lead/Carbon Functionality in VRLA Batteries) between Sandia National Laboratories and East Penn Manufacturing, conducted for the U.S. Department of Energy's Energy Storage Systems Program. The Quarter 2 Milestone was completed on time. The milestone entails an ex situ analysis of the four carbons that have been added to the negative active material of valve-regulated lead-acid (VRLA) batteries for the purposes of this study. The four carbons selected for this study were a graphitic carbon, a carbon black, an activated carbon, and acetylene black. The morphology, crystallinity, and impurity contents of each of the four carbons were analyzed; results were consistent with previous data. Cycling on a subset of the received East Penn cells containing different carbons (and a control) has been initiated. Carbon has been explored as an addition to lead-acid battery electrodes in a number of ways. Perhaps the most notable to date has been the hybrid 'Ultrabattery' developed by CSIRO where an asymmetric carbon-based electrochemical capacitor is combined with a lead-acid battery into a single cell, dramatically improving high-rate partial-state-of-charge (HRPSoC) operation. As illustrated below, the 'Ultrabattery' is a hybrid device constructed using a traditional lead-acid battery positive plate (i.e., PbO{sub 2}) and a negative electrode consisting of a carbon electrode in parallel with a lead-acid negative plate. This device exhibits a dramatically improved cycle life over traditional VRLA batteries, as well as increased charge power and charge acceptance. The 'Ultrabattery' has been produced successfully by both The Furukawa Battery Co. and East Penn Manufacturing. An example illustrating the dramatic improvement in cycle life of the Ultrabattery over a conventional VRLA battery is shown.

  9. Trace level voltammetric determination of lead and cadmium in sediment pore water by a bismuth-oxychloride particle-multiwalled carbon nanotube composite modified glassy carbon electrode.

    PubMed

    Cerovac, Sandra; Guzsvány, Valéria; Kónya, Zoltán; Ashrafi, Amir M; Švancara, Ivan; Rončević, Srđan; Kukovecz, Ákos; Dalmacija, Božo; Vytřas, Karel

    2015-03-01

    Two multiwalled carbon nanotubes-based composites modified with bismuth and bismuth-oxychloride particles were synthesized and attached to the glassy carbon electrode substrate. The resultant configurations, Bi/MWCNT-GCE and BiOCl/MWNT-GCE, were then characterized with respect to their physicochemical properties and electroanalytical performance in combination with square-wave anodic stripping voltammetry (SWASV). Further, some key experimental conditions and instrumental parameters were optimized; namely: the supporting electrolyte composition, accumulation potential and time, together with the parameters of the SWV-ramp. The respective method with both electrode configurations has then been examined for the trace level determination of Pb(2+) and Cd(2+) ions and the results compared to those obtained with classical bismuth-film modified GCE. The different intensities of analytical signals obtained at the three electrodes for Pb(2+) and Cd(2+) vs. the saturated calomel reference electrode had indicated that the nature of the modifiers and the choice of the supporting electrolyte influenced significantly the corresponding stripping signals. The most promising procedure involved the BiOCl/MWCNT-GCE and the acetate buffer (pH 4.0) offering limits of determination of 4.0 μg L(-1) Cd(2+) and 1.9 μg L(-1) Pb(2+) when accumulating for 120 s at a potential of -1.20 V vs. ref. The BiOCl/MWCNT electrode was tested for the determination of target ions in the pore water of a selected sediment sample and the results agreed well with those obtained by graphite furnace atomic absorption spectrometry.

  10. Size and surface chemistry of nanoparticles lead to a variant behavior in the unfolding dynamics of human carbonic anhydrase

    NASA Astrophysics Data System (ADS)

    Nasir, Irem; Lundqvist, Martin; Cabaleiro-Lago, Celia

    2015-10-01

    The adsorption induced conformational changes of human carbonic anhydrase I (HCAi) and pseudo wild type human carbonic anhydrase II truncated at the 17th residue at the N-terminus (trHCAii) were studied in presence of nanoparticles of different sizes and polarities. Isothermal titration calorimetry (ITC) studies showed that the binding to apolar surfaces is affected by the nanoparticle size in combination with the inherent protein stability. 8-Anilino-1-naphthalenesulfonic acid (ANS) fluorescence revealed that HCAs adsorb to both hydrophilic and hydrophobic surfaces, however the dynamics of the unfolding at the nanoparticle surfaces drastically vary with the polarity. The size of the nanoparticles has opposite effects depending on the polarity of the nanoparticle surface. The apolar nanoparticles induce seconds timescale structural rearrangements whereas polar nanoparticles induce hours timescale structural rearrangements on the same charged HCA variant. Here, a simple model is proposed where the difference in the timescales of adsorption is correlated with the energy barriers for initial docking and structural rearrangements which are firmly regulated by the surface polarity. Near-UV circular dichorism (CD) further supports that both protein variants undergo structural rearrangements at the nanoparticle surfaces regardless of being ``hard'' or ``soft''. However, the conformational changes induced by the apolar surfaces differ for each HCA isoform and diverge from the previously reported effect of silica nanoparticles.The adsorption induced conformational changes of human carbonic anhydrase I (HCAi) and pseudo wild type human carbonic anhydrase II truncated at the 17th residue at the N-terminus (trHCAii) were studied in presence of nanoparticles of different sizes and polarities. Isothermal titration calorimetry (ITC) studies showed that the binding to apolar surfaces is affected by the nanoparticle size in combination with the inherent protein stability. 8-Anilino

  11. Using Carbon, Oxygen, Strontium, and Lead Isotopes in Modern Human Teeth for Forensic Investigations: A Critical Overview Based on Data from Bulgaria.

    PubMed

    Kamenov, George D; Curtis, Jason H

    2017-02-23

    Isotopic data obtained from human remains can provide information about an individual's origin, migration, and diet. We evaluate the usefulness of carbon, oxygen, strontium, and lead isotopes for forensic investigations by comparing data from Bulgarian teeth with data from other regions. Geo-referencing based on oxygen or strontium isotopes can be misleading due to overlap with other countries in Europe and other continents. Carbon and lead isotopes, in combination with oxygen and strontium isotopes, provide the most useful information for identification of local vs foreigner status. In particular, high-precision Pb isotopes show a distinct "Bulgarian" range; however, it is possible that individuals from other countries in Eastern Europe and/or central to western Asia could have overlapping isotopic values. Additional high-precision multi-isotope data from modern humans from different regions in the world are required to transition from speculative to more quantitative estimation of a geographical place of origin for unidentified human remains. © 2017 American Academy of Forensic Sciences.

  12. Differential pulse anodic stripping voltammetric determination of lead(II) with a 1,4-bis(prop-2'-enyloxy)-9,10-anthraquinone modified carbon paste electrode.

    PubMed

    Mousavi, M F; Rahmani, A; Golabi, S M; Shamsipur, M; Sharghi, H

    2001-08-30

    A sensitive and selective method for the determination of lead(II) with a 1,4-bis(prop-2'-enyloxy)-9,10-anthraquinone (AQ) modified carbon paste electrode has been developed. The method is based on non-electrolytic preconcentration via complex formation with modifier, followed by an accumulation period with a negative potential (-1.5 V), and then by a proper anodic stripping. The analytical performance was evaluated with respect to the quantity of modifier in the paste, concentration of electrolyte solution, preconcentration time, lead(II) concentration, and other variables. A linear calibration graph was obtained in the concentration range 2.00x10(-9)-1.06x10(-5) M Pb(II) (n=21, r=0.9999) with 30 s preconcentration time. The detection limit was found to be 1x10(-9) M. For eight preconcentration/determination cycles, the differential pulse voltammetric response was reproduced with 5.0 and 3.7% relative standard deviations at 2.00x10(-8) and 2.00x10(-6) M Pb(II), respectively. Rapid and convenient renewal of electrode surface allows the use of a single modified electrode surface in multiple analytical determinations over several weeks. Many coexisting metal ions had little or no effect on the determination of lead(II). The developed method was applied to lead determination in waste waters.

  13. Multiwalled carbon nanotubes as a sorbent material for the solid phase extraction of lead from urine and subsequent determination by electrothermal atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Peña Crecente, Rosa M.; Lovera, Carlha Gutiérrez; García, Julia Barciela; Méndez, Jennifer Álvarez; Martín, Sagrario García; Latorre, Carlos Herrero

    2014-11-01

    The determination of lead in urine is a way of monitoring the chemical exposure to this metal. In the present paper, a new method for the Pb determination by electrothermal atomic absorption spectrometry (ETAAS) in urine at low levels has been developed. Lead was separated from the undesirable urine matrix by means of a solid phase extraction (SPE) procedure. Oxidized multiwalled carbon nanotubes have been used as a sorbent material. Lead from urine was retained at pH 4.0 and was quantitatively eluted using a 0.7 M nitric acid solution and was subsequently measured by ETAAS. The effects of parameters that influence the adsorption-elution process (such as pH, eluent volume and concentration, sampling and elution flow rates) and the atomic spectrometry conditions have been studied by means of different factorial design strategies. Under the optimized conditions, the detection and quantification limits obtained were 0.08 and 0.26 μg Pb L- 1, respectively. The results demonstrate the absence of a urine matrix effect and this is the consequence of the SPE process carried out. Therefore, the developed method is useful for the analysis of Pb at low levels in real samples without the influence of other urine components. The proposed method was applied to the determination of lead in urine samples of unexposed healthy people and satisfactory results were obtained (in the range 3.64-22.9 μg Pb L- 1).

  14. Spectroscopic Studies of Doping and Charge Transfer in Single Walled Carbon Nanotubes and Lead Sulfide Quantum Dots

    NASA Astrophysics Data System (ADS)

    Haugen, Neale O.

    The use of single wall carbon nanotubes (SW-CNTs) in solar photovoltaic (PV) devices is a relatively new, but quickly growing field. SW-CNTs have found application as transparent front contacts, and high work function back contacts in thin film solar PV. For the utility of SW-CNTs to be fully realized, however, controllable and stable doping as well as long term protection from doping must be achieved. Spectroscopic techniques facilitate detailed investigations of the intrinsic and variable properties of semiconductor materials without the issues of contact deposition and the possibility of sample contamination. Detailed spectroscopic analysis of the doping induced changes in the optical properties of SW-CNTs has revealed normally hidden excited state transitions in large diameter single walled carbon nanotubes for the first time. Spectroscopic monitoring of the degree of doping in SW-CNTs made possible studies of the dopant complex desorption and readsorption energies and kinetics. The long term protection from doping of SW-CNTs exposed to ambient laboratory conditions was achieved as a result of the more detailed understanding of the doping processes and mechanisms yielded by these spectroscopic studies. The application of SW-CNTs to other roles in solar PV devices was another goal of this research. Efficient collection of photogenerated charge carriers in semiconductor quantum dot (QD) based solar photovoltaic devices has been limited primarily by the poor transport properties and high density of recombination sites in the QD films. Coupling semiconductor QDs to nanomaterials with better transport properties is one potential solution to the poor transport within the QD films. This portion of the work investigated the possibility of charge transfer occurring in nano-heterostructures (NHSs) of PbS QDs and SW-CNTs produced through spontaneous self-assembly in solution. Electronic coupling in the form of charge transfer from the QDs to the SW-CNTs is unambiguously

  15. Decreased glycolate oxidase activity leads to altered carbon allocation and leaf senescence after a transfer from high CO2 to ambient air in Arabidopsis thaliana.

    PubMed

    Dellero, Younès; Jossier, Mathieu; Glab, Nathalie; Oury, Céline; Tcherkez, Guillaume; Hodges, Michael

    2016-05-01

    Metabolic and physiological analyses of Arabidopsis thaliana glycolate oxidase (GOX) mutant leaves were performed to understand the development of the photorespiratory phenotype after transfer from high CO2 to air. We show that two Arabidopsis genes, GOX1 and GOX2, share a redundant photorespiratory role. Air-grown single gox1 and gox2 mutants grew normally and no significant differences in leaf metabolic levels and photosynthetic activities were found when compared with wild-type plants. To study the impact of a highly reduced GOX activity on plant metabolism, both GOX1 and GOX2 expression was knocked-down using an artificial miRNA strategy. Air-grown amiRgox1/2 plants with a residual 5% GOX activity exhibited a severe growth phenotype. When high-CO2-grown adult plants were transferred to air, the photosynthetic activity of amiRgox1/2 was rapidly reduced to 50% of control levels, and a high non-photochemical chlorophyll fluorescence quenching was maintained. (13)C-labeling revealed that daily assimilated carbon accumulated in glycolate, leading to reduced carbon allocation to sugars, organic acids, and amino acids. Such changes were not always mirrored in leaf total metabolite levels, since many soluble amino acids increased after transfer, while total soluble protein, RuBisCO (ribulose-1,5-bisphosphate carboxylase/oxygenase), and chlorophyll amounts decreased in amiRgox1/2 plants. The senescence marker, SAG12, was induced only in amiRgox1/2 rosettes after transfer to air. The expression of maize photorespiratory GOX in amiRgox1/2 abolished all observed phenotypes. The results indicate that the inhibition of the photorespiratory cycle negatively impacts photosynthesis, alters carbon allocation, and leads to early senescence in old rosette leaves. © The Author 2016. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  16. Graphene-carbon paste electrode for cadmium and lead ion monitoring in a flow-based system.

    PubMed

    Wonsawat, Wanida; Chuanuwatanakul, Suchada; Dungchai, Wijitar; Punrat, Eakkasit; Motomizu, Shoji; Chailapakul, Orawon

    2012-10-15

    An environment friendly electrode for determining Cd(2+) and Pb(2+) levels in an automated flow system was successfully developed. Cyclic voltammetry and square wave anodic stripping voltammetry (SWASV) coupled with sequential injection analysis (SIA) were employed to study the electrochemical behavior of the electrode. The in situ bismuth-modified graphene-carbon paste electrode (Bi-GCPE) exhibited excellent electrooxidation of Cd(2+) and Pb(2+) in the automated flow system with a significantly higher peak current for both metal ions compared with the unmodified CPE. The limits of detection from this method were 0.07 and 0.04 μg L(-1) for Cd(2+) and Pb(2+), respectively, with a linear oxidation peak current response for Cd(2+) and Pb(2+) in the range of 0.10-50.0 μg L(-1) under optimum conditions. The Bi-GCPE was also applied for the determination of Cd(2+) and Pb(2+) in low- (tap water) and high- (sea bass fish and undulated surf clam tissues) matrix complexity samples by automated flow system. The recoveries were acceptable and ranged from 70.4% to 120% for Cd(2+) and 65.8% to 113.5% for Pb(2+).

  17. Morphology-dependent NiO modified glassy carbon electrode surface for lead(II) and cadmium(II) detection

    NASA Astrophysics Data System (ADS)

    Li, Xuewu; Wen, Hao; Fu, Qiang; Peng, Dai; Yu, Jingui; Zhang, Qiaoxin; Huang, Xingjiu

    2016-02-01

    Glassy carbon electrode (GCE) surfaces have been modified with different NiO morphologies consisting of rods NiO, flakes NiO and balls NiO prepared via the hydrothermal synthesis method for Pb(II) and Cd(II) detection by using the square wave anodic stripping voltammetry (SWASV). Meanwhile, the typical cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), BET surface area and adsorption property of the modified electrode surfaces have been investigated to evaluate their electrochemical detection effect. Results show that balls NiO modified GCE can get the optimal detection ability for its highest detection sensitivity to Pb(II) (13.46 A M-1) and Cd(II) (5.10 A M-1), the lowest detection limit (DL) to Pb(II) (0.08 μM) and Cd(II) (0.07 μM) as well as the superior linear relativity. In addition, an enhanced current at redox peaks, lower electron transfer resistance, larger BET surface area and stronger adsorption capacity have been confirmed for the balls NiO modified GCE surface. Finally, excellent stability and reproducibility of balls NiO modified electrodes for Pb(II) and Cd(II) detection have also been proved via the SWASV responses.

  18. Environmental forcing does not lead to diel or synoptic variability in carbon isotope content of forest soil respiration

    NASA Astrophysics Data System (ADS)

    Bowling, D. R.; Egan, J. E.; Hall, S. J.; Risk, D. A.

    2014-12-01

    Recent studies have highlighted fluctuations in the carbon isotope content (d13C) of CO2 produced by soil respiration. These fluctuations have been correlated with diel cycles of environmental forcing (e.g., soil temperature), or with synoptic weather events (e.g., rain events and pressure-induced ventilation). We used an extensive suite of observations to examine these phenomena over two months in a subalpine forest in Colorado, USA (the Niwot Ridge AmeriFlux site). Measurements included automated soil respiration chambers and automated measurements of the soil gas profile. We found 1) no diel change in the d13C of the soil surface flux or the CO2 produced in the soil (despite strong diel change in surface flux rate), 2) no change in d13C following wetting (despite a significant increase in soil flux rate), and 3) no evidence of pressure-induced ventilation of the soil. Measurements of the d13C of surface CO2 flux agreed closely with the isotopic composition of soil CO2 production calculated using soil profile measurements. Temporal variation in the d13C of surface flux was relatively minor and unrelated to measured environmental variables. Deep in the soil profile, results conform to established theory regarding diffusive soil gas transport and isotopic fractionation, and suggest that sampling soil gas at a depth of several tens of centimeters is a simple and effective way to assess the mean d13C of the surface flux.

  19. Hydration Leads to Efficient Reactions of the Carbonate Radical Anion with Hydrogen Chloride in the Gas Phase.

    PubMed

    Tang, Wai Kit; van der Linde, Christian; Siu, Chi-Kit; Beyer, Martin K

    2017-01-12

    The carbonate radical anion CO3(•-) is a key intermediate in tropospheric anion chemistry. Despite its radical character, only a small number of reactions have been reported in the literature. Here we investigate the gas-phase reactions of CO3(•-) and CO3(•-)(H2O) with HCl under ultrahigh vacuum conditions. Bare CO3(•-) forms OHCl(•-) with a rate constant of 4.2 × 10(-12) cm(3) s(-1), which corresponds to an efficiency of only 0.4%. Hydration accelerates the reaction, and ligand exchange of H2O against HCl proceeds with a rate of 2.7 × 10(-10) cm(3) s(-1). Quantum chemical calculations reveal that OHCl(•-) is best described as an OH(•) hydrogen bonded to Cl(-), while the ligand exchange product is Cl(-)(HCO3(•)). Under tropospheric conditions, where CO3(•-)(H2O) is the dominant species, Cl(-)(HCO3(•)) is efficiently formed. These reactions must be included in models of tropospheric anion chemistry.

  20. Removal of chromium and lead by a sulfate-reducing consortium using peat moss as carbon source.

    PubMed

    Márquez-Reyes, Julia Mariana; López-Chuken, Ulrico Javier; Valdez-González, Arcadio; Luna-Olvera, Hugo Alberto

    2013-09-01

    The effect of pre-treated peat moss on the ability of a sulfate-reducing microbial consortium to remove chromium and lead in solution was evaluated. The most active bacterial community (235.7 mmol H2S/g VSS) was selected from among eight consortia. The peat moss was pre-treated with different HCl concentrations and contact times. The best combination of treatments was 20% HCl for 10 min. The constant substrate affinity Ks was 740 mg COD/L and the ratio COD/SO4(2-) was 0.71. At pH 5, higher production of biogenic sulfide was observed. The up-flowpacked bed bioreactor operated at a flow of 8.3 mL/min for 180 h to obtain removal efficiency (by sulfate-reducing activity) of 90% lead and 65% chromium. It is important to consider that peat moss is a natural adsorbent that further influences the removal efficiency of metal ions.

  1. Comparison of biomass and lipid production under ambient carbon dioxide vigorous aeration and 3% carbon dioxide condition among the lead candidate Chlorella strains screened by various photobioreactor scales.

    PubMed

    Kobayashi, Naoko; Barnes, Austin; Jensen, Travis; Noel, Eric; Andlay, Gunjan; Rosenberg, Julian N; Betenbaugh, Michael J; Guarnieri, Michael T; Oyler, George A

    2015-12-01

    Chlorella species from the UTEX collection, classified by rDNA-based phylogenetic analysis, were screened based on biomass and lipid production in different scales and modes of culture. The lead candidate strains of C. sorokiniana UTEX 1230 and C. vulgaris UTEX 395 and 259 were compared between conditions of vigorous aeration with filtered atmospheric air and 3% CO2 shake-flask cultivation. The biomass of UTEX 1230 produced 2 times higher at 652 mg L(-1) dry weight under both ambient CO2 vigorous aeration and 3% CO2 conditions, while UTEX 395 and 259 under 3% CO2 increased to 3 times higher at 863 mg L(-1) dry weight than ambient CO2 vigorous aeration. The triacylglycerol contents of UTEX 395 and 259 increased more than 30 times to 30% dry weight with 3% CO2, indicating that additional CO2 is essential for both biomass and lipid accumulation in UTEX 395 and 259.

  2. Understanding the function and performance of carbon-enhanced lead-acid batteries : milestone report for the DOE Energy Storage Systems program (FY11 Quarter 1: October through December 2010).

    SciTech Connect

    Shane, R.; Enos, David George; Hund, Thomas D.

    2011-05-01

    This report describes the status of research being performed under CRADA No. SC10/01771.00 (Lead/Carbon Functionality in VRLA Batteries) between Sandia National Laboratories and East Penn Manufacturing, conducted for the U.S. Department of Energy's Energy Storage Systems Program. The Quarter 1 Milestone was completed on time. The milestone entails conducting a thorough literature review to establish the current level of understanding of the mechanisms through which carbon additions to the negative active material improve valve-regulated lead-acid (VRLA) batteries. Most studies have entailed phenomenological research observing that the carbon additions prevent/reduce sulfation of the negative electrode; however, no understanding is available to provide insight into why certain carbons are successful while others are not. Impurities were implicated in one recent review of the electrochemical behavior of carbon additions. Four carbon samples have been received from East Penn Manufacturing and impurity contents have been analyzed. Carbon has been explored as an addition to lead-acid battery electrodes in a number of ways. Perhaps the most notable to date has been the hybrid 'Ultrabattery' developed by CSIRO where an asymmetric carbon-based electrochemical capacitor is combined with a lead-acid battery into a single cell, dramatically improving high-rate partial-state-of-charge (HRPSoC) operation. As illustrated below, the 'Ultrabattery' is a hybrid device constructed using a traditional lead-acid battery positive plate (i.e., PbO{sub 2}) and a negative electrode consisting of a carbon electrode in parallel with a lead-acid negative plate. This device exhibits a dramatically improved cycle life over traditional VRLA batteries, as well as increased charge power and charge acceptance. The 'Ultrabattery' has been produced successfully by both The Furukawa Battery Co. and East Penn Manufacturing. An example illustrating the dramatic improvement in cycle life of the

  3. Comparison of Biomass and Lipid Production under Ambient Carbon Dioxide Vigorous Aeration and 3% Carbon Dioxide Condition Among the Lead Candidate Chlorella Strains Screened by Various Photobioreactor Scales

    SciTech Connect

    Kobayashi, Naoko; Barnes, Austin; Jensen, Travis; Noel, Eric; Andlay, Gunjan; Rosenberg, Julian N.; Betenbaugh, Michael J.; Guarnieri, Michael T.; Oyler, George A.

    2015-09-01

    Chlorella species from the UTEX collection, classified by rDNA-based phylogenetic analysis, were screened based on biomass and lipid production in different scales and modes of culture. Lead candidate strains of C. sorokiniana UTEX 1230 and C. vulgaris UTEX 395 and 259 were compared between conditions of vigorous aeration with filtered atmospheric air and 3% CO2 shake-flask cultivation. We found that the biomass of UTEX 1230 produced 2 times higher at 652 mg L-1 dry weight under both ambient CO2 vigorous aeration and 3% CO2 conditions, while UTEX 395 and 259 under 3% CO2 increased to 3 times higher at 863 mg L-1 dry weight than ambient CO2 vigorous aeration. The triacylglycerol contents of UTEX 395 and 259 increased more than 30 times to 30% dry weight with 3% CO2, indicating that additional CO2 is essential for both biomass and lipid accumulation in UTEX 395 and 259.

  4. Conversion from forests to pastures in the Colombian Amazon leads to contrasting soil carbon dynamics depending on land management practices.

    PubMed

    Navarrete, Diego; Sitch, Stephen; Aragão, Luiz E O C; Pedroni, Lucio

    2016-10-01

    Strategies to mitigate climate change by reducing deforestation and forest degradation (e.g. REDD+) require country- or region-specific information on temporal changes in forest carbon (C) pools to develop accurate emission factors. The soil C pool is one of the most important C reservoirs, but is rarely included in national forest reference emission levels due to a lack of data. Here, we present the soil organic C (SOC) dynamics along 20 years of forest-to-pasture conversion in two subregions with different management practices during pasture establishment in the Colombian Amazon: high-grazing intensity (HG) and low-grazing intensity (LG) subregions. We determined the pattern of SOC change resulting from the conversion from forest (C3 plants) to pasture (C4 plants) by analysing total SOC stocks and the natural abundance of the stable isotopes (13) C along two 20-year chronosequences identified in each subregion. We also analysed soil N stocks and the natural abundance of (15) N during pasture establishment. In general, total SOC stocks at 30 cm depth in the forest were similar for both subregions, with an average of 47.1 ± 1.8 Mg C ha(-1) in HG and 48.7 ± 3.1 Mg C ha(-1) in LG. However, 20 years after forest-to-pasture conversion SOC in HG decreased by 20%, whereas in LG SOC increased by 41%. This net SOC decrease in HG was due to a larger reduction in C3-derived input and to a comparatively smaller increase in C4-derived C input. In LG both C3- and C4-derived C input increased along the chronosequence. N stocks were generally similar in both subregions and soil N stock changes during pasture establishment were correlated with SOC changes. These results emphasize the importance of management practices involving low-grazing intensity in cattle activities to preserve SOC stocks and to reduce C emissions after land-cover change from forest to pasture in the Colombian Amazon.

  5. The voltammetric behaviour of lead at a microband screen-printed carbon electrode and its determination in acetate leachates from glazed ceramic plates.

    PubMed

    Honeychurch, Kevin C; Al-Berezanchi, Saman; Hart, John P

    2011-05-15

    Microband screen-printed carbon electrodes (μBSPCEs) without further modification have been investigated as disposable sensors for the measurement of lead in acetate leachates from ceramic glazed plates. Cyclic voltammetry was employed to elucidate the electrochemical behaviour of Pb(2+) at these electrodes in a variety of supporting electrolytes. The anodic peaks obtained on the reverse scans, showed that Pb had been deposited as a thin layer on the surface of the μBSPCE. The anodic peak of greatest magnitude was obtained in 0.1M pH 4.1 acetate buffer containing 13 mM Cl(-). The effect of chromium, copper, phosphate, sulphate and tin was examined and under the conditions employed, no significant change in current was found. The μBSPCEs were evaluated by carrying out lead determinations for acetate leachates from glazed ceramic plates. A highly decorated ornamental plate was found to leach 400 μg Pb(2+) (%CV=1.91%). A second plate, designed for dinnerware was found not to leach any detectable levels of Pb(2+). However, once fortified with 2.10 μg of Pb (equivalent to 100 ng/ml in the leachate), a mean recovery of 82.08% (%CV=4.07%) was obtained. The performance characteristics indicate that reliable data has been obtained for this application which could identify potentially toxic sources of lead. Copyright © 2011 Elsevier B.V. All rights reserved.

  6. Scale-up of Novel Low-Cost Carbon Fibers Leading to High-Volume Commercial Launch

    SciTech Connect

    Spalding, Mark A

    2014-08-27

    The project started in September, 2012 with the goal of scaling up from the existing laboratory scale process for producing carbon fiber (CF) from polyolefin (PO) based precursor fiber using a Dow proprietary sulfonation-desulfonation stabilization process. The award was used to develop a process that was capable of producing market development quantities of CF from PO precursor fiber at a rate of 4 kg/h of CF. The CF would target properties that met or exceeded the Department of Energy (DOE) Vehicles Technology [1] standard; i.e., 172 GPa modulus and 1.72 GPa strength at greater than or equal to 1% strain. The Dow proprietary process was capable of meeting and exceeding these targets properties. Project DE-EE0005760 resulted from a Collaborative Research and Development Agreement (CRADA) between Dow and Oak Ridge National Laboratory (ORNL) with support from the Michigan Economic Development Corporation (MEDC) and DOE. In the first budget period, the main goal was to design a sulfonation-desulfonation market development plant capable of stabilizing PO precursor fiber at a rate of 5 kg/h using a sulfonation solution. The detailed design, location, and cost estimate were determined as scheduled in the Project Management Plan (PMP). In parallel with this DOE award project was a fundamentals and economic evaluation funded by The Dow Chemical Company (Dow). The goal of the Dow sponsored project was to finalize the mass balances, energy balances, and levelized cost to produce CF using the Dow process. A Go-No-Go decision was scheduled in June, 2013 based on the findings of the DOE sponsored scale up project and the Dow sponsored project. In June, 2013, Dow made the No-Go decision to halt and abandon the Dow proprietary sulfonation-desulfonation process for stabilizing PO precursor fibers for the manufacturing of CF. This No-Go decision was identified in the original proposal and at the start of this project, and the decision was made as scheduled. The decision was based

  7. Simultaneous Detection of Cadmium, Copper, and Lead using A Carbon Paste Electrode Modified with Carbamoylphosphonic Acid Self-Assembled Monolayer on Mesoporous Silica (SAMMS)

    SciTech Connect

    Yantasee, Wassana ); Lin, Yuehe ); Fryxell, Glen E. ); Busche, Brad J. )

    2004-01-30

    A new sensor was developed for simultaneous detection of cadmium (Cd2+), copper (Cu2+), and lead (Pb2+), based on the voltammetric response at a carbon paste electrode modified with carbamoylphosphonic acid (acetamide phosphonic acid) self-assembled monolayer on mesoporous silica (Ac-Phos SAMMS). The adsorptive stripping voltammetry technique involves preconcentration of the metal ions onto Ac-Phos SAMMS under an open circuit, then electrolysis of the preconcentrated species, followed by a square wave potential sweep towards positive values. Factors affecting the preconcentration process were investigated. The voltammetric responses increased linearly with the preconcentration time from 1 to 30 minutes or with metal ion concentrations ranging from 10 to 200 ppb. The responses also evolved in the same fashion as adsorption isotherm in the pH range of 2-6. The metal detection limits were 10 ppb after 2 minutes preconcentration and improved to 0.5 ppb after 20 minutes preconcentration.

  8. Attachment of carbohydrates to methoxyaryl moieties leads to highly selective inhibitors of the cancer associated carbonic anhydrase isoforms IX and XII.

    PubMed

    Riafrecha, Leonardo E; Rodríguez, Oscar M; Vullo, Daniela; Supuran, Claudiu T; Colinas, Pedro A

    2014-10-01

    The transmembrane isoforms of carbonic anhydrase (hCA IX and XII) have been shown to be linked to carcinogenesis and their inhibition to arrest primary tumor and metastases growth. In this paper, we present a new class of C-glycosides incorporating the methoxyaryl moiety, that was designed to selectively target and inhibit the extracellular domains of the cancer-relevant CA isozymes. The glycosides have been prepared by aldol reaction of glycosyl ketones with the appropriate aromatic aldehydes. We also present the inhibition profile of our new glycomimetics, against four isozymes of carbonic anhydrase comprising hCAs I and II (cytosolic, ubiquitous isozymes) and hCAs IX and XII (tumor associated isozymes). In this study, per-O-acetylated glycoside 4, 6 and deprotected compounds 7, 9, 10 and 12 were identified as potent and highly selective inhibitors of hCA IX and XII. These results confirm that attaching carbohydrate moieties to CA methoxyaryl pharmacophore improves and enhances its inhibitory activity. These CA inhibitors have developmental potential to selectively target cancer cells, leading to cell death. Copyright © 2014 Elsevier Ltd. All rights reserved.

  9. Voltammetric detection of lead(II) and mercury(II) using a carbon paste electrode modified with thiol self-assembled monolayer on mesoporous silica (SAMMS).

    PubMed

    Yantasee, Wassana; Lin, Yuehe; Zemanian, Thomas S; Fryxell, Glen E

    2003-05-01

    The anodic stripping voltammetry at a carbon paste electrode modified with thiol terminated self-assembled monolayer on mesoporous silica (SH-SAMMS) provides a new sensor for simultaneous detection of lead (Pb2+) and mercury (Hg2+) in aqueous solutions. The overall analysis involved a two-step procedure: an accumulation step at open circuit, followed by medium exchange to a pure electrolyte solution for the stripping analysis. Factors affecting the performance of the SH-SAMMS modified electrodes were investigated, including electrode activation and regeneration, electrode composition, preconcentration time, electrolysis time, and composition of electrolysis and stripping media. The most sensitive and reliable electrode contained 20% SH-SAMMS and 80% carbon paste. The optimal operating conditions were a sequence with a 2 min preconcentration period, then a 60 s electrolysis period of the preconcentrated species in 0.2 M nitric acid, followed by square wave anodic stripping voltammetry from -1.0 V to 0.6 V in 0.2 M nitric acid. The areas of the peak responses were linear with respect to metal ion concentrations in the ranges of 10-1500 ppb Pb2+ and 20-1600 ppb Hg2+. The detection limits for Pb2+ and Hg2+ were 0.5 ppb Pb2+ and 3 ppb Hg2+ after a 20 min preconcentration period.

  10. An ultrasensitive sandwich-type electrochemical immunosensor based on signal amplification strategy of gold nanoparticles functionalized magnetic multi-walled carbon nanotubes loaded with lead ions.

    PubMed

    Li, Faying; Han, Jian; Jiang, Liping; Wang, Yulan; Li, Yueyun; Dong, Yunhui; Wei, Qin

    2015-06-15

    In this study, a novel and ultrasensitive sandwich-type electrochemical immunosensor was prepared for the quantitative detection of alpha fetoprotein (AFP), a well-known hepatocellular carcinoma biomarker. Gold nanoparticles (Au NPs) functionalized magnetic multi-walled carbon nanotubes (MWCNTs-Fe3O4) were prepared and utilized for the adsorption of lead ions (Pb(2+)) and the secondary antibodies (Ab2). The resultant nanocomposites (Pb(2+)@Au@MWCNTs-Fe3O4) were used as the label for signal amplification, showing better electrocatalytic activity towards the reduction of hydrogen peroxide (H2O2) than MWCNTs, MWCNTs-Fe3O4 or Au@MWCNTs-Fe3O4 due to the synergetic effect presented in Pb(2+)@Au@MWCNTs-Fe3O4. Moreover, Au NPs were electrodeposited on the surface of glassy carbon electrode (GCE) for the effective immobilization of primary antibodies (Ab1). Under the optimal conditions, a linear range from 10 fg/mL to 100 ng/mL and a detection limit of 3.33 fg/mL were obtained. The proposed electrochemical sandwich-type immunosensor shows high sensitivity, good selectivity and stability for the quantitative detection of AFP, holding a great potential in clinical and diagnostic applications.

  11. Lead recovery and high silica glass powder synthesis from waste CRT funnel glasses through carbon thermal reduction enhanced glass phase separation process.

    PubMed

    Xing, Mingfei; Fu, Zegang; Wang, Yaping; Wang, Jingyu; Zhang, Zhiyuan

    2017-01-15

    In this study, a novel process for the removal of toxic lead from the CRT funnel glass and synchronous preparation of high silica glass powder was developed by a carbon-thermal reduction enhanced glass phase separation process. CRT funnel glass was remelted with B2O3 in reducing atmosphere. In the thermal process, a part of PbO contained in the funnel glass was reduced into metallic Pb and detached from the glass phase. The rest of PbO and other metal oxides (including Na2O, K2O, Al2O3, BaO and CaO) were mainly concentrated in the boric oxide phase. The metallic Pb phase and boric oxide phase were completely leached out by 5mol/L HNO3. The lead removal rate was 99.80% and high silica glass powder (SiO2 purity >95wt%) was obtained by setting the temperature, B2O3 added amount and holding time at 1000°C, 20% and 30mins, respectively. The prepared high silicate glass powders can be used as catalyst carrier, semipermeable membranes, adsorbents or be remelted into high silicate glass as an ideal substitute for quartz glass. Thus this study proposed an eco-friendly and economical process for recycling Pb-rich electronic glass waste.

  12. Magnetic Particle-Based Immunoassay of Phosphorylated p53 Using Protein-Cage Templated Lead Phosphate and Carbon Nanospheres for Signal Amplification

    SciTech Connect

    Chen, Aiqiong; Bao, Yuanwu; Ge, Xiaoxiao; Shin, Yongsoon; Du, Dan; Lin, Yuehe

    2012-11-20

    Phosphorylated p53 at serin 15 (phospho-p53-15) is a potential biomarker of Gamma-radiation exposure. In this paper, we described a new magnetic particles (MPs)-based electrochemical immunoassay of human phospho-p53-15 using carbon nanospheres (CNS) and protein-cage templated lead phosphate nanoparticles for signal amplification. Greatly enhanced sensitivity was achieved by three aspects: 1) The protein-cage nanoparticle (PCN) and p53-15 signal antibody (p53-15 Ab2) are linked to CNS (PCNof each apoferritin; 3) MPs capture a large amount of primary antibodies. Using apoferritin templated metallic phosphate instead of enzyme as label has the advantage of eliminating the addition of mediator or immunoreagents and thus makes the immunoassay system simpler. The subsequent stripping voltammetric analysis of the released lead ions were detected on a disposable screen printed electrode. The response current was proportional to the phospho-p53-15 concentration in the range of 0.02 to 20 ng mL-1 with detection limit of 0.01 ng mL-1. This method shows a good stability, reproducibility and recovery.

  13. Determination of Zinc, Cadmium, Lead, Copper and Silver Using a Carbon Paste Electrode and a Screen Printed Electrode Modified with Chromium(III) Oxide

    PubMed Central

    Koudelkova, Zuzana; Syrovy, Tomas; Ambrozova, Pavlina; Moravec, Zdenek; Kubac, Lubomir; Hynek, David; Adam, Vojtech

    2017-01-01

    In this study, the preparation and electrochemical application of a chromium(III) oxide modified carbon paste electrode (Cr-CPE) and a screen printed electrode (SPE), made from the same material and optimized for the simple, cheap and sensitive simultaneous determination of zinc, cadmium, lead, copper and the detection of silver ions, is described. The limits of detection and quantification were 25 and 80 µg·L−1 for Zn(II), 3 and 10 µg·L−1 for Cd(II), 3 and 10 µg·L−1 for Pb(II), 3 and 10 µg·L−1 for Cu(II), and 3 and 10 µg·L−1 for Ag(I), respectively. Furthermore, this promising modification was transferred to the screen-printed electrode. The limits of detection for the simultaneous determination of zinc, cadmium, copper and lead on the screen printed electrodes were found to be 350 µg·L−1 for Zn(II), 25 µg·L−1 for Cd(II), 3 µg·L−1 for Pb(II) and 3 µg·L−1 for Cu(II). Practical usability for the simultaneous detection of these heavy metal ions by the Cr-CPE was also demonstrated in the analyses of wastewaters. PMID:28792450

  14. Selective dispersive micro solid-phase extraction using oxidized multiwalled carbon nanotubes modified with 1,10-phenanthroline for preconcentration of lead ions.

    PubMed

    Feist, Barbara

    2016-10-15

    A dispersive micro solid phase extraction (DMSPE) method for the selective preconcentration of trace lead ions on oxidized multiwalled carbon nanotubes (ox-MWCNTs) with complexing reagent 1,10-phenanthroline is presented. Flame and electrothermal atomic absorption spectrometry (F-AAS, ET-AAS) were used for detection. The influence of several parameters such as pH, amount of sorbent and 1,10-phenanthroline, stirring time, concentration and volume of eluent, sample flow rate and sample volume was examined using batch procedures. Moreover, effects of inorganic matrix on recovery of the determined elements were studied. The experiment shows that foreign ions did not influence on recovery of the determined element. The method characterized by high selectivity toward Pb(II) ions. Lead ions can be quantitatively retained at pH 7 from sample volume up to 400mL and then eluent completely with 2mL of 0.5molL(-1)HNO3. The detection limits of Pb was 0.26μgL(-1) for F-AAS and 6.4ngL(-1) for ET-AAS. The recovery of the method for the determined lead was better than 97% with relative standard deviation lower than 3.0%. The preconcentration factor was 200 for F-AAS and 100 for ET-AAS. The maximum adsorption capacity of the adsorbent was found to be about 350mgg(-1). The method was applied for determination of Pb in fish samples with good results. Accuracy of the method was verified using certified reference material DOLT-3 and ERM-BB186.

  15. Windblown Lead Carbonate as the Main Source of Lead in Blood of Children from a Seaside Community: An Example of Local Birds as “Canaries in the Mine”

    PubMed Central

    Gulson, Brian; Korsch, Michael; Matisons, Martin; Douglas, Charles; Gillam, Lindsay; McLaughlin, Virginia

    2009-01-01

    Background In late 2006, the seaside community in Esperance, Western Australia, was alerted to thousands of native bird species dying. The source of the lead was thought to derive from the handling of Pb carbonate concentrate from the Magellan mine through the port of Esperance, begun in July 2005. Concern was expressed for the impact of this process on the community. Objective This study was designed to evaluate the source of Pb in blood of a random sample of the community using Pb isotope ratios. Methods The cohort comprised 49 children (48 < 5 years of age) along with 18 adults (> 20 years of age) with a bias toward higher blood lead (PbB) values to facilitate source identification. Results Mean PbB level of the children was 7.5 μg/dL (range, 1.5–25.7 μg/dL; n = 49; geometric mean, 6.6 μg/dL), with four children whose PbB was > 12 μg/dL. The isotopic data for blood samples lay around two distinct arrays. The blood of all children analyzed for Pb isotopes contained a contribution of Pb from the Magellan mine, which for young children ranged from 27% up to 93% (mean, 64%; median, 71%). Subtraction of the ore component gave a mean background PbB of 2.3 μg/dL. Several children whose PbB was > 9 μg/dL and most of the older subjects have complex sources of Pb. Conclusions The death of the birds acted as a sentinel event; otherwise, the exposure of the community, arising from such a toxic form of Pb, could have been tragic. Isotopic data and mineralogic and particle size analyses indicate that, apart from the recognized pathway of Pb exposure by hand-to-mouth activity in children, the inhalation pathway could have been a significant contributor to PbB for some of the very young children and in some parents. PMID:19165402

  16. Evaluation of the continuous rate of supply lead-210 sediment age model: Two sources of potential bias and implications for carbon burial rates

    NASA Astrophysics Data System (ADS)

    Gonneea, M. E.; Kroeger, K. D.

    2016-12-01

    The past century has been a period of rapid environmental change and ecosystem response to this change is of great interest, particularly in coastal wetlands. Lead-210 is an important sediment chronometer that yields accurate dates over the past century in sediments typically considered too young for carbon-14 dates. Since originally proposed by Appleby and Oldfield in 1978, sediments from a wide range of environments, including salt marshes and mangroves, have been dated with the lead-210 continuous rate of supply (CRS) age model. The power of this model is that it allows ages and accretion rates to be calculated for each interval with measured 210Pb activity, as opposed to a single accretion rate using the constant initial concentration model. There are two sources of potential bias in the model as it is applied to real 210Pb sediment profiles. First, the formulation originally proposed to calculate the mass accretion rate is sensitive to the thickness of sediment sampling intervals, and results in underestimation of mass accretion rates at typical (1 to 2 cm) sampling intervals. Such underestimation is greatest for large intervals and small accretion rates. For example, 1 cm intervals would result in 15% and 2 cm intervals in 22% underestimation for a 1 mm y-1 linear sedimentation rate. Secondly, the continuous rate of supply model requires integration of the total 210Pb profile; failure to measure the entire profile results in calculated ages that are too old and accretion rates that are too low. We propose that 210Pb profiles must be counted to an age of 200 years to avoid this bias within sediments deposited over the past century; profiles integrated to 150 years underestimate accretion rates by 22% at 100 years. It is possible to estimate the sediment concentration of 210Pb at 200 years as a function of 210Pb supply from the atmosphere, sedimentation rate and dry bulk density. Using published core data, we demonstrate that it is particularly important to

  17. Sulphur limitation provokes physiological and leaf proteome changes in oilseed rape that lead to perturbation of sulphur, carbon and oxidative metabolisms

    PubMed Central

    2013-01-01

    Background The decline in industrial emissions of sulphur (S) has led to a sulphate depletion in soil resulting in an alteration of crop performance. In oilseed rape, an S deficiency dramatically reduced the seed yield and/or quality. Paradoxically, little is known about the impact of sulphate limitation on oilseed rape leaf metabolism, despite it being a key determinant of growth. In order to identify the metabolic processes involved in the oilseed rape response to S restriction, an analysis of the young leaf proteome combined with a physiological study was carried out at the vegetative stage. Results S limitation does not significantly reduce the total shoot biomass but inhibits growth and photosynthesis of young leaves. This photosynthesis decline is not due to a decrease in chlorophyll content, which remains similar to Control. The increase in anthocyanins and H2O2 content in young leaves of S-limited plants suggests that S restriction leads to an oxidative stress. Proteomic analysis at 35 d of S limitation also revealed the induction of 12-oxophitodienoate reductase and ACC synthase, respectively involved in jasmonate and ethylene biosynthesis, two phytohormones that could be implicated in oxidative stress. Proteins involved in photosynthesis and carbon metabolism were also modulated by S restriction. In particular, the decrease in plastocyanin and ferredoxin–NADP reductase suggests that H2O2 accumulation is associated with perturbation of the photosynthetic electron transport chain. The accumulation of chloroplastic Cu-Zn SOD reinforces the idea that an oxidative stress probably occurs in the chloroplast. Proteomic results suggest that the maintenance of chlorophyll in S-limited conditions is related to an accumulation of Water Soluble Chlorophyll binding Proteins, involved in the protection of chlorophyll against ROS. The accumulation of the catalytic α–subunit of chloroplastic ATP synthase suggests that energy production is maintained. Conclusion S

  18. LEADING WITH LEADING INDICATORS

    SciTech Connect

    PREVETTE, S.S.

    2005-01-27

    This paper documents Fluor Hanford's use of Leading Indicators, management leadership, and statistical methodology in order to improve safe performance of work. By applying these methods, Fluor Hanford achieved a significant reduction in injury rates in 2003 and 2004, and the improvement continues today. The integration of data, leadership, and teamwork pays off with improved safety performance and credibility with the customer. The use of Statistical Process Control, Pareto Charts, and Systems Thinking and their effect on management decisions and employee involvement are discussed. Included are practical examples of choosing leading indicators. A statistically based color coded dashboard presentation system methodology is provided. These tools, management theories and methods, coupled with involved leadership and employee efforts, directly led to significant improvements in worker safety and health, and environmental protection and restoration at one of the nation's largest nuclear cleanup sites.

  19. Insight into highly efficient co-removal of p-nitrophenol and lead by nitrogen-functionalized magnetic ordered mesoporous carbon: Performance and modelling.

    PubMed

    Zhou, Yaoyu; Liu, Xiaocheng; Tang, Lin; Zhang, Fengfeng; Zeng, Guangming; Peng, Xiangqi; Luo, Lin; Deng, Yaochen; Pang, Ya; Zhang, Jiachao

    2017-03-16

    Highly efficient simultaneous removal of Pb(II) and p-nitrophenol (PNP) contamination from water was accomplished by nitrogen-functionalized magnetic ordered mesoporous carbon (N-Fe/OMC). The mutual effects and inner mechanisms of their adsorption onto N-Fe/OMC were systematically investigated by sole and binary systems, and thermodynamic, sorption isotherm and adsorption kinetics models. The liquid-film diffusion step might be the rate-limiting step for PNP and Pb(II). The fitting of experimental data with Temkin model indicates that the adsorption process of PNP and Pb(II) involve physisorption and chemisorption. There exist site competition and enhancement of PNP and Pb(II) on the sorption to N-Fe/OMC. Moreover, N-Fe/OMC could be regenerated effectively and recycled by using dilute NaOH and acetone. These demonstrated superior properties of N-Fe/OMC indicate that it could be applied to treatment of wastewaters containing both lead and PNP.

  20. Magnetic multi-wall carbon nanotube nanocomposite as an adsorbent for preconcentration and determination of lead (II) and manganese (II) in various matrices.

    PubMed

    Daneshvar Tarigh, Ghazale; Shemirani, Farzaneh

    2013-10-15

    Magnetic multi-wall carbon nanotube (MMWCNT) nanocomposite was synthesized and used as an adsorbent for preconcentration and determination of lead (II) and manganese (II). The properties of MMWCNT were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Energy dispersive X-ray spectrometry (EDS) and fourier transform infrared spectrophotometer (FT-IR). This adsorbent was found to be advantageous over conventional solid phase extraction (SPE) in terms of operational simplicity and low time-consuming. MMWCNT, carrying target metals, was easily separated from the aqueous solutions with the help of an external magnet; so, no filtration or centrifugation was necessary. After extraction and collection of MMWCNT, the adsorbed analytes were eluted and analyzed by flame atomic absorption spectrometry (FAAS). Experiments were carried out to investigate the influence of different sorption/desorption parameters. Under the optimized conditions, detection limits and enhancement factors of the proposed method for Pb and Mn were 1.0 and 0.6 µg L(-1), 390 and 697 respectively. The presented procedure was successfully applied for determination of Pb(II) and Mn (II) contents in lipstick, rice samples and accuracy was evaluated analyzing a certified reference material Seronorm(™) Urine LOT NO2525. Copyright © 2013 Elsevier B.V. All rights reserved.

  1. Carboxylated multi-walled carbon nanotubes aggravated biochemical and subcellular damages in leaves of broad bean (Vicia faba L.) seedlings under combined stress of lead and cadmium.

    PubMed

    Wang, Chengrun; Liu, Haitao; Chen, Jinyun; Tian, Yuan; Shi, Jian; Li, Dongdong; Guo, Chen; Ma, Qingping

    2014-06-15

    Increasing industrialization of multi-walled carbon nanotubes (MWCNTs) would inevitably lead to their release into the environment and combination with heavy metals. However, studies concerning the combined effects of MWCNTs and heavy metals on agricultural crops are limited. Herein, effects and mechanisms of carboxylated MWCNTs (MWCNTs-COOH) (2.5, 5 and 10mg/L) and their combination with 20 μM Pb and 5 μM Cd (shortened as Pb+Cd) on Vicia faba L. seedlings were investigated. The results showed that the MWCNTs-COOH disturbed the imbalance of nutrient elements, and caused oxidative stress and damages in the leaves. Additionally, the combination of MWCNTs-COOH with Pb+Cd resulted in enrichment of Pb and Cd, and deterioration of oxidative damages compared with the treatments of MWCNTs-COOH or Pb+Cd alone in the leaves. As the results, the concentrations of MWCNTs-COOH not only caused oxidative stress, but also exacerbated the biochemical and subcellular damages due to the treatment of Pb+Cd in the leaves. It also suggests that persistent release of MWCNTs-COOH into the environment may cause phytotoxicity and aggravate ecological risks due to combination of heavy metals.

  2. Synthesis and application of novel ion-imprinted polymer coated magnetic multi-walled carbon nanotubes for selective solid phase extraction of lead(II) ions.

    PubMed

    Fayazi, Maryam; Taher, Mohammad Ali; Afzali, Daryoush; Mostafavi, Ali; Ghanei-Motlagh, Masoud

    2016-03-01

    In this study, novel magnetic ion-imprinted polymer (MIIP) nanoparticles were utilized for the sensitive and selective detection of Pb(II) ions by graphite furnace atomic absorption spectrometry (GFAAS). The Pb(II)-imprinted polymer was synthesized by using 4-vinylpyridine (4VP) as the functional monomer, ethylene glycol dimethacrylate (EGDMA) as the cross-linker, 2,3,5,6-tetra(2-pyridyl) pyrazine (TPPZ) as the chelating agent and magnetic multi-walled carbon nanotubes (MMWCNTs) as the carrier. The synthesized MIIP materials were characterized by field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and vibrating sample magnetometer (VSM). Various analytical parameters such as extraction and desorption time, eluent type and concentration, pH and sample volume were systematically examined. The selectivity of MIIP sorbent for Pb(II) ions in the presence of some cations was also evaluated. The limit of detection (LOD, 3S(b)) and the relative standard deviation (RSD, n=8, c=25 ng L(-1)) were found to be 2.4 ng L(-1) and 5.6%, respectively. The maximum sorption capacity of the MIIP for Pb(II) was found to be 48.1 mg g(-1). Finally, the proposed analytical procedure was successfully applied to monitoring lead in human hair and water samples with satisfactory results for the spiked samples. Copyright © 2015 Elsevier B.V. All rights reserved.

  3. Transient accident analysis of a supercritical carbon dioxide Brayton cycle energy converter coupled to an autonomous lead-cooled fast reactor.

    SciTech Connect

    Moisseytsev, A.; Sienicki, J. J.; Nuclear Engineering Division

    2008-08-01

    The supercritical carbon dioxide (S-CO{sub 2}) Brayton cycle is a promising advanced alternative to the Rankine steam cycle and recuperated gas Brayton cycle for the energy converters of specific reactor concepts belonging to the U.S. Department of Energy Generation IV Nuclear Energy Systems Initiative. A new plant dynamics analysis computer code has been developed for simulation of the S-CO{sub 2} Brayton cycle coupled to an autonomous, natural circulation lead-cooled fast reactor (LFR). The plant dynamics code was used to simulate the whole-plant response to accident conditions. The specific design features of the reactor concept influencing passive safety are discussed and accident scenarios are identified for analysis. Results of calculations of the whole-plant response to loss-of-heat sink, loss-of-load, and pipe break accidents are demonstrated. The passive safety performance of the reactor concept is confirmed by the results of the plant dynamics code calculations for the selected accident scenarios.

  4. Transient Accident Analysis of a Supercritical Carbon Dioxide Brayton Cycle Energy Converter Coupled to an Autonomous Lead-Cooled Fast Reactor

    SciTech Connect

    Moisseytsev, Anton; Sienicki, James J.

    2006-07-01

    The Supercritical Carbon Dioxide (S-CO{sub 2}) Brayton Cycle is a promising advanced alternative to the Rankine saturated steam cycle and recuperated gas Brayton cycle for the energy converters of specific reactor concepts belonging to the U.S. Department of Energy Generation IV Nuclear Energy Systems Initiative. A new plant dynamics analysis computer code has been developed for simulation of the S-CO{sub 2} Brayton cycle coupled to an autonomous, natural circulation Lead-Cooled Fast Reactor (LFR). The plant dynamics code was used to simulate the whole-plant response to accident conditions. The specific design features of the reactor concept influencing passive safety are discussed and accident scenarios are identified for analysis. Results of calculations of the whole-plant response to loss-of-heat sink, loss-of-load, and pipe break accidents are demonstrated. The passive safety performance of the reactor concept is confirmed by the results of the plant dynamics code calculations for the selected accident scenarios. (authors)

  5. Amino-Functionalized Multiwalled Carbon Nanotubes Lead to Successful Ring-Opening Polymerization of Poly(ε-caprolactone): Enhanced Interfacial Bonding and Optimized Mechanical Properties.

    PubMed

    Roumeli, Eleftheria; Papageorgiou, Dimitrios G; Tsanaktsis, Vasilios; Terzopoulou, Zoe; Chrissafis, Konstantinos; Avgeropoulos, Apostolos; Bikiaris, Dimitrios N

    2015-06-03

    In this work, the synthesis, structural characteristics, interfacial bonding, and mechanical properties of poly(ε-caprolactone) (PCL) nanocomposites with small amounts (0.5, 1.0, and 2.5 wt %) of amino-functionalized multiwalled carbon nanotubes (f-MWCNTs) prepared by ring-opening polymerization (ROP) are reported. This method allows the creation of a covalent-bonding zone on the surface of nanotubes, which leads to efficient debundling and therefore satisfactory dispersion and effective load transfer in the nanocomposites. The high covalent grafting extent combined with the higher crystallinity provide the basis for a significant enhancement of the mechanical properties, which was detected in the composites with up to 1 wt % f-MWCNTs. Increasing filler concentration encourages intrinsic aggregation forces, which allow only minor grafting efficiency and poorer dispersion and hence inferior mechanical performance. f-MWCNTs also cause a significant improvement on the polymerization reaction of PCL. Indeed, the in situ polymerization kinetics studies reveal a significant decrease in the reaction temperature, by a factor of 30-40 °C, combined with accelerated the reaction kinetics during initiation and propagation and a drastically reduced effective activation energy.

  6. A sensitive, selective and rapid determination of lead(II) ions in real-life samples using an electrochemically reduced graphene oxide-graphite reinforced carbon electrode.

    PubMed

    Hamsawahini, Kunashegaran; Sathishkumar, Palanivel; Ahamad, Rahmalan; Yusoff, Abdull Rahim Mohd

    2015-11-01

    In this study, a sensitive and cost-effective electrochemically reduced graphene oxide (ErGO) on graphite reinforced carbon (GRC) was developed for the detection of lead (Pb(II)) ions present in the real-life samples. A film of graphene oxide (GO) was drop-casted on GRC and their electrochemical properties were investigated using cyclic voltammetry (CV), amperometry and square wave voltammetry (SWV). Factors influencing the detection of Pb(II) ions, such as grades of GRC, constant applied cathodic potential (CACP), concentration of hydrochloric acid and drop-casting drying time were optimised. GO is irreversibly reduced in the range of -0.7 V to -1.6 V vs Ag/AgCl (3 M) in acidic condition. The results showed that the reduction behaviour of GO contributed to the high sensitivity of Pb(II) ions detection even at nanomolar level. The ErGO-GRC showed the detection limit of 0.5 nM and linear range of 3-15 nM in HCl (1 M). The developed electrode has potential to be a good candidate for the determination of Pb(II) ions in different aqueous system. The proposed method gives a good recovery rate of Pb(II) ions in real-life water samples such as tap water and river water. Copyright © 2015 Elsevier B.V. All rights reserved.

  7. Process development for recovery of lead as lead monoxide from lead-bearing waste

    SciTech Connect

    Xue, Sui; Nesbitt, C.C.

    1996-12-31

    A process has been developed from laboratory-scale experiments for the aqueous processing of various lead-bearing wastes. The process exploits the limited solubility of lead in sulfate-rich solutions to effectively separate lead from other metals. The lead sulfate is then completely converted to lead carbonate using sodium carbonate and ammonium carbonate. The effectiveness of this conversion was observed to be sensitive to the solution pH and carbonate concentration. The final stage of the process uses low temperature calcination of the lead carbonate to form PbO. Yellow lead oxide (massicot) is readily formed if calcination is conducted at a temperature at or above 500{degrees}C, while red lead oxide (litharge) is formed at temperatures near 450{degrees}C. A complete economical analysis of the process will be discussed. 7 refs., 8 figs., 3 tabs.

  8. KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, astronaut Scott E. Parazynski points to the Reinforced Carbon Carbon panels used on the leading edge of the wing of the orbiters. With Parazynski are engineers from around the Agency who are working on improving the RCC panels used on the wing leading edge. The gray carbon composite RCC panels have sufficient strength to withstand the aerodynamic forces experienced during launch and reentry, which can reach as high as 800 pounds per square foot. The operating range of RCC is from minus 250º F to about 3,000º F, the temperature produced by friction with the atmosphere during reentry.

    NASA Image and Video Library

    2003-12-08

    KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, astronaut Scott E. Parazynski points to the Reinforced Carbon Carbon panels used on the leading edge of the wing of the orbiters. With Parazynski are engineers from around the Agency who are working on improving the RCC panels used on the wing leading edge. The gray carbon composite RCC panels have sufficient strength to withstand the aerodynamic forces experienced during launch and reentry, which can reach as high as 800 pounds per square foot. The operating range of RCC is from minus 250º F to about 3,000º F, the temperature produced by friction with the atmosphere during reentry.

  9. KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, astronaut Scott E. Parazynski discusses the Reinforced Carbon Carbon panels used on the leading edge of the wing of the orbiters. With him are engineers from around the Agency who are working on improving the RCC panels used on the wing leading edge. The gray carbon composite RCC panels have sufficient strength to withstand the aerodynamic forces experienced during launch and reentry, which can reach as high as 800 pounds per square foot. The operating range of RCC is from minus 250º F to about 3,000º F, the temperature produced by friction with the atmosphere during reentry.

    NASA Image and Video Library

    2003-12-08

    KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, astronaut Scott E. Parazynski discusses the Reinforced Carbon Carbon panels used on the leading edge of the wing of the orbiters. With him are engineers from around the Agency who are working on improving the RCC panels used on the wing leading edge. The gray carbon composite RCC panels have sufficient strength to withstand the aerodynamic forces experienced during launch and reentry, which can reach as high as 800 pounds per square foot. The operating range of RCC is from minus 250º F to about 3,000º F, the temperature produced by friction with the atmosphere during reentry.

  10. Lead Toxicity

    MedlinePlus

    Agency for Toxic Substances and Disease Registry Case Studies in Environmental Medicine (CSEM) Patient Information Sheet Lead Toxicity What is lead? How are people exposed to lead? • Lead is a soft, blue- ...

  11. Lead Poisoning

    MedlinePlus

    ... high levels of lead in household dust. DRINKING WATER: Lead may get into drinking water when materials used in plumbing materials, such as ... and dishware. Lead may also be in contaminated water. Lead poisoning is harmful to human health and ...

  12. Electrochemical sensors for the simultaneous determination of zinc, cadmium and lead using a Nafion/ionic liquid/graphene composite modified screen-printed carbon electrode.

    PubMed

    Chaiyo, Sudkate; Mehmeti, Eda; Žagar, Kristina; Siangproh, Weena; Chailapakul, Orawon; Kalcher, Kurt

    2016-04-28

    A simple, low cost, and highly sensitive electrochemical sensor, based on a Nafion/ionic liquid/graphene composite modified screen-printed carbon electrode (N/IL/G/SPCE) was developed to determine zinc (Zn(II)), cadmium (Cd(II)), and lead (Pb(II)) simultaneously. This disposable electrode shows excellent conductivity and fast electron transfer kinetics. By in situ plating with a bismuth film (BiF), the developed electrode exhibited well-defined and separate peaks for Zn(II), Cd(II), and Pb(II) by square wave anodic stripping voltammetry (SWASV). Analytical characteristics of the BiF/N/IL/G/SPCE were explored with calibration curves which were found to be linear for Zn(II), Cd(II), and Pb(II) concentrations over the range from 0.1 to 100.0 ng L(-1). With an accumulation period of 120 s detection limits of 0.09 ng mL(-1), 0.06 ng L(-1) and 0.08 ng L(-1) were obtained for Zn(II), Cd(II) and Pb(II), respectively using the BiF/N/IL/G/SPCE sensor, calculated as 3σ value of the blank. In addition, the developed electrode displayed a good repeatability and reproducibility. The interference from other common ions associated with Zn(II), Cd(II) and Pb(II) detection could be effectively avoided. Finally, the proposed analytical procedure was applied to detect the trace metal ions in drinking water samples with satisfactory results which demonstrates the suitability of the BiF/N/IL/G/SPCE to detect heavy metals in water samples and the results agreed well with those obtained by inductively coupled plasma mass spectrometry. Copyright © 2016 Elsevier B.V. All rights reserved.

  13. Ultrasonic assisted dispersive solid-phase microextraction of Eriochrome Cyanine R from water sample on ultrasonically synthesized lead (II) dioxide nanoparticles loaded on activated carbon: Experimental design methodology.

    PubMed

    Bahrani, Sonia; Ghaedi, Mehrorang; Mansoorkhani, Mohammad Javad Khoshnood; Asfaram, Arash; Bazrafshan, Ali Akbar; Purkait, Mihir Kumar

    2017-01-01

    The present research focus on designing an appropriate dispersive solid-phase microextraction (UA-DSPME) for preconcentration and determination of Eriochrome Cyanine R (ECR) in aqueous solutions with aid of sonication using lead (II) dioxide nanoparticles loaded on activated carbon (PbO-NPs-AC). This material was fully identified with XRD and SEM. Influence of pH, amounts of sorbent, type and volume of eluent, and sonication time on response properties were investigated and optimized by central composite design (CCD) combined with surface response methodology using STATISTICA. Among different solvents, dimethyl sulfoxide (DMSO) was selected as an efficient eluent, which its combination by present nanoparticles and application of ultrasound waves led to enhancement in mass transfer. The predicted maximum extraction (100%) under the optimum conditions of the process variables viz. pH 4.5, eluent 200μL, adsorbent dosage 2.5mg and 5min sonication was close to the experimental value (99.50%). at optimum conditions some experimental features like wide 5-2000ngmL(-1) ECR, low detection limit (0.43ngmL(-1), S/N=3:1) and good repeatability and reproducibility (relative standard deviation, <5.5%, n=12) indicate versatility in successful applicability of present method for real sample analysis. Investigation of accuracy by spiking known concentration of ECR over 200-600ngmL(-1) gave mean recoveries from 94.850% to 101.42% under optimal conditions. The procedure was also applied for the pre-concentration and subsequent determination of ECR in tap and waste waters.

  14. Measurements of cross-section of charge current inclusive of antineutrino scattering off nucleons using carbon, iron, lead and scintillator at MINER$\

    SciTech Connect

    Rakotondravohitra, Laza

    2015-08-18

    Neutrino physics is one of the most active fields in the domaine of high energy physics during the last century. The need of precise measurement of neutrino-nucleus interactions required by the neutrino oscillation experiments is a an exiting step. These measurements of cross-section are more than essential for neutrino oscillation experiment. Over the year, many measurements from varieties of experiments have been presented. MINERνA is one of the world leaders in measuring cross-section of neutrino and antineutrino -nucleus interactions. MINERνA is a neutrino-nucleus scattering experiment installed in the few-GeV NuMI beam line at Fermilab. In order to study nuclear dependence, MINERνA is endowed with different types of solid nuclear targets as well are liquid targets such as helium and water. This thesis presents measurements of cross-section of antineutrino scattering off nucleons using a variety of solid nuclear targets, carbon, iron, lead and also polystyrene scintillator (CH). The data set of antineutrino used for this analysis was taken between March and July 2010 with a total of 1.60X1020 protons on target. Charged current inclusive interactions were selected by requiring a positive muon and kinematics limitation of acceptance of the muon spectrometer are applied. The analysis requires neutrino energy between 2GeV et 20GeV and the angle of muon θmu < 17degree . The absolute cross-section # as function of neutrino energy and the differential cross-section dσ/ dxbj measured and shown the corresponding systematics for each nuclear targets. Data results are compared with prediction of the models implemented in the neutrino events generators GENIE 2.6.2 used by the experiment.

  15. Amino and thiol modified magnetic multi-walled carbon nanotubes for the simultaneous removal of lead, zinc, and phenol from aqueous solutions

    NASA Astrophysics Data System (ADS)

    Jiang, Lili; Li, Shujun; Yu, Haitao; Zou, Zongshu; Hou, Xingang; Shen, Fengman; Li, Chuantong; Yao, Xiayan

    2016-04-01

    The novel functionalization of multi-walled carbon nanotubes (MWCNTs) was synthesized by reacting trimethoxysilylpropanethiol (MPTs), hydrazine, ammonium ferrous sulfate, and ammonium ferric sulfate in sequence as efficient ways to introduce Fe3O4, amino and thiol groups onto the nanotubes sidewalls. The magnetic MWCNTs composite material (N2H4-SH-Fe3O4/o-MWCNTs) was characterized by transmission electron microscopy, field emission scanning electron microscopy, X-ray diffraction, thermo-gravimetric analysis, x-ray photoelectron spectroscopy, Fourier transformation infrared spectroscopy and magnetization curve. The results revealed that MPTs and hydrazine were coated on the surface of N2H4-SH-Fe3O4/o-MWCNTs. A series of batch adsorption experiments were conducted to study the experimental conditions, such as pH, contact time, initial concentrations and temperatures, which affected the adsorption process. The adsorption experiment results showed that the maximum equilibrium adsorption capacity of N2H4-SH-Fe3O4/o-MWCNTs for lead, zinc and phenol was 195.81 mg/g, 169.89 mg/g and 38.97 mg/g at pH 6, respectively. The adsorption isotherm was better fitted by the Freundlich model, and the adsorption kinetics was consistent with pseudo-second order kinetics model. Furthermore, thermodynamic data showed that the adsorption process was spontaneous and exothermic. These results indicated that N2H4-SH-Fe3O4/o-MWCNTs may be promising surface modified materials for removing heavy metal ions and phenol from aqueous solutions.

  16. Electrochemical and FTIR studies of the mutual influence of lead(II) or iron(III) and phenol on their adsorption from aqueous acid solution by modified activated carbons.

    PubMed

    Pakuła, M; Walczyk, M; Biniak, S; Swiatkowski, A

    2007-09-01

    Cyclic voltammetry and spectral FTIR studies of the influence of activated carbon surface modification on the co-adsorption of metal cation (lead or iron) and phenol from aqueous acidic solution were carried out. The diversity in surface chemical structure was achieved by applying different procedures of inorganic matter removal and by modifying the carbon samples in various ways: heating under vacuum, aminoxidation in an ammonia-oxygen atmosphere, oxidation with concentrated nitric acid. The quantities of adsorbed metal ions (Pb(2+) or Fe(3+)) and phenol from solutions containing cation or phenol separately or in a mixture were determined. The adsorption capacity from acidic aqueous acidic solution depends on the chemical properties of the activated carbon surface (e.g., decrease in phenol adsorption with relative lower basicity of the adsorbent). The electrochemical parameters of electrodes made from the carbon samples were estimated, and some possible electrochemical reactions were determined from voltammograms recorded in acid electrolyte solution containing adsorbed species (separately or as a mixture). Relationships were found between metal ion adsorption and electrochemical behavior of Pb(2+)/Pb(4+) and Fe(3+)/Fe(2+) couples on the one hand, and the presence of phenol in the solutions tested and the influence of surface chemistry of the carbon electrodes on electrochemical processes on the other. The changes in adsorption capacity with respect to the adsorbates used and the changes in FTIR spectra of the carbons as a result of adsorption and/or coupling phenol molecules are discussed.

  17. Lead Poisoning

    MedlinePlus

    Lead is a metal that occurs naturally in the earth's crust. Lead can be found in all parts of our ... from human activities such as mining and manufacturing. Lead used to be in paint; older houses may ...

  18. Determination of lead(II) sorption capacity of hazelnut shell and activated carbon obtained from hazelnut shell activated with ZnCl2.

    PubMed

    Şencan, Aziz; Karaboyacı, Mustafa; Kılıç, Mehmet

    2015-03-01

    This study aimed to determine the Pb(+2) adsorption capacities of hazelnut shell and activated carbon obtained from hazelnut shell. It also aimed to determine the effect of ZnCl2 in the activation process. The hazelnut was pyrolyzed at 250 and 700 °C. For determining the capture speed of the adsorbents, the pseudo-first- and second-order kinetic studies were performed. The Freundlich and Langmuir isotherm models were used to determine adsorption equilibrium. The surface characterization of hazelnut shell and activated carbon was determined by Brunauer-Emmett-Teller (BET) analysis and FTIR spectrum. Pb(+2) adsorption capacity of obtaining activated carbon was determined by ICP-OES analysis. The raw hazelnut shell's BET surface area is 5.92 m(2)/g and the surface area of activated carbons which is pyrolyzed at 250 and 700 °C were determined (270.2 and 686.7 m(2)/g, respectively. The surface area of hazelnut shell, which pyrolyzed at 700 °C after being activated with ZnCl2, was determined to be 736.49 m(2)/g. Results show that physical adsorption process is dominant for the activated carbon pyrolysis at 700 °C but the chemical adsorption is dominant for the activated carbon pyrolysis at lower degrees and for raw hazelnut shell.

  19. Understanding the function and performance of carbon-enhanced lead-acid batteries : milestone report for the DOE Energy Storage Systems Program (FY11 Quarter 4: July through September 2011).

    SciTech Connect

    Ferreira, Summer Rhodes; Shane, Rodney; Enos, David George

    2011-10-01

    This report describes the status of research being performed under CRADA No. SC10/01771.00 (Lead/Carbon Functionality in VRLA Batteries) between Sandia National Laboratories and East Penn Manufacturing, conducted for the U.S. Department of Energy's Energy Storage Systems Program. The Quarter 4 Milestone was completed on time. The milestone entails the initiation of high rate, partial state of charge (HRPSoC) cycling of the carbon enhanced batteries. The morphology, porosity, and porosity distribution within the plates after 1k and 10k cycles were documented, illustrating the changes which take place in the early life of the carbon containing batteries, and as the battery approaches failure due to hard sulfation for the control battery. Longer term cycling on a subset of the received East Penn cells containing different carbons (and a control) continues, and will progress into FY12. Carbon has been explored as an addition to lead-acid battery electrodes in a number of ways. Perhaps the most notable to date has been the hybrid 'Ultrabattery' developed by CSIRO where an asymmetric carbon-based electrochemical capacitor is combined with a lead-acid battery into a single cell, dramatically improving high-rate partial-state-of-charge (HRPSoC) operation. As illustrated below, the 'Ultrabattery' is a hybrid device constructed using a traditional lead-acid battery positive plate (i.e., PbO2) and a negative electrode consisting of a carbon electrode in parallel with a lead-acid negative plate. This device exhibits a dramatically improved cycle life over traditional VRLA batteries, as well as increased charge power and charge acceptance. The 'Ultrabattery' has been produced successfully by both The Furukawa Battery Co. and East Penn Manufacturing. An example illustrating the dramatic improvement in cycle life of the Ultrabattery over a conventional VRLA battery is shown in a graph. In addition to the aforementioned hybrid device, carbon has also been added directly to

  20. Understanding the function and performance of carbon-enhanced lead-acid batteries : milestone report for the DOE energy storage systems program (FY11 Quarter 3: April through June 2011).

    SciTech Connect

    Ferreira, Summer Rhodes; Shane, Rodney; Enos, David George

    2011-09-01

    This report describes the status of research being performed under CRADA No. SC10/01771.00 (Lead/Carbon Functionality in VRLA Batteries) between Sandia National Laboratories and East Penn Manufacturing, conducted for the U.S. Department of Energy's Energy Storage Systems Program. The Quarter 3 Milestone was completed on time. The milestone entails an ex situ analysis of a control as well as three carbon-containing negative plates in the raw, as cast form as well as after formation. The morphology, porosity, and porosity distribution within each plate was evaluated. In addition, baseline electrochemical measurements were performed on each battery to establish their initial performance. These measurements included capacity, internal resistance, and float current. The results obtained for the electrochemical testing were in agreement with previous evaluations performed at East Penn manufacturing. Cycling on a subset of the received East Penn cells containing different carbons (and a control) has been initiated.

  1. Lead poisoning

    SciTech Connect

    Rekus, J.F.

    1992-08-01

    Construction workers who weld, cut or blast structural steel coated with lead-based paint are at significant risk of lead poisoning. Although technology to control these exposures may not have existed when the lead standard was promulgated, it is available today. Employers who do not take steps to protect their employees from lead exposure may be cited and fined severely for their failure.

  2. The overexpression of the pine transcription factor PpDof5 in Arabidopsis leads to increased lignin content and affects carbon and nitrogen metabolism.

    PubMed

    Rueda-López, Marina; Cañas, Rafael A; Canales, Javier; Cánovas, Francisco M; Ávila, Concepción

    2015-12-01

    PpDof 5 is a regulator of the expression of glutamine synthetase (GS; EC 6.3.1.2) genes in photosynthetic and non-photosynthetic tissues of maritime pine. We have used Arabidopsis thaliana as a model system to study PpDof 5 function in planta, generating transgenic lines overexpressing the pine transcription factor. The overexpression of PpDof 5 resulted in a substantial increase of lignin content with a simultaneous regulation of carbon and nitrogen key genes. In addition, partitioning in carbon and nitrogen compounds was spread via various secondary metabolic pathways. These results suggest pleiotropic effects of PpDof 5 expression on various metabolic pathways of carbon and nitrogen metabolism. Plants overexpressing PpDof 5 exhibited upregulation of genes encoding enzymes for sucrose and starch biosynthesis, with a parallel increase in the content of soluble sugars. When the plants were grown under nitrate as the sole nitrogen source, they exhibited a significant regulation of the expression of genes involved mainly in signaling, but similar growth rates to wild-type plants. However, plants grown under ammonium exhibited major induction of the expression of photosynthetic genes and differential expression of ammonium and nitrate transporters. All these data suggest that in addition to controlling ammonium assimilation, PpDof 5 could be also involved in the regulation of other pathways in carbon and nitrogen metabolism in pine trees.

  3. Lead Test

    MedlinePlus

    ... the condition. Children should also be assessed for iron deficiency and general nutrition consistent with AAP guidelines. BLLs ... raised blood lead concentrations should be tested for iron deficiency . Each person eliminates lead differently. Thus, laboratory tests ...

  4. Lead Poisoning

    MedlinePlus

    ... through deteriorating paint, household dust, bare soil, air, drinking water, food, ceramics, home remedies, hair dyes and other ... an elevated blood lead level can easily result. Drinking water can also sometimes contribute to elevated blood lead ...

  5. On-line separation and preconcentration of lead(II) by solid-phase extraction using activated carbon loaded with xylenol orange and its determination by flame atomic absorption spectrometry.

    PubMed

    Ensafi, Ali A; Shiraz, A Zendegi

    2008-02-11

    Activated carbon loaded with xylenol orange in a mini-column was used for the highly selective separation and preconcentration of Pb(II) ions. An on-line system for enrichment and the determination of Pb(II) was carried out on flame atomic absorption spectrometry. The conditions of preconcentration and quantitative recovery of Pb(II) from diluted solution, such as pH of aqueous phase, amount of the sorbent, volume of the solutions and flow variables were studied as well as effect of potential interfering ions. Under the optimum conditions, Pb(II) in an aqueous sample was concentrated about 200-fold and the detection limit was 0.4 ng mL(-1) Pb(II). The adsorption capacity of the solid phase was 0.20mg of lead per one gram of the modified activated carbon. The modified activated carbon is stable for several treatments of sample solutions without the need for using any chemical reagent. The recovery of lead(II) from river water, waste water, tap water, and in the following reference materials: SRM 2711 Montana soil and GBW-07605 tea were obtained in the range of 97-104% by the proposed method.

  6. Lead Pencils

    NASA Technical Reports Server (NTRS)

    Gray, L. B.

    1971-01-01

    A study, undertaken to determine the lead content of paint on various pencils in the Goddard supply system, is reported. The survey found that lead content varied from .04 mg per pencil for carmine colored pencils to approximately 43 mg per pencil for yellow colored pencils. Results also show that yellow pencils had higher lead content than other colors analyzed. More detailed results are given in tabular form.

  7. Did a drought crisis lead to cultural changes in Eolian Islands during the Bronze Age? New data from archaeological excavations and carbon isotopes analysis of archaeobotanical remains

    NASA Astrophysics Data System (ADS)

    Fiorentino, Girolamo; Caracuta, Valentina; Martinelli, Maria Clara; Quarta, Gianluca; Calcagnile, Lucio

    2010-05-01

    Agricultural potential is commonly regarded as a key factor for the development of pre-modern complex societies in Mediterranean regions. For this reason, the assessment of paleo-rainfall regimes is considered fundamental to understand the influence of short-term climate fluctuations on ancient human communities, especially in those areas characterised by critical environmental conditions such as Eolian archipelagos. Usually, plant remains in archaeological contexts are used to assess agricultural practices and any strategies adopted by ancient populations to face climate changes. Within this work we intend to extend the traditional archaeobotanical approach by using carbon isotope analysis of ancient plant remains in order to infer paleorainfall trends. For this purpose fourty samples of plant remains recovered from Bronze Age archaeological contexts recently excavated in Filicudi and Salina islands, Eolian archipelagos, were selected to be submitted to AMS (Accelerator Mass Spectrometry) radiocarbon dating, archaeobotanaical and carbon stable isotopes analyses. This approach allowed the reconstruction in the analyzed samples of the variation of the carbon isotope composition, expressed through the δ13C term, in a diachronic scale as obtained by the combined radiocarbon dating analyses performed on the same archaeological material. The obtained results show clear chronological pattern of variation of the δ13C term in the plant tissues which find correspondence with other climatic proxy records and from which paleoclimatic information have been inferred. From the archaeological point of view, the obtained results allow the evaluation of the influence of climate on the dynamics of population of Eolian island by reconsidering archaeological indicators coming from the recent excavations carried out in the sites of Filicudi and Salina.

  8. Leading Democratically

    ERIC Educational Resources Information Center

    Brookfield, Stephen

    2010-01-01

    Democracy is the most venerated of American ideas, the one for which wars are fought and people die. So most people would probably agree that leaders should be able to lead well in a democratic society. Yet, genuinely democratic leadership is a relative rarity. Leading democratically means viewing leadership as a function or process, rather than…

  9. Multi-walled carbon nanotubes and metal-organic framework nanocomposites as novel hybrid electrode materials for the determination of nano-molar levels of lead in a lab-on-valve format.

    PubMed

    Wang, Yang; Wu, Yichun; Xie, Jing; Ge, Huali; Hu, Xiaoya

    2013-09-07

    Metal-organic frameworks have been the subject of intense research because of their unique physicochemical properties. The presented study investigates the application of multi-wall carbon nanotubes and metal-organic frameworks (MWCNTs@Cu3(BTC)2) nanoparticles-modified electrode for the determination of trace levels of lead. The nanocomposites were prepared by solvothermal synthesis and characterized in detail. The experimental procedure was carried out by accumulating lead on the electrode surface and subsequently measuring with differential pulse anodic stripping voltammetry in a lab-on-valve format. The main parameters affecting the analytical performance, including the amount of MWCNTs@Cu3(BTC)2 suspension, supporting electrolyte and its pH, stripping mode, and flow rate, have been investigated in detail. Under the optimum conditions, the oxidation peak current displayed a calibration response for lead over a concentration range from 1.0 × 10(-9) to 5.0 × 10(-8) mol L(-1) with a excellent detection limit of 7.9 × 10(-10) mol L(-1). The relative standard deviation of 7 successive scans was 3.10% for 1.0 × 10(-8) mol L(-1) lead. The established method showed a great improvement in sensitivity and sample throughput for lead analysis.

  10. Tuning the Composition of Electrodeposited Bimetallic Tin-Lead Catalysts for Enhanced Activity and Durability in Carbon Dioxide Electroreduction to Formate.

    PubMed

    Moore, Colin E; Gyenge, Előd L

    2017-09-11

    Bimetallic Sn-Pb catalysts with five different Sn/Pb atomic ratios were electrodeposited on Teflonated carbon paper and non-Teflonated carbon cloth using both fluoroborate- and oxide-containing deposition media to produce catalysts for the electrochemical reduction of CO2 (ERC) to formate (HCOO(-) ). The interaction between catalyst composition, morphology, substrate, and deposition media was investigated by using cyclic voltammetry and constant potential electrolysis at -2.0 V versus Ag/AgCl for 2 h in 0.5 m KHCO3 . The catalysts were analyzed before and after electrolysis by using SEM and XRD to determine the mechanisms of Faradaic efficiency loss and degradation. Catalysts that are mainly Sn with 15-35 at % Pb generated Faradaic efficiencies up to 95 % with a stable performance. However, pure Sn catalysts showed high initial stage formate production rates but experienced an extensive (up to 30 %) decrease of the Faradaic efficiency. The XRD results demonstrated the presence of polycrystalline SnO2 after electrolysis using Sn-Pb catalysts with 35 at % Pb and its absence in the case of pure Sn. It is proposed that the presence of Pb (15-35 at %) in mainly Sn catalysts stabilized SnO2 , which is responsible for the enhanced Faradaic efficiency and catalytic durability in the ERC. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. A dual-targeted purple acid phosphatase in Arabidopsis thaliana moderates carbon metabolism and its overexpression leads to faster plant growth and higher seed yield.

    PubMed

    Sun, Feng; Suen, Pui Kit; Zhang, Youjun; Liang, Chao; Carrie, Chris; Whelan, James; Ward, Jane L; Hawkins, Nathaniel D; Jiang, Liwen; Lim, Boon Leong

    2012-04-01

    • Overexpression of AtPAP2, a purple acid phosphatase (PAP) with a unique C-terminal hydrophobic motif in Arabidopsis, resulted in earlier bolting and a higher seed yield. Metabolite analysis showed that the shoots of AtPAP2 overexpression lines contained higher levels of sugars and tricarboxylic acid (TCA) metabolites. Enzyme assays showed that sucrose phosphate synthase (SPS) activity was significantly upregulated in the overexpression lines. The higher SPS activity arose from a higher level of SPS protein, and was independent of SnRK1. • AtPAP2 was found to be targeted to both plastids and mitochondria via its C-terminal hydrophobic motif. Ectopic expression of a truncated AtPAP2 without this C-terminal motif in Arabidopsis indicated that the subcellular localization of AtPAP2 is essential for its biological actions. • Plant PAPs are generally considered to mediate phosphorus acquisition and redistribution. AtPAP2 is the first PAP shown to modulate carbon metabolism and the first shown to be dual-targeted to both plastids and mitochondria by a C-terminal targeting signal. • One PAP-like sequence carrying a hydrophobic C-terminal motif could be identified in the genome of the smallest free-living photosynthetic eukaryote, Ostreococcus tauri. This might reflect a common ancestral function of AtPAP2-like sequences in the regulation of carbon metabolism. © 2012 The Authors. New Phytologist © 2012 New Phytologist Trust.

  12. Direct extraction of lead (II) from untreated human blood serum using restricted access carbon nanotubes and its determination by atomic absorption spectrometry.

    PubMed

    Barbosa, Valéria Maria Pereira; Barbosa, Adriano Francisco; Bettini, Jefferson; Luccas, Pedro Orival; Figueiredo, Eduardo Costa

    2016-01-15

    Oxidized carbon nanotubes were covered with layers of bovine serum albumin to result in so-called restricted-access carbon nanotubes (RACNTs). This material can extract Pb(2+) ions directly from untreated human blood serum while excluding all the serum proteins. The RACNTs have a protein exclusion capacity of almost 100% and a maximum Pb(2+) adsorption capacity of 34.5mg g(-1). High resolution transmission electron microscopy, scanning transmission electron microscopy and energy dispersive spectroscopy were used to confirm the BSA layer and Pb(2+) adsorption sites. A mini-column filled with RACNTs was used in an on-line solid phase extraction system coupled to a thermospray flame furnace atomic absorption spectrometry. At optimized experimental conditions, the method has a detection limit as low as 2.1µg L(-1), an enrichment factor of 5.5, and inter- and intra-day precisions (expressed as relative standard deviation) of <8.1%. Recoveries of the Pb(2+) spiked samples ranged from 89.4% to 107.3% for the extraction from untreated human blood serum.

  13. Solubility of lead and copper in biochar-amended small arms range soils: influence of soil organic carbon and pH.

    PubMed

    Uchimiya, Minori; Bannon, Desmond I

    2013-08-14

    Biochar is often considered a strong heavy metal stabilizing agent. However, biochar in some cases had no effects on, or increased the soluble concentrations of, heavy metals in soil. The objective of this study was to determine the factors causing some biochars to stabilize and others to dissolve heavy metals in soil. Seven small arms range soils with known total organic carbon (TOC), cation exchange capacity, pH, and total Pb and Cu contents were first screened for soluble Pb and Cu concentrations. Over 2 weeks successive equilibrations using weak acid (pH 4.5 sulfuric acid) and acetate buffer (0.1 M at pH 4.9), Alaska soil containing disproportionately high (31.6%) TOC had nearly 100% residual (insoluble) Pb and Cu. This soil was then compared with sandy soils from Maryland containing significantly lower (0.5-2.0%) TOC in the presence of 10 wt % (i) plant biochar activated to increase the surface-bound carboxyl and phosphate ligands (PS450A), (ii) manure biochar enriched with soluble P (BL700), and (iii) unactivated plant biochars produced at 350 °C (CH350) and 700 °C (CH500) and by flash carbonization (corn). In weak acid, the pH was set by soil and biochar, and the biochars increasingly stabilized Pb with repeated extractions. In pH 4.9 acetate buffer, PS450A and BL700 stabilized Pb, and only PS450A stabilized Cu. Surface ligands of PS450A likely complexed and stabilized Pb and Cu even under acidic pH in the presence of competing acetate ligand. Oppositely, unactivated plant biochars (CH350, CH500, and corn) mobilized Pb and Cu in sandy soils; the putative mechanism is the formation of soluble complexes with biochar-borne dissolved organic carbon. In summary, unactivated plant biochars can inadvertently increase dissolved Pb and Cu concentrations of sandy, low TOC soils when used to stabilize other contaminants.

  14. Lead poisoning

    MedlinePlus

    ... help if this information is not immediately available. Poison Control If someone has severe symptoms from possible ... be caused by lead poisoning, call your local poison control center. Your local poison center can be ...

  15. Development of a plant dynamics computer code for analysis of a supercritical carbon dioxide Brayton cycle energy converter coupled to a natural circulation lead-cooled fast reactor.

    SciTech Connect

    Moisseytsev, A.; Sienicki, J. J.

    2007-03-08

    STAR-LM is a lead-cooled pool-type fast reactor concept operating under natural circulation of the coolant. The reactor core power is 400 MWt. The open-lattice core consists of fuel pins attached to the core support plate, (the does not consist of removable fuel assemblies). The coolant flows outside of the fuel pins. The fuel is transuranic nitride, fabricated from reprocessed LWR spent fuel. The cladding material is HT-9 stainless steel; the steady-state peak cladding temperature is 650 C. The coolant is single-phase liquid lead under atmospheric pressure; the core inlet and outlet temperatures are 438 C and 578 C, respectively. (The Pb coolant freezing and boiling temperatures are 327 C and 1749 C, respectively). The coolant is contained inside of a reactor vessel. The vessel material is Type 316 stainless steel. The reactor is autonomous meaning that the reactor power is self-regulated based on inherent reactivity feedbacks and no external power control (through control rods) is utilized. The shutdown (scram) control rods are used for startup and shutdown and to stop the fission reaction in case of an emergency. The heat from the reactor is transferred to the S-CO{sub 2} Brayton cycle in in-reactor heat exchangers (IRHX) located inside the reactor vessel. The IRHXs are shell-and-tube type heat exchangers with lead flowing downwards on the shell side and CO{sub 2} flowing upwards on the tube side. No intermediate circuit is utilized. The guard vessel surrounds the reactor vessel to contain the coolant, in the very unlikely event of reactor vessel failure. The Reactor Vessel Auxiliary Cooling System (RVACS) implementing the natural circulation of air flowing upwards over the guard vessel is used to cool the reactor, in the case of loss of normal heat removal through the IRHXs. The RVACS is always in operation. The gap between the vessels is filled with liquid lead-bismuth eutectic (LBE) to enhance the heat removal by air by significantly reducing the thermal

  16. A sucrose-binding site provides a lead towards an isoform-specific inhibitor of the cancer-associated enzyme carbonic anhydrase IX

    DOE PAGES

    Pinard, Melissa A.; Aggarwal, Mayank; Mahon, Brian P.; ...

    2015-09-23

    Human carbonic anhydrase (CA; EC 4.2.1.1) isoform IX (CA IX) is an extracellular zinc metalloenzyme that catalyzes the reversible hydration of CO2to HCO3$-$, thereby playing a role in pH regulation. The majority of normal functioning cells exhibit low-level expression of CA IX. However, in cancer cells CA IX is upregulated as a consequence of a metabolic transition known as the Warburg effect. The upregulation of CA IX for cancer progression has drawn interest in it being a potential therapeutic target. CA IX is a transmembrane protein, and its purification, yield and crystallization have proven challenging to structure-based drug design, whereasmore » the closely related cytosolic soluble isoform CA II can be expressed and crystallized with ease. Therefore, we have utilized structural alignments and site-directed mutagenesis to engineer a CA II that mimics the active site of CA IX. In this paper, the X-ray crystal structure of this CA IX mimic in complex with sucrose is presented and has been refined to a resolution of 1.5 Å, anRcryst of 18.0% and anRfree of 21.2%. Finally, the binding of sucrose at the entrance to the active site of the CA IX mimic, and not CA II, in a non-inhibitory mechanism provides a novel carbohydrate moiety binding site that could be further exploited to design isoform-specific inhibitors of CA IX.« less

  17. ZnO-Decorated Carbon Nanotube Hybrids as Fillers Leading to Reversible Nonlinear I-V Behavior of Polymer Composites for Device Protection.

    PubMed

    Yang, Wenhu; Wang, Jian; Luo, Suibin; Yu, Shuhui; Huang, Haitao; Sun, Rong; Wong, Ching-Ping

    2016-12-28

    Overvoltage protection is becoming increasingly important because of miniaturization and multifunctionality of electronic devices. Flexible, easily processable materials with nonlinear and reversible I-V behavior are highly desired. In this study, hybrid nanoparticles of ZnO-decorated carbon nanotubes (CNT-ZnO) were synthesized via a sol-gel hydrothermal process employed in an epoxy matrix to prepare composites. Microstructure analysis demonstrated that ZnO nanoparticles were well-bonded to the surface of CNT. The CNT-ZnO/epoxy composites exhibited nonlinear I-V behavior under increasingly applied voltage with a nonlinear coefficient of 5.01 (10 wt % filler loading). More importantly, the composites possessed excellent reversibility from dielectric to conductor and vise versa in the recycling of increase and decrease of applied electric field, in contrast to the poor recoverability of pure CNT-filled epoxy. The mechanism of the nonlinear I-V behavior and reversibility was investigated and discussed. A simple circuit was fabricated, which verified well the protection function of the CNT-ZnO/polymer composites.

  18. A sucrose-binding site provides a lead towards an isoform-specific inhibitor of the cancer-associated enzyme carbonic anhydrase IX

    PubMed Central

    Pinard, Melissa A.; Aggarwal, Mayank; Mahon, Brian P.; Tu, Chingkuang; McKenna, Robert

    2015-01-01

    Human carbonic anhydrase (CA; EC 4.2.1.1) isoform IX (CA IX) is an extracellular zinc metalloenzyme that catalyzes the reversible hydration of CO2 to HCO3 −, thereby playing a role in pH regulation. The majority of normal functioning cells exhibit low-level expression of CA IX. However, in cancer cells CA IX is upregulated as a consequence of a metabolic transition known as the Warburg effect. The upregulation of CA IX for cancer progression has drawn interest in it being a potential therapeutic target. CA IX is a transmembrane protein, and its purification, yield and crystallization have proven challenging to structure-based drug design, whereas the closely related cytosolic soluble isoform CA II can be expressed and crystallized with ease. Therefore, we have utilized structural alignments and site-directed mutagenesis to engineer a CA II that mimics the active site of CA IX. In this paper, the X-ray crystal structure of this CA IX mimic in complex with sucrose is presented and has been refined to a resolution of 1.5 Å, an R cryst of 18.0% and an R free of 21.2%. The binding of sucrose at the entrance to the active site of the CA IX mimic, and not CA II, in a non-inhibitory mechanism provides a novel carbohydrate moiety binding site that could be further exploited to design isoform-specific inhibitors of CA IX. PMID:26457530

  19. Chemical and enzymological characterization of an Indonesian variant of human erythrocyte carbonic anhydrase II, CAII Jogjakarta (17 Lys leads to Glu).

    PubMed

    Jones, G L; Sofro, A S; Shaw, D C

    1982-10-01

    A new variant of human erythrocyte carbonic anhydrase II (CAII) was discovered in a single heterozygous individual during routine screening of blood samples from the island of Java in Indonesia. The normal and variant components of the heterozygous CAII mixture were resolved by isoelectric focusing following purification by a specific affinity matrix. Specific esterase activities and Michaelis-Menten constants were identical. Only very small differences were noted with respect to inhibition by acetazolamide and chloride. Double diffusion analysis showed the immunological identify of the normal and variant enzymes. The variant CAII was considerably less heat stable than the normal enzyme. The variant was slightly more stable than the normal enzyme upon dialysis against the zinc chelator dipicolinic acid (PDCA), indicating a tighter binding of zinc than the normal enzyme. Analysis of tryptic peptides from the normal and variant enzymes indicated that, in the variant, lysine at position 17 from the N terminus had changed to glutamic acid. The differences in physiochemical properties observed for the normal and variant enzyme are discussed in relation to the possible effects of this substitution on the structure of the CAII molecule.

  20. Recovery of lead from lead paste in spent lead acid battery by hydrometallurgical desulfurization and vacuum thermal reduction.

    PubMed

    Ma, Yunjian; Qiu, Keqiang

    2015-06-01

    Lead sulfate, lead oxides and lead metal are the main component of lead paste in spent lead acid battery. When lead sulfate was desulfurized and transformed into lead carbonate by sodium carbonate, lead metal and lead oxides remained unchanged. Lead carbonate is easily decomposed to lead oxide and carbon dioxide under high temperature. Namely, vacuum thermal process is the reduction reaction of lead oxides. A compatible environmental process consisted of hydrometallurgical desulfurization and vacuum thermal reduction to recycle lead was investigated in this research. Lead paste was firstly desulfurized with sodium carbonate, by which, the content of sulfur declined from 7.87% to 0.26%. Then, the desulfurized lead paste was reduced by charcoal under vacuum. Under the optimized reaction conditions, i.e., vacuum thermal reduction at temperature 850°C under 20 Pa for 45 min, a 22.11×10(-2) g cm(-2) min(-1) reduction rate, and a 98.13% direct recovery ratio of fine lead (99.77%) had been achieved, respectively.

  1. Ecotoxicology: Lead

    USGS Publications Warehouse

    Scheuhammer, A.M.; Beyer, W.N.; Schmitt, C.J.; Jorgensen, Sven Erik; Fath, Brian D.

    2008-01-01

    Lead (Pb) is a naturally occurring metallic element; trace concentrations are found in all environmental media and in all living things. However, certain human activities, especially base metal mining and smelting; combustion of leaded gasoline; the use of Pb in hunting, target shooting, and recreational angling; the use of Pb-based paints; and the uncontrolled disposal of Pb-containing products such as old vehicle batteries and electronic devices have resulted in increased environmental levels of Pb, and have created risks for Pb exposure and toxicity in invertebrates, fish, and wildlife in some ecosystems.

  2. Leading Meetings.

    ERIC Educational Resources Information Center

    Lindelow, John; Heynderickx, James

    Chapter 13 of a revised volume on school leadership, this chapter offers suggestions to help educators improve their performance in meetings, both as group leaders and as participants. Well-run meetings can rejuvenate an organization, leading to improved teamwork, communication, and morale. A poor meeting, on the other hand, can have a…

  3. Tetraethyl lead

    Integrated Risk Information System (IRIS)

    Tetraethyl lead ; CASRN 78 - 00 - 2 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Ef

  4. Heterologous expression of yeast Hxt2 in Arabidopsis thaliana alters sugar uptake, carbon metabolism and gene expression leading to glucose tolerance of germinating seedlings.

    PubMed

    Padilla-Chacón, Daniel; Cordoba, Elizabeth; Olivera, Teresa; Sánchez, Sobeida; Coello, Patricia; León, Patricia; Tiessen, Axel; Martínez-Barajas, Eleazar

    2010-04-01

    The hexose transporter 2 gene (Hxt2) from Saccharomyces cerevisiae was expressed in Arabidopsis thaliana under control of the 35S promoter. Several independent transgenic lines were selected after confirming single gene insertion by southern blot analysis in the T4 generation. Northern blots revealed the presence of heterologous transcript. Radiolabeling experiments revealed an increased rate of incorporation of the non-metabolizable analog 3-O-methyl-[U-14C]-glucose. This confirmed that the yeast Hxt2 transporter was functional in Arabidopsis. No phenotypic changes at the vegetative and reproductive stages could be detected in the transgenic lines when compared to wild type plants. Shortly after germination some differences in development and glucose signaling were observed. Transgenic seedlings cultivated in liquid medium or on solid agar plates were able to grow with 3% glucose (producing bigger plants and longer roots), while development of wild type plants was delayed under those conditions. Metabolite analysis revealed that the Hxt2 transgenic lines had higher rates of sugar utilization. Transcriptional profiling showed that particular genes were significantly up- or down-regulated. Some transcription factors like At1g27000 were repressed, while others, such as At3g58780, were induced. The mRNA from classical sugar signaling genes such as STP1, Hxk1, and ApL3 behaved similarly in transgenic lines and wild type lines. Results suggest that the Hxt2 transgene altered some developmental processes related to the perception of high carbon availability after the germination stage. We conclude that the developmental arrest of wild type plants at 3% glucose not only depends on Hxk1 as the only sugar sensor but might also be influenced by the route of hexose transport across the plasma membrane.

  5. A sucrose-binding site provides a lead towards an isoform-specific inhibitor of the cancer-associated enzyme carbonic anhydrase IX

    SciTech Connect

    Pinard, Melissa A.; Aggarwal, Mayank; Mahon, Brian P.; Tu, Chingkuang; McKenna, Robert

    2015-09-23

    Human carbonic anhydrase (CA; EC 4.2.1.1) isoform IX (CA IX) is an extracellular zinc metalloenzyme that catalyzes the reversible hydration of CO2to HCO3$-$, thereby playing a role in pH regulation. The majority of normal functioning cells exhibit low-level expression of CA IX. However, in cancer cells CA IX is upregulated as a consequence of a metabolic transition known as the Warburg effect. The upregulation of CA IX for cancer progression has drawn interest in it being a potential therapeutic target. CA IX is a transmembrane protein, and its purification, yield and crystallization have proven challenging to structure-based drug design, whereas the closely related cytosolic soluble isoform CA II can be expressed and crystallized with ease. Therefore, we have utilized structural alignments and site-directed mutagenesis to engineer a CA II that mimics the active site of CA IX. In this paper, the X-ray crystal structure of this CA IX mimic in complex with sucrose is presented and has been refined to a resolution of 1.5 Å, anRcryst of 18.0% and anRfree of 21.2%. Finally, the binding of sucrose at the entrance to the active site of the CA IX mimic, and not CA II, in a non-inhibitory mechanism provides a novel carbohydrate moiety binding site that could be further exploited to design isoform-specific inhibitors of CA IX.

  6. Detection of Lead in the Carbon-rich, Very Metal-poor Star LP 625-44: A Strong Constraint on s-Process Nucleosynthesis at Low Metallicity.

    PubMed

    Aoki; Norris; Ryan; Beers; Ando

    2000-06-20

    We report the detection of the Pb i lambda4057.8 line in the very metal-poor (&sqbl0;Fe&solm0;H&sqbr0;=-2.7), carbon-rich star, LP 625-44. We determine the abundance of Pb (&sqbl0;Pb&solm0;Fe&sqbr0;=2.65) and 15 other neutron-capture elements. The abundance pattern between Ba and Pb agrees well with a scaled solar system s-process component, while the lighter elements (Sr-Zr) are less abundant than Ba. The enhancement of s-process elements is interpreted as a result of mass transfer in a binary system from a previous asymptotic giant branch (AGB) companion, an interpretation strongly supported by radial velocity variations of this system. The detection of Pb makes it possible, for the first time, to compare model predictions of s-process nucleosynthesis in AGB stars with observations of elements between Sr and Pb. The Pb abundance is significantly lower than the prediction of recent models (e.g., Gallino et al.), which succeeded in explaining the metallicity dependence of the abundance ratios of light s-elements (Sr-Zr) to heavy ones (Ba-Dy) found in previously observed s-process-enhanced stars. This suggests that one should either (1) reconsider the underlying assumptions concerning the (13)C-rich s-processing site ((13)C pocket) in the present models or (2) investigate alternative sites of s-process nucleosynthesis in very metal-poor AGB stars.

  7. Determination of cadmium and lead in urine samples after dispersive solid-liquid extraction on multiwalled carbon nanotubes by slurry sampling electrothermal atomic absorption spectrometry

    NASA Astrophysics Data System (ADS)

    Álvarez Méndez, J.; Barciela García, J.; García Martín, S.; Peña Crecente, R. M.; Herrero Latorre, C.

    2015-04-01

    A new method for the determination of Cd and Pb in urine samples has been developed. The method involves dispersive solid-phase extraction (DSPE), slurry sampling (SS), and subsequent electrothermal atomic absorption spectrometry (ETAAS). Oxidized multiwalled carbon nanotubes (MWCNTs) were used as the sorbent material. The isolated MWCNT/analyte aggregates were treated with nitric acid to form a slurry and both metals were determined directly by injecting the slurry into the ETAAS-atomizer. The parameters that influence the adsorption of the metals on MWCNTs in the DSPE process, the formation and extraction of the slurry, and the ETAAS conditions were studied by different factorial design strategies. The detection and quantification limits obtained for Cd under optimized conditions were 9.7 and 32.3 ng L- 1, respectively, and for Pb these limits were 0.13 and 0.43 μg L- 1. The preconcentration factors achieved were 3.9 and 5.4. The RSD values (n = 10) were less than 4.1% and 5.9% for Cd and Pb, respectively. The accuracy of the method was assessed in recovery studies, with values in the range 96-102% obtained for Cd and 97-101% for Pb. In addition, the analysis of certified reference materials gave consistent results. The DSPE-SS-ETAAS method is a novel and useful strategy for the determination of Pb and Cd at low levels in human urine samples. The method is sensitive, fast, and free of matrix interferences, and it avoids the tedious and time-consuming on-column adsorption and elution steps associated with commonly used SPE procedures. The proposed method was used to determine Cd and Pb in urine samples of unexposed healthy people and satisfactory results were obtained.

  8. Methanothermal treatment of carbonated mixtures of PbSO4 and PbO2 to synthesize α-PbO for lead acid batteries

    NASA Astrophysics Data System (ADS)

    Gao, Pengran; Lv, Weixin; Zhang, Rui; Liu, Yi; Li, Guanghua; Bu, Xianfu; Lei, Lixu

    2014-02-01

    We have developed a novel route to make new batteries from spent ones, in which we obtain and regenerate the active materials of positive electrode and negative electrode respectively. For the spent lead acid batteries, the positive electrode active materials contain both PbSO4 and PbO2. To make full use of them, we have to investigate the treatment of the mixtures rather than only PbO2, which we have reported previously. Here we report our investigation on three mixtures of PbSO4 and PbO2 in different mole ratios, as well as the electrode materials directly from the spent batteries. The mixtures are firstly desulphated, and then solvothermally processed in methanol at 140 °C for 24 h. The as-obtained solids contain both PbO·PbCO3 and PbCO3, which have been calcined to form α-PbO. The α-PbO powders are similar irregular particles and highly electrochemically active, which discharge around 170 mAh g-1 at 5 mA g-1, 80 mAh g-1 at 200 mA g-1 and 60 mAh g-1 at 400 mA g-1 with excellent cyclic stability in 50 cycles.

  9. Simultaneous determination of zinc, copper, lead, and cadmium in fuel ethanol by anodic stripping voltammetry using a glassy carbon-mercury-film electrode.

    PubMed

    De Oliveira, Marcelo Firmino; Saczk, Adelir Aparecida; Okumura, Leonardo Luiz; Fernandes, Andréa Pires; De Moraes, Mercedes; Stradiotto, Nelson Ramos

    2004-09-01

    A new, versatile, and simple method for quantitative analysis of zinc, copper, lead, and cadmium in fuel ethanol by anodic stripping voltammetry is described. These metals can be quantified by direct dissolution of fuel ethanol in water and subsequent voltammetric measurement after the accumulation step. A maximum limit of 20% ( v/ v) ethanol in water solution was obtained for voltammetric measurements without loss of sensitivity for metal species. Chemical and operational optimum conditions were analyzed in this study; the values obtained were pH 2.9, a 4.7-microm thickness mercury film, a 1,000-rpm rotation frequency of the working electrode, and a 600-s pre-concentration time. Voltammetric measurements were obtained using linear scan (LSV), differential pulse (DPV), and square wave (SWV) modes and detection limits were in the range 10(-9)-10(-8) mol L(-1) for these metal species. The proposed method was compared with a traditional analytical technique, flame atomic absorption spectrometry (FAAS), for quantification of these metal species in commercial fuel ethanol samples.

  10. Who Leads China's Leading Universities?

    ERIC Educational Resources Information Center

    Huang, Futao

    2017-01-01

    This study attempts to identify the major characteristics of two different groups of institutional leaders in China's leading universities. The study begins with a review of relevant literature and theory. Then, there is a brief introduction to the selection of party secretaries, deputy secretaries, presidents and vice presidents in leading…

  11. Who Leads China's Leading Universities?

    ERIC Educational Resources Information Center

    Huang, Futao

    2017-01-01

    This study attempts to identify the major characteristics of two different groups of institutional leaders in China's leading universities. The study begins with a review of relevant literature and theory. Then, there is a brief introduction to the selection of party secretaries, deputy secretaries, presidents and vice presidents in leading…

  12. Self-assembly of biaxial discorectangular lead carbonate nanosheets into stacked ribbons studied by SAXS and HAADF-STEM tomographic tilt series.

    PubMed

    Zhang, J; Vad, T; Heidelmann, M; Weirich, T E; Sager, W F C

    2014-12-21

    The self-assembling behaviour of 2.6 nm thin PbCO3 nanoplatelets with discorectangular shape and uniform width and thickness occurring after their formation in nonionic water-in-oil microemulsions has been investigated using synchrotron small angle X-ray scattering (SAXS) and (scanning) transmission electron microscopy ((S)TEM). The presence of attractive depletion forces originating from the ubiquitous microemulsion droplets triggers a new type of superstructure at low particle concentration. Instead of the universally observed formation of face-to-face assembled lamellar mesostructures, the nanosheets self-organise into extended ribbon structures, whereby each on top lying sheet is displaced by a constant shift in the length and width directions leading to a so far unprecedented staggered zigzag-type stack assembly with restricted height. This type of stacking gives rise to a complex interference pattern in the isotropic small angle scattering of the stacked ribbon assemblies (SRAs) in reverse micellar solution. Different to the, for lamellar-structured nanosheets typical, diffraction peaks at multiples of the wave vector corresponding to one particular repeat distance, the scattering peaks measured in this study are asymmetric, displaying a shoulder on their low wave vector side. The asymmetric shape of the observed face-to-face correlation peaks indicates that the SRAs do not extend in one direction only. Their scattering behaviour is analysed by expanding the Kratky-Porod structure factor for stacking plates into three dimensions. High-angle annular dark-field (HAADF)-STEM tilt series have complementary been acquired to retrieve three-dimensional structural information on the SRAs in the dry state and to confirm the model used for the refinement of the SAXS data.

  13. Lead from calcium supplements contributes minimally to blood lead concentrations

    NASA Astrophysics Data System (ADS)

    Gulson, B. L.; Mizon, K. J.; Palmer, J. M.; Korsch, M. J.; Taylor, A. J.

    2003-05-01

    We undertook a study using lead isotopes to determine the contribution of lead to blood from consumption of calcium supplements approximating the recommended daily intakes over a 6 month period. Subjects were subdivided into three groups. One treatment group (n=8) was administered a complex calcium supplement (carbonite/phosphate/citrate) and the other treatment group (n=7), calcium carbonate. The control group (n=6) received no supplementation. The lead isotopic compositions of the supplements were completely different from those of the blood of the subjects. Lead isotopic compositions for the complex supplement showed minimal change during treatment compared with pre-treatment. Lead isotopic compositions in blood for the calcium carbonate supplement showed increases of up to 0.5% in the ^{206}Pb/^{204}Pb ratio, and for all isotope ratios there was a statistically significant difference between bascline and treatment (p <0.005). Blood tead concentrations showed minimal changes.

  14. 1,3-Oxazole-based selective picomolar inhibitors of cytosolic human carbonic anhydrase II alleviate ocular hypertension in rabbits: Potency is supported by X-ray crystallography of two leads.

    PubMed

    Ferraroni, Marta; Lucarini, Laura; Masini, Emanuela; Korsakov, Mikhail; Scozzafava, Andrea; Supuran, Claudiu T; Krasavin, Mikhail

    2017-09-01

    Two lead 1,3-oxazole-based carbonic anhydrase inhibitors (CAIs) earlier identified as selective, picomolar inhibitors of hCA II (a cytosolic target for treatment of glaucoma) have been investigated further. Firstly, they were found to be conveniently synthesized on multigram scale, which enables further development. These compounds were found to be comparable in efficacy to dorzolamide eye drops when applied in the eye drop form as well. Finally, the reasons for unusually high potency of these compounds became understood from their high-resolution X-ray crystallography structures. These data significantly expand our understanding of heterocycle-based primary sulfonamides, many of which have recently emerged from our labs - particularly, from the corneal permeability standpoint. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, the media record workers on the job preparing the orbiter Atlantis for Return to Flight. Both local and national reporters representing print and TV networks were invited to see work in progress on Atlantis, including the reinstallation of the Reinforced Carbon-Carbon panels on the orbiter’s wing leading edge; wiring inspections; and checks of the engines in the Orbital Maneuvering System.

    NASA Image and Video Library

    2003-09-26

    KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, the media record workers on the job preparing the orbiter Atlantis for Return to Flight. Both local and national reporters representing print and TV networks were invited to see work in progress on Atlantis, including the reinstallation of the Reinforced Carbon-Carbon panels on the orbiter’s wing leading edge; wiring inspections; and checks of the engines in the Orbital Maneuvering System.

  16. Combined processing of lead concentrates

    NASA Astrophysics Data System (ADS)

    Kubasov, V. L.; Paretskii, V. M.; Sidorin, G. N.; Travkin, V. F.

    2013-06-01

    A combined scheme of processing of lead concentrates with the production of pure metallic lead and the important components containing in these concentrates is considered. This scheme includes sulfating roasting of the lead concentrates and two-stage leaching of the formed cinder with the formation of a sulfate solution and lead sulfate. When transformed into a carbonate form, lead sulfate is used for the production of pure metallic lead. Silver, indium, copper, cadmium, nickel, cobalt, and other important components are separately extracted from a solution. At the last stage, zinc is extracted by either extraction followed by electrolytic extraction of a metal or the return of the forming solution of sulfuric acid to cinder leaching.

  17. Study of electrochemically active carbon, Ga2O3 and Bi2O3 as negative additives for valve-regulated lead-acid batteries working under high-rate, partial-state-of-charge conditions

    NASA Astrophysics Data System (ADS)

    Zhao, Li; Chen, Baishuang; Wu, Jinzhu; Wang, Dianlong

    2014-02-01

    Electrochemically active carbon (EAC), Gallium (III) oxide (Ga2O3) and Bismuth (III) oxide (Bi2O3) are used as the negative additives of valve-regulated lead-acid (VRLA) batteries to prolong the cycle life of VRLA batteries under high-rate partial-state-of-charge (HRPSoC) conditions, and their effects on the cycle life of VRLA batteries are investigated. It is found that the addition of EAC in negative active material can restrain the sulfation of the negative plates and prolong the cycle performance of VRLA batteries under HRPSoC conditions. It is also observed that the addition of Ga2O3 or Bi2O3 in EAC can effectively increase the overpotential of hydrogen evolution on EAC electrodes, and decrease the evolution rate of hydrogen. An appropriate addition amount of Ga2O3 or Bi2O3 in the negative plates of VRLA batteries can decrease the cut-off charging voltage, increase the cut-off discharging voltage, and prolong the cycle life of VRLA batteries under HRPSoC conditions. The battery added with 0.5% EAC and 0.01% Ga2O3 in negative active material shows a lowest cut-off charging voltage and a highest cut-off discharging voltage under HRPSoC conditions, and its' cycle life reaches about 8100 cycles which is at least three times longer than that without Ga2O3.

  18. The Use of Zinc-Lead Composites to Prevent the Corrosion of Lead

    DTIC Science & Technology

    2010-02-01

    Engineering Research Laboratory Charles A. Weiss, Jr., Ph.D. Philip G. Malone , Ph.D. Geotechnical and Structures Laboratory U.S. Army Corrosion Summit 2010 9...hazard  Lead hydroxide, lead carbonate, and lead sulfate can be distributed into the environment  Lead poisoning is serious and difficult to

  19. KENNEDY SPACE CENTER, FLA. - United Space Alliance employee Anthony Simmons prepares to electroweld a crack found on an insulator inside a Reinforced Carbon Carbon panel. The gray carbon composite RCC panels are attached to the leading edge of the wing of the orbiters to withstand the aerodynamic forces experienced during launch and reentry, which can reach as high as 800 pounds per square foot. The operating range of RCC is from minus 250º F to about 3,000º F, the temperature produced by friction with the atmosphere during reentry.

    NASA Image and Video Library

    2003-09-16

    KENNEDY SPACE CENTER, FLA. - United Space Alliance employee Anthony Simmons prepares to electroweld a crack found on an insulator inside a Reinforced Carbon Carbon panel. The gray carbon composite RCC panels are attached to the leading edge of the wing of the orbiters to withstand the aerodynamic forces experienced during launch and reentry, which can reach as high as 800 pounds per square foot. The operating range of RCC is from minus 250º F to about 3,000º F, the temperature produced by friction with the atmosphere during reentry.

  20. KENNEDY SPACE CENTER, FLA. - United Space Alliance employee Anthony Simmons continues electrowelding on an insulator inside a Reinforced Carbon Carbon panel. The gray carbon composite RCC panels are attached to the leading edge of the wing of the orbiters to withstand the aerodynamic forces experienced during launch and reentry, which can reach as high as 800 pounds per square foot. The operating range of RCC is from minus 250º F to about 3,000º F, the temperature produced by friction with the atmosphere during reentry.

    NASA Image and Video Library

    2003-09-16

    KENNEDY SPACE CENTER, FLA. - United Space Alliance employee Anthony Simmons continues electrowelding on an insulator inside a Reinforced Carbon Carbon panel. The gray carbon composite RCC panels are attached to the leading edge of the wing of the orbiters to withstand the aerodynamic forces experienced during launch and reentry, which can reach as high as 800 pounds per square foot. The operating range of RCC is from minus 250º F to about 3,000º F, the temperature produced by friction with the atmosphere during reentry.

  1. KENNEDY SPACE CENTER, FLA. - United Space Alliance employee Anthony Simmons prepares to electroweld a crack formed in the insulator inside a Reinforced Carbon Carbon panel. The gray carbon composite RCC panels are attached to the leading edge of the wing of the orbiters to withstand the aerodynamic forces experienced during launch and reentry, which can reach as high as 800 pounds per square foot. The operating range of RCC is from minus 250º F to about 3,000º F, the temperature produced by friction with the atmosphere during reentry.

    NASA Image and Video Library

    2003-09-16

    KENNEDY SPACE CENTER, FLA. - United Space Alliance employee Anthony Simmons prepares to electroweld a crack formed in the insulator inside a Reinforced Carbon Carbon panel. The gray carbon composite RCC panels are attached to the leading edge of the wing of the orbiters to withstand the aerodynamic forces experienced during launch and reentry, which can reach as high as 800 pounds per square foot. The operating range of RCC is from minus 250º F to about 3,000º F, the temperature produced by friction with the atmosphere during reentry.

  2. KENNEDY SPACE CENTER, FLA. - United Space Alliance employee Anthony Simmons electrowelds a crack formed in the insulator inside a Reinforced Carbon Carbon panel. The gray carbon composite RCC panels are attached to the leading edge of the wing of the orbiters to withstand the aerodynamic forces experienced during launch and reentry, which can reach as high as 800 pounds per square foot. The operating range of RCC is from minus 250º F to about 3,000º F, the temperature produced by friction with the atmosphere during reentry.

    NASA Image and Video Library

    2003-09-16

    KENNEDY SPACE CENTER, FLA. - United Space Alliance employee Anthony Simmons electrowelds a crack formed in the insulator inside a Reinforced Carbon Carbon panel. The gray carbon composite RCC panels are attached to the leading edge of the wing of the orbiters to withstand the aerodynamic forces experienced during launch and reentry, which can reach as high as 800 pounds per square foot. The operating range of RCC is from minus 250º F to about 3,000º F, the temperature produced by friction with the atmosphere during reentry.

  3. KENNEDY SPACE CENTER, FLA. - United Space Alliance employee Anthony Simmons checks the electroweld he performed on an insulator inside a Reinforced Carbon Carbon panel. The gray carbon composite RCC panels are attached to the leading edge of the wing of the orbiters to withstand the aerodynamic forces experienced during launch and reentry, which can reach as high as 800 pounds per square foot. The operating range of RCC is from minus 250º F to about 3,000º F, the temperature produced by friction with the atmosphere during reentry.

    NASA Image and Video Library

    2003-09-16

    KENNEDY SPACE CENTER, FLA. - United Space Alliance employee Anthony Simmons checks the electroweld he performed on an insulator inside a Reinforced Carbon Carbon panel. The gray carbon composite RCC panels are attached to the leading edge of the wing of the orbiters to withstand the aerodynamic forces experienced during launch and reentry, which can reach as high as 800 pounds per square foot. The operating range of RCC is from minus 250º F to about 3,000º F, the temperature produced by friction with the atmosphere during reentry.

  4. KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, Jim Landy (left), NDE specialist with United Space Alliance (USA), prepares to examine a Reinforced Carbon Carbon panel using flash thermography. Helping out, at right, is Dan Phillips, also with USA. Attached to the leading edge of the wing of the orbiters, the gray carbon composite RCC panels have sufficient strength to withstand the aerodynamic forces experienced during launch and reentry, which can reach as high as 800 pounds per square foot. The operating range of RCC is from minus 250º F to about 3,000º F, the temperature produced by friction with the atmosphere during reentry.

    NASA Image and Video Library

    2003-09-09

    KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, Jim Landy (left), NDE specialist with United Space Alliance (USA), prepares to examine a Reinforced Carbon Carbon panel using flash thermography. Helping out, at right, is Dan Phillips, also with USA. Attached to the leading edge of the wing of the orbiters, the gray carbon composite RCC panels have sufficient strength to withstand the aerodynamic forces experienced during launch and reentry, which can reach as high as 800 pounds per square foot. The operating range of RCC is from minus 250º F to about 3,000º F, the temperature produced by friction with the atmosphere during reentry.

  5. KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, United Space Alliance workers Dan Kenna and Jim Landy prepare to examine a Reinforced Carbon Carbon panel using flash thermography. Attached to the leading edge of the wing of the orbiters, the gray carbon composite RCC panels have sufficient strength to withstand the aerodynamic forces experienced during launch and reentry, which can reach as high as 800 pounds per square foot. The operating range of RCC is from minus 250º F to about 3,000º F, the temperature produced by friction with the atmosphere during reentry.

    NASA Image and Video Library

    2003-09-09

    KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, United Space Alliance workers Dan Kenna and Jim Landy prepare to examine a Reinforced Carbon Carbon panel using flash thermography. Attached to the leading edge of the wing of the orbiters, the gray carbon composite RCC panels have sufficient strength to withstand the aerodynamic forces experienced during launch and reentry, which can reach as high as 800 pounds per square foot. The operating range of RCC is from minus 250º F to about 3,000º F, the temperature produced by friction with the atmosphere during reentry.

  6. KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, United Space Alliance workers Mike Hyatt (left), Saul Ngy (center) and Jerry Belt (right) prepare to install a Reinforced Carbon Carbon (RCC) panel to the leading edge of the wing of the orbiter Atlantis. The gray carbon composite RCC panels have sufficient strength to withstand the aerodynamic forces experienced during launch and reentry, which can reach as high as 800 pounds per square foot. The operating range of RCC is from minus 250º F to about 3,000º F, the temperature produced by friction with the atmosphere during reentry.

    NASA Image and Video Library

    2003-09-08

    KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, United Space Alliance workers Mike Hyatt (left), Saul Ngy (center) and Jerry Belt (right) prepare to install a Reinforced Carbon Carbon (RCC) panel to the leading edge of the wing of the orbiter Atlantis. The gray carbon composite RCC panels have sufficient strength to withstand the aerodynamic forces experienced during launch and reentry, which can reach as high as 800 pounds per square foot. The operating range of RCC is from minus 250º F to about 3,000º F, the temperature produced by friction with the atmosphere during reentry.

  7. KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, United Space Alliance workers (left to right) Jim Landy, Dan Phillips, Paul Ogletree and Dan Kenna check results of flash thermography on the Reinforced Carbon Carbon panel on the table (foreground). Attached to the leading edge of the wing of the orbiters, the gray carbon composite RCC panels have sufficient strength to withstand the aerodynamic forces experienced during launch and reentry, which can reach as high as 800 pounds per square foot. The operating range of RCC is from minus 250º F to about 3,000º F, the temperature produced by friction with the atmosphere during reentry.

    NASA Image and Video Library

    2003-09-09

    KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, United Space Alliance workers (left to right) Jim Landy, Dan Phillips, Paul Ogletree and Dan Kenna check results of flash thermography on the Reinforced Carbon Carbon panel on the table (foreground). Attached to the leading edge of the wing of the orbiters, the gray carbon composite RCC panels have sufficient strength to withstand the aerodynamic forces experienced during launch and reentry, which can reach as high as 800 pounds per square foot. The operating range of RCC is from minus 250º F to about 3,000º F, the temperature produced by friction with the atmosphere during reentry.

  8. KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, United Space Alliance worker Mike Hyatt (right) attaches a Reinforced Carbon Carbon (RCC) panel onto the leading edge of the wing of the orbiter Atlantis. The gray carbon composite RCC panels have sufficient strength to withstand the aerodynamic forces experienced during launch and reentry, which can reach as high as 800 pounds per square foot. The operating range of RCC is from minus 250º F to about 3,000º F, the temperature produced by friction with the atmosphere during reentry.

    NASA Image and Video Library

    2003-09-05

    KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, United Space Alliance worker Mike Hyatt (right) attaches a Reinforced Carbon Carbon (RCC) panel onto the leading edge of the wing of the orbiter Atlantis. The gray carbon composite RCC panels have sufficient strength to withstand the aerodynamic forces experienced during launch and reentry, which can reach as high as 800 pounds per square foot. The operating range of RCC is from minus 250º F to about 3,000º F, the temperature produced by friction with the atmosphere during reentry.

  9. KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, United Space Alliance workers Mike Hyatt (above), Saul Ngy (right) and Jerry Belt (below) install a Reinforced Carbon Carbon (RCC) panel to the leading edge of the wing of the orbiter Atlantis. The gray carbon composite RCC panels have sufficient strength to withstand the aerodynamic forces experienced during launch and reentry, which can reach as high as 800 pounds per square foot. The operating range of RCC is from minus 250º F to about 3,000º F, the temperature produced by friction with the atmosphere during reentry.

    NASA Image and Video Library

    2003-09-08

    KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, United Space Alliance workers Mike Hyatt (above), Saul Ngy (right) and Jerry Belt (below) install a Reinforced Carbon Carbon (RCC) panel to the leading edge of the wing of the orbiter Atlantis. The gray carbon composite RCC panels have sufficient strength to withstand the aerodynamic forces experienced during launch and reentry, which can reach as high as 800 pounds per square foot. The operating range of RCC is from minus 250º F to about 3,000º F, the temperature produced by friction with the atmosphere during reentry.

  10. KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, United Space Alliance workers Mike Hyatt (above) and Saul Ngy (below right) finish installing a Reinforced Carbon Carbon (RCC) panel to the leading edge of the wing of the orbiter Atlantis. The gray carbon composite RCC panels have sufficient strength to withstand the aerodynamic forces experienced during launch and reentry, which can reach as high as 800 pounds per square foot. The operating range of RCC is from minus 250º F to about 3,000º F, the temperature produced by friction with the atmosphere during reentry.

    NASA Image and Video Library

    2003-09-08

    KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, United Space Alliance workers Mike Hyatt (above) and Saul Ngy (below right) finish installing a Reinforced Carbon Carbon (RCC) panel to the leading edge of the wing of the orbiter Atlantis. The gray carbon composite RCC panels have sufficient strength to withstand the aerodynamic forces experienced during launch and reentry, which can reach as high as 800 pounds per square foot. The operating range of RCC is from minus 250º F to about 3,000º F, the temperature produced by friction with the atmosphere during reentry.

  11. KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, United Space Alliance worker Mike Hyatt attaches a Reinforced Carbon Carbon (RCC) panel onto the leading edge of the wing of the orbiter Atlantis. The gray carbon composite RCC panels have sufficient strength to withstand the aerodynamic forces experienced during launch and reentry, which can reach as high as 800 pounds per square foot. The operating range of RCC is from minus 250º F to about 3,000º F, the temperature produced by friction with the atmosphere during reentry.

    NASA Image and Video Library

    2003-09-05

    KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, United Space Alliance worker Mike Hyatt attaches a Reinforced Carbon Carbon (RCC) panel onto the leading edge of the wing of the orbiter Atlantis. The gray carbon composite RCC panels have sufficient strength to withstand the aerodynamic forces experienced during launch and reentry, which can reach as high as 800 pounds per square foot. The operating range of RCC is from minus 250º F to about 3,000º F, the temperature produced by friction with the atmosphere during reentry.

  12. KENNEDY SPACE CENTER, FLA. - Billy Witt, a midbody shop mechanic with United Space Alliance, checks a part used for installation of a Reinforced Carbon Carbon (RCC) panel to the leading edge of the wing of an orbiter. Above him is an RCC panel just installed on Atlantis. The gray carbon composite RCC panels have sufficient strength to withstand the aerodynamic forces experienced during launch and reentry, which can reach as high as 800 pounds per square foot. The operating range of RCC is from minus 250º F to about 3,000º F, the temperature produced by friction with the atmosphere during reentry.

    NASA Image and Video Library

    2003-09-08

    KENNEDY SPACE CENTER, FLA. - Billy Witt, a midbody shop mechanic with United Space Alliance, checks a part used for installation of a Reinforced Carbon Carbon (RCC) panel to the leading edge of the wing of an orbiter. Above him is an RCC panel just installed on Atlantis. The gray carbon composite RCC panels have sufficient strength to withstand the aerodynamic forces experienced during launch and reentry, which can reach as high as 800 pounds per square foot. The operating range of RCC is from minus 250º F to about 3,000º F, the temperature produced by friction with the atmosphere during reentry.

  13. KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, United Space Alliance workers (left to right) Jim Landy, Paul Ogletree, Dan Kenna and Dan Phillips check results of flash thermography on the Reinforced Carbon Carbon panel on the table (foreground). Attached to the leading edge of the wing of the orbiters, the gray carbon composite RCC panels have sufficient strength to withstand the aerodynamic forces experienced during launch and reentry, which can reach as high as 800 pounds per square foot. The operating range of RCC is from minus 250º F to about 3,000º F, the temperature produced by friction with the atmosphere during reentry.

    NASA Image and Video Library

    2003-09-09

    KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, United Space Alliance workers (left to right) Jim Landy, Paul Ogletree, Dan Kenna and Dan Phillips check results of flash thermography on the Reinforced Carbon Carbon panel on the table (foreground). Attached to the leading edge of the wing of the orbiters, the gray carbon composite RCC panels have sufficient strength to withstand the aerodynamic forces experienced during launch and reentry, which can reach as high as 800 pounds per square foot. The operating range of RCC is from minus 250º F to about 3,000º F, the temperature produced by friction with the atmosphere during reentry.

  14. KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, United Space Alliance workers Jim Landy (front), Dan Phillips and Dan Kenna watch a monitor showing results of flash thermography on the Reinforced Carbon Carbon panel on the table (foreground). Attached to the leading edge of the wing of the orbiters, the gray carbon composite RCC panels have sufficient strength to withstand the aerodynamic forces experienced during launch and reentry, which can reach as high as 800 pounds per square foot. The operating range of RCC is from minus 250º F to about 3,000º F, the temperature produced by friction with the atmosphere during reentry.

    NASA Image and Video Library

    2003-09-09

    KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, United Space Alliance workers Jim Landy (front), Dan Phillips and Dan Kenna watch a monitor showing results of flash thermography on the Reinforced Carbon Carbon panel on the table (foreground). Attached to the leading edge of the wing of the orbiters, the gray carbon composite RCC panels have sufficient strength to withstand the aerodynamic forces experienced during launch and reentry, which can reach as high as 800 pounds per square foot. The operating range of RCC is from minus 250º F to about 3,000º F, the temperature produced by friction with the atmosphere during reentry.

  15. KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, United Space Alliance workers Mike Hyatt (left) Jerry Belt (center), and Saul Ngy (right), lift a Reinforced Carbon Carbon (RCC) panel they will attach to the leading edge of the wing of the orbiter Atlantis. The gray carbon composite RCC panels have sufficient strength to withstand the aerodynamic forces experienced during launch and reentry, which can reach as high as 800 pounds per square foot. The operating range of RCC is from minus 250º F to about 3,000º F, the temperature produced by friction with the atmosphere during reentry.

    NASA Image and Video Library

    2003-09-05

    KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, United Space Alliance workers Mike Hyatt (left) Jerry Belt (center), and Saul Ngy (right), lift a Reinforced Carbon Carbon (RCC) panel they will attach to the leading edge of the wing of the orbiter Atlantis. The gray carbon composite RCC panels have sufficient strength to withstand the aerodynamic forces experienced during launch and reentry, which can reach as high as 800 pounds per square foot. The operating range of RCC is from minus 250º F to about 3,000º F, the temperature produced by friction with the atmosphere during reentry.

  16. KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, United Space Alliance workers share the task of examining a Reinforced Carbon Carbon panel using flash thermography. From left are Dan Kenna, Jim Landy, Paul Ogletree and Dan Phillips. Attached to the leading edge of the wing of the orbiters, the gray carbon composite RCC panels have sufficient strength to withstand the aerodynamic forces experienced during launch and reentry, which can reach as high as 800 pounds per square foot. The operating range of RCC is from minus 250º F to about 3,000º F, the temperature produced by friction with the atmosphere during reentry.

    NASA Image and Video Library

    2003-09-09

    KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, United Space Alliance workers share the task of examining a Reinforced Carbon Carbon panel using flash thermography. From left are Dan Kenna, Jim Landy, Paul Ogletree and Dan Phillips. Attached to the leading edge of the wing of the orbiters, the gray carbon composite RCC panels have sufficient strength to withstand the aerodynamic forces experienced during launch and reentry, which can reach as high as 800 pounds per square foot. The operating range of RCC is from minus 250º F to about 3,000º F, the temperature produced by friction with the atmosphere during reentry.

  17. KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, United Space Alliance workers share the task of examining a Reinforced Carbon Carbon panel using flash thermography. From left are Paul Ogletree, Jim Landy (kneeling), Dan Phillips and Dan Kenna. Attached to the leading edge of the wing of the orbiters, the gray carbon composite RCC panels have sufficient strength to withstand the aerodynamic forces experienced during launch and reentry, which can reach as high as 800 pounds per square foot. The operating range of RCC is from minus 250º F to about 3,000º F, the temperature produced by friction with the atmosphere during reentry.

    NASA Image and Video Library

    2003-09-09

    KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, United Space Alliance workers share the task of examining a Reinforced Carbon Carbon panel using flash thermography. From left are Paul Ogletree, Jim Landy (kneeling), Dan Phillips and Dan Kenna. Attached to the leading edge of the wing of the orbiters, the gray carbon composite RCC panels have sufficient strength to withstand the aerodynamic forces experienced during launch and reentry, which can reach as high as 800 pounds per square foot. The operating range of RCC is from minus 250º F to about 3,000º F, the temperature produced by friction with the atmosphere during reentry.

  18. KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, United Space Alliance workers Mike Hyatt (left) Saul Ngy (center) and Jerry Belt (right) lift a Reinforced Carbon Carbon (RCC) panel to attach onto the leading edge of the wing of the orbiter Atlantis. The gray carbon composite RCC panels have sufficient strength to withstand the aerodynamic forces experienced during launch and reentry, which can reach as high as 800 pounds per square foot. The operating range of RCC is from minus 250º F to about 3,000º F, the temperature produced by friction with the atmosphere during reentry.

    NASA Image and Video Library

    2003-09-05

    KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, United Space Alliance workers Mike Hyatt (left) Saul Ngy (center) and Jerry Belt (right) lift a Reinforced Carbon Carbon (RCC) panel to attach onto the leading edge of the wing of the orbiter Atlantis. The gray carbon composite RCC panels have sufficient strength to withstand the aerodynamic forces experienced during launch and reentry, which can reach as high as 800 pounds per square foot. The operating range of RCC is from minus 250º F to about 3,000º F, the temperature produced by friction with the atmosphere during reentry.

  19. KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, Jim Landy, NDE specialist with United Space Alliance (USA), watches a monitor off-screen to examine a Reinforced Carbon Carbon panel using flash thermography. Attached to the leading edge of the wing of the orbiters, the gray carbon composite RCC panels have sufficient strength to withstand the aerodynamic forces experienced during launch and reentry, which can reach as high as 800 pounds per square foot. The operating range of RCC is from minus 250º F to about 3,000º F, the temperature produced by friction with the atmosphere during reentry.

    NASA Image and Video Library

    2003-09-09

    KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, Jim Landy, NDE specialist with United Space Alliance (USA), watches a monitor off-screen to examine a Reinforced Carbon Carbon panel using flash thermography. Attached to the leading edge of the wing of the orbiters, the gray carbon composite RCC panels have sufficient strength to withstand the aerodynamic forces experienced during launch and reentry, which can reach as high as 800 pounds per square foot. The operating range of RCC is from minus 250º F to about 3,000º F, the temperature produced by friction with the atmosphere during reentry.

  20. KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, United Space Alliance worker Mike Hyatt looks over a Reinforced Carbon Carbon (RCC) panel that will be attached to the leading edge of the wing of the orbiter Atlantis. The gray carbon composite RCC panels have sufficient strength to withstand the aerodynamic forces experienced during launch and reentry, which can reach as high as 800 pounds per square foot. The operating range of RCC is from minus 250º F to about 3,000º F, the temperature produced by friction with the atmosphere during reentry.

    NASA Image and Video Library

    2003-09-08

    KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, United Space Alliance worker Mike Hyatt looks over a Reinforced Carbon Carbon (RCC) panel that will be attached to the leading edge of the wing of the orbiter Atlantis. The gray carbon composite RCC panels have sufficient strength to withstand the aerodynamic forces experienced during launch and reentry, which can reach as high as 800 pounds per square foot. The operating range of RCC is from minus 250º F to about 3,000º F, the temperature produced by friction with the atmosphere during reentry.

  1. KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, United Space Alliance worker Mike Hyatt (above) completes installation of a Reinforced Carbon Carbon (RCC) panel onto the leading edge of the wing of the orbiter Atlantis. The gray carbon composite RCC panels have sufficient strength to withstand the aerodynamic forces experienced during launch and reentry, which can reach as high as 800 pounds per square foot. The operating range of RCC is from minus 250º F to about 3,000º F, the temperature produced by friction with the atmosphere during reentry.

    NASA Image and Video Library

    2003-09-05

    KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, United Space Alliance worker Mike Hyatt (above) completes installation of a Reinforced Carbon Carbon (RCC) panel onto the leading edge of the wing of the orbiter Atlantis. The gray carbon composite RCC panels have sufficient strength to withstand the aerodynamic forces experienced during launch and reentry, which can reach as high as 800 pounds per square foot. The operating range of RCC is from minus 250º F to about 3,000º F, the temperature produced by friction with the atmosphere during reentry.

  2. KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, United Space Alliance worker Dan Kenna (right) positions a Reinforced Carbon Carbon panel on the table to perform flash thermography. In the background, Paul Ogletree observes the monitor. Attached to the leading edge of the wing of the orbiters, the gray carbon composite RCC panels have sufficient strength to withstand the aerodynamic forces experienced during launch and reentry, which can reach as high as 800 pounds per square foot. The operating range of RCC is from minus 250º F to about 3,000º F, the temperature produced by friction with the atmosphere during reentry.

    NASA Image and Video Library

    2003-09-09

    KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, United Space Alliance worker Dan Kenna (right) positions a Reinforced Carbon Carbon panel on the table to perform flash thermography. In the background, Paul Ogletree observes the monitor. Attached to the leading edge of the wing of the orbiters, the gray carbon composite RCC panels have sufficient strength to withstand the aerodynamic forces experienced during launch and reentry, which can reach as high as 800 pounds per square foot. The operating range of RCC is from minus 250º F to about 3,000º F, the temperature produced by friction with the atmosphere during reentry.

  3. KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, United Space Alliance workers, from center, left to right, Saul Ngy, Jerry Belt and Mike Hyatt, prepare to attach a Reinforced Carbon Carbon (RCC) panel (on the table) to the leading edge of the wing of the orbiter Atlantis. The gray carbon composite RCC panels have sufficient strength to withstand the aerodynamic forces experienced during launch and reentry, which can reach as high as 800 pounds per square foot. The operating range of RCC is from minus 250º F to about 3,000º F, the temperature produced by friction with the atmosphere during reentry.

    NASA Image and Video Library

    2003-09-05

    KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, United Space Alliance workers, from center, left to right, Saul Ngy, Jerry Belt and Mike Hyatt, prepare to attach a Reinforced Carbon Carbon (RCC) panel (on the table) to the leading edge of the wing of the orbiter Atlantis. The gray carbon composite RCC panels have sufficient strength to withstand the aerodynamic forces experienced during launch and reentry, which can reach as high as 800 pounds per square foot. The operating range of RCC is from minus 250º F to about 3,000º F, the temperature produced by friction with the atmosphere during reentry.

  4. KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, United Space Alliance worker Mike Hyatt (above) finishes installing a Reinforced Carbon Carbon (RCC) panel to the leading edge of the wing of the orbiter Atlantis. The gray carbon composite RCC panels have sufficient strength to withstand the aerodynamic forces experienced during launch and reentry, which can reach as high as 800 pounds per square foot. The operating range of RCC is from minus 250º F to about 3,000º F, the temperature produced by friction with the atmosphere during reentry.

    NASA Image and Video Library

    2003-09-08

    KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, United Space Alliance worker Mike Hyatt (above) finishes installing a Reinforced Carbon Carbon (RCC) panel to the leading edge of the wing of the orbiter Atlantis. The gray carbon composite RCC panels have sufficient strength to withstand the aerodynamic forces experienced during launch and reentry, which can reach as high as 800 pounds per square foot. The operating range of RCC is from minus 250º F to about 3,000º F, the temperature produced by friction with the atmosphere during reentry.

  5. KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, United Space Alliance worker Mike Hyatt (above) attaches a Reinforced Carbon Carbon (RCC) panel onto the leading edge of the wing of the orbiter Atlantis. The gray carbon composite RCC panels have sufficient strength to withstand the aerodynamic forces experienced during launch and reentry, which can reach as high as 800 pounds per square foot. The operating range of RCC is from minus 250º F to about 3,000º F, the temperature produced by friction with the atmosphere during reentry.

    NASA Image and Video Library

    2003-09-05

    KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, United Space Alliance worker Mike Hyatt (above) attaches a Reinforced Carbon Carbon (RCC) panel onto the leading edge of the wing of the orbiter Atlantis. The gray carbon composite RCC panels have sufficient strength to withstand the aerodynamic forces experienced during launch and reentry, which can reach as high as 800 pounds per square foot. The operating range of RCC is from minus 250º F to about 3,000º F, the temperature produced by friction with the atmosphere during reentry.

  6. Carbon-carbon composites

    NASA Technical Reports Server (NTRS)

    Maahs, Howard G.

    1992-01-01

    The current applications of C-C composites extend to aircraft brakes, rocket nozzles, missile nosetips, and leading edges of the Space Shuttle. More advanced, secondary and even primary structure applications in cyclic, high-temperature oxidizing environments depend on effective oxidation protection for repeated missions. Accounts are presently given of state-of-the-art methods in substrate fabrication, carbon deposition, and SiC and Si3N4 protective coatings. Attention is given to current levels of high temperature oxidation protection for various mission and vehicle types, as well as to performance projections for C-C composites used by a representative National Aerospace Plane airframe structure. Future technology requirements in C-C composites are projected.

  7. THE EFFECT OF FLUORIDE ON LEAD SOLUBILITY

    EPA Science Inventory

    Difficulties in predicting and controlling lead corrosion are encountered by hundreds of water systems across the country. Inorganic carbonate, sulfate, silicate, orthophosphate, pH, total organic carbon, temperature and the type/amount of chlorine residual are all known factors ...

  8. THE EFFECT OF FLUORIDE ON LEAD SOLUBILITY

    EPA Science Inventory

    Difficulties in predicting and controlling lead corrosion are encountered by hundreds of water systems across the country. Inorganic carbonate, sulfate, silicate, orthophosphate, pH, total organic carbon, temperature and the type/amount of chlorine residual are all known factors ...

  9. KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, astronaut Michael E. Lopez-Alegria looks at the Reinforced Carbon Carbon panels used on the leading edge of the wing of the orbiters. He and engineers from around the Agency are on a fact-finding tour for improving the RCC panels used on the wing leading edge. The gray carbon composite RCC panels have sufficient strength to withstand the aerodynamic forces experienced during launch and reentry, which can reach as high as 800 pounds per square foot. The operating range of RCC is from minus 250º F to about 3,000º F, the temperature produced by friction with the atmosphere during reentry.

    NASA Image and Video Library

    2003-12-08

    KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, astronaut Michael E. Lopez-Alegria looks at the Reinforced Carbon Carbon panels used on the leading edge of the wing of the orbiters. He and engineers from around the Agency are on a fact-finding tour for improving the RCC panels used on the wing leading edge. The gray carbon composite RCC panels have sufficient strength to withstand the aerodynamic forces experienced during launch and reentry, which can reach as high as 800 pounds per square foot. The operating range of RCC is from minus 250º F to about 3,000º F, the temperature produced by friction with the atmosphere during reentry.

  10. KENNEDY SPACE CENTER, FLA. - - In the Orbiter Processing Facility astronaut Danny Olivas listens to Greg Grantham (left) talking about the Reinforced Carbon Carbon panels used on the leading edge of the wing of the orbiters. Behind Olivas are engineers from around the Agency who are working on improving the RCC panels used on the wing leading edge. The gray carbon composite RCC panels have sufficient strength to withstand the aerodynamic forces experienced during launch and reentry, which can reach as high as 800 pounds per square foot. The operating range of RCC is from minus 250º F to about 3,000º F, the temperature produced by friction with the atmosphere during reentry.

    NASA Image and Video Library

    2003-12-08

    KENNEDY SPACE CENTER, FLA. - - In the Orbiter Processing Facility astronaut Danny Olivas listens to Greg Grantham (left) talking about the Reinforced Carbon Carbon panels used on the leading edge of the wing of the orbiters. Behind Olivas are engineers from around the Agency who are working on improving the RCC panels used on the wing leading edge. The gray carbon composite RCC panels have sufficient strength to withstand the aerodynamic forces experienced during launch and reentry, which can reach as high as 800 pounds per square foot. The operating range of RCC is from minus 250º F to about 3,000º F, the temperature produced by friction with the atmosphere during reentry.

  11. Lead - nutritional considerations

    MedlinePlus

    Lead poisoning - nutritional considerations; Toxic metal - nutritional considerations ... utensils . Old paint poses the greatest danger for lead poisoning , especially in young children. Tap water from lead ...

  12. Lead aVR--the neglected lead.

    PubMed

    Chenniappan, M; Sankar, R Uday; Saravanan, K; Karthikeyan

    2013-09-01

    The aVR is often neglected lead. It is an unipolar lead facing the right superior surface. As all the depolarisations are going away from lead aVR, all waves are negative in aVR (P, QRS, T) in normal sinus rhythm. In dextrocardia, (True and technical) the p is upright in aVR. The lead aVR is a very important lead in localisation of Coronary Artery Disease. In the presence of anterior ST elevation, ST elevation in lead aVR and V1 denotes proximal LAD obstruction where ST elevation is more in lead V1, than in aVR. In the presence of anterior ST depression, ST elevation in lead aVR indicates Left Main Coronary Artery (LMCA) Disease where ST elevation is more in aVR than in V1. In wide QRS tachycardia, tall R wave in aVR indicates Ventricular Tachycardia rather than SVT with aberrancy. In the presence of QS complexes in inferior leads, the lead aVR helps to differentiate between inferior wall MI (IWMI) and left anterior fascicular block (LAFB). Initial R in aVR is suggestive of IWMI and terminal R is suggestive of LAFB. In pericarditis, lead aVR is most often the only lead which shows reciprocal ST depression where as in Acute Infarction, usually a group of leads shows reciprocal depression. In the presence of persistent ST elevation in anterior chest leads, the R in aVR is suggestive of left ventricular aneurysm (Goldburger's sign). In acute pulmonary embolism, ST elevation in lead aVR is a bad prognostic sign. In Tricyclic antidepressant toxicity, R in aVR more than 3 mm is an adverse prognostic sign. So in variety of conditions, the aVR is proved to be a valuable lead not only in diagnosis but also in predicting the prognosis.

  13. Lead levels - blood

    MedlinePlus

    Blood lead levels ... is used to screen people at risk for lead poisoning. This may include industrial workers and children ... also used to measure how well treatment for lead poisoning is working. Lead is common in the ...

  14. Lead (Pb) Air Pollution

    MedlinePlus

    ... States Environmental Protection Agency Search Search Lead (Pb) Air Pollution Share Facebook Twitter Google+ Pinterest Contact Us As ... and protect aquatic and terrestrial ecosystems. Lead (Pb) Air Pollution Lead Air Pollution Basics How does lead get ...

  15. Learn about Lead

    MedlinePlus

    ... the Environment . Top of page What are the Health Effects of Lead? Lead can affect almost every organ ... both men and women) Read more on the health effects of lead EPA’s Integrated Science Assessment for Lead ...

  16. Lead in petrol. The isotopic lead experiment

    SciTech Connect

    Facchetti, S. )

    1989-10-01

    Many studies were dedicated to the evaluation of the impact of automotive lead on the environment and to the assessment of its absorption in the human population. They can be subdivided into two groups, those based on changes of air and blood lead concentrations and those based on changes of air and blood lead isotopic compositions. According to various authors, 50-66% of the lead added to petrol is mobilized in the atmosphere, while most of the remainder adheres to the walls of the exhaust system from which it is expelled by mechanical and thermal shocks in the forms of easily sedimented particles. The fraction directly emitted by engine exhaust fumes is found in the form of fine particles, which can be transferred a long way from the emitting sources. However important the contribution of petrol lead to the total airborne lead may be, our knowledge does not permit a straightforward calculation of the percentage of petrol lead in total blood lead, which of course can also originate from other sources (e.g., industrial, natural). To evaluate this percentage in 1973, the idea of the Isotopic Lead Experiment (ILE project) was conceived to label, on a regional scale, petrol with a nonradioactive lead of an isotopic composition sufficiently different from that of background lead and sufficiently stable in time. This Account summarizes the main results obtained by the ILE project.

  17. Bone lead, hypertension, and lead nephropathy

    SciTech Connect

    Wedeen, R.P.

    1988-06-01

    There is considerable clinical evidence that excessive lead absorption causes renal failure with hypertension and predisposes individuals to hypertension even in the absence of detectable renal failure. Recent analyses of transiliac bone biopsies indicate that unsuspected elevated bone leads may reflect the cause (or contributing cause) of end-stage renal disease in 5% of the European dialysis population. In these patients, bone lead levels were four times higher than in unexposed cadavers (6 micrograms/g wet weight) and approximated levels found in lead workers (30 micrograms/g). At present, the most reliable index of the body lead burden is the CaNa2 EDTA lead mobilization test. In vivo tibial X-ray-induced X-ray fluorescence (XRF) is a more practical noninvasive technique for assessing bone lead, which should find widespread application as a diagnostic tool and for epidemiologic studies.

  18. Carbon Flux Explorers

    SciTech Connect

    Bishop, Jim

    2016-09-09

    Jim Bishop, senior scientist at Berkeley Lab and professor at UC Berkeley, is leading a project to deploy robotic floats that provide data on how microorganisms sequester carbon in the ocean. He recently led a research team on a 10-day voyage, funded by the National Science Foundation, to put the Carbon Flux Explorers to the test.

  19. Carbon Flux Explorers

    ScienceCinema

    Bishop, Jim

    2016-10-12

    Jim Bishop, senior scientist at Berkeley Lab and professor at UC Berkeley, is leading a project to deploy robotic floats that provide data on how microorganisms sequester carbon in the ocean. He recently led a research team on a 10-day voyage, funded by the National Science Foundation, to put the Carbon Flux Explorers to the test.

  20. Lead Aprons Are a Lead Exposure Hazard.

    PubMed

    Burns, Kevin M; Shoag, Jamie M; Kahlon, Sukhraj S; Parsons, Patrick J; Bijur, Polly E; Taragin, Benjamin H; Markowitz, Morri

    2017-05-01

    To determine whether lead-containing shields have lead dust on the external surface. Institutional review board approval was obtained for this descriptive study of a convenience sample of 172 shields. Each shield was tested for external lead dust via a qualitative rapid on-site test and a laboratory-based quantitative dust wipe analysis, flame atomic absorption spectrometry (FAAS). The χ(2) test was used to test the association with age, type of shield, lead sheet thickness, storage method, and visual and radiographic appearance. Sixty-three percent (95% confidence interval [CI]: 56%-70%) of the shields had detectable surface lead by FAAS and 50% (95% CI: 43%-57%) by the qualitative method. Lead dust by FAAS ranged from undetectable to 998 μg/ft(2). The quantitative detection of lead was significantly associated with the following: (1) visual appearance of the shield (1 = best, 3 = worst): 88% of shields that scored 3 had detectable dust lead; (2) type of shield: a greater proportion of the pediatric patient, full-body, and thyroid shields were positive than vests and skirts; (3) use of a hanger for storage: 27% of shields on a hanger were positive versus 67% not on hangers. Radiographic determination of shield intactness, thickness of interior lead sheets, and age of shield were unrelated to presence of surface dust lead. Sixty-three percent of shields had detectable surface lead that was associated with visual appearance, type of shield, and storage method. Lead-containing shields are a newly identified, potentially widespread source of lead exposure in the health industry. Copyright © 2016 American College of Radiology. Published by Elsevier Inc. All rights reserved.

  1. The Carbon Cycle

    NASA Astrophysics Data System (ADS)

    Wigley, T. M. L.; Schimel, D. S.

    2005-08-01

    Reducing carbon dioxide (CO2) emissions is imperative to stabilizing our future climate. Our ability to reduce these emissions combined with an understanding of how much fossil-fuel-derived CO2 the oceans and plants can absorb is central to mitigating climate change. In The Carbon Cycle, leading scientists examine how atmospheric carbon dioxide concentrations have changed in the past and how this may affect the concentrations in the future. They look at the carbon budget and the "missing sink" for carbon dioxide. They offer approaches to modeling the carbon cycle, providing mathematical tools for predicting future levels of carbon dioxide. This comprehensive text incorporates findings from the recent IPCC reports. New insights, and a convergence of ideas and views across several disciplines make this book an important contribution to the global change literature.

  2. Reduction of Ribulose-1,5-Bisphosphate Carboxylase/Oxygenase by Antisense RNA in the C4 Plant Flaveria bidentis Leads to Reduced Assimilation Rates and Increased Carbon Isotope Discrimination.

    PubMed Central

    Von Caemmerer, S.; Millgate, A.; Farquhar, G. D.; Furbank, R. T.

    1997-01-01

    Transgenic Flaveria bidentis (a C4 species) plants with an antisense gene directed against the mRNA of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) were used to examine the relationship between the CO2 assimilation rate, Rubisco content, and carbon isotope discrimination. Reduction in the amount of Rubisco in the transgenic plants resulted in reduced CO2 assimilation rates and increased carbon isotope discrimination of leaf dry matter. The H2O exchange was similar in transgenic and wild-type plants, resulting in higher ratios of intercellular to ambient CO2 partial pressures. Carbon isotope discrimination was measured concurrently with CO2 and H2O exchange on leaves of the control plants and T1 progeny with a 40% reduction in Rubisco. From the theory of carbon isotope discrimination in the C4 species, we conclude that the reduction in the Rubisco content in the transgenic plants has led to an increase in bundle-sheath CO2 concentration and CO2 leakage from the bundle sheath; however, some down-regulation of the C4 cycle also occurred. PMID:12223620

  3. Novel lead-graphene and lead-graphite metallic composite materials for possible applications as positive electrode grid in lead-acid battery

    NASA Astrophysics Data System (ADS)

    Yolshina, L. A.; Yolshina, V. A.; Yolshin, A. N.; Plaksin, S. V.

    2015-03-01

    Novel lead-graphene and lead-graphite metallic composites which melt at temperature of the melting point of lead were investigated as possible positive current collectors for lead acid batteries in sulfuric acid solution. Scanning electron microscopy, Raman spectroscopy, difference scanning calorimetry, cyclic voltammetry and prolonged corrosion tests were employed to characterize the effect of the newly proposed lead-carbon metallic composites on the structure and electrochemical properties of positive grid material. Both lead-graphene and lead-graphite metallic composite materials show the similar electrochemical characteristics to metallic lead in the voltage range where the positive electrodes of lead acid batteries operate. It has been shown that carbon both as graphene and graphite does not participate in the electrochemical process but improve corrosion and electrochemical characteristics of both metallic composite materials. No products of interaction of lead with sulfuric acid were formed on the surface of graphene and graphite so as it was not found additional peaks of carbon discharge on voltammograms which could be attributed to the carbon. Graphene inclusions in lead prevent formation of leady oxide nanocrystals which deteriorate discharge characteristics of positive electrode of LAB. Both lead-graphene alloy and lead-graphite metallic composite proved excellent electrochemical and corrosion behavior and can be used as positive grids in lead acid batteries of new generation.

  4. Lead and the Romans

    ERIC Educational Resources Information Center

    Reddy, Aravind; Braun, Charles L.

    2010-01-01

    Lead poisoning has been a problem since early history and continues into modern times. An appealing characteristic of lead is that many lead salts are sweet. In the absence of cane and beet sugars, early Romans used "sugar of lead" (lead acetate) to sweeten desserts, fruits, and sour wine. People most at risk would have been those who…

  5. Lead and the Romans

    ERIC Educational Resources Information Center

    Reddy, Aravind; Braun, Charles L.

    2010-01-01

    Lead poisoning has been a problem since early history and continues into modern times. An appealing characteristic of lead is that many lead salts are sweet. In the absence of cane and beet sugars, early Romans used "sugar of lead" (lead acetate) to sweeten desserts, fruits, and sour wine. People most at risk would have been those who…

  6. The synthesis of organic carbonates from carbon dioxide.

    PubMed

    Sakakura, Toshiyasu; Kohno, Kazufumi

    2009-03-21

    Carbon dioxide (CO(2)) is an easily available, renewable carbon resource, which has the advantages of being non-toxic, abundant and economical. CO(2) is also attractive as an environmentally friendly chemical reagent, and is especially useful as a phosgene substitute. CO(2) is an "anhydrous carbonic acid" that rapidly reacts with basic compounds. Nucleophilic attack at CO(2) conveniently produces carboxyl and carbamoyl groups. Further reactions of these species with electrophiles lead to the formation of organic carbonates and carbamates. The present article deals with the synthetic technologies leading to organic carbonates using CO(2) as a raw material.

  7. Potential impacts of carbon taxes on carbon flux in western Oregon private forests

    Treesearch

    Eun Ho Im; Darius M. Adams; Gregory S. Latta

    2007-01-01

    This study considers a carbon tax system as a policy tool for encouraging carbon sequestration through modification of management in existing forests and examines its welfare impacts and costs of the carbon sequestered. The simulated carbon tax leads to reduced harvest and increased carbon stock in the standing trees and understory biomass. Changes in the level of...

  8. Perspectives on lead toxicity.

    PubMed

    Lockitch, G

    1993-10-01

    Lead toxicity causes hematological, gastrointestinal, and neurological dysfunction in adults and children. Symptoms are usually noted with blood lead greater than 1.93 mumol/L. Severe or prolonged exposure may also cause chronic nephropathy, hypertension, and reproductive impairment. Lead inhibits enzymes; alters cellular calcium metabolism; stimulates synthesis of binding proteins in kidney, brain, and bone; and slows nerve conduction. Less severe exposure to lead, designated by blood lead levels of 0.48-0.96 mumol/L, has been implicated in poor pregnancy outcome, impaired neurobehavioral development, reduced stature in young children, and higher blood pressure in adults. Biochemical and systemic effects of high and low level lead toxicity are described. Dust, water, and paint chips are still major sources of lead but lead from folk remedies, cosmetics, food supplements, food preparation utensils, and improperly prepared infant formula has caused epidemic and sporadic severe lead toxicity. Screening for pediatric low level lead exposure requires measurement of blood lead.

  9. Lead Surveillance Program

    NASA Technical Reports Server (NTRS)

    1993-01-01

    Background on lead exposure is presented including forms of lead, sources, hematologic effects, neurologic effects, endocrine effects, renal effects, and reproductive and developmental effects. The purpose of the Lead Surveillance Program at LeRC is outlined, and the specifics of the Medical Surveillance Program for Lead Exposure at LeRC are discussed.

  10. The lack of alternative oxidase at low temperature leads to a disruption of the balance in carbon and nitrogen metabolism, and to an up-regulation of antioxidant defence systems in Arabidopsis thaliana leaves.

    PubMed

    Watanabe, Chihiro K; Hachiya, Takushi; Terashima, Ichiro; Noguchi, Ko

    2008-08-01

    Alternative oxidase (AOX) catalyses the ATP-uncoupling cyanide (CN)-resistant pathway. In this study, our aim was to clarify the physiological role of AOX at low temperature. We examined the effect of low-temperature treatment on CN-resistant respiration (CN-resistant R) and on the transcription of respiratory components in wild-type (WT) and aox1a knock-out transgenic (aox1a) Arabidopsis thaliana plants. In WT leaves, the expression of AOX1a mRNA was strongly induced by the low-temperature treatment, and thus CN-resistant R increased during low-temperature treatment. In aox1a, the CN-sensitive respiration, and the expression of NDB2 and UCP1 were increased compared with WT. We compared several physiological parameters between WT and aox1a. Low-temperature treatment did not result in a visible phenotype to distinguish aox1a from WT. In aox1a, several antioxidant defence genes were induced, and the malondialdehyde content was lower than in WT. Starch content and a ratio of carbon to nitrogen were higher in aox1a than in WT. Our results indicate that a lack of AOX was linked to a difference in the carbon and nitrogen balance, and an up-regulation of the transcription of antioxidant defence system at low temperature. It is likely that AOX is a necessary component in antioxidant defence mechanisms and for the control of a balanced metabolism.

  11. Transboundary atmospheric lead pollution.

    PubMed

    Erel, Yigal; Axelrod, Tamar; Veron, Alain; Mahrer, Yitzak; Katsafados, Petros; Dayan, Uri

    2002-08-01

    A high-temporal resolution collection technique was applied to refine aerosol sampling in Jerusalem, Israel. Using stable lead isotopes, lead concentrations, synoptic data, and atmospheric modeling, we demonstrate that lead detected in the atmosphere of Jerusalem is not only anthropogenic lead of local origin but also lead emitted in other countries. Fifty-seven percent of the collected samples contained a nontrivial fraction of foreign atmospheric lead and had 206Pb/207Pb values which deviated from the local petrol-lead value (206Pb/207Pb = 1.113) by more than two standard deviations (0.016). Foreign 206Pb/207Pb values were recorded in Jerusalem on several occasions. The synoptic conditions on these dates and reported values of the isotopic composition of lead emitted in various countries around Israel suggest that the foreign lead was transported to Jerusalem from Egypt, Turkey, and East Europe. The average concentration of foreign atmospheric lead in Jerusalem was 23 +/- 17 ng/m3, similar to the average concentration of local atmospheric lead, 21 +/- 18 ng/ m3. Hence, the load of foreign atmospheric lead is similar to the load of local atmospheric lead in Jerusalem.

  12. Lead Content of Foodstuffs

    PubMed Central

    Mitchell, Douglas G.; Aldous, Kenneth M.

    1974-01-01

    The lead content of a number of foodstuffs, particularly baby fruit juices and milk, is reported. Samples were analyzed in quadruplicate by using an automated Delves cup atomic absorption procedure. A large proportion of the products examined contained significant amounts of lead. Of 256 metal can examined, the contents of 62% contained a lead level of 100 μg/l. or more, 37% contained 200 μg/l. or more and 12% contained 400 μg/l. lead or more. Of products in glass and aluminum containers, only 1% had lead levels in excess of 200 μg/l. Lead levels of contents also correlate with the seam length/volume ratio of the leaded seam can. A survey of bulk milk showed a mean lead level of 40 μg/l. for 270 samples; for canned evaporated milk the mean level was 202 μg/l. These data indicate a potential health hazard. PMID:4406645

  13. Lead Poisoning (For Parents)

    MedlinePlus

    ... metal used in everything from construction materials to batteries, can cause serious health problems, particularly in young ... introduce lead dust into the home. water that flows through old lead pipes or faucets, if the ...

  14. Aquatic Life Criteria - Lead

    EPA Pesticide Factsheets

    References and documents pertaining to Acute and Chronic Ambient Aquatic Life Water Quality Criteria for Lead. These documents include the safe levels of Lead in water that should protect the majority of species.

  15. Lead and tap water

    MedlinePlus

    Water contaminated with lead ... The Environmental Protection Agency (EPA) monitors drinking water in the United States. It requires water suppliers to produce annual water quality reports. These reports include information about lead amounts, and they ...

  16. VOLUMETRIC LEAD ASSAY

    SciTech Connect

    M.A. Ebadian, Ph.D.; S.K. Dua; David Roelant; Sachin Kumar

    2001-01-01

    This report describes a system for handling and radioassay of lead, consisting of a robot, a conveyor, and a gamma spectrometer. The report also presents a cost-benefit analysis of options: radioassay and recycling lead vs. disposal as waste.

  17. Developmental Neurotoxicity of Lead.

    PubMed

    Caito, Samuel; Aschner, Michael

    2017-01-01

    Lead exposure is a major concern for the developing nervous system. Environmental exposures to lead, predominantly from contaminated water or lead paint chips, account for the majority of exposures to children. In utero and early life exposures to lead have been associated with lower IQ, antisocial and delinquent behaviors, and attention-deficit hyperactivity disorder. In this review, we will discuss sources of developmental lead exposure and mechanisms of lead neurotoxicity. We will highlight both human epidemiological studies showing associations between lead exposure and behavioral abnormalities as well as experimental data from animal studies. Finally, we will discuss the effects of lead on neurological endpoint past childhood, namely, development of Alzheimer's disease in old age.

  18. PHOTOEMISSION PROPERTIES OF LEAD.

    SciTech Connect

    SMEDLEY,J.; RAO,T.; WARREN,J.; SEKUTOWICZ,J.; LEFFERTS,R.; LIPSKI,A.

    2004-07-05

    In this paper we present a study of the photoemission properties of lead at several UV wavelengths, including a study of the damage threshold of electroplated lead under laser cleaning. A quantum efficiency in excess of 0.1% has been achieved for a laser cleaned, electroplated lead sample with a laser wavelength of 193 nm. Niobium cathodes have been measured for comparison, and lead is found to be a superior photoemitter for all measured wavelengths.

  19. Transplacental transport of lead

    SciTech Connect

    Goyer, R.A. )

    1990-11-01

    Neurotoxicity is the major health effect from exposure to lead for infants and young children, and there is current concern regarding possible toxic effects of lead on the child while in utero. there is no placental-fetal barrier to lead transport. Maternal and fetal blood lead levels are nearly identical, so lead passes through the placenta unencumbered. Lead has been measured in the fetal brain as early as the end of the first trimester (13 weeks). There is a similar rate of increase in brain size and lead content throughout pregnancy in the fetus of mothers in the general population, so concentration of lead probably does not differ greatly during gestation unless exposure of the mother changes. Cell-specific sensitivity to the toxic effects of lead, however, may be greater the younger the fetus. Lead toxicity to the nervous system is characterized by edema or swelling of the brain due to altered permeability of capillary endothelial cells. Experimental studies suggest that immature endothelial cells forming the capillaries of the developing brain are less resistant to the effects of lead, permitting fluid and cations including lead to reach newly formed components of the brain, particularly astrocytes and neurons. Also, the ability of astrocytes and neurons to sequester lead in the form of lead protein complexes occurs only in the later stages of fetal development, permitting lead in maturing brain cells to interact with vital subcellular organelles, particularly mitochondria, which are the major cellular energy source. Intracellular lead also affects binding sites for calcium which, in turn, may affect numerous cell functions including neurotransmitter release.

  20. [Lead content in alginates].

    PubMed

    Castagnola, L; Wirz, J

    1977-03-01

    Alginates containing a high level of lead may lead to health damages in dentists and their personnel. Walter and Söremark have pointed out these hazards. The author's investigations with the Perkin-Elmer absorption-photospectrometer shall show how high the lead content of the 25 brands of alginate sold in this country is. Ca 37, Protex and Algihard S contain sizeable amounts of lead. Recommendations are given towards the protection of dentist and assistant.

  1. Lead poisoning: An overview

    NASA Technical Reports Server (NTRS)

    Gendel, Neil

    1993-01-01

    A problem that should be of great concern to all of us is the lead poisoning of children. First, I would like to present a short overview concerning the reasons everyone should care about lead poisoning, then discuss the history of lead poisoning, what is happening today across the country, and the future.

  2. Lead Poisoning in Schools.

    ERIC Educational Resources Information Center

    Guyaux, Susan

    1990-01-01

    Overexposure to lead can permanently impair a child's mental and physical development. This article discusses sources of lead paint, survey and testing methods, management and abatement plans, drinking water contamination, and associated federal standards. Although lead is present in soil and in art, theater, and vocational programs, no federal…

  3. Lead Poisoning in Childhood.

    ERIC Educational Resources Information Center

    Pueschel, Siegfried M., Ed.; Linakis, James G., Ed.; Anderson, Angela C., Ed.

    The magnitude of childhood lead poisoning has been inexplicably neglected by modern medicine and by legislators. However, since the 1970s, increased attention has been focused on lead poisoning, and advances have been made in several areas, including understanding of the neurodevelopmental and behavioral ramifications of lead poisoning, and…

  4. Lead Poisoning in Children.

    ERIC Educational Resources Information Center

    Drummond, A. H., Jr.

    1981-01-01

    Early symptoms of lead poisoning in children are often overlooked. Lead poisoning has its greatest effects on the brain and nervous system. The obvious long-term solution to the lead poisoning problem is removal of harmful forms of the metal from the environment. (JN)

  5. Lead Poisoning in Children.

    ERIC Educational Resources Information Center

    Boeckx, Roger L.

    1986-01-01

    Urban children are exposed to lead through the air they breathe, the water they drink, and the food and nonfood substances they ingest. The history, diagnosis, and treatment of lead poisoning in these children are discussed. Includes information on the toxicology of lead and the various risk classes. (JN)

  6. Lead Poisoning in Schools.

    ERIC Educational Resources Information Center

    Guyaux, Susan

    1990-01-01

    Overexposure to lead can permanently impair a child's mental and physical development. This article discusses sources of lead paint, survey and testing methods, management and abatement plans, drinking water contamination, and associated federal standards. Although lead is present in soil and in art, theater, and vocational programs, no federal…

  7. Lead and children

    PubMed Central

    Abelsohn, Alan R.; Sanborn, Margaret

    2010-01-01

    Abstract OBJECTIVE To provide family physicians with a practical, evidence-based approach to screening for and preventing children’s exposure to lead. SOURCES OF INFORMATION MEDLINE was searched using terms relevant to lead exposure and poisoning. We reviewed English-language articles published in 2003 to 2008. Most cited studies provide level 2 or 3 evidence. MAIN MESSAGE Lead is a developmental neurotoxin. Children are most commonly exposed and they are most vulnerable. Lead exposure has been associated with many cognitive and motor deficits, as well as distractibility and other characteristics of attention deficit hyperactivity disorder. Although children’s blood lead levels have declined considerably over the past 3 decades with removal of lead from gasoline and paint, children can still be exposed to lead from lead paint in older homes, toys, and other sources. Because post-exposure treatment cannot reverse the cognitive effects of lead exposure, preventing lead exposure is essential. CONCLUSION Family physicians have an important role in screening for children at high risk of lead exposure, and in educating families to prevent the exposure of children to lead. PMID:20547517

  8. Lead Poisoning in Childhood.

    ERIC Educational Resources Information Center

    Pueschel, Siegfried M., Ed.; Linakis, James G., Ed.; Anderson, Angela C., Ed.

    The magnitude of childhood lead poisoning has been inexplicably neglected by modern medicine and by legislators. However, since the 1970s, increased attention has been focused on lead poisoning, and advances have been made in several areas, including understanding of the neurodevelopmental and behavioral ramifications of lead poisoning, and…

  9. Black Carbon Diesel Initiative in the Russian Arctic

    EPA Pesticide Factsheets

    Mobile and stationary diesel engines are among the largest sources of black carbon emissions in the Arctic. To address this challenge, EPA is leading the Black Carbon Diesel Initiative under the Arctic Black Carbon Initiative (ABCI).

  10. Washing of various lead compounds from a contaminated soil column

    SciTech Connect

    Davis, A.P.; Hotha, B.V.

    1998-11-01

    Soil samples artificially contaminated with 10 different lead compounds to produce 5,000 mg/kg Pb were washed with acid and ethylenediaminetetraacetic acid (EDTA) solutions. For variable pH, the highest washing efficiencies were achieved at pH 2, the lowest value examined. Washing with EDTA enhanced the removal of lead, the removal increasing with an increase in the EDTA:lead molar ratio. High removals (70--106%) of adsorbed lead (as lead nitrate), lead carbonate, basic lead carbonate, lead sulfate, and lead oxide were achieved with both types of washing. Although not washed effectively with acid, significant lead dioxide removal occurred with EDTA wash. The removals of lead sulfide, lead paint, lead dimethyldithiocarbamate, and elemental lead were low (near 0--16%) under all washing conditions. The removal efficiency of the lead is affected by the compound solubility, lead solid dissolution kinetics, and lead sorption into the soil. Results clearly indicate the importance of the form of lead contamination in determining the success of a soil washing operation. Comparison of these results with other suggests that soil washing success and soil lead bioaccessibility are related phenomena.

  11. Law: toxic lead aftermath

    SciTech Connect

    Goldstein, E.A.

    1983-03-01

    The paper describes the events which began with an EPA proposal to weaken the lead-in-gas regulations. Because of the outcry from environmentalists and expert testimony from the medical community, the EPA reversed its policy and issued new standards which would reduce lead emissions between 1983 and 1990 by 34 percent (128,000 tons). Scientific evidence presented showed a clear reduction in blood lead levels from 1976-1980 which paralleled decreases of lead in gasoline. Results from lead poisoning clinics which linked chronic low lead exposures to decreased classroom performance and other learning disabilities were presented. Lawyers from several environmental groups took the agency to court on the related issue of attaining national ambient air quality standards for lead. (JMT)

  12. Lead in the environment

    USGS Publications Warehouse

    Pattee, O.H.; Pain, D.J.; Hoffman, David J.; Rattner, Barnett A.; Burton, G. Allen; Cairns, John=

    2003-01-01

    Anthropogenic uses of lead have probably altered its availability and environmental distribution more than any other toxic element. Consequently, lead concentrations in many living organisms may be approaching thresholds of toxicity for the adverse effects of lead. Such thresholds are difficult to define, as they vary with the chemical and physical form of lead, exposure regime, other elements present and also vary both within and between species. The technological capability to accurately quantify low lead concentrations has increased over the last decade, and physiological and behavioral effects have been measured in wildlife with tissue lead concentrations below those previously considered safe for humans.s.236 Consequently. lead criteria for the protection of wildlife and human health are frequently under review, and 'thresholds' of lead toxicity are being reconsidered. Proposed lead criteria for the protection of natural resources have been reviewed by Eisler. Uptake of lead by plants is limited by its generally low availability in soils and sediments, and toxicity may be limited by storage mechanisms and its apparently limited translocation within most plants. Lead does not generally accumulate within the foliar parts of plants, which limits its transfer to higher trophic levels. Although lead may concentrate in plant and animal tissues, no evidence of biomagnification exists. Acid deposition onto surface waters and soils with low buffering capacity may influence the availability of lead for uptake by plants and animals, and this may merit investigation at susceptible sites. The biological significance of chronic low-level lead exposure to wildlife is sometimes difficult to quantify. Animals living in urban environments or near point sources of lead emission are inevitably subject to greater exposure to lead and enhanced risk of lead poisoning. Increasingly strict controls on lead emissions in many countries have reduced exposure to lead from some sources

  13. Multimetallic Electrodeposition on Carbon Fibers

    NASA Astrophysics Data System (ADS)

    Böttger-Hiller, F.; Kleiber, J.; Böttger, T.; Lampke, T.

    2016-03-01

    Efficient lightweight design requires intelligent materials that meet versatile functions. One approach is to extend the range of properties of carbon fiber reinforced plastics (CFRP) by plating the fiber component. Electroplating leads to metalized layers on carbon fibers. Herein only cyanide-free electrolytes where used. Until now dendrite-free layers were only obtained using current densities below 1.0 A dm-2. In this work, dendrite-free tin and copper coatings were achieved by pre-metalizing the carbon fiber substrates. Furthermore, applying a combination of two metals with different sized thermal expansion coefficient lead to a bimetallic coating on carbon fiber rovings, which show an actuatory effect.

  14. Carbon tips for all-carbon single-molecule electronics.

    PubMed

    Dappe, Y J; González, C; Cuevas, J C

    2014-06-21

    We present here an exhaustive ab initio study of the use of carbon-based tips as electrodes in single-molecule junctions. Motivated by recent experiments, we show that carbon tips can be combined with other carbon nanostructures, such as graphene, to form all-carbon molecular junctions with molecules like benzene or C60. Our results show that the use of carbon tips can lead to relatively conductive molecular junctions. However, contrary to junctions formed with standard metals, the conductance traces recorded during the formation of the all-carbon single-molecule junctions do not exhibit clear conductance plateaus, which can be attributed to the inability of the hydrogenated carbon tips to form chemical bonds with the organic molecules. Additionally, we explore here the use of carbon tips for scanning tunneling microscopy and show that they are well suited for obtaining sample images with atomic resolution.

  15. Carbonate acidizing

    SciTech Connect

    Daccord, G.; Touboul, E.; Lenormand, R.

    1989-02-01

    The authors present the first quantitative study and complete model of the wormholing phenomenon, leading to a means of predicting and optimizing carbonate acidizing treatments. Laboratory experiments on a gypsum model system and computer simulations show that for a given geometry, wormholes can be quantified by a unique parameter, their equivalent hydraulic length. The behavior of this quantifying parameter vs. all the system parameters is studied and allows the quantitative prediction of the efficiency of an acidizing treatment. This study highlights the fractal nature of the phenomenon, which is accounted for in the equations, and the strong effect of the sample geometry. Three types of etching can be obtained: compact, wormhole type, or homogeneous. The optimum conditions for achieving the best skin decrease correspond to the creation of wormholes and can then be defined in terms of fluid reactivity and injection rate.

  16. Lead in candle emissions.

    PubMed

    Wasson, Shirley J; Guo, Zhishi; McBrian, Jenia A; Beach, Laura O

    2002-09-16

    The candle-using public should be made aware that the core of candle wicks may contain lead. Used as a stiffening agent to keep the wick out of the molten wax, lead can be emitted as particulates to the air and then deposited on indoor surfaces. To define the problem, 100 sets of candles (two or more identical candles) were purchased locally. The criterion for purchase was that the candles must appear to contain a metal-cored wick or be covered by a metallic pigment. Of the candles purchased, 8% contained lead wicks. The wicks were 39-74% lead (the remainder was fabric or paper) and the lead cores (approx. 100% lead) had linear densities of 13-27 mg/cm. Candles were burned to completion in a closed chamber to capture the air emissions, and the candle residue was extracted to assess the lead mass balance. It was found that individual candles emitted lead to the air at average rates that ranged from 100 to 1700 microg/h. Assuming realistic indoor conditions, these emission rates were modeled to project room air concentration, child exposure by inhalation, and indoor deposition. Results showed that burning single candles can easily raise the source room concentration above the ambient air lead concentration limit of 1.5 microg/m3 set by EPA. Burning multiple candles can elevate it above OSHA permissible exposure limits of 50 microg/m3. Although blood lead levels have dropped precipitously in the United States since lead was phased out of gasoline in 1986, nearly 900,000 children still had levels above 10 microg/dl during NHANES III. Considering that candle sales in the US are estimated at $1-2 billion per year, and that children may spend as much as 88% of their time indoors, it is reasonable to suspect that some blood lead elevation in children arises from indoor micro-environments where lead-wick candles are burned.

  17. Development of Columbia Leading Edge Reconstruction System

    NASA Technical Reports Server (NTRS)

    Trautwein, John; Wegerif, Dan

    2004-01-01

    After the loss of Columbia in 2003, the Columbia Accident Investigation Board and NASA KSC directed personnel at the Launch Equipment Test Facility (LETF) to design and build high fidelity mock-ups of Columbia's left wing leading edges. These leading edge segments, constructed of reinforced carbon-carbon, were a major point of inquiry by the investigation team. The LETF engineers developed a concept of building a clear Lexan panel with an aluminum support structure ten percent larger than the original panel. The leading edge debris are attached to the Lexan panels and both the front and back side of each panel are visible for inspection. The entire assembly can be rotated, to provide visual access to the entire panel. Six carts were fabricated to support the thirteen panels. These carts could be set up in order, next to each other, to provide the desired inspection access. The carts and attached debris are currently located in the Vehicle Assembly Building at KSC.

  18. Preconcentration and extraction of lead ions in vegetable and water samples by N-doped carbon quantum dot conjugated with Fe3O4 as a green and facial adsorbent.

    PubMed

    Mashkani, Masoumeh; Mehdinia, Ali; Jabbari, Ali; Bide, Yasamin; Nabid, Mohammad Reza

    2018-01-15

    Magnetically N-doped Carbon quantum dots has been synthesized via a simple chemical method and applied as a sorbent for the preconcentration and extraction of trace amounts of Pb(2+) from water and vegetable samples followed by flame atomic absorption spectrometric detection. The nanoparticles were characterized by X-ray diffraction, UV-vis spectra, Fourier transform infrared spectroscopy, vibrating sample magnetometer analysis and transmission electron microscopy. A central-composite design was used to find the optimum conditions for the preconcentration procedure through response surface methodology. The effects of various parameters such as the pH value, adsorption time, amount of adsorbent, desorption conditions (type, concentration and volume of the eluent and desorption time), sample volume and interfering ions have been studied. Under the optimized conditions, the calibration graph was linear in the range of 0.3-300μgL(-1) (R(2)=9992). The detection limit and pre-concentration factor were found to be 0.082μgL(-1) and 265, respectively. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. Multi-walled carbon nanotubes (MWCNTs) lead to growth retardation, antioxidant depletion, and activation of the ERK signaling pathway but decrease copper bioavailability in the monogonont rotifer (Brachionus koreanus).

    PubMed

    Lee, Jin Wuk; Kang, Hye-Min; Won, Eun-Ji; Hwang, Dae-Sik; Kim, Duck-Hyun; Lee, Su-Jae; Lee, Jae-Seong

    2016-03-01

    To examine the toxic effects of multi-walled carbon nanotubes (MWCNTs) in the marine environment, we first exposed the monogonont rotifer (Brachionus koreanus) to MWCNTs in the presence of copper. The acute toxicity of copper decreased significantly with a decrease in copper bioavailability resulting from MWCNT exposure. Furthermore, we examined the effects of MWCNT exposure on reproductive capacity, population growth rate, growth patterns, antioxidant systems, and mitogen-activated protein kinase (MAPK) activation. Reproductive capacity, population growth rate, and body growth rate were significantly suppressed in B. koreanus in response to 1.3-4mg/L MWCNT exposure. Furthermore, MWCNTs induced the generation of reactive oxygen species (ROS) and decreased the antioxidant enzymatic activities of catalase (CAT) and glutathione reductase (GR). However, the enzymatic activity of glutathione S-transferase (GST) was up-regulated after a 24 h-exposure to 100mg/L MWCNTs. Exposure to 100mg/L MCWNTs induced extracellular signal-regulated kinase (ERK) activation in B. koreanus, suggesting that p-ERK may mediate the adverse effects of MWCNTs in B. koreanus via the MAPK signaling pathway. Our results provide insight into the mechanistic basis of the ecotoxicological effects of MWCNTs in the marine environment. Copyright © 2015 Elsevier B.V. All rights reserved.

  20. Carbon-carbon cylinder block

    NASA Technical Reports Server (NTRS)

    Ransone, Philip O. (Inventor)

    1998-01-01

    A lightweight cylinder block composed of carbon-carbon is disclosed. The use of carbon-carbon over conventional materials, such as cast iron or aluminum, reduces the weight of the cylinder block and improves thermal efficiency of the internal combustion reciprocating engine. Due to the negligible coefficient of thermal expansion and unique strength at elevated temperatures of carbon-carbon, the piston-to-cylinder wall clearance can be small, especially when the carbon-carbon cylinder block is used in conjunction with a carbon-carbon piston. Use of the carbon-carbon cylinder block has the effect of reducing the weight of other reciprocating engine components allowing the piston to run at higher speeds and improving specific engine performance.

  1. Carbon-carbon cylinder block

    NASA Technical Reports Server (NTRS)

    Ransone, Philip O. (Inventor)

    1995-01-01

    A lightweight cylinder block composed of carbon-carbon is disclosed. The use of carbon-carbon over conventional materials, such as cast iron or aluminum, reduces the weight of the cylinder block and improves thermal efficiency of the internal combustion reciprocating engine. Due to the negligible coefficient of thermal expansion and unique strength at elevated temperatures of carbon-carbon, the piston-to-cylinder wall clearance can be small, especially when the carbon-carbon cylinder block is used in conjunction with a carbon-carbon piston. Use of the carbon-carbon cylinder has the effect of reducing the weight of other reciprocating engine components allowing the piston to run at higher speeds and improving specific engine performance.

  2. Lead Poison Detection

    NASA Technical Reports Server (NTRS)

    1976-01-01

    With NASA contracts, Whittaker Corporations Space Science division has developed an electro-optical instrument to mass screen for lead poisoning. Device is portable and detects protoporphyrin in whole blood. Free corpuscular porphyrins occur as an early effect of lead ingestion. Also detects lead in urine used to confirm blood tests. Test is inexpensive and can be applied by relatively unskilled personnel. Similar Whittaker fluorometry device called "drug screen" can measure morphine and quinine in urine much faster and cheaper than other methods.

  3. [Familial lead poisoning].

    PubMed

    Ríos, E; Dal Borgo, P; Riveros, A; Díaz, S M

    1989-06-01

    A 1 year and 9 month old patient was admitted with ataxia. CBC showed a microcytic, hypocromic anemia with intense basophilic sttipling of erythrocytes. Lead poisoning was suspected and confirmed with a blood lead level of 167 micrograms/dl. The patient was treated with EDTA and BAL. It was discovered that family burned old car batteries for food cooking. Four members were intoxicated, with blood lead levels at or above 50 micrograms/dl.

  4. Catalytically active lead(ii)-imidazolium coordination assemblies with diversified lead(ii) coordination geometries.

    PubMed

    Naga Babu, Chatla; Suresh, Paladugu; Srinivas, Katam; Sathyanarayana, Arruri; Sampath, Natarajan; Prabusankar, Ganesan

    2016-05-10

    Five Pb(ii)-imidazolium carboxylate coordination assemblies with novel structural motifs were derived from the reaction between the corresponding flexible, semi flexible or rigid imidazolium carboxylic acid ligands and lead nitrate. The imidazolium linker present in these molecules likely plays a triple role such as the counter ion to balance the metal charge, the ligand being an integral part of the final product and the catalyst facilitating carbon-carbon bond formation reaction. These lead-imidazolium coordination assemblies exhibit, variable chemical and thermal stabilities, as well as catalytic activity. These newly prepared catalysts are highly active towards benzoin condensation reactions with good functional group tolerance.

  5. Immunosuppressive effects of lead

    USGS Publications Warehouse

    Franson, J. Christian; Feierabend, J.Scott; Russell, A.Brooke

    1986-01-01

    Immunosuppressive effects of lead were reported as early as 1966, when it was noted that lead increased the sensitivity of rats to bacterial endotoxins (Selye et al. 1966). Since then a substantial body of literature has demonstrated adverse effects of lead on the immune system in a variety of laboratory animals, but very little has been done in this area with avian species. Such immunosuppressive effects could be of significance to waterfowl populations, considering the potential for lead ingestion by waterfowl and subsequent exposure of these birds to disease agents.

  6. Lead poisoning: case studies.

    PubMed

    Gordon, J N; Taylor, A; Bennett, P N

    2002-05-01

    Early clinical features of lead toxicity are non-specific and an occupational history is particularly valuable. Lead in the body comprises 2% in the blood (t1/2 35 days) and 95% in bone and dentine (t1/2 20-30 years). Blood lead may remain elevated for years after cessation from long exposure, due to redistribution from bone. Blood lead concentration is the most widely used marker for inorganic lead exposure. Zinc protoporphyrin (ZPP) concentration in blood usefully reflects lead exposure over the prior 3 months. Symptomatic patients with blood lead concentration >2.4 micromol l-1 (50 microg dl-1) or in any event >3.8 micromol l-1 (80 microg dl-1) should receive sodium calciumedetate i.v., followed by succimer by mouth for 19 days. Asymptomatic patients with blood lead concentration >2.4 micromol l-1 (50 microg dl-1) may be treated with succimer alone. Sodium calciumedetate should be given with dimercaprol to treat lead encephalopathy.

  7. Immunosuppressive effects of lead

    USGS Publications Warehouse

    Franson, J. Christian; Feierabend, J.Scott; Russell, A.Brooke

    1986-01-01

    Immunosuppressive effects of lead were reported as early as 1966, when it was noted that lead increased the sensitivity of rats to bacterial endotoxins (Selye et al. 1966). Since then a substantial body of literature has demonstrated adverse effects of lead on the immune system in a variety of laboratory animals, but very little has been done in this area with avian species. Such immunosuppressive effects could be of significance to waterfowl populations, considering the potential for lead ingestion by waterfowl and subsequent exposure of these birds to disease agents.

  8. Acute lead arsenate poisoning.

    PubMed

    Tallis, G A

    1989-12-01

    Three cases of acute lead arsenate poisoning which occurred in South Australia during a 12 month interval are described. The case reports demonstrate a number of features of the characteristic clinical syndrome which may follow ingestion of lead arsenate. The recommended management is immediate gastric lavage and subsequent chelation therapy with calcium EDTA and dimercaprol. Early gastric lavage may prevent significant lead absorption. However, arsenic acid (produced in the stomach when lead arsenate reacts with hydrochloric acid) is relatively water soluble and prompt gastric lavage is unlikely to prevent extensive arsenic absorption. It remains controversial as to whether chelation with dimercaprol prevents arsenical neuropathy.

  9. Global climate change and pedogenic carbonates

    SciTech Connect

    Lal, R.; Kimble, J.M.; Stewart, B.A.; Eswaran, H.

    1999-11-01

    Global Climate Change summarizes what is known about soil inorganic carbon and develops strategies that could lead to the retention of more carbon in the soil. It covers basic concepts, analytical methods, secondary carbonates, and research and development priorities. With this book one will get a better understanding of the global carbon cycle, organic and inorganic carbon, and their roles, or what is known of them, in the greenhouse effect.

  10. Experimental lead poisoning in the baboon

    PubMed Central

    Hopkins, Anthony

    1970-01-01

    Hopkins, A. (1970).Brit. J. industr. Med.,27, 130-140. Experimental lead poisoning in the baboon. Twelve large and three infant baboons were poisoned by the intratracheal injection of lead carbonate in doses ranging from 50 to 135 mg/kg for 39 to 362 days. Eight baboons had one or more epileptic fits. Weakness of the limbs, believed to be of central origin, was seen in three of them. The effect of single and multiple doses of lead on the blood lead is recorded. Anaemia and punctate basophilia were not found. Measurements of nerve conduction velocity, electromyography and histological examination showed no abnormality of the peripheral nerves. The different effects of lead upon different species are discussed. Images PMID:4987891

  11. Childhood lead poisoning.

    PubMed

    Linakis, J G

    1995-01-01

    Lead poisoning has been referred to as the most important environmental health hazard for children in New England. Medical professionals are in a unique position to perform a number of interventions that could make a lasting impact. First, physicians and nurses, particularly in the areas of pediatrics and family medicine, can provide anticipatory guidance to all families with young children. Lead poisoning, in contrast to long held beliefs, is an affliction that affects all socioeconomic groups. Parents should thus be informed regarding sources of lead, including occupational and hobby sources, and basic nutritional and abatement information should be provided. Second, health care workers should encourage lead screening in appropriately aged children at recommended intervals based on known risk factors. Once a blood lead concentration greater than 20[symbol: see text]g/dl has been obtained in a child, treatment or referral to an established lead clinic should be undertaken in a timely fashion. For children with low or moderate lead levels, many pediatricians or family physicians prefer to supervise their patients' treatment, including chelation therapy. For children with higher levels or in instances when the health care professional elects to refer, there are several lead clinics throughout New England whose clinicians are experienced in the treatment of childhood lead poisoning. Finally the medical profession needs to publicly recognize, as child advocates, that lead poisoning is one of the most common pediatric health problems in the United States and that it is entirely preventable. Fortunately, after many years and much hard work, Rhode Island finally has laws that start to deal with the lead problem in an appropriately aggressive fashion.(ABSTRACT TRUNCATED AT 250 WORDS)

  12. Solid substrate-room temperature phosphorimetry for the determination of trace lead using p-nitro-phenyl-fluorone-multi-wall carbon nanotubes-Tween-80 micellae compound and diagnosis about human diseases

    NASA Astrophysics Data System (ADS)

    Tianlong, Yang; Zhenbo, Liu; Jiaming, Liu; Haizhu, Liu; Yahong, Huang; Jianqin, Liu; Xuebing, Chen; Yibing, Zhao

    2009-02-01

    The structures of multi-wall carbon nanotubes (MWNTs) were modified by H 2SO 4-HNO 3 and H 2SO 4-H 2O 2, respectively. The corresponding products were water-soluble MWNTs-A and MWNTs-B. According to the experiment, it was found that MWNTs-B could emit stable solid substrate-room temperature phosphorescence (RTP) on the surface of paper with Ag + as perturber. Under the conditions of 70 °C and 15 min, MWNTs-B can react with Tween-80 and p-nitro-phenyl-fluorone (R) to form R-MWNTs-B-Tween-80 micellae compound, which could emit RTP of R and MWNTs-B on the surface of paper, respectively. Pb 2+ could cause the RTP of R and MWNTs-B enhanced sharply, respectively. Δ Ip is directly proportional to the content of Pb 2+. A new solid substrate-room temperature phosphorimetry (SS-RTP) for the determination of trace Pb 2+ has been established based on R-MWNTs-B-Tween-80 micellae compound containing double luminescent molecule. The detection limit of this method were 0.035 ag Pb 2+ spot -1 (8.8 × 10 -17 g Pb 2+ ml -1, MWNTs-B) and 0.028 ag Pb 2+ spot -1 (7.1 × 10 -17 g Pb 2+ ml -1, R). This method is of high sensitivity, good selectivity, high precision and accuracy. It could be applied to determine trace Pb 2+ in serum samples at wavelength of 453.7/623.0 nm (R) or 475.9/645.0 nm (MWNTs-B) with satisfactory results, showing that SS-RTP has flexibility and utility value. Simultaneously, this method can be used to diagnose human diseases. The reaction mechanism for the determination of trace Pb 2+ by SS-RTP based on R-MWNTs-B-Tween-80 micellae compound containing double luminescent molecule was also discussed.

  13. LEAD IN CANDLE EMISSIONS

    EPA Science Inventory

    The candle-using public should be made aware that the core of candle wicks may contain lead. Used as a stiffening agent to keep the wick out of the molten wax, lead can be emitted as particulate to the air and then deposited on indoor surfaces. To define the problem, 100 sets of ...

  14. Supersonic Leading Edge Receptivity

    NASA Technical Reports Server (NTRS)

    Maslov, Anatoly A.

    1998-01-01

    This paper describes experimental studies of leading edge boundary layer receptivity for imposed stream disturbances. Studies were conducted in the supersonic T-325 facility at ITAM and include data for both sharp and blunt leading edges. The data are in agreement with existing theory and should provide guidance for the development of more complete theories and numerical computations of this phenomena.

  15. Rapid Lead Screening Test

    MedlinePlus

    ... and treated earlier before the damaging effects of lead poisoning occur. U.S. Department of Health and Human Services ... exceed 10μg/dL, the threshold used to indicate lead poisoning. The American Academy of Pediatrics (AAP) estimates one ...

  16. Lead Poisoning in Children.

    ERIC Educational Resources Information Center

    Lin-Fu, Jane S.

    This publication is a guide to help social and health workers plan a preventive campaign against lead poisoning, a cause of mental retardation other neurological handicaps, and death among children. The main victims are 1- to 6-year-olds living in areas where deteriorating housing prevails. Among the causes of lead poisoning are: ingestion of…

  17. Lead toxicity: a review

    PubMed Central

    Ara, Anjum; Usmani, Jawed Ahmad

    2015-01-01

    Lead toxicity is an important environmental disease and its effects on the human body are devastating. There is almost no function in the human body which is not affected by lead toxicity. Though in countries like US and Canada the use of lead has been controlled up to a certain extent, it is still used vehemently in the developing countries. This is primarily because lead bears unique physical and chemical properties that make it suitable for a large number of applications for which humans have exploited its benefits from historical times and thus it has become a common environmental pollutant. Lead is highly persistent in the environment and because of its continuous use its levels rise in almost every country, posing serious threats. This article reviews the works listed in the literature with recent updates regarding the toxicity of lead. Focus is also on toxic effects of lead on the renal, reproductive and nervous system. Finally the techniques available for treating lead toxicity are presented with some recent updates. PMID:27486361

  18. Lead Poisoning (For Parents)

    MedlinePlus

    ... blood cells and limit their ability to carry oxygen to the organs and tissues that need it, thus causing anemia. Most lead ends up in the bone, where it causes even more problems. Lead can interfere with the production of blood cells and the absorption of calcium ...

  19. Lead toxicity: a review.

    PubMed

    Wani, Ab Latif; Ara, Anjum; Usmani, Jawed Ahmad

    2015-06-01

    Lead toxicity is an important environmental disease and its effects on the human body are devastating. There is almost no function in the human body which is not affected by lead toxicity. Though in countries like US and Canada the use of lead has been controlled up to a certain extent, it is still used vehemently in the developing countries. This is primarily because lead bears unique physical and chemical properties that make it suitable for a large number of applications for which humans have exploited its benefits from historical times and thus it has become a common environmental pollutant. Lead is highly persistent in the environment and because of its continuous use its levels rise in almost every country, posing serious threats. This article reviews the works listed in the literature with recent updates regarding the toxicity of lead. Focus is also on toxic effects of lead on the renal, reproductive and nervous system. Finally the techniques available for treating lead toxicity are presented with some recent updates.

  20. LEAD IN CANDLE EMISSIONS

    EPA Science Inventory

    The candle-using public should be made aware that the core of candle wicks may contain lead. Used as a stiffening agent to keep the wick out of the molten wax, lead can be emitted as particulate to the air and then deposited on indoor surfaces. To define the problem, 100 sets of ...

  1. Bonding aluminum beam leads

    NASA Technical Reports Server (NTRS)

    Burkett, F. S.

    1978-01-01

    Report makes it relatively easy for hybrid-circuit manufacturers to convert integrated circuit chips with aluminum bead leads. Report covers: techniques for handling tiny chips; proper geometries for ultrasonic bonding tips; best combinations of pressure, pulse time, and ultrasonic energy for bonding; and best thickness for metal films to which beam leads are bonded.

  2. Carbon Smackdown: Carbon Capture

    SciTech Connect

    Jeffrey Long

    2010-07-12

    In this July 9, 2010 Berkeley Lab summer lecture, Lab scientists Jeff Long of the Materials Sciences and Nancy Brown of the Environmental Energy Technologies Division discuss their efforts to fight climate change by capturing carbon from the flue gas of power plants, as well as directly from the air

  3. Carbon Smackdown: Carbon Capture

    ScienceCinema

    Jeffrey Long

    2016-07-12

    In this July 9, 2010 Berkeley Lab summer lecture, Lab scientists Jeff Long of the Materials Sciences and Nancy Brown of the Environmental Energy Technologies Division discuss their efforts to fight climate change by capturing carbon from the flue gas of power plants, as well as directly from the air

  4. KENNEDY SPACE CENTER, FLA. - NASA Vehicle Manager Scott Thurston (right) talks to the media in the Orbiter Processing Facility . The media was invited to see the orbiter Atlantis as it is being prepared for Return to Flight. Both local and national reporters representing print and TV networks were able to see work in progress on Atlantis, including the reinstallation of the Reinforced Carbon-Carbon panels on the orbiter’s wing leading edge; wiring inspections; and checks of the engines in the Orbital Maneuvering System.

    NASA Image and Video Library

    2003-09-26

    KENNEDY SPACE CENTER, FLA. - NASA Vehicle Manager Scott Thurston (right) talks to the media in the Orbiter Processing Facility . The media was invited to see the orbiter Atlantis as it is being prepared for Return to Flight. Both local and national reporters representing print and TV networks were able to see work in progress on Atlantis, including the reinstallation of the Reinforced Carbon-Carbon panels on the orbiter’s wing leading edge; wiring inspections; and checks of the engines in the Orbital Maneuvering System.

  5. KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility (OPF), Rick Beckwith, an orbiter engineer with United Space Alliance, explains to the media the reinstallation of the Reinforced Carbon-Carbon panels on Atlantis’ wing leading edge. The media was invited to tour the OPF at KSC and to see the orbiter Atlantis as it is being prepared for Return to Flight. Both local and national reporters representing print and TV networks were able to see work in progress on Atlantis, also including wiring inspections and checks of the engines in the Orbital Maneuvering System.

    NASA Image and Video Library

    2003-09-26

    KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility (OPF), Rick Beckwith, an orbiter engineer with United Space Alliance, explains to the media the reinstallation of the Reinforced Carbon-Carbon panels on Atlantis’ wing leading edge. The media was invited to tour the OPF at KSC and to see the orbiter Atlantis as it is being prepared for Return to Flight. Both local and national reporters representing print and TV networks were able to see work in progress on Atlantis, also including wiring inspections and checks of the engines in the Orbital Maneuvering System.

  6. KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility (OPF), Rick Beckwith, an orbiter engineer with United Space Alliance, explains to the media the reinstallation of the Reinforced Carbon-Carbon panels on the orbiter Atlantis’ wing leading edge. The media was invited to tour the OPF at KSC and to see the orbiter Atlantis as it is being prepared for Return to Flight. Both local and national reporters representing print and TV networks were able to see work in progress on Atlantis, also including wiring inspections and checks of the engines in the Orbital Maneuvering System.

    NASA Image and Video Library

    2003-09-26

    KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility (OPF), Rick Beckwith, an orbiter engineer with United Space Alliance, explains to the media the reinstallation of the Reinforced Carbon-Carbon panels on the orbiter Atlantis’ wing leading edge. The media was invited to tour the OPF at KSC and to see the orbiter Atlantis as it is being prepared for Return to Flight. Both local and national reporters representing print and TV networks were able to see work in progress on Atlantis, also including wiring inspections and checks of the engines in the Orbital Maneuvering System.

  7. KENNEDY SPACE CENTER, FLA. - The media gather around NASA Vehicle Manager Scott Thurston (white shirt, right) who talks about some of the work being done on the orbiter Atlantis as it is being prepared for Return to Flight in the Orbiter Processing Facility. Both local and national reporters representing print and TV networks were able to see work in progress on Atlantis, including the reinstallation of the Reinforced Carbon-Carbon panels on the orbiter’s wing leading edge; wiring inspections; and checks of the engines in the Orbital Maneuvering System.

    NASA Image and Video Library

    2003-09-26

    KENNEDY SPACE CENTER, FLA. - The media gather around NASA Vehicle Manager Scott Thurston (white shirt, right) who talks about some of the work being done on the orbiter Atlantis as it is being prepared for Return to Flight in the Orbiter Processing Facility. Both local and national reporters representing print and TV networks were able to see work in progress on Atlantis, including the reinstallation of the Reinforced Carbon-Carbon panels on the orbiter’s wing leading edge; wiring inspections; and checks of the engines in the Orbital Maneuvering System.

  8. KENNEDY SPACE CENTER, FLA. - NASA Vehicle Manager Scott Thurston (hands extended) talks to the media in the Orbiter Processing Facility. The media was invited to see the orbiter Atlantis as it is being prepared for Return to Flight. Both local and national reporters representing print and TV networks were able to see work in progress on Atlantis, including the reinstallation of the Reinforced Carbon-Carbon panels on the orbiter’s wing leading edge; wiring inspections; and checks of the engines in the Orbital Maneuvering System.

    NASA Image and Video Library

    2003-09-26

    KENNEDY SPACE CENTER, FLA. - NASA Vehicle Manager Scott Thurston (hands extended) talks to the media in the Orbiter Processing Facility. The media was invited to see the orbiter Atlantis as it is being prepared for Return to Flight. Both local and national reporters representing print and TV networks were able to see work in progress on Atlantis, including the reinstallation of the Reinforced Carbon-Carbon panels on the orbiter’s wing leading edge; wiring inspections; and checks of the engines in the Orbital Maneuvering System.

  9. KENNEDY SPACE CENTER, FLA. - NASA Vehicle Manager Scott Thurston (right) talks to the media in the Orbiter Processing Facility. The media was invited to see the orbiter Atlantis as it is being prepared for Return to Flight. Both local and national reporters representing print and TV networks were able to see work in progress on Atlantis, including the reinstallation of the Reinforced Carbon-Carbon panels on the orbiter’s wing leading edge; wiring inspections; and checks of the engines in the Orbital Maneuvering System. will be available to discuss the work and answer questions.

    NASA Image and Video Library

    2003-09-26

    KENNEDY SPACE CENTER, FLA. - NASA Vehicle Manager Scott Thurston (right) talks to the media in the Orbiter Processing Facility. The media was invited to see the orbiter Atlantis as it is being prepared for Return to Flight. Both local and national reporters representing print and TV networks were able to see work in progress on Atlantis, including the reinstallation of the Reinforced Carbon-Carbon panels on the orbiter’s wing leading edge; wiring inspections; and checks of the engines in the Orbital Maneuvering System. will be available to discuss the work and answer questions.

  10. KENNEDY SPACE CENTER, FLA. - NASA Vehicle Manager Scott Thurston (facing camera) talks to the media in the Orbiter Processing Facility. The media was invited to see the orbiter Atlantis as it is being prepared for Return to Flight. Both local and national reporters representing print and TV networks were able to see work in progress on Atlantis, including the reinstallation of the Reinforced Carbon-Carbon panels on the orbiter’s wing leading edge; wiring inspections; and checks of the engines in the Orbital Maneuvering System.

    NASA Image and Video Library

    2003-09-26

    KENNEDY SPACE CENTER, FLA. - NASA Vehicle Manager Scott Thurston (facing camera) talks to the media in the Orbiter Processing Facility. The media was invited to see the orbiter Atlantis as it is being prepared for Return to Flight. Both local and national reporters representing print and TV networks were able to see work in progress on Atlantis, including the reinstallation of the Reinforced Carbon-Carbon panels on the orbiter’s wing leading edge; wiring inspections; and checks of the engines in the Orbital Maneuvering System.

  11. KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, the media photograph work being done on the tiles on the orbiter Atlantis as it is being prepared for Return to Flight in the Orbiter Processing Facility. Both local and national reporters representing print and TV networks were able to see work in progress on Atlantis, including the reinstallation of the Reinforced Carbon-Carbon panels on the orbiter’s wing leading edge; wiring inspections; and checks of the engines in the Orbital Maneuvering System.

    NASA Image and Video Library

    2003-09-26

    KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, the media photograph work being done on the tiles on the orbiter Atlantis as it is being prepared for Return to Flight in the Orbiter Processing Facility. Both local and national reporters representing print and TV networks were able to see work in progress on Atlantis, including the reinstallation of the Reinforced Carbon-Carbon panels on the orbiter’s wing leading edge; wiring inspections; and checks of the engines in the Orbital Maneuvering System.

  12. KENNEDY SPACE CENTER, FLA. - NASA Vehicle Manager Scott Thurston talks to the media in the Orbiter Processing Facility. The media was invited to see the orbiter Atlantis as it is being prepared for Return to Flight. Both local and national reporters representing print and TV networks were able to see work in progress on Atlantis, including the reinstallation of the Reinforced Carbon-Carbon panels on the orbiter’s wing leading edge; wiring inspections; and checks of the engines in the Orbital Maneuvering System.

    NASA Image and Video Library

    2003-09-26

    KENNEDY SPACE CENTER, FLA. - NASA Vehicle Manager Scott Thurston talks to the media in the Orbiter Processing Facility. The media was invited to see the orbiter Atlantis as it is being prepared for Return to Flight. Both local and national reporters representing print and TV networks were able to see work in progress on Atlantis, including the reinstallation of the Reinforced Carbon-Carbon panels on the orbiter’s wing leading edge; wiring inspections; and checks of the engines in the Orbital Maneuvering System.

  13. KENNEDY SPACE CENTER, FLA. - NASA Vehicle Manager Scott Thurston (left) talks to a phalanx of media in the Orbiter Processing Facility. The media was invited to see the orbiter Atlantis as it is being prepared for Return to Flight. Both local and national reporters representing print and TV networks were able to see work in progress on Atlantis, including the reinstallation of the Reinforced Carbon-Carbon panels on the orbiter’s wing leading edge; wiring inspections; and checks of the engines in the Orbital Maneuvering System.

    NASA Image and Video Library

    2003-09-26

    KENNEDY SPACE CENTER, FLA. - NASA Vehicle Manager Scott Thurston (left) talks to a phalanx of media in the Orbiter Processing Facility. The media was invited to see the orbiter Atlantis as it is being prepared for Return to Flight. Both local and national reporters representing print and TV networks were able to see work in progress on Atlantis, including the reinstallation of the Reinforced Carbon-Carbon panels on the orbiter’s wing leading edge; wiring inspections; and checks of the engines in the Orbital Maneuvering System.

  14. KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, Rick Beckwith (center), an orbiter engineer with United Space Alliance, explains to the media the reinstallation of the Reinforced Carbon-Carbon panels on the orbiter Atlantis’ wing leading edge. The media was invited to tour the OPF at KSC and to see the orbiter Atlantis as it is being prepared for Return to Flight. Both local and national reporters representing print and TV networks were able to see work in progress on Atlantis, also including wiring inspections and checks of the engines in the Orbital Maneuvering System.

    NASA Image and Video Library

    2003-09-26

    KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, Rick Beckwith (center), an orbiter engineer with United Space Alliance, explains to the media the reinstallation of the Reinforced Carbon-Carbon panels on the orbiter Atlantis’ wing leading edge. The media was invited to tour the OPF at KSC and to see the orbiter Atlantis as it is being prepared for Return to Flight. Both local and national reporters representing print and TV networks were able to see work in progress on Atlantis, also including wiring inspections and checks of the engines in the Orbital Maneuvering System.

  15. KENNEDY SPACE CENTER, FLA. - Local Central Florida television reporters Phil Robertson (left), with WFTV, and Dan Billow (right), with WESH, tape commentaries after a media tour of the Orbiter Processing Facility. The media was invited to see the orbiter Atlantis as it is being prepared for Return to Flight. Both local and national reporters representing print and TV networks were able to see work in progress on Atlantis, including the reinstallation of the Reinforced Carbon-Carbon panels on the orbiter’s wing leading edge; wiring inspections; and checks of the engines in the Orbital Maneuvering System.

    NASA Image and Video Library

    2003-09-26

    KENNEDY SPACE CENTER, FLA. - Local Central Florida television reporters Phil Robertson (left), with WFTV, and Dan Billow (right), with WESH, tape commentaries after a media tour of the Orbiter Processing Facility. The media was invited to see the orbiter Atlantis as it is being prepared for Return to Flight. Both local and national reporters representing print and TV networks were able to see work in progress on Atlantis, including the reinstallation of the Reinforced Carbon-Carbon panels on the orbiter’s wing leading edge; wiring inspections; and checks of the engines in the Orbital Maneuvering System.

  16. Lead polluters get punished

    SciTech Connect

    Not Available

    1991-08-09

    The Environmental Protection Agency (EPA) and the Department of Justice last week cracked down on 36 US companies for polluting the environment with lead. EPA slapped fines totaling more than $10 million on 12 of the offending companies, and Justice filed 24 civil complaints. Hank Habicht, deputy administrator of the EPA, said that his agency's initiative comes after 8 months of intense - and presumably successful - efforts at locating and documenting lead pollution in the soil, air, and water supply. Most feared has been lead's ability to damage the intellectual development of children. This caused the agency, Habicht said, to look beyond the usual suspect - lead in the water supply - to lead-laced dirt in residential areas. Meanwhile, the Department of Justice is using the EPA contamination data as well. Twenty US attorneys have been assigned to pore over the federal environmental statutes, including the Clean Water Act and the Superfund Law, in order to file civil complaints.

  17. Lead contamination in Uruguay.

    PubMed

    Mañay, N; Pereira, L; Cousillas, Z

    1999-01-01

    Uruguay is a developing country of South America with about 3 million people, half of whom live in its principal city, Montevideo. This city has several lead pollution sources as emitting industries, most of them surrounded by residential neighborhoods, some still using lead pipes in drinking water systems of old buildings, and has areas of heavy traffic with cars that are still fueled with leaded gasoline. The toxic effects of this heavy metal are well known. Children are a very sensitive population and their early symptoms of intoxication are not always taken into account. Blood lead is a good indicator of recent exposure to lead influenced by inhalation and ingestion. The systematic data assessment of lead pollution and people exposure in Uruguay was not well known when the Department of Toxicology and Environmental Hygiene of the Faculty of Chemistry began to analyze lead in biological samples, first from exposed workers and next from children and the general population, including sensitive animal species like dogs. Several described studies were carried out analyzing for blood lead to assess lead uptake and to obtain reference values for Uruguayan populations. Since 1986, that Department is the only laboratory where blood lead analyses are done, and the analytical method has been controlled by an interlaboratory quality control program of the Ministry of Labour of Spain and confirmed by experts from the Laboratory of Occupational and Environmental Medicine of Lund, Sweden. Financial and technical support was obtained from Sweden (SAREC) and also from the University of the Republic of Uruguay. Uruguayan lead workers have always been the principally studied population because their lead exposure assessment as well as their health protection education is not always done properly. Uruguay has adopted ACGIH reference values (150 micrograms/m3 in total lead dust, 50 micrograms/m3 respirable lead dust, 300 micrograms/L blood), and the high blood lead levels indicate

  18. Lead toxicity: current concerns.

    PubMed Central

    Goyer, R A

    1993-01-01

    Over the 20-year period since the first issue of Environmental Health Perspectives was published, there has been considerable progress in the understanding of the potential toxicity of exposure to lead. Many of these advances have been reviewed in published symposia, conferences, and review papers in EHP. This brief review identifies major advances as well as a number of current concerns that present opportunities for prevention and intervention strategies. The major scientific advance has been the demonstration that blood lead (PbB) levels of 10-15 micrograms/dL in newborn and very young infants result in cognitive and behavioral deficits. Further support for this observation is being obtained by prospective or longitudinal studies presently in progress. The mechanism(s) for the central nervous system effects of lead is unclear but involve lead interactions within calcium-mediated intracellular messenger systems and neurotransmission. Effects of low-level lead exposure on blood pressure, particularly in adult men, may be related to the effect of lead on calcium-mediated control of vascular smooth muscle contraction and on the renin-angiotensin system. Reproductive effects of lead have long been suspected, but low-level effects have not been well studied. Whether lead is a carcinogen or its association with renal adenocarcinoma is a consequence of cystic nephropathy is uncertain. Major risk factors for lead toxicity in children in the United States include nutrition, particularly deficiencies of essential metals, calcium, iron, and zinc, and housing and socioeconomic status. A goal for the year 2000 is to reduce prevalence of blood lead levels exceeding 15 micrograms/dL. Images FIGURE 2. PMID:8354166

  19. Lead toxicity: Current concerns

    SciTech Connect

    Goyer, R.A. )

    1993-04-01

    Over the 20-year period since the first issue of Environmental Health Perspectives was published, there has been considerable progress in the understanding of the potential toxicity of exposure to lead. Many of these advances have been reviewed in published symposia, conferences, and review papers in EHP. This brief review identifies major advances as well as a number of current concerns that present opportunities for prevention and intervention strategies. The major scientific advance has been the demonstration that blood lead (PbB) levels of 10-15 micrograms/dL in newborn and very young infants result in cognitive and behavioral deficits. Further support for this observation is being obtained by prospective or longitudinal studies presently in progress. The mechanism(s) for the central nervous system effects of lead is unclear but involve lead interactions within calcium-mediated intracellular messenger systems and neurotransmission. Effects of low-level lead exposure on blood pressure, particularly in adult men, may be related to the effect of lead on calcium-mediated control of vascular smooth muscle contraction and on the renin-angiotensin system. Reproductive effects of lead have long been suspected, but low-level effects have not been well studied. Whether lead is a carcinogen or its association with renal adenocarcinoma is a consequence of cystic nephropathy is uncertain. Major risk factors for lead toxicity in children in the United States include nutrition, particularly deficiencies of essential metals, calcium, iron, and zinc, and housing and socioeconomic status. A goal for the year 2000 is to reduce prevalence of blood lead levels exceeding 15 micrograms/dL. 97 refs.

  20. Carbon isotopes in mollusk shell carbonates

    NASA Astrophysics Data System (ADS)

    McConnaughey, Ted A.; Gillikin, David Paul

    2008-10-01

    Mollusk shells contain many isotopic clues about calcification physiology and environmental conditions at the time of shell formation. In this review, we use both published and unpublished data to discuss carbon isotopes in both bivalve and gastropod shell carbonates. Land snails construct their shells mainly from respired CO2, and shell δ13C reflects the local mix of C3 and C4 plants consumed. Shell δ13C is typically >10‰ heavier than diet, probably because respiratory gas exchange discards CO2, and retains the isotopically heavier HCO3 -. Respired CO2 contributes less to the shells of aquatic mollusks, because CO2/O2 ratios are usually higher in water than in air, leading to more replacement of respired CO2 by environmental CO2. Fluid exchange with the environment also brings additional dissolved inorganic carbon (DIC) into the calcification site. Shell δ13C is typically a few ‰ lower than ambient DIC, and often decreases with age. Shell δ13C retains clues about processes such as ecosystem metabolism and estuarine mixing. Ca2+ ATPase-based models of calcification physiology developed for corals and algae likely apply to mollusks, too, but lower pH and carbonic anhydrase at the calcification site probably suppress kinetic isotope effects. Carbon isotopes in biogenic carbonates are clearly complex, but cautious interpretation can provide a wealth of information, especially after vital effects are better understood.

  1. Solid substrate-room temperature phosphorimetry for the determination of trace lead using p-nitro-phenyl-fluorone-multi-wall carbon nanotubes-Tween-80 micellae compound and diagnosis about human diseases.

    PubMed

    Yang, Tianlong; Liu, Zhenbo; Liu, Jiaming; Liu, Haizhu; Huang, Yahong; Liu, Jianqin; Chen, Xuebing; Zhao, Yibing

    2009-02-01

    The structures of multi-wall carbon nanotubes (MWNTs) were modified by H(2)SO(4)-HNO(3) and H(2)SO(4)-H(2)O(2), respectively. The corresponding products were water-soluble MWNTs-A and MWNTs-B. According to the experiment, it was found that MWNTs-B could emit stable solid substrate-room temperature phosphorescence (RTP) on the surface of paper with Ag(+) as perturber. Under the conditions of 70 degrees C and 15 min, MWNTs-B can react with Tween-80 and p-nitro-phenyl-fluorone (R) to form R-MWNTs-B-Tween-80 micellae compound, which could emit RTP of R and MWNTs-B on the surface of paper, respectively. Pb(2+) could cause the RTP of R and MWNTs-B enhanced sharply, respectively. DeltaI(p) is directly proportional to the content of Pb(2+). A new solid substrate-room temperature phosphorimetry (SS-RTP) for the determination of trace Pb(2+) has been established based on R-MWNTs-B-Tween-80 micellae compound containing double luminescent molecule. The detection limit of this method were 0.035 ag Pb(2+) spot(-1) (8.8 x 10(-17) g Pb(2+) ml(-1), MWNTs-B) and 0.028 ag Pb(2+) spot(-1) (7.1 x 10(-17) g Pb(2+) ml(-1), R). This method is of high sensitivity, good selectivity, high precision and accuracy. It could be applied to determine trace Pb(2+) in serum samples at wavelength of 453.7/623.0 nm (R) or 475.9/645.0 nm (MWNTs-B) with satisfactory results, showing that SS-RTP has flexibility and utility value. Simultaneously, this method can be used to diagnose human diseases. The reaction mechanism for the determination of trace Pb(2+) by SS-RTP based on R-MWNTs-B-Tween-80 micellae compound containing double luminescent molecule was also discussed.

  2. As-Fabricated Reinforced Carbon/Carbon Characterized

    NASA Technical Reports Server (NTRS)

    Jacobson, Nathan S.; Calomino, Anthony M.; Webster, Neal

    2004-01-01

    Reinforced carbon/carbon (RCC) is a critical material for the space shuttle orbiter. It is used on the wing leading edge and the nose cap, where maximum temperatures are reached on reentry. The existing leading-edge system is a single-plate RCC composite construction with a wall thickness of approximately 1/4 in., making it a prime reliant protection scheme for vehicle operation.

  3. Lead-free piezoceramics

    NASA Astrophysics Data System (ADS)

    Saito, Yasuyoshi; Takao, Hisaaki; Tani, Toshihiko; Nonoyama, Tatsuhiko; Takatori, Kazumasa; Homma, Takahiko; Nagaya, Toshiatsu; Nakamura, Masaya

    2004-11-01

    Lead has recently been expelled from many commercial applications and materials (for example, from solder, glass and pottery glaze) owing to concerns regarding its toxicity. Lead zirconium titanate (PZT) ceramics are high-performance piezoelectric materials, which are widely used in sensors, actuators and other electronic devices; they contain more than 60 weight per cent lead. Although there has been a concerted effort to develop lead-free piezoelectric ceramics, no effective alternative to PZT has yet been found. Here we report a lead-free piezoelectric ceramic with an electric-field-induced strain comparable to typical actuator-grade PZT. We achieved this through the combination of the discovery of a morphotropic phase boundary in an alkaline niobate-based perovskite solid solution, and the development of a processing route leading to highly <001> textured polycrystals. The ceramic exhibits a piezoelectric constant d33 (the induced charge per unit force applied in the same direction) of above 300picocoulombs per newton (pCN-1), and texturing the material leads to a peak d33 of 416pCN-1. The textured material also exhibits temperature-independent field-induced strain characteristics.

  4. Lead-free piezoceramics.

    PubMed

    Saito, Yasuyoshi; Takao, Hisaaki; Tani, Toshihiko; Nonoyama, Tatsuhiko; Takatori, Kazumasa; Homma, Takahiko; Nagaya, Toshiatsu; Nakamura, Masaya

    2004-11-04

    Lead has recently been expelled from many commercial applications and materials (for example, from solder, glass and pottery glaze) owing to concerns regarding its toxicity. Lead zirconium titanate (PZT) ceramics are high-performance piezoelectric materials, which are widely used in sensors, actuators and other electronic devices; they contain more than 60 weight per cent lead. Although there has been a concerted effort to develop lead-free piezoelectric ceramics, no effective alternative to PZT has yet been found. Here we report a lead-free piezoelectric ceramic with an electric-field-induced strain comparable to typical actuator-grade PZT. We achieved this through the combination of the discovery of a morphotropic phase boundary in an alkaline niobate-based perovskite solid solution, and the development of a processing route leading to highly <001> textured polycrystals. The ceramic exhibits a piezoelectric constant d33 (the induced charge per unit force applied in the same direction) of above 300 picocoulombs per newton (pC N(-1)), and texturing the material leads to a peak d33 of 416 pC N(-1). The textured material also exhibits temperature-independent field-induced strain characteristics.

  5. Lead in potatoes

    PubMed Central

    Warren, Harry V.

    1975-01-01

    There are specific environments where potatoes contain much larger amounts of lead than is generally realised. Nevertheless, if we accept the hypothesis that human adults are only likely to be harmed if they absorb more than 100 micrograms of lead daily for extended periods10 then only in rare instances are they apt to be adversely affected by eating potatoes. Medical data suggest that where children are involved the acceptable amounts of lead are significantly less. However, where potatoes do show evidence of contamination by virtue of their high lead content, the possibility of more general contamination should be investigated. The intake of lead from potatoes, if supplemented by lead provided from other foodstuffs, from air, and possibly from water, can well reach unacceptable amounts. Patterson's12 claim that most people in industrialised countries are suffering from a chronic lead insult, does seem justified but, because of the remarkable ability of humans to adapt to some conditions, but how much this insult constitutes a menace to heath must be dealt with by medical men. PMID:1177205

  6. Carbon nanoscrolls by pyrolysis of a polymer

    NASA Astrophysics Data System (ADS)

    Yadav, Prasad; Warule, Sambhaji; Jog, Jyoti; Ogale, Satishchandra

    2012-12-01

    3D network of carbon nanoscrolls was synthesized starting from pyrolysis of poly(acrylic acid-co-maleic acid) sodium salt. It is a catalyst-free process where pyrolysis of polymer leads to formation of carbon form and sodium carbonate. Upon water soaking of pyrolysis product, the carbon form undergoes self-assembly to form carbon nanoscrolls. The interlayer distance between the walls of carbon nanoscroll was found to be 0.34 nm and the carbon nanoscrolls exhibited a surface area of 188 m2/g as measured by the BET method.

  7. Liner protected carbon-carbon heat pipe concept

    NASA Astrophysics Data System (ADS)

    Rovang, Richard D.; Hunt, Maribeth E.

    1992-01-01

    A lightweight, high performance radiator concept using carbon-carbon heat pipes is being developed to support space nuclear power applications, specifically the SP-100 system. Carbon-carbon has been selected as an outer structural tube member because of its high temperature and strength characteristics; however, this material must be protected from the potassium heat pipe working fluid. A metallic liner approach is being taken to provide this fluid barrier. Feasibility issues associated with this approach include materials compatibility, fabricastion of the thin-walled liner, bonding the liner to the carbon-carbon tube, mismatch of coefficient of thermal expansion (CTE), carbon diffusion, and end cap closures. To resolve these issues, a series of test coupons have been fabricated and tested, assessing various liner materials, braze alloys, and substrate precursors. These tests will lead to a final heat pipe architecture, material selection, and component assembly.

  8. Iodide-assisted total lead measurement and determination of different lead fractions in drinking water samples.

    PubMed

    Zhang, Yuanyuan; Ng, Ding-Quan; Lin, Yi-Pin

    2012-07-01

    Lead and its compounds are toxic and can harm human health, especially the intelligence development in children. Accurate measurement of total lead present in drinking water is crucial in determining the extent of lead contamination and human exposure due to drinking water consumption. The USEPA method for total lead measurement (no. 200.8) is often used to analyze lead levels in drinking water. However, in the presence of high concentration of the tetravalent lead corrosion product PbO(2), the USEPA method was not able to fully recover particulate lead due to incomplete dissolution of PbO(2) particles during strong acid digestion. In this study, a new procedure that integrates membrane separation, iodometric PbO(2) measurement, strong acid digestion and ICP-MS measurement was proposed and evaluated for accurate total lead measurement and quantification of different lead fractions including soluble Pb(2+), particulate Pb(II) carbonate and PbO(2) in drinking water samples. The proposed procedure was evaluated using drinking water reconstituted with spiked Pb(2+), spiked particulate Pb(II) carbonate and in situ formed or spiked PbO(2). Recovery tests showed that the proposed procedure and the USEPA method can achieve 93-112% and 86-103% recoveries respectively for samples containing low PbO(2) concentrations (0.018-0.076 mg Pb per L). For samples containing higher concentrations of PbO(2) (0.089-1.316 mg Pb per L), the USEPA method failed to meet the recovery requirement for total lead (85-115%) while the proposed method can achieve satisfactory recoveries (91-111%) and differentiate the soluble Pb(2+), particulate Pb(II) carbonate and PbO(2).

  9. Carbon-carbon piston development

    NASA Technical Reports Server (NTRS)

    Gorton, Mark P.

    1994-01-01

    A new piston concept, made of carbon-carbon refractory-composite material, has been developed that overcomes a number of the shortcomings of aluminum pistons. Carbon-carbon material, developed in the early 1960's, is lighter in weight than aluminum, has higher strength and stiffness than aluminum and maintains these properties at temperatures over 2500 F. In addition, carbon-carbon material has a low coefficient of thermal expansion and excellent resistance to thermal shock. An effort, called the Advanced Carbon-Carbon Piston Program was started in 1986 to develop and test carbon-carbon pistons for use in spark ignition engines. The carbon-carbon pistons were designed to be replacements for existing aluminum pistons, using standard piston pin assemblies and using standard rings. Carbon-carbon pistons can potentially enable engines to be more reliable, more efficient and have greater power output. By utilizing the unique characteristics of carbon-carbon material a piston can: (1) have greater resistance to structural damage caused by overheating, lean air-fuel mixture conditions and detonation; (2) be designed to be lighter than an aluminum piston thus, reducing the reciprocating mass of an engine, and (3) be operated in a higher combustion temperature environment without failure.

  10. A carbon sink pathway increases carbon productivity in cyanobacteria.

    PubMed

    Oliver, John W K; Atsumi, Shota

    2015-05-01

    The burning of fossil reserves, and subsequent release of carbon into the atmosphere is depleting the supply of carbon-based molecules used for synthetic materials including plastics, oils, medicines, and glues. To provide for future society, innovations are needed for the conversion of waste carbon (CO2) into organic carbon useful for materials. Chemical production directly from photosynthesis is a nascent technology, with great promise for capture of CO2 using sunlight. To improve low yields, it has been proposed that photosynthetic capacity can be increased by a relaxation of bottlenecks inherent to growth. The limits of carbon partitioning away from growth within the cell and the effect of partitioning on carbon fixation are not well known. Here we show that expressing genes in a pathway between carbon fixation and pyruvate increases partitioning to 2,3-butanediol (23BD) and leads to a 1.8-fold increase in total carbon yield in the cyanobacterium Synechococcus elongatus PCC 7942. Specific 2,3-butanediol production increases 2.4-fold. As partitioning increases beyond 30%, it leads to a steep decline in total carbon yield. The data suggests a local maximum for carbon partitioning from the Calvin Benson cycle that is scalable with light intensity. Copyright © 2015 International Metabolic Engineering Society. Published by Elsevier Inc. All rights reserved.

  11. Leading Causes of Blindness

    MedlinePlus

    ... Cataract. Photo courtesy of National Eye Institute, NIH Cataracts Cataracts are a clouding of the lenses in your ... older people. More than 22 million Americans have cataracts. They are the leading cause of blindness in ...

  12. Lead Poisoning Prevention Tips

    MedlinePlus

    ... North Dakota Ohio Oklahoma Oregon Pennsylvania Philadelphia Rhode Island South Carolina South Dakota Tennessee Texas Utah Vermont ... up paint debris after work is completed. Create barriers between living/play areas and lead sources. Until ...

  13. Lead and Your Baby

    MedlinePlus

    ... lead, talk to your boss about changing job responsibilities to help keep you and your baby safe ... Participate & Support Make a donation Giving opportunities Our corporate partners In Your Area Tools & Resources Careers Events ...

  14. Surface superconductivity in lead

    SciTech Connect

    Khlyustikov, I. N.

    2016-02-15

    A transition to the surface superconducting state is detected in lead single crystals at a temperature approximately 0.25 mK higher than the bulk superconducting transition temperature. The (H, T) phase diagram of this state is analyzed.

  15. American Lead Action Memorandum

    EPA Pesticide Factsheets

    ACTION MEMORANDUM— Request for a Time-Critical Removal Action andExemption from the $2 Million and 12-Month Statutory Limits at the AmericanLead Site, Indianapolis, Marion County, Indiana (Site ID #B56J)

  16. Feature Leads That Work.

    ERIC Educational Resources Information Center

    Konkle, Bruce E.

    1999-01-01

    Presents advice to scholastic journalists on writing leads for feature stories. Discusses using a summary, a question, a direct quote, a first-person account, alliteration, a shocking statement, contrast, historical reference, descriptions, narratives, metaphors, and similes. (RS)

  17. American Lead Action Memorandum

    EPA Pesticide Factsheets

    ACTION MEMORANDUM— Request for a Time-Critical Removal Action andExemption from the $2 Million and 12-Month Statutory Limits at the AmericanLead Site, Indianapolis, Marion County, Indiana (Site ID #B56J)

  18. Feature Leads That Work.

    ERIC Educational Resources Information Center

    Konkle, Bruce E.

    1999-01-01

    Presents advice to scholastic journalists on writing leads for feature stories. Discusses using a summary, a question, a direct quote, a first-person account, alliteration, a shocking statement, contrast, historical reference, descriptions, narratives, metaphors, and similes. (RS)

  19. Leading Beyond the Future

    DTIC Science & Technology

    2004-05-26

    LEADING BEYOND THE FUTURE A Monograph By Lieutenant Colonel Robert C. Shaw United States Army School of Advanced Military Studies...REPORT DATE 26 MAY 2004 2. REPORT TYPE 3. DATES COVERED - 4. TITLE AND SUBTITLE Leading beyond the future 5a. CONTRACT NUMBER 5b. GRANT...faced these senior leaders. The study shows that the Army must look at many different aspects as it transforms to the Future Force, not just advances in

  20. Lead-210 contamination

    SciTech Connect

    Gray, P.

    1997-12-31

    Nearly all scrap dealers, smelters and other recyclers routinely monitor for radioactivity in shipments entering their facility. These sensitive radiation gate monitors easily detect radium-226 and most other radioactive nuclides. However, the type of detector normally used, sodium iodide scintillation crystals, will not detect the low energy gamma radiation emitted by lead-210 and its progeny. Since lead-210 is a common radioactive contaminant in certain industries, contaminated scrap metal from these industries may avoid detection at the recycler. Lead-210 is a decay product of radon-222 which is produced in small concentrations with natural gas. As the natural gas liquids, particularly ethane and propane, are separated from the natural gas, the radon concentrates in the ethane/propane fraction. The natural gas industry, particularly gas processing facilities and industries using ethane and propane as feed stocks can be significantly contaminated with the radon decay products, especially lead-210, bismuth-210 and polonium-210. Unless the scrap metal is decontaminated before sending to the recycler, the lead-210 contaminated scrap may be processed, resulting in some degree of radioactive contamination of the recycling facilities. Methods of detecting the low energy gamma radiation associated with lead-210 include the pancake G-M detector and the thin crystal-thin window scintillation detector.

  1. Closure device for lead-acid batteries

    DOEpatents

    Ledjeff, Konstantin

    1983-01-01

    A closure device for lead-acid batteries includes a filter of granulated activated carbon treated to be hydrophobic combined with means for preventing explosion of emitted hydrogen and oxygen gas. The explosion prevention means includes a vertical open-end tube within the closure housing for maintaining a liquid level above side wall openings in an adjacent closed end tube. Gases vent from the battery through a nozzle directed inside the closed end tube against an impingement surface to remove acid droplets. The gases then flow through the side wall openings and the liquid level to quench any possible ignition prior to entering the activated carbon filter. A wick in the activated carbon filter conducts condensed liquid back to the closure housing to replenish the liquid level limited by the open-end tube.

  2. Magnesium Diboride Current Leads

    NASA Technical Reports Server (NTRS)

    Panek, John

    2010-01-01

    A recently discovered superconductor, magnesium diboride (MgB2), can be used to fabricate conducting leads used in cryogenic applications. Dis covered to be superconducting in 2001, MgB2 has the advantage of remaining superconducting at higher temperatures than the previously used material, NbTi. The purpose of these leads is to provide 2 A of electricity to motors located in a 1.3 K environment. The providing environment is a relatively warm 17 K. Requirements for these leads are to survive temperature fluctuations in the 5 K and 11 K heat sinks, and not conduct excessive heat into the 1.3 K environment. Test data showed that each lead in the assembly could conduct 5 A at 4 K, which, when scaled to 17 K, still provided more than the required 2 A. The lead assembly consists of 12 steelclad MgB2 wires, a tensioned Kevlar support, a thermal heat sink interface at 4 K, and base plates. The wires are soldered to heavy copper leads at the 17 K end, and to thin copper-clad NbTi leads at the 1.3 K end. The leads were designed, fabricated, and tested at the Forschungszentrum Karlsruhe - Institut foer Technische Physik before inclusion in Goddard's XRS (X-Ray Spectrometer) instrument onboard the Astro-E2 spacecraft. A key factor is that MgB2 remains superconducting up to 30 K, which means that it does not introduce joule heating as a resistive wire would. Because the required temperature ranges are 1.3-17 K, this provides a large margin of safety. Previous designs lost superconductivity at around 8 K. The disadvantage to MgB2 is that it is a brittle ceramic, and making thin wires from it is challenging. The solution was to encase the leads in thin steel tubes for strength. Previous designs were so brittle as to risk instrument survival. MgB2 leads can be used in any cryogenic application where small currents need to be conducted at below 30 K. Because previous designs would superconduct only at up to 8 K, this new design would be ideal for the 8-30 K range.

  3. Lightweight, durable lead-acid batteries

    DOEpatents

    Lara-Curzio, Edgar; An, Ke; Kiggans, Jr., James O; Dudney, Nancy J; Contescu, Cristian I; Baker, Frederick S; Armstrong, Beth L

    2013-05-21

    A lightweight, durable lead-acid battery is disclosed. Alternative electrode materials and configurations are used to reduce weight, to increase material utilization and to extend service life. The electrode can include a current collector having a buffer layer in contact with the current collector and an electrochemically active material in contact with the buffer layer. In one form, the buffer layer includes a carbide, and the current collector includes carbon fibers having the buffer layer. The buffer layer can include a carbide and/or a noble metal selected from of gold, silver, tantalum, platinum, palladium and rhodium. When the electrode is to be used in a lead-acid battery, the electrochemically active material is selected from metallic lead (for a negative electrode) or lead peroxide (for a positive electrode).

  4. Lightweight, durable lead-acid batteries

    DOEpatents

    Lara-Curzio, Edgar [Lenoir City, TN; An, Ke [Knoxville, TX; Kiggans, Jr., James O.; Dudney, Nancy J [Knoxville, TN; Contescu, Cristian I [Knoxville, TN; Baker, Frederick S [Oak Ridge, TN; Armstrong, Beth L [Clinton, TN

    2011-09-13

    A lightweight, durable lead-acid battery is disclosed. Alternative electrode materials and configurations are used to reduce weight, to increase material utilization and to extend service life. The electrode can include a current collector having a buffer layer in contact with the current collector and an electrochemically active material in contact with the buffer layer. In one form, the buffer layer includes a carbide, and the current collector includes carbon fibers having the buffer layer. The buffer layer can include a carbide and/or a noble metal selected from of gold, silver, tantalum, platinum, palladium and rhodium. When the electrode is to be used in a lead-acid battery, the electrochemically active material is selected from metallic lead (for a negative electrode) or lead peroxide (for a positive electrode).

  5. Carbon monoxide intoxication

    SciTech Connect

    Kales, S.N. )

    1993-11-01

    Carbon monoxide poisoning usually results from inhalation of exhaust fumes from motor vehicles, smoke from fires or fumes from faulty heating systems. Carbon monoxide has a high affinity for hemoglobin, with which it forms carboxyhemoglobin. The resulting decrease in both oxygen-carrying capacity and oxygen release can lead to end-organ hypoxia. The clinical presentation is nonspecific. Headache, dizziness, fatigue and nausea are common in mild to moderate carbon monoxide poisoning. In more severe cases, tachycardia, tachypnea and central nervous system depression occur. When carbon monoxide intoxication is suspected, empiric treatment with 100 percent oxygen should be initiated immediately. The diagnosis is confirmed by documenting an elevated carboxyhemoglobin level. Hyperbaric oxygen therapy is recommended in patients with neurologic dysfunction, cardiac dysfunction or a history of unconsciousness. 26 refs.

  6. Hemotoxicity of carbon nanotubes.

    PubMed

    Bussy, Cyrill; Methven, Laura; Kostarelos, Kostas

    2013-12-01

    Carbon nanotubes may enter into the bloodstream and interact with blood components indirectly via translocation following unintended exposure or directly after an intended administration for biomedical purposes. Once introduced into systemic circulation, nanotubes will encounter various proteins, biomolecules or cells which have specific roles in the homeostasis of the circulatory system. It is therefore essential to determine whether those interactions will lead to adverse effects or not. Advances in the understanding of how carbon nanotubes interact with blood proteins, the complement system, red blood cells and the hemostatic system are reviewed in this article. While many studies on carbon nanotube health risk assessment and their biomedical applications have appeared in the last few years, reports on the hemocompatibility of these nanomaterials remain surprisingly limited. Yet, defining the hemotoxicological profile is a mandatory step toward the development of clinically-relevant medications or contrast agents based on carbon nanotubes.

  7. Technical Status and Progress of Lead Recycling of Battery

    NASA Astrophysics Data System (ADS)

    Li, Wei-feng; Jiang, Li-hua; Zhan, Jing; Zhang, Chuan-fu

    The characteristics of various components in waste lead acid battery are analyzed in this paper. The present status and the study progress situation in industry production and research field of recycling of waste lead acid battery and lead paste used broken-separation technology are introduced. The comparison of advantages and disadvantages in different industry processes is carried. The advantages of redox bath smelting of lead concentrate and lead paste are analyzed. The method of redox bath smelting will be a low-carbon, environmentally friendly and efficient processes of secondary lead production and can be intensive to desulfurize for high temperature pool.

  8. Understanding corrosion control strategies for lead

    SciTech Connect

    Schock, M.R

    1989-07-01

    This article reviews the factors that should be considered by individual utilities in developing a lead-solubility control program based on the adjustment of pH, dissolved inorganic carbonate, and orthophosphate. A flow chart is provided to aid in the selection of the best treatment scheme; it is based on the philosophy that chemical models are a useful qualitative guide to the impact of water chemistry on lead solubility but that levels of adjustment should be determined by feedback from pilot testing.

  9. EXPERIMENTS WITH A RESIN-IN-PULP PROCESS FOR TREATING LEAD-CONTAMINATED SOIL

    EPA Science Inventory

    This paper presents the results of experiments to evaluate the potential for using a resin-in-pulp process to remove lead contamination from soil. These experiments examined the kinetics and equilibrium partitioning of lead, lead carbonate, lead oxide, and lead sulfate in resin-s...

  10. EXPERIMENTS WITH A RESIN-IN-PULP PROCESS FOR TREATING LEAD-CONTAMINATED SOIL

    EPA Science Inventory

    This paper presents the results of experiments to evaluate the potential for using a resin-in-pulp process to remove lead contamination from soil. These experiments examined the kinetics and equilibrium partitioning of lead, lead carbonate, lead oxide, and lead sulfate in resin-s...

  11. Food Exposures to Lead

    PubMed Central

    Kolbye, Albert C.; Mahaffey, Kathryn R.; Fiorino, John A.; Corneliussen, Paul C.; Jelinek, Charles F.

    1974-01-01

    Exposures to lead have emanated from various sources, including food, throughout human history. Occupational and environmental exposures (especially pica) appear to account for much of the identified human disease, however, food-borne exposures deserve further investigation. Lead residues in food can result from: biological uptake from soils into plants consumed by food animals or man, usage of lead arsenate pesticides, inadvertent addition during food processing, and by leaching them improperly glazed pottery used as food storage or dining utensils. Estimates of total dietary exposure should reflect frequency distribution data on lead levels in specific food commodities in relation to the quantities actually ingested by various sample populations to distinguish degrees of risk associated with particular dietary habits. Earlier estimates of average total dietary intake of lead by adults have been reported to range from above 500 μg/day downward with more recent estimates suggesting averages of 200 μg/day or lower. The strengths and weaknesses of these data are discussed along with analytical and sampling considerations. FDA programs related to food surveillance, epidemiology, and toxicological investigation are briefly described. PMID:4406646

  12. Analysis of the sources and dynamic processes leading to the increase of atmospheric CO2, black carbon and other trace species during recent urban pollution events in the Paris megacity region : a synergy of resources provided by the IPSL OCAPI platform.

    NASA Astrophysics Data System (ADS)

    Xueref-Remy, I.; Foret, G.; Beekmann, M.; Brégonzio-Rozier, L.; Favez, O.; Gros, V.; Moreau-Guigon, E.; Vogel, F. R.; Belviso, S.; Ghersi, V.; Dupont, J. C.; Bodichon, R.; Cailteau-Fischbach, C.; Baisnee, D.; Peinado, F.; Haeffelin, M.; DeCola, P.; Turnbull, J. C.; Chelin, P.; Te, Y. V.; Formenti, P.; Doussin, J. F.; Gratien, A.; Desboeufs, K. V.; Ramage, K.; Jeseck, P.; Delmotte, M.; Ramonet, M.; Michoud, V.; Ravetta, F.

    2016-12-01

    Nowadays, more than 50% of the global population leave in urban centers which activities generate large anthropogenic emissions of CO2 (more than 70% of fossil fuel CO2 comes from urbanized/industrialized areas) and reactive gases that endanger our climate, the health of human beings and surrounding ecosystems. The worst situations are encountered during urban pollution events that usually form under anticyclonic conditions. Analyzing the contribution of the local and regional sources of urban CO2 and co-emitted species vs the remote ones, as well as the nature of these sources and the dynamical processes that lead to the building of such events can provide interesting knowledge for helping urban policy makers to better identify the role of anthropogenic/biogenic sources on the urban air composition and to take proper decisions in matter of CO2 and pollutants sources mitigation. With 12 million of people, Paris (France) is the second megacity in Europe. In 2016, two pollution events occured in the Paris region during which the instrumental platform OCAPI (http://observations.ipsl.fr/composition-atmospherique-en-idf.html) from IPSL (Institut Pierre Simon Laplace) was mobilized in collaboration with air quality governing actors (AIRPARIF, INERIS) to collect a bunch of observations. Five sites located in the urban, peri-urban and rural areas of Paris were equiped with in-situ analyzers (CO2, CO, black carbon, 13CO2, COS) ; Fourier transform spectrometers for column measurements (XCO2, XCO, XCOS), particle filters (for aerosols size and content analysis) ; air samples (levoglucosan, 14CO2, VOCs) ; and Lidar profilers (boundary layer height ; wind profiles). These data, combined with a backtrajectories analysis, give information about the dynamical processes that lead to the formation of the pollution events and on the contribution of local, regional and remote sources. The analysis of the correlations between the trace species and of the isotopic content of carbon in

  13. Lead zirconate titanate ceramics

    SciTech Connect

    Walker, B.E. Jr.

    1986-12-02

    This patent describes a lead zirconate titanate (PZT) piezoelectric ceramic composition which, based on total composition weight, consists essentially of a solid solution of lead zirconate and lead titanate in a PbZrO/sub 3/:PbTiO/sub 3/ ratio from about 0.505:0.495 to about 0.54:0.46; a halide salt selected from the group consisting of fluorides and chlorides of alkali metal and alkaline earth elements and mixtures thereof except for francium and radium in an amount from about 0.5 to 2 weight percent; and an oxide selected from the group consisting of magnesium, barium, scandium, aluminum, lanthanum, praesodynium, neodymium, samarium, and mixtures thereof in an amount from about 0.5 to about 6 weight percent, the relative amount of oxide being from about 1 to about 4 times that of the halide.

  14. Pacemaker lead endocarditis

    PubMed Central

    Scheffer, M.; van der Linden, E.; van Mechelen, R.

    2003-01-01

    We present a patient with a pacemaker lead endocarditis who showed no signs of pocket infection but with high fever and signs of infection in the routine laboratory tests. A diagnosis of pacemaker lead endocarditis must be considered in all patients with fever and infection parameters who have a pacemaker inserted, not only in the first weeks after implantation but also late after implantation, as long as no other cause of infection has been found. Transthoracal echocardiography alone is not sensitive enough to establish the correct diagnosis. Transoesophageal echocardiography (TEE) is mandatory to demonstrate the presence or absence of a vegetation on a pacemaker lead. ImagesFigure 1Figure 2Figure 3Figure 4 PMID:25696204

  15. Placental Permeability of Lead

    PubMed Central

    Carpenter, Stanley J.

    1974-01-01

    The detection of lead in fetal tissues by chemical analysis has long been accepted as prima facie evidence for the permeability of the placenta to this nonessential trace metal. However, only a few investigations, all on lower mammalian species, have contributed any direct experimental data bearing on this physiological process. Recent radioactive tracer and radioautographic studies on rodents have shown that lead crosses the placental membranes rapidly and in significant amounts even at relatively low maternal blood levels. While it is not possible to extrapolate directly the results of these experiments to humans because of differences in placental structure and other factors, the results do serve as a warning of the possible hazard to the human embryo and fetus of even low levels of lead in the maternal system. PMID:4857497

  16. Calcium Carbonate

    MedlinePlus

    Calcium carbonate is a dietary supplement used when the amount of calcium taken in the diet is not ... for healthy bones, muscles, nervous system, and heart. Calcium carbonate also is used as an antacid to relieve ...

  17. Environmental lead in Mexico.

    PubMed

    Albert, L A; Badillo, F

    1991-01-01

    From the data presented here, it can be concluded that environmental exposure to lead is a particularly severe problem in Mexico. As has been shown, there are very important sources of exposure to this metal: (a) for rural populations who manufacture and/or utilize lead-glazed pottery, (b) for urban populations who are exposed to high air lead concentrations due to the continued use of lead fuel additives, (c) for workers of several industries, mainly those of batteries and pigments, (d) for consumers who routinely eat canned foods such as hot peppers and fruit products, and (e) for the general population living in the vicinity of smelters, refineries and other industries that emit lead. Therefore, in Mexico only those native populations living in very primitive communities, far away from all civilized life, could be expected to be free from this exposure. At the same time, and despite the relatively few data available, it can be stated that the exposure to lead of populations in Mexico could be approaching levels that might be highly hazardous, in particular for the neuropsychological health of children. Regarding the presence of lead in the environment, despite the fact that the available studies are not enough, it is evident that pollution by this metal is widespread and that there is a serious lack of studies for most regions of the country, including several that might be expected to be highly polluted. At the same time, it is evident that the official attention paid to the problem, either in regulations, support of further studies, or implementation of effective control measures has been far from the level needed according to the available data. Lead in gasoline is still used at very high concentrations in all the country, with the exception of Mexico City and its surrounding area, while no studies have been carried out to determine the potential health and environmental impact of this practice in regions outside Mexico City. Despite the fact that the Torre

  18. Thrombus on pacemaker lead.

    PubMed

    Raut, Monish S; Maheshwari, Arun; Dubey, Sumir

    2015-12-01

    A 58-year-old male was admitted with history of shortness of breath and recurrent fever since two months. He had undergone permanent pacemaker implantation six years back for complete heart block. The patient was persistently having thrombocytopenia. Echocardiographic examination revealed mass (size 4.28 cm(2)) attached to pacemaker lead in right atrium. The patient was scheduled for open-heart surgery for removal of right atrial mass. During surgery, pacemaker leads and pulse generator were also removed along with mass considering the possible source of infection.

  19. A Strategy for Leading

    DTIC Science & Technology

    1988-04-01

    34p I Z" AIR COMMAND AND STAFF COLLEGE STUDENT REPORT , A Strategy for Leading / or Annabelle D. Solis 88-2460 "insights into tomorrow" AA AA DTOK...with any reproduced or adapted portions of this document. REPORT NUMBER 88-2460 TITLE A STRATEGY FOR LEADING AUTHOR(S) MAJOR ANNABELLE D. SOLIS, USAF...Special -*-, *l I - I* A l _... .... ._ .. . ...V - .op A * e&ZA ABOUT THE AUTHOR Major Annabelle (Tina) D. Solis graduated from the University of South

  20. Carbonized asphaltene-based carbon-carbon fiber composites

    DOEpatents

    Bohnert, George; Lula, James; Bowen, III, Daniel E.

    2016-12-27

    A method of making a carbon binder-reinforced carbon fiber composite is provided using carbonized asphaltenes as the carbon binder. Combinations of carbon fiber and asphaltenes are also provided, along with the resulting composites and articles of manufacture.

  1. Adsorption over polyacrylonitrile based carbon monoliths

    NASA Astrophysics Data System (ADS)

    Nandi, Mahasweta; Dutta, Arghya; Patra, Astam Kumar; Bhaumik, Asim; Uyama, Hiroshi

    2013-02-01

    Highly porous activated carbon monoliths have been prepared from mesoporous polyacrylonitrile (PAN) monolith as the carbon precursor. The mesoporous PAN monoliths are fabricated by a unique and facile template-free method which on carbonization gives N-doped activated carbon monoliths. The carbonization is achieved via two step thermal process which includes pretreatment in air leading to cyclization and subsequent aromatization of the PAN moieties followed by carbonization in a mixture of argon and carbon dioxide to give a layered carbon framework. Nitrogen sorption experiments carried over these carbon monoliths revealed high surface area (ca. 2500 m2g-1) for these materials with precise micropore size distribution. The activated carbons show extraordinarily high CO2 capture capacity and the uptake up to 3 bar has been found to be as high as 22.5 and 10.6 mmol/g at 273 K and 298 K, respectively.

  2. Electrochemical battery employing a latex bonded lead dioxide electrode

    SciTech Connect

    Bergum, B.; Bredland, A.; Paulson, J.

    1980-07-29

    An improvement in an electrochemical primary battery of the reserve type comprising an anode, an electrolyte, a separator, and a cathode, containing a lead dioxide material wherein the improvement is the material being comprised of a mixture of lead dioxide, carbon black, and butyl rubber latex.

  3. Lead Poisoning in Children.

    ERIC Educational Resources Information Center

    Lin-Fu, Jane S.

    Designed as a public information pamphlet, the text discusses the problem of lead poisoning in children. The preventable nature of the problem is stressed as well as needed action on the part of the public, physicians and other health workers, and the legislators. The pamphlet emphasizes that each of these areas is essential in preventing death or…

  4. Girls Leading Outward

    ERIC Educational Resources Information Center

    Hamed, Heather; Reyes, Jazmin; Moceri, Dominic C.; Morana, Laura; Elias, Maurice J.

    2011-01-01

    The authors describe a program implemented in Red Bank Middle School in New Jersey to help at-risk, minority middle school girls realize their leadership potential. The GLO (Girls Leading Outward) program was developed by the Developing Safe and Civil Schools Project at Rutgers University and is facilitated by university students. Selected middle…

  5. Lead and compounds (inorganic)

    Integrated Risk Information System (IRIS)

    Lead and compounds ( inorganic ) ; CASRN 7439 - 92 - 1 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for

  6. ALL AGES LEAD MODEL

    EPA Science Inventory

    The Integrated Exposure Uptake Biokinetic (IEUBK) Model for Lead in Children (version 0.99d) was released in March 1994, and has been widely accepted in the risk assessment community as a tool for implementing the site specific risk assessment process when the issue is childhood...

  7. Machining lead wafers

    SciTech Connect

    Schamaun, R.T.

    1987-09-01

    Recently, MEC-6 machined some 4-inch-diameter lead wafers to precision tolerances. The tolerance on the wafer thickness was +-0.000080 inch. A diamond tool was used to machine the wafers on a Moore No. 3 lathe. This report discusses the methods used to machine the wafers, the fixtures used to hold the wafers, and the inspection methods and results.

  8. Lead Thickness Measurements

    SciTech Connect

    Rucinski, R.; /Fermilab

    1998-02-16

    The preshower lead thickness applied to the outside of D-Zero's superconducting solenoid vacuum shell was measured at the time of application. This engineering documents those thickness measurements. The lead was ordered in sheets 0.09375-inch and 0.0625-inch thick. The tolerance on thickness was specified to be +/- 0.003-inch. The sheets all were within that thickness tolerance. The nomenclature for each sheet was designated 1T, 1B, 2T, 2B where the numeral designates it's location in the wrap and 'T' or 'B' is short for 'top' or 'bottom' half of the solenoid. Micrometer measurements were taken at six locations around the perimeter of each sheet. The width,length, and weight of each piece was then measured. Using an assumed pure lead density of 0.40974 lb/in{sup 3}, an average sheet thickness was calculated and compared to the perimeter thickness measurements. In every case, the calculated average thickness was a few mils thinner than the perimeter measurements. The ratio was constant, 0.98. This discrepancy is likely due to the assumed pure lead density. It is not felt that the perimeter is thicker than the center regions. The data suggests that the physical thickness of the sheets is uniform to +/- 0.0015-inch.

  9. Change, Lead, Succeed

    ERIC Educational Resources Information Center

    Munger, Linda; von Frank, Valerie

    2010-01-01

    Redefine leadership in your school, and create capacity through school leadership teams that successfully coordinate professional learning. "Change, Lead, Succeed" shows school leaders and teachers in leadership roles what they need to know to effectively create a culture for change. Find out what distinguishes a school leadership team from other…

  10. Women who lead.

    PubMed

    Silver, A L

    1996-03-01

    This essay reviews aspects of historical and cultural changes that now permit women increasing opportunities to lead both women and men. Women assuming leadership responsibilities undergo psychic reorganization, reworking their personal histories and their modes of interaction. The author challenges women who inhibit their leadership potential to scrutinize their attitudes and to consider the implications for the next generation of women.

  11. Change, Lead, Succeed

    ERIC Educational Resources Information Center

    Munger, Linda; von Frank, Valerie

    2010-01-01

    Redefine leadership in your school, and create capacity through school leadership teams that successfully coordinate professional learning. "Change, Lead, Succeed" shows school leaders and teachers in leadership roles what they need to know to effectively create a culture for change. Find out what distinguishes a school leadership team from other…

  12. Biomedical ground lead system

    NASA Technical Reports Server (NTRS)

    1972-01-01

    The design and verification tests for the biomedical ground lead system of Apollo biomedical monitors are presented. Major efforts were made to provide a low impedance path to ground, reduce noise and artifact of ECG signals, and limit the current flowing in the ground electrode of the system.

  13. Beam lead forming tool

    NASA Technical Reports Server (NTRS)

    Clemons, P. W.

    1973-01-01

    Tool was designed for table-top manual operation that can bend leads to any desired angle up to 90 degrees. It can be readily adapted to electrical, hydraulic, or pneumatic operation. This innovation may be of interest to electronics, sheet metal, and appliance industries.

  14. Girls Leading Outward

    ERIC Educational Resources Information Center

    Hamed, Heather; Reyes, Jazmin; Moceri, Dominic C.; Morana, Laura; Elias, Maurice J.

    2011-01-01

    The authors describe a program implemented in Red Bank Middle School in New Jersey to help at-risk, minority middle school girls realize their leadership potential. The GLO (Girls Leading Outward) program was developed by the Developing Safe and Civil Schools Project at Rutgers University and is facilitated by university students. Selected middle…

  15. Leading by example.

    PubMed

    Black, Steven

    2004-11-01

    There is a new face leading nursing and midwifery in Scotland: chief nursing officer (CNO) Paul Martin. As successor to Annie Jarvie, who retired in September after 12 years in post, he wants the profession's leaders to ensure that nurses and midwives remain at the heart of NHS modernisation.

  16. Leading by Learning

    ERIC Educational Resources Information Center

    Brookhart, Susan M.; Moss, Connie M.

    2013-01-01

    A lot has changed in the principalship since the principal was the head teacher in a school. Current principals are building administrators and that is likely to continue, the authors posit. Nonetheless, they report their study focusing on leadership's role in formative assessment concluded that in order to lead learning the principal must become…

  17. ALL AGES LEAD MODEL

    EPA Science Inventory

    The Integrated Exposure Uptake Biokinetic (IEUBK) Model for Lead in Children (version 0.99d) was released in March 1994, and has been widely accepted in the risk assessment community as a tool for implementing the site specific risk assessment process when the issue is childhood...

  18. Lead poisoning: The invisible disease

    USGS Publications Warehouse

    Friend, Milton

    1989-01-01

    Lead poisoning is an intoxication resulting from absorption of hazardous levels of lead into body tissues. Lead pellets from shot shells, when ingested, are the most common source of lead poisoning in migratory birds. Other far less common sources include lead fishing sinkers, mine wastes, paint pigments, bullets, and other lead objects that are swallowed.

  19. LEAD SEVERING CONTRIVANCE

    DOEpatents

    Widmaier, W.

    1958-04-01

    A means for breaking an electrical circuit within an electronic tube during the process of manufacture is described. Frequently such circuits must be employed for gettering or vapor coating purposes, however, since an external pair of corector pins having no use after manufacture, is undesirable, this invention permits the use of existing leads to form a temporary circuit during manufacture, and severing it thereafter. One portion of the temporary circuit, made from a springy material such as tungsten, is spot welded to a fusable member. To cut the circuit an external radiant heat source melts the fusable member, allowing the tensed tungsten spring to contract and break the circuit. This inexpensive arrangement is particularly useful when the tube has a great many external leads crowded into the tube base.

  20. Lead iodide nuclear spectrometers

    SciTech Connect

    Lund, J.C.; Shah, K.S.; Squillante, M.R.; Sinclair, F.

    1988-02-01

    This paper discusses the preparation of radiation detectors from the semiconductor lead iodide, PbI/sub 2/, and evaluates the performance of these devices as x-ray and gamma ray spectrometers. It was found that lead iodide detectors prepared from melt grown crystals exhibited good energy resolution for low energy (<10 keV) x-rays. The energy resolution for higher energy photons was less, consistent with the measured values of the electron and hole mobility-lifetime products. The performance of the PbI/sub 2/ detectors at elevated temperatures was also measured and it was found that the detectors continued to operate well at temperatures over 100/sup 0/C.

  1. Lead/acid batteries

    NASA Astrophysics Data System (ADS)

    Bullock, Kathryn R.

    Lead/acid batteries are produced in sizes from less than 1 to 3000 Ah for a wide variety of portable, industrial and automotive applications. Designs include Planté, Fauré or pasted, and tubular electrodes. In addition to the traditional designs which are flooded with sulfuric acid, newer 'valve-regulated" designs have the acid immolibized in a silica gel or absorbed in a porous glass separator. Development is ongoing worldwide to increase the specific power, energy and deep discharge cycle life of this commercially successful system to meet the needs of new applications such as electric vehicles, load leveling, and solar energy storage. The operating principles, current status, technical challenges and commercial impact of the lead/acid battery are reviewed.

  2. Functionalized Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Lebron, Marisabel; Mintz, Eric; Meador, Michael A.; Hull, David R.; Scheiman, Daniel A.; Willis, Peter; Smalley, Richard E.

    2001-01-01

    Carbon nanotubes have created a great deal of excitement in the Materials Science community because of their outstanding mechanical, electrical, and thermal properties. Use of carbon nanotubes as reinforcements for polymers could lead to a new class of composite materials with properties, durability, and performance far exceeding that of conventional fiber reinforced composites. Organized arrays of carbon nanotubes, e.g., nanotube monolayers, could find applications as thermal management materials, light emitting devices, and sensor arrays. Carbon nanotubes could also be used as templates upon which nanotubes from other materials could be constructed. Successful use of carbon nanotubes in any of these potential applications requires the ability to control the interactions of nanotubes with each other and with other materials, e.g., a polymer matrix. One approach to achieving this control is to attach certain chemical groups to the ends and/or side-walls of the nanotubes. The nature of these chemical groups can be varied to achieve the desired result, such as better adhesion between the nanotubes and a polymer. Under a joint program between NASA Glenn, Clark Atlanta University, and Rice University researchers are working on developing a chemistry "tool-kit" that will enable the functionalization of carbon nanotubes with a variety of chemical groups. Recent results of this effort will be discussed.

  3. Carbon dioxide poisoning.

    PubMed

    Langford, Nigel J

    2005-01-01

    Carbon dioxide is a physiologically important gas, produced by the body as a result of cellular metabolism. It is widely used in the food industry in the carbonation of beverages, in fire extinguishers as an 'inerting' agent and in the chemical industry. Its main mode of action is as an asphyxiant, although it also exerts toxic effects at cellular level. At low concentrations, gaseous carbon dioxide appears to have little toxicological effect. At higher concentrations it leads to an increased respiratory rate, tachycardia, cardiac arrhythmias and impaired consciousness. Concentrations >10% may cause convulsions, coma and death. Solid carbon dioxide may cause burns following direct contact. If it is warmed rapidly, large amounts of carbon dioxide are generated, which can be dangerous, particularly within confined areas. The management of carbon dioxide poisoning requires the immediate removal of the casualty from the toxic environment, the administration of oxygen and appropriate supportive care. In severe cases, assisted ventilation may be required. Dry ice burns are treated similarly to other cryogenic burns, requiring thawing of the tissue and suitable analgesia. Healing may be delayed and surgical intervention may be required in severe cases.

  4. Oxidation of Carbon/Carbon through Coating Cracks

    NASA Technical Reports Server (NTRS)

    Jacobson, N. S.; Roth, d. J.; Rauser, R. W.; Cawley, J. D.; Curry, D. M.

    2008-01-01

    Reinforced carbon/carbon (RCC) is used to protect the wing leading edge and nose cap of the Space Shuttle Orbiter on re-entry. It is composed of a lay-up of carbon/carbon fabric protected by a SiC conversion coating. Due to the thermal expansion mismatch of the carbon/carbon and the SiC, the SiC cracks on cool-down from the processing temperature. The cracks act as pathways for oxidation of the carbon/carbon. A model for the diffusion controlled oxidation of carbon/carbon through machined slots and cracks is developed and compared to laboratory experiments. A symmetric cylindrical oxidation cavity develops under the slots, confirming diffusion control. Comparison of cross sectional dimensions as a function of oxidation time shows good agreement with the model. A second set of oxidation experiments was done with samples with only the natural craze cracks, using weight loss as an index of oxidation. The agreement of these rates with the model is quite reasonab

  5. Contacts for organic switches with carbon-nanotube leads.

    PubMed

    Wierzbowska, Małgorzata; Rode, Michał F; Sadek, Mikołaj; Sobolewski, Andrzej L

    2015-06-19

    We focus on two classes of organic switches operating due to the photo- or field-induced proton transfer (PT) process. By means of first-principles simulations, we search for the atomic contacts that strengthen diversity of the two swapped current-voltage (I-V) characteristics between two tautomers. We emphasize that the low-resistive contacts do not necessarily possess good switching properties. Very often, the higher-current flow makes it more difficult to distinguish between the logic states. Instead, the more resistive contacts multiply a current gear to a larger extent. The low- and high-bias work regimes set additional conditions, which are fulfilled by different contacts: (i) in the very low-voltage regime, the direct connections to the nanotubes perform better than the popular sulfur contacts, and (ii) in the higher-voltage regime, the best are the peroxide (-O-O-) contacts. Additionally, we find that the switching-bias value is not an inherent property of the conducting molecule, but it strongly depends on the chosen contacts.

  6. Carbon-Carbon Piston Architectures

    NASA Technical Reports Server (NTRS)

    Rivers, H. Kevin (Inventor); Ransone, Philip O. (Inventor); Northam, G. Burton (Inventor); Schwind, Francis A. (Inventor)

    1999-01-01

    An improved structure for carbon-carbon composite piston architectures consists of replacing the knitted fiber, three-dimensional piston preform architecture described in U.S. Pat. No. 4.909,133 (Taylor et al.) with a two-dimensional lay-up or molding of carbon fiber fabric or tape. Initially. the carbon fabric or tape layers are prepregged with carbonaceous organic resins and/or pitches and are laid up or molded about a mandrel. to form a carbon-fiber reinforced organic-matrix composite part shaped like a "U" channel, a "T"-bar. or a combination of the two. The molded carbon-fiber reinforced organic-matrix composite part is then pyrolized in an inert atmosphere, to convert the organic matrix materials to carbon. At this point, cylindrical piston blanks are cored from the "U" channel, "T"-bar, or combination part. These blanks are then densified by reimpregnation with resins or pitches which are subsequently carbonized. Densification is also be accomplished by direct infiltration with carbon by vapor deposition processes. Once the desired density has been achieved, the piston billets are machined to final piston dimensions; coated with oxidation sealants; and/or coated with a catalyst. When compared to conventional steel or aluminum-alloy pistons, the use of carbon-carbon composite pistons reduces the overall weight of the engine; allows for operation at higher temperatures without a loss of strength; allows for quieter operation; reduces the heat loss; and reduces the level of hydrocarbon emissions.

  7. Zinc and lead deposits of northern Arkansas

    USGS Publications Warehouse

    McKnight, Edwin T.

    1935-01-01

    Zinc and lead ores occur in the northern counties of Arkansas, from the Arkansas-Oklahoma line on the west to the Coastal Plain, in Lawrence County, on the east, but are concentrated chiefly in Marion, Boone, Newton, Searcy, Sharp, and Lawrence Counties.  Lead ore was reported in the region as early as 1818, and small reduction plants were built in the vicinity of Lead Hill in 1851 or 1852.  The Confederate forces obtained lead from northern Arkansas during the Civil War.  Zinc mining began at a somewhat later date and reached its peak between 1914 and 1917, but since that time mining has been at a low ebb.  The later history of lead mining in the region has closely paralleled that of zinc.  The production from the region since 1907, according to statistics compiled by the United States Geological Survey, has been, in round numbers, 1,900 tons of lead sulphide concentrates, 11,5000 tons of zinc sulphide concentrates, and 51,3000 tons of zinc carbonate and silicate concentrates.

  8. Reconciling biodiversity and carbon conservation.

    PubMed

    Thomas, Chris D; Anderson, Barbara J; Moilanen, Atte; Eigenbrod, Felix; Heinemeyer, Andreas; Quaife, Tristan; Roy, David B; Gillings, Simon; Armsworth, Paul R; Gaston, Kevin J

    2013-05-01

    Climate change is leading to the development of land-based mitigation and adaptation strategies that are likely to have substantial impacts on global biodiversity. Of these, approaches to maintain carbon within existing natural ecosystems could have particularly large benefits for biodiversity. However, the geographical distributions of terrestrial carbon stocks and biodiversity differ. Using conservation planning analyses for the New World and Britain, we conclude that a carbon-only strategy would not be effective at conserving biodiversity, as have previous studies. Nonetheless, we find that a combined carbon-biodiversity strategy could simultaneously protect 90% of carbon stocks (relative to a carbon-only conservation strategy) and > 90% of the biodiversity (relative to a biodiversity-only strategy) in both regions. This combined approach encapsulates the principle of complementarity, whereby locations that contain different sets of species are prioritised, and hence disproportionately safeguard localised species that are not protected effectively by carbon-only strategies. It is efficient because localised species are concentrated into small parts of the terrestrial land surface, whereas carbon is somewhat more evenly distributed; and carbon stocks protected in one location are equivalent to those protected elsewhere. Efficient compromises can only be achieved when biodiversity and carbon are incorporated together within a spatial planning process.

  9. Leading teams that thrive.

    PubMed

    Karre, Idahlynn

    2012-12-01

    The purpose of this review is to explore pathways and develop specific knowledge and skills for leading teams that thrive. Here we will discuss current research findings and specific strategies you can use to create stronger more engaged work teams. Recent research findings in leadership from the Gallup Organization and Vital Smarts provide the framework for this discussion. When team members have clear expectations and role clarity, are engaged in conversations that matter, and have knowledge and skill to participate mindfully in crucial conversations, teams thrive.

  10. Lead Speciation in Microorganisms.

    PubMed

    Stewart, Theodora J

    2017-04-10

    The biogeochemical cycles of lead (Pb) have been largely affected by anthropogenic activities as a result of its high natural abundance and use over the centuries [1]. At sites more strongly impacted by urbanization [2] and mining [3], Pb is found at high nano to low micromolar concentrations in surface waters, and can be significantly higher in soil and sediment [4]. Microorganisms are found everywhere and their responses to Pb exposure can range from resistant to highly sensitive [5, 6]. These varying levels of toxicity can be attributed to the cellular handling of Pb, making it important to understand the role of intracellular Pb speciation for more accurate toxicity predictions.

  11. Leading Strategic Leader Teams

    DTIC Science & Technology

    2008-03-25

    SUBTITLE Leading Strategic Leader Teams 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR( S ) Willard Burleson 5d...PROJECT NUMBER 5e. TASK NUMBER 5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME( S ) AND ADDRESS(ES) U.S. Army War College ,122 Forbes Ave.,Carlisle...PA,17013-5220 8. PERFORMING ORGANIZATION REPORT NUMBER 9. SPONSORING/MONITORING AGENCY NAME( S ) AND ADDRESS(ES) 10. SPONSOR/MONITOR’S ACRONYM( S ) 11

  12. Leading change: 2--planning.

    PubMed

    Kerridge, Joanna

    National initiatives have outlined the importance of involving frontline staff in service improvement, and the ability to influence and manage change has been identified as an essential skill for delivering new models of care. Nurses often have to take the lead in managing change in clinical practice. The second in a three-part series is designed to help nurses at all levels develop the knowledge and skills to function as change agents within their organisations. This article focuses on planning the change and dealing with resistance.

  13. Carbonate aquifers

    USGS Publications Warehouse

    Cunningham, Kevin J.; Sukop, Michael; Curran, H. Allen

    2012-01-01

    Only limited hydrogeological research has been conducted using ichnology in carbonate aquifer characterization. Regardless, important applications of ichnology to carbonate aquifer characterization include its use to distinguish and delineate depositional cycles, correlate mappable biogenically altered surfaces, identify zones of preferential groundwater flow and paleogroundwater flow, and better understand the origin of ichnofabric-related karst features. Three case studies, which include Pleistocene carbonate rocks of the Biscayne aquifer in southern Florida and Cretaceous carbonate strata of the Edwards–Trinity aquifer system in central Texas, demonstrate that (1) there can be a strong relation between ichnofabrics and groundwater flow in carbonate aquifers and (2) ichnology can offer a useful methodology for carbonate aquifer characterization. In these examples, zones of extremely permeable, ichnofabric-related macroporosity are mappable stratiform geobodies and as such can be represented in groundwater flow and transport simulations.

  14. Activation of carbon dioxide and carbon monoxide at aluminium surfaces

    NASA Astrophysics Data System (ADS)

    Carley, A. F.; Gallagher, D. E.; Roberts, M. W.

    Dynamic photoelectron spectroscopy has shown that the adsorption of carbon dioxide at aluminium surfaces is followed by a dissociative reaction leading to the formation of a metastable surface carbonate in the temperature range 80-120 K. The carbonate is subsequently reduced (120-475 K) (deoxygenated) to generate two different forms of surface carbon, one carbidic C δ- (a) and the other less ionic C 0(a) possibly graphitic. Quantification of the C(ls) and O(ls) spectra enable each of the species O 2-(a), CO 32-(a), C δ-(a) and C 0 (a) to be distinguished and their surface concentrations calculated over a wide temperature range. The temperature and pressure dependences of CO 2 reduction suggest the participation of a precursor dimer state (CO 2---CO 2)(a) which then disproportionates. Furthermore studies of the coadsorption of ammonia and carbon dioxide in analogous systems indicate that a discrete and specifically reactive species, O - (s), is formed during carbonate formation. The results are discussed in the context of recent theoretical studies of F REUND and M ESSMER and also comparisons made with metal-CO 2 complexes. The facile surface reduction of CO 2 via a surface carbonate suggested that a possible route to carbon-oxygen bond cleavage in carbon monoxide interaction with an sp-metal surface (aluminium) was a step-wise oxidation to CO 2 leading to surface carbonate which was then readily deoxygenated. Studies of carbon monoxide: dioxygen mixtures (100: I) confirmed that this indeed occurred. A modified E LEY-R IDEAL type mechanism involving a hopping "non-adsorbed" CO molecule and a short-lived surface O - (s) species is suggested.

  15. The oxidation behavior of carbon-carbon composites and their coatings

    SciTech Connect

    Schaeffer, J.C.

    1989-01-01

    The oxidation of carbon-carbon composites and coatings in oxygen at temperatures between 300 and 1400 C was investigated. State-of-the-art systems were characterized prior to the oxidation studies using optical and scanning electron microscopy. It was determined that uncoated carbon-carbon composites cannot be used at temperatures above about 400 C for extended periods of time because of oxidation. Oxidation does occur at temperatures below 400 C but at very low rates. Boron was found to be an ineffective inhibitor for carbon-carbon oxidation. Coatings were useful in protecting carbon-carbon composites from oxidation under isothermal test conditions but these coatings failed under cyclic conditions. The factors leading to the failure of coatings on carbon-carbon composites are described.

  16. Cofilin takes the lead.

    PubMed

    DesMarais, Vera; Ghosh, Mousumi; Eddy, Robert; Condeelis, John

    2005-01-01

    Cofilin has emerged as a key regulator of actin dynamics at the leading edge of motile cells. Through its actin-severing activity, it creates new actin barbed ends for polymerization and also depolymerizes old actin filaments. Its function is tightly regulated in the cell. Spatially, its activity is restricted by other actin-binding proteins, such as tropomyosin, which compete for accessibility of actin filament populations in different regions of the cell. At the molecular level, it is regulated by phosphorylation, pH and phosphatidylinositol (4,5)-bisphosphate binding downstream of signaling cascades. In addition, it also appears to be regulated by interactions with 14-3-3zeta and cyclase-associated protein. In vivo, cofilin acts synergistically with the Arp2/3 complex to amplify local actin polymerization responses upon cell stimulation, which gives it a central role in setting the direction of motility in crawling cells.

  17. Who will lead?

    PubMed

    Gustafson, R P; Schlosser, J R

    1997-01-01

    A recent survey conducted by the UCLA Center for Health Services Management and the Physician Executive Practice of Heidrick & Struggles, an executive search firm, sheds light on the emerging physician executive's role. The goal of the research was to identify success factors as a means of evaluating and developing effective industry leaders. Respondents were asked to look at specific skills in relation to nine categories: Communication, leadership, interpersonal skills, self-motivation/management, organizational knowledge, organizational strategy, administrative skills, and thinking. Communication, leadership, and self-motivation/management emerged, in that order, as the three most important success factors for physician executives. An individual's general competencies, work styles, and ability to lead others through organizational restructuring defines his or her appropriateness for managerial positions in the health care industry.

  18. Leading from the boardroom.

    PubMed

    Lorsch, Jay W; Clark, Robert C

    2008-04-01

    These days, boards are working overtime to comply with Sarbanes-Oxley and other governance requirements meant to protect shareholders from executive wrongdoing. But as directors have become more hands-on with compliance, they've become more hands-off with long-range planning. That exposes corporations and their shareholders to another--perhaps even greater--risk, say professors Lorsch, of Harvard Business School, and Clark, of Harvard Law School. Boards are giving the long term short shrift for a number of reasons. Despite much heavier workloads, directors haven't rethought their patterns of operating - their meetings, committees, and other interactions. Compliance has changed their relationship with executives, however, turning directors into micromanagers who closely probe executives' actions instead of providing high-level guidance. Meanwhile, the pressure to meet quarterly expectations intensifies. Directors need to do a better job of balancing compliance with forward thinking. Boardroom effectiveness hinges most on the quality of directors and their interactions, the authors' research shows. Directors must apply their wisdom broadly, handling compliance work more efficiently and staying out of the weeds on strategic issues. Using their power with management to evangelize for long-term planning, they must take the lead on discussions about financial infrastructure, talent development, and strategy. Reserving sacrosanct time for such discussions, as Philips Electronics' board does at annual retreats, is an effective practice: After one recent retreat, Philips decided to exit the semiconductor business, where it was losing ground. Individual directors also must not shy away from asking tough questions and acting as catalysts on critical issues, such as grooming a successor to the CEO. In short, directors must learn to lead from the boardroom.

  19. Antiferroelectricity in lead zirconate

    NASA Astrophysics Data System (ADS)

    Tagantsev, Alexander K.

    2014-03-01

    Antiferroelectrics are essential ingredients for widely applied piezoelectric and ferroelectric materials. Despite their technological importance, the reason why materials become antiferroelectric has remained allusive since their first discovery. Experimentally, antiferroelectrics can be recognized as materials that exhibit a structural phase transition between two non-polar phases with a strong dielectric anomaly at the high temperature side of the transition. Despite a widely spread opinion that these materials can be viewed as direct analogues of antiferromagnetics, the so-called anti-polar ionic displacements at the transition do not guaranty the antiferroelectric behavior of the material while the interpretation of such behavior does not require the incorporation of the anti-polar ionic displacements in the scenario. To get insight in the true origin of antiferroelectricity, we studied the lattice dynamics of the antiferroelectric lead zirconate using inelastic and diffuse X-ray scattering techniques and the Brillouin light scattering. Based on our experimental data, we showed that the driving force for antiferroelectricity is a ferroelectric instability. Through flexoelectric coupling, it drives the system to a state, which is virtually unstable against incommensurate modulations. However, the Umklapp interaction allows the system to go directly to the commensurate lock-in phase, leaving the incommensurate phase as a ``missed'' opportunity. By this mechanism the ferroelectric softening is transformed into an antiferroelectric transition. The remaining key parts of the whole scenario are repulsive and attractive biquadratic couplings that suppress the appearance of the spontaneous polarization and induce the anti-phase octahedral rotations in the low-temperature phase. The analysis of the results reveals that the antiferroelectric state is a ``missed'' incommensurate phase, and that the paraelectric to antiferroelectric phase transition is driven by the

  20. Carbon-On-Carbon Manufacturing

    NASA Technical Reports Server (NTRS)

    Mungas, Gregory S. (Inventor); Buchanan, Larry (Inventor); Banzon, Jr., Jose T. (Inventor)

    2017-01-01

    The presently disclosed technology relates to carbon-on-carbon (C/C) manufacturing techniques and the resulting C/C products. One aspect of the manufacturing techniques disclosed herein utilizes two distinct curing operations that occur at different times and/or using different temperatures. The resulting C/C products are substantially non-porous, even though the curing operation(s) substantially gasify a liquid carbon-entrained filler material that saturates a carbon fabric that makes up the C/C products.

  1. Intermediate Temperature Carbon - Carbon Composite Structures. CRADA Final Report

    SciTech Connect

    Lara-Curzio, Edgar

    2007-06-01

    The objective of this Cooperative Research and Development Agreement (CRADA) between UT-Battelle, LLC (the "Contractor") and Synterials, Inc. (the "Participant") was to demonstrate promising processing methods, which can lead to producing Carbon-Carbon Composites (CCC), with tensile and interlaminar properties comparable to those of organic matrix composites and environmental stability at 1200 F for long periods of time. The participant synthesized carbon-carbon composites with two different fiber coatings and three different matrices. Both parties evaluated the tensile and interlaminar properties of these materials and characterized the microstructure of the matrices and interfaces. It was found that fiber coatings of carbon and boron carbide provided the best environmental protection and resulted in composites with high tensile strength.

  2. Carbon photonics

    SciTech Connect

    Konov, V I

    2015-11-30

    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)

  3. KENNEDY SPACE CENTER, FLA. - Jim Landy, NDE specialist with USA, points to an area of a Reinforced Carbon Carbon panel just examined using flash thermography. A relatively new procedure at KSC, thermography uses high intensity light to heat areas of the panels. The panels are then immediately scanned with an infrared camera. As the panels cool, any internal flaws are revealed. The gray carbon composite RCC panels are attached to the leading edge of the wing of the orbiters. They have sufficient strength to withstand the aerodynamic forces experienced during launch and reentry, which can reach as high as 800 pounds per square foot. The operating range of RCC is from minus 250º F to about 3,000º F, the temperature produced by friction with the atmosphere during reentry. The panels will be installed on the orbiter Discovery, designated for the first Return to Flight mission, STS-114.

    NASA Image and Video Library

    2004-03-10

    KENNEDY SPACE CENTER, FLA. - Jim Landy, NDE specialist with USA, points to an area of a Reinforced Carbon Carbon panel just examined using flash thermography. A relatively new procedure at KSC, thermography uses high intensity light to heat areas of the panels. The panels are then immediately scanned with an infrared camera. As the panels cool, any internal flaws are revealed. The gray carbon composite RCC panels are attached to the leading edge of the wing of the orbiters. They have sufficient strength to withstand the aerodynamic forces experienced during launch and reentry, which can reach as high as 800 pounds per square foot. The operating range of RCC is from minus 250º F to about 3,000º F, the temperature produced by friction with the atmosphere during reentry. The panels will be installed on the orbiter Discovery, designated for the first Return to Flight mission, STS-114.

  4. KENNEDY SPACE CENTER, FLA. - Jim Landy, NDE specialist with United Space Alliance (USA), prepares equipment to examine a Reinforced Carbon Carbon panel using flash thermography. A relatively new procedure at KSC, thermography uses high intensity light to heat areas of the panels. The panels are then immediately scanned with an infrared camera. As the panels cool, any internal flaws are revealed. The gray carbon composite RCC panels are attached to the leading edge of the wing of the orbiters. They have sufficient strength to withstand the aerodynamic forces experienced during launch and reentry, which can reach as high as 800 pounds per square foot. The operating range of RCC is from minus 250º F to about 3,000º F, the temperature produced by friction with the atmosphere during reentry. The panels will be installed on the orbiter Discovery, designated for the first Return to Flight mission, STS-114.

    NASA Image and Video Library

    2004-03-10

    KENNEDY SPACE CENTER, FLA. - Jim Landy, NDE specialist with United Space Alliance (USA), prepares equipment to examine a Reinforced Carbon Carbon panel using flash thermography. A relatively new procedure at KSC, thermography uses high intensity light to heat areas of the panels. The panels are then immediately scanned with an infrared camera. As the panels cool, any internal flaws are revealed. The gray carbon composite RCC panels are attached to the leading edge of the wing of the orbiters. They have sufficient strength to withstand the aerodynamic forces experienced during launch and reentry, which can reach as high as 800 pounds per square foot. The operating range of RCC is from minus 250º F to about 3,000º F, the temperature produced by friction with the atmosphere during reentry. The panels will be installed on the orbiter Discovery, designated for the first Return to Flight mission, STS-114.

  5. KENNEDY SPACE CENTER, FLA. - Jim Landy, NDE specialist with United Space Alliance, sets up equipment to examine a Reinforced Carbon Carbon panel using flash thermography. A relatively new procedure at KSC, thermography uses high intensity light to heat areas of the panels. The panels are then immediately scanned with an infrared camera. As the panels cool, any internal flaws are revealed. The gray carbon composite RCC panels are attached to the leading edge of the wing of the orbiters. They have sufficient strength to withstand the aerodynamic forces experienced during launch and reentry, which can reach as high as 800 pounds per square foot. The operating range of RCC is from minus 250º F to about 3,000º F, the temperature produced by friction with the atmosphere during reentry. The panels will be installed on the orbiter Discovery, designated for the first Return to Flight mission, STS-114.

    NASA Image and Video Library

    2004-03-10

    KENNEDY SPACE CENTER, FLA. - Jim Landy, NDE specialist with United Space Alliance, sets up equipment to examine a Reinforced Carbon Carbon panel using flash thermography. A relatively new procedure at KSC, thermography uses high intensity light to heat areas of the panels. The panels are then immediately scanned with an infrared camera. As the panels cool, any internal flaws are revealed. The gray carbon composite RCC panels are attached to the leading edge of the wing of the orbiters. They have sufficient strength to withstand the aerodynamic forces experienced during launch and reentry, which can reach as high as 800 pounds per square foot. The operating range of RCC is from minus 250º F to about 3,000º F, the temperature produced by friction with the atmosphere during reentry. The panels will be installed on the orbiter Discovery, designated for the first Return to Flight mission, STS-114.

  6. KENNEDY SPACE CENTER, FLA. - Jim Landy, NDE specialist with United Space Alliance (USA), examines a Reinforced Carbon Carbon panel using flash thermography. A relatively new procedure at KSC, thermography uses high intensity light to heat areas of the panels. The panels are then immediately scanned with an infrared camera. As the panels cool, any internal flaws are revealed. The gray carbon composite RCC panels are attached to the leading edge of the wing of the orbiters. They have sufficient strength to withstand the aerodynamic forces experienced during launch and reentry, which can reach as high as 800 pounds per square foot. The operating range of RCC is from minus 250º F to about 3,000º F, the temperature produced by friction with the atmosphere during reentry. The panels will be installed on the orbiter Discovery, designated for the first Return to Flight mission, STS-114.

    NASA Image and Video Library

    2004-03-10

    KENNEDY SPACE CENTER, FLA. - Jim Landy, NDE specialist with United Space Alliance (USA), examines a Reinforced Carbon Carbon panel using flash thermography. A relatively new procedure at KSC, thermography uses high intensity light to heat areas of the panels. The panels are then immediately scanned with an infrared camera. As the panels cool, any internal flaws are revealed. The gray carbon composite RCC panels are attached to the leading edge of the wing of the orbiters. They have sufficient strength to withstand the aerodynamic forces experienced during launch and reentry, which can reach as high as 800 pounds per square foot. The operating range of RCC is from minus 250º F to about 3,000º F, the temperature produced by friction with the atmosphere during reentry. The panels will be installed on the orbiter Discovery, designated for the first Return to Flight mission, STS-114.

  7. Lead absorption in cows: biological indicators of ambient lead exposure

    SciTech Connect

    Karacic, V.; Prpic-Majic, D.; Skender, L.

    1984-03-01

    In order to determine actual lead exposure from residual amounts of lead in the environmental soil following the introduction of effective engineering emission controls in a lead smeltery, the absorption of lead in cows grazing in the vicinity was investigated. Four groups of cows were examined: two groups of cows exposed to different ambient lead concentration, compared with two normal groups of cows. In each cow aminolevulinic acid dehydratase (ALAD), erythrocyte protoporphyrin (EP) and blood lead (Pb-B) were determined, two years prior to and four years after the technical sanitation of the lead emission source. The results demonstrated normalization of ALAD, EP and Pb-B after the technical sanitation. In spite of normalization, biological indicators ALAD and Pb-B determined four years after the technical sanitation showed increased lead absorption in comparison with the results of the control group. This indirectly indicates lead contamination of the environment from residual amounts of lead in the soil.

  8. Adsorption of lead over graphite oxide.

    PubMed

    Olanipekun, Opeyemi; Oyefusi, Adebola; Neelgund, Gururaj M; Oki, Aderemi

    2014-01-24

    The adsorption efficiency and kinetics of removal of lead in presence of graphite oxide (GO) was determined using the Atomic Absorption Spectrophotometer (AAS). The GO was prepared by the chemical oxidation of graphite and characterized using FTIR, SEM, TGA and XRD. The adsorption efficiency of GO for the solution containing 50, 100 and 150 ppm of Pb(2+) was found to be 98%, 91% and 71% respectively. The adsorption ability of GO was found to be higher than graphite. Therefore, the oxidation of activated carbon in removal of heavy metals may be a viable option to reduce pollution in portable water. Published by Elsevier B.V.

  9. Adsorption of lead over Graphite Oxide

    PubMed Central

    Olanipekun, Opeyemi; Oyefusi, Adebola; Neelgund, Gururaj M.; Oki, Aderemi

    2014-01-01

    The adsorption efficiency and kinetics of removal of lead in presence of graphite oxide (GO) was determined using the Atomic Absorption spectrophotometer (AAS). The GO was prepared by the chemical oxidation of graphite and characterized using FTIR, SEM, TGA and XRD. The adsorption efficiency of GO for the solution containing 50, 100 and 150 ppm of Pb2+ was found to be 98, 91 and 71% respectively. The adsorption ability of GO was found to be higher than graphite. Therefore, the oxidation of activated carbon in removal of heavy metals may be a viable option to reduce pollution in portable water. PMID:24152870

  10. Adsorption of lead over graphite oxide

    NASA Astrophysics Data System (ADS)

    Olanipekun, Opeyemi; Oyefusi, Adebola; Neelgund, Gururaj M.; Oki, Aderemi

    2014-01-01

    The adsorption efficiency and kinetics of removal of lead in presence of graphite oxide (GO) was determined using the Atomic Absorption Spectrophotometer (AAS). The GO was prepared by the chemical oxidation of graphite and characterized using FTIR, SEM, TGA and XRD. The adsorption efficiency of GO for the solution containing 50, 100 and 150 ppm of Pb2+ was found to be 98%, 91% and 71% respectively. The adsorption ability of GO was found to be higher than graphite. Therefore, the oxidation of activated carbon in removal of heavy metals may be a viable option to reduce pollution in portable water.

  11. Allegre's Lead Paradox Revisited

    NASA Astrophysics Data System (ADS)

    Hofmann, A. W.; Goldstein, S. L.; Class, C.

    2007-12-01

    Allegre (1969), using a generalized Concordia plot, was first to note that in a 4.55 Ga old Earth, Pb has been removed from the mantle in preference to U, even though magmatism tends to do the opposite. He noted that this "contradiction" might require a separate reservoir where the missing lead is stored. This "contradiction", more commonly expressed by the conventional Holmes-Houtermans diagram, has become known as the "lead paradox." Several models have been proposed to resolve it, ranging from late "core pumping" of Pb (as suggested by Allègre) to Pb storage in the mantle transition zone (Murphy et al. 2003) or in ancient parts of the lower continental crust. The idea of late core pumping has recently been revived by Wood & Halliday (2005) who suggested that Pb was sequestered through late sulfide segregation into the core. Here we propose that crystallization of Ca-perovskite, accompanied by segregation of a dense silicate melt toward the core-mantle boundary, can account for the apparently elevated U/Pb ratio of the accessible silicate Earth, particularly if the partition coefficient for U and Th in Ca-perovskite is as high as 400 as suggested by Corgne and Wood (2005). Such a dense liquid is the inferred consequence of the measured crossover of melting temperatures of silicate perovskite and ferro-periclase at about 1200 km depth, and the predicted Fe-rich eutectic and low melting temperatures in the lowermost mantle (Boehler, 2000). In addition, lower-mantle melt segregation with residual Ca-perovskite will cause a decrease in Nb/Ta from the primitive (chondritic) value in the accessible mantle, another, more recently discovered puzzle of mantle geochemistry. Downward segregation of a dense melt fraction and final solidification of the lowermost mantle may have been a slow process requiring more than 100 Ma, and involving a substantial fraction of the mantle. We suggest that this process served to stabilize the D'' reservoir storing solar noble gases

  12. Premium carbon products from coal

    SciTech Connect

    Rusinko, F. Jr.; Morrison, J.L.

    2000-07-01

    The face of the US coal industry and its markets are changing. Environmental concerns over global warming and plant emissions are two factors that will continue to gain national attention and consequently will challenge the use of coal in the US within its traditional markets. The decline of coke production in the US has lead to high quality metallurgical-grade coal being used to generate electricity. One could argue this is a waste of a limited valuable resource. The debate over global warming and the generation of greenhouse gases, particularly CO{sub 2}, will undoubtedly negatively impact the use of coal in newly constructed power plants. What is the future of the US coal industry and the industries that benefit from coal? This paper will review the use of coal and coal-derived materials in new, non-fuel markets. It will review a new industrial consortium that has recently been formed to stimulate the use of coal in value-added carbon markets. One of the questions the reader should ask when reading this paper is: Is coal more valuable for its carbon content or its BTU content? Carbon materials such as carbon fibers, carbon-carbon composites, specialty and mechanical graphite, activated carbon, carbon black, and carbon foams may provide new markets for the coal industry. These markets are expanding and some of these markets are in their infancy. These new material applications offer an exciting, but little recognized, opportunity for the expanded use of coal.

  13. Carbon dioxide-assisted fabrication of highly uniform submicron-sized colloidal carbon spheres via hydrothermal carbonization using soft drink

    SciTech Connect

    Moon, Gun-Hee; Shin, Yongsoon; Arey, Bruce W.; Wang, Chong M.; Exarhos, Gregory J.; Choi, Wonyong; Liu, Jun

    2012-10-01

    An eco-friendly and economical method for the formation of uniform-sized carbon spheres by hydrothermal dehydration/condensation of a commercial carbonated beverage at 200 oC is reported. CO2 dissolved in the beverage accelerates the dehydration kinetics of the dissolved sugar molecules leading to production of homogeneous carbon spheres having a diameter less than 850 nm. In the presence of CO2, the rough surface of these carbon spheres likely results from continuous Ostwald ripening of constituent microscopic carbon-containing spheres that are formed by subsequent polymerization of intermediate HMF molecules.

  14. Carbon-Carbon Piston Architectures

    NASA Technical Reports Server (NTRS)

    Rivers, H. Kevin (Inventor); Ransone, Philip O. (Inventor); Northam, G. Burton (Inventor); Schwind, Francis A. (Inventor)

    2000-01-01

    An improved structure for carbon-carbon composite piston architectures is disclosed. The improvement consists of replacing the knitted fiber, three-dimensional piston preform architecture described in U.S. Pat.No. 4,909,133 (Taylor et al.) with a two-dimensional lay-up or molding of carbon fiber fabric or tape. Initially, the carbon fabric of tape layers are prepregged with carbonaceous organic resins and/or pitches and are laid up or molded about a mandrel, to form a carbon-fiber reinforced organic-matrix composite part shaped like a "U" channel, a "T"-bar, or a combination of the two. The molded carbon-fiber reinforced organic-matrix composite part is then pyrolized in an inert atmosphere, to convert the organic matrix materials to carbon. At this point, cylindrical piston blanks are cored from the "U"-channel, "T"-bar, or combination part. These blanks are then densified by reimpregnation with resins or pitches which are subsequently carbonized. Densification is also accomplished by direct infiltration with carbon by vapor deposition processes. Once the desired density has been achieved, the piston billets are machined to final piston dimensions; coated with oxidation sealants; and/or coated with a catalyst. When compared to conventional steel or aluminum alloy pistons, the use of carbon-carbon composite pistons reduces the overall weight of the engine; allows for operation at higher temperatures without a loss of strength; allows for quieter operation; reduces the heat loss; and reduces the level of hydrocarbon emissions.

  15. Lead-acid battery

    NASA Technical Reports Server (NTRS)

    Rowlette, John J. (Inventor)

    1983-01-01

    A light weight lead-acid battery (30) having a positive terminal (36) and a negative terminal (34) and including one or more cells or grid stacks having a plurality of vertically stacked conductive monoplates (10, 20) with positive active material and negative active material deposited on alternating plates in the cell or grid stack. Electrolyte layers (26, 28) positioned between each monoplate are included to provide a battery cell having four sides which is capable of being electrically charged and discharged. Two vertical positive bus bars (42, 43) are provided on opposite sides of the battery cell for connecting the monoplates (10) with positive active material together in parallel current conducting relation. In addition, two negative bus bars (38, 39) on opposite sides of the battery cell each being adjacent the positive bus bars are provided for connecting the monoplates (20) with negative active material together in parallel current conducting relation. The positive (42, 43) and negative (38, 39) bus bars not only provide a low resistance method for connecting the plurality of conductive monoplates of their respective battery terminals (36, 34) but also provides support and structural strength to the battery cell structure. In addition, horizontal orientation of monoplates (10, 20) is provided in a vertical stacking arrangement to reduce electrolyte stratification and short circuiting due to flaking of positive and negative active materials from the monoplates.

  16. Factors leading to dermatophytosis.

    PubMed

    Qadim, Hamideh Herizchi; Golforoushan, Farideh; Azimi, Hamideh; Goldust, Mohamad

    2013-01-01

    Tinea or dermatophytoses are of skin superficial and fungous infections affecting keratinized tissues such as hair, nail, and superficial layer of epidermis. This study aimed at evaluating some predisposing factors for tinea corporis, because elimination or treatment of them not only ceases spreading of the lesion but also prevents reinfection. In this descriptive cross-sectional study patients who were visited in Sina Hospital in Tabriz and had confirmed tinea corporis with direct fungal smear were selected. Other regarding were age, sex, occupation and predisposing factors. Of 76 confirmed cases, 46 (60.5%) were males and 30 (30.5%) were females. Tinea corporis was common in the third decade. The main predisposing factor was dry skin. Diabetes was found only in 4 (5.2%) patients. According to the results of the present research, xerosis was the most common factor leading to tinea corporis in these patients rather than diabetes or lymphoma that it's diagnosis, treatment and some simple educations may inhence improvement of tinea corporis and prevents other superficial infections too.

  17. Europa's Leading Hemisphere

    NASA Technical Reports Server (NTRS)

    1997-01-01

    This image of Europa's leading hemisphere was obtained by the solid state imaging (CCD) system on board NASA's Galileo spacecraft during its seventh orbit of Jupiter. In the upper left part of the image is Tyre, a multi-ringed structure that may have formed as a result of an ancient impact. Also visible are numerous lineaments that extend for over 1000 kilometers. The limb, or edge, of Europa in this image can be used by scientists to constrain the radius and shape of the satellite. North is to the top of the picture and the sun illuminates the surface from the right. The image, centered at -40 latitude and 180 longitude, covers an area approximately 2000 by 1300 kilometers. The finest details that can be discerned in this picture are about 6.6 kilometers across. The images were taken on April 3, 1997 at 17 hours, 42 minutes, 19 seconds Universal Time when the spacecraft was at a range of 31,8628 kilometers.

    The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.

    This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at URL http://www.jpl.nasa.gov/galileo/sepo

  18. DETERMINANTS OF RESIDENTIAL LEAD EXPOSURE

    EPA Science Inventory

    The phase-out of leaded gasoline, and the accompanying decrease in lead emissions, resulted in a dramatic decline in mean blood lead levels from the late 1970s through the early 1990s. Nonetheless, lead exposures remain a public health concern. Long-term exposures to even low...

  19. Lead contamination of urban snow.

    PubMed

    Grandstaff, D E; Myer, G H

    1979-01-01

    Lead content of newly fallen snow in an urban area ranges from 34 to 56 ppb. After falling, snow may incorporate major additional amounts of lead by dry deposition of lead aerosols from local sources. The highest concentration found was 2,700 ppb. Ingestion of lead-contaminated snow might pose a health hazard to inner city children.

  20. DETERMINANTS OF RESIDENTIAL LEAD EXPOSURE

    EPA Science Inventory

    The phase-out of leaded gasoline, and the accompanying decrease in lead emissions, resulted in a dramatic decline in mean blood lead levels from the late 1970s through the early 1990s. Nonetheless, lead exposures remain a public health concern. Long-term exposures to even low...

  1. Lead line in rodents: an old sign of lead intoxication turned into a new method for environmental surveillance.

    PubMed

    de Figueiredo, Fellipe Augusto Tocchini; Ramos, Junia; Kawakita, Erika R Hashimoto; Bilal, Alina S; de Sousa, Frederico B; Swaim, William D; Issa, Joao P Mardegan; Gerlach, Raquel F

    2016-11-01

    The "lead line" was described by Henry Burton in 1840. Rodents are used as sentinels to monitor environmental pollution, but their teeth have not been used to determine lead. To determine whether lead deposits can be observed in the teeth of lead-exposed animals, since the gingival deposits known as "lead line" would likely have a correlate in the calcified tissue to which the gums are opposed during life. Male Wistar rats were exposed to lead in the drinking water (30 mg/L) since birth until 60 days-old. Molars and the incisors of each hemimandible were analyzed by scanning electron microscopy (SEM) on regular and backscattered electrons (BSE) mode. Elements were determined using electron dispersive spectroscopy (EDS). Clean cervical margins were observed on control teeth, as opposed to the findings of extensive deposits on lead-exposed animals, even in hemimandibles that had been exhumed after being buried for 90 days. BSE/EDS indicated that those deposits were an exogenous material compatible with lead sulfite. Presence of calcium, phosphorus, magnesium, carbon, lead, and oxygen is presented. Lead-exposed animals presented marked root resorption. The lead deposits characterized here for the first time show that the "lead line" seen in gums has a calcified tissue counterpart, that is detectable post-mortem even in animals exposed to a low dose of lead. This is likely a good method to detect undue lead exposure and will likely have wide application for pollution surveillance using sentinels.

  2. Leading Your Leaders

    NASA Technical Reports Server (NTRS)

    Hale, Wayne N.

    2008-01-01

    life is good. More often when an unbelievably difficult test fails, we are left with a very long discussion of why and what was wrong in the design or execution of the test. Make sure that the test is well defined. Even then, it is important to explain to your leaders what inherent accuracy (or error) the test conditions or equipment have and what the assumptions or initial conditions were for the test. Test results without a good understanding of the test's accuracy or the pedigree of the test assumptions are worth very little. Finally, there is flight test data. Always limited, never at the edge of the envelope, it still shows how the real hardware works in a combined environment. Flight experience is dangerous because it typically doesn't show how close to the edge of the cliff the equipment is operating, but it does demonstrate how the hardware really works. A flight test is the ultimate test, again taken with the knowledge that it is probably not the extreme but something more like the middle of the environmental and systems performance. Good understanding of a problem and its solution always relies on a combination of all these methods. Be sure to lead your leaders by using all the tools you have at your disposal. At the end of the day, decisions in space flight always come down to a risk trade. Our business is not remotely safe, not in the sense that the public, the media, or our legislators use the term. Everything we do has a risk, cost, schedule, or performance trade-off. For your leaders to make an appropriate decision, you need to educate them, lead them, talk with them, and engage them in the discussion until full understanding takes place. It's your job. *

  3. Leading clever people.

    PubMed

    Goffee, Rob; Jones, Gareth

    2007-03-01

    In an economy driven by ideas and intellectual know-how, top executives recognize the importance of employing smart, highly creative people. But if clever people have one defining characteristic, it's that they do not want to be led. So what is a leader to do? The authors conducted more than 100 interviews with leaders and their clever people at major organizations such as PricewaterhouseCoopers, Cisco Systems, Novartis, the BBC, and Roche. What they learned is that the psychological relationships effective leaders have with their clever people are very different from the ones they have with traditional followers. Those relationships can be shaped by seven characteristics that clever people share: They know their worth--and they know you have to employ them if you want their tacit skills. They are organizationally savvy and will seek the company context in which their interests are most generously funded. They ignore corporate hierarchy; although intellectual status is important to them, you can't lure them with promotions. They expect instant access to top management, and if they don't get it, they may think the organization doesn't take their work seriously. They are plugged into highly developed knowledge networks, which both increases their value and makes them more of a flight risk. They have a low boredom threshold, so you have to keep them challenged and committed. They won't thank you--even when you're leading them well. The trick is to act like a benevolent guardian: to grant them the respect and recognition they demand, protect them from organizational rules and politics, and give them room to pursue private efforts and even to fail. The payoff will be a flourishing crop of creative minds that will enrich your whole organization.

  4. Materials science. Electronics without lead.

    PubMed

    Li, Yi; Moon, Kyoung-sik; Wong, C P

    2005-06-03

    In conventional consumer electronics such as cell phones, lead-containing interconnects provide the conductive path between different circuit elements. Environmental concerns have led to a search for lead-free alternatives. In their Perspective, Li et al. review these efforts, which have focused on lead-free alloys and electrically conductive adhesives. Both of these approaches are showing promise, but no one lead-free interconnect material can serve as a substitute for the conventional tin-lead solder in all devices.

  5. Carbon cyclist

    NASA Astrophysics Data System (ADS)

    Showstack, Randy

    A satellite launched in early August as part of NASA's Mission to Planet Earth could dramatically increase understanding of how carbon cycles through the Earth's biosphere and living organisms and how this process influences global climate. The Sea-viewing Wide Field-of-View Sensor (SeaWiFS) will measure the color of the oceans with a radiometer to determine the concentration of chlorophyll found in oceanic phytoplankton. The single-celled plants, at the base of food chains around the world, remove carbon dioxide from seawater through photosynthesis, which allows oceans to absorb more carbon dioxide from the atmosphere.

  6. Development of X-43A Mach 10 Leading Edges

    NASA Technical Reports Server (NTRS)

    Ohlhorst, Craig W.; Glass, David E.; Bruce, Walter E., III; Lindell, Michael C.; Vaughn, Wallace L.; Dirling, R. B., Jr.; Hogenson, P. A.; Nichols, J. M.; Risner, N. W.; Thompson, D. R.

    2005-01-01

    The nose leading edge of the Hyper-X Mach 10 vehicle was orginally anticipated to reach temperatures near 4000 F at the leading-edge stagnation line. A SiC coated carbon/carbon (C/C) leading-edge material will not survive that extreme temperature for even a short duration single flight. To identify a suitable leading edge for the Mach 10 vehicle, arc-jet testing was performed on thirteen leading-edge segments fabricated from different material systems to evaluate their performance in a simulated flight environment. Hf, Zr, Si, and Ir based materials, in most cases as a coating on C/C, were included in the evaluation. Afterwards, MER, Tucson, AZ was selected as the supplier of the flight vehicle leading edges. The nose and the vertical and horizontal tail leading edges were fabricated out of a 3:1 biased high thermal conductivity C/C. The leading edges were coated with a three layer coating comprised of a SiC conversion of the top surface of the C/C, followed by a chemical vapor deposited layer of SiC, followed by a thin chemical vapor deposited layer of HfC. This paper will describe the fabrication of the Mach 10 C/C leading edges and the testing performed to validate performance.

  7. Carbon and graphite matrices in carbon-carbon composites: An overview of their formation, structure, and properties. Technical report

    SciTech Connect

    Rellick, G.S.

    1992-10-23

    Carbon-carbon (C/C) composites, so called because they combine carbon-fiber reinforcement in an all-carbon matrix, can best be viewed as part of the broader category of carbon-fiber-based composites, all of which seek to utilize the light weight and exceptional strength and stiffness of carbon fibers. In C/C particularly, the structural benefits of carbon-fiber reinforcement are combined with the high-temperature capability of an all-carbon materials system, making C/C composites the material of choice for severe-environment applications. Their dimensional stability, laser hardness, and low outgassing also make such composites ideal candidates for various space structural applications. In this overview report, the various fiber architectures used in composite fabrication, i.e., the manner in which the fibers are oriented relative to each other, are discussed briefly. However, the main topic is the carbon matrix and leads to a review of the different approaches for obtaining carbon matrices; specifically, the use of chemical vapor deposition (CVD) of carbon from natural gas (methane), coal-tar and petroleum pitches, and thermosetting resins. In the latter two approaches, the pitch- or resin-matrix composite first produced is baked or fired, to pyrolyze the organic matrix and yield a carbon matrix. The structure of the carbon matrix is characterized by a variety of techniques: X-ray diffraction, laser Raman microprobe spectroscopy, density measurements, polarized-light microscopy, and scanning and transmission electron microscopy (SEM and TEM).

  8. Reducing lead exposure in children

    SciTech Connect

    Farfel, M.R.

    1985-01-01

    The near elimination of lead-related childhood fatalities and encephalopathy by the 1970s and the sharp decline in mean blood lead levels nationwide documented between 1976 and 1980 are two milestones in the fight against lead poisoning. In the case of the latter, we know the antecedents, such as controls on the sale, use, and lead content of lead paint, improved chelation therapy, and increased awareness and case finding; however, the antecedents' relative contributions are not known due to a lack of evaluation. Similarly, the effect of a variety of social-welfare programs has not been evaluated. Since the 1970s, our perception of the problem of lead toxicity and consequently its control has changed. First steps have been made toward attaining one primary preventive objective, controlling the multiple sources of new inputs of lead to the biosphere that contribute to asymptomatic lead toxicity. The lead content of widely used commodities has been reduced (canned foods and gasoline) or virtually eliminated (paint). The benefits of passive measures used to attain reductions in lead exposure have been documented to a greater extent than those of active programs. The best example of a successful primary and passive preventive measure is the availability of lead-free gasoline since 1974, which largely accounts for decreases in ambient air lead concentrations nationwide and the recent shift to lower values in the distribution curve of children's blood lead levels. The latter provides a margin of safety for children before known toxic levels are reached. The contribution of reductions in dietary lead to changes in blood lead levels has not been well documented. Studies also show the benefits of the use of lead-free paint in new housing. Compared to children living in older homes with deteriorating lead paint, those living in lead-free homes are at low risk for lead toxicity.

  9. Developments in carbon materials

    NASA Technical Reports Server (NTRS)

    Burchell, Timothy D.

    1994-01-01

    The following carbon-based materials are reviewed and their applications discussed: fullerenes; graphite (synthetic and manufactured); activated carbon fibers; and carbon-carbon composites. Carbon R&D activities at ORNL are emphasized.

  10. The lead industry and lead water pipes "A Modest Campaign".

    PubMed

    Rabin, Richard

    2008-09-01

    Lead pipes for carrying drinking water were well recognized as a cause of lead poisoning by the late 1800s in the United States. By the 1920s, many cities and towns were prohibiting or restricting their use. To combat this trend, the lead industry carried out a prolonged and effective campaign to promote the use of lead pipes. Led by the Lead Industries Association (LIA), representatives were sent to speak with plumbers' organizations, local water authorities, architects, and federal officials. The LIA also published numerous articles and books that extolled the advantages of lead over other materials and gave practical advice on the installation and repair of lead pipes. The LIA's activities over several decades therefore contributed to the present-day public health and economic cost of lead water pipes.

  11. Calcium Carbonate.

    PubMed

    Al Omari, M M H; Rashid, I S; Qinna, N A; Jaber, A M; Badwan, A A

    2016-01-01

    Calcium carbonate is a chemical compound with the formula CaCO3 formed by three main elements: carbon, oxygen, and calcium. It is a common substance found in rocks in all parts of the world (most notably as limestone), and is the main component of shells of marine organisms, snails, coal balls, pearls, and eggshells. CaCO3 exists in different polymorphs, each with specific stability that depends on a diversity of variables. © 2016 Elsevier Inc. All rights reserved.

  12. Functionalization of carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Korneva, Guzeliya

    Carbon nanotubes have unique properties that make them attractive for different engineering applications. However, because of their chemical inertness, carbon nanotubes have to be functionalized in order to acquire additional physico-chemical properties. Large multiwalled carbon nanotubes are different from fullerenes and singlewalled nanotubes because the stresses in their walls are almost relaxed while most chemical methods for fullerene functionalization exploit this effect of stressed bonds. The objective of this work is to develop new methods for functionalization of multiwalled carbon nanotubes. This work is dedicated to study two functionalization methods. The first deals with physico-chemical functionalization by filling the nanotube interior with colloidal suspensions. Irreversible adsorption of functional nanoparticles on the nanotube wall leads to the nanotube functionalization. The second method is purely chemical functionalization, which uses the reaction of cyclopropanation to break pi-bonds in the benzene rings of the nanotubes with formation of new σ-bonds with deprotonated malonate. This so-called Bingel reaction has been used in fullerene chemistry and in this work was applied for the first time to functionalize multiwalled carbon nanotubes. While capillary filling of carbon nanotubes was known long ago, the research community was skeptical about possibility of engulfing nanoparticles into nanotubes by capillary forces. We developed and implemented capillary method to fill nanotubes with different nanoparticles. Using this method, magnetic carbon nanotubes were produced for the first time. Synthesized nanotubes have very high magnetic moment and allow to manipulate them by magnetic field. These magnetic nanotubes have been successfully used in fabrication of carbon nanotube-tipped pipettes for biological probes. The Bingel reaction was studied on three sets of multiwalled carbon nanotubes with diameters: 20nm, 100nm, and 300nm. To estimate the

  13. Infiltrated carbon foam composites

    NASA Technical Reports Server (NTRS)

    Lucas, Rick D. (Inventor); Danford, Harry E. (Inventor); Plucinski, Janusz W. (Inventor); Merriman, Douglas J. (Inventor); Blacker, Jesse M. (Inventor)

    2012-01-01

    An infiltrated carbon foam composite and method for making the composite is described. The infiltrated carbon foam composite may include a carbonized carbon aerogel in cells of a carbon foam body and a resin is infiltrated into the carbon foam body filling the cells of the carbon foam body and spaces around the carbonized carbon aerogel. The infiltrated carbon foam composites may be useful for mid-density ablative thermal protection systems.

  14. Task 4 supporting technology. Part 1: Detailed test plan for leading edge tile development. Leading edge material development and testing

    NASA Technical Reports Server (NTRS)

    Hogenson, P. A.; Staszak, Paul; Hinkle, Karrie

    1995-01-01

    This task develops two alternative candidate tile materials for leading edge applications: coated alumina enhanced thermal barrier (AETB) tile and silicone impregnated reusable ceramic ablator (SIRCA) tile. Upon reentry of the X-33/RLV space vehicle, the leading edges experience the highest heating rates and temperatures. The wing leading edge and nose cap experience peak temperatures in the range 2000 to 2700 F. Replacing reinforced carbon-carbon (RCC) with tile-based thermal protection system (TPS) materials is the primary objective. Weight, complexity, coating impact damage, and repairability are among the problems that this tile technology development addresses. The following subtasks will be performed in this development effort: tile coating development; SIRCA tile development; robustness testing of tiles; tile repair development; tile operations/processing; tile leading edge configuration; and life cycle testing.

  15. Home refinishing, lead paint, and infant blood lead levels.

    PubMed Central

    Rabinowitz, M; Leviton, A; Bellinger, D

    1985-01-01

    We measured the blood lead levels of 249 infants semi-annually from birth to two years of age; we sampled the home paint and recorded any recent home refinishing activity. Mean blood lead from birth to age 2 years did not vary systematically with age but did correlate significantly with the amount of lead in the indoor paint (p less than .01). Refinishing activity in homes with high lead paint was associated with elevations of blood lead averaging 69 per cent. PMID:3976969

  16. Biogeochemistry: The soil carbon erosion paradox

    NASA Astrophysics Data System (ADS)

    Sanderman, Jonathan; Berhe, Asmeret Asefaw

    2017-04-01

    Erosion is typically thought to degrade soil resources. However, the redistribution of soil carbon across the landscape, caused by erosion, can actually lead to a substantial sink for atmospheric CO2.

  17. Safety and Health Topics: Lead

    MedlinePlus

    ... A Spanish version is also available. Lead Battery Manufacturing eTool . OSHA. Management Guidelines for Blood Lead Levels ... exposure occurs in most industry sectors including construction, manufacturing, wholesale trade, transportation, remediation and even recreation. Construction ...

  18. Lead leaching from pressure cookers.

    PubMed

    Raghunath, R; Nambi, K S

    1998-12-11

    Leachability of lead by tap water and tamarind solution from Indian pressure cookers while cooking with and without a safety valve is studied. Lead contamination of food by cookers is not very high when compared to the daily intake of lead from various food items consumed by the Indian community. However, looking at the very wide range of lead levels leached from various brands of pressure cookers, it certainly seems possible to keep the lead contamination to the minimum by proper choice of the materials used in the manufacture of these pressure cookers. The rubber gasket, which is a very important component of any pressure cooker, contains the maximum lead concentration; the safety valve is another important source leading to lead contamination of cooked food.

  19. Lead testing wipes contain measurable background levels of lead.

    PubMed

    Keenan, James J; Le, Matthew H; Paustenbach, Dennis J; Gaffney, Shannon H

    2010-03-01

    Lead is registered under the California Safe Drinking Water and Toxic Enforcement Act of 1986 (Proposition 65) as both a carcinogen and a reproductive hazard. As part of the process to determine if consumer products satisfy Proposition 65 with respect to lead, various wipe sampling strategies have been utilized. Four commonly used wipe materials (cotton gauze, cotton balls, ashless filter paper, and Ghost Wipes) were tested for background lead levels. Ghost Wipe material was found to have 0.43 +/- 0.11 microg lead/sample (0.14 microg/wipe). Wipe testing for lead using Ghost Wipes may therefore result in measurable concentrations of lead, regardless of whether or not the consumer product actually contains leachable lead.

  20. Carbon Nanotube Solar Cells

    PubMed Central

    Klinger, Colin; Patel, Yogeshwari; Postma, Henk W. Ch.

    2012-01-01

    We present proof-of-concept all-carbon solar cells. They are made of a photoactive side of predominantly semiconducting nanotubes for photoconversion and a counter electrode made of a natural mixture of carbon nanotubes or graphite, connected by a liquid electrolyte through a redox reaction. The cells do not require rare source materials such as In or Pt, nor high-grade semiconductor processing equipment, do not rely on dye for photoconversion and therefore do not bleach, and are easy to fabricate using a spray-paint technique. We observe that cells with a lower concentration of carbon nanotubes on the active semiconducting electrode perform better than cells with a higher concentration of nanotubes. This effect is contrary to the expectation that a larger number of nanotubes would lead to more photoconversion and therefore more power generation. We attribute this to the presence of metallic nanotubes that provide a short for photo-excited electrons, bypassing the load. We demonstrate optimization strategies that improve cell efficiency by orders of magnitude. Once it is possible to make semiconducting-only carbon nanotube films, that may provide the greatest efficiency improvement. PMID:22655070

  1. Carbon nanotube solar cells.

    PubMed

    Klinger, Colin; Patel, Yogeshwari; Postma, Henk W Ch

    2012-01-01

    We present proof-of-concept all-carbon solar cells. They are made of a photoactive side of predominantly semiconducting nanotubes for photoconversion and a counter electrode made of a natural mixture of carbon nanotubes or graphite, connected by a liquid electrolyte through a redox reaction. The cells do not require rare source materials such as In or Pt, nor high-grade semiconductor processing equipment, do not rely on dye for photoconversion and therefore do not bleach, and are easy to fabricate using a spray-paint technique. We observe that cells with a lower concentration of carbon nanotubes on the active semiconducting electrode perform better than cells with a higher concentration of nanotubes. This effect is contrary to the expectation that a larger number of nanotubes would lead to more photoconversion and therefore more power generation. We attribute this to the presence of metallic nanotubes that provide a short for photo-excited electrons, bypassing the load. We demonstrate optimization strategies that improve cell efficiency by orders of magnitude. Once it is possible to make semiconducting-only carbon nanotube films, that may provide the greatest efficiency improvement.

  2. Holder for Tinning Microcircuit Leads

    NASA Technical Reports Server (NTRS)

    Gilbert, G. G.; Fielder, G. D.

    1986-01-01

    Heat-sinking tool holds microcircuits for lead tinning while protecting circuits from heat of tinning solder. Microcircuit holder dips leads in molten solder. Holder shields microcircuit from solder heat while leads immersed and absorbs heat conducted through leads. Thus keeps microcircuit relatively cool. Application tool was developed for requires tinning not closer than 0.02 in. (0.5 mm) from package body or its glass seals.

  3. The ecotoxicology of lead shot and lead fishing weights.

    PubMed

    Scheuhammer, A M; Norris, S L

    1996-10-01

    : Lead shot ingestion is the primary source of elevated lead exposure and poisoning in waterfowl and most other bird species. For some species (e.g. Common Loons, Gavia immer), lead sinker ingestion is a more frequent cause of lead poisoning. In freshwater environments where recreational angling activity and loon populations co-occur, lead poisoning from ingestion of small (<50 gram) lead sinkers or jigs accounts for 10-50% of recorded adult loon mortality, depending on the locations studied. Lead shot ingestion occurs in waterfowl, and in a wide variety of non-waterfowl species, including upland game birds, shorebirds, raptors, and scavengers. Where it has been explicitly studied in Canada and the US, lead poisoning mortality of bald (Haliacetus leucocephalus) and golden eagles (Aquila chrysactos) from eating prey animals with lead shot embedded in their tissues accounts for an estimated 10-15% of the recorded post-fledging mortality in these raptorial species. In addition to environments that experience hunting with lead shot, clay target shooting ranges, especially those in which the shotfall zones include ponds, marshes, lakes, rivers, beaches, or other aquatic-type environments, create a significant risk of shot ingestion and poisoning for waterbirds. Metallic lead pellets deposited onto soils and aquatic sediments are not chemically or environmentally inert, although tens or hundreds of years may be required for total breakdown and dissolution of pellets. Functional, affordable non-toxic alternatives to lead shot and sinkers are being currently produced, and additional such products are being developed. Several countries have successfully banned the use of small lead sinkers, and of lead shot for waterfowl and other hunting, also for clay target shooting, using a phasing-out process that gives manufactures, sellers, and users adequate time to adjust to the regulations.

  4. Lead in teeth from lead-dosed goats: Microdistribution and relationship to the cumulative lead dose

    SciTech Connect

    Bellis, David J.; Hetter, Katherine M.; Jones, Joseph; Amarasiriwardena, Dula; Parsons, Patrick J.

    2008-01-15

    Teeth are commonly used as a biomarker of long-term lead exposure. There appear to be few data, however, on the content or distribution of lead in teeth where data on specific lead intake (dose) are also available. This study describes the analysis of a convenience sample of teeth from animals that were dosed with lead for other purposes, i.e., a proficiency testing program for blood lead. Lead concentration of whole teeth obtained from 23 animals, as determined by atomic absorption spectrometry, varied from 0.6 to 80 {mu}g g{sup -1}. Linear regression of whole tooth lead ({mu}g g{sup -1}) on the cumulative lead dose received by the animal (g) yielded a slope of 1.2, with r{sup 2}=0.647 (p<0.0001). Laser ablation inductively coupled plasma mass spectrometry was employed to determine lead content at micrometer scale spatial resolution in the teeth of seven goats representing the dosing range. Highly localized concentrations of lead, ranging from about 10 to 2000 {mu}g g{sup -1}, were found in circumpulpal dentine. Linear regression of circumpulpal lead ({mu}g g{sup -1}) on cumulative lead dose (g) yielded a slope of 23 with r{sup 2}=0.961 (p=0.0001). The data indicated that whole tooth lead, and especially circumpulpal lead, of dosed goats increased linearly with cumulative lead exposure. These data suggest that circumpulpal dentine is a better biomarker of cumulative lead exposure than is whole tooth lead, at least for lead-dosed goats.

  5. Lead in teeth from lead-dosed goats: Microdistribution and relationship to the cumulative lead dose

    PubMed Central

    Bellis, David J.; Hetter, Katherine M.; Jones, Joseph; Amarasiriwardena, Dula; Parsons, Patrick J.

    2013-01-01

    Teeth are commonly used as a biomarker of long-term lead exposure. There appear to be few data, however, on the content or distribution of lead in teeth where data on specific lead intake (dose) are also available. This study describes the analysis of a convenience sample of teeth from animals that were dosed with lead for other purposes, i.e., a proficiency testing program for blood lead. Lead concentration of whole teeth obtained from 23 animals, as determined by atomic absorption spectrometry, varied from 0.6 to 80 μg g−1. Linear regression of whole tooth lead (μg g−1) on the cumulative lead dose received by the animal (g) yielded a slope of 1.2, with r2 = 0.647 (p<0.0001). Laser ablation inductively coupled plasma mass spectrometry was employed to determine lead content at micrometer scale spatial resolution in the teeth of seven goats representing the dosing range. Highly localized concentrations of lead, ranging from about 10 to 2000 μg g−1, were found in circumpulpal dentine. Linear regression of circumpulpal lead (μg g−1) on cumulative lead dose (g) yielded a slope of 23 with r2 = 0.961 (p = 0.0001). The data indicated that whole tooth lead, and especially circumpulpal lead, of dosed goats increased linearly with cumulative lead exposure. These data suggest that circumpulpal dentine is a better biomarker of cumulative lead exposure than is whole tooth lead, at least for lead-dosed goats. PMID:17644083

  6. FIELD DEMONSTRATION OF LEAD PAINT ABATEMENT TECHNOLOGIES IN RESIDENTIAL HOUSING

    EPA Science Inventory

    This study was conducted to demonstrate lead-based paint (LBP) removal from architectural wood components in CO2 unoccupied residential housing using four technologies: granular carbon dioxide (CO2 blasting), pelletized CO2 blasting, encapsulant paint remover, and wet abrasive bl...

  7. Orbiting Carbon Observatory-2 (OCO-2) Launch

    NASA Image and Video Library

    2014-07-02

    A United Launch Alliance Delta II rocket launches with the Orbiting Carbon Observatory-2 (OCO-2)satellite onboard from Space Launch Complex 2 at Vandenberg Air Force Base, Calif. on Wednesday, July 2, 2014. OCO-2 will measure the global distribution of carbon dioxide, the leading human-produced greenhouse gas driving changes in Earth’s climate. Photo Credit: (NASA/Bill Ingalls)

  8. Conductance Oscillations in Squashed Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Mehrez, H.; Anantram, M. P.; Svizhenko, A.

    2003-01-01

    A combination of molecular dynamics and electrical conductance calculations are used to probe the electromechanical properties of squashed metallic carbon nanotubes. We find that the conductance and bandgap of armchair nanotubes show oscillations upon squashing. The physical origin of these oscillations is attributed to interaction of carbon atoms with a fourth neighbor. Squashing of armchair and zigzag nanotubes ultimately leads to metallic behavior.

  9. Carbon Cost of Applying Nitrogen Fertilizer

    SciTech Connect

    Izaurralde, R Cesar C. ); Mcgill, William B.; Rosenberg, Norman J.

    2000-05-05

    When the addition of nitrogen (N) fertilizer leads to increased crop biomass, it also augments carbon (C)inputs to the soil and, hence often increases soil organic matter. Consequently, the efficient use of fertilizer N to increase crop production has also been found valuable for sequestering atmospheric carbon in soil.

  10. Processing, characterization and modeling of carbon nanofiber modified carbon/carbon composites

    NASA Astrophysics Data System (ADS)

    Samalot Rivera, Francis J.

    Carbon/Carbon (C/C) composites are used in high temperature applications because they exhibit excellent thermomechanical properties. There are several challenges associated with the processing of C/C composites that include long cycle times, formation of closed porosity within fabric woven architecture and carbonization induced cracks that can lead to reduction of mechanical properties. This work addresses various innovative approaches to reduce processing uncertainties and thereby improve thermomechanical properties of C/C by using vapor grown carbon nanofibers (VGCNFs) in conjunction with carbon fabric and precursor phenolic matrix. The different aspects of the proposed research contribute to understanding of the translation of VGCNFs properties in a C/C composite. The specific objectives of the research are; (a) To understand the mechanical properties and microstructural features of phenolic resin precursor with and without modification with VGCNFs; (b) To develop innovative processing concepts that incorporate VGCNFs by spraying them on carbon fabric and/or adding VGCNFs to the phenolic resin precursor; and characterizing the process induced thermal and mechanical properties; and (c) To develop a finite element model to evaluate the thermal stresses developed in the carbonization of carbon/phenolic with and without VGCNFs. Addition of VGCNFs to phenolic resin enhanced the thermal and physical properties in terms of flexure and interlaminar properties, storage modulus and glass transition temperature and lowered the coefficient of thermal expansion. The approaches of spraying VGCNFs on the fabric surface and mixing VGCNFs with the phenolic resin was found to be effective in enhancing mechanical and thermal properties of the resulting C/C composites. Fiber bridging, improved carbon yield and minimization of carbonization-induced damage were the benefits of incorporating VGCNFs in C/C composites. Carbonization induced matrix cracking predicted by the finite

  11. Blood Test: Lead (For Parents)

    MedlinePlus

    ... TV, Video Games, and the Internet Blood Test: Lead KidsHealth > For Parents > Blood Test: Lead Print A A A What's in this article? ... Análisis de sangre: plomo What It Is A lead test is used to determine the amount of ...

  12. Aluminum-Lead Composite Materials

    NASA Astrophysics Data System (ADS)

    Kovtunov, A. I.; Khokhlov, Yu. Yu.; Myamin, S. V.

    2017-05-01

    A process of fabrication of aluminum-lead sliding bearings is suggested on the basis of impregnation of foam aluminum with lead or lead-base alloys. The results of tests of physical, mechanical and operating properties of the composite materials are presented.

  13. Lead in School Drinking Water.

    ERIC Educational Resources Information Center

    Environmental Protection Agency, Washington, DC. Office of Water Programs.

    Lead levels in school drinking water merit special concern because children are more at risk than adults from exposure to lead. This manual provides ways in which school officials can minimize this risk. It assists administrators by providing: (1) general information on the significance of lead in school drinking water and its effects on children;…

  14. Blood Test: Lead (For Parents)

    MedlinePlus

    ... Your 1- to 2-Year-Old Blood Test: Lead KidsHealth > For Parents > Blood Test: Lead A A A What's in this article? What ... Análisis de sangre: plomo What It Is A lead test is used to determine the amount of ...

  15. Breakthrough: Lead-free Solder

    SciTech Connect

    Anderson, Iver

    2012-01-01

    Ames Laboratory senior metallurgist Iver Anderson explains the importance of lead-free solder in taking hazardous lead out of the environment by eliminating it from discarded computers and electronics that wind up in landfills. Anderson led a team that developed a tin-silver-copper replacement for traditional lead-tin solder that has been adopted by more than 50 companies worldwide.

  16. Breakthrough: Lead-free Solder

    ScienceCinema

    Anderson, Iver

    2016-07-12

    Ames Laboratory senior metallurgist Iver Anderson explains the importance of lead-free solder in taking hazardous lead out of the environment by eliminating it from discarded computers and electronics that wind up in landfills. Anderson led a team that developed a tin-silver-copper replacement for traditional lead-tin solder that has been adopted by more than 50 companies worldwide.

  17. Environmental Lead and Children's Health.

    ERIC Educational Resources Information Center

    Lewis, Marie

    This paper discusses the threat to children's health posed by environmental exposure to lead, focusing on public policy issues surrounding lead exposure in New South Wales (NSW), Australia. In Australia, the current blood lead level at which there is a health concern is at or above 25 micrograms per deciliter (ug/dl) of blood for infants and…

  18. The Changing Way of Leading

    ERIC Educational Resources Information Center

    Sytsma, Sandra

    2009-01-01

    This conceptual article explores the changing way of leading. It proposes that in contrast to the primarily outer actions that characterize educational change, the inner and outer dimensions of leaders are necessary to change what constitutes leading, thereby making it more appropriate to our times. The unfolding of leading actions and the…

  19. Lead bioaccessibility in 12 contaminated soils from China: Correlation to lead relative bioavailability and lead in different fractions.

    PubMed

    Li, Jie; Li, Kan; Cave, Mark; Li, Hong-Bo; Ma, Lena Q

    2015-09-15

    This study investigated the relationship between Pb relative bioavailability (RBA) and bioaccessibility, and their relationships with Pb in different pools in soils. Twelve Pb-contaminated soils representing different contamination sources from China were analyzed for Pb bioaccessibility using four in vitro methods (UBM, SBRC, IVG, and PBET), Pb-RBA using a mouse blood model, and Pb fractionation using sequential extraction. Lead bioaccessibility in the gastric phase (GP) and Pb-RBA was generally lower in mining soils (0.46-29% and 7.0-26%) than smelting (19-92% and 31-84%) and farming soils (13-99% and 51-61%), with more Pb in the residual fraction in mining soils. Lead bioaccessibility varied with assays, with SBRC (3.0-99%) producing significantly higher bioaccessible Pb than other assays (0.46-84%) in the gastric phase. However, Pb bioaccessibility in the intestinal phase (IP) of all assays sharply decreased to 0.01-20% possibly due to Pb sorption to solid phase at higher pH. Lead bioaccessibility by UBM-GP assay was best correlated with Pb-RBA (r(2) = 0.67), followed by IVG-GP (r(2) = 0.55). Among different Pb fractions, strong correlation was found between Pb bioaccessibility/Pb-RBA and the sum of exchangeable and carbonate fractions. Our study suggested that UBM-GP assay has potential to determine Pb bioaccessibility in contaminated soils in China. Published by Elsevier B.V.

  20. Lead exposure among lead-acid battery workers in Jamaica.

    PubMed

    Matte, T D; Figueroa, J P; Burr, G; Flesch, J P; Keenlyside, R A; Baker, E L

    1989-01-01

    To assess lead exposure in the Jamaican lead-acid battery industry, we surveyed three battery manufacturers (including 46 production workers) and 10 battery repair shops (including 23 battery repair workers). Engineering controls and respiratory protection were judged to be inadequate at battery manufacturers and battery repair shops. At manufacturers, 38 of 42 air samples for lead exceeded a work-shift time-weighted average concentration of 0.050 mg/m3 (range 0.030-5.3 mg/m3), and nine samples exceeded 0.50 mg/m3. Only one of seven air samples at repair shops exceeded 0.050 mg/m3 (range 0.003-0.066 mg/m3). Repair shop workers, however, had higher blood lead levels than manufacturing workers (65% vs. 28% with blood lead levels above 60 micrograms/dl, respectively). Manufacturing workers had a higher prevalence of safe hygienic practices and a recent interval of minimal production had occurred at one of the battery manufacturers. Workers with blood lead levels above 60 micrograms/dl tended to have higher prevalences of most symptoms of lead toxicity than did workers with lower blood lead levels, but this finding was not consistent or statistically significant. The relationship between zinc protoporphyrin concentrations and increasing blood lead concentrations was consistent with that described among workers in developed countries. The high risk of lead toxicity among Jamaican battery workers is consistent with studies of battery workers in other developing countries.