Science.gov

Sample records for metal distribution transformers

  1. Amorphous metal distribution transformers: The energy-efficient alternative

    SciTech Connect

    Garrity, T.F.

    1994-12-31

    Amorphous metal distribution transformers have been commercially available for the past 13 years. During that time, they have realized the promise of exceptionally high core efficiency as compared to silicon steel transformer cores. Utility planners today must consider all options available to meet the requirements of load growth. While additional generation capacity will be added, many demand-side initiatives are being undertaken as complementary programs to generation expansion. The efficiency improvement provided by amorphous metal distribution transformers deserves to be among the demand-side options. The key to understanding the positive impact of amorphous metal transformer efficiency is to consider the aggregate contribution those transformers can make towards demand reduction. It is estimated that distribution transformer core losses comprise at least 1% of the utility`s peak demand. Because core losses are continuous, any significant reduction in their magnitude is of great significance to the planner. This paper describes the system-wide economic contributions amorphous metal distribution transformers can make to a utility and suggests evaluation techniques that can be used. As a conservation tool, the amorphous metal transformer contributes to reduced power plant emissions. Calibration of those emissions reductions is also discussed in the paper.

  2. Field Performance of Three-Phase Amorphous Metal Core Distribution Transformers at Pearl Harbor, Hawaii

    DTIC Science & Technology

    1990-08-01

    37 Waste water management and sanitary engineering Airfields and pavements 38 O1 pollution removal and recovery3 Air polution ADVANCED BASE AND...utility systems at Ford Island, Barbers Point Naval Air Station, the Naval Shipyard, and the Naval Supply Center at Pearl Harbor, Hawaii. The main...Power Meter connected to a three-phase 4-wire amorphous core transformer under test at Barbers Point Naval Air Station. This testing procedure was

  3. Impacts of one century of wastewater discharge on soil transformation through ferrolysis and related metal pollutant distributions.

    PubMed

    van Oort, Folkert; Thiry, Médard; Foy, Eddy; Fujisaki, Kenji; Delarue, Ghislaine; Dairon, Romain; Jongmans, Toine

    2017-07-15

    Discharge of wastewater leading to notable soil surface contamination is widely reported. But few works highlight the fast dynamics of soils and their morphological transformations that may result from such anthropogenic activities. Near Paris (France), sandy Luvisols were irrigated with urban wastewater since the 1890s. Within and outside the discharge area, the soil cover presents decameter-sized cryogenic structures. We studied macro morphological soil characteristics, soil chemistry and clay mineralogy on selected bulk samples, as well as contemporary pedofeatures and related metal pollutant distribution patterns in soil thin sections from subsurface horizons. Annual repetitive waterlogging and drying cycles initiated a hydromorphic soil forming process: ferrolysis, based on iron reduction producing alkalinity under anaerobic conditions, and iron oxidation producing acidity in aerobic conditions. Its intensity was enhanced at the top of thick clay-rich B-horizons in the center of cryogenic structures. The polygonal soil structure favored the evacuating of soil water and alkalinity. Within one century, such recurrent alternating redox conditions have led to clay destruction, removal of iron, strong bleaching of the E horizon and formation of abiotic Fe-rich pedofeatures at depth. In addition, between anaerobic clay-rich B and aerated E or C horizons, the contrasting hydrodynamic conditions enhanced manganese (Mn) oxidizing fungal activity and the formation of biotic Mn-rich pedofeatures. Both types of pedofeatures trapped metal pollutants in deep soil horizons. In our work, the impacts of centenary anthropogenic activity were amplified by millenary cryogenic structures, acting together to promote fast soil dynamics, within a few decades.

  4. Pair distribution function-derived mechanism of a single-crystal to disordered to single-crystal transformation in a hemilabile metal-organic framework

    SciTech Connect

    Allan, P. K.; Chapman, K. W.; Chupas, P. J.; Hriljac, J. A.; Renouf, C. L.; Lucas, T. C. A.; Morris, R. E.

    2012-01-01

    Flexible metal-organic frameworks (MOFs) are materials of great current interest. A small class of MOFs show flexibility driven by reversible bonding rearrangements that lead directly to unusual properties. Cu-SIP-3 is a MOF based on the 5-sulfoisophthalate ligand, where the strong copper-carboxylate bonds ensure that the three-dimensional integrity of the structure is retained while allowing bonding changes to occur at the more weakly bonding sulfonate group leading to unusual properties such as the ultra-selective adsorption of only certain gases. While the integrity of the framework remains intact during bonding changes, crystalline order is not retained at all times during the transformations. X-Ray diffraction reveals that highly crystalline single crystals lose order during the transformation before regaining crystallinity once it is complete. Here we show how X-ray pair distribution function analysis can be used to reveal the mechanism of the transformations in Cu-SIP-3, identifying the sequence of atomic displacements that occur in the disordered phase. A similar approach reveals the underlying mechanism of Cu-SIP-3's ultra-selective gas adsorption.

  5. Transformable liquid-metal nanomedicine

    PubMed Central

    Lu, Yue; Hu, Quanyin; Lin, Yiliang; Pacardo, Dennis B.; Wang, Chao; Sun, Wujin; Ligler, Frances S.; Dickey, Michael D.; Gu, Zhen

    2015-01-01

    To date, numerous inorganic nanocarriers have been explored for drug delivery systems (DDSs). However, the clinical application of inorganic formulations has often been hindered by their toxicity and failure to biodegrade. We describe here a transformable liquid-metal nanomedicine, based on a core–shell nanosphere composed of a liquid-phase eutectic gallium-indium core and a thiolated polymeric shell. This formulation can be simply produced through a sonication-mediated method with bioconjugation flexibility. The resulting nanoparticles loaded with doxorubicin (Dox) have an average diameter of 107 nm and demonstrate the capability to fuse and subsequently degrade under a mildly acidic condition, which facilitates release of Dox in acidic endosomes after cellular internalization. Equipped with hyaluronic acid, a tumour-targeting ligand, this formulation displays enhanced chemotherapeutic inhibition towards the xenograft tumour-bearing mice. This liquid metal-based DDS with fusible and degradable behaviour under physiological conditions provides a new strategy for engineering theranostic agents with low toxicity. PMID:26625944

  6. Transformable liquid-metal nanomedicine

    NASA Astrophysics Data System (ADS)

    Lu, Yue; Hu, Quanyin; Lin, Yiliang; Pacardo, Dennis B.; Wang, Chao; Sun, Wujin; Ligler, Frances S.; Dickey, Michael D.; Gu, Zhen

    2015-12-01

    To date, numerous inorganic nanocarriers have been explored for drug delivery systems (DDSs). However, the clinical application of inorganic formulations has often been hindered by their toxicity and failure to biodegrade. We describe here a transformable liquid-metal nanomedicine, based on a core-shell nanosphere composed of a liquid-phase eutectic gallium-indium core and a thiolated polymeric shell. This formulation can be simply produced through a sonication-mediated method with bioconjugation flexibility. The resulting nanoparticles loaded with doxorubicin (Dox) have an average diameter of 107 nm and demonstrate the capability to fuse and subsequently degrade under a mildly acidic condition, which facilitates release of Dox in acidic endosomes after cellular internalization. Equipped with hyaluronic acid, a tumour-targeting ligand, this formulation displays enhanced chemotherapeutic inhibition towards the xenograft tumour-bearing mice. This liquid metal-based DDS with fusible and degradable behaviour under physiological conditions provides a new strategy for engineering theranostic agents with low toxicity.

  7. 10 CFR 429.47 - Distribution transformers.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 10 Energy 3 2012-01-01 2012-01-01 false Distribution transformers. 429.47 Section 429.47 Energy... COMMERCIAL AND INDUSTRIAL EQUIPMENT Certification § 429.47 Distribution transformers. (a) Sampling plan for selection of units for testing. (1) The requirements of § 429.11 are applicable to distribution...

  8. 10 CFR 429.47 - Distribution transformers.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 10 Energy 3 2013-01-01 2013-01-01 false Distribution transformers. 429.47 Section 429.47 Energy... COMMERCIAL AND INDUSTRIAL EQUIPMENT Certification § 429.47 Distribution transformers. (a) Sampling plan for selection of units for testing. (1) The requirements of § 429.11 are applicable to distribution...

  9. 10 CFR 429.47 - Distribution transformers.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 10 Energy 3 2014-01-01 2014-01-01 false Distribution transformers. 429.47 Section 429.47 Energy... COMMERCIAL AND INDUSTRIAL EQUIPMENT Certification § 429.47 Distribution transformers. (a) Sampling plan for selection of units for testing. (1) The requirements of § 429.11 are applicable to distribution...

  10. Transformation and speciation of typical heavy metals in soil aquifer treatment system during long time recharging with secondary effluent: Depth distribution and combination.

    PubMed

    Wei, Liangliang; Wang, Kun; Noguera, Daniel R; Jiang, Junqiu; Oyserman, Ben; Zhao, Ningbo; Zhao, Qingliang; Cui, Fuyi

    2016-12-01

    Soil aquifer treatment (SAT) systems rely on extensive physical and biogeochemical processes in the vadose zone and aquifer for water quality improvement. In this study, the distribution, quantitative changes, as well as the speciation characteristics of heavy metals in different depth of soils of a two-year operated lab-scale SAT was explored. A majority of the heavy metals in the recharged secondary effluent were efficiently trapped by the steady-state operated SAT (removal efficiency ranged from 74.7% to 98.2%). Thus, significant accumulations of 31.7% for Cd, 15.9% for Cu, 15.3% for Zn and 8.6% for Cr were observed for the top soil after 730 d operation, leading to the concentration (in μg g(-1)) of those four heavy metals of the packed soil increased from 0.51, 46.7, 61.0 and 35.7 to 0.66, 54.2, 70.4 and 38.8, respectively. By contrast, the accumulation of Mn and Pb were quite low. The residual species were the predominant fraction of the six heavy metals (ranged for 59.8-82.4%), followed by oxidisable species. Although the Zn, Cr, Cd, Cu and Mn were efficiently bounded onto the oxide components within the soil, the percentage of the labile metal fractions (water-, acid-exchangeable and reducible metal fractions) exhibited a slight increasing after 2 Y operation. Significantly heavy metals accumulation and slightly decreasing of the proportion of the stable fractions indicated a potentially higher environmental hazard for those six heavy metals after long-term SAT operation (especially for Cu, Zn and Cd). Finally, a linear relationship between the accumulation rate of metal species and the variation of soil organic carbon concentration and water extractable organic carbon was demonstrated. Copyright © 2016 Elsevier Ltd. All rights reserved.

  11. Radon Transform and Light-Cone Distributions

    NASA Astrophysics Data System (ADS)

    Teryaev, O. V.

    2016-08-01

    The relevance of Radon transform for generalized and transverse momentum dependent parton distributions is discussed. The new application for conditional (fracture) parton distributions and dihadron fragmentation functions is suggested.

  12. Trace metal transformations in gasification

    SciTech Connect

    Erickson, T.A.; Zygarlicke, C.J.; O`Keefe, C.A.

    1995-08-01

    The Energy & Environmental Research Center (EERC) is carrying out an investigation that will provide methods to predict the fate of selected trace elements in integrated gasification combined cycle (IGCC) and integrated gasification fuel cell (IGFC) systems to aid in the development of methods to control the emission of trace elements determined to be air toxics. The goal of this project is to identify the effects of critical chemical and physical transformations associated with trace element behavior in IGCC and IGFC systems. The trace elements included in this project are arsenic, chromium, cadmium, mercury, nickel, selenium, and lead. The research seeks to identify and fill, experimentally and/or theoretically, data gaps that currently exist on the fate and composition of trace elements. The specific objectives are to (1) review the existing literature to identify the type and quantity of trace elements from coal gasification systems, (2) perform laboratory-scale experimentation and computer modeling to enable prediction of trace element emissions, and (3) identify methods to control trace element emissions.

  13. Structure and phase transformations in uranium metal

    NASA Astrophysics Data System (ADS)

    Axe, J. D.; Gruebel, G.; Lander, G. H.

    1994-10-01

    In common with other elemental actinides, metallic uranium exists in several allotropic forms, differing from one another by complex but subtle atomic rearrangements. This article reviews progress in understanding the successive phase transformations from the perspective of soft-mode instabilities.

  14. Structure and phase transformations in uranium metal

    SciTech Connect

    Axe, J.D.; Gruebel, G.; Lander, G.H.

    1993-12-01

    In common with other elemental actinides, metallic uranium exists in several allotropic forms, differing from one another by complex but subtle atomic rearrangements. This article reviews progress in understanding the successive phase transformations from the perspective of soft-mode instabilities.

  15. Distribution, origin, and transformation of metal and metalloid pollution in vegetable fields, irrigation water, and aerosols near a Pb-Zn mine.

    PubMed

    Luo, Liqiang; Chu, Binbin; Liu, Ying; Wang, Xiaofang; Xu, Tao; Bo, Ying

    2014-01-01

    Pollution of arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), lead (Pb), and zinc (Zn) in vegetable fields was investigated near a Pb-Zn mine that has been exploited for over 50 years without a tailing reservoir. A total of 205 water, soil, and aerosol samples were taken and quantified by combined chemical, spectrometric, and mineral analytical methods. The pollution origins were identified by Pb isotopes and the pathways of transformation and transport of the elements and minerals was studied. The data showed that the vegetable fields were seriously polluted by As, Cd, and Pb. Some concentrations in the samples were beyond the regulatory levels and not suitable for agricultural activities. This study revealed that: (1) particulate matter is a major pollution source and an important carrier of mineral particles and pollutants; (2) the elements from the polluted water and soils were strongly correlated with each other; (3) Pb isotope ratios from the samples show that Pb minerals were the major pollution sources in the nearby vegetable fields, and the aerosols were the main carrier of mining pollution; (4) the alkaline, rich-carbonate, and wet conditions in this area promoted the weathering and transformation of galena into the secondary minerals, anglesite and cerussite, which are significant evidence of such processes; (5) the soil and the aerosols are a recycled secondary pollution source for each other when being re-suspended with wind.Highlights• Mining activities generated heavy metal pollution in fields around a Pb-Zn mine• The elements from water and soils are strongly correlated• Anglesite and cerussite are evidence of galena transformation into secondary minerals• Particulate matter is an important transport carrier of pollution.

  16. Transforming for Distribution Based Logistics

    DTIC Science & Technology

    2007-11-02

    operations. Military Traffic Management Command ( MTMC ), the predecessor of the Surface Distribution and Deployment Command (SDDC), managed the...Fletcher’s proposal is the traditional MTMC (SDDC) dependency on commercial support. SDDC does not own or operate a single truck, train, plane, or ship

  17. Distribution transformer BIL reduction feasibility study

    SciTech Connect

    Baranowski, J.F.; Goedde, G.L. . Thomas A. Edison Technical Center)

    1990-01-01

    This paper summarizes an investigation into the feasibility of reducing basic insulation levels (BIL) for oil-immersed distribution transformers. A projected market makeup of popular kVA and system voltages was determined for the 5 kV to 35 kV insulation classes of pole-type and pad-mount distribution transformers. Reduced BIL design cases were used to determine the impact on the transformer's design and performance. The final results provide both industry cost and total owning cost savings.

  18. Transition metal catalyzed transformations of unsaturated molecules

    SciTech Connect

    Not Available

    1989-01-01

    In this proposal, research in three areas of transition metal catalyzed transformations of small molecules is proposed. The first encompasses metal catalyzed processes for the synthesis of several classes of carbon monoxide containing polymers. This section describes plans for metal catalyzed synthesis of (a) new alternating copolymers of carbon monoxide and olefins, (b) block copolymers consisting of segments of the olefin homopolymer and the olefin- carbon monoxide alternating copolymer, and (c) polycarbonates, polyesters and polyamides. The second section involves the examination of the chemistry of metal complexes incorporating oxo and hydrocarbyl ligands as a model for the heterogeneous oxidation of olefins and alkanes by meal oxides. Specific plans are to mimic in solution two proposed key steps in the heterogeneous oxidations. These are (a) the heterolytic cleavage of an alkyl (or allyl) C-H bond that is assisted by an oxo group, and (a) the transfer of an oxo group to the resultant metal bound alkyl (or allyl) ligand. The third section concerned with the development of a hybrid catalyst system involving both homogeneous and heterogeneous components for the oxidative functionalization of alkanes. The basic idea is to employ a transition metal in the elemental state to activate C-H bonds of alkanes and form surface alkyl groups. An additional transition metal species will be present in solution which will serve to oxidize these surface alkyl groups to ultimately yield oxidatively functionalized organic products. 57 refs.

  19. Surge characteristics and protection of distribution transformers. Final report

    SciTech Connect

    McMillen, C.J.; Schoendube, C.W.; Kaufmann, G.H.

    1984-01-01

    This report describes the results of an experimental study to determine the causes and prevention of anomalous failures of distribution transformers due to lightning. Utility surveys, literature searches, and the contractor's prior research determined the experiments performed to test the validity of probable causes. Scaled impulse tests on winding insulation and full magnitude tests on representative 95 kV BIL rated transformers were performed. The impulse tests simulated non-standard impulse wave shapes, methods of application, and simultaneous transient loading on new and aged transformers. Similar voltage and current surge tests were performed on typical 10 kV rated silicon carbide element distribution arresters and metal oxide varistor arrester elements. A new transient voltage computer program was utilized to predict the performance of 125 kV BIL transformers under the same type tests. The primary causes of anomalous failures were attributed to lightning surges entering shell type transformers with non-interlaced 240/120 volt coils, via the low voltage terminals; high rate of rise lightning surges impinging on transformers protected by separately mounted arresters; and shell type transformers using solid paper pad high-to-low insulation when tested to demonstrate their effectiveness.

  20. Distributed transform coding via source-splitting

    NASA Astrophysics Data System (ADS)

    Yahampath, Pradeepa

    2012-12-01

    Transform coding (TC) is one of the best known practical methods for quantizing high-dimensional vectors. In this article, a practical approach to distributed TC of jointly Gaussian vectors is presented. This approach, referred to as source-split distributed transform coding (SP-DTC), can be used to easily implement two terminal transform codes for any given rate-pair. The main idea is to apply source-splitting using orthogonal-transforms, so that only Wyner-Ziv (WZ) quantizers are required for compression of transform coefficients. This approach however requires optimizing the bit allocation among dependent sets of WZ quantizers. In order to solve this problem, a low-complexity tree-search algorithm based on analytical models for transform coefficient quantization is developed. A rate-distortion (RD) analysis of SP-DTCs for jointly Gaussian sources is presented, which indicates that these codes can significantly outperform the practical alternative of independent TC of each source, whenever there is a strong correlation between the sources. For practical implementation of SP-DTCs, the idea of using conditional entropy constrained (CEC) quantizers followed by Slepian-Wolf coding is explored. Experimental results obtained with SP-DTC designs based on both CEC scalar quantizers and CEC trellis-coded quantizers demonstrate that actual implementations of SP-DTCs can achieve RD performance close to the analytically predicted limits.

  1. Transforming Distance Education Curricula through Distributive Leadership

    ERIC Educational Resources Information Center

    Keppell, Mike; O'Dwyer, Carolyn; Lyon, Betsy; Childs, Merilyn

    2011-01-01

    This paper examines a core leadership strategy for transforming learning and teaching in distance education through flexible and blended learning. It focuses on a project centred on distributive leadership that involves collaboration, shared purpose, responsibility and recognition of leadership irrespective of role or position within an…

  2. Transforming Distance Education Curricula through Distributive Leadership

    ERIC Educational Resources Information Center

    Keppell, Mike; O'Dwyer, Carolyn; Lyon, Betsy; Childs, Merilyn

    2010-01-01

    This paper examines a core leadership strategy for transforming learning and teaching in distance education through flexible and blended learning. It focuses on a project centred on distributive leadership that involves collaboration, shared purpose, responsibility and recognition of leadership irrespective of role or position within an…

  3. Distributed Constrained Optimization with Semicoordinate Transformations

    NASA Technical Reports Server (NTRS)

    Macready, William; Wolpert, David

    2006-01-01

    Recent work has shown how information theory extends conventional full-rationality game theory to allow bounded rational agents. The associated mathematical framework can be used to solve constrained optimization problems. This is done by translating the problem into an iterated game, where each agent controls a different variable of the problem, so that the joint probability distribution across the agents moves gives an expected value of the objective function. The dynamics of the agents is designed to minimize a Lagrangian function of that joint distribution. Here we illustrate how the updating of the Lagrange parameters in the Lagrangian is a form of automated annealing, which focuses the joint distribution more and more tightly about the joint moves that optimize the objective function. We then investigate the use of "semicoordinate" variable transformations. These separate the joint state of the agents from the variables of the optimization problem, with the two connected by an onto mapping. We present experiments illustrating the ability of such transformations to facilitate optimization. We focus on the special kind of transformation in which the statistically independent states of the agents induces a mixture distribution over the optimization variables. Computer experiment illustrate this for &sat constraint satisfaction problems and for unconstrained minimization of NK functions.

  4. Ecotoxic heavy metals transformation by bacteria and fungi in aquatic ecosystem.

    PubMed

    Chaturvedi, Amiy Dutt; Pal, Dharm; Penta, Santhosh; Kumar, Awanish

    2015-10-01

    Water is the most important and vital molecule of our planet and covers 75% of earth surface. But it is getting polluted due to high industrial growth. The heavy metals produced by industrial activities are recurrently added to it and considered as dangerous pollutants. Increasing concentration of toxic heavy metals (Pb(2+), Cd(2+), Hg(2+), Ni(2+)) in water is a severe threat for human. Heavy metal contaminated water is highly carcinogenic and poisonous at even relatively low concentrations. When they discharged in water bodies, they dissolve in the water and are distributed in the food chain. Bacteria and fungi are efficient microbes that frequently transform heavy metals and remove toxicity. The application of bacteria and fungi may offer cost benefit in water treatment plants for heavy metal transformation and directly related to public health and environmental safety issues. The heavy metals transformation rate in water is also dependent on the enzymatic capability of microorganisms. By transforming toxic heavy metals microbes sustain aquatic and terrestrial life. Therefore the application of microbiological biomass for heavy metal transformation and removal from aquatic ecosystem is highly significant and striking. This paper reviews the microbial transformation of heavy metal, microbe metal interaction and different approaches for microbial heavy metal remediation from water bodies.

  5. Economic analysis of efficient distribution transformer trends

    SciTech Connect

    Downing, D.J.; McConnell, B.W.; Barnes, P.R.; Hadley, S.W.; Van Dyke, J.W.

    1998-03-01

    This report outlines an approach that will account for uncertainty in the development of evaluation factors used to identify transformer designs with the lowest total owning cost (TOC). The TOC methodology is described and the most highly variable parameters are discussed. The model is developed to account for uncertainties as well as statistical distributions for the important parameters. Sample calculations are presented. The TOC methodology is applied to data provided by two utilities in order to test its validity.

  6. Role of oxidative stress in transformation induced by metal mixture.

    PubMed

    Martín, Silva-Aguilar; Emilio, Rojas; Mahara, Valverde

    2011-01-01

    Metals are ubiquitous pollutants present as mixtures. In particular, mixture of arsenic-cadmium-lead is among the leading toxic agents detected in the environment. These metals have carcinogenic and cell-transforming potential. In this study, we used a two step cell transformation model, to determine the role of oxidative stress in transformation induced by a mixture of arsenic-cadmium-lead. Oxidative damage and antioxidant response were determined. Metal mixture treatment induces the increase of damage markers and the antioxidant response. Loss of cell viability and increased transforming potential were observed during the promotion phase. This finding correlated significantly with generation of reactive oxygen species. Cotreatment with N-acetyl-cysteine induces effect on the transforming capacity; while a diminution was found in initiation, in promotion phase a total block of the transforming capacity was observed. Our results suggest that oxidative stress generated by metal mixture plays an important role only in promotion phase promoting transforming capacity.

  7. Metals distributions in activated sludge systems

    SciTech Connect

    Patterson, J.W.; Kodukula, P.S.

    1984-05-01

    Despite extensive laboratory and field studies over the past 25 years, little advance has been made in prediction of metals distribution and removal in activated sludge treatment systems. This paper reports the results of carefully controlled pilot studies, from which empirical metals distribution models were developed. The models accurately predict the distribution of process stream metals at each point in the activated sludge process between the soluble and solids phases. The distribution models together with data on primary and secondary clarifier suspended solids removal efficiencies, are easily applied to predict the removals of influent metals in activated sludge systems. 36 references, 2 figures.

  8. 10 CFR 431.198 - Enforcement testing for distribution transformers.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 10 Energy 3 2011-01-01 2011-01-01 false Enforcement testing for distribution transformers. 431.198... COMMERCIAL AND INDUSTRIAL EQUIPMENT Distribution Transformers Compliance and Enforcement § 431.198 Enforcement testing for distribution transformers. (a) Test notice. Upon receiving information in...

  9. TRACE METAL TRANSFORMATION MECHANISMS DURING COAL COMBUSTION

    EPA Science Inventory

    The article reviews mechanisms governing the fate of trace metals during coal combustion and presents new theoretical results that interpret existing data. Emphasis is on predicting the size-segregated speciation of trace metals in pulverized-coal-fired power plant effluents. Thi...

  10. TRACE METAL TRANSFORMATION MECHANISMS DURING COAL COMBUSTION

    EPA Science Inventory

    The article reviews mechanisms governing the fate of trace metals during coal combustion and presents new theoretical results that interpret existing data. Emphasis is on predicting the size-segregated speciation of trace metals in pulverized-coal-fired power plant effluents. Thi...

  11. Optical characterisation of metallic meshes for space antennas transformable reflectors

    NASA Astrophysics Data System (ADS)

    Mironov, RA; Reznik, SV; Rukavishnikov, RV; Shishulina, VA; Zavaruev, VA

    2016-10-01

    The paper deals with metallic meshes for space antenna transformable reflectors. Optical characteristics of four metallic meshes (15 micron tungsten, 15 micron gold-plated tungsten, 20 micron molybdenum, and 50 micron Ni-coated steel) were investigated with the Nikolet IS50 spectrophotometer. The spectral optical characteristics of these metallic meshes in the range from 0.4 to 2.5 microns are required for thermal design of space antenna reflectors.

  12. [Transition metal mediated transformations of small molecules

    SciTech Connect

    Sen, A.

    1992-01-01

    Work on organotransition metal chemistry, homogeneous and heterogeneous catalysis is summarized. Several cationic palladium(II) complexes with bulky phosphine or pyridine ligands were discovered that are highly selective catalysts for linear dimerization of vinyl monomers and linear polymerization of p-divinylbenzene, the reactions proceeding through a carbocationic mechanism. Our studies were continued on alternating olefin-carbon monoxide copolymers. The copolymerization reaction and reactivity of copolymers were examined. New catalytic systems for alternating copolymerization of [alpha]-olefins with CO were discovered. In the case of styrene derivatives, tactic copolymers were obtained. Poly(ethylenepyrrolediyl) derivatives were synthesized from alternating ethylene-carbon monoxide copolymer and become electronic conductors when doped with iodine. A catalytic system for direct synthesis of polyureas and polyoxamides from and diamines was also discovered. Pt metal catalyzed the oxidation of ethers, esters, and amines to carboxylic acids and the oxidation of olefins to 1,2-diols. Anaerobic and aerobic decomposition of molybdenum(VI)-oxoalkyl compounds were studied for heterogeneous oxidation of alkanes and olefins on Mo(VI)-oxide surfaces. Synthesis of polymer-trapped metal, metal oxide, and metal sulfide nanoclusters (size <1--10 nm) was studied.

  13. An extension of the Laplace transform to Schwartz distributions

    NASA Technical Reports Server (NTRS)

    Price, D. R.

    1974-01-01

    A characterization of the Laplace transform is developed which extends the transform to the Schwartz distributions. The class of distributions includes the impulse functions and other singular functions which occur as solutions to ordinary and partial differential equations. The standard theorems on analyticity, uniqueness, and invertibility of the transform are proved by using the characterization as the definition of the Laplace transform. The definition uses sequences of linear transformations on the space of distributions which extends the Laplace transform to another class of generalized functions, the Mikusinski operators. It is shown that the sequential definition of the transform is equivalent to Schwartz' extension of the ordinary Laplace transform to distributions but, in contrast to Schwartz' definition, does not use the distributional Fourier transform. Several theorems concerning the particular linear transformations used to define the Laplace transforms are proved. All the results proved in one dimension are extended to the n-dimensional case, but proofs are presented only for those situations that require methods different from their one-dimensional analogs.

  14. Distribution transformer performance when subjected to steep front impulses

    SciTech Connect

    Burrage, L.M.; Shaw, J.H. . Thomas A. Edison Technical Center); McConnell, B.W. )

    1990-04-01

    The experimental method and the results of subjecting arrester protected pole type distribution transformers to the combined stresses caused by the conducted steep front impulse and rated 60 Hz voltages are described. Comparisons are drawn between these results and those of similar experiments on unenergized distribution transformers. It is concluded that tank mounted direct connected arresters provide a high degree of protection to these transformers, tank mounted externally gapped or crossarm mounted arresters may not provide sufficient protection; internal transformer insulation system failures caused by the steep front impulse do not necessarily result in immediate catastrophic failures of the transformers.

  15. A lognormal distribution of metal resources

    USGS Publications Warehouse

    Singer, D.A.

    2011-01-01

    For national or global resource estimation of frequencies of metals, a lognormal distribution has commonly been recommended but not adequately tested. Tests of frequencies of Cu, Zn, Pb, Ag, and Au contents of 1 984 well-explored mineral deposits display a poor fit to the lognormal distribution. When the same metals plus Mo, Co, Nb2O3, and REE2O3 are grouped into 19 geologically defined deposit types, only eight of the 73 tests fail to be fit by lognormal distribution, and most of those failures are in two deposit types suggesting a problem with those types. Estimates of the mean and standard deviation of each of the metals in each of the deposit types are provided for modeling.

  16. Distributed feedback lasing in a metallic cavity

    NASA Astrophysics Data System (ADS)

    Zhai, Tianrui; Tong, Fei; Cao, Fengzhao; Niu, Lianze; Li, Songtao; Wang, Meng; Zhang, Xinping

    2017-09-01

    Distributed feedback (DFB) lasing is observed in a metallic cavity, which consists of a gold grating and a polymer membrane. The gold grating is prepared by evaporating a 25 nm thin film of gold on the photoresist grating fabricated by interference lithography. A 150 nm thick polymer membrane is directly attached on the gold grating, forming a suspended membrane supported by the grating ridge. The assembly method decreases the metallic contact area, which makes the mode more photonic and thereby reduces the ohmic loss of the metal. Low threshold DFB lasing can be achieved when the sample is optically pumped. The fabrication technique provides a facile way to realize plasmonic DFB polymer lasers.

  17. Reversible metal-hydride phase transformation in epitaxial films

    NASA Astrophysics Data System (ADS)

    Roytburd, Alexander L.; Boyerinas, Brad M.; Bruck, Hugh A.

    2015-03-01

    Metal-hydride phase transformations in solids commonly proceed with hysteresis. The extrinsic component of hysteresis is the result of the dissipation of energy of internal stress due to plastic deformation and fracture. It can be mitigated on the nanoscale, where plastic deformation and fracture are suppressed and the transformation proceeds through formation and evolution of coherent phases. However, the phase coherency introduces intrinsic thermodynamic hysteresis, preventing reversible transformation. In this paper, it is shown that thermodynamic hysteresis of coherent metal-hydride transformation can be eliminated in epitaxial film due to substrate constraint. Film-substrate interaction leads to formation of heterophase polydomain nanostructure with variable phase fraction which can change reversibly by varying temperature in a closed system or chemical potential in an open system.

  18. Reversible metal-hydride phase transformation in epitaxial films.

    PubMed

    Roytburd, Alexander L; Boyerinas, Brad M; Bruck, Hugh A

    2015-03-11

    Metal-hydride phase transformations in solids commonly proceed with hysteresis. The extrinsic component of hysteresis is the result of the dissipation of energy of internal stress due to plastic deformation and fracture. It can be mitigated on the nanoscale, where plastic deformation and fracture are suppressed and the transformation proceeds through formation and evolution of coherent phases. However, the phase coherency introduces intrinsic thermodynamic hysteresis, preventing reversible transformation. In this paper, it is shown that thermodynamic hysteresis of coherent metal-hydride transformation can be eliminated in epitaxial film due to substrate constraint. Film-substrate interaction leads to formation of heterophase polydomain nanostructure with variable phase fraction which can change reversibly by varying temperature in a closed system or chemical potential in an open system.

  19. Optimization of distribution transformer efficiency characteristics. Final report, March 1979

    SciTech Connect

    Not Available

    1980-06-01

    A method for distribution transformer loss evaluation was derived. The total levalized annual cost method was used and was extended to account properly for conditions of energy cost inflation, peak load growth, and transformer changeout during the evaluation period. The loss costs included were the no-load and load power losses, no-load and load reactive losses, and the energy cost of regulation. The demand and energy components of loss costs were treated separately to account correctly for the diversity of load losses and energy cost inflation. The complete distribution transformer loss evaluation equation is shown, with the nomenclature and definitions for the parameters provided. Tasks described are entitled: Establish Loss Evaluation Techniques; Compile System Cost Parameters; Compile Load Parameters and Loading Policies; Develop Transformer Cost/Performance Relationship; Define Characteristics of Multiple Efficiency Transformer Package; Minimize Life Cycle Cost Based on Single Efficiency Characteristic Transformer Design; Minimize Life Cycle Cost Based on Multiple Efficiency Characteristic Transformer Design; and Interpretation.

  20. Determination analysis of energy conservation standards for distribution transformers

    SciTech Connect

    Barnes, P.R.; Van Dyke, J.W.; McConnell, B.W.; Das, S.

    1996-07-01

    This report contains information for US DOE to use in making a determination on proposing energy conservation standards for distribution transformers as required by the Energy Policy Act of 1992. Potential for saving energy with more efficient liquid-immersed and dry-type distribution transformers could be significant because these transformers account for an estimated 140 billion kWh of the annual energy lost in the delivery of electricity. Objective was to determine whether energy conservation standards for distribution transformers would have the potential for significant energy savings, be technically feasible, and be economically justified from a national perspective. It was found that energy conservation for distribution transformers would be technically and economically feasible. Based on the energy conservation options analyzed, 3.6-13.7 quads of energy could be saved from 2000 to 2030.

  1. The probabilistic distribution of metal whisker lengths

    NASA Astrophysics Data System (ADS)

    Niraula, D.; Karpov, V. G.

    2015-11-01

    Significant reliability concerns in multiple industries are related to metal whiskers, which are random high aspect ratio filaments growing on metal surfaces and causing shorts in electronic packages. We derive a closed form expression for the probabilistic distribution of metal whisker lengths. Our consideration is based on the electrostatic theory of metal whiskers, according to which whisker growth is interrupted when its tip enters a random local "dead region" of a weak electric field. Here, we use the approximation neglecting the possibility of thermally activated escapes from the "dead regions," which is later justified. We predict a one-parameter distribution with a peak at a length that depends on the metal surface charge density and surface tension. In the intermediate range, it fits well the log-normal distribution used in the experimental studies, although it decays more rapidly in the range of very long whiskers. In addition, our theory quantitatively explains how the typical whisker concentration is much lower than that of surface grains. Finally, it predicts the stop-and-go phenomenon for some of the whiskers growth.

  2. The probabilistic distribution of metal whisker lengths

    SciTech Connect

    Niraula, D. Karpov, V. G.

    2015-11-28

    Significant reliability concerns in multiple industries are related to metal whiskers, which are random high aspect ratio filaments growing on metal surfaces and causing shorts in electronic packages. We derive a closed form expression for the probabilistic distribution of metal whisker lengths. Our consideration is based on the electrostatic theory of metal whiskers, according to which whisker growth is interrupted when its tip enters a random local “dead region” of a weak electric field. Here, we use the approximation neglecting the possibility of thermally activated escapes from the “dead regions,” which is later justified. We predict a one-parameter distribution with a peak at a length that depends on the metal surface charge density and surface tension. In the intermediate range, it fits well the log-normal distribution used in the experimental studies, although it decays more rapidly in the range of very long whiskers. In addition, our theory quantitatively explains how the typical whisker concentration is much lower than that of surface grains. Finally, it predicts the stop-and-go phenomenon for some of the whiskers growth.

  3. Diverse transformations of liquid metals between different morphologies.

    PubMed

    Sheng, Lei; Zhang, Jie; Liu, Jing

    2014-09-10

    Transformation from a film into a sphere, rapid merging of separate objects, controlled self-rotation, and planar locomotion are the very unusual phenomena observed in liquid metals under application of an electric field to a liquid metal immersed in or sprayed with water. A mechanism for these effects is suggested and potential applications - for example the recovery of liquid metal previously injected into the body for therapeutic purposes - are outlined. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Modeling of Heavy Metal Transformation in Soil Ecosystem

    NASA Astrophysics Data System (ADS)

    Kalinichenko, Kira; Nikovskaya, Galina N.

    2017-04-01

    The intensification of industrial activity leads to an increase in heavy metals pollution of soils. In our opinion, sludge from biological treatment of municipal waste water, stabilized under aerobic-anaerobic conditions (commonly known as biosolid), may be considered as concentrate of natural soil. In their chemical, physical and chemical and biological properties these systems are similar gel-like nanocomposites. These contain microorganisms, humic substances, clay, clusters of nanoparticles of heavy metal compounds, and so on involved into heteropolysaccharides matrix. It is known that microorganisms play an important role in the transformation of different nature substances in soil and its health maintenance. The regularities of transformation of heavy metal compounds in soil ecosystem were studied at the model of biosolid. At biosolid swelling its structure changing (gel-sol transition, weakening of coagulation contacts between metal containing nanoparticles, microbial cells and metabolites, loosening and even destroying of the nanocomposite structure) can occur [1, 2]. The promotion of the sludge heterotrophic microbial activities leads to solubilization of heavy metal compounds in the system. The microbiological process can be realized in alcaligeneous or acidogeneous regimes in dependence on the type of carbon source and followed by the synthesis of metabolites with the properties of flocculants and heavy metals extragents [3]. In this case the heavy metals solubilization (bioleaching) in the form of nanoparticles of hydroxycarbonate complexes or water soluble complexes with oxycarbonic acids is observed. Under the action of biosolid microorganisms the heavy metals-oxycarbonic acids complexes can be transformed (catabolised) into nano-sizing heavy metals- hydroxycarbonates complexes. These ecologically friendly complexes and microbial heteropolysaccharides are able to interact with soil colloids, stay in the top soil profile, and improve soil structure due

  5. Product Distribution Theory and Semi-Coordinate Transformations

    NASA Technical Reports Server (NTRS)

    Airiau, Stephane; Wolpert, David H.

    2004-01-01

    Product Distribution (PD) theory is a new framework for doing distributed adaptive control of a multiagent system (MAS). We introduce the technique of "coordinate transformations" in PD theory gradient descent. These transformations selectively couple a few agents with each other into "meta-agents". Intuitively, this can be viewed as a generalization of forming binding contracts between those agents. Doing this sacrifices a bit of the distributed nature of the MAS, in that there must now be communication from multiple agents in determining what joint-move is finally implemented However, as we demonstrate in computer experiments, these transformations improve the performance of the MAS.

  6. Structure Fluctuation Model of Melting and Polymorphic Transformations in Metals

    NASA Astrophysics Data System (ADS)

    Filippov, E. S.

    2017-09-01

    Relationships of volumes during thermal expansion of metals are analyzed. It is demonstrated that metals with BCC structure undergo two-step structural change at the melting point: at the beginning the BCC structure is transformed into FCC structure and then clusters are formed with K = 12 and statistical packing of atoms of the liquid phase. Before melting, hexagonal layer-by-layer (6 + 6) packed Cd and Zn change their structure from K = 6 to K = 8. Metals with FCC structure do not change the number of neighbors before melting, forming clusters with K = 12. It is shown that conditions of pre-melting and polymorphic FCC (HDP) → BCC transformations are reached for the critical volume of thermal expansion caused by leveling of fluctuations of atom and electron densities.

  7. Exploration of transformational and distributed leadership.

    PubMed

    Tomlinson, Julie

    2012-07-01

    Throughout government policy in Scotland, a new emphasis has been placed on clinical leaders as a way to improve quality and restore the public's confidence in health care. This article reports on a study that explored the leadership styles of senior charge nurses and the effects these may have on clinical teams. Findings suggest that, where there is transformational leadership and sharing of leadership roles across teams, staff are more engaged and organisational goals are met. The findings also highlight the need for better communication between senior management and clinical teams to ensure sustainable, good services.

  8. Partially transformed relaxor ferroelectric single crystals with distributed phase transformation behavior

    NASA Astrophysics Data System (ADS)

    Gallagher, John A.

    2015-11-01

    Relaxor ferroelectric single crystals such as PMN-PT and PIN-PMN-PT undergo field driven phase transformations when electrically or mechanically loaded in crystallographic directions that provide a positive driving force for the transformation. The observed behavior in certain compositions is a phase transformation distributed over a range of fields without a distinct forward or reverse coercive field. This work focuses on the material behavior that is observed when the crystals are loaded sufficiently to drive a partial transformation and then unloaded, as might occur when driving a transducer to achieve high power levels. Distributed transformations have been modeled using a normal distribution of transformation thresholds. A set of experiments was conducted to characterize the hysteresis loops that occur with the partial transformations. In this work the normal distribution model is extended to include the partial transformations that occur when the field is reversed before the transformation is complete. The resulting hysteresis loops produced by the model are in good agreement with the experimental results.

  9. Formability Evaluation of Sheet Metals Based on Global Strain Distribution

    NASA Astrophysics Data System (ADS)

    Zhang, Ling; Lin, Jianping; Min, Junying; Ye, You; Kang, Liugen

    2016-06-01

    According to the conventional methods for formability evaluation, e.g., forming limit curve (FLC), limit dome height, and total elongation, inconsistent results are observed when comparing the formability of four advanced high-strength steels (AHSS) with an ultimate tensile strength grade of 1000 MPa. The strain distribution analysis with the aid of digital image correlation technique shows that different uniform deformation capabilities of sheet metals under the same loading conditions are responsible for this inconsistency. In addition, metallurgical analysis suggests that inhomogeneous microstructure distribution and phase transformation during deformation in some materials play important roles in the uniform deformation capability of sheet metal. Limit strains on the commonly used FLC only relate to the major and minor strains of local deforming elements associated with the onset of necking. However, the formability of a sheet metal component is determined by the strain magnitudes of all deforming elements involved during the forming process. Hence, the formability evaluation of sheet metals from a global aspect is more applicable for practical engineering. A new method based on two indices (i.e., which represent global formability and uniform deformation capability, respectively) is proposed to evaluate the formability of sheet metals based on global strain distribution. The formability and evolution of deformation uniformity of the investigated AHSS at different stress states are studied with this new method. Compared with other formability evaluation methods, the new method is demonstrated to be more appropriate for practical engineering, and it is applicable to both in-plane and out-of-plane deformation. Additionally, the global formability of sheet metals can be more comprehensively understood with this new method.

  10. Transformation of heavy metal speciation during sludge drying: mechanistic insights.

    PubMed

    Weng, Huan-Xin; Ma, Xue-Wen; Fu, Feng-Xia; Zhang, Jin-Jun; Liu, Zan; Tian, Li-Xun; Liu, Chongxuan

    2014-01-30

    Speciation can fundamentally affect on the stability and toxicity of heavy metals in sludge from wastewater treatment plants. This research investigated the speciation of heavy metals in sludge from both municipal and industrial sources, and metal speciation change as a result of drying process to reduce sludge volume. The changes in sludge properties including sludge moisture content, temperature, density, and electrical conductivity were also monitored to provide insights into the mechanisms causing the change in heavy metal speciation. The results show that the drying process generally stabilized Cr, Cu, Cd, and Pb in sludge by transforming acid-soluble, reducible, and oxidizable species into structurally stable forms. Such transformation and stabilization occurred regardless of the sludge source and type, and were primarily caused by the changes in sludge properties associated with decomposition of organic matter and sulfide. The results enhanced our understanding of the geochemical behavior of heavy metals in municipal sludge, and are useful for designing a treatment system for environment-friendly disposal of sludge.

  11. Transformation of heavy metal speciation during sludge drying: mechanistic insights

    SciTech Connect

    Weng, Huanxin; Ma, Xue-Wen; Fu, Feng-Xia; Zhang, Jin-Jun; Liu, Zan; Tian, Li-Xun; Liu, Chongxuan

    2014-01-30

    Speciation can fundamentally affect on the stability and toxicity of heavy metals in sludge from wastewater treatment plants. This research investigated the speciation of heavy metals in sludge from both municipal and industrial sources, and metal speciation change as a result of drying process to reduce sludge volume. The changes in sludge properties including sludge moisture content, temperature, density, and electrical conductivity were also monitored to provide insights into the mechanisms causing the change in heavy metal speciation. The results show that the drying process generally stabilized the Cr, Cu, Cd and Pb in sludge by transforming acid-soluble, reducible and oxidizable species into structurally stable forms. Such transformation and stabilization occurred regardless of the sludge source and type, and were primarily caused by the changes in sludge properties associated with decomposition of organic matter and sulfide. The results enhanced our understanding of the geochemical behavior of heavy metals in municipal sludge, and are useful for designing a treatment system for environment-friendly disposal of sludge.

  12. Folding/Unfolding Properties of Metal Foils in Transformable Structure

    NASA Astrophysics Data System (ADS)

    Daming, Nie; Zhen, Lu; Kaifeng, Zhang

    2016-11-01

    Transformable structures are widely applied in the aerospace, temporary facilities, etc. Compared to the structures made of polyester materials, the metal foil ones occupy many special advantages while have been rarely investigated. In this study, a series of transformable structures made of four different metal materials, 6065 Al, copper, TA1 and SUS 304 stainless steel, with thickness of 0.1 mm were prepared. Moreover, the folding (i.e., compressing the structure to the lowest height with external force) and unfolding (i.e., extending the structure to the largest height with external force) behaviors of these structures were exhibited and explained by experiments. Besides, the differences and corresponding mechanisms of various materials on the folding/unfolding properties of the structures were examined and discussed.

  13. Folding/Unfolding Properties of Metal Foils in Transformable Structure

    NASA Astrophysics Data System (ADS)

    Daming, Nie; Zhen, Lu; Kaifeng, Zhang

    2017-01-01

    Transformable structures are widely applied in the aerospace, temporary facilities, etc. Compared to the structures made of polyester materials, the metal foil ones occupy many special advantages while have been rarely investigated. In this study, a series of transformable structures made of four different metal materials, 6065 Al, copper, TA1 and SUS 304 stainless steel, with thickness of 0.1 mm were prepared. Moreover, the folding (i.e., compressing the structure to the lowest height with external force) and unfolding (i.e., extending the structure to the largest height with external force) behaviors of these structures were exhibited and explained by experiments. Besides, the differences and corresponding mechanisms of various materials on the folding/unfolding properties of the structures were examined and discussed.

  14. Metallicity Distribution in the Milky Way Disk

    NASA Astrophysics Data System (ADS)

    Balser, Dana S.; Rood, R. T.; Bania, T. M.; Anderson, L. D.

    2011-01-01

    Galactic chemical evolution models are important for understanding how galaxies form and evolve. A key observational constraint for these models is the spatial distribution of abundances in the Galaxy. We use hydrogen radio recombination line and continuum free-free emission observed with the Green Bank Telescope to calculate electron temperatures in 81 Galactic HII regions. Since metals, such as oxygen, are the main coolants in the photo-ionized nebular gas, the electron temperature is directly related to the distribution of heavy elements in the Milky Way. We convert the electron temperatures to metallicity (12 + Log(O/H), based on a sub-sample of objects with both electron temperature and O/H determinations. We find a radial metallicity gradient in the Galactic disk of about -0.03 to -0.06 dex/kpc with no significant discontinuity from 4-18 kpc. This is in contrast to previous studies that found a discontinuity in the gradient at 10 kpc. The radial metallicity gradient varies with azimuth, however, suggesting that the Galactic disk is not uniformly mixed as is often assumed in chemical evolution models. The new GBT HRDS Galactic HII regions will sample a new zone in Galactic azimuth since they are systematically at the far kinematic distance. Electron temperature determinations for the HRDS nebulae may provide direct evidence for local enrichment. Moreover, the negative velocity HRDS sources are not only at the important Galactocentric radius zone of 9-12 kpc, but also lie at very large distances, > 12 kpc, from the Sun. Electron temperature determinations for these nebulae will probe the metallicity of an entirely new part of the Milky Way.

  15. Reflectance Changes during Shock-induced Phase Transformations in Metals

    SciTech Connect

    Stevens, G. D.; Turley, W. D.; Veeser, L. R.; Jensen, B. J.; Rigg, P. A.

    2010-06-01

    In performing shock wave experiments to study the characteristics of metals at high pressures, wave profiles (i.e., velocity measurements of the surface of the sample) are an established and useful way to study phase transformations. For example, a sudden change in the velocity or its slope can occur when the phase transformation induces a large volume change leading to a change in particle velocity. Allowing the shock to release into a transparent window that is in contact with the sample surface allows the study of conditions away from the shock Hugoniot. However, in cases where the wave profile is not definitive an additional phase-transformation diagnostic would be useful. Changes in the electronic structure of the atoms in the crystal offer opportunities to develop new phase-change diagnostics. We have studied optical reflectance changes for several phase transformations to see whether reflectance changes might be a generally applicable phase-transformation diagnostic. Shocks were produced by direct contact with explosives or with impacts from guns. Optical wavelengths for the reflectance measurements ranged from 355 to 700 nm. We studied samples of tin, iron, gallium, and cerium as each passed through a phase transformation during shock loading and, if observable, a reversion upon unloading. For solid-solid phase changes in tin and iron we saw small changes in the surface scattering characteristics, perhaps from voids or rough areas frozen into the surface of the sample as it transformed to a new crystal structure. For melt in gallium and cerium we saw changes in the wavelength dependence of the reflectance, and we surmise that these changes may result from changes in the crystal electronic structure. It appears that reflectance measurements can be a significant part of a larger suite of diagnostics to search for difficult-to-detect phase transformations.

  16. Exploiting Semiconductor to Metallic Phase Transformation in Layered Transition Metal Dichalcogenides for Ohmic contact Contacts

    NASA Astrophysics Data System (ADS)

    Kappera, Rajesh; Voiry, Damien; Jen, Wesley; Yalcin, Sibel Ebru; Gupta, Gautam; Mohite, Aditya; Chhowalla, Manish; Material Science department, Rutgers University, Piscataway, NJ, 08854, USA Team; CenterIntegrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, NM, 87544, US Team

    2014-03-01

    Achieving ohmic contacts to transition metal dichalcogenides (MoS2, WS2, WSe2 and MoSe2) has been a challenge for researchers owing to the formation of a large Schottky barrier between metal and semiconductor. This results in low on-currents, mobilities and sub-threshold swings in the devices made with these materials. Here we report a universal strategy using chemical approach to reversibly transform the semiconducting phase (2H) to metallic phase (1T). Taking advantage of the metallic phase, we have fabricated hybrid transistors, which have 1T phase contacts and semiconducting 2H phase of the material as the channel. The metallic phase dramatically reduces the Schottky barrier between the metal and the semiconductor thereby mitigating the high contact resistance issues. This strategy should be applicable to several other applications such as catalysis, supercapacitors and batteries. Detailed synthesis, structural, electrical and optical characterization will be described.

  17. Biomolecular Mechanisms Controlling Metal and Radionuclide Transformations in Anaeromyxobacter dehalogenans

    SciTech Connect

    Beliaev, Alexander S.; Fredrickson, James K.; Loeffler, Frank E.; Sanford, Robert A.

    2006-06-01

    Microbiological reduction and immobilization of U(VI) and Tc(VII) has been proposed as a strategy for remediating radionuclide-contaminated environments. Numerous studies focusing on the reduction kinetics and speciation of these metals have been carried out using contaminated sediment samples, microbial consortia, and pure bacterial cultures. While previous work with model organisms has increased the general understanding of radionuclide transformation processes, fundamental questions regarding radionuclide reduction mechanisms by indigenous microorganisms are poorly understood, especially under the commonly encountered scenario where multiple electron acceptors are present. Therefore, the overall goal of the proposed research is to elucidate the molecular mechanisms of radionuclide biotransformation by Anaeromyxobacter dehalogenans, a predominant member of indigenous microorganism commonly found in contaminated subsurface environments, and to assess the effects of relevant environmental factors affecting these transformation reactions.

  18. Environmental assessment of heavy metal transport and transformation in the Hangzhou Bay, China.

    PubMed

    Fang, Hongwei; Huang, Lei; Wang, Jingyu; He, Guojian; Reible, Danny

    2016-01-25

    The environmental impact of heavy metal (Cu, Cd, Zn, Pb, Ni, (90)Sr and (137)Cs) transport and transformation in the Hangzhou Bay (China) was assessed through a comprehensive model that integrates hydrodynamics, sediment and heavy metal transport. A mechanistic surface complexation model was used to estimate the adsorption and desorption of heavy metal by suspended sediment under different aqueous chemistry conditions. The dynamics of metal exchange to and from the seabed was also assessed. The primary processes regulating heavy metal distribution, i.e., convection-diffusion, adsorption-desorption, sedimentation-resuspension, as well as other physical and chemical processes related to mass exchange between adjacent sediment layers, were considered in detail. The accidental discharge of (137)Cs was simulated as an example and results showed that (137)Cs transported along the coast driven by tidal flow. Most (137)Cs distributed near the outfall and accumulated in the seabed sediment. The proposed model can be a useful tool for predicting heavy metal transport and fate and provide a theoretical basis to guide field sampling, assessment of risks and the design of remediation strategies.

  19. Effect of humic acid on transformation of soil heavy metals

    NASA Astrophysics Data System (ADS)

    Wu, Shengzhe; Li, Rui; Peng, Shuyang; Liu, Qiuyong; Zhu, Xi

    2017-06-01

    The pattern of transformation among different fractions of heavy metals in soil draws great attention. This article investigated the effect of humic acid on soil heavy metal under different pH and temperature. The results showed that with the increasing of the concentration of humic acid, the concentration of available Cu, Pb decreased greatly, though the decrease of available Cd was light. Also, pH of soil had certain impact on the concentration of available Cu, Pb, Cd while the influence of environmental temperature was minor. The removal efficiency of contaminated soil was 57.283% (Cu), 2.645% (Cd) and 15.485% (Pb) while it could reach more than 98% in contaminated solution.

  20. Transformation of metal-organic frameworks for molecular sieving membranes

    PubMed Central

    Li, Wanbin; Zhang, Yufan; Zhang, Congyang; Meng, Qin; Xu, Zehai; Su, Pengcheng; Li, Qingbiao; Shen, Chong; Fan, Zheng; Qin, Lei; Zhang, Guoliang

    2016-01-01

    The development of simple, versatile strategies for the synthesis of metal-organic framework (MOF)-derived membranes are of increasing scientific interest, but challenges exist in understanding suitable fabrication mechanisms. Here we report a route for the complete transformation of a series of MOF membranes and particles, based on multivalent cation substitution. Through our approach, the effective pore size can be reduced through the immobilization of metal salt residues in the cavities, and appropriate MOF crystal facets can be exposed, to achieve competitive molecular sieving capabilities. The method can also be used more generally for the synthesis of a variety of MOF membranes and particles. Importantly, we design and synthesize promising MOF membranes candidates that are hard to achieve through conventional methods. For example, our CuBTC/MIL-100 membrane exhibits 89, 171, 241 and 336 times higher H2 permeance than that of CO2, O2, N2 and CH4, respectively. PMID:27090597

  1. Transformation of metal-organic frameworks for molecular sieving membranes

    NASA Astrophysics Data System (ADS)

    Li, Wanbin; Zhang, Yufan; Zhang, Congyang; Meng, Qin; Xu, Zehai; Su, Pengcheng; Li, Qingbiao; Shen, Chong; Fan, Zheng; Qin, Lei; Zhang, Guoliang

    2016-04-01

    The development of simple, versatile strategies for the synthesis of metal-organic framework (MOF)-derived membranes are of increasing scientific interest, but challenges exist in understanding suitable fabrication mechanisms. Here we report a route for the complete transformation of a series of MOF membranes and particles, based on multivalent cation substitution. Through our approach, the effective pore size can be reduced through the immobilization of metal salt residues in the cavities, and appropriate MOF crystal facets can be exposed, to achieve competitive molecular sieving capabilities. The method can also be used more generally for the synthesis of a variety of MOF membranes and particles. Importantly, we design and synthesize promising MOF membranes candidates that are hard to achieve through conventional methods. For example, our CuBTC/MIL-100 membrane exhibits 89, 171, 241 and 336 times higher H2 permeance than that of CO2, O2, N2 and CH4, respectively.

  2. Nonlinearities distribution Laplace transform-homotopy perturbation method.

    PubMed

    Filobello-Nino, Uriel; Vazquez-Leal, Hector; Benhammouda, Brahim; Hernandez-Martinez, Luis; Hoyos-Reyes, Claudio; Perez-Sesma, Jose Antonio Agustin; Jimenez-Fernandez, Victor Manuel; Pereyra-Diaz, Domitilo; Marin-Hernandez, Antonio; Diaz-Sanchez, Alejandro; Huerta-Chua, Jesus; Cervantes-Perez, Juan

    2014-01-01

    This article proposes non-linearities distribution Laplace transform-homotopy perturbation method (NDLT-HPM) to find approximate solutions for linear and nonlinear differential equations with finite boundary conditions. We will see that the method is particularly relevant in case of equations with nonhomogeneous non-polynomial terms. Comparing figures between approximate and exact solutions we show the effectiveness of the proposed method.

  3. 10 CFR 431.198 - Enforcement testing for distribution transformers.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... nameplate or in marketing materials for a distribution transformer, disclosed pursuant to this part, the... basic model(s) to be selected for testing, the method of selecting the test sample, the date and time at... determination of compliance or noncompliance. (c) Sampling. The determination that a manufacturer's basic model...

  4. Metal-Support Cooperative Catalysts for Environmentally Benign Molecular Transformations.

    PubMed

    Kaneda, Kiyotomi; Mitsudome, Takato

    2017-01-01

    Metal-support cooperative catalysts have been developed for sustainable and environmentally benign molecular transformations. The active metal centers and supports in these catalysts could cooperatively activate substrates, resulting in high catalytic performance for liquid-phase reactions under mild conditions. These catalysts involved hydrotalcite-supported gold and silver nanoparticles with high catalytic activity for organic reactions such as aerobic oxidation, oxidative carbonylation, and chemoselective reduction of epoxides to alkenes and nitrostyrenes to aminostyrenes using alcohols and CO/H2 O as reducing reagents. This high catalytic performance was due to cooperative catalysis between the metal nanoparticles and basic sites of the hydrotalcite support. To increase the metal-support cooperative effect, core-shell nanostructured catalysts consisting of gold or silver nanoparticles in the core and ceria supports in the shell were designed. These core-shell nanocomposite catalysts were effective for the chemoselective hydrogenation of nitrostyrenes to aminostyrenes, unsaturated aldehydes to allyl alcohols, and alkynes to alkenes using H2 as a clean reductant. In addition, these solid catalysts could be recovered easily from the reaction mixture by simple filtration, and were reusable with high catalytic activity. © 2017 The Chemical Society of Japan & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Exploring Dwarf Galaxy Evolution through Metallicity Distributions

    NASA Astrophysics Data System (ADS)

    Ross, Teresa

    2015-01-01

    As the most numerous type of galaxy, dwarf galaxies are ideal for examining galactic evolution on small scales. Additional clues to galactic evolution come from the metallicity distribution function (MDF), which is influenced by the star formation, accretion, outflows and galaxy interactions. We derived stellar MDFs for the Leo I, Leo II, IC 1613, and Phoenix dwarf galaxies using HST images in order to examine how their evolution compares as a function of various galaxy properties. These galaxies span a range of different morphologies, masses, SFHs and distances from the MW. We fit a simple evolution model and an accretion model to the MDFs in order to quantify the effect of gas flows and enrichment within the galaxies. The MDFs of Leo II (dSph), Phoenix (dTrans) and IC 1613 (dIr) have similar shapes, though their peak metallicities differ. Additionally, we find the accretion model, over the simple model, is a better fit chemical evolution model for these three galaxies. However these best fit accretion models do not require a significant amount of additional gas to explain the MDF shapes. In contrast the chemical evolution model that best fits the narrow MDF of Leo I implies twice the additional gas accretion. The similarities in the MDF shapes of Leo II, Phoenix and IC 1613, even though these galaxies all have different morphologies, implies that the current morphology is not the driving factor in shaping the MDF of these galaxies.

  6. Advancements in Distributed Learning (ADL) Environment in Support of Transformation

    DTIC Science & Technology

    2017-01-01

    The Cambridge handbook of multimedia learning (pp. 117-133). New York, NY, USA: Cambridge University Press. [21] Fowler, B.T. (1980). The...Cambridge handbook of multimedia learning . New York, NY, USA: Cambridge University Press. [35] McKinnon, D.H., Nolan, C.J.P. and Sinclair, K.E. (2000). A...REPORT TR-HFM-212 Advancements in Distributed Learning (ADL) Environment in Support of Transformation (Progrès en apprentissage distribué (ADL) à

  7. Classification of Transient Phenomena in Distribution System using wavelet Transform

    NASA Astrophysics Data System (ADS)

    Sedighi, Alireza

    2014-05-01

    An efficient procedure for classification of transient phenomena in distribution systems is proposed in this paper. The proposed method has been applied to classify some transient phenomena such as inrush current, load switching, capacitor switching and single phase to ground fault. The new scheme is based on wavelet transform algorithm. All of the events for feature extraction and test are simulated using Electro Magnetic Transient Program (EMTP). Results show high accuracy of proposed method.

  8. Distribution Coefficients of Impurities in Metals

    NASA Astrophysics Data System (ADS)

    Pearce, J. V.

    2014-04-01

    Impurities dissolved in very pure metals at the level of parts per million often cause an elevation or depression of the freezing temperature of the order of millikelvins. This represents a significant contribution to the uncertainty of standard platinum resistance thermometer calibrations. An important parameter for characterizing the behavior of impurities is the distribution coefficient , which is the ratio of the solid solubility to liquid solubility. A knowledge of for a given binary system is essential for contemporary methods of evaluating or correcting for the effect of impurities, and it is therefore of universal interest to have the most complete set of values possible. A survey of equilibrium values of (in the low concentration limit) reported in the literature for the International Temperature Scale of 1990 fixed points of Hg, Ga, In, Sn, Zn, Al, Au, Ag, and Cu is presented. In addition, thermodynamic calculations of using MTDATA are presented for 170 binary systems. In total, the combined values of from all available sources for 430 binary systems are presented. In addition, by considering all available values of for impurities in 25 different metal solvents (1300 binary systems) enough data are available to characterize patterns in the value of for a given impurity as a function of its position in the periodic table. This enables prediction of for a significant number of binary systems for which data and calculations are unavailable. By combining data from many sources, values of for solutes (atomic number from 1 to 94) in ITS-90 fixed points from Hg to Cu are suggested, together with some tentative predicted values where literature data and calculations are unavailable.

  9. Transformations of metal species in ageing humic hydrocolloids studied by competitive ligand and metal exchange.

    PubMed

    Burba, Peter; Van den Bergh, Johan

    2004-03-01

    Transformations of metal species (particularly Al, Ca, Fe, Mg, Mn, Zn) in ageing humic hydrocolloids were studied, applying a competitive ligand and metal exchange approach. For this purpose, metal-containing hydrocolloids, freshly collected from humic-rich German bog lake waters (Hohlohsee (HO), Black Forest; Venner Moor (VM), Muensterland; Arnsberger Wald (AW), Northrhine-Westfalia) and conventionally pre-filtered through 0.45 microm membranes, were subjected on-site to an exchange with EDTA and Cu(II) ions, respectively, as a function of time. EDTA complexes gradually formed, metal fractions exchanged by Cu(II) (as well as free Cu(II) concentrations) were operationally discriminated by means of a small time-controlled tangential-flow ultrafiltration unit (nominal cutoff: 1 kDa). Metal and DOM (dissolved organic matter) fractions obtained this way were determined off-site using instrumental methods (AAS, ICP-OES, carbon analyzer). After weeks of storage, the collected hydrocolloids were studied again by this approach. The EDTA availability of colloid-bound metals (particularly Al and Fe) exhibited different ageing trends, dependent on the sample (VM: decrease of Fe availability (98-76%), HO: increase of Fe availability (76-82%)). In contrast, the Cu(II) exchange equilibria of colloid-bound metals revealed merely low availability of Al (16-38%) and Fe (5-11%) towards Cu(II) ions, also dependent on ageing effects. In particular, the conditional copper exchange constants Kex obtained from the exchange between Cu(II) ions and available metal species (such as Ca, Mg, Mn, Zn) exhibited a strong decrease (by a factor of 2-100) during sample storage, indicating considerable non-equilibria complexation of these metal ions in the original bogwaters studied on-site.

  10. Metal-Organic Frameworks for CO2 Chemical Transformations.

    PubMed

    He, Hongming; Perman, Jason A; Zhu, Guangshan; Ma, Shengqian

    2016-12-01

    Carbon dioxide (CO2 ), as the primary greenhouse gas in the atmosphere, triggers a series of environmental and energy related problems in the world. Therefore, there is an urgent need to develop multiple methods to capture and convert CO2 into useful chemical products, which can significantly improve the environment and promote sustainable development. Over the past several decades, metal-organic frameworks (MOFs) have shown outstanding heterogeneous catalytic activity due in part to their high internal surface area and chemical functionalities. These properties and the ability to synthesize MOF platforms allow experiments to test structure-function relationships for transforming CO2 into useful chemicals. Herein, recent developments are highlighted for MOFs participating as catalysts for the chemical fixation and photochemical reduction of CO2 . Finally, opportunities and challenges facing MOF catalysts are discussed in this ongoing research area.

  11. Solidification and solid-state transformation sciences in metals additive manufacturing

    DOE PAGES

    Kirka, Michael M.; Nandwana, Peeyush; Lee, Yousub; ...

    2017-02-11

    Additive manufacturing (AM) of metals is rapidly emerging as an established manufacturing process for metal components. Unlike traditional metals fabrication processes, metals fabricated via AM undergo localized thermal cycles during fabrication. As a result, AM presents the opportunity to control the liquid-solid phase transformation, i.e. material texture. But, thermal cycling presents challenges from the standpoint of solid-solid phase transformations. We will discuss the opportunities and challenges in metals AM in the context of texture control and associated solid-solid phase transformations in Ti-6Al-4V and Inconel 718.

  12. Content based image retrieval based on wavelet transform coefficients distribution.

    PubMed

    Lamard, Mathieu; Cazuguel, Guy; Quellec, Gwénolé; Bekri, Lynda; Roux, Christian; Cochener, Béatrice

    2007-01-01

    In this paper we propose a content based image retrieval method for diagnosis aid in medical fields. We characterize images without extracting significant features by using distribution of coefficients obtained by building signatures from the distribution of wavelet transform. The research is carried out by computing signature distances between the query and database images. Several signatures are proposed; they use a model of wavelet coefficient distribution. To enhance results, a weighted distance between signatures is used and an adapted wavelet base is proposed. Retrieval efficiency is given for different databases including a diabetic retinopathy, a mammography and a face database. Results are promising: the retrieval efficiency is higher than 95% for some cases using an optimization process.

  13. Influence of organic matter transformations on the bioavailability of heavy metals in a sludge based compost.

    PubMed

    Ingelmo, Florencio; Molina, Maria José; Soriano, Maria Desamparados; Gallardo, Antonio; Lapeña, Leonor

    2012-03-01

    The agricultural use of anaerobically digested sewage sludge (ADSS) as stable, mature compost implies knowing its total content in heavy metals and their bioavailability. This depends not only on the initial characteristics of the composted substrates but also on the organic matter transformations during composting which may influence the chemical form of the metals and their bioavailability. The objective of this work was to examine the relationships between the changes in the organic matter content and humus fractions, and the bioavailability of heavy metals. A detailed sampling at 0, 14, 84, and 140 days of the composting process was performed to measure C contents in humic acids (HAs), fulvic acids, (FAs) and humin, the total content of Zn, Pb, Cu, Ni, and Cd, and also their distribution into mobile and mobilisable (MB), and low bioavailability (LB) forms. Significant changes of C contents in HA, FA, and Humin, and in the FA/HA, HA/Humin and C(humus)/TOC ratios were observed during composting. The MB and LB fractions of each metal also varied significantly during composting. The MB fraction increased for Zn, Cu, Ni, and Cd, and the LB fraction increased for Pb. Stepwise linear regressions and quadratic curve estimation conducted on the MB and LB fractions of each metal as dependent on the measured organic variables suggested that Zn bioavailability was mainly associated to percentage of C in FAs. Bioavailability of Cu, Ni and Cd during composting was associated to humin and HAs. Pb concentration increased in the LB form, and its variations followed a quadratic function with the C(humus)/TOC ratio. Our results suggest that the composting process renders the metals in more available forms. The main forms of metal binding in the sludge and their availability in the final compost may be better described when metal fractionation obtained in sequential extraction and humus fractionation during composting are considered together.

  14. The Asymptotic Noise Distribution in Karhunen-Loeve Transform Eigenmodes

    PubMed Central

    Ding, Yu; Xue, Hui; Jin, Ning; Chung, Yiu-Cho; Liu, Xin; Zhang, Yongqin; Simonetti, Orlando P.

    2015-01-01

    Karhunen-Loeve Transform (KLT) is widely used in signal processing. Yet the well-accepted result is that, the noise is uniformly distributed in all eigenmodes is not accurate. We apply a result of the random matrix theory to understand the asymptotic noise distribution in KLT eigenmodes. Noise variances in noise-only eigenmodes follow the Marcenko-Pastur distribution, while noise variances in signal-dominated eigenmodes still follow the uniform distribution. Both the mathematical expectation of noise level in each eigenmode and an analytical formula of KLT filter noise reduction effect with a hard threshold were derived. Numerical simulations agree with our theoretical analysis. The noise variance of an eigenmode may deviate more than 60% from the uniform distribution. These results can be modified slightly, and generalized to non-IID (independently and identically-distributed) noise scenario. Magnetic resonance imaging experiments show that the generalized result is applicable and accurate. These generic results can help us understand the noise behavior in the KLT and related topics. PMID:26635997

  15. Delineation of First-Order Elastic Property Closures for Hexagonal Metals Using Fast Fourier Transforms

    PubMed Central

    Landry, Nicholas W.; Knezevic, Marko

    2015-01-01

    Property closures are envelopes representing the complete set of theoretically feasible macroscopic property combinations for a given material system. In this paper, we present a computational procedure based on fast Fourier transforms (FFTs) for delineation of elastic property closures for hexagonal close packed (HCP) metals. The procedure consists of building a database of non-zero Fourier transforms for each component of the elastic stiffness tensor, calculating the Fourier transforms of orientation distribution functions (ODFs), and calculating the ODF-to-elastic property bounds in the Fourier space. In earlier studies, HCP closures were computed using the generalized spherical harmonics (GSH) representation and an assumption of orthotropic sample symmetry; here, the FFT approach allowed us to successfully calculate the closures for a range of HCP metals without invoking any sample symmetry assumption. The methodology presented here facilitates for the first time computation of property closures involving normal-shear coupling stiffness coefficients. We found that the representation of these property linkages using FFTs need more terms compared to GSH representations. However, the use of FFT representations reduces the computational time involved in producing the property closures due to the use of fast FFT algorithms. Moreover, FFT algorithms are readily available as opposed to GSH codes. PMID:28793566

  16. Delineation of First-Order Elastic Property Closures for Hexagonal Metals Using Fast Fourier Transforms.

    PubMed

    Landry, Nicholas W; Knezevic, Marko

    2015-09-17

    Property closures are envelopes representing the complete set of theoretically feasible macroscopic property combinations for a given material system. In this paper, we present a computational procedure based on fast Fourier transforms (FFTs) to delineation of elastic property closures for hexagonal close packed (HCP) metals. The procedure consists of building a database of non-zero Fourier transforms for each component of the elastic stiffness tensor, calculating the Fourier transforms of orientation distribution functions (ODFs), and calculating the ODF-to-elastic property bounds in the Fourier space. In earlier studies, HCP closures were computed using the generalized spherical harmonics (GSH) representation and an assumption of orthotropic sample symmetry; here, the FFT approach allowed us to successfully calculate the closures for a range of HCP metals without invoking any sample symmetry assumption. The methodology presented here facilitates for the first time computation of property closures involving normal-shear coupling stiffness coefficients. We found that the representation of these property linkages using FFTs need more terms compared to GSH representations. However, the use of FFT representations reduces the computational time involved in producing the property closures due to the use of fast FFT algorithms. Moreover, FFT algorithms are readily available as opposed to GSH codes.

  17. Prolate rotation and metallicity gradient in the transforming dwarf galaxy Phoenix

    NASA Astrophysics Data System (ADS)

    Kacharov, Nikolay; Battaglia, Giuseppina; Rejkuba, Marina; Cole, Andrew A.; Carrera, Ricardo; Fraternali, Filippo; Wilkinson, Mark I.; Gallart, Carme G.; Irwin, Mike; Tolstoy, Eline

    2017-04-01

    Transition type dwarf galaxies are thought to be systems undergoing the process of transformation from a star-forming into a passively evolving dwarf, which makes them particularly suitable to study evolutionary processes driving the existence of different dwarf morphological types. Here we present results from a spectroscopic survey of ∼200 individual red giant branch stars in the Phoenix dwarf, the closest transition type with a comparable luminosity to 'classical' dwarf galaxies. We measure a systemic heliocentric velocity Vhelio = -21.2 ± 1.0 km s-1. Our survey reveals the clear presence of prolate rotation that is aligned with the peculiar spatial distribution of the youngest stars in Phoenix. We speculate that both features might have arisen from the same event, possibly an accretion of a smaller system. The evolved stellar population of Phoenix is relatively metal-poor (<[Fe/H] > = -1.49 ± 0.04 dex) and shows a large metallicity spread (σ[Fe/H] = 0.51 ± 0.04 dex), with a pronounced metallicity gradient of -0.13 ± 0.01 dex arcmin-1 similar to luminous, passive dwarf galaxies. We also report a discovery of an extremely metal-poor star candidate in Phoenix and discuss the importance of correcting for spatial sampling when interpreting the chemical properties of galaxies with metallicity gradients. This study presents a major leap forward in our knowledge of the internal kinematics of the Phoenix transition type dwarf galaxy and the first wide area spectroscopic survey of its metallicity properties. A table containing the measured velocities, metallicities, and CaT equivalent widths of all spectroscopic targets is available online at the CDS.

  18. 10 CFR 431.193 - Test procedures for measuring energy consumption of distribution transformers.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... distribution transformers. 431.193 Section 431.193 Energy DEPARTMENT OF ENERGY ENERGY CONSERVATION ENERGY EFFICIENCY PROGRAM FOR CERTAIN COMMERCIAL AND INDUSTRIAL EQUIPMENT Distribution Transformers Test Procedures § 431.193 Test procedures for measuring energy consumption of distribution transformers. The...

  19. 10 CFR 431.193 - Test procedures for measuring energy consumption of distribution transformers.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... distribution transformers. 431.193 Section 431.193 Energy DEPARTMENT OF ENERGY ENERGY CONSERVATION ENERGY EFFICIENCY PROGRAM FOR CERTAIN COMMERCIAL AND INDUSTRIAL EQUIPMENT Distribution Transformers Test Procedures § 431.193 Test procedures for measuring energy consumption of distribution transformers. The...

  20. 10 CFR 431.193 - Test procedures for measuring energy consumption of distribution transformers.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... distribution transformers. 431.193 Section 431.193 Energy DEPARTMENT OF ENERGY ENERGY CONSERVATION ENERGY EFFICIENCY PROGRAM FOR CERTAIN COMMERCIAL AND INDUSTRIAL EQUIPMENT Distribution Transformers Test Procedures § 431.193 Test procedures for measuring energy consumption of distribution transformers. The...

  1. 10 CFR 431.193 - Test procedures for measuring energy consumption of distribution transformers.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... distribution transformers. 431.193 Section 431.193 Energy DEPARTMENT OF ENERGY ENERGY CONSERVATION ENERGY EFFICIENCY PROGRAM FOR CERTAIN COMMERCIAL AND INDUSTRIAL EQUIPMENT Distribution Transformers Test Procedures § 431.193 Test procedures for measuring energy consumption of distribution transformers. The...

  2. 10 CFR Appendix C to Subpart C of... - Sampling Plan for Enforcement Testing of Distribution Transformers

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 10 Energy 3 2012-01-01 2012-01-01 false Sampling Plan for Enforcement Testing of Distribution Transformers C Appendix C to Subpart C of Part 429 Energy DEPARTMENT OF ENERGY ENERGY CONSERVATION... Testing of Distribution Transformers (a) When testing distribution transformers, the number of units...

  3. 10 CFR Appendix C to Subpart C of... - Sampling Plan for Enforcement Testing of Distribution Transformers

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 10 Energy 3 2014-01-01 2014-01-01 false Sampling Plan for Enforcement Testing of Distribution Transformers C Appendix C to Subpart C of Part 429 Energy DEPARTMENT OF ENERGY ENERGY CONSERVATION... Testing of Distribution Transformers (a) When testing distribution transformers, the number of units...

  4. 10 CFR Appendix C to Subpart C of... - Sampling Plan for Enforcement Testing of Distribution Transformers

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 10 Energy 3 2013-01-01 2013-01-01 false Sampling Plan for Enforcement Testing of Distribution Transformers C Appendix C to Subpart C of Part 429 Energy DEPARTMENT OF ENERGY ENERGY CONSERVATION... Testing of Distribution Transformers (a) When testing distribution transformers, the number of units...

  5. Chemically and temperature-induced phase transformations of metal vanadates

    NASA Astrophysics Data System (ADS)

    Patridge, Christopher James

    different individual beta'-Cu xV2O5 nanowires vary widely. Using scanning transmission X-ray microspectroscopy of individual beta'-CuxV2O 5 nanowires, correlations appear to exist between MIT characteristics and the markedly different orbital hybridization of vanadium and oxygen at the O K and V L absorption edges. These comprehensive nanostructure studies hint at the possibility of approaching the incredibly important realm of single-domain measurements which are needed to understand and exploit the intrinsic physical properties of materials. In addition to the bronze MIT studies, the classical MIT material vanadium dioxide, VO2, also shows new properties when scaling down to nanoscale dimensions as well as incorporation of substitutional dopants such as tungsten. X-ray absorption spectroscopy of the dopant local structure suggests an increased symmetry and depairing of V4+-V 4+, which is critical for transition to the lower temperature insulating phase thereby super-cooling the metallic phase to temperatures as low as 254 K. Mechanistic insight and structural changes associated with the intercalation of Li+ are key aspects in understanding and designing useful secondary Li ion batteries. In similarity to the MxV2O 5 studies, another metal vanadate, Ag2VO2PO 4, undergoes phase transformations due to introduction of Li and the vacancy of Ag ions. Employing a comprehensive study on Ag2VO 2PO4 using X-ray absorption spectroscopy, information about chemical state changes and rehybridization of frontier orbitals allows for a more precise understanding of how the material discharges, what, if any, intermediate phases exist during the process, and provides evidence for the posited structural stability at high depths of discharge.

  6. Phase transformations and thermodynamics of aluminum-based metallic glasses

    NASA Astrophysics Data System (ADS)

    Gao, Changhua (Michael)

    This thesis examines the thermodynamics and associated kinetics and phase transformations of the glass forming Al-Ni-Gd and Al-Fe-Gd systems. In order to fully understand the unique glass forming ability (GFA) of Al-based metallic glasses, the ternary Al-Fe-Gd and Al-Ni-Gd systems in their Al-rich corners were examined experimentally to assist in a thermodynamic assessment. The solid-state phase equilibria are determined using XRD and TEM-EDS techniques. While this work basically confirms the solid-state equilibria in Al-Fe-Gd reported previously, the ternary phase in Al-Ni-Gd system has been identified to be Al15Ni3Gd2 rather than Al16Ni 3Gd reported in the literature. DTA analysis of 24 alloys in the Al-Fe-Gd system and 42 alloys in the Al-Ni-Gd system have yielded critical temperatures pertaining to the solid-liquid transition. Based on these data and information from the literature, a self-consistent thermodynamic database for these systems has been developed using the CALPHAD technique. Parameters describing the Gibbs free energy for various phases of the Al-Gd, Al-Fe-Gd and Al-Ni-Gd systems are manually optimized in this study. Once constructed, the database is used to calculate driving forces for nucleation of crystalline phases which can qualitatively explain the phase formation sequence during crystallization at low temperatures. It was also confirmed that alloy compositions with the lowest Gibbs free energy difference between the equilibrium state and undercooled liquid state exhibit better GFA than other chemistries. Based on 250°C isothermal devitrification phase transformations of 17 Al-Ni-Gd alloys, a phase formation sequence map is constructed. Fcc-Al nanocrystals are formed first in most of the alloys studied, but eutectic crystallization of a metastable phase and fcc-Al is also observed. Addition of Al or Ni promotes fcc-Al phase formation, while increasing Gd suppresses it. The continuous heating DSC scans revealed that crystallization in Al

  7. Electron energy distributions in a metal-polymer-vacuum system

    SciTech Connect

    Yumaguzin, Yu. M.; Kornilov, V. M.; Lachinov, A. N.

    2006-08-15

    The energy distributions of electrons emitted from a metal coated with a polymer (polydiphenylene phthalide) is studied experimentally using field electron spectroscopy. A considerable decrease in the electron work function for the metal-polymer-vacuum system as compared to pure metal is observed. Analysis of the energy distributions of emitted electrons shows that the distribution in the case with the polymer is broader and displaced towards low energies, and its high-energy edge is slightly extended. The effect of emission voltage on the shape of the energy distribution of emitted electrons is studied. A model is proposed to explain the substantial decrease in the effective electron work function in the case when the metal electrode is coated with a polymer film.

  8. Spatial distribution of metals in the constructed wetlands.

    PubMed

    Kongroy, Porntawee; Tantemsapya, Netnapid; Lin, Ying-Feng; Jing, Shuh Ren; Wirojanagud, Wanpen

    2012-02-01

    Investigation of the spatial distribution of metals was conducted for two constructed wetlands used as tertiary treatment in Chia Nan University of Pharmacy and Science (CNU) and Metal Processing Industries (MPI) located in Tainan, Taiwan. These two distinguished sites were selected to compare the distribution of metals for constructed wetlands treating different types of wastewater. Along the distance, samples of water, sediment, and macrophytes were analyzed for metals including Al, Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn. Additionally, measurements of water quality including temperature, pH, EC, ORP, DO, TSS, BOD, COD, and turbidity were performed. Results show that, at CNU, wastewater contained higher organic consititute (BOD 29.3 +/- 11.7 mg/, COD 46.7 +/- 33.6 mg/L) with low metals content. Wastewater at MPI contained low level of organic consititute (BOD 7.1 +/- 3.3 mg/L, and COD 66.0 +/- 56.5 mg/L) and higher metals content. Metals distribution of both sites showed similar results where metals in the sediments in the inlet zone have greater concentrations than other areas. The constructed wetlands can remove Cd, Cu, Ni, Pb, and Zn. However, there was no removal of Al, Cr, Fe, and Mn. A distance along the constructed wetlands had no effect on metal concentrations in macrophyte and water.

  9. How to buy energy-efficient distribution transformer

    SciTech Connect

    1998-07-01

    Section 161 of the Energy Policy Act of 1992 (EPACT) encourages energy-efficient federal procurement. Executive Order 12902 and FAR section 23.704 direct agencies to purchase products in the upper 25% of energy efficiency. Agencies that use these guidelines to buy efficient products can realize substantial operating cost savings and help prevent pollution. As the world`s largest consumer, the federal government can help pull the entire US market towards greater energy efficiency, while saving taxpayer dollars. The efficiency levels in this Recommendation are the same as those in NEMA`s TP-1 standard. Additionally, the EPA/DOE ENERGY STAR{reg_sign} program identifies efficient low-voltage distribution transformers with the ENERGY STAR{reg_sign} label. Complying models meet the same efficiency criteria specified in this Recommendation (and TP-1).

  10. Liquid metal filtration and distribution using fiberglass fabric

    SciTech Connect

    Brochu, C.; Dault, R.; Tremblay, S.P.

    1996-10-01

    In the last decade, the aluminum industry has mainly focused on improving metal quality by working on furnaces and casting practices and especially on in-line treatment units. However, fiberglass fabric is widely used throughout the industry. It is specially used at the last step before the solidification process when molten metal is transferred from the trough to the ingot mold. In this regard, little effort has been reported on better understanding or using fiberglass fabric in molten aluminum filtration and distribution applications. This paper will review the fiberglass fabric options. The different fiberglass fabric coatings and finishes will be described as well as their properties and characteristics with regard to molten aluminum. Fiberglass fabric used in filtration applications will be defined as a function of selected parameters such as opening, finish, throughput, etc. Finally, metal distribution will be discussed. A better understanding of fiberglass fabric finishes and bag configuration will improve metal distribution and ultimately, the final ingot quality.

  11. PHASE TRANSFORMATIONS IN METALS AND ALLOYS (SELECTED ARTICLES),

    DTIC Science & Technology

    Contents: Stabilization of reverse martensite transformation under the influence of intraphase work hardening; and Structural changes during decomposition of supersaturated solid solution of tungsten in cobalt.

  12. Simulating the transformation of heavy metals during coal or sewage sludge combustion

    SciTech Connect

    Han, J.; Xu, M.; Yao, H.; Furuuchi, M.; Sakano, T.; Kim, H.J.

    2007-01-15

    A mathematical model (FPM) is presented to predict the transformation of heavy metals in the downstream of combustor or incinerator. The model accounts for the transformation of heavy metals through the combined effect of condensation, nucleation, coagulation, external force and thermophoresis force. The calculation of heavy metals is embodied in the post-processor appended to Fluent software. Before the simulation, velocity, temperature, PbCl{sub 2} concentration and other initial parameters are obtained by experiment. In addition, the transformation of PbCl{sub 2} is also experimentally studied. The comparison of experimental and predicted results indicate that the fine particle model (FPM) is valid for predicting the transformation of heavy metals in the downstream of incinerator or combustor.

  13. Migration and transformation rule of heavy metals in sludge during hydrolysis for protein extraction.

    PubMed

    Li, Yulong; Xue, Fei; Li, Jiebing; Xu, Shi Hong; Li, Dengxin

    2016-03-01

    The content and speciation of heavy metals can fundamentally affect the hydrolysis of sludge. This research study investigates the migration and transformation rule of heavy metals during the hydrolysis process by measuring the content of exchangeables (F1), bound to carbonates (F2), bound to Fe-Mn oxides (F3), bound to organic matter (F4), and residuals (F5) under different periods of time undergoing hydrolysis. The results show that the hydrolysis process generally stabilized Cu, Zn, Mn, Ni, Pb, Cr, and As by transforming the unstable states into structurally stable states. Such transformations and stabilization were primarily caused by the changes in local metal ion environment and bonding structure, oxidation of sulfides, pyrolyzation of organic matter, and evaporation of resulting volatile materials. An X-ray diffractometry (XRD) of the residuals conducted after hydrolysis indicated that hydrolysis did have a significant influence on the transportation and transformation of heavy metals.

  14. Recent Developments in Coinage Metal Catalyzed Transformations of Stabilized Vinyldiazo Compounds: Beyond Carbenic Pathways.

    PubMed

    López, Enol; González-Pelayo, Silvia; López, Luis A

    2017-03-01

    Transition metal-catalyzed transformations of vinyldiazo compounds have become a versatile tool in organic synthesis. Although several transition metals have been investigated for this purpose, this field has been mainly dominated by dirhodium catalysts. Remarkable levels of chemo-, regio-, diastereo- and enantioselectivity have been reached in some of these rhodium-catalyzed transformations. In the last few years coinage metals have also emerged as useful catalysts in transformations involving vinyldiazo compounds. In some cases, highly efficient catalyst-dependent protocols arising from divergent mechanistic pathways have been reported. In this Personal Account, we aim to showcase recent advances in metal coinage catalyzed transformations of vinyldiazoacetates, an exciting field of research to which our group has actively contributed in the last few years.

  15. The Metallicity Distribution of the Milky Way Bulge

    NASA Astrophysics Data System (ADS)

    Ness, M.; Freeman, K.

    2016-06-01

    The Galactic bulge of the Milky Way is made up of stars with a broad range of metallicity, -3.0 < [Fe/H] < 1 dex. The mean of the metallicity distribution function decreases as a function of height z from the plane and, more weakly, with galactic radius R GC. The most metal-rich stars in the inner Galaxy are concentrated to the plane and the more metal-poor stars are found predominantly further from the plane, with an overall vertical gradient in the mean of the metallicity distribution function of about - 0.45 dex kpc-1. This vertical gradient is believed to reflect the changing contribution with height of different populations in the innermost region of the Galaxy. The more metal-rich stars of the bulge are part of the boxy/peanut structure and comprise stars in orbits which trace out the underlying X-shape. There is still a lack of consensus on the origin of the metal-poor stars ([Fe/H] < -0.5) in the region of the bulge. Some studies attribute the more metal-poor stars of the bulge to the thick disk and stellar halo that are present in the inner region, and other studies propose that the metal-poor stars are a distinct `old spheroid' bulge population. Understanding the origin of the populations that make up the metallicity distribution function of the bulge, and identifying if there is a unique bulge population which has formed separately from the disk and halo, has important consequences for identifying the relevant processes in the formation and evolution of the Milky Way.

  16. Metal hybrid nanoparticles for catalytic organic and photochemical transformations.

    PubMed

    Song, Hyunjoon

    2015-03-17

    In order to understand heterogeneous catalytic reactions, model catalysts such as a single crystalline surface have been widely studied for many decades. However, catalytic systems that actually advance the reactions are three-dimensional and commonly have multiple components including active metal nanoparticles and metal oxide supports. On the other hand, as nanochemistry has rapidly been developed and been applied to various fields, many researchers have begun to discuss the impact of nanochemistry on heterogeneous catalysis. Metal hybrid nanoparticles bearing multiple components are structurally very close to the actual catalysts, and their uniform and controllable morphology is suitable for investigating the relationship between the structure and the catalytic properties in detail. In this Account, we introduce four typical structures of metal hybrid nanoparticles that can be used to conduct catalytic organic and photochemical reactions. Metal@silica (or metal oxide) yolk-shell nanoparticles, in which metal cores exist in internal voids surrounded by thin silica (or metal oxide) shells, exhibited extremely high thermal and chemical stability due to the geometrical protection of the silica layers against the metal cores. The morphology of the metal cores and the pore density of the hollow shells were precisely adjusted to optimize the reaction activity and diffusion rates of the reactants. Metal@metal oxide core-shell nanoparticles and inverted structures, where the cores supported the shells serving an active surface, exhibited high activity with no diffusion barriers for the reactants and products. These nanostructures were used as effective catalysts for various organic and gas-phase reactions, including hydrogen transfer, Suzuki coupling, and steam methane reforming. In contrast to the yolk- and core-shell structures, an asymmetric arrangement of distinct domains generated acentric dumbbells and tipped rods. A large domain of each component added multiple

  17. Contamination of the transformer oil of power transformers and shunting reactors by metal-containing colloidal particles

    SciTech Connect

    L'vov, S. Yu.; Komarov, V. B.; Bondareva, V. N.; Seliverstov, A. F.; Lyut'ko, E. O.; L'vov, Yu. N.; Ershov, B. G.

    2011-05-15

    The results of a measurement of the contamination of the oil in 66 transformers by metal-containing colloidal particles, formed as a result of the interaction of the oil with the structural materials (the copper of the windings, the iron of the tank and core etc.), and also the results of measurements of the optical turbidity of the oil in 136 transformers when they were examined at the Power Engineering Research and Development Center Company are presented. Methods of determining the concentration of copper and iron in transformer oil are considered. The limiting values of the optical turbidity factors, the copper and iron content are determined. These can serve as a basis for taking decisions on whether to replace the silica gel of the filters for continuously purifying the oil of power transformers and the shunting reactors in addition to the standardized oil contamination factors, namely, the dielectric loss tangent and the acidity number of the oil.

  18. Local Field Distribution Function and High Order Field Moments for metal-dielectric composites.

    NASA Astrophysics Data System (ADS)

    Genov, Dentcho A.; Sarychev, Andrey K.; Shalaev, Vladimir M.

    2001-11-01

    In a span of two decades the physics of nonlinear optics saw vast improvement in our understanding of optical properties for various inhomogeneous mediums. One such medium is the metal-dielectric composite, where the metal inclusions have a surface coverage fraction of p, while the rest (1-p) is assumed to represent the dielectric host. The computations carried out by using different theoretical models and the experimental data show existence of giant local electric and magnetic field fluctuations. In this presentation we will introduce a new developed 2D model that determines exactly the Local Field Distribution Function (LFDF) and all other relevant parameters of the film. The LFDF for small filling factors will be shown to transform from lognormal distribution into a single-dipole distribution function. We also will confirm the predictions of the scaling theory for the high field moments, which have a power law dependence on the loss factor.

  19. Microstructural transformations in stress relieved type 316 stainless steel weld metal

    SciTech Connect

    Slattery, G.F.; O'Riordan, P.

    1980-02-01

    The heat treatment of Type 316L weld metal containing small amounts of ferrite results in the transformation of the ferrite to chi or ..cap alpha.. phases after aging for only 3 hr at 850/sup 0/C. The chi-phase transformation is associated with a transitional M/sub 23/C/sub 6/ carbide, whereas the sigma-phase transforms directly from the ferrite.

  20. Recent advances in chiral imino-containing ligands for metal-catalyzed asymmetric transformations.

    PubMed

    Chen, Xu; Lu, Zhan

    2017-03-21

    In this review, the recent applications of a variety of chiral imino-containing ligands classified by different types of metal-catalyzed asymmetric reactions are summarized. The progress made in this area would encourage us to design and synthesize more novel chiral imino-containing ligands, and explore their applications in metal-catalyzed asymmetric transformations.

  1. Touch and step potential analysis at 23.9kV to 4.16kV & 13.8kV to 4.16kV distribution substations with pad-mounted transformers, floating grounds, and other exposed ungrounded metal bodies using WinIGS

    NASA Astrophysics Data System (ADS)

    Guzman, David G.

    An electrical substation is composed of various subsystems that allow for the effective and safe operation of the power grid. One of the subsystems integrating a conventional substation is defined as the ground grid system. This system allows for the effective operation of the power grid and all the electrical equipment connected to it by providing a ground potential reference, commonly known as the system ground. In addition, the ground grid system provides safety to the workers and the public transiting inside or living nearby a substation by reducing the step and touch potential (or voltage) levels present during a system fault. In today's utility industry practices there is an increasing trend for using pad-mounted electrical equipment for substation applications in an effort to construct new or upgrade existing electrical facilities inside limited property spaces. This thesis work presents an analysis for the effects of touch and step voltages at existing distribution substations where 23.9kV to 4.16kV & 13.8kV to 4.16kV pad-mounted transformers and other pad-mounted switchgear was installed to replace the traditional station class equipment. Moreover, this study will expose modeling techniques employed to define and determine the effects of floating grounds and other exposed metal bodies inside or surrounding these substations using WinIGS; this is in an effort to determine any risks of electric shock associated with this type of installations. The results presented in this work are intended to verify the requirements for the ground grid analysis and design for 4.16kV distribution substations with pad-mounted equipment in order to prevent dangerous step and touch voltage levels appearing at these sites during system faults; and ultimately prevent exposing individuals to the risk of an electric shock.

  2. Estimation of heavy metal transformations in municipal solid waste.

    PubMed

    Flyhammar, P

    1997-05-30

    The behaviour of heavy metals bound to municipal solid waste (MSW) and exposed to 2 decades of anaerobic waste stabilization processes have been estimated. Heavy metal solid forms in a waste degradation residue have been compared with a reconstructed waste similar to that initially disposed of in 1973. The initial waste was composed of a mixture of shredded MSW (95% dry wt.) and anaerobic sewage sludge (5% dry wt.). A sequential chemical extraction method has been used to fractionate the heavy metals into five categories of available and reactive solid forms. The results imply that these forms can be ascribed to approximately 30% of the total content of the heavy metals in the degraded waste and the portion of heavy metals bound to oxidizable solid forms seems to be higher in the degraded than the fresh MSW. The bulk of the remaining heavy metals are assumed to be less available and bound into resistant lattice structures, such as metal and polymer items. A comparison between fractionation patterns of the waste in this study and of a few sediments collected from different environments imply similarities between the fresh MSW and an oxic sediment from one site and the sewage sludge and anoxic sediments from another site. Fractionation patterns of the degraded waste are found to be quite similar to those of the anoxic sediments, except for Pb, Ni and Cd which are more similar to fresh MSW.

  3. Distribution of metal and adsorbed guest species in zeolites

    SciTech Connect

    Chmelka, B.F.

    1989-12-01

    Because of their high internal surface areas and molecular-size cavity dimensions, zeolites are used widely as catalysts, shape- selective supports, or adsorbents in a variety of important chemical processes. For metal-catalyzed reactions, active metal species must be dispersed to sites within the zeolite pores that are accessible to diffusing reactant molecules. The distribution of the metal, together with transport and adsorption of reactant molecules in zeolite powders, are crucial to ultimate catalyst performance. The nature of the metal or adsorbed guest distribution is known, however, to be dramatically dependent upon preparatory conditions. Our objective is to understand, at the molecular level, how preparatory treatments influence the distribution of guest species in zeolites, in order that macroscopic adsorption and reaction properties of these materials may be better understood. The sensitivity of xenon to its adsorption environment makes {sup 129}Xe NMR spectroscopy an important diagnostic probe of metal clustering and adsorbate distribution processes in zeolites. The utility of {sup 129}Xe NMR depends on the mobility of the xenon atoms within the zeolite-guest system, together with the length scale of the sample heterogeneity being studied. In large pore zeolites containing dispersed guest species, such as Pt--NaY, {sup 129}Xe NMR is insensitive to fine structural details at room temperature.

  4. Neoplastic transformation of cells by soluble but not particulate forms of metals used in orthopaedic implants.

    PubMed

    Doran, A; Law, F C; Allen, M J; Rushton, N

    1998-01-01

    Recent developments in cell culture techniques have made it possible to study the cellular mechanisms involved in carcinogenesis and to apply these methods as screening tools in vitro. This study investigated and compared the ability of the metals most commonly used in orthopedic implants to induce toxicity and neoplastic transformation in the C3H10T1/2 mouse fibroblast cell line. Eight metals (cobalt, chromium, nickel, iron, molybdenum, aluminium, vanadium and titanium) and their alloys (stainless steel, cobalt-chrome alloy and titanium alloy) were tested, both as soluble salts and as solid particles. There were marked differences between the various metals in terms of both toxicity and transforming ability. Significant increases in the incidence of cell transformation were seen with soluble forms of cobalt, chromium, nickel and molybdenum but not with iron, aluminium, vanadium or titanium. For most of the metals. transforming ability was directly related to toxicity, although this correlation did not hold for either molybdenum or vanadium. The physical form of the metal was critically important in determining its effects, and transformation occurred only with soluble metal salts.

  5. Redshift distribution of Lyα lines and metal systems

    NASA Astrophysics Data System (ADS)

    Demiański, M.; Doroshkevich, A. G.; Turchaninov, V.

    2000-11-01

    The observed redshift distribution of Lyα lines and metal systems is examined in order to discriminate and to trace the evolution of structure elements observed in the galaxy distribution, at small redshifts, and to test the theoretical description of structure evolution. We show that the expected evolution of a filamentary component of structure describes quite well the redshift distribution of metal systems and stronger Lyα lines with log(NHi)>=14, at z<=3. The redshift distribution of weaker Lyα lines can be attributed to the population of poorer structure elements (Zel'dovich pancakes), which were formed at high redshifts from the invisible dark matter and non-luminous baryonic matter, and which at lower redshifts are mainly merged and dispersed.

  6. [Transition metal mediated transformations of small molecules]. Progress report

    SciTech Connect

    Sen, A.

    1992-10-01

    Work on organotransition metal chemistry, homogeneous and heterogeneous catalysis is summarized. Several cationic palladium(II) complexes with bulky phosphine or pyridine ligands were discovered that are highly selective catalysts for linear dimerization of vinyl monomers and linear polymerization of p-divinylbenzene, the reactions proceeding through a carbocationic mechanism. Our studies were continued on alternating olefin-carbon monoxide copolymers. The copolymerization reaction and reactivity of copolymers were examined. New catalytic systems for alternating copolymerization of {alpha}-olefins with CO were discovered. In the case of styrene derivatives, tactic copolymers were obtained. Poly(ethylenepyrrolediyl) derivatives were synthesized from alternating ethylene-carbon monoxide copolymer and become electronic conductors when doped with iodine. A catalytic system for direct synthesis of polyureas and polyoxamides from and diamines was also discovered. Pt metal catalyzed the oxidation of ethers, esters, and amines to carboxylic acids and the oxidation of olefins to 1,2-diols. Anaerobic and aerobic decomposition of molybdenum(VI)-oxoalkyl compounds were studied for heterogeneous oxidation of alkanes and olefins on Mo(VI)-oxide surfaces. Synthesis of polymer-trapped metal, metal oxide, and metal sulfide nanoclusters (size <1--10 nm) was studied.

  7. 77 FR 32916 - Energy Conservation Standards for Distribution Transformers: Public Meeting and Availability of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-04

    ... Transformers: Public Meeting and Availability of Supplementary Analysis AGENCY: Office of Energy Efficiency and... additional information that it is making available about the liquid-immersed distribution transformer... transformers. In addition to this notice and the public meeting, DOE has several documents and analytical...

  8. The feasibility of replacing or upgrading utility distribution transformers during routine maintenance

    SciTech Connect

    Barnes, P.R.; Van Dyke, J.W.; McConnell, B.W.; Cohn, S.M.; Purucker, S.L.

    1995-04-01

    It is estimated that electric utilities use about 40 million distribution transformers in supplying electricity to customers in the United States. Although utility distribution transformers collectively have a high average efficiency, they account for approximately 61 billion kWh of the 229 billion kWh of energy lost annually in the delivery of electricity. Distribution transformers are being replaced over time by new, more efficient, lower-loss units during routine utility maintenance of power distribution systems. Maintenance is typically not performed on units in service. However, units removed from service with appreciable remaining life are often refurbished and returned to stock. Distribution transformers may be removed from service for many reasons, including failure, over- or underloading, or line upgrades such as voltage changes or rerouting. When distribution transformers are removed from service, a decision must be made whether to dispose of the transformer and purchase a lower-loss replacement or to refurbish the transformer and return it to stock for future use. This report contains findings and recommendations on replacing utility distribution transformers during routine maintenance, which is required by section 124(c) of the Energy Policy Act of 1992. The objectives of the study are to evaluate the practicability, cost-effectiveness, and potential energy savings of replacing or upgrading existing transformers during routine utility maintenance and to develop recommendations on was to achieve the potential energy savings.

  9. Heavy metal distribution in sediments from Calabar River, southeastern Nigeria

    NASA Astrophysics Data System (ADS)

    Ntekim, E. E. U.; Ekwere, S. J.; Ukpong, E. E.

    1993-08-01

    The concentration and areal distribution of selected metals (Pb, Zn, Cu, Cd, Ni, Fe, and Cr) in the sediments of the Calabar River were studied to determine the extent of anthropogenic input and to estimate the effects of dumping industrial waste materials into the river. The concentrations of Pb, Zn, and Cu indicate relatively moderate pollution mainly on the left-hand side of the river while Ni, Cr, Co, Cd, and Fe levels are below values found to have adverse effects on the lives of marine biota. High metal contents are found close to industrial establishments and so enhanced metal concentrations are related to industrial sewage and metal leaching from garbage and solid waste dumps.

  10. Heavy metal distribution in sediments from Calabar River, southeastern Nigeria

    SciTech Connect

    Ntekim, E.E.U.; Ekwere, S.J.; Ukpong, E.E.

    1993-08-01

    The concentration and areal distribution of selected metals (Pb, Zn, Cu, Cd, Ni, Fe, and Cr) in the sediments of the Calabar River were studied to determine the extent of anthropogenic input and to estimate the effects of dumping industrial waste materials into the river. The concentrations of Pb, Zn, and Cu indicate relatively moderate pollution mainly on the left-hand side of the river while Ni, Cr, Co, Cd, and Fe levels are below values found to have adverse effects on the lives of marine biota. High metal contents are found close to industrial establishments and so enhanced metal concentrations are related to industrial sewage and metal leaching from garbage and solid waste dumps. 15 refs., 6 figs., 5 tabs.

  11. Variations of metal distribution in sewage sludge composting.

    PubMed

    Nomeda, Sabiene; Valdas, Paulauskas; Chen, Shen-Yi; Lin, Jih-Gaw

    2008-01-01

    In the study, the variations of heavy metal distributions (of Cu, Mn, Pb, and Zn) during the sewage sludge composting process were investigated by sequential extraction procedures. The total content of Cu and Zn in the composted mixture increased after the composting process. Mn and Zn were mainly found in mobile fractions (exchangeable fraction (F1), carbonate fraction (F2), and Fe/Mn oxide fraction (F3)). Cu and Pb were strongly associated with the stable fractions (organic matter/sulfides fraction (F4) and residual fraction (F5)). These five metal fractions were used to calculate the metal mobility (bioavailability) in the sewage sludge and composted mixture. The mobility (bioavailability) of Mn, Pb, and Zn (but not Cu) increased during the composting process. The metal mobility in the composted mixture ranked in the following order: Mn>Zn>Pb>Cu.

  12. 10 CFR 431.193 - Test procedures for measuring energy consumption of distribution transformers.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 10 Energy 3 2010-01-01 2010-01-01 false Test procedures for measuring energy consumption of distribution transformers. 431.193 Section 431.193 Energy DEPARTMENT OF ENERGY ENERGY CONSERVATION ENERGY... § 431.193 Test procedures for measuring energy consumption of distribution transformers. The test...

  13. Elucidating the Composition and Distribution of Trace Metals in Corals

    NASA Astrophysics Data System (ADS)

    Farfan, G.; Webb, S. M.; Apprill, A.; Hansel, C. M.

    2014-12-01

    Coral reefs host a plethora of marine life and thereby provide a wealth of aesthetic and economic benefits to coastal countries. Anthropogenic influences, including local coastal water contamination, however threaten the health of these delicate ecosystems. Metal incorporation into carbonate minerals, the backbone of coral reefs, is known to have a large yet variable impact on carbonate structure and solubility. Yet, trace metal influences on the structure, porosity, composition, and solubility of coral skeletons is largely unknown. Here, we coupled synchrotron-based micro-X-ray fluorescence (u-XRF) mapping and X-ray absorption near edge structure (XANES) spectroscopy with micro-X-ray diffraction (XRD) to explore the distribution and speciation of trace metals associated with corals and their impact on the carbonate structure of corals obtained from reefs varying in anthropogenic influence - Florida Keys, FL USA and the Federated States of Micronesia. Iron and copper were the most abundant metals in the biological tissue, while in some areas zinc was observed in the tissue, overlapping with the skeleton. Trace metals were not detectable in the aragonite skeletons; in fact, the distributions of Ca and Fe were anti-correlated. XANES spectra show that the iron is primarily Fe(III), likely as the poorly crystalline iron oxide ferrihydrite structure or trapped within ferretin proteins. The same trace metals were observed in corals of different species and from different environments. This in situ investigation corroborates previous studies that corals tend to incorporate iron into the biological components but not into the aragonite skeleton. Given the dominant partitioning of metals within the biological tissue rather than the coral skeleton, the specific carbon molecules responsible for metal attenuation and their fate under changing geochemical conditions and following coral death require exploration.

  14. Inhomogeneous composition distribution in monolayer transition metal dichalcogenide alloys

    NASA Astrophysics Data System (ADS)

    Xie, Shuang; Xu, Mingsheng; Huang, Shuyun; Liang, Tao; Wang, Shengping; Li, Hongfei; Iwai, Hideo; Onishi, Keiko; Hanagata, Nobutaka; Fujita, Daisuke; Ma, Xiangyang; Yang, Deren

    2017-04-01

    Alloying with various compositions is an efficient method to tailor the optoelectronic properties of two-dimensional (2D) transition metal dichalcogenides (TMDs). However, the composition distribution in the monolayer of TMDs alloys lacks detailed investigation. Here, by exploring scanning Auger electron spectroscopy, we investigate the composition distribution in MoS2(1-x)Se2x monolayers with high spatial resolution. Our results demonstrate that inhomogeneous composition distribution exists not only among different nanosheets on a substrate but also within individual nanosheets. Our study would be helpful to develop new methods for controllable synthesis of TMDs alloys and other 2D materials.

  15. 25-KVA Amorphous Metal-Core Transformer Developmental Test Report

    DTIC Science & Technology

    1989-08-01

    after the DROP TEST. Tests were also performed in the Dev. Lab . Results S/N P217061 S/N P265882 S/N P265885 1.Elect.* Factry Test Lab Test Factry Test...10 RESULTS AND CONCLUSIONS ........ ..................... .. 11 Phase I .......... ........................... . 11 Phase II...characteorist ics of tleo trins formers cilan1ged as a result , of the tests. * Pass/Fail Criteria: Thin transformers had to pass tile commercial

  16. Characterisation and distribution of heavy metals at Masaya volcano, Nicaragua

    NASA Astrophysics Data System (ADS)

    Hinrichs, M.; Rymer, H.; Gillman, M.; Blake, S.

    2011-12-01

    Activity at Masaya volcano, Nicaragua, is characterised by periodic cycles of intense gas emission that last years to decades. The volcano entered its current phase of degassing in 1993, which resulted in a low-level persistent gas plume. As a result of this continuous emission, the substantial deposition of heavy metals onto the surrounding soils (andosols) is thought to be occurring (Delfosse et al., 2003). The deposition of these heavy metal plume components, and their incorporation into soil, is of key interest because once discharged to the environment they accumulate throughout the food chain and may pose a serious ecological threat (Alloway, 1995). Although many studies have focused on the impacts of volcanic gases on the environment, few have addressed the fate of the metals released by persistent gas plumes. This study therefore investigates the patterns of heavy metal transport, deposition and distribution at Masaya in order to provide additional information on the processes that govern the behaviour of volcanic heavy metals. A number of agricultural and non-agricultural soils at two horizons (A: 0-10 cm and B: 20-30 cm) were collected and their trace metal content analysed. Twenty sites were sampled from the active vent to ~5 km downwind, as well as two control sites upwind of the volcano. Preliminary data suggest that a rapid deposition of metals occurs close to the source, with metal concentrations in the soil generally decreasing with distance away from the active vent. Cr and As clearly follow this trend, with maximum concentrations of 20.71 and 7.61 mg/kg respectively occurring closest to the vent. Concentration peaks for Mn, Co, Ni, Cu, and Zn (959.30, 21.57, 13.44, 152.85, and 72.73 mg/kg respectively) occur slightly further away from the vent, implying that these metals are transported further. The concentration of Cr, Co, Al, Ni and Mn was found to increase from soil horizon A to B, whereas the abundance of Zn decreases with depth. Heavy metal

  17. Hydrated lime for metals immobilization and explosives transformation: Treatability study.

    PubMed

    Martin, W Andy; Larson, S L; Nestler, C C; Fabian, G; O'Connor, G; Felt, D R

    2012-05-15

    Fragmentation grenades contain Composition B (RDX and TNT) within a steel shell casing. There is the potential for off-site migration of high explosives and metals from hand grenade training ranges by transport in surface water and subsurface transport in leachate. This treatability study used bench-scale columns and mesocosm-scale laboratory lysimeters to investigate the potential of hydrated lime as a soil amendment for in situ remediation of explosives and metals stabilization in hand grenade range soils. Compared to the unamended soil there was a 26-92% reduction of RDX in the leachate and runoff water from the lime treated soils and a 66-83% reduction of zinc in the leachate and runoff water samples; where the hand grenade range metals of concern were zinc, iron, and manganese. The amended soil was maintained at the target pH of greater than 10.5 for optimum explosives decomposition. The treatability study indicated a high potential of success for scale-up to an in situ field study.

  18. Metal electrode integration on macroporous silicon: pore distribution and morphology

    PubMed Central

    2012-01-01

    In this work, a new approach for the one-step integration of interdigitated electrodes on macroporous silicon substrates is presented. Titanium/gold interdigitated electrodes are used to pattern p-type silicon substrates prior the anodization in an organic electrolyte. The electrolyte characteristics, conductivity, and pH have been found to affect the adherence of the metal layer on the silicon surface during the electrochemical etching. The impact of the metal pattern on size distribution and morphology of the resulting macroporous silicon layer is analyzed. A formation mechanism supported by finite element simulation is proposed. PMID:22799456

  19. Fourier Transform Microwave Spectroscopy of Alkali Metal Hydrosulfides: Detection of Ksh

    NASA Astrophysics Data System (ADS)

    Sheridan, P. M.; Binns, M. K. L.; Young, J. P.; Bucchino, M. P.; Ziurys, L. M.

    2012-06-01

    Fourier transform microwave (FTMW) techniques have been used to record pure rotational spectra of potassium hydrosulfide and its deuterium isotopologue in their ground electronic states. This study represents the first gas phase spectroscopic observation of KSH. FTMW spectra of NaSH were also recorded. The metal hydrosulfides were produced by discharge assisted laser ablation of the solid alkali metal in the presence of hydrogen sulfide or deuterated hydrogen sulfide. Rotational transitions in the 5-20 GHz range were measured and hyperfine splittings due to the alkali metals and deuterium were resolved. Rotational as well as metal and deuterium quadrupole coupling constants have been determined from the data. The hyperfine parameters will be interpreted in terms of metal-ligand bonding character. Geometric parameters of the alkali metal hydrosulfides will be compared.

  20. The migration and transformation behaviors of heavy metals during the hydrothermal treatment of sewage sludge.

    PubMed

    Huang, Hua-Jun; Yuan, Xing-Zhong

    2016-01-01

    Various hydrothermal treatment methods, including hydrothermal carbonization, liquefaction and sub/super-critical water gasification, have been applied to the disposal of sewage sludge for producing bio-materials or bio-fuels. It has become a research hotspot whether the heavy metals contained in sewage sludge can be well treated/stabilized after the hydrothermal treatments. This review firstly summarized the methods of assessing heavy metals' contamination level/risk and then discussed the migration and transformation behaviors of heavy metals from the following aspects: the effect of reaction temperature, the effect of additives (catalysts and other biomass), the effect of the type of solvent and the effect of reaction time. This review can provide an important reference for the further study of the migration and transformation behaviors of heavy metals during the hydrothermal treatment of sewage sludge. Copyright © 2015 Elsevier Ltd. All rights reserved.

  1. Distribution of heavy metals from flue gas in algal bioreactor

    NASA Astrophysics Data System (ADS)

    Napan, Katerine

    Flue gas from coal-fired power plants is a major source of CO2 to the atmosphere. Microalgae can use this enriched form of CO2 as carbon source and in turn the biomass can be used to produce food, feed, fertilizer and biofuels. However, along with CO2, coal-based flue gas will inevitably introduce heavy metals, which have a high affinity to bind algal cells, could be toxic to the organisms and if transferred to the products could limit their uses. This study seeks to address the distribution and impact of heavy metals present in flue gas on microalgae production systems. To comprehend its effects, algae Scenedesmus obliquus was grown in batch reactors in a multimetal system. Ten heavy metals (Cu, Co, Zn, Pb, As, Se, Cr, Hg, Ni and Cd) were selected and were evaluated at four concentrations (1X, 2X, 5X and 10X). Results show that most heavy metals accumulated mainly in biomass and were found in very low concentrations in media. Hg was shown to be lost from the culture, with low amounts present in the biomass. An upper limit for As uptake was observed, suggesting its likelihood to build-up in the system during medium recycle. The As limited bioaccumulation was overcome by addition of sulfur to the algal medium. Heavy metal at 2X, 5X and 10X inhibited both growth and lipid production, while at the reference concentration both biomass and lipids yields were increased. Heavy metal concentrations in the medium and biomass were time dependent, and at the end of the cultivation most heavy metals in the supernatant solution complied with the recommendations for irrigation water, while biomass was below limits for cattle and poultry feed, fertilizer, plastic and paper. This research shows that bioremediation of CO2 and heavy metals in combination with energy production can be integrated, which is an environmentally friendly form of biotechnology.

  2. Transformation of metals speciation in a combined landfill leachate treatment.

    PubMed

    Wu, Yanyu; Zhou, Shaoqi; Chen, Dongyu; Zhao, Rong; Li, Huosheng; Lin, Yiming

    2011-04-01

    Landfill leachate was treated by a combined sequential batch reactor (SBR), coagulation, Fenton oxidation and biological aerated filter (BAF) technology. The metals in treatment process were fractionated into three fractions: particulate and colloidal (size charge filtration), free ion/labile (cation exchange) and non-labile fractions. Fifty percent to 66% Cu, Ni, Zn, Mn, Pb and Cd were present as particulate/colloidal matter in raw leachate, whereas Cr was present 94.9% as non-labile complexes. The free ion/labile fractions of Ni, Zn, Mg, Mn, Pb and Cd increased significantly after treatment except Cr. Fifty-nine percent to 100% of Al was present mainly as particulate/colloidal matter >0.45 μm and the remaining portions were predicted as non-labile complexes except in coagulation effluent. The speciation of Fe varied significantly in various individual processes. Visual MINTEQ simulation showed that 95-100% colloidal species for Cu, Cd and Pb were present as metal-humic complexes even with the lower dissolved organic carbon. Optimum agreements for the free ion/labile species were within acidic solution, whereas under-estimated in alkaline effluents. Overestimated particulate/colloidal fraction consisted with the hypothesis that a portion of colloids in fraction <0.45 μm were considered as dissolved.

  3. Catalytic and photocatalytic transformations on metal nanoparticles with targeted geometric and plasmonic properties.

    PubMed

    Linic, Suljo; Christopher, Phillip; Xin, Hongliang; Marimuthu, Andiappan

    2013-08-20

    Heterogeneous catalysis by metals was among the first enabling technologies that extensively relied on nanoscience. The early intersections of catalysis and nanoscience focused on the synthesis of catalytic materials with high surface to volume ratio. These synthesis strategies mainly involved the impregnation of metal salts on high surface area supports. This would usually yield quasi-spherical nanoparticles capped by low-energy surface facets, typically with closely packed metal atoms. These high density areas often function as the catalytically active surface sites. Unfortunately, strategies to control the functioning surface facet (i.e., the geometry of active sites that performs catalytic turnover) are rare and represent a significant challenge in our ability to fine-tune and optimize the reactive surfaces. Through recent developments in colloidal chemistry, chemists have been able to synthesize metallic nanoparticles of both targeted size and desired shape. This has opened new possibilities for the design of heterogeneous catalytic materials, since metal nanoparticles of different shapes are terminated with different surface facets. By controlling the surface facet exposed to reactants, we can start affecting the chemical transformations taking place on the metal particles and changing the outcome of catalytic processes. Controlling the size and shape of metal nanoparticles also allows us to control the optical properties of these materials. For example, noble metals nanoparticles (Au, Ag, Cu) interact with UV-vis light through an excitation of localized surface plasmon resonance (LSPR), which is highly sensitive to the size and shape of the nanostructures. This excitation is accompanied by the creation of short-lived energetic electrons on the surface of the nanostructure. We showed recently that these energetic electrons could drive photocatalytic transformations on these nanostructures. The photocatalytic, electron-driven processes on metal nanoparticles

  4. Model of bidirectional reflectance distribution function for metallic materials

    NASA Astrophysics Data System (ADS)

    Wang, Kai; Zhu, Jing-Ping; Liu, Hong; Hou, Xun

    2016-09-01

    Based on the three-component assumption that the reflection is divided into specular reflection, directional diffuse reflection, and ideal diffuse reflection, a bidirectional reflectance distribution function (BRDF) model of metallic materials is presented. Compared with the two-component assumption that the reflection is composed of specular reflection and diffuse reflection, the three-component assumption divides the diffuse reflection into directional diffuse and ideal diffuse reflection. This model effectively resolves the problem that constant diffuse reflection leads to considerable error for metallic materials. Simulation and measurement results validate that this three-component BRDF model can improve the modeling accuracy significantly and describe the reflection properties in the hemisphere space precisely for the metallic materials.

  5. Magnetic flux distribution in the amorphous modular transformers

    NASA Astrophysics Data System (ADS)

    Tomczuk, B.; Koteras, D.

    2011-06-01

    3D magnetic fluxes in one-phase and three-phase transformers with amorphous modular cores have been studied. Scalar potentials were implemented for the 3D Finite Element field calculation. Due to the inability to simulate each thin amorphous layer, we introduced supplementary permeabilities along the main directions of magnetization. The calculated fluxes in the cores were tested on the prototypes.

  6. The Radon cumulative distribution transform and its application to image classification

    PubMed Central

    Kolouri, Soheil; Park, Se Rim; Rohde, Gustavo K.

    2016-01-01

    Invertible image representation methods (transforms) are routinely employed as low-level image processing operations based on which feature extraction and recognition algorithms are developed. Most transforms in current use (e.g. Fourier, Wavelet, etc.) are linear transforms, and, by themselves, are unable to substantially simplify the representation of image classes for classification. Here we describe a nonlinear, invertible, low-level image processing transform based on combining the well known Radon transform for image data, and the 1D Cumulative Distribution Transform proposed earlier. We describe a few of the properties of this new transform, and with both theoretical and experimental results show that it can often render certain problems linearly separable in transform space. PMID:26685245

  7. The Radon Cumulative Distribution Transform and Its Application to Image Classification.

    PubMed

    Kolouri, Soheil; Park, Se Rim; Rohde, Gustavo K

    2016-02-01

    Invertible image representation methods (transforms) are routinely employed as low-level image processing operations based on which feature extraction and recognition algorithms are developed. Most transforms in current use (e.g., Fourier, wavelet, and so on) are linear transforms and, by themselves, are unable to substantially simplify the representation of image classes for classification. Here, we describe a nonlinear, invertible, low-level image processing transform based on combining the well-known Radon transform for image data, and the 1D cumulative distribution transform proposed earlier. We describe a few of the properties of this new transform, and with both theoretical and experimental results show that it can often render certain problems linearly separable in a transform space.

  8. A metal mixture induces transformation upon antioxidant depletion in a hepatic cell line.

    PubMed

    Sánchez-Valle, Vicente; Valverde, Mahara; Carrizale, Leticia; Mejía, Jesus; Zepeta, Nahum; Rojas, Emilio

    2013-01-01

    Metals are ubiquitous soil, air, and water pollutants. A mixture of arsenic cadmium and lead, in particular, has commonly been found in the vicinity of smelter areas. The mixture of As-Cd-Pb has been shown to be carcinogenic, and transforming potential and oxidative stress have been proposed as principal mechanisms involved in this process. The aim of this work was to explore the role of the antioxidant barrier in the establishment of cell transformation upon chronic exposure to a metal mixture containing 2 μM NaAsO(2), 2 μM. CdCl(2), and 5 μM Pb(C(2)H(3)O(2))(2)∙3H(2)O in WRL-68 cells-a non-transformed human hepatic cell line. In this study, we used a WRL-68 cell model of human embryonic hepatic origin treated with antioxidant inhibitors (L-Buthionine-sulfoxamine and aminotriazole) to test the role of the antioxidant barrier in the establishment of cell transformation upon chronic exposure to a metal mixture of As-Cd-Pb (2 μM NaAsO(2), 2 μM CdCl(2) and 5 μM Pb(C(2)H(3)O(2))(2)∙3H(2)O). We evaluated oxidative damage markers, including reactive oxygen species, lipid peroxidation, and genotoxicity, as well as antioxidant response markers, including glutathione concentration, catalase activity, and superoxide dismutase activity, which promote morphological transformation, which can be quantified by foci formation. As expected, we found an increase in the intracellular concentration of the metals after treatment with the metal mixture. In addition, treatment with the metal mixture in addition to inhibitors resulted in a large increase in the intracellular concentration of cadmium and lead. Our results describe the generation of reactive oxygen species, cytotoxicity, genotoxicity, and oxidative damage to macromolecules that occurred exclusively in cells that were morphologically transformed upon exposure to a metal mixture and antioxidant barrier inhibition. Our results show the importance of the antioxidant barrier role in the protection of cellular integrity

  9. Particulate metal distribution in Guadiana estuary punctuated by flood episodes

    NASA Astrophysics Data System (ADS)

    Caetano, Miguel; Vale, Carlos; Falcão, Manuela

    2006-10-01

    The distribution of major (Al, Ca, Mg, Fe and Mn) and trace metals (Zn, Cu, Pb and Cd) in particulate material was determined in different flow and tidal conditions along the Guadiana estuary. Under moderate river flows, concentrations of Al in SPM decreased seawards, while Ca and Mg showed an opposite trend reflecting the physical mixing of fluvial and marine particles along the salinity gradient. Ratios of Cu/Al, Zn/Al, Pb/Al and Cd/Al increased sharply in the estuary mouth as a result of local inputs of urban sewage from the two major cities located at the estuary mouth. Under these flow conditions Cu/Al and Cd/Al ratios were higher in spring, indicating that retention by phytoplankton was the major factor influencing these metal gradients in SPM. Sediments transported during an exceptional flood contained higher inorganic fraction and lower metal content (two orders of magnitude) than particles transported under moderate river flows. The material exported during flood peaks was recorded in the Guadiana shelf as coarser sediment layer with diminished levels of Fe, Cu and Pb. In spite of metal mobility in upper sediment layers of the coastal zone, these metals reflect the export episodes in Guadiana. The construction of Alqueva dam will attenuate in the future these flood events decreasing the amount of sediment supplied by the river to the coastal zone.

  10. Heavy metal distribution in sediment profiles of Tuul River, Mongolia

    NASA Astrophysics Data System (ADS)

    Soyol-Erdene, T. O.; Lin, S.; Tuuguu, E.; Daichaa, D.; Ulziibat, B.; Enkh-Amgalan, T.; Hsieh, I. C.

    2016-12-01

    The distribution, enrichment, and accumulation of heavy metals in the sediments of Tuul River, Mongolia were investigated. Sediment core samples with depths of 4.0-49 cm from thirteen locations along the Tuul River were collected in the period from Sept. 2013 to Aug. 2014 and characterized for metal contents (e.g., Al, Fe, Cu, Zn, Pb, Ni, Cd, Hg and Cr), water content, and grain size. Results showed that metal average concentrations in the sample cores varied from 0.02 mg kg-1 for Hg (0.01 - 0.03 mg kg-1) to 481 mg kg-1 for Mn (277 - 623 mg kg-1). Metal concentrations at the downstream of the capital city were higher than those at other locations. All heavy metals studied, had average enrichment factors less than 3.0, but some sites had relatively higher values of enrichment factors up to 18 for Cu, 4.1 for Hg, 5.9 for Zn, and 25 for Cr, especially at middle depth ( 8-12 cm) of the cores. Importantly, severe pollution of mercury (Hg) was found at the downstream of the capital city which requires immediate remediation before this metal propagates into the food chain. Metal concentrations correlated to the physical-chemical properties of the sediments, which suggested the influence of industrial and municipal wastewaters discharged from the nearby cities. Results of this work would help to develop strategy to remediate of Tuul river sediment and to reduce the exposure of inhabitants to toxic substances.

  11. Higher-order transformation and the distributed data problem.

    SciTech Connect

    Winter, Victor Lono; Subramaniam, Mahadevan

    2003-12-01

    The distributed data problem, is characterized by the desire to bring together semantically related data from syntactically unrelated portions of a term. Two strategic combinators, dynamic and transient, are introduced in the context of a classical strategic programming framework. The impact of the resulting system on instances of the distributed data problem is then explored.

  12. Sustainment Transformation: Achieving a Revolution in Distribution Based Logistics

    DTIC Science & Technology

    2013-03-01

    AND ADDRESS(ES) Colonel Louis H. Jordan Jr. Strategic Research and Analysis Department 8. PERFORMING ORGANIZATION REPORT NUMBER 9...Revolution in Distribution Based Logistics by Colonel Kevin M. Powers United States Army Colonel Louis H. Jordan...Logistics DBL is an operational concept that relies on distribution velocity and precision rather than redundant supply mass… – Robert McKay & Kathy

  13. Temperature measurement inside metallic cables using distributed temperature system

    NASA Astrophysics Data System (ADS)

    Jaros, Jakub; Papes, Martin; Liner, Andrej; Vasinek, Vladimir; Mach, Veleslav; Hruby, David; Kajnar, Tomas; Perecar, Frantisek

    2015-07-01

    Nowadays, metallic cables are produced so as to avoid the maximum allowable temperature of the cable by the normal operation and the maximum allowable temperature for short-circuit the exceeding the maximum allowable internal temperature. The temperature increase is an unwanted phenomena causing losses in the cable and its abrasion. Longterm overload can lead to damaging of the cable or to the risk of fire in extreme cases. In our work, we present the temperature distribution measurement inside the metallic cables using distributed temperature system. Within the cooperation with manufacturer of the metallic cables, optical fibers were implemented into these cables. The cables are double coated and the fibers are allocated between these coatings and also in the centre of the cable. Thus we are able to measure the temperature inside the cable and also on the surface temperature along the whole cable length with spatial resolution 1 m during the cable heating. This measurement method can be also used for short-circuit prediction and detection, because this phenomena is always accompanied with temperature increase. Distributed temperature systems are already successfully implemented in temperature measurements in industry environment, such as construction, sewer systems, caliducts etc. The main advantage of these systems is electromagnetic resistance, low application price and the possibility of monitoring several kilometers long distances.

  14. Simulation of Statistical Distributions using the Memoryless Nonlinear Transform

    DTIC Science & Technology

    2011-03-01

    fact related to the Gaussian’s autocovariance by a non-linear mapping. In a practical situation we would like to specify a desired process with given...transform, and how it is imple- mented in practice . A simulator has been developed, which is fully described and docu- mented in this report. A number...problem of generating correlated clutter returns from a mathe- matical point of view, but also develops a practical mechanism for generating it

  15. The predicted metallicity distribution of stars in dwarf spheroidal galaxies

    NASA Astrophysics Data System (ADS)

    Lanfranchi, Gustavo A.; Matteucci, Francesca

    2004-07-01

    We predict the metallicity distribution of stars and the age-metallicity relation for six dwarf spheroidal (dSph) galaxies of the Local Group by means of a chemical evolution model that is able to reproduce several observed abundance ratios, and the present-day total mass and gas content of these galaxies. The model adopts up-to-date nucleosynthesis and takes into account the role played by supernovae of different types (II, Ia) allowing us to follow in detail the evolution of several chemical elements (H, D, He, C, N, O, Mg, Si, S, Ca and Fe). Each galaxy model is specified by the prescriptions of the star formation rate and by the galactic wind efficiency chosen to reproduce the main features of these galaxies. These quantities are constrained by the star formation histories of the galaxies as inferred by the observed colour-magnitude diagrams (CMD). The main conclusions are: (i) five of the six dSph galaxies are characterized by very low star formation efficiencies (ν= 0.005-0.5 Gyr-1) with only Sagittarius having a higher one (ν= 1.0 -5.0 Gyr-1) (ii) the wind rate is proportional to the star formation rate and the wind efficiency is high for all galaxies, in the range wi= 6-15 (iii) a high wind efficiency is required in order to reproduce the abundance ratios and the present-day gas mass of the galaxies; (iv) the predicted age-metallicity relation implies that the stars of the dSphs reach solar metallicities in a time-scale of the order of 2-6 Gyr, depending on the particular galaxy; (v) the metallicity distributions of stars in dSphs exhibit a peak around [Fe/H]~-1.8 to -1.5 dex, with the exception of Sagittarius, which shows a peak around [Fe/H]~-0.8 dex; (iv) the predicted metallicity distributions of stars suggest that the majority of stars in dSphs are formed in a range of metallicity in agreement with the one of the observed stars.

  16. High Pressure Phase Transformations in Heavy Rare Earth Metals and Connections to Actinide Crystal Structures

    SciTech Connect

    Vohra, Yogesh K.; Sangala, Bagvanth Reddy; Stemshorn, Andrew K.; Hope, Kevin M.

    2008-07-01

    High-pressure studies have been performed on heavy rare earth metals Terbium (Tb) to 155 GPa and Holmium (Ho) to 134 GPa in a diamond anvil cell at room temperature. The following crystal structure sequence was observed in both metals hcp {yields} Sm-type {yields} dhcp {yields} distorted fcc (hR-24) {yields} monoclinic (C2/m) with increasing pressure. The last transformation to a low symmetry monoclinic phase is accompanied by a volume collapse of 5 % for Tb at 51 GPa and a volume collapse of 3 % for Ho at 103 GPa. This volume collapse under high pressure is reminiscent of f-shell delocalization in light rare earth metal Cerium (Ce), Praseodymium (Pr), and heavy actinide metals Americium (Am) and Curium (Cm). The orthorhombic Pnma phase that has been reported in Am and Cm after f-shell delocalization is not observed in heavy rare earth metals under high pressures. (authors)

  17. Development of a Simplified Calculation Tool for Voltage Drop caused by Transformer Inrush in Distribution System

    NASA Astrophysics Data System (ADS)

    Nakachi, Yoshiki; Fukae, Takayuki; Sugahara, Toshinori; Nakamura, Hayato; Koyama, Mitsuaki; Ueda, Fukashi

    It is well known that the voltage drop due to the inrush current at energizing transformer, may at times, interrupt electrical equipment. Generally, the voltage drop is calculated by using the sophisticated tool such as EMTP, so the transformer saturation phenomenon has been properly represented. However, it is not practical for distribution system engineers to calculate the voltage drop with transformer inrush by using EMTP, because there are a lot of network access requests needing such calculations with many kinds of transformers. Therefore, in this paper, a simplified and easy-to-use calculation tool for voltage drop caused by transformer inrush in distribution system is developed. In order to grasp the voltage drop by inrush current during the planning stage, it is formulated by considering the transformer saturation/unsaturation periods in each winding type, the developed tool is based on the versatile spreadsheet software such as Microsoft Excel®. It can be used with accuracy almost similar to the EMTP.

  18. Enhanced Endosomal Escape by Light-Fueled Liquid-Metal Transformer.

    PubMed

    Lu, Yue; Lin, Yiliang; Chen, Zhaowei; Hu, Quanyin; Liu, Yang; Yu, Shuangjiang; Gao, Wei; Dickey, Michael D; Gu, Zhen

    2017-04-12

    Effective endosomal escape remains as the "holy grail" for endocytosis-based intracellular drug delivery. To date, most of the endosomal escape strategies rely on small molecules, cationic polymers, or pore-forming proteins, which are often limited by the systemic toxicity and lack of specificity. We describe here a light-fueled liquid-metal transformer for effective endosomal escape-facilitated cargo delivery via a chemical-mechanical process. The nanoscale transformer can be prepared by a simple approach of sonicating a low-toxicity liquid-metal. When coated with graphene quantum dots (GQDs), the resulting nanospheres demonstrate the ability to absorb and convert photoenergy to drive the simultaneous phase separation and morphological transformation of the inner liquid-metal core. The morphological transformation from nanospheres to hollow nanorods with a remarkable change of aspect ratio can physically disrupt the endosomal membrane to promote endosomal escape of payloads. This metal-based nanotransformer equipped with GQDs provides a new strategy for facilitating effective endosomal escape to achieve spatiotemporally controlled drug delivery with enhanced efficacy.

  19. Theory of ordering transformations in metals and minerals

    SciTech Connect

    Lindsey, T.F. . Dept. of Materials Science and Mineral Engineering Lawrence Berkeley Lab., CA )

    1991-07-01

    This dissertation presents an investigation of ordering in FCC based systems using the pair potential approximation in the ground state and mean field limits. The theoretical approach is used to explain the occurrence of observed equilibrium phases and characteristics of thermodynamic instabilities, in particular, spinodal ordering and decomposition. It is shown that the stability of non-integer domain sizes in long period superstructures such as Al{sub 3}Ti and Ag{sub 3}Mg may result from the tendency of a system to reduce the number of non-dominant ordering waves, thus producing domain sizes that have rational fraction form n/m. This conclusion is used to explain the domain size stability with respect to variations in temperature and electron concentration. The cation ordering in the precipitate phases in calcite and dolomite is analyzed by analogy with ordering in FCC based metals. The ordered phases in calcite and dolomite are shown to be consistent with pair potential minima at {l brace}100{r brace} and {l brace}1/2, 1/2, 1/2{r brace} positions in reciprocal space respectively. 32 refs., 6 figs.

  20. X-ray absorption spectroscopy (XAS) of toxic metal mineral transformations by fungi.

    PubMed

    Fomina, Marina; Charnock, John; Bowen, Andrew D; Gadd, Geoffrey M

    2007-02-01

    Fungi can be highly efficient biogeochemical agents and accumulators of soluble and particulate forms of metals. This work aims to understand some of the physico-chemical mechanisms involved in toxic metal transformations focusing on the speciation of metals accumulated by fungi and mycorrhizal associations. The amorphous state or poor crystallinity of metal complexes within biomass and relatively low metal concentrations make the determination of metal speciation in biological systems a challenging problem but this can be overcome by using synchrotron-based element-specific X-ray absorption spectroscopy (XAS) techniques. In this research, we have exposed fungi and ectomycorrhizas to a variety of copper-, zinc- and lead-containing minerals. X-ray absorption spectroscopy studies revealed that oxygen ligands (phosphate, carboxylate) played a major role in toxic metal coordination within the fungal and ectomycorrhizal biomass during the accumulation of mobilized toxic metals. Coordination of toxic metals within biomass depended on the fungal species, initial mineral composition, the nitrogen source, and the physiological state/age of the fungal mycelium.

  1. Individually Watermarked Information Distributed Scalable by Modified Transforms

    DTIC Science & Technology

    2009-10-01

    secret information in audio , video or images to known recipients are made secure by encryption. The weak part of such distribution scheme is after the...networks that are dealing with secure information such as images, video or audio these media objects can be encrypted during transmission. But such...Symposium held in Stockholm, Sweden on 19-20 October 2009 14. ABSTRACT Distribution of secret information in audio , video or images to known recipients

  2. N-14 NQR using a high-Tc rf SQUID with a normal metal transformer

    NASA Astrophysics Data System (ADS)

    He, D. F.; Tachiki, M.; Itozaki, H.

    2008-01-01

    We have improved our high-Tc SQUID-based N-14 nuclear quadrupole resonance (NQR) detection system. By using a reed relay SIL5-1A72-71L (MEDER electronic) in the normal metal transformer, the isolation to the excitation field was much improved. The high-Tc rf SQUID could operate stably when the rf excitation field was over 20 mT. By optimizing the input coil of the transformer, better sensitivity of 0.5 fT Hz-1/2 was obtained at the resonant frequency of the tuned normal metal transformer. A spin-locking spin-echo (SLSE) multi-pulse sequence was also used in the system to detect the weak NQR signals produced by samples with longer spin-spin relaxation time T2, such as trinitrotoluene (TNT).

  3. Development of a distribution transformer not subject to destructive failure--an update

    SciTech Connect

    Sokoly, T.O.; Baranowski, J.F.; Ghinazzi, J.M.; Goedde, G.L.; Porter, J.W.

    1984-09-01

    This paper reviews the application of a pancake coil winding in a 25 kVA, 15 kV class distribution transformer that is constructed using inorganic insulating materials. Techniques for designing transformers utilizing pancake coils have been developed and confirmed in full-size working models.

  4. Development of a distribution transformer that is not subject to catastrophic failure

    SciTech Connect

    Baranowski, J.F.; Goedde, G.L.

    1986-02-01

    Inorganically insulated, oil-free transformers offer potential for improving the safety of distribution systems. Laboratory tests - as well as initial results of field trials - indicate that a 25-kVA pole-mounted unit developed in this study will eliminate the rapid pressure increases that lead to catastrophic failures of conventional transformers.

  5. Analysis of failed distribution transformers and application of low voltage arresters

    SciTech Connect

    Goedde, G.L.; Plummer, C.W.

    1995-06-01

    Cooper Power Systems was contracted by EPRI in 1987 to perform a feasibility study on reducing distribution transformer basic insulation level. The project goal was to examine the economics of removing insulation from distribution transformers. The study was done with the help of Wisconsin Power and Light (WP&L). At the time the protective margins of distribution arresters were adequate but not excessive. Most of the economics could be realized in the costs of accessories such as replacing the 125kV BIL transformer bushings with the high volume 95kV BIL bushing. After the project`s completion, discussions with WP&L led to transformer tear downs to determine why their transformers were failing. Their method of protection was to use a cross arm mounted primary arrester in parallel with a fuse cutout and the transformer. Prior to the WP&L tear downs the utility industry was aware of secondary surge failures at Florida Power Corporation where more than half of the non-interlaced transformer failures were due to low side current surges. The analysis of WP&L failed transformers indicated a high failure rate due to secondary surges of both interlaced and non-interlaced transformers. Additional tear downs at midwest and southeastern utilities provided similar results.

  6. Toward "metalloMOFzymes": Metal-Organic Frameworks with Single-Site Metal Catalysts for Small-Molecule Transformations.

    PubMed

    Cohen, Seth M; Zhang, Zhenjie; Boissonnault, Jake A

    2016-08-01

    Metal-organic frameworks (MOFs) are being increasingly studied as scaffolds and supports for catalysis. The solid-state structures of MOFs, combined with their high porosity, suggest that MOFs may possess advantages shared by both heterogeneous and homogeneous catalysts, with few of the shortcomings of either. Herein, efforts to create single-site catalytic metal centers appended to the organic ligand struts of MOFs will be discussed. Reactions important for advanced energy applications, such as H2 production and CO2 reduction, will be highlighted. Examining how these active sites can be introduced, their performance, and their existing limitations should provide direction for design of the next generation of MOF-based catalysts for energy-relevant, small-molecule transformations. Finally, the introduction of second-sphere interactions (e.g., hydrogen bonding via squaramide groups) as a possible route to enhancing the activity of these metal centers is reported.

  7. METALLICITY DISTRIBUTION FUNCTIONS OF FOUR LOCAL GROUP DWARF GALAXIES

    SciTech Connect

    Ross, Teresa L.; Holtzman, Jon; Saha, Abhijit; Anthony-Twarog, Barbara J. E-mail: holtz@nmsu.edu

    2015-06-15

    We present stellar metallicities in Leo I, Leo II, IC 1613, and Phoenix dwarf galaxies derived from medium (F390M) and broad (F555W, F814W) band photometry using the Wide Field Camera 3 instrument on board the Hubble Space Telescope. We measured metallicity distribution functions (MDFs) in two ways, (1) matching stars to isochrones in color–color diagrams and (2) solving for the best linear combination of synthetic populations to match the observed color–color diagram. The synthetic technique reduces the effect of photometric scatter and produces MDFs 30%–50% narrower than the MDFs produced from individually matched stars. We fit the synthetic and individual MDFs to analytical chemical evolution models (CEMs) to quantify the enrichment and the effect of gas flows within the galaxies. Additionally, we measure stellar metallicity gradients in Leo I and II. For IC 1613 and Phoenix our data do not have the radial extent to confirm a metallicity gradient for either galaxy. We find the MDF of Leo I (dwarf spheroidal) to be very peaked with a steep metal-rich cutoff and an extended metal-poor tail, while Leo II (dwarf spheroidal), Phoenix (dwarf transition), and IC 1613 (dwarf irregular) have wider, less peaked MDFs than Leo I. A simple CEM is not the best fit for any of our galaxies; therefore we also fit the “Best Accretion Model” of Lynden-Bell. For Leo II, IC 1613, and Phoenix we find similar accretion parameters for the CEM even though they all have different effective yields, masses, star formation histories, and morphologies. We suggest that the dynamical history of a galaxy is reflected in the MDF, where broad MDFs are seen in galaxies that have chemically evolved in relative isolation and narrowly peaked MDFs are seen in galaxies that have experienced more complicated dynamical interactions concurrent with their chemical evolution.

  8. Nanoscale Twinning and Martensitic Transformation in Shock-Deformed BCC Metals

    SciTech Connect

    Hsiung, L L

    2005-03-22

    Shock-induced twinning and martensitic transformation in BCC-based polycrystalline metals (Ta and U-6wt%Nb) have been observed and studied using transmission electron microscopy (TEM). The length-scale of domain thickness for both twin lamella and martensite phase is found to be smaller than 100 nm. While deformation twinning of {l_brace}112{r_brace}<111>-type is found in Ta when shock-deformed at 15 GPa, both twinning and martensitic transformation are found in Ta when shock-deformed at 45 GPa. Similar phenomena of nanoscale twinning and martensitic transformation are also found in U6Nb shock-deformed at 30 GPa. Since both deformation twinning and martensitic transformation occurred along the {l_brace}211{r_brace}{sub b} planes associated with high resolved shear stresses, it is suggested that both can be regarded as alternative paths for shear transformations to occur in shock-deformed BCC metals. Heterogeneous nucleation mechanisms for shock-induced twinning and martensitic transformation are proposed and discussed.

  9. Metal distribution characteristic of MSWI bottom ash in view of metal recovery.

    PubMed

    Xia, Yi; He, Pinjing; Shao, Liming; Zhang, Hua

    2017-02-01

    Bottom ash is the major by-product of municipal solid waste incineration (MSWI), and is often reused as an engineering material, such as road-base aggregate. However, some metals (especially aluminum) in bottom ash can react with water and generate gas that could cause expansion and failure of products containing the ash; these metals must be removed before the ash is utilized. The size distribution and the chemical speciation of metals in the bottom ash from two Chinese MSWI plants were examined in this study, and the recovery potential of metals from the ash was evaluated. The metal concentrations in these bottom ashes were lower than that generated in other developed countries. Specifically, the contents of Al, Fe, Cu and Zn were 18.9-29.2, 25.5-32.3, 0.7-1.0 and 1.6-2.5g/kg, respectively. Moreover, 44.9-57.0wt.% of Al and 55.6-75.4wt.% of Fe were distributed in bottom ash particles smaller than 5mm. Similarly, 46.6-79.7wt.% of Cu and 42.9-74.2wt.% of Zn were concentrated in particles smaller than 3mm. The Fe in the bottom ash mainly existed as hematite, and its chemical speciation was considered to limit the recovery efficiency of magnetic separation.

  10. Steep front short duration low voltage impulse performance of distribution transformers

    SciTech Connect

    Burrage, L.M.; Veverka, E.F.; McConnell, B.W.

    1987-01-01

    An extensive literature search of steep front short duration (SFSD) impulse sources, their characteristics and effect on power system equipment has led to the specification of a test program to evaluate key apparatus and insulations. Distribution transformers, although not overly susceptible to impulse damage, have been selected as one of the candidate apparatus for low and high voltage SFSD impulse tests. This paper covers the low voltage SFSD impulse response of conventional oil insulated shell form and core form distribution transformers.

  11. Metal distributions in soil receiving urban pavement runoff and snowmelt.

    PubMed

    Sansalone, John J; Glenn, Donald W

    2007-07-01

    Wet and dry deposition of anthropogenic metals and particulates generated from urban and traffic activities can result in contamination of urban-land-use soils. These particulate residuals encompass a wide size gradation, from 1 to greater than 10 000 microm. This study hypothesized that such contamination of surficial soils can be analyzed and explained as a function of the soil/residual granulometry. This study analyzed the gradation-based physical characteristics for 10 urban transportation land-use sites with soil/residual complexes (SRCs) located throughout metropolitan Cincinnati, Ohio, and an urban residential reference site. Particle density (rho(s)) of SRCs ranged from 2.8 to 2.1 g/cm3, with the lower particle density associated with particles less than 100 microm. For each site, specific surface area generally increased with decreasing particle size, while the predominance of total surface area was associated with the coarser size fractions, except for the clayey glacial till reference site not influenced by traffic. Cumulative analysis for lead, copper, cadmium, and zinc associated with SRCs indicated that more than 50% of the metal mass was associated with particles greater than 250 microm, with more than 80% associated with particles greater than 106 microm. Study results are similar to rainfall-runoff and snowmelt distributions. Results provide guidance when considering potential fate and control of metals transported by urban drainage and are distributed across the SRC size gradation.

  12. Main Group Lewis Acid-Mediated Transformations of Transition-Metal Hydride Complexes.

    PubMed

    Maity, Ayan; Teets, Thomas S

    2016-08-10

    This Review highlights stoichiometric reactions and elementary steps of catalytic reactions involving cooperative participation of transition-metal hydrides and main group Lewis acids. Included are reactions where the transition-metal hydride acts as a reactant as well as transformations that form the metal hydride as a product. This Review is divided by reaction type, illustrating the diverse roles that Lewis acids can play in mediating transformations involving transition-metal hydrides as either reactants or products. We begin with a discussion of reactions where metal hydrides form direct adducts with Lewis acids, elaborating the structure and dynamics of the products of these reactions. The bulk of this Review focuses on reactions where the transition metal and Lewis acid act in cooperation, and includes sections on carbonyl reduction, H2 activation, and hydride elimination reactions, all of which can be promoted by Lewis acids. Also included is a section on Lewis acid-base secondary coordination sphere interactions, which can influence the reactivity of hydrides. Work from the past 50 years is included, but the majority of this Review focuses on research from the past decade, with the intent of showcasing the rapid emergence of this field and the potential for further development into the future.

  13. Utilizing Hilbert-Huang transform in detection some of mechanical properties of the refractory metals

    NASA Astrophysics Data System (ADS)

    Mohammed, Arshed Abdulhamed; Haris, Sallehuddin Mohamed; Nuawi, Mohd Zaki

    2016-02-01

    This study is one of the first to report on the use of Hilbert-Huang transform (HHT) to determine the modulus of elasticity of a material, which is one of the most important properties of metals. In addition, this study involves an analytical study of the process of transfer of energy, which was represented in the form of intrinsic mode functions (IMFs). Moreover, the distribution of IMFs within the time-frequency-plain was determined by testing eight test specimens. Five test specimens were refractory materials, namely, Ti, Ti6AL4V, Zr, Nb, and Ta, and the other three were non-refractory materials, namely, Al, Brass, and ST4340. The new setup was composed of Mg and involves the use of two piezoelectric transducers, which were used as the emitter and receiver. The setup was designed and implemented in this research based on Mg usage to test the metals. First, a new relationship was derived between the pressure transmission coefficient (PTC) of the transmitted wave (through the emitter-water-test specimen-Mg to the receiver) and the corresponding values of the product of the density (ρ) and the modulus of elasticity (E) for the same test specimen. Another relationship was established between the PTCs and the total energy transmitted at high frequencies. This energy indicates the summation of IMFs that have high frequencies (THIMFs), higher than 10 kHz, can determine E better than TOF for most test specimens. To verify this results, with regard to the second conclusion, a new simulation for this setup was carried out using Simulink in MATLAB. Twelve theoretical tests were done, for high acoustic impedance metals, like Hf, Mo, WNiFe and W in addition to test the same group which was tested experimentally. The results of theoretical tests supported the experimental results except for Nb. Most of the conclusions were obtained through practical results and analytical studies. The results proved that THIMFs can determine the change in the microstructure of the alloys

  14. Specialties of distributions of alkaline-earth metals in coal

    SciTech Connect

    Fan Jinchuan; Fan Minqiang

    1997-12-31

    Four different ranks of coal have been sampled and separated into different density fractions by Float-Sink. The contents of some trace elements in each density fraction has been analyzed by ICAP. The analyzed data show that the alkaline-earth metals (Be, Sr, and Ba) have their special distributions in coal: Be and Sr may exist in the form of organic matter. Ba often has the highest content in the middle density fraction (1.4--1.5). The relative relationship between ash (or sulfur) and the trace element in a certain type of coal was obtained by using linear regression approach. Results show that there is no significant correlation between the contents of ash or sulfur and those of Be, Sr, and Ba. On the other hand, the linear regression was done among the trace elements of 17 types of coal. The results also show that there is no significant correlation between ash or sulfur and alkaline-earth metals.

  15. Effects of sulfate on heavy metal release from iron corrosion scales in drinking water distribution system.

    PubMed

    Sun, Huifang; Shi, Baoyou; Yang, Fan; Wang, Dongsheng

    2017-05-01

    Trace heavy metals accumulated in iron corrosion scales within a drinking water distribution system (DWDS) could potentially be released to bulk water and consequently deteriorate the tap water quality. The objective of this study was to identify and evaluate the release of trace heavy metals in DWDS under changing source water conditions. Experimental pipe loops with different iron corrosion scales were set up to simulate the actual DWDS. The effects of sulfate levels on heavy metal release were systemically investigated. Heavy metal releases of Mn, Ni, Cu, Pb, Cr and As could be rapidly triggered by sulfate addition but the releases slowly decreased over time. Heavy metal release was more severe in pipes transporting groundwater (GW) than in pipes transporting surface water (SW). There were strong positive correlations (R(2) > 0.8) between the releases of Fe and Mn, Fe and Ni, Fe and Cu, and Fe and Pb. When switching to higher sulfate water, iron corrosion scales in all pipe loops tended to be more stable (especially in pipes transporting GW), with a larger proportion of stable constituents (mainly Fe3O4) and fewer unstable compounds (β-FeOOH, γ-FeOOH, FeCO3 and amorphous iron oxides). The main functional iron reducing bacteria (IRB) communities were favorable for the formation of Fe3O4. The transformation of corrosion scales and the growth of sulfate reducing bacteria (SRB) accounted for the gradually reduced heavy metal release with time. The higher metal release in pipes transporting GW could be due to increased Fe6(OH)12CO3 content under higher sulfate concentrations.

  16. Spatial Variability and Distribution of the Metals in Surface Runoff in a Nonferrous Metal Mine

    PubMed Central

    Ren, Bozhi; Chen, Yangbo; Zhu, Guocheng; Wang, Zhenghua; Zheng, Xie

    2016-01-01

    The spatial variation and distribution features of the metals tested in the surface runoff in Xikuangshan Bao Daxing miming area were analyzed by combining statistical methods with a geographic information system (GIS). The results showed that the maximum concentrations of those five kinds of the metals (Sb, Zn, Cu, Pb, and Cd) in the surface runoff of the antimony mining area were lower than the standard value except the concentration of metal Ni. Their concentrations were 497.1, 2.0, 1.8, 22.2, and 22.1 times larger than the standard value, respectively. This metal pollution was mainly concentrated in local areas, which were seriously polluted. The variation coefficient of Sb, Zn, Cu, Ni, Pb, and Cd was between 0.4 to 0.6, wherein the Sb's spatial variability coefficient is 50.56%, indicating a strong variability. Variation coefficients of the rest of metals were less than 50%, suggesting a moderate variability. The spatial structure analysis showed that the squared correlation coefficient (R2) of the models fitting for Sb, Zn, Cu, Ni, Pb, and Cd was between 0.721 and 0.976; the ratio of the nugget value (C0) to the abutment value (C + C0) was between 0.0767 and 0.559; the semivariogram of Sb, Zn, Ni, and Pb was in agreement with a spherical model, while semivariogram of Cu and Cd was in agreement with Gaussian model, and both had a strong spatial correlation. The trend and spatial distribution indicated that those pollution distributions resulting from Ni, Pb, and Cd are similar, mainly concentrated in both ends of north and south in eastern part. The main reasons for the pollution were attributed to the residents living, transportation, and industrial activities; the Sb distribution was concentrated mainly in the central part, of which the pollution was assigned to the mining and the industrial activity; the pollution distributions of Zn and Cu were similar, mainly concentrated in both ends of north and south as well as in west; the sources of the metals were

  17. Hydrogen-Induced Phase Transformations: a Base for a New Sphere of the Science of Metals (an Analytical Review)

    NASA Astrophysics Data System (ADS)

    Goltsov, V. A.

    2017-03-01

    Data on the phase transformations induced in metals by hydrogen are generalized and analyzed. It is suggested to classify hydrogen-induced phase transformations on the basis of allowance for the temperature dependence of the parameters of diffusion of substitutional and interstitial (hydrogen) atoms like in the classical science of metals. A pioneer classification of hydrogen-induced phase transformations by this method is developed.

  18. The Cortex Transform as an image preprocessor for sparse distributed memory: An initial study

    NASA Technical Reports Server (NTRS)

    Olshausen, Bruno; Watson, Andrew

    1990-01-01

    An experiment is described which was designed to evaluate the use of the Cortex Transform as an image processor for Sparse Distributed Memory (SDM). In the experiment, a set of images were injected with Gaussian noise, preprocessed with the Cortex Transform, and then encoded into bit patterns. The various spatial frequency bands of the Cortex Transform were encoded separately so that they could be evaluated based on their ability to properly cluster patterns belonging to the same class. The results of this study indicate that by simply encoding the low pass band of the Cortex Transform, a very suitable input representation for the SDM can be achieved.

  19. Regulating the spatial distribution of metal nanoparticles within metal-organic frameworks to enhance catalytic efficiency

    PubMed Central

    Yang, Qiu; Liu, Wenxian; Wang, Bingqing; Zhang, Weina; Zeng, Xiaoqiao; Zhang, Cong; Qin, Yongji; Sun, Xiaoming; Wu, Tianpin; Liu, Junfeng; Huo, Fengwei; Lu, Jun

    2017-01-01

    Composites incorporating metal nanoparticles (MNPs) within metal-organic frameworks (MOFs) have broad applications in many fields. However, the controlled spatial distribution of the MNPs within MOFs remains a challenge for addressing key issues in catalysis, for example, the efficiency of catalysts due to the limitation of molecular diffusion within MOF channels. Here we report a facile strategy that enables MNPs to be encapsulated into MOFs with controllable spatial localization by using metal oxide both as support to load MNPs and as a sacrificial template to grow MOFs. This strategy is versatile to a variety of MNPs and MOF crystals. By localizing the encapsulated MNPs closer to the surface of MOFs, the resultant MNPs@MOF composites not only exhibit effective selectivity derived from MOF cavities, but also enhanced catalytic activity due to the spatial regulation of MNPs as close as possible to the MOF surface. PMID:28195131

  20. Regulating the spatial distribution of metal nanoparticles within metal-organic frameworks to enhance catalytic efficiency

    NASA Astrophysics Data System (ADS)

    Yang, Qiu; Liu, Wenxian; Wang, Bingqing; Zhang, Weina; Zeng, Xiaoqiao; Zhang, Cong; Qin, Yongji; Sun, Xiaoming; Wu, Tianpin; Liu, Junfeng; Huo, Fengwei; Lu, Jun

    2017-02-01

    Composites incorporating metal nanoparticles (MNPs) within metal-organic frameworks (MOFs) have broad applications in many fields. However, the controlled spatial distribution of the MNPs within MOFs remains a challenge for addressing key issues in catalysis, for example, the efficiency of catalysts due to the limitation of molecular diffusion within MOF channels. Here we report a facile strategy that enables MNPs to be encapsulated into MOFs with controllable spatial localization by using metal oxide both as support to load MNPs and as a sacrificial template to grow MOFs. This strategy is versatile to a variety of MNPs and MOF crystals. By localizing the encapsulated MNPs closer to the surface of MOFs, the resultant MNPs@MOF composites not only exhibit effective selectivity derived from MOF cavities, but also enhanced catalytic activity due to the spatial regulation of MNPs as close as possible to the MOF surface.

  1. Structure in the 3D Galaxy Distribution. III. Fourier Transforming the Universe: Phase and Power Spectra

    NASA Technical Reports Server (NTRS)

    Scargle, Jeffrey D.; Way, M. J.; Gazis, P. G.

    2017-01-01

    We demonstrate the effectiveness of a relatively straightforward analysis of the complex 3D Fourier transform of galaxy coordinates derived from redshift surveys. Numerical demonstrations of this approach are carried out on a volume-limited sample of the Sloan Digital Sky Survey redshift survey. The direct unbinned transform yields a complex 3D data cube quite similar to that from the Fast Fourier Transform of finely binned galaxy positions. In both cases, deconvolution of the sampling window function yields estimates of the true transform. Simple power spectrum estimates from these transforms are roughly consistent with those using more elaborate methods. The complex Fourier transform characterizes spatial distributional properties beyond the power spectrum in a manner different from (and we argue is more easily interpreted than) the conventional multipoint hierarchy. We identify some threads of modern large-scale inference methodology that will presumably yield detections in new wider and deeper surveys.

  2. Transformation of heavy metal fractions on soil urease and nitrate reductase activities in copper and selenium co-contaminated soil.

    PubMed

    Hu, Bin; Liang, Dongli; Liu, Juanjuan; Lei, Lingming; Yu, Dasong

    2014-12-01

    This study aims to explore the effects of the distribution, transformation and bioavailability of different fractions of copper (Cu) and selenium (Se) in co-contaminated soils on soil enzymes, providing references for the phytoremediation of contaminated areas and agriculture environmental protection. Pot experiments and laboratory analysis were used to investigate the transformation and bioavailability of additional Cu and Se for pakchoi (Brassica chinensis) in co-contaminated soil. In the uncontaminated soil, Cu mainly existed in residual form, whereas Se was present in residual form and in elemental and organic-sulfide matter-bound form. In the contaminated soil, Cu mainly bound to Fe-Mn oxidates, whereas Se was in exchangeable and carbonates forms. After a month of pakchoi growth, Cu tended to transfer into organic matter-bound fractions, whereas Se tended to bound to Fe-Mn oxidates. The IR (reduced partition index) value of Cu decreased as the concentrations of Cu and Se gradually increased, whereas the IR value of Se decreased as the concentration of Se increased. The IR value before pakchoi planting and after it was harvested was not affected by the concentration of exogenous Cu. Soil urease and nitrate reductase activities were inhibited by Cu and Se pollution either individually or combined in different degrees, following the order nitrate reductase>urease. The significant correlation between the IR value and soil enzyme activities suggests that this value could be used to evaluate the bioavailability of heavy metals in soil. Path analysis showed that the variations in exchangeable Cu and organic-sulfide matter-bound and elemental Se had direct effects on the activities of the two enzymes, suggesting their high bioavailability. Therefore, the IR value and the transformation of metals in soil could be used as indicators in evaluating the bioavailability of heavy metals. Copyright © 2014 Elsevier Inc. All rights reserved.

  3. Controlling the plasmonic surface waves of metallic nanowires by transformation optics

    SciTech Connect

    Liu, Yichao; Yuan, Jun; Yin, Ge; Ma, Yungui; He, Sailing

    2015-07-06

    In this letter, we introduce the technique of using transformation optics to manipulate the mode states of surface plasmonic waves of metallic nanowire waveguides. As examples we apply this technique to design two optical components: a three-dimensional (3D) electromagnetic mode rotator and a mode convertor. The rotator can rotate the polarization state of the surface wave around plasmonic nanowires by arbitrarily desired angles, and the convertor can transform the surface wave modes from one to another. Full-wave simulation is performed to verify the design and efficiency of our devices. Their potential application in photonic circuits is envisioned.

  4. Steering light by a sub-wavelength metallic grating from transformation optics

    PubMed Central

    Xu, Yadong; Fu, Yangyang; Chen, Huanyang

    2015-01-01

    Transformation optics has shown great ability in designing devices with novel functionalities, such as invisibility cloaking. A recent work shows that it can also be used to design metasurfaces which usually come from the concept of phase discontinuities. However, metasurfaces from transformation optics have very complicated material parameters. Here in this work, we propose a practical design, a sub-wavelength metallic grating with discrete and gradient index materials. Such a design not only inherits some functionalities of metasurfaces from phase discontinuities, but also shows richer physics. Our work will also provide a guidance to recent activities of acoustic metasurfaces, especially for those made of extremely anisotropic metamaterials. PMID:26183391

  5. Steering light by a sub-wavelength metallic grating from transformation optics.

    PubMed

    Xu, Yadong; Fu, Yangyang; Chen, Huanyang

    2015-07-17

    Transformation optics has shown great ability in designing devices with novel functionalities, such as invisibility cloaking. A recent work shows that it can also be used to design metasurfaces which usually come from the concept of phase discontinuities. However, metasurfaces from transformation optics have very complicated material parameters. Here in this work, we propose a practical design, a sub-wavelength metallic grating with discrete and gradient index materials. Such a design not only inherits some functionalities of metasurfaces from phase discontinuities, but also shows richer physics. Our work will also provide a guidance to recent activities of acoustic metasurfaces, especially for those made of extremely anisotropic metamaterials.

  6. Controlled insulator-to-metal transformation in printable polymer composites with nanometal clusters

    NASA Astrophysics Data System (ADS)

    Sivaramakrishnan, Sankaran; Chia, Perq-Jon; Yeo, Yee-Chia; Chua, Lay-Lay; Ho, Peter K.-H.

    2007-02-01

    Although organic semiconductors have received the most attention, the development of compatible passive elements, such as interconnects and electrodes, is also central to plastic electronics. For this, ligand-protected metal-cluster films have been shown to anneal at low temperatures below 250∘C to highly conductive metal films, but they suffer from cracking and inadequate substrate adhesion. Here, we report printable metal-cluster-polymer nanocomposites that anneal to a controlled-percolation nanostructure without complete sintering of the metal clusters. This overcomes the previous challenges while still retaining the desired low transformation temperatures. Highly water- and alcohol-soluble gold clusters (75mgml-1) were synthesized and homogeneously dispersed into poly(3,4-ethylenedioxythiophene) to give a material with annealed d.c. conductivity tuneable between 10-4 and 105Scm-1. These composites can inject holes efficiently into all-printed polymer organic transistors. The insulator-metal transformation can also be electrically induced at 1MVcm-1, suggesting possible memory applications.

  7. Selective transformations of cyclopentadienyl ligands of transition-metal and rare-earth metal complexes.

    PubMed

    Liu, Ruiting; Zhou, Xigeng

    2013-04-21

    Cyclopentadienyl and substituted cyclopentadienyl ligands are observed in a wide range of organometallic complexes. In addition to serving as ancillary ligands, these ligands have come into their own as intermediates in organometallic reactions, and shown many unique reaction modes involving ring C-H, C-C and C=C bond cleavages. This feature article summarizes the progressive development of cyclopentadienyl-based reactions of metallocene complexes of transition metals and rare-earth metals, with the aim of further developing the fundamental modes of reactivity of such systems together with their synthetic applications.

  8. Light-Induced In Situ Transformation of Metal Clusters to Metal Nanocrystals for Photocatalysis.

    PubMed

    Xiao, Fang-Xing; Zeng, Zhiping; Hsu, Shao-Hui; Hung, Sung-Fu; Chen, Hao Ming; Liu, Bin

    2015-12-30

    In situ transformation of glutathione-capped gold (Aux) clusters to gold (Au) nanocrystals under simulated solar light irradiation was achieved and utilized as a facile synthetic approach to rationally fabricate Aux/Au/TiO2 ternary and Au/TiO2 binary heterostructures. Synergistic interaction of Aux clusters and Au nanocrystals contributes to enhanced visible-light-driven photocatalysis.

  9. Particle-size-distribution measurement using a Hankel transform of a Fraunhofer diffraction spectrum.

    PubMed

    Nakadate, S; Saito, H

    1983-11-01

    A new method for the measurement of the size distribution of circular particles by using a Fraunhofer diffraction pattern is proposed, which basically consists of performing the following two steps: (1) a Hankel transform of the radial spectral intensity that is diffracted from randomly distributed circular objects and (2) a calculation of a correlation between the Hankel-transformed function and a characteristic operator, such as a digital third-derivative operator. The method provides continuous size distribution of circular objects with high resolution.

  10. Metal-induced rapid transformation of diamond into single and multilayer graphene on wafer scale

    PubMed Central

    Berman, Diana; Deshmukh, Sanket A.; Narayanan, Badri; Sankaranarayanan, Subramanian K. R. S.; Yan, Zhong; Balandin, Alexander A.; Zinovev, Alexander; Rosenmann, Daniel; Sumant, Anirudha V.

    2016-01-01

    The degradation of intrinsic properties of graphene during the transfer process constitutes a major challenge in graphene device fabrication, stimulating the need for direct growth of graphene on dielectric substrates. Previous attempts of metal-induced transformation of diamond and silicon carbide into graphene suffers from metal contamination and inability to scale graphene growth over large area. Here, we introduce a direct approach to transform polycrystalline diamond into high-quality graphene layers on wafer scale (4 inch in diameter) using a rapid thermal annealing process facilitated by a nickel, Ni thin film catalyst on top. We show that the process can be tuned to grow single or multilayer graphene with good electronic properties. Molecular dynamics simulations elucidate the mechanism of graphene growth on polycrystalline diamond. In addition, we demonstrate the lateral growth of free-standing graphene over micron-sized pre-fabricated holes, opening exciting opportunities for future graphene/diamond-based electronics. PMID:27373740

  11. Metal-induced rapid transformation of diamond into single and multilayer graphene on wafer scale

    SciTech Connect

    Berman, Diana; Deshmukh, Sanket; Narayanan, Badri; Sankaranarayanan, Subramanian K.R.S.; Yan, Zhong; Balandin, Alexander A.; Zinovev, Alexander; Rosenmann, Daniel; Sumant, Anirudha V.

    2016-07-04

    The degradation of intrinsic properties of graphene during the transfer process constitutes a major challenge in graphene device fabrication, stimulating the need for direct growth of graphene on dielectric substrates. Previous attempts of metal-induced transformation of diamond and silicon carbide into graphene suffers from metal contamination and inability to scale graphene growth over large area. Here in this article, we introduce a direct approach to transform polycrystalline diamond into high-quality graphene layers on wafer scale (4 inch in diameter) using a rapid thermal annealing process facilitated by a nickel, Ni thin film catalyst on top. We show that the process can be tuned to grow single or multilayer graphene with good electronic properties. Molecular dynamics simulations elucidate the mechanism of graphene growth on polycrystalline diamond. Additionally, we demonstrate the lateral growth of free-standing graphene over micron-sized pre-fabricated holes, opening exciting opportunities for future graphene/diamond-based electronics.

  12. Metal-induced rapid transformation of diamond into single and multilayer graphene on wafer scale

    NASA Astrophysics Data System (ADS)

    Berman, Diana; Deshmukh, Sanket A.; Narayanan, Badri; Sankaranarayanan, Subramanian K. R. S.; Yan, Zhong; Balandin, Alexander A.; Zinovev, Alexander; Rosenmann, Daniel; Sumant, Anirudha V.

    2016-07-01

    The degradation of intrinsic properties of graphene during the transfer process constitutes a major challenge in graphene device fabrication, stimulating the need for direct growth of graphene on dielectric substrates. Previous attempts of metal-induced transformation of diamond and silicon carbide into graphene suffers from metal contamination and inability to scale graphene growth over large area. Here, we introduce a direct approach to transform polycrystalline diamond into high-quality graphene layers on wafer scale (4 inch in diameter) using a rapid thermal annealing process facilitated by a nickel, Ni thin film catalyst on top. We show that the process can be tuned to grow single or multilayer graphene with good electronic properties. Molecular dynamics simulations elucidate the mechanism of graphene growth on polycrystalline diamond. In addition, we demonstrate the lateral growth of free-standing graphene over micron-sized pre-fabricated holes, opening exciting opportunities for future graphene/diamond-based electronics.

  13. H II Region Metallicity Distribution in the Milky Way Disk

    NASA Astrophysics Data System (ADS)

    Balser, Dana S.; Rood, Robert T.; Bania, T. M.; Anderson, L. D.

    2011-09-01

    The distribution of metals in the Galaxy provides important information about galaxy formation and evolution. H II regions are the most luminous objects in the Milky Way at mid-infrared to radio wavelengths and can be seen across the entire Galactic disk. We used the National Radio Astronomy Observatory (NRAO) Green Bank Telescope to measure radio recombination line and continuum emission in 81 Galactic H II regions. We calculated LTE electron temperatures using these data. In thermal equilibrium metal abundances are expected to set the nebular electron temperature with high abundances producing low temperatures. Our H II region distribution covers a large range of Galactocentric radius (5-22 kpc) and samples the Galactic azimuth range 330°-60°. Using our highest quality data (72 objects) we derived an O/H Galactocentric radial gradient of -0.0383 ± 0.0074 dex kpc-1. Combining these data with a similar survey made with the NRAO 140 Foot telescope we get a radial gradient of -0.0446 ± 0.0049 dex kpc-1 for this larger sample of 133 nebulae. The data are well fit by a linear model and no discontinuities are detected. Dividing our sample into three Galactic azimuth regions produced significantly different radial gradients that range from -0.03 to -0.07 dex kpc-1. These inhomogeneities suggest that metals are not well mixed at a given radius. We stress the importance of homogeneous samples to reduce the confusion of comparing data sets with different systematics. Galactic chemical evolution models typically derive chemical evolution along only the radial dimension with time. Future models should consider azimuthal evolution as well.

  14. Metallicity Distribution Functions of Four Local Group Dwarf Galaxies

    NASA Astrophysics Data System (ADS)

    Ross, Teresa L.; Holtzman, Jon; Saha, Abhijit; Anthony-Twarog, Barbara J.

    2015-06-01

    We present stellar metallicities in Leo I, Leo II, IC 1613, and Phoenix dwarf galaxies derived from medium (F390M) and broad (F555W, F814W) band photometry using the Wide Field Camera 3 instrument on board the Hubble Space Telescope. We measured metallicity distribution functions (MDFs) in two ways, (1) matching stars to isochrones in color-color diagrams and (2) solving for the best linear combination of synthetic populations to match the observed color-color diagram. The synthetic technique reduces the effect of photometric scatter and produces MDFs 30%-50% narrower than the MDFs produced from individually matched stars. We fit the synthetic and individual MDFs to analytical chemical evolution models (CEMs) to quantify the enrichment and the effect of gas flows within the galaxies. Additionally, we measure stellar metallicity gradients in Leo I and II. For IC 1613 and Phoenix our data do not have the radial extent to confirm a metallicity gradient for either galaxy. We find the MDF of Leo I (dwarf spheroidal) to be very peaked with a steep metal-rich cutoff and an extended metal-poor tail, while Leo II (dwarf spheroidal), Phoenix (dwarf transition), and IC 1613 (dwarf irregular) have wider, less peaked MDFs than Leo I. A simple CEM is not the best fit for any of our galaxies; therefore we also fit the “Best Accretion Model” of Lynden-Bell. For Leo II, IC 1613, and Phoenix we find similar accretion parameters for the CEM even though they all have different effective yields, masses, star formation histories, and morphologies. We suggest that the dynamical history of a galaxy is reflected in the MDF, where broad MDFs are seen in galaxies that have chemically evolved in relative isolation and narrowly peaked MDFs are seen in galaxies that have experienced more complicated dynamical interactions concurrent with their chemical evolution. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is

  15. Controlled Encapsulation of Functional Organic Molecules within Metal-Organic Frameworks: In Situ Crystalline Structure Transformation.

    PubMed

    Guan, Jinju; Hu, Yu; Wang, Yu; Li, Hongfeng; Xu, Zhiling; Zhang, Tao; Wu, Peng; Zhang, Suoying; Xiao, Gengwu; Ji, Wenlan; Li, Linjie; Zhang, Meixuan; Fan, Yun; Li, Lin; Zheng, Bing; Zhang, Weina; Huang, Wei; Huo, Fengwei

    2017-01-23

    Functional organic molecules/metal-organic frameworks composites can be obtained by in situ crystalline structure transformation from ZIF-L to ZIF-8-L under double solvent conditions. Interestingly, the as-prepared molecules/ZIF-8-L composites with the leaf-like morphology exhibit good fluorescence properties and size selectivity in fluorescent quenchers due to the molecular sieving effect of the well-defined microporous ZIF-8-L.

  16. [Effects of stabilization treatment on migration and transformation of heavy metals in mineral waste residues].

    PubMed

    Zhao, Shu-Hua; Chen, Zhi-Liang; Zhang, Tai-Ping; Pan, Wei-Bin; Peng, Xiao-Chun; Che, Rong; Ou, Ying-Juan; Lei, Guo-Jian; Zhou, Ding

    2014-04-01

    Different forms of heavy metals in soil will produce different environmental effects, and will directly influence the toxicity, migration and bioavailability of heavy metals. This study used lime, fly ash, dried sludge, peanut shells as stabilizers in the treatment of heavy metals in mineral waste residues. Morphological analyses of heavy metal, leaching experiments, potted plant experiments were carried out to analyze the migration and transformation of heavy metals. The results showed that after adding stabilizers, the pH of the acidic mineral waste residues increased to more than neutral, and the organic matter content increased significantly. The main existing forms of As, Pb, and Zn in the mineral waste residues were the residual. The contents of exchangeable and organic matter-bound As decreased by 65.6% and 87.7% respectively after adding fly ash, dried sludge and peanut shells. Adding lime, fly ash and peanut shells promoted the transformation of As from the Fe-Mn oxide-bound to the carbonate-bound, and adding lime and fly ash promoted the transformation of Pb and Zn from the exchangeable, Fe-Mn oxide-bound, organic matter-bound to the residual. After the early stage of the stabilization treatment, the contents of As, Pb and Zn in the leachate had varying degrees of decline, and adding peanut shells could reduce the contents of As, Pb and Zn in the leachate further. Among them, the content of As decreased most significantly after treatment with fly ash, dried sludge and peanut shells, with a decline of 57.4%. After treatment with lime, fly ash and peanut shells, the content of Zn decreased most significantly, by 24.9%. The addition of stabilizers was advantageous to the germination and growth of plants. The combination of fly ash, dried sludge and peanut shell produced the best effect, and the Vetiveria zizanioides germination rate reached 76% in the treated wasted mineral residues.

  17. Pressure-induced Transformations of Dense Carbonyl Sulfide to Singly Bonded Amorphous Metallic Solid

    NASA Astrophysics Data System (ADS)

    Kim, Minseob; Dias, Ranga; Ohishi, Yasuo; Matsuoka, Takehiro; Chen, Jing-Yin; Yoo, Choong-Shik

    2016-08-01

    The application of pressure, internal or external, transforms molecular solids into non-molecular extended network solids with diverse crystal structures and electronic properties. These transformations can be understood in terms of pressure-induced electron delocalization; however, the governing mechanisms are complex because of strong lattice strains, phase metastability and path dependent phase behaviors. Here, we present the pressure-induced transformations of linear OCS (R3m, Phase I) to bent OCS (Cm, Phase II) at 9 GPa an amorphous, one-dimensional (1D) polymer at 20 GPa (Phase III); and an extended 3D network above ~35 GPa (Phase IV) that metallizes at ~105 GPa. These results underscore the significance of long-range dipole interactions in dense OCS, leading to an extended molecular alloy that can be considered a chemical intermediate of its two end members, CO2 and CS2.

  18. Pressure-induced Transformations of Dense Carbonyl Sulfide to Singly Bonded Amorphous Metallic Solid

    PubMed Central

    Kim, Minseob; Dias, Ranga; Ohishi, Yasuo; Matsuoka, Takehiro; Chen, Jing-Yin; Yoo, Choong-Shik

    2016-01-01

    The application of pressure, internal or external, transforms molecular solids into non-molecular extended network solids with diverse crystal structures and electronic properties. These transformations can be understood in terms of pressure-induced electron delocalization; however, the governing mechanisms are complex because of strong lattice strains, phase metastability and path dependent phase behaviors. Here, we present the pressure-induced transformations of linear OCS (R3m, Phase I) to bent OCS (Cm, Phase II) at 9 GPa; an amorphous, one-dimensional (1D) polymer at 20 GPa (Phase III); and an extended 3D network above ~35 GPa (Phase IV) that metallizes at ~105 GPa. These results underscore the significance of long-range dipole interactions in dense OCS, leading to an extended molecular alloy that can be considered a chemical intermediate of its two end members, CO2 and CS2. PMID:27527241

  19. Electric field and space charge distribution measurement in transformer oil struck by impulsive high voltage

    NASA Astrophysics Data System (ADS)

    Sima, Wenxia; Guo, Hongda; Yang, Qing; Song, He; Yang, Ming; Yu, Fei

    2015-08-01

    Transformer oil is widely used in power systems because of its excellent insulation properties. The accurate measurement of electric field and space charge distribution in transformer oil under high voltage impulse has important theoretical and practical significance, but still remains challenging to date because of its low Kerr constant. In this study, the continuous electric field and space charge distribution over time between parallel-plate electrodes in high-voltage pulsed transformer oil based on the Kerr effect is directly measured using a linear array photoelectrical detector. Experimental results demonstrate the applicability and reliability of this method. This study provides a feasible approach to further study the space charge effects and breakdown mechanisms in transformer oil.

  20. Seeded growth of metal-doped plasmonic oxide heterodimer nanocrystals and their chemical transformation.

    PubMed

    Ye, Xingchen; Reifsnyder Hickey, Danielle; Fei, Jiayang; Diroll, Benjamin T; Paik, Taejong; Chen, Jun; Murray, Christopher B

    2014-04-02

    We have developed a generalized seeded-growth methodology for the synthesis of monodisperse metal-doped plasmonic oxide heterodimer nanocrystals (NCs) with a near-unity morphological yield. Using indium-doped cadmium oxide (ICO) as an example, we show that a wide variety of preformed metal NCs (Au, Pt, Pd, FePt, etc.) can serve as the seeds for the tailored synthesis of metal-ICO heterodimers with exquisite size, shape, and composition control, facilitated by the delayed nucleation mechanism of the CdO phase. The metal-ICO heterodimers exhibit broadly tunable near-infrared localized surface plasmon resonances, and dual plasmonic bands are observed for Au-ICO heterodimers. We further demonstrate that the oxide domain of the Au-ICO heterodimers can be selectively and controllably transformed into a series of partially and completely hollow cadmium chalcogenide nanoarchitectures with unprecedented structural complexity, leaving the metal domain intact. Our work not only represents an exciting addition to the rapidly expanding library of chemical reactions that produce colloidal hybrid NCs, but it also provides a general route for the bottom-up chemical design of multicomponent metal-oxide-semiconductor NCs in a rational and sequential manner.

  1. The role of microRNAs in metal carcinogen-induced cell malignant transformation and tumorigenesis.

    PubMed

    Humphries, Brock; Wang, Zhishan; Yang, Chengfeng

    2016-12-01

    MicroRNAs (miRNAs), an important component of epigenetic mechanisms of carcinogenesis, have been shown to play crucial roles in cancer initiation, metastasis, prognosis and responses to drug treatment and may serve as biomarkers for early diagnosis of cancer and tools for cancer therapy. Metal carcinogens, such as arsenic, cadmium, hexavalent chromium and nickel, are well-established human carcinogens causing various cancers upon long term exposure. However, the mechanism of metal carcinogenesis has not been well understood, which limits our capability to effectively diagnose and treat human cancers resulting from chronic metal carcinogen exposure. Over recent years, the role of miRNAs in metal carcinogenesis has been actively explored and a growing body of evidence indicates the critical involvement of miRNAs in metal carcinogenesis. This review aims to discuss recent studies showing that miRNAs play important roles in metal carcinogen-induced cell malignant transformation and tumorigenesis. Some thoughts for future further studies in this field are also presented. Copyright © 2016 Elsevier Ltd. All rights reserved.

  2. Role of Oxalic Acid Overexcretion in Transformations of Toxic Metal Minerals by Beauveria caledonica

    PubMed Central

    Fomina, M.; Hillier, S.; Charnock, J. M.; Melville, K.; Alexander, I. J.; Gadd, G. M.

    2005-01-01

    The fungus Beauveria caledonica was highly tolerant to toxic metals and solubilized cadmium, copper, lead, and zinc minerals, converting them into oxalates. This fungus was found to overexcrete organic acids with strong metal-chelating properties (oxalic and citric acids), suggesting that a ligand-promoted mechanism was the main mechanism of mineral dissolution. Our data also suggested that oxalic acid was the main mineral-transforming agent. Cadmium, copper, and zinc oxalates were precipitated by the fungus in the local environment and also in association with the mycelium. The presence of toxic metal minerals often led to the formation of mycelial cords, and in the presence of copper-containing minerals, these cords exhibited enhanced excretion of oxalic acid, which resulted in considerable encrustation of the cords by copper oxalate hydrate (moolooite). It was found that B. caledonica hyphae and cords were covered by a thick hydrated mucilaginous sheath which provided a microenvironment for chemical reactions, crystal deposition, and growth. Cryo-scanning electron microscopy revealed that mycogenic metal oxalates overgrew parental fungal hyphae, leaving a labyrinth of fungal tunnels within the newly formed mineral matter. X-ray absorption spectroscopy revealed that oxygen ligands played a major role in metal coordination within the fungal biomass during the accumulation of mobilized toxic metals by B. caledonica mycelium; these ligands were carboxylic groups in copper phosphate-containing medium and phosphate groups in pyromorphite-containing medium. PMID:15640211

  3. [Effects of applying sewage sludge on chemical form distribution and bioavailability of heavy metals in soil].

    PubMed

    Song, Lin-Lin; Tie, Mei; Zhang, Zhao-Hong; Hui, Xiu-Juan; Jing, Kui; Chen, Zhong-Lin; Zhang, Ying

    2012-10-01

    A pot experiment was conducted to study the effects of applying sewage sludge on the chemical form distribution of heavy metals (Cd, Pb, Cu and Zn) in soil and the transfer and accumulation of the heavy metals in soil-plant (ryegrass) system. With the application of sewage sludge, the contents of bioavailable Cd and Zn in soil increased significantly but that of bioavailable Pb in soil had a significant decrease, and the content of residual form Pb in soil increased by 33.3% -74.5%, compared with CK. When the application rate of sewage sludge was 50% (M/M) of soil, the contents of exchangeable and reducible Cu in soil only occupied 0.7% and 0.2% of the total Cu respectively. The application of sewage sludge promoted the Cd, Cu and Zn absorption while inhibited the Pb absorption by ryegrass. Multiple linear regression analysis showed that the Cd, Zn and Cu contents in ryegrass were positively correlated with the reducible Cd and Zn and oxidizable Cu contents in soil, respectively, and Pb content in ryegrass was highly correlated with the soil exchangeable and oxidizable Pb contents. After planting ryegrass, the oxidizable Cd and Cu in rhizosphere soil were transformed into exchangeable Cd and residual form Cu, respectively, the exchangeable and reducible Zn transformed into oxidizable Zn, whereas the bioavailability of Pb was less affected.

  4. Geomycology: biogeochemical transformations of rocks, minerals, metals and radionuclides by fungi, bioweathering and bioremediation.

    PubMed

    Gadd, Geoffrey M

    2007-01-01

    The study of the role that fungi have played and are playing in fundamental geological processes can be termed 'geomycology' and this article seeks to emphasize the fundamental importance of fungi in several key areas. These include organic and inorganic transformations and element cycling, rock and mineral transformations, bioweathering, mycogenic mineral formation, fungal-clay interactions, metal-fungal interactions, and the significance of such processes in the environment and their relevance to areas of environmental biotechnology such as bioremediation. Fungi are intimately involved in biogeochemical transformations at local and global scales, and although such transformations occur in both aquatic and terrestrial habitats, it is the latter environment where fungi probably have the greatest influence. Within terrestrial aerobic ecosystems, fungi may exert an especially profound influence on biogeochemical processes, particularly when considering soil, rock and mineral surfaces, and the plant root-soil interface. The geochemical transformations that take place can influence plant productivity and the mobility of toxic elements and substances, and are therefore of considerable socio-economic relevance, including human health. Of special significance are the mutualistic symbioses, lichens and mycorrhizas. Some of the fungal transformations discussed have beneficial applications in environmental biotechnology, e.g. in metal leaching, recovery and detoxification, and xenobiotic and organic pollutant degradation. They may also result in adverse effects when these processes are associated with the degradation of foodstuffs, natural products, and building materials, including wood, stone and concrete. It is clear that a multidisciplinary approach is essential to understand fully all the phenomena encompassed within geomycology, and it is hoped that this review will serve to catalyse further research, as well as stimulate interest in an area of mycology of global

  5. Visible Light Induced Organic Transformations Using Metal-Organic-Frameworks (MOFs).

    PubMed

    Deng, Xiaoyu; Li, Zhaohui; García, Hermenegildo

    2017-08-22

    With the aim of developing renewable energy based processes, researchers are paying increasing interest to light induced organic transformations. Metal-organic frameworks (MOFs), a class of micro-/mesoporous hybrid materials, are recently emerging as a new type of photoactive materials for organic syntheses due to their unique structural characteristics. In this Review, we summarized the recent applications of MOFs as photocatalysts for light induced organic transformations, including (1) oxidation of alcohols, amines, alkene, alkanes and sulfides; (2) hydroxylation of aromatic compounds like benzene; (3) activation of the C-H bonds to construct new C-C or C-X bonds; (4) atom-transfer radical polymerization (ATRP). This Review starts with general background information of using MOFs in photocatalysis, followed by a description of light induced organic transformations promoted by photoactive inorganic nodes and photocatalytic active ligands in MOFs, respectively. Thereafter, the use of MOFs as multifunctional catalysts for light induced organic transformations via an efficient merge of the metal/ligand/guest based catalysis where the photocatalytic activity of MOFs plays a key role are discussed. Finally, the limitations, challenges and the future perspective of the application of MOFs for light induced organic transformations were addressed. The objective of this Review is to serve as a starting point for other researchers to get into this largely unexplored field. It is also our goal to stimulate intensive research in this field for rational designing of MOF materials to overcome their current limitations in photocatalysis, which can lead to more creative visible-light-induced organic transformations. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Mineral transformations during the dissolution of uranium ore minerals by dissimilatory metal-reducing bacteria

    NASA Astrophysics Data System (ADS)

    Glasauer, S.; Weidler, P.; Fakra, S.; Tyliszczak, T.; Shuh, D.

    2011-12-01

    Carnotite minerals [X2(UO2)2(VO4)2]; X = K, Ca, Ba, Mn, Na, Cu or Pb] form the major ore of uranium in the Colorado Plateau. These deposits are highly oxidized and contain U(VI) and V(IV). The biotransformation of U(VI) bound in carnotite by bacteria during dissimilatory metal reduction presents a complex puzzle in mineral chemistry. Both U(VI) and V(V) can be respired by metal reducing bacteria, and the mineral structure can change depending on the associated counterion. We incubated anaerobic cultures of S. putrefaciens CN32 with natural carnotite minerals from southeastern Utah in a nutrient-limited defined medium. Strain CN32 is a gram negative bacterium and a terrestrial isolate from New Mexico. The mineral and metal transformations were compared to a system that contained similar concentrations of soluble U(VI) and V(V). Electron (SEM, TEM) microscopies and x-ray spectromicroscopy (STXM) were used in conjunction with XRD to track mineral changes, and bacterial survival was monitored throughout the incubations. Slow rates of metal reduction over 10 months for the treatment with carnotite minerals revealed distinct biotic and abiotic processes, providing insight on mineral transformation and bacteria-metal interactions. The bacteria existed as small flocs or individual cells attached to the mineral phase, but did not adsorb soluble U or V, and accumulated very little of the biominerals. Reduction of mineral V(V) necessarily led to a dismantling of the carnotite structure. Bioreduction of V(V) by CN32 contributed small but profound changes to the mineral system, resulting in new minerals. Abiotic cation exchange within the carnotite group minerals induced the rearrangement of the mineral structures, leading to further mineral transformation. In contrast, bacteria survival was poor for treatments with soluble U(VI) and V(V), although both metals were reduced completely and formed solid UO2 and VO2; we also detected V(III). For these treatments, the bacteria

  7. 77 FR 7281 - Energy Conservation Program: Energy Conservation Standards for Distribution Transformers

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-10

    ...The Energy Policy and Conservation Act of 1975 (EPCA), as amended, prescribes energy conservation standards for various consumer products and certain commercial and industrial equipment, including low-voltage dry-type distribution transformers, and directs the U.S. Department of Energy (DOE) to prescribe standards for various other products and equipment, including other types of distribution transformers. EPCA also requires DOE to determine whether more- stringent, amended standards would be technologically feasible and economically justified, and would save a significant amount of energy. In this notice, DOE proposes amended energy conservation standards for distribution transformers. The notice also announces a public meeting to receive comment on these proposed standards and associated analyses and results.

  8. Metal removal and associated binding fraction transformation in contaminated river sediment washed by different types of agents

    PubMed Central

    Wang, Hong; Liu, Tongzhou; Feng, Shuai; Zhang, Weihua

    2017-01-01

    In ex-situ washing, HCl, EDTA and H2O2 solutions can effectively extract heavy metals in river sediment. Nevertheless they often target different sediment components, possibly transforming metal species into more bioavailable and hence toxic ones. This study, in batch settings, investigated the influences of different types of washing agents (i.e. HCl, EDTA and H2O2) on metal (i.e. Cu and Zn) removal from contaminated river sediment, destroy or dissolution of sediment components, and transformation of metal fractions during chemical washing treatment. Additionally, bioavailability of these metals left in the washed sediment was assessed. Results showed that HCl obtained the highest Cu and Zn removal through destroying the reducible, oxidizable and residual sediment components. Meanwhile, it transformed metal fractions to acid extractable one, resulting in an increase in metal bioavailability. Thus, the feasibility of washing with HCl for sediment remediation shall be reconsidered due to the caused high metal bioavailability. EDTA was capable of removing metals via direct complexation of labile metal species and indirect dissolution of reducible and oxidizable sediment components, where the transformation of corresponding metal binding fraction may occur. H2O2 obtained the lowest total Cu and Zn removal, but it preferentially removed the oxidizable metal species by oxidizing sulfides in the sediment. The bioavailable levels of Cu and Zn in the sediment washed by EDTA or H2O2 seemed not increase. To maintain a good balance between labile metal species removal and avoiding increase of metal bioavailability, EDTA and H2O2 are promising additives for metal removal by sediment washing. PMID:28350832

  9. Metal removal and associated binding fraction transformation in contaminated river sediment washed by different types of agents.

    PubMed

    Wang, Hong; Liu, Tongzhou; Feng, Shuai; Zhang, Weihua

    2017-01-01

    In ex-situ washing, HCl, EDTA and H2O2 solutions can effectively extract heavy metals in river sediment. Nevertheless they often target different sediment components, possibly transforming metal species into more bioavailable and hence toxic ones. This study, in batch settings, investigated the influences of different types of washing agents (i.e. HCl, EDTA and H2O2) on metal (i.e. Cu and Zn) removal from contaminated river sediment, destroy or dissolution of sediment components, and transformation of metal fractions during chemical washing treatment. Additionally, bioavailability of these metals left in the washed sediment was assessed. Results showed that HCl obtained the highest Cu and Zn removal through destroying the reducible, oxidizable and residual sediment components. Meanwhile, it transformed metal fractions to acid extractable one, resulting in an increase in metal bioavailability. Thus, the feasibility of washing with HCl for sediment remediation shall be reconsidered due to the caused high metal bioavailability. EDTA was capable of removing metals via direct complexation of labile metal species and indirect dissolution of reducible and oxidizable sediment components, where the transformation of corresponding metal binding fraction may occur. H2O2 obtained the lowest total Cu and Zn removal, but it preferentially removed the oxidizable metal species by oxidizing sulfides in the sediment. The bioavailable levels of Cu and Zn in the sediment washed by EDTA or H2O2 seemed not increase. To maintain a good balance between labile metal species removal and avoiding increase of metal bioavailability, EDTA and H2O2 are promising additives for metal removal by sediment washing.

  10. Formation of nanostructured Group IIA metal activated sensors: The transformation of Group IIA metal compound sites

    NASA Astrophysics Data System (ADS)

    Tune, Travis C.; Baker, Caitlin; Hardy, Neil; Lin, Arthur; Widing, Timothy J.; Gole, James L.

    2015-05-01

    Trends in the Group IIA metal oxides and hydroxides of magnesium, calcium, and barium are unique in the periodic table. In this study we find that they display novel trends as decorating nanostructures for extrinsic semiconductor interfaces. The Group IIA metal ions are strong Lewis acids. We form these M2+ ions in aqueous solution and bring these solutions in contact with a porous silicon interface to form interfaces for conductometric measurements. Observed responses are consistent with the formation of MgO whereas the heavier elements display behaviors which suggest the effect of their more basic nature. Mg(OH)2, when formed, represents a weak base whereas the heavier metal hydroxides of Ca, Sr, and Ba are strong bases. However, the hydroxides tend to give up hydrogen and act as Brönsted acids. For the latter elements, the reversible interaction response of nanostructures deposited to the porous silicon (PS) interface is modified, as the formation of more basic sites appears to compete with M2+ Lewis acidity and hydroxide Brönsted acidity. Mg2+ forms an interface whose response to the analytes NH3 and NO is consistent with MgO and well explained by the recently developing Inverse Hard/Soft Acid/Base model. The behavior of the Ca2+ and Ba2+ decorated interfaces as they interact with the hard base NH3 follows a reversal of the model, indicating a decrease in acidic character as the observed conductometric response suggests the interaction with hydroxyl groups. A change from oxide-like to hydroxide-like constituents is supported by XPS studies. The changes in conductometric response is easily monitored in contrast to changes associated with the Group IIA oxides and hydroxides observed in XPS, EDAX, IR, and NMR measurements.

  11. A general purpose subroutine for fast fourier transform on a distributed memory parallel machine

    NASA Technical Reports Server (NTRS)

    Dubey, A.; Zubair, M.; Grosch, C. E.

    1992-01-01

    One issue which is central in developing a general purpose Fast Fourier Transform (FFT) subroutine on a distributed memory parallel machine is the data distribution. It is possible that different users would like to use the FFT routine with different data distributions. Thus, there is a need to design FFT schemes on distributed memory parallel machines which can support a variety of data distributions. An FFT implementation on a distributed memory parallel machine which works for a number of data distributions commonly encountered in scientific applications is presented. The problem of rearranging the data after computing the FFT is also addressed. The performance of the implementation on a distributed memory parallel machine Intel iPSC/860 is evaluated.

  12. Particle size distribution and metal content in street sediments

    SciTech Connect

    Viklander, M.

    1998-08-01

    Sediments that had accumulated during the winter season, and which were left at the surface when the snow had melted, were studied with regard to physical and chemical characteristics. The investigation was carried out in the city of Luleaa, which is located in northern Sweden. Sediment samples were collected in the city center and in a housing area at streets with different traffic loads. The results showed that the amount of the sediments at a street surface was evidently affected by the presence of a sidewalk. The street with a sidewalk accumulated much more sediment than the street without a sidewalk. Both of these streets had approximately the same traffic load. The sidewalk also affected the particle size distribution. The content of heavy metals in the sediments varied with the traffic load and the area type. The highest concentration of cadmium, lead, and zinc was found in the street with the highest traffic load.

  13. 78 FR 23335 - Energy Conservation Program: Energy Conservation Standards for Distribution Transformers

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-18

    ...The Energy Policy and Conservation Act of 1975 (EPCA), as amended, prescribes energy conservation standards for various consumer products and certain commercial and industrial equipment, including distribution transformers. EPCA also requires the U.S. Department of Energy (DOE) to determine whether more-stringent standards would be technologically feasible and economically justified, and would save a significant amount of energy. In this final rule, DOE is adopting more- stringent energy conservation standards for distribution transformers. It has determined that the amended energy conservation standards for this equipment would result in significant conservation of energy, and are technologically feasible and economically justified.

  14. Analytical method for distribution of metallic gasket contact stress

    NASA Astrophysics Data System (ADS)

    Feng, Xiu; Gu, Boqing; Wei, Long; Sun, Jianjun

    2008-11-01

    Metallic gasket seals have been widely used in chemical and petrochemical plants. The failure of sealing system will lead to enormous pecuniary loss, serious environment pollution and personal injury accident. The failure of sealing systems is mostly caused not by the strength of flanges or bolts but by the leakage of the connections. The leakage behavior of bolted flanged connections is related to the gasket contact stress. In particular, the non-uniform distribution of this stress in the radial direction caused by the flange rotational flexibility has a major influence on the tightness of bolted flanged connections. In this paper, based on Warters method and considering the operating pressure, the deformation of the flanges is analyzed theoretically, and the formula for calculating the angle of rotation of the flanges is derived, based on which and the mechanical property of the gasket material, the method for calculating the gasket contact stresses is put forward. The maximum stress at the gasket outer flank calculated by the analytical method is lower than that obtained by numerical simulation, but the mean stresses calculated by the two methods are nearly the same. The analytical method presented in this paper can be used as an engineering method for designing the metallic gasket connections.

  15. Nonlinear model of a distribution transformer appropriate for evaluating the effects of unbalanced loads

    NASA Astrophysics Data System (ADS)

    Toman, Matej; Štumberger, Gorazd; Štumberger, Bojan; Dolinar, Drago

    Power packages for calculation of power system transients are often used when studying and designing electromagnetic power systems. An accurate model of a distribution transformer is needed in order to obtain realistic values from these calculations. This transformer model must be derived in such a way that it is applicable when calculating those operating conditions appearing in practice. Operation conditions where transformers are loaded with nonlinear and unbalanced loads are especially challenging. The purpose of this work is to derive a three-phase transformer model that is appropriate for evaluating the effects of nonlinear and unbalanced loads. A lumped parameter model instead of a finite element (FE) model is considered in order to ensure that the model can be used in power packages for the calculation of power system transients. The transformer model is obtained by coupling electric and magnetic equivalent circuits. The magnetic equivalent circuit contains only three nonlinear reluctances, which represent nonlinear behaviour of the transformer. They are calculated by the inverse Jiles-Atherton (J-A) hysteresis model, while parameters of hysteresis are identified using differential evolution (DE). This considerably improves the accuracy of the derived transformer model. Although the obtained transformer model is simple, the simulation results show good agreement between measured and calculated results.

  16. Transformation and availability of nutrients and heavy metals during integrated composting-vermicomposting of sewage sludges.

    PubMed

    Hait, Subrata; Tare, Vinod

    2012-05-01

    Transformation and availability of nutrients and some heavy metals were assessed during the integrated composting-vermicomposting of both primary sewage sludge (PSS) and waste activated sewage sludge (WAS) using matured vermicompost as indigenous bulking material and employing Eisenia fetida as earthworm species. Vermicomposting resulted in significant increase in total N (TN) (PSS: 41.7-64.6%, F=11.6, P<0.05; WAS: 36.4-58.6%, F=6.4, P<0.05), water soluble N (WSN) (PSS: 37.1-50.5%, F=30.1, P<0.05; WAS: 40.1-53.0%, F=27.6, P<0.05), total P (TP) (PSS: 39.9-69.8%, F=27.1, P<0.05; WAS: 32.2-56.6%, F=21.4, P<0.05) and water soluble P (WSP) (PSS: 25.2-34.3%, F=163.9, P<0.05; WAS: 24.1-34.2%, F=144.3, P<0.05) as compared to the initial compost material depending on different experimental conditions. The study demonstrated that the vermicomposting significantly improved the availability of nutrients in sewage sludges. In addition, vermicomposting considerably reduced the availability of heavy metals except Fe and Mn, presumably by forming organic-bound complexes in spite of several fold increase in their total content. The environmental conditions (i.e., temperature and relative humidity), in general, showed significant effect on the transformation and availability of nutrients and heavy metals. There was no effect of earthworm density on the transformation and availability of heavy metals and nutrients except N and P, possibly due to prior exposure during acclimation period in sewage sludge. Copyright © 2012 Elsevier Inc. All rights reserved.

  17. Transformation of triclosan by laccase catalyzed oxidation: The influence of humic acid-metal binding process.

    PubMed

    Lu, Junhe; Shi, Yuanyuan; Ji, Yuefei; Kong, Deyang; Huang, Qingguo

    2017-01-01

    Laccase is a widely present extracellular phenoloxidase excreted by fungi, bacteria, and high plants. It is able to catalyze one-electron oxidation of phenolic compounds into radical intermediates that can subsequently couple to each other via covalent bonds. These reactions are believed to play an important role in humification process and the transformation of contaminants containing phenolic functionalities in the environment. In this study, we investigated the kinetics of triclosan transformation catalyzed by laccase. It was found that the rate of triclosan oxidation was first order to the concentrations of both substrate and enzyme. Humic acid (HA) could inhibit the reaction by quenching the radical intermediate of triclosan generated by laccase oxidation. Such inhibition was more significant in the presence of divalent metal cations. This is because that binding to metal ions neutralized the negative charge of HA molecules, thus making them more accessible to laccase molecule that is also negatively charged. Therefore, it has greater chance to quench the radical intermediate that is very unstable and can only diffuse a limited distance after being released from the enzyme catalytic center. Based on these understandings, a reaction model was developed by integration of metal-HA binding equilibriums and kinetic equations. This model precisely predicted the transformation rate of triclosan in the presence of HA and divalent metal ions including Ca(2+), Mg(2+), Cd(2+), Co(2+), Mn(2+), Ba(2+), and Zn(2+). Overall, this work reveals important insights into laccase catalyzed oxidative coupling process. Copyright © 2016 Elsevier Ltd. All rights reserved.

  18. Modeling of the Structure of Disordered Metallic Alloys and Its Transformation Under Thermal Forcing

    NASA Astrophysics Data System (ADS)

    Cress, Ryan Paul

    The morphology of disordered binary metallic alloys is investigated. The structure of disordered binary metallic alloys is modeled as a randomly close packed (RCP) assembly of atoms. It was observed through a 2-D binary hard sphere experiment that RCP structure can be modeled as a mixture of nano-crystallites and glassy matter. We define the degree of crystallinity as the fraction of atoms contained in nano-crystallites in an RCP medium. Nano-crystallites by size in a crystallite size distribution were determined experimentally to define the morphology of the RCP medium. Both the degree of crystallinity and the crystallite size distribution have been found to be determined by the composition of a given binary mixture. A 2-D Monte Carlo simulation was developed in order to replicate the RCP structure observed in the experiment which is then extended to cases of arbitrary composition. Crystallites were assumed to be spherical with isotropic cross sections. The number of atoms in an individual crystallite in 2-D is simply transformed into the number of atoms in 3-D; we then obtain the crystallite size distribution in 3-D. This experiment accounts for the contribution from the repulsive core of the inter-atomic potential. The attractive part of the potential is recovered by constructing spherical nano-crystallites of a given radius from a crystalline specimen of each given alloy. A structural model of a disordered alloy is thus obtained. With the basic structure of the RCP medium defined, the response to heating would be in the form of changes to the crystallite size distribution. This was first investigated in a hard sphere mechanical oven experiment. The experimental setup consists of a 2-D cell which is driven by two independent stepper motors. The motors drive a binary RCP bed of spheres on a slightly tilted plane according to a chaotic algorithmm. The motors are driven at four different speed settings. The RCP medium was analyzed using a sequence of digital images

  19. Steady-state analysis of the impact of climate change on distribution transformer

    NASA Astrophysics Data System (ADS)

    Almohaimeed, Sulaiman

    Climate change could cause several issues such as decreasing water availability, increasing intensity of storm events, flooding and sea level rise, increasing air, and water temperatures. One aspect of climate change is the increase in ambient temperature. According to, the average global surface temperature is expected to increase around 1.8° to 4°, while the average increase of global ambient temperature is predicted from 1.4° to 5.8°, in the periods of 1990 to 2100. Climate change can also affect distribution systems in terms of reliability and loadability. A 1° rise in global temperature increases peak demand by 4.6%. In 2013, U.S. weather-related power outages may have reached 180 events per year. Further, climate change leads to high temperature, and many factors might change. An increase in ambient temperature leads to increase in transformer loading, which leads to a reduction of lifetime of transformers and low insulation value due to degradation of degree of polymerization. As ambient temperature and operation temperature increase can cause thermal aging of transformers, it is important to control a loaded transformer to mitigate aging effect. Thus, demand response is an important and effective feature of thermal management of a transformer. Multiple models are discussed and explained to obtain accurate results and a good prediction for the three factors: ambient temperature, operation temperature, and demand response. Therefore, IEEE standard C57.91-2011 is used for calculating thermal characteristics and the loss of life of distribution transformers. It also provides an example using rated parameters of a 25 MVA distribution transformer, real data of temperature, load available in the public domain for Fort Collins, Colorado, USA. Moreover, demand response is considered in this calculation in order to study the effect of changing load levels on the transformer insulation life and aging acceleration factor. Four scenarios of load levels will be

  20. Voltage Distribution of Internal Windings of Pole-Mounted Distribution Transformer by Lightning Surge and Measures for Voltage Reduction

    NASA Astrophysics Data System (ADS)

    Honda, Hideki; Asakawa, Akira; Yokoyama, Shigeru

    When steep lightning surge enters a pole-mounted distribution transformer, the voltage distribution of the internal windings is unbalanced. It is known that a layer-to-layer short or a turn-to-turn short occurs where the voltage distribution of windings is high. In this paper, the voltage distribution of the windings was measured at the primary and secondary sides of the transformer using a testing transformer. The point of the windings where the highest voltage occurred was clarified. At the primary windings, large voltage occurs at the layer nearest the primary bushing, and the possibility of breakdown at this point is high. By field test using several types of surge arrestor, it is found that the lower the operating voltage of the surge arrestor installed in the primary side, the lower the voltage occurring at the primary windings. At the secondary windings, large voltage occurs at the layer closer to the neutral terminal, and the possibility of breakdown at this point is high. The lower the operating voltage of the surge arrestor installed in the primary side, the lower the voltage occurring at the secondary windings, too. Adding the surge arrestor in the secondary side, although effectively reduce line-to-line voltage, does not effectively reduce the voltage of the secondary windings.

  1. Nonlinear Color-Metallicity Relations of Globular Clusters. VII. Nonlinear Absorption-line Index versus Metallicity Relations and Bimodal Index Distributions of NGC 5128 Globular Clusters

    NASA Astrophysics Data System (ADS)

    Kim, Sooyoung; Yoon, Suk-Jin

    2017-07-01

    Spectroscopy on the globular cluster (GC) system of NGC 5128 revealed bimodality in absorption-line index distributions of its old GCs. GC division is a widely observed and studied phenomenon whose interpretation has depicted host galaxy formation and evolution such that it harbors two distinct metallicity groups. Such a conventional view of GC bimodality has mainly been based on photometry. The recent GC photometric data, however, presented an alternative perspective in which the nonlinear metallicity-to-color transformation is responsible for color bimodality of GC systems. Here we apply the same line of analysis to the spectral indices and examine the absorption-line index versus metallicity relations for the NGC 5128 GC system. NGC 5128 GCs display nonlinearity in the metallicity-index planes, most prominently for the Balmer lines and by a non-negligible degree for the metallicity-sensitive magnesium line. We demonstrate that the observed spectroscopic division of NGC 5128 GCs can be caused by the nonlinear nature of the metallicity-to-index conversions and thus one does not need to resort to two separate GC subgroups. Our analysis incorporating this nonlinearity provides a new perspective on the structure of NGC 5128's GC system, and a further piece to the global picture of the formation of GC systems and their host galaxies.

  2. Chirp-driven vibrational distribution in transition metal carbonyl complexes.

    PubMed

    Gollub, C; Korff, B M R; Kompa, K L; de Vivie-Riedle, R

    2007-01-21

    In this theoretical study vibrational ladder climbing in transition metal carbonyl complexes, as a possible means to initialize chemical ground state reactions, and the resulting vibrational population distribution using chirped mid-infrared femtosecond laser pulses is investigated. Our model system is MnBr(CO)(5), a strong IR-absorber within an experimentally easily accessible wavelength region. Special emphasis is put on the perturbation due to additional vibrational modes, especially on one, which allows dissociation at low energies. The related potential energy surface for the three representative modes is calculated, whereon quantum dynamics calculations, including the laser-molecule interaction, are performed. No significant coupling could be detected, neither in the bound, nor in the dissociative region. Contrarily, we found a dynamical barrier even for energies high above the dissociation limit. Different vibrational population distributions after the laser excitation of the CO stretching mode could be generated in dependence of the chirp parameters. Based on these findings we simulated the laser excitation corresponding to an experiment by M. Joffre et al., Proc. Natl. Acad. Ssi. U. S. A., 2004, 101(36), 13216-13220, where coherent vibrational ladder climbing in carboxyhemoglobin was demonstrated and we could offer an explanation for an open question, concerning the interpretation of the spectroscopic data.

  3. Phagocytosis and transforming activity of crystalline metal sulfide particles are related to their negative surface charge

    SciTech Connect

    Abbracchio, M.P.; Heck, J.D.; Costa, M.

    1982-01-01

    Crystalline nickel sulfide (alpha NiS) and cobalt sulfide (CoS2) particles can cause greater cell transformation and cellular toxicity than the respective amorphous metal sulfide particles. Cultured mammalian cells phagocytose the crystalline metal sulfide particles more readily than the amorphous ones. In the case of the nickel sulfides, the crystalline metal sulfide particles had negatively charged surfaces (Zeta potential: -27.012 mV) in contrast to the amorphous particles, which were positively charge (Zeta potential: +9.174 mV). X-ray photoelectron spectroscopy analysis of amorphous and crystalline NiS particles revealed that the outermost surface (1-4 nm) of the two particles had striking differences in Ni/S ratios and in their sulfur oxidation states. Rendering particles' surfaces more negative by reduction with lithium aluminum hydride enhanced their phagocytosis, and in the case of amorphous NiS chemical reduction resulted in an incidence of morphological transformation of Syrian hamster embryo cells comparable to that observed with untreated crystalline alpha NiS.

  4. Analyse de distributions fractales à partir de leur transformée en ondelettes

    NASA Astrophysics Data System (ADS)

    Muzy, Jean-François

    Using the continuous wavelet transform, we define a new formalism that provides a statistical description of the singularities of a fractal distribution. This wavelet based method is a generalization of the classical multifractal formalism developed for characterizing singular measures. Our purpose is illustrated on pedagogical examples including Brownian functions. For a particular class of fractal distributions, our heuristic considerations can be established in a rigourous way.

  5. Surface-Emitting Distributed Feedback Terahertz Quantum-Cascade Lasers in Metal-Metal Waveguides

    NASA Technical Reports Server (NTRS)

    Kumar, Sushil; Williams, Benjamin S.; Qin, Qi; Lee, Alan W. M.; Hu, Qing; Reno, John L.

    2007-01-01

    Single-mode surface-emitting distributed feedback terahertz quantumcascade lasers operating around 2.9 THz are developed in metal-metal waveguides. A combination of techniques including precise control of phase of reflection at the facets, and u e of metal on the sidewalls to eliminate higher-order lateral modes allow robust single-mode operation over a range of approximately 0.35 THz. Single-lobed far-field radiation pattern is obtained using a pi phase-shift in center of the second-order Bragg grating. A grating device operating at 2.93 THz lased up to 149 K in pulsed mode and a temperature tuning of 19 .7 GHz was observed from 5 K to 147 K. The same device lased up to 78 K in continuous-wave (cw) mode emitting more than 6 m W of cw power at 5 K. ln general, maximum temperature of pulsed operation for grating devices was within a few Kelvin of that of multi-mode Fabry-Perot ridge lasers

  6. Surface-Emitting Distributed Feedback Terahertz Quantum-Cascade Lasers in Metal-Metal Waveguides

    NASA Technical Reports Server (NTRS)

    Kumar, Sushil; Williams, Benjamin S.; Qin, Qi; Lee, Alan W. M.; Hu, Qing; Reno, John L.

    2007-01-01

    Single-mode surface-emitting distributed feedback terahertz quantumcascade lasers operating around 2.9 THz are developed in metal-metal waveguides. A combination of techniques including precise control of phase of reflection at the facets, and u e of metal on the sidewalls to eliminate higher-order lateral modes allow robust single-mode operation over a range of approximately 0.35 THz. Single-lobed far-field radiation pattern is obtained using a pi phase-shift in center of the second-order Bragg grating. A grating device operating at 2.93 THz lased up to 149 K in pulsed mode and a temperature tuning of 19 .7 GHz was observed from 5 K to 147 K. The same device lased up to 78 K in continuous-wave (cw) mode emitting more than 6 m W of cw power at 5 K. ln general, maximum temperature of pulsed operation for grating devices was within a few Kelvin of that of multi-mode Fabry-Perot ridge lasers

  7. Mechanism of Occurring Over-Voltage Phenomena in Distributed Power System on Energization of Transformers

    NASA Astrophysics Data System (ADS)

    Nakachi, Yoshiki; Ueda, Fukashi; Kajikawa, Takuya; Amau, Tooru; Kameyama, Hirokazu; Ito, Hisanori

    This paper verifies the mechanism of occurring over voltage phenomena in the distributed power system on energizing the transformer. This over-voltage, which is observed at the actual distributed power system, with heavy inrush current is found to occur at about 0.1-0.2sec after the energizing and continue for a duration of more than 0.1[sec]. There is a concern that this over-voltage may operate the protection relay and deteriorate the insulation of apparatus. It is basically caused by the resonance between the shunt capacitors and saturated/unsaturated magnetizing inductance of transformer, system inductance. By using analytical formulation of a simple equivalent circuit, its mechanism has been verified through simulations carried out by using EMTP. Moreover, the sympathetic interaction between transformers is prolonged the duration of the over-voltage by the field test data is discussed in this paper.

  8. 77 FR 10997 - Energy Conservation Program: Energy Conservation Standards for Distribution Transformers; Correction

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-24

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY 10 CFR Part 431 RIN 1904-AC04 Energy Conservation Program: Energy Conservation Standards for Distribution Transformers; Correction AGENCY: Office of Energy Efficiency and Renewable Energy, Department of Energy....

  9. 10 CFR 431.197 - Manufacturer's determination of efficiency for distribution transformers.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 10 Energy 3 2010-01-01 2010-01-01 false Manufacturer's determination of efficiency for distribution transformers. 431.197 Section 431.197 Energy DEPARTMENT OF ENERGY ENERGY CONSERVATION ENERGY... has a configuration of windings which allows for more than one nominal rated voltage, the manufacturer...

  10. Choosing a Transformation in Analyses of Insect Counts from Contagious Distributions with Low Means

    Treesearch

    W.D. Pepper; S.J. Zarnoch; G.L. DeBarr; P. de Groot; C.D. Tangren

    1997-01-01

    Guidelines based on computer simulation are suggested for choosing a transformation of insect counts from negative binomial distributions with low mean counts and high levels of contagion. Typical values and ranges of negative binomial model parameters were determined by fitting the model to data from 19 entomological field studies. Random sampling of negative binomial...

  11. Characterization of Solid State Phase Transformation in Continuously Heated and Cooled Ferritic Weld Metal

    SciTech Connect

    Narayana, B; Mills, Michael J.; Specht, Eliot D; Santella, Michael L; Babu, Sudarsanam Suresh

    2010-12-01

    Arc welding processes involve cooling rates that vary over a wide range (1-100 K/s). The final microstructire is thus a product of the heating and cooling cycles experienced by the weld in addition to the weld composition. It has been shown that the first phase to form under weld cooling conditions may not be that predicted by equilibrium calculations. The partitioning of different interstitial/substitutional alloying elements at high temperatures can dramatically affect the subsequent phase transformations. In order to understand the effect of alloying on phase transformation temperatures and final microstructures time-resolved X-ray diffraction technique has been successfully used for characterization. The work by Jacot and Rappaz on pearlitic steels provided insight into austenitization of hypoeutectic steels using a finite volume model. However there is very little work done on the effect of heating and cooling rates on the phase transformation paths in bainitic/martensitic steels and weld metals. Previous work on a weld with higher aluminum content, deposited with a FCAW-S process indicated that even at aluminum levels where the primary phase to solidify from liquid should be delta ferrite, non-equilibrium austenite was observed. The presence of inhomogeneity in composition of the parent microstructure has been attributed to differences in transformation modes, temperatures and microstructures in dual-phase, TRIP steels and ferritic welds. The objectives of the work included the identification of the stability regions of different phases during heating and cooling, differences in the effect of weld heating and cooling rates on the phase transformation temperatures, and the variation in phase fractions of austenite and ferrite in the two phase regions as a function of temperature. The base composition used for the present work is a Fe-1%Al-2%Mn-1%Ni-0.04%C weld metal. A pseudo-binary phase diagram shows the expected solidification path under equilibrium

  12. Carcinogenic potential of metal nanoparticles in BALB/3T3 cell transformation assay.

    PubMed

    Sighinolfi, G L; Artoni, E; Gatti, A M; Corsi, L

    2016-05-01

    Metal-based nanoparticles (NPs), are currently used in many application fields including consumer products, pharmaceuticals, and biomedical treatments. In spite to their wide applications, an in-depth study of their potential toxic effects is still lacking. The aim of the present research was to investigate the potential initiator or promoter-like activity of different metallic NPs such as gold, iron, cobalt, and cerium using the Balb/3T3 two-stage transformation assay. The results indicated that all the selected metallic NPs, except for cobalt, when used as initiators did not induce any transformation in Balb/3T3 cell line. Moreover, Au and Fe3 O4 NPs, when used in place of the tumor promoter treatment TPA, increased significantly the number of Foci/dish as compared to the MCA treatment alone. The number of Foci/dish was 2.6 for Au NPs and 2.13 for Fe3 O4 ones, similar to those obtained by the positive control treatment (MCA + TPA), whereas 1.27 for MCA treatment alone. On the contrary, CeO2 NPs did not show any difference in the number of Foci/dish, as compared to MCA alone, but it decreased the number of foci by 65% in comparison to the positive control (MCA + TPA). As expected, cobalt NPs showed an increased cytotoxicity and only a few surviving cells were found at the time of analysis showing a number of Foci/dish of 0.13. For the first time, our data clearly showed that Au and Fe3 O4 NPs act as promoters in the two stage transformational assay, suggesting the importance to fully investigate the NPs carcinogenic potential with different models. © 2014 Wiley Periodicals, Inc.

  13. Effects of biochar on nitrogen transformation and heavy metals in sludge composting.

    PubMed

    Liu, Wei; Huo, Rong; Xu, Junxiang; Liang, Shuxuan; Li, Jijin; Zhao, Tongke; Wang, Shutao

    2017-07-01

    Composting is regarded as an effective treatment to suppress pathogenic organisms and stabilize the organic material in sewage sludge. This study investigated the use of biochar as an amendment to improve the composting effectiveness and reduce the bioavailability of heavy metals and loss of nitrogen during composting. Biochar of 0%, 1%, 3%, 5% and 7% were added into a mixture of sludge and straw, respectively. The use of biochar, even in small amounts, altered the composting process and the properties of the end products. Biochar addition resulted in a higher pile temperature (66°C) and could reduce nitrogen loss by transforming ammonium into nitrite. In the 5% biochar group, the final product from sludge composting, ammonia nitrogen, decreased by 22.4% compared to the control, and nitrate nitrogen increased by 310.6%. Considering temperature and N transformation, the treatment with 5% biochar is suggested for sludge composting. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Transformation of acoustic waves in periodic metal grating sandwiched between piezoelectric and dielectric.

    PubMed

    Naumenko, Natalya F; Abbott, Benjamin P

    2011-10-01

    The mechanism of SAW transformation with variation of film thickness is investigated in a piezoelectric substrate with a metal grating overlaid by a dielectric film, via simulation and visualization of the acoustic fields. By way of example, two orientations of lithium niobate substrates are analyzed, YX-LN and 128°YX-LN, with a Cu grating and an isotropic silica glass overlay. The motions, which follow the wave propagation in the sagittal plane, are visualized within two periods of the grating, with added contour plots showing the shear horizontal displacements. The continuous transformation of the wave's nature is investigated for each wave propagating in the analyzed material structures when the film thickness is increased from zero to a few wavelengths. The examples of the SAW transformation into boundary waves and into plate modes of different polarization have been found and investigated. The behavior of the SAW characteristics in the grating is correlated with transformation of the wave structure with increasing overlay thickness.

  15. Influence of phase transformation on stress evolution during growth of metal thin films on silicon.

    PubMed

    Fillon, A; Abadias, G; Michel, A; Jaouen, C; Villechaise, P

    2010-03-05

    In situ stress measurements during two-dimensional growth of low mobility metal films on amorphous Si were used to demonstrate the impact of interface reactivity and phase transformation on stress evolution. Using Mo1-xSix films as examples, the results show that the tensile stress rise, which develops after the film has become crystalline, is correlated with an increase in lateral grain size. The origin of the tensile stress is attributed to the volume change resulting from the alloy crystallization, which occurs at a concentration-dependent critical thickness.

  16. Transformation and Precipitation of Toxic Metals by ’Pseudomonas maltophilia’

    DTIC Science & Technology

    1991-05-31

    Jackson has used plasmid DNA derived from strain 0-2 to transform various metal-resistance phenotypes into a recipient strain of E. coli. He has...PAGE 1 Of AUTRACT’ UNCLASSTJT UNCLASSIFIED UN CLAS SIF IED UL I4N7d.l~0SO Stanbato @Form 29S ( Rev . 24E91 A. RESEARCH OBJECTIVES The aims of this project...Barton and Thomas Zocco at Iew Mexico State University and Los Alamos National Laboratory, respectively. Examination by SEM of cultures of 0-2 grown in the

  17. TRANSFORMATION

    SciTech Connect

    LACKS,S.A.

    2003-10-09

    Transformation, which alters the genetic makeup of an individual, is a concept that intrigues the human imagination. In Streptococcus pneumoniae such transformation was first demonstrated. Perhaps our fascination with genetics derived from our ancestors observing their own progeny, with its retention and assortment of parental traits, but such interest must have been accelerated after the dawn of agriculture. It was in pea plants that Gregor Mendel in the late 1800s examined inherited traits and found them to be determined by physical elements, or genes, passed from parents to progeny. In our day, the material basis of these genetic determinants was revealed to be DNA by the lowly bacteria, in particular, the pneumococcus. For this species, transformation by free DNA is a sexual process that enables cells to sport new combinations of genes and traits. Genetic transformation of the type found in S. pneumoniae occurs naturally in many species of bacteria (70), but, initially only a few other transformable species were found, namely, Haemophilus influenzae, Neisseria meningitides, Neisseria gonorrheae, and Bacillus subtilis (96). Natural transformation, which requires a set of genes evolved for the purpose, contrasts with artificial transformation, which is accomplished by shocking cells either electrically, as in electroporation, or by ionic and temperature shifts. Although such artificial treatments can introduce very small amounts of DNA into virtually any type of cell, the amounts introduced by natural transformation are a million-fold greater, and S. pneumoniae can take up as much as 10% of its cellular DNA content (40).

  18. Understanding Dissolved and Colloidal Metal Transport and Transformation - Pathways for Aquatic Toxicity

    NASA Astrophysics Data System (ADS)

    Kimball, B. A.; Besser, J. M.

    2004-05-01

    transformation. Both processes lead to an enrichment of both copper and zinc in the mineral and algal coatings of cobbles and bed sediments where these metals enter the food web through benthic grazing, but the fates of these metals in stream food webs differ substantially. Zinc accumulates to high concentrations in grazing invertebrates but concentrations are substantially lower in higher-order consumers, whereas copper is passed more efficiently to higher order consumers and may pose risks of dietary toxicity to fish. Although this example addresses streams affected by mine drainage, these processes could be active and significant in many other settings where iron or other colloidal transport occurs.

  19. A Visual Insight into the Degradation of Metals Used in Drinking Water Distribution Systems Using AFM

    EPA Science Inventory

    Evaluating the fundamental corrosion and passivation of metallic copper used in drinking water distribution materials is important in understanding the overall mechanism of the corrosion process. Copper pipes are widely used for drinking water distribution systems and although it...

  20. A Visual Insight into the Degradation of Metals Used in Drinking Water Distribution Systems Using AFM

    EPA Science Inventory

    Evaluating the fundamental corrosion and passivation of metallic copper used in drinking water distribution materials is important in understanding the overall mechanism of the corrosion process. Copper pipes are widely used for drinking water distribution systems and although it...

  1. Numerical Simulations of the Metallicity Distribution in Dwarf Spheroidal Galaxies

    SciTech Connect

    Ripamonti, Emanuele; Tolstoy, E.; Helmi, A.; Battaglia, G.; Abel, T.; /KIPAC, Menlo Park

    2006-12-12

    Recent observations show that the number of stars with very low metallicities in the dwarf spheroidal satellites of the Milky Way is low, despite the low average metallicities of stars in these systems. We undertake numerical simulations of star formation and metal enrichment of dwarf galaxies in order to verify whether this result can be reproduced with ''standard'' assumptions. The answer is likely to be negative, unless some selection bias against very low metallicity stars is present in the observations.

  2. Three-phase cogenerator and transformer models for distribution system analysis

    SciTech Connect

    Chen, T.H.; Chen, M.S.; Inoue, T. . Energy Systems Research Center); Kotas, P.; Chebli, E.A. )

    1991-10-01

    This paper presents detailed three-phase cogenerator and transformer models for analyzing a large-scale distribution system. The cogenerator model presented here is significant in that it will represent the inherent generator phase imbalance due to distribution system imbalance. The cogenerators can be synchronous or induction and can be on either primary or secondary system. The transformer models consider the copper and core losses, the winding connection, the phase shifting between primary and secondary windings, and the off-nominal tapping. An individual phase, as opposed to a balanced three-phase, representation was employed. This approach is oriented toward applications in distribution system operational analysis rather than planning analysis. This difference should be properly emphasized. The misuse of the planning oriented method to analyze the operational behavior of the system will distort the explanation of the calculated results and lead to incorrect conclusions.

  3. Encapsulation of metal clusters within MFI via interzeolite transformations and direct hydrothermal syntheses and catalytic consequences of their confinement.

    PubMed

    Goel, Sarika; Zones, Stacey I; Iglesia, Enrique

    2014-10-29

    The encapsulation of metal clusters (Pt, Ru, Rh) within MFI was achieved by exchanging cationic metal precursors into a parent zeolite (BEA, FAU), reducing them with H2 to form metal clusters, and transforming these zeolites into daughter structures of higher framework density (MFI) under hydrothermal conditions. These transformations required MFI seeds or organic templates for FAU parent zeolites, but not for BEA, and occurred with the retention of encapsulated clusters. Clusters uniform in size (1.3-1.7 nm) and exposing clean and accessible surfaces formed in BEA and FAU zeolites; their size remained essentially unchanged upon transformation into MFI. Encapsulation selectivities, determined from the relative hydrogenation rates of small (toluene) and large (alkyl arenes) molecules and defined as the ratio of the surface areas of all the clusters in the sample to that of external clusters, were very high (8.1-40.9) for both parent and daughter zeolites. Encapsulation into MFI via direct hydrothermal syntheses was unsuccessful because metal precursors precipitated prematurely at the pH and temperatures required for MFI synthesis. Delayed introduction of metal precursors and F(-) (instead of OH(-)) as the mineralizing agent in hydrothermal syntheses increased encapsulation selectivities, but they remained lower than those achieved via interzeolite transformations. These interconversions provide a general and robust strategy for encapsulation of metals when precursors can be introduced via exchange into a zeolite that can be transformed into target daughter zeolites with higher framework densities, whether spontaneously or by using seeds or structure-directing agents (SDA).

  4. Efficiently determining transform filter coefficients for image processing by applying distributed genetic algorithms

    NASA Astrophysics Data System (ADS)

    Gilligan, Martin; Lamont, Gary B.; Peterson, Michael R.

    2009-05-01

    An important aspect of contemporary military communications in the design of robust image transforms for defense surveillance applications. In particular, efficient yet effective transfer of critical image information is required for decision making. The generic use of wavelets to transform an image is a standard transform approach. However, the resulting bandwidth requirements can be quite high, suggesting that a different bandwidth-limited transform be developed. Thus, our specific use of genetic algorithms (GAs) attempts to replace standard wavelet filter coefficients with an optimized transform filter in order to retain or improve image quality for bandwidth-restricted surveillance applications. To find improved coefficients efficiently, we have developed a software engineered distributed design employing a genetic algorithm (GA) parallel island model on small and large computational clusters with multi-core nodes. The main objective is to determine whether running a distributed GA with multiple islands would either give statistically equivalent results quicker or obtain better results in the same amount of time. In order to compare computational performance with our previous serial results, we evaluate the obtained "optimal" wavelet coefficients on test images from both approaches which results in excellent comparative metric values.

  5. Experimental determination of the MHD-EMP effects on power distribution transformers

    SciTech Connect

    McConnell, B.W.; Barnes, P.R. ); Tesche, F.M. , Dallas, TX )

    1991-01-01

    It is a well-established fact that geomagnetic storms influence electrical power transmission and distribution systems. Previous cases of such storms in the northern latitudes have resulted in occasional power disruptions, and in some cases, damage to transformers. These effects are caused by a time variation of the earth's magnetic field creating an induced electric field along the surface of the earth. This E-field acts as a voltage source along long power transmission or distribution lines, and if the line is connected to the earth at both ends, a quasi-dc current can flow. This current can cause unwanted saturation in the magnetic cores of transformers in the power system, and this, in turn produces harmonic distortion and transformer heating. This can lead to system upset (shutdown) and possibly transformer burn-out. The detonation of a high altitude nuclear explosion is also known to affect the magnetosphere, producing late-time variations of the earth's magnetic field for several hundreds of seconds. Known as the magnetohydrodynamic electromagnetic pulse (MHD-EMP), or E{sub 3}, this environment is of particular concern to electrical power systems in the event of a nuclear attack. Although the MHD-EMP induced currents can be significantly larger in magnitude, they last for a shorter period of time than do those from a geomagnetic storm. The effect of this environment compounds the adverse effects of the early-time high altitude EMP (HEMP) environment, posing a potentially serious threat to the electrical system. The present paper documents an experimental program designed to better understand the behavior of distribution-class transformers subjected to quasi-dc current excitation. Given the knowledge of the MHD-EMP-induced current flowing in a long power line, and the transformer response characteristics obtained in this program, it will be possible to make more accurate assessments of the behavior of the overall power system to EMP. 7 refs., 5 figs.

  6. A distributed parameter model of transmission line transformer for high voltage nanosecond pulse generation

    NASA Astrophysics Data System (ADS)

    Li, Jiangtao; Zhao, Zheng; Li, Longjie; He, Jiaxin; Li, Chenjie; Wang, Yifeng; Su, Can

    2017-09-01

    A transmission line transformer has potential advantages for nanosecond pulse generation including excellent frequency response and no leakage inductance. The wave propagation process in a secondary mode line is indispensable due to an obvious inside transient electromagnetic transition in this scenario. The equivalent model of the transmission line transformer is crucial for predicting the output waveform and evaluating the effects of magnetic cores on output performance. However, traditional lumped parameter models are not sufficient for nanosecond pulse generation due to the natural neglect of wave propagations in secondary mode lines based on a lumped parameter assumption. In this paper, a distributed parameter model of transmission line transformer was established to investigate wave propagation in the secondary mode line and its influential factors through theoretical analysis and experimental verification. The wave propagation discontinuity in the secondary mode line induced by magnetic cores is emphasized. Characteristics of the magnetic core under a nanosecond pulse were obtained by experiments. Distribution and formation of the secondary mode current were determined for revealing essential wave propagation processes in secondary mode lines. The output waveform and efficiency were found to be affected dramatically by wave propagation discontinuity in secondary mode lines induced by magnetic cores. The proposed distributed parameter model was proved more suitable for nanosecond pulse generation in aspects of secondary mode current, output efficiency, and output waveform. In depth, comprehension of underlying mechanisms and a broader view of the working principle of the transmission line transformer for nanosecond pulse generation can be obtained through this research.

  7. [Metabolism, transformation and distribution of Coptis chinensis total alkaloids in rat].

    PubMed

    Wang, Liang; Ye, Xiaoli; Li, Xuegang; Chen, Zhu; Chen, Xiaodan; Gao, Ying; Zhao, Zhongqi; Huang, Wenwen; Chen, Xin; Yi, Jun

    2010-08-01

    To determine the pharmacokinetics, distribution and mutual transformation of the total alkaloids, jatrorrhizine, coptisine, berberine and palmatine from Coptis chinensis in rats. After the total alkaloids and berberine were fed into rats, their contents in plasma, tissues and gastrointestinal tract were determined by reversed-phase HPLC. The peak times of berberine in blood were 2.0 h (Cmax 3.7 mg x L(-1)) and 5.0 h Cmax 2.8 mg x L(-1)), respectively. Berberine in rat blood can be transformed into jatrorrhizine. After the rats were fed with the total alkaloids by gavage, the content of berberine was decreased monotonously, while coptisine, palmatine and jatrorrhizine contents were increased gradually in the stomach, it speculated that berberine may be transformed into jatrorrhizine in the stomach. Animal experiments showed that berberine and palmatine were mainly distributed in the lungs of animals, followed by the distribution in the liver, while jatrorrhizine and coptisine was mainly in the liver, then in the lungs. Berberine could transform into jatrorrhizine. The mechanism on the appearance of two maximum blood concentration of berberine in blood could be explained with the propulsion of the gastrointestinal tract partly.

  8. On the twisted convolution product and the Weyl transformation of tempered distributions

    NASA Astrophysics Data System (ADS)

    Maillard, J. M.

    It is well known that the Weyl transformation in a phase space R21, transforms the elements of L( R21) in trace class operators and the elements of L 2( R21) in the Hilbert-Schmidt operators of the Hilbert space L 2( R1); this fact leads to a general method of quantization suggested by E. Wigner and J.E. Moyal and developed by M. Flato, A. Lichnerowicz, C. Fronsdal, D. Sternheimer and F. Bayen for an arbitrary symplectic manifold, known under the name of star-product method. In this context, it is important to study the Weyl transforms of the tempered distributions on the phase space and that of the star-exponentials which gave the spectrum in this process of quantization. We analyze here the relations between the star-product, the twisted convolution product and the Weyl transformation of tempered distributions. We introduce symplectic differential operators which permit us to study the structure of the space O1λ λ ≠ 0, (similar to the space O1C) of the left (twisted) convolution operators of L( R21) which permit to define the twisted convolution product in the space L( R21), and the structures of the admissible symbols for the Weyl transformation (i.e. the domain of the Weyl transformation). We prove that the bounded operators of L 2( R1) are exactly the Weyl transforms of the bounded (twisted) convolution operators of L 2( R21). We give an expression of the integral formula of the star product in terms of twisted convolution products which is valid in the most general case. The unitary representations of the Heisenberg group play an important role here.

  9. A Curious Lack of Evolution in the LGRB Host Metallicity Distribution

    NASA Astrophysics Data System (ADS)

    Graham, John; Schady, Patricia; Kruehler, Thomas

    2017-01-01

    Recent improvements in the population of Long-duration Gamma Ray Burst host galaxies with measured metallicities and host masses allows us to investigate how the distributions of both these properties change with redshift. First we examine possible biases in the populations caused by the efficiency of obtaining mass and metallicity measurements at different redshifts. In comparing the redshift distributions of a variety of LGRB populations we find no biases out to a redshift of 2.5 with the exception of a reduced metallicity sampling at redshifts high enough to require a separate IR spectrum (z < 0.5). However observations using X-shooter (which allow for obtaining metallicities across a wide range of redshifts) do not show this bias. We also compare the observed LGRB redshift distribution with recent predictions and find good agreement. Having established that the mass and metallicity samples are unbiased we then find a curious consistency in the metallicity destruction across different redshifts. This is at odds with the general evolution in the mass metallicity relation, which becomes progressively more metal poor with increasing redshift. We do however find that the LGRB host galaxy mass distribution increases with redshift so as to preserve the LGRB metallicity destruction. In fact, converting the measured LGRB host masses to their expected metallicities reproduces reasonably consistent metallicity distribution.

  10. A globally distributed mobile genetic element inhibits natural transformation of Vibrio cholerae

    PubMed Central

    Dalia, Ankur B.; Seed, Kimberley D.; Calderwood, Stephen B.; Camilli, Andrew

    2015-01-01

    Natural transformation is one mechanism of horizontal gene transfer (HGT) in Vibrio cholerae, the causative agent of cholera. Recently, it was found that V. cholerae isolates from the Haiti outbreak were poorly transformed by this mechanism. Here, we show that an integrating conjugative element (ICE)-encoded DNase, which we name IdeA, is necessary and sufficient for inhibiting natural transformation of Haiti outbreak strains. We demonstrate that IdeA inhibits this mechanism of HGT in cis via DNA endonuclease activity that is localized to the periplasm. Furthermore, we show that natural transformation between cholera strains in a relevant environmental context is inhibited by IdeA. The ICE encoding IdeA is globally distributed. Therefore, we analyzed the prevalence and role for this ICE in limiting natural transformation of isolates from Bangladesh collected between 2001 and 2011. We found that IdeA+ ICEs were nearly ubiquitous in isolates from 2001 to 2005; however, their prevalence decreased to ∼40% from 2006 to 2011. Thus, IdeA+ ICEs may have limited the role of natural transformation in V. cholerae. However, the rise in prevalence of strains lacking IdeA may now increase the role of this conserved mechanism of HGT in the evolution of this pathogen. PMID:26240317

  11. Transform-limited pulses generated by an actively Q-switched distributed fiber laser.

    PubMed

    Cuadrado-Laborde, C; Pérez-Millán, P; Andrés, M V; Díez, A; Cruz, J L; Barmenkov, Yu O

    2008-11-15

    A single-mode, transform-limited, actively Q-switched distributed-feedback fiber laser is presented, based on a new in-line acoustic pulse generator. Our technique permits a continuous adjustment of the repetition rate that modulates the Q factor of the cavity. Optical pulses of 800 mW peak power, 32 ns temporal width, and up to 20 kHz repetition rates were obtained. The measured linewidth demonstrates that these pulses are transform limited: 6 MHz for a train of pulses of 10 kHz repetition rate, 80 ns temporal width, and 60 mW peak power. Efficient excitation of spontaneous Brillouin scattering is demonstrated.

  12. TRANSFORMER

    DOEpatents

    Baker, W.R.

    1959-08-25

    Transformers of a type adapted for use with extreme high power vacuum tubes where current requirements may be of the order of 2,000 to 200,000 amperes are described. The transformer casing has the form of a re-entrant section being extended through an opening in one end of the cylinder to form a coaxial terminal arrangement. A toroidal multi-turn primary winding is disposed within the casing in coaxial relationship therein. In a second embodiment, means are provided for forming the casing as a multi-turn secondary. The transformer is characterized by minimized resistance heating, minimized external magnetic flux, and an economical construction.

  13. Controllable Phase Transformation in Extracting Valuable Metals from Chinese Low-Grade Nickel Sulphide Ore

    NASA Astrophysics Data System (ADS)

    Cui, Fuhui; Mu, Wenning; Wang, Shuai; Xu, Qian; Zhai, Yuchun; Luo, Shaohua

    2017-10-01

    In this work, a two-stage sulphuric acid roasting and water leaching system was chosen to extract valuable metals from Chinese low-grade nickel sulphide ore. By optimizing the two-stage roasting process, first roasting temperature at 295°C with particle size of 80-91 μm with an acid-ore ratio of 1.1:1 for 2 h, and second roasting temperature at 620°C for 2 h, it was found that more than 98% of the nickel and 99% of the copper but less than 14.38% of Fe were leached into the water. Attempts were made via x-ray diffraction analysis, scanning electron microscopy, chemical phase analysis, and differential thermal and thermogravimetric analysis to reveal the phase transformations for Ni, Cu, and Mg, which could be expressed as mineral phases → sulphates hydrate → sulphates and for iron as mineral phases → hydrated ferrous sulphate → ferric sulphates and ferric oxide → oxide. The results of this work suggest that a controllable phase transformation by using a two-stage sulphuric acid roasting process is a feasible method for efficiently extracting valuable metals from Chinese nickel sulphide ore.

  14. Abnormal correlation between phase transformation and cooling rate for pure metals

    PubMed Central

    Han, J. J.; Wang, C. P.; Liu, X. J.; Wang, Y.; Liu, Z.-K.; Zhang, T.-Y.; Jiang, J. Z.

    2016-01-01

    This work aims to achieve deep insight into the phenomenon of phase transformation upon rapid cooling in metal systems and reveal the physical meaning of scatter in the time taken to reach crystallization. The total number of pure metals considered in this work accounts for 14. Taking pure copper as an example, the correlation between phase selection of crystal or glass and cooling rate was investigated using molecular dynamic simulations. The obtained results demonstrate that there exists a cooling rate region of 6.3 × 1011–16.6 × 1011 K/s, in which crystalline fractions largely fluctuate along with cooling rates. Glass transformation in this cooling rate region is determined by atomic structure fluctuation, which is controlled by thermodynamic factors. According to the feature of bond-orientation order at different cooling rates, we propose two mechanisms of glass formation: (i) kinetic retardation of atom rearrangement or structural relaxation at a high cooling rate; and (ii) competition of icosahedral order against crystal order near the critical cooling rate. PMID:26939584

  15. Abnormal correlation between phase transformation and cooling rate for pure metals.

    PubMed

    Han, J J; Wang, C P; Liu, X J; Wang, Y; Liu, Z-K; Zhang, T-Y; Jiang, J Z

    2016-03-04

    This work aims to achieve deep insight into the phenomenon of phase transformation upon rapid cooling in metal systems and reveal the physical meaning of scatter in the time taken to reach crystallization. The total number of pure metals considered in this work accounts for 14. Taking pure copper as an example, the correlation between phase selection of crystal or glass and cooling rate was investigated using molecular dynamic simulations. The obtained results demonstrate that there exists a cooling rate region of 6.3 × 10(11)-16.6 × 10(11) K/s, in which crystalline fractions largely fluctuate along with cooling rates. Glass transformation in this cooling rate region is determined by atomic structure fluctuation, which is controlled by thermodynamic factors. According to the feature of bond-orientation order at different cooling rates, we propose two mechanisms of glass formation: (i) kinetic retardation of atom rearrangement or structural relaxation at a high cooling rate; and (ii) competition of icosahedral order against crystal order near the critical cooling rate.

  16. Metal-induced rapid transformation of diamond into single and multilayer graphene on wafer scale

    DOE PAGES

    Berman, Diana; Deshmukh, Sanket; Narayanan, Badri; ...

    2016-07-04

    The degradation of intrinsic properties of graphene during the transfer process constitutes a major challenge in graphene device fabrication, stimulating the need for direct growth of graphene on dielectric substrates. Previous attempts of metal-induced transformation of diamond and silicon carbide into graphene suffers from metal contamination and inability to scale graphene growth over large area. Here in this article, we introduce a direct approach to transform polycrystalline diamond into high-quality graphene layers on wafer scale (4 inch in diameter) using a rapid thermal annealing process facilitated by a nickel, Ni thin film catalyst on top. We show that the processmore » can be tuned to grow single or multilayer graphene with good electronic properties. Molecular dynamics simulations elucidate the mechanism of graphene growth on polycrystalline diamond. Additionally, we demonstrate the lateral growth of free-standing graphene over micron-sized pre-fabricated holes, opening exciting opportunities for future graphene/diamond-based electronics.« less

  17. Controllable Phase Transformation in Extracting Valuable Metals from Chinese Low-Grade Nickel Sulphide Ore

    NASA Astrophysics Data System (ADS)

    Cui, Fuhui; Mu, Wenning; Wang, Shuai; Xu, Qian; Zhai, Yuchun; Luo, Shaohua

    2017-06-01

    In this work, a two-stage sulphuric acid roasting and water leaching system was chosen to extract valuable metals from Chinese low-grade nickel sulphide ore. By optimizing the two-stage roasting process, first roasting temperature at 295°C with particle size of 80-91 μm with an acid-ore ratio of 1.1:1 for 2 h, and second roasting temperature at 620°C for 2 h, it was found that more than 98% of the nickel and 99% of the copper but less than 14.38% of Fe were leached into the water. Attempts were made via x-ray diffraction analysis, scanning electron microscopy, chemical phase analysis, and differential thermal and thermogravimetric analysis to reveal the phase transformations for Ni, Cu, and Mg, which could be expressed as mineral phases → sulphates hydrate → sulphates and for iron as mineral phases → hydrated ferrous sulphate → ferric sulphates and ferric oxide → oxide. The results of this work suggest that a controllable phase transformation by using a two-stage sulphuric acid roasting process is a feasible method for efficiently extracting valuable metals from Chinese nickel sulphide ore.

  18. Homogeneous and Heterogeneous Reaction and Transformation of Hg and Trace Metals in Combustion Systems

    SciTech Connect

    J. Helble; Clara Smith; David Miller

    2009-08-31

    The overall goal of this project was to produce a working dynamic model to predict the transformation and partitioning of trace metals resulting from combustion of a broad range of fuels. The information provided from this model will be instrumental in efforts to identify fuels and conditions that can be varied to reduce metal emissions. Through the course of this project, it was determined that mercury (Hg) and arsenic (As) would be the focus of the experimental investigation. Experiments were therefore conducted to examine homogeneous and heterogeneous mercury oxidation pathways, and to assess potential interactions between arsenic and calcium. As described in this report, results indicated that the role of SO{sub 2} on Hg oxidation was complex and depended upon overall gas phase chemistry, that iron oxide (hematite) particles contributed directly to heterogeneous Hg oxidation, and that As-Ca interactions occurred through both gas-solid and within-char reaction pathways. Modeling based on this study indicated that, depending upon coal type and fly ash particle size, vaporization-condensation, vaporization-surface reaction, and As-CaO in-char reaction all play a role in arsenic transformations under combustion conditions.

  19. Impact of quasi-dc currents on three-phase distribution transformer installations

    SciTech Connect

    McConnell, B.W.; Barnes, P.R. ); Tesche, F.M. , Dallas, TX ); Schafer, D.A. )

    1992-06-01

    This report summarizes a series of tests designed to determine the response of quasi-dc currents on three-phase power distribution transformers for electric power systems. In general, if the dc injection is limited to the primary side of a step-down transformer, significant harmonic distortion is noted and an increase in the reactive power demand results. For dc injection on the secondary (load) side of the step-down transformer the harmonic content at the secondary side is quite high and saturation occurs with a relatively low level of dc injection; however, the reactive power demand is significantly lower. These tests produced no apparent damage to the transformers. Transformer damage is dependent on the duration of the dc excitation, the level of the excitation, and on thermal characteristics of the transfer. The transformer response time is found to be much shorter than seen in power transformer tests at lower dc injection levels. This shorter response time suggests that the response time is strongly dependent on the injected current levels, and that higher levels of dc injection for shorter durations could produce very high reactive power demands and harmonic distortion within a few tenths of a second. The added reactive power load could result in the blowing of fuses on the primary side of the transformer for even moderate dc injection levels, and neutral currents are quite large under even low-level dc injection. This smoking neutral'' results in high-level harmonic injection into equipment via the neutral and in possible equipment failure.

  20. Spatially resolved surface valence gradient and structural transformation of lithium transition metal oxides in lithium-ion batteries.

    PubMed

    Liu, Hanshuo; Bugnet, Matthieu; Tessaro, Matteo Z; Harris, Kristopher J; Dunham, Mark J R; Jiang, Meng; Goward, Gillian R; Botton, Gianluigi A

    2016-10-26

    Layered lithium transition metal oxides are one of the most important types of cathode materials in lithium-ion batteries (LIBs) that possess high capacity and relatively low cost. Nevertheless, these layered cathode materials suffer structural changes during electrochemical cycling that could adversely affect the battery performance. Clear explanations of the cathode degradation process and its initiation, however, are still under debate and not yet fully understood. We herein systematically investigate the chemical evolution and structural transformation of the LiNixMnyCo1-x-yO2 (NMC) cathode material in order to understand the battery performance deterioration driven by the cathode degradation upon cycling. Using high-resolution electron energy loss spectroscopy (HR-EELS) we clarify the role of transition metals in the charge compensation mechanism, particularly the controversial Ni(2+) (active) and Co(3+) (stable) ions, at different states-of-charge (SOC) under 4.6 V operation voltage. The cathode evolution is studied in detail from the first-charge to long-term cycling using complementary diagnostic tools. With the bulk sensitive (7)Li nuclear magnetic resonance (NMR) measurements, we show that the local ordering of transition metal and Li layers (R3[combining macron]m structure) is well retained in the bulk material upon cycling. In complement to the bulk measurements, we locally probe the valence state distribution of cations and the surface structure of NMC particles using EELS and scanning transmission electron microscopy (STEM). The results reveal that the surface evolution of NMC is initiated in the first-charging step with a surface reduction layer formed at the particle surface. The NMC surface undergoes phase transformation from the layered structure to a poor electronic and ionic conducting transition-metal oxide rock-salt phase (R3[combining macron]m → Fm3[combining macron]m), accompanied by irreversible lithium and oxygen loss. In addition to the

  1. [Influence of sulfur on the speciation transformation and phyto-availability of heavy metals in soil: a review].

    PubMed

    Sun, Li-Juan; Duan, De-Chao; Peng, Cheng; He, Jun-Yu; Shi, Ji-Yan

    2014-07-01

    The biogeochemical cycle of sulfur can directly affect the speciation transformation of heavy metals in soils and their accumulation in plants. The toxicity of heavy metals in plants can be alleviated by their complexation with sulfur compounds like phytochelatins or metallothiones, consisting of the major mechanisms of phytodetoxification. Sulfur deficiency is becoming one of the limiting factors that influence Chinese agricultural production. Although the applications of sulfur fertilizer in soil have received much attention in recent years, the interaction mechanism of heavy metal with sulfur metabolism has not been studied extensively. In this paper, we reviewed current research advance on the impact of sulfur on the speciation transformation of soil heavy metals and their accumulation in plants, discussed the effect of sulfur on the detoxification mechanism of heavy metal in plants and provided further research prospective in this field.

  2. Intermediate-range order in simple metal-phosphate glasses: The effect of metal cations on the phosphate anion distribution

    SciTech Connect

    Sales, B.C.; Boatner, L.A.; Ramey, J.O.

    1997-06-01

    The technique of high-performance liquid chromatography (HPLC) has been used to probe the phosphate anion distribution in a variety of metal phosphate glasses including glasses made with trivalent metal cations (Al, In, Ga, La). The composition of each glass was chosen so that the average phosphate chain length was between 2 and 4 PO{sub 4} tetrahedra. The widths of the resulting phosphate anion distributions were determined directly from an analysis of the HPLC chromatograms. Literature values for the free energy of formation of the crystalline metal-orthophosphate compounds with respect to P{sub 2}O{sub 5} and the metal oxide, were compared to the chromatogram widths. It was found that the smaller the energy of formation, the wider the distribution of phosphate chains, and the greater the ease of glass formation.

  3. Metal distribution and spectroscopic analysis after soil washing with chelating agents and humic substances.

    PubMed

    Tsang, Daniel C W; Hartley, Neil R

    2014-03-01

    Biodegradable chelating agents ([S,S]-ethylenediamine-N,N-disuccinic acid (EDDS) and glutamic-N,N-diacetic acid (GLDA)) and natural humic substances (lignite-derived, standard, and commercially available humic acids) are potentially useful for enhancing soil remediation of timber treatment sites. This study integrated macroscopic and spectroscopic analyses to assess their influence on the distribution and chemical speciation of the remaining metals as well as their interaction with the soil surface after 48-h washing of a field-contaminated soil. The results demonstrated that EDDS and GLDA were an appealing alternative to non-biodegradable ethylenediamine-tetraacetic acid, but the three humic substances were less effective. As shown by sequential extractions, Cu was primarily extracted from the carbonate fraction while Cr and As extraction resulted from (co-)dissolution of the oxide fraction. As a result, the relative proportion of strongly bound organic matter and residual fractions increased by 7-16 %. However, it was noteworthy that the exchangeable fraction also increased by 5-11 %, signifying that a portion of the remaining metals was destabilized by chelating agents and transformed to be more labile in the treated soil. The X-ray photoelectron spectroscopy spectra confirmed the substantial removal of readily accessible Cu from the soil surface, but Cr maintained its original chemical forms of trivalent chromium oxides and iron-chromium coprecipitates, whereas As remained as arsenic trioxide/pentoxide and copper arsenate precipitates. On the other hand, the absence of characteristic peaks of adsorbed carboxylate groups in the Fourier-transform infrared (FTIR) spectra inferred that the extent of adsorption of chelating agents and humic substances on the bulk soil was insufficient to be characterized by FTIR analysis. These results suggested that attention should be paid to the exchangeable fraction of Cu and oxides/coprecipitates of As prior to possible on

  4. Laccase-mediated transformation of triclosan in aqueous solution with metal cations and humic acid.

    PubMed

    Sun, Kai; Kang, Fuxing; Waigi, Michael Gatheru; Gao, Yanzheng; Huang, Qingguo

    2017-01-01

    Triclosan (TCS) is a broad-spectrum antimicrobial agent that is found extensively in natural aquatic environments. Enzyme-catalyzed oxidative coupling reactions (ECOCRs) can be used to remove TCS in aqueous solution, but there is limited information available to indicate how metal cations (MCs) and natural organic matter (NOM) influence the environmental fate of TCS during laccase-mediated ECOCRs. In this study, we demonstrated that the naturally occurring laccase from Pleurotus ostreatus was effective in removing TCS during ECOCRs, and the oligomerization of TCS was identified as the dominant reaction pathway by high-resolution mass spectrometry (HRMS). The growth inhibition studies of green algae (Chlamydomonas reinhardtii and Scenedesmus obliquus) proved that laccase-mediated ECOCRs could effectively reduce the toxicity of TCS. The presence of dissolved MCs (Mn(2+), Al(3+), Ca(2+), Cu(2+), and Fe(2+) ions) influenced the removal and transformation of TCS via different mechanisms. Additionally, the transformation of TCS in systems with NOM derived from humic acid (HA) was hindered, and the apparent pseudo first-order kinetics rate constants (k) for TCS decreased as the HA concentration increased, which likely corresponded to the combined effect of both noncovalent (sorption) and covalent binding between TCS and humic molecules. Our results provide a novel insight into the fate and transformation of TCS by laccase-mediated ECOCRs in natural aquatic environments in the presence of MCs and NOM. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. THE MOST METAL-POOR STARS. III. THE METALLICITY DISTRIBUTION FUNCTION AND CARBON-ENHANCED METAL-POOR FRACTION , ,

    SciTech Connect

    Yong, David; Norris, John E.; Bessell, M. S.; Asplund, M.; Christlieb, N.; Beers, Timothy C.; Barklem, P. S.; Frebel, Anna; Ryan, S. G. E-mail: jen@mso.anu.edu.au E-mail: martin@mso.anu.edu.au E-mail: beers@pa.msu.edu E-mail: afrebel@mit.edu

    2013-01-01

    We examine the metallicity distribution function (MDF) and fraction of carbon-enhanced metal-poor (CEMP) stars in a sample that includes 86 stars with [Fe/H] {<=} -3.0, based on high-resolution, high signal-to-noise spectroscopy, of which some 32 objects lie below [Fe/H] = -3.5. After accounting for the completeness function, the 'corrected' MDF does not exhibit the sudden drop at [Fe/H] = -3.6 that was found in recent samples of dwarfs and giants from the Hamburg/ESO survey. Rather, the MDF decreases smoothly down to [Fe/H] = -4.1. Similar results are obtained from the 'raw' MDF. We find that the fraction of CEMP objects below [Fe/H] = -3.0 is 23% {+-} 6% and 32% {+-} 8% when adopting the Beers and Christlieb and Aoki et al. CEMP definitions, respectively. The former value is in fair agreement with some previous measurements, which adopt the Beers and Christlieb criterion.

  6. A biomonitoring study of genotoxic risk to workers of transformers and distribution line stations.

    PubMed

    Celikler, Serap; Aydemir, Nilufer; Vatan, Ozgur; Kurtuldu, Sevim; Bilaloglu, Rahmi

    2009-12-01

    A cytogenetic monitoring study was carried out on a group of workers from transformer and distribution line stations in the Bursa province of Turkey, to investigate the genotoxic risk of occupational exposure to extremely low frequency electric (ELF) and magnetic fields (EMF). Cytogenetic analysis, namely chromosomal aberrations (CAs) and micronucleus (MN) tests were performed on a strictly selected group of 55 workers and compared to 17 controls. CA and MN frequencies in electrical workers appeared significantly higher than in controls (p < 0.001, 0.05, respectively). The frequency of CA in exposed groups were significantly enhanced with the years of exposure (p < 0.01). The effect of smoking on the level of CA and MN was not significant in the control and exposure groups. The results of this study demonstrated that a significant induction of cytogenetic damage in peripheral lymphocytes of workers engaged to occupational exposure to ELMF in electric transformer and distribution stations.

  7. Number density distribution of solvent molecules on a substrate: a transform theory for atomic force microscopy.

    PubMed

    Amano, Ken-Ichi; Liang, Yunfeng; Miyazawa, Keisuke; Kobayashi, Kazuya; Hashimoto, Kota; Fukami, Kazuhiro; Nishi, Naoya; Sakka, Tetsuo; Onishi, Hiroshi; Fukuma, Takeshi

    2016-06-21

    Atomic force microscopy (AFM) in liquids can measure a force curve between a probe and a buried substrate. The shape of the measured force curve is related to hydration structure on the substrate. However, until now, there has been no practical theory that can transform the force curve into the hydration structure, because treatment of the liquid confined between the probe and the substrate is a difficult problem. Here, we propose a robust and practical transform theory, which can generate the number density distribution of solvent molecules on a substrate from the force curve. As an example, we analyzed a force curve measured by using our high-resolution AFM with a newly fabricated ultrashort cantilever. It is demonstrated that the hydration structure on muscovite mica (001) surface can be reproduced from the force curve by using the transform theory. The transform theory will enhance AFM's ability and support structural analyses of solid/liquid interfaces. By using the transform theory, the effective diameter of a real probe apex is also obtained. This result will be important for designing a model probe of molecular scale simulations.

  8. A Conserved Metal Binding Motif in the Bacillus subtilis Competence Protein ComFA Enhances Transformation.

    PubMed

    Chilton, Scott S; Falbel, Tanya G; Hromada, Susan; Burton, Briana M

    2017-08-01

    Genetic competence is a process in which cells are able to take up DNA from their environment, resulting in horizontal gene transfer, a major mechanism for generating diversity in bacteria. Many bacteria carry homologs of the central DNA uptake machinery that has been well characterized in Bacillus subtilis It has been postulated that the B. subtilis competence helicase ComFA belongs to the DEAD box family of helicases/translocases. Here, we made a series of mutants to analyze conserved amino acid motifs in several regions of B. subtilis ComFA. First, we confirmed that ComFA activity requires amino acid residues conserved among the DEAD box helicases, and second, we show that a zinc finger-like motif consisting of four cysteines is required for efficient transformation. Each cysteine in the motif is important, and mutation of at least two of the cysteines dramatically reduces transformation efficiency. Further, combining multiple cysteine mutations with the helicase mutations shows an additive phenotype. Our results suggest that the helicase and metal binding functions are two distinct activities important for ComFA function during transformation.IMPORTANCE ComFA is a highly conserved protein that has a role in DNA uptake during natural competence, a mechanism for horizontal gene transfer observed in many bacteria. Investigation of the details of the DNA uptake mechanism is important for understanding the ways in which bacteria gain new traits from their environment, such as drug resistance. To dissect the role of ComFA in the DNA uptake machinery, we introduced point mutations into several motifs in the protein sequence. We demonstrate that several amino acid motifs conserved among ComFA proteins are important for efficient transformation. This report is the first to demonstrate the functional requirement of an amino-terminal cysteine motif in ComFA. Copyright © 2017 American Society for Microbiology.

  9. Entropy-based heavy tailed distribution transformation and visual analytics for monitoring massive network traffic

    NASA Astrophysics Data System (ADS)

    Han, Keesook J.; Hodge, Matthew; Ross, Virginia W.

    2011-06-01

    For monitoring network traffic, there is an enormous cost in collecting, storing, and analyzing network traffic datasets. Data mining based network traffic analysis has a growing interest in the cyber security community, but is computationally expensive for finding correlations between attributes in massive network traffic datasets. To lower the cost and reduce computational complexity, it is desirable to perform feasible statistical processing on effective reduced datasets instead of on the original full datasets. Because of the dynamic behavior of network traffic, traffic traces exhibit mixtures of heavy tailed statistical distributions or overdispersion. Heavy tailed network traffic characterization and visualization are important and essential tasks to measure network performance for the Quality of Services. However, heavy tailed distributions are limited in their ability to characterize real-time network traffic due to the difficulty of parameter estimation. The Entropy-Based Heavy Tailed Distribution Transformation (EHTDT) was developed to convert the heavy tailed distribution into a transformed distribution to find the linear approximation. The EHTDT linearization has the advantage of being amenable to characterize and aggregate overdispersion of network traffic in realtime. Results of applying the EHTDT for innovative visual analytics to real network traffic data are presented.

  10. Efficient packing Fourier-transform approach for ultrahigh resolution isotopic distribution calculations.

    PubMed

    Fernandez-de-Cossio, Jorge

    2010-03-01

    Fine isotopic structure patterns resolvable by ultrahigh-resolution mass spectrometers are diagnostic of the elemental composition of moderately large compounds. Despite the proven performance of Fourier transforms algorithms to calculate accurate high resolution isotopic distribution, its application to finer ultrahigh resolving power exhibits limited performance. Fast Fourier transforms algorithm requires sampling the relevant range at equally spaced mass values, but ultrahigh resolution mass spectrum displays highly localized complex patterns (peaks) separated in between by relatively large unstructured intervals. Computational efforts consumed on those uninformative intervals are a waste of resources. A fast and memory efficient procedure is introduced in this paper to calculate the isotopic distribution of a single relatively high-mass molecule at ultrahigh resolution by Fourier transforms approaches. The whole isotopic distribution is packed closer to the monoisotopic peak without distorting the actual scale of the peak fine structure. This packing procedure reduced 8 to 32 times the computation resources in comparison to the same calculation performed without packing. The procedure can be readily implemented in existing software.

  11. Spatial variance of POPs and heavy metals in transformer oil-contaminated soil around Tamil Nadu.

    PubMed

    Murugan, Karuvelan; Vasudevan, Namasivayam

    2017-09-05

    The persistent organic pollutants in the environment are one of the global issues to their unregulated disposal and informal recycling. This study investigates the contamination of soil with polychlorinated biphenyls (PCBs), polyaromatic hydrocarbons (PAHs), phenolic compounds and heavy metals via spillage of transformer oil (TO). Fresh TO (FTO), used TO (UTO) and soil samples were analysed using GC-MS to confirm the presence of 8 PCB congeners, 16 PAHs and 24 types of phenolic compounds and using inductively coupled plasma optical emission spectrometry to confirm the presence of 7 heavy metals. The chromatographic analysis revealed the levels of mono-, di-, tri-, tetra-, penta-, hexa-, hepta- and octachlorobiphenyls in FTO to be 5.63, 25.24, 0.195, 0.185, 2.169, 1.023 and 5.28 mg/L and the level of mono-, di-, tri-, tetra-, penta- and hexachlorobiphenyls in UTO to be 0.27, 1.21, 1.31, 0.80, 1.77 and 3.90 mg/L. Analysis of soil from 10 different TO-contaminated sites showed the presence of PCBs, PAHs, phenolic compounds and heavy metals in the concentration range of 0.53-42.87 mg/kg, 3.19-246.6 μg/kg, 0.01-4086.45 μg/kg and 1.0-401.3 mg/kg, respectively. The variation in the concentration of these compounds and heavy metals among different sampling sites was determined using principal component analysis (PCA), metric multi-dimensional scaling (MDS) and Bray-Curtis cluster analysis (Bu-CA). The toxicity equivalence factor and the mechanism involved in the disruption of endocrine system are discussed. Thus, this study exemplifies the need for complete ban of PCB-containing TOs in developing countries and urges the need for technology for the disposal of TO.

  12. Transport and transformation of mercury during wet flue gas cleaning process of nonferrous metal smelting.

    PubMed

    Liu, Zhilou; Wang, Dongli; Peng, Bing; Chai, Liyuan; Liu, Hui; Yang, Shu; Yang, Bentao; Xiang, Kaisong; Liu, Cao

    2017-08-12

    Reducing mercury emission is hot topic for international society. The first step for controlling mercury in fuel gas is to investigate mercury distribution and during the flue gas treatment process. The mercury transport and transformation in wet flue gas cleaning process of nonferrous smelting industry was studied in the paper with critical important parameters, such as the solution temperature, Hg(0) concentration, SO2 concentration, and Hg(2+) concentration at the laboratory scale. The mass ratio of the mercury distribution in the solution, flue gas, sludge, and acid fog from the simulated flue gas containing Hg(2+) and Hg(0) was 49.12~65.54, 18.34~35.42, 11.89~14.47, and 1.74~3.54%, respectively. The primary mercury species in the flue gas and acid fog were gaseous Hg(0) and dissolved Hg(2+). The mercury species in the cleaning solution were dissolved Hg(2+) and colloidal mercury, which accounted for 56.56 and 7.34% of the total mercury, respectively. Various mercury compounds, including Hg2Cl2, HgS, HgCl2, HgSO4, and HgO, existed in the sludge. These results for mercury distribution and speciation are highly useful in understanding mercury transport and transformation during the wet flue gas cleaning process. This research is conducive for controlling mercury emissions from nonferrous smelting flue gas and by-products.

  13. Magnetostructural martensitic transformations with large volume changes and magneto-strains in all-d-metal Heusler alloys

    NASA Astrophysics Data System (ADS)

    Wei, Z. Y.; Liu, E. K.; Li, Y.; Han, X. L.; Du, Z. W.; Luo, H. Z.; Liu, G. D.; Xi, X. K.; Zhang, H. W.; Wang, W. H.; Wu, G. H.

    2016-08-01

    The all-d-metal Mn2-based Heusler ferromagnetic shape memory alloys Mn50Ni40-xCoxTi10 (x = 8 and 9.5) are realized. With a generic comparison between d-metal Ti and main-group elements in lowering the transformation temperature, the magnetostructural martensitic transformations are established by further introducing Co to produce local ferromagnetic Mn-Co-Mn configurations. A 5-fold modulation and (3, -2) stacking of [00 10] of martensite are determined by X-ray diffraction and HRTEM analysis. Based on the transformation, a large magneto-strain of 6900 ppm and a large volume change of -2.54% are observed in polycrystalline samples, which makes the all-d-metal magnetic martensitic alloys of interest for magnetic/pressure multi-field driven applications.

  14. Magnetostructural martensitic transformations with large volume changes and magneto-strains in all-d-metal Heusler alloys

    SciTech Connect

    Wei, Z. Y.; Liu, E. K. Xi, X. K.; Zhang, H. W.; Wang, W. H.; Wu, G. H.; Li, Y.; Han, X. L.; Du, Z. W.; Luo, H. Z.; Liu, G. D.

    2016-08-15

    The all-d-metal Mn{sub 2}-based Heusler ferromagnetic shape memory alloys Mn{sub 50}Ni{sub 40−x}Co{sub x}Ti{sub 10} (x = 8 and 9.5) are realized. With a generic comparison between d-metal Ti and main-group elements in lowering the transformation temperature, the magnetostructural martensitic transformations are established by further introducing Co to produce local ferromagnetic Mn-Co-Mn configurations. A 5-fold modulation and (3, −2) stacking of [00 10] of martensite are determined by X-ray diffraction and HRTEM analysis. Based on the transformation, a large magneto-strain of 6900 ppm and a large volume change of −2.54% are observed in polycrystalline samples, which makes the all-d-metal magnetic martensitic alloys of interest for magnetic/pressure multi-field driven applications.

  15. Visualizing Metal Content and Intracellular Distribution in Primary Hippocampal Neurons with Synchrotron X-Ray Fluorescence

    PubMed Central

    2016-01-01

    Increasing evidence suggests that metal dyshomeostasis plays an important role in human neurodegenerative diseases. Although distinctive metal distributions are described for mature hippocampus and cortex, much less is known about metal levels and intracellular distribution in individual hippocampal neuronal somata. To solve this problem, we conducted quantitative metal analyses utilizing synchrotron radiation X-Ray fluorescence on frozen hydrated primary cultured neurons derived from rat embryonic cortex (CTX) and two regions of the hippocampus: dentate gyrus (DG) and CA1. Comparing average metal contents showed that the most abundant metals were calcium, iron, and zinc, whereas metals such as copper and manganese were less than 10% of zinc. Average metal contents were generally similar when compared across neurons cultured from CTX, DG, and CA1, except for manganese that was larger in CA1. However, each metal showed a characteristic spatial distribution in individual neuronal somata. Zinc was uniformly distributed throughout the cytosol, with no evidence for the existence of previously identified zinc-enriched organelles, zincosomes. Calcium showed a peri-nuclear distribution consistent with accumulation in endoplasmic reticulum and/or mitochondria. Iron showed 2–3 distinct highly concentrated puncta only in peri-nuclear locations. Notwithstanding the small sample size, these analyses demonstrate that primary cultured neurons show characteristic metal signatures. The iron puncta probably represent iron-accumulating organelles, siderosomes. Thus, the metal distributions observed in mature brain structures are likely the result of both intrinsic neuronal factors that control cellular metal content and extrinsic factors related to the synaptic organization, function, and contacts formed and maintained in each region. PMID:27434052

  16. Visualizing Metal Content and Intracellular Distribution in Primary Hippocampal Neurons with Synchrotron X-Ray Fluorescence

    DOE PAGES

    Colvin, Robert A.; Jin, Qiaoling; Lai, Barry; ...

    2016-07-19

    Increasing evidence suggests that metal dyshomeostasis plays an important role in human neurodegenerative diseases. Although distinctive metal distributions are described for mature hippocampus and cortex, much less is known about metal levels and intracellular distribution in individual hippocampal neuronal somata. To solve this problem, we conducted quantitative metal analyses utilizing synchrotron radiation X-Ray fluorescence on frozen hydrated primary cultured neurons derived from rat embryonic cortex (CTX) and two regions of the hippocampus: dentate gyrus (DG) and CA1. Also, comparing average metal contents showed that the most abundant metals were calcium, iron, and zinc, whereas metals such as copper and manganesemore » were less than 10% of zinc. Average metal contents were generally similar when compared across neurons cultured from CTX, DG, and CA1, except for manganese that was larger in CA1. However, each metal showed a characteristic spatial distribution in individual neuronal somata. Zinc was uniformly distributed throughout the cytosol, with no evidence for the existence of previously identified zinc-enriched organelles, zincosomes. Calcium showed a peri-nuclear distribution consistent with accumulation in endoplasmic reticulum and/or mitochondria. Iron showed 2-3 distinct highly concentrated puncta only in peri-nuclear locations. Notwithstanding the small sample size, these analyses demonstrate that primary cultured neurons show characteristic metal signatures. The iron puncta probably represent iron-accumulating organelles, siderosomes. Thus, the metal distributions observed in mature brain structures are likely the result of both intrinsic neuronal factors that control cellular metal content and extrinsic factors related to the synaptic organization, function, and contacts formed and maintained in each region.« less

  17. Application of Distribution Transformer Thermal Life Models to Electrified Vehicle Charging Loads Using Monte-Carlo Method: Preprint

    SciTech Connect

    Kuss, M.; Markel, T.; Kramer, W.

    2011-01-01

    Concentrated purchasing patterns of plug-in vehicles may result in localized distribution transformer overload scenarios. Prolonged periods of transformer overloading causes service life decrements, and in worst-case scenarios, results in tripped thermal relays and residential service outages. This analysis will review distribution transformer load models developed in the IEC 60076 standard, and apply the model to a neighborhood with plug-in hybrids. Residential distribution transformers are sized such that night-time cooling provides thermal recovery from heavy load conditions during the daytime utility peak. It is expected that PHEVs will primarily be charged at night in a residential setting. If not managed properly, some distribution transformers could become overloaded, leading to a reduction in transformer life expectancy, thus increasing costs to utilities and consumers. A Monte-Carlo scheme simulated each day of the year, evaluating 100 load scenarios as it swept through the following variables: number of vehicle per transformer, transformer size, and charging rate. A general method for determining expected transformer aging rate will be developed, based on the energy needs of plug-in vehicles loading a residential transformer.

  18. Influence of Transformation Plasticity on the Distribution of Internal Stress in Three Water-Quenched Cylinders

    NASA Astrophysics Data System (ADS)

    Liu, Yu; Qin, Shengwei; Zhang, Jiazhi; Wang, Ying; Rong, Yonghua; Zuo, Xunwei; Chen, Nailu

    2017-10-01

    Based on the hardenability of three medium carbon steels, cylinders with the same 60-mm diameter and 240-mm length were designed for quenching in water to obtain microstructures, including a pearlite matrix (Chinese steel mark: 45), a bainite matrix (42CrMo), and a martensite matrix (40CrNiMo). Through the combination of normalized functions describing transformation plasticity (TP), the thermo-elasto-plastic constitutive equation was deduced. The results indicate that the finite element simulation (FES) of the internal stress distribution in the three kinds of hardenable steel cylinders based on the proposed exponent-modified (Ex-Modified) normalized function is more consistent with the X-ray diffraction (XRD) measurements than those based on the normalized functions proposed by Abrassart, Desalos, and Leblond, which is attributed to the fact that the Ex-Modified normalized function better describes the TP kinetics. In addition, there was no significant difference between the calculated and measured stress distributions, even though TP was taken into account for the 45 carbon steel; that is, TP can be ignored in FES. In contrast, in the 42CrMo and 40CrNiMo alloyed steels, the significant effect of TP on the residual stress distributions was demonstrated, meaning that TP must be included in the FES. The rationality of the preceding conclusions was analyzed. The complex quenching stress is a consequence of interactions between the thermal and phase transformation stresses. The separated calculations indicate that the three steels exhibit similar thermal stress distributions for the same water-quenching condition, but different phase transformation stresses between 45 carbon steel and alloyed steels, leading to different distributions of their axial and tangential stresses.

  19. The development of coil short circuits when transformer windings become contaminated with metal-containing colloidal particles

    SciTech Connect

    L'vov, S. Yu.; Lyut'ko, E. O.; Bondareva, V. N.; Komarov, V. B.; L'vov, Yu. N.

    2012-01-15

    The radiational-thermal development of coil short circuits due to the action of partial discharges of the first kind when the windings of transformers, autotransformers and shunting reactors become contaminated with metal-containing colloidal particles, formed in the transformer oil as a result of the interaction of the oil with the constructional materials (the copper of the windings, the iron of the tank, the core etc.) is considered. Acriterion of dangerous contamination of the coil insulation of the windings by metal-containing colloidal particles is proposed, namely, 3% of the mass content of copper and iron in it, which, if exceeded, may serve as a basis for recognizing the state of transformers, autotransformers and shunting reactors at a voltage of 110 kV and above the limit. It is shown that filters for continuously cleaning the oil play a considerable role in prolonging the life of transformer equipment.

  20. Engineered metal based nanomaterials in aqueous environments: Interactions, transformations and implications

    NASA Astrophysics Data System (ADS)

    Mudunkotuwa, Imali Ama

    Nanoscience and nanotechnology offer potential routes towards addressing critical issues such as clean and sustainable energy, environmental protection and human health. Specifically, metal and metal oxide nanomaterials are found in a wide range of applications and therefore hold a greater potential of possible release into the environment or for the human to be exposed. Understanding the aqueous phase behavior of metal and metal oxide nanomaterials is a key factor in the safe design of these materials because their interactions with living systems are always mediated through the aqueous phase. Broadly the transformations in the aqueous phase can be classified as dissolution, aggregation and adsorption which are dependent and linked processes to one another. The complexity of these processes at the liquid-solid interface has therefore been one of the grand challenges that has persisted since the beginning of nanotechnology. Although classical models provide guidance for understanding dissolution and aggregation of nanoparticles in water, there are many uncertainties associated with the recent findings. This is often due to a lack of fundamental knowledge of the surface structure and surface energetics for very small particles. Therefore currently the environmental health and safety studies related to nanomaterials are more focused on understanding the surface chemistry that governs the overall processes in the liquid-solid interfacial region at the molecular level. The metal based nanomaterials focused on in this dissertation include TiO2, ZnO, Cu and CuO. These are among the most heavily used in a number of applications ranging from uses in the construction industry to cosmetic formulation. Therefore they are produced in large scale and have been detected in the environment. There is debate within the scientific community related to their safety as a result of the lack of understanding on the surface interactions that arise from the detailed nature of the surfaces

  1. Dietary toxicity of field-contaminated invertebrates to marine fish: effects of metal doses and subcellular metal distribution.

    PubMed

    Dang, Fei; Rainbow, Philip S; Wang, Wen-Xiong

    2012-09-15

    There is growing awareness of the toxicological effects of metal-contaminated invertebrate diets on the health of fish populations in metal-contaminated habitats, yet the mechanisms underlying metal bioaccumulation and toxicity are complex. In the present study, marine fish Terapon jurbua terepon were fed a commercial diet supplemented with specimens of the polychaete Nereis diversicolor or the clam Scrobicularia plana, collected from four metal-impacted estuaries (Tavy, Restronguet Creek, West Looe, Gannel) in southwest England, as environmentally realistic metal sources. A comparative toxicological evaluation of both invertebrates showed that fish fed S. plana for 21 d exhibited evident mortality compared to those fed N. diversicolor. Furthermore, a spatial effect on mortality was observed. Differences in metal doses rather than subcellular metal distributions between N. diversicolor and S. plana appeared to be the cause of such different mortalities. Partial least squares regression was used to evaluate the statistical relationship between multiple-metal doses and fish mortality, revealing that Pb, Fe, Cd and Zn in field-collected invertebrates co-varied most strongly with the observed mortality. This study provides a step toward exploring the underlying mechanism of dietary toxicity and identifying the potential causality in complex metal mixture exposures in the field.

  2. Phase-transfer based size refining of metal nanoparticles from arbitrary particle size distributions.

    PubMed

    Liu, Hui; Qu, Jianglan; Ye, Feng; Wang, Caixia; Yang, Jun

    2013-02-01

    The size-dependent phase-transfer property of metal nanoparticles is used to develop a simple experimental procedure that can effectively refine the particle size from colloidal solutions prepared by wet-chemistry. The protocol calls for firstly the mixing of the metal hydrosol with an ethanol solution of dodecylamine, and then the extraction of the dodecylamine-stabilized metal nanoparticles into toluene. This method offers an effective approach to prepare metal nanoparticles with narrow size distribution from an arbitrary particle size distribution.

  3. Radon transform based automatic metal artefacts generation for 3D threat image projection

    NASA Astrophysics Data System (ADS)

    Megherbi, Najla; Breckon, Toby P.; Flitton, Greg T.; Mouton, Andre

    2013-10-01

    Threat Image Projection (TIP) plays an important role in aviation security. In order to evaluate human security screeners in determining threats, TIP systems project images of realistic threat items into the images of the passenger baggage being scanned. In this proof of concept paper, we propose a 3D TIP method which can be integrated within new 3D Computed Tomography (CT) screening systems. In order to make the threat items appear as if they were genuinely located in the scanned bag, appropriate CT metal artefacts are generated in the resulting TIP images according to the scan orientation, the passenger bag content and the material of the inserted threat items. This process is performed in the projection domain using a novel methodology based on the Radon Transform. The obtained results using challenging 3D CT baggage images are very promising in terms of plausibility and realism.

  4. Phase Transformations and Metallization of Magnesium Oxide at High Pressure and Temperature

    NASA Astrophysics Data System (ADS)

    McWilliams, R. Stewart; Spaulding, Dylan K.; Eggert, Jon H.; Celliers, Peter M.; Hicks, Damien G.; Smith, Raymond F.; Collins, Gilbert W.; Jeanloz, Raymond

    2012-12-01

    Magnesium oxide (MgO) is representative of the rocky materials comprising the mantles of terrestrial planets, such that its properties at high temperatures and pressures reflect the nature of planetary interiors. Shock-compression experiments on MgO to pressures of 1.4 terapascals (TPa) reveal a sequence of two phase transformations: from B1 (sodium chloride) to B2 (cesium chloride) crystal structures above 0.36 TPa, and from electrically insulating solid to metallic liquid above 0.60 TPa. The transitions exhibit large latent heats that are likely to affect the structure and evolution of super-Earths. Together with data on other oxide liquids, we conclude that magmas deep inside terrestrial planets can be electrically conductive, enabling magnetic field-producing dynamo action within oxide-rich regions and blurring the distinction between planetary mantles and cores.

  5. Plastic deformation of metallic glasses: Size of shear transformation zones from molecular dynamics simulations

    NASA Astrophysics Data System (ADS)

    Zink, Mareike; Samwer, K.; Johnson, W. L.; Mayr, S. G.

    2006-05-01

    Plastic deformation in metallic glasses well below their glass transition temperatures Tg occurs spatially heterogeneously within highly localized regions, termed shear transformation zones (STZs). Yet, their size and the number of atoms involved in a local shear event, remains greatly unclear. With the help of classical molecular dynamics (MD) computer simulations on plastic deformation of the model glass CuTi during pure shearing, we address this issue by evaluating correlations in atomic-scale plastic displacements, viz. the displacement correlation function. From the correlation length, a universal diameter of about 15Å , or, equivalently, approximately 120 atoms is derived for a variety of conditions, such as variable strains, strain rates, temperatures, and boundary conditions. Our findings are consistent with a recent model proposed by Johnson and Samwer [Phys. Rev. Lett. 95, 195501 (2005)].

  6. Nickel and cadmium-induced SLBP depletion: A potential pathway to metal mediated cellular transformation

    PubMed Central

    Jordan, Ashley; Zhang, Xiaoru; Li, Jinquan; Laulicht-Glick, Freda; Sun, Hong

    2017-01-01

    Both nickel and cadmium compounds have been established as group I carcinogens for several decades. Despite over-whelming evidence of these compounds’ carcinogenicity in humans, the specific underlying molecular mechanisms that govern metal induced cellular transformation remain unclear. In this study, we found that there were slightly different effects on decreased SLBP mRNA and protein as well as increased polyA H3.1 in our nickel exposed cells. This suggested that nickel and arsenic have similar effects on canonical histone mRNA transcription and translation. We also saw that the depletion of SLBP protein was reversed by inhibiting the proteosome. Finally, we showed that inhibiting the SLBP mRNA and protein levels were rescued by epigenetic modifiers suggesting that nickel’s effects on SLBP may be mediated via epigenetic mechanisms. Taken together these results suggest a similar mechanism by which both arsenic and nickel may exert their carcinogenic effects. PMID:28306745

  7. Reversible transformations of silver oxide and metallic silver nanoparticles inside SiO{sub 2} films

    SciTech Connect

    Pal, Sudipto; De, Goutam

    2009-02-04

    Reversible transformation of silver oxide and metallic nanoparticles inside a relatively porous silica film has been established. Annealing of Ag-doped films in oxidizing (air) atmosphere at 450 deg. C yielded colorless films containing AgO{sub x}. These films were turned yellow when heated in H{sub 2}-N{sub 2} (reducing atmosphere) due to the formation of Ag nanoparticles. This yellow coloration (due to nano Ag{sup 0}) and bleaching (conversion of Ag{sup 0} {yields} Ag{sup +}) are reversible. Optical and photoluminescence spectra are well consistent with this coloration and bleaching. The soaking test of the air-annealed film in Na{sub 2}S{sub 2}O{sub 3} solution supports the presence of Ag{sup +}. Grazing incidence X-ray diffraction and transmission electron microscopy studies reveal the formation of Ag-oxides and Ag nanoparticles in the oxidized and reduced films, respectively.

  8. Effects of natural factors on the spatial distribution of heavy metals in soils surrounding mining regions.

    PubMed

    Ding, Qian; Cheng, Gong; Wang, Yong; Zhuang, Dafang

    2017-02-01

    Various studies have shown that soils surrounding mining areas are seriously polluted with heavy metals. Determining the effects of natural factors on spatial distribution of heavy metals is important for determining the distribution characteristics of heavy metals in soils. In this study, an 8km buffer zone surrounding a typical non-ferrous metal mine in Suxian District of Hunan Province, China, was selected as the study area, and statistical, spatial autocorrelation and spatial interpolation analyses were used to obtain descriptive statistics and spatial autocorrelation characteristics of As, Pb, Cu, and Zn in soil. Additionally, the distributions of soil heavy metals under the influences of natural factors, including terrain (elevation and slope), wind direction and distance from a river, were determined. Layout of sampling sites, spatial changes of heavy metal contents at high elevations and concentration differences between upwind and downwind directions were then evaluated. The following results were obtained: (1) At low elevations, heavy metal concentrations decreased slightly, then increased considerably with increasing elevation. At high elevations, heavy metal concentrations first decreased, then increased, then decreased with increasing elevation. As the slope increased, heavy metal contents increased then decreased. (2) Heavy metal contents changed consistently in the upwind and downwind directions. Heavy metal contents were highest in 1km buffer zone and decreased with increasing distance from the mining area. The largest decrease in heavy metal concentrations was in 2km buffer zone. Perennial wind promotes the transport of heavy metals in downwind direction. (3) The spatial extent of the influence of the river on Pb, Zn and Cu in the soil was 800m. (4) The influence of the terrain on the heavy metal concentrations was greater than that of the wind. These results provide a scientific basis for preventing and mitigating heavy metal soil pollution in

  9. A theoretical study of the omega-phase transformation in metals

    NASA Astrophysics Data System (ADS)

    Sanati, Mahdi

    I have studied the formation of o-phase from electronic and mesoscopic (domain wall) points of view. To study the formation of domain walls, I have extended the Landau model of Cook for the o-phase transition by including a spatial gradient (Ginzburg) term of the scalar order parameter. In general, the Landau free energy is an asymmetric double-well potential. From the variational derivative of the total free energy I obtained a static equilibrium condition. By solving this equation for different physical parameters and boundary conditions, I obtained different quasi-one-dimensional soliton-like solutions. These solutions correspond to three different types of domain walls between the o-phase and the beta-matrix. These results are used to model the formation of the o-phase in bcc Ti. Canonical band model and first principles calculations confirmed the instability of the bcc-phase of group III and IV transition metals with respect to the o-phase transformation. I showed that the d-electron density is the controlling parameter for this type of the transformation. Also the possibility of formation of the o-phase for rare earth metals is discussed. First-principles full-potential linear muffin-tin orbital method (FPLMTO) calculations are performed for o-type displacement of the atoms to study the formation of the o-phase in TiAl and Ti 3Al2Nb alloys. The results of my calculations showed an instability in ordered B2 TiAl structure with respect to the o-phase when one third of the Al atoms are replaced by Nb atoms. These phenomena are explained, first by symmetry arguments; then a pair potential model is used to illustrate this instability based on interactions between different pair of atoms derived from the electronic structure. In addition, importance of the atomic arrangements on the structural stability of the Ti3Al2 Nb system is discussed.

  10. Speciation and distribution characteristics of heavy metals and pollution assessments in the sediments of Nashina Lake, Heilongjiang, China.

    PubMed

    Li, Miao; Zang, Shuying; Xiao, Haifeng; Wu, Changshan

    2014-05-01

    Sediment core samples from Nashina Lake, Heilongjiang, China were collected using a gravity sampler. The cores were sliced horizontally at 1 cm each to determine the particle size, total concentrations and speciation of Cd, Cr, Cu, Mn, Ni, Pb, and Zn. Total concentrations of heavy metals were extracted using an acid mixture (containing hydro fluoric acid, nitric acid, and sulphuric acid) and analyzed using an inductively coupled plasma spectrometry. A sequential extraction procedure was employed to separate chemical species. Analysis of results indicate that the concentrations of heavy metals in the sediments of Nashina Lake in descending order are Mn, Cr, Zn, Pb, Ni, Cu, and Cd. The ratios of the average concentrations of four heavy metals (e.g.Cr, Cu, Ni, Zn) to their background values were >1; and those of Mn, Cd, and Pb were >1. Moreover, some toxic metals were mainly distributed in bioavailable fractions. For instance, both Cd and Mn were typically found in Acid-extractable species or Fe-Mn oxide species, and thus can be easily remobilized and enter the food chain. Finally, the analysis of geo-accumulation index showed that anthropogenic pollution levels of Cr, Cu, Mn, Ni, Zn were low, but those of Pb and Cd were at the moderate level. As both Pb and Cd are toxic metals, it is highly necessary to prohibit their transformation and accumulation in the sediments.

  11. Distribution of heavy metals in a woodland food web

    SciTech Connect

    Scharenberg, W.; Ebeling, E.

    1996-03-01

    Often investigations deal with the residue situation in contaminated areas and their effects on ecosystems, however, information are rare concerning relatively uncontaminated areas - so called {open_quotes}reference areas{close_quotes}. In such areas we can assume an insignificant influence of pollutants and we can measure the metal flux under relatively natural conditions. Since 1988 we have investigated the nutrient and energy flow as well as the metal flux in an area which is hardly influenced by anthropogenic activities besides some agro-chemical compounds. For example, the deposition and contamination of some plants is relatively low in comparison to other places in North Germany. Also the average of geological background concentrations of soil from Schleswig-Holstein are higher than soil concentrations from Bornhoeved. With this investigation we demonstrate the flux of metals through selected biotic compartments of a relatively uncontaminated woodland. Good indicators accumulating the non essential metals Cd and Pb are beetles and isopods. In contrast ground spiders, although predators, show only low metal concentrations. The essential metals Cu and Zn were relatively homogeneous in concentration in the animals. Zn showed the highest values and beetles seem to accumulate it.

  12. Monte Carlo simulations of product distributions and contained metal estimates

    USGS Publications Warehouse

    Gettings, Mark E.

    2013-01-01

    Estimation of product distributions of two factors was simulated by conventional Monte Carlo techniques using factor distributions that were independent (uncorrelated). Several simulations using uniform distributions of factors show that the product distribution has a central peak approximately centered at the product of the medians of the factor distributions. Factor distributions that are peaked, such as Gaussian (normal) produce an even more peaked product distribution. Piecewise analytic solutions can be obtained for independent factor distributions and yield insight into the properties of the product distribution. As an example, porphyry copper grades and tonnages are now available in at least one public database and their distributions were analyzed. Although both grade and tonnage can be approximated with lognormal distributions, they are not exactly fit by them. The grade shows some nonlinear correlation with tonnage for the published database. Sampling by deposit from available databases of grade, tonnage, and geological details of each deposit specifies both grade and tonnage for that deposit. Any correlation between grade and tonnage is then preserved and the observed distribution of grades and tonnages can be used with no assumption of distribution form.

  13. Effect of Lightning Protective Devices Attached to Pole Transformers on Reduction of Overvoltage on Distribution Lines

    NASA Astrophysics Data System (ADS)

    Asaoka, Yoshinobu; Asakawa, Akira; Yokoyama, Shigeru; Nakada, Kazuo; Sugimoto, Hitoshi

    : Class-10A solid-core insulators (BIL 90kV) have been used instead of class-6A pin insulators (BIL 60kV) in order to improve the insulation level of distribution lines. However, lightning protective devices attached to pole transformers may have the effect of reducing the overvoltages on phase conductors. We have investigated the lightning protection effect of devices attached to pole transformers by experiment and analysis using the EMTP (Electro-Magnetic Transients Program). The sparkover rate changes from 2.0˜3.3% to 5.5˜9.9% and increases 2.4˜2.8 times when the line insulator of the phase conductors is changed from class-10A to class-6A. It is thought that the insulation level of the line insulator can be reduced depending upon the local particularities, such as number of installed transformers, frequency of direct lightning stroke to the distribution line, and so on although the overall fault rate may increase to some extent.

  14. Quantifying Multistate Cytoplasmic Molecular Diffusion in Bacterial Cells via Inverse Transform of Confined Displacement Distribution

    PubMed Central

    2016-01-01

    Single-molecule tracking (SMT) of fluorescently tagged cytoplasmic proteins can provide valuable information on the underlying biological processes in living cells via subsequent analysis of the displacement distributions; however, the confinement effect originated from the small size of a bacterial cell skews the protein’s displacement distribution and complicates the quantification of the intrinsic diffusive behaviors. Using the inverse transformation method, we convert the skewed displacement distribution (for both 2D and 3D imaging conditions) back to that in free space for systems containing one or multiple (non)interconverting Brownian diffusion states, from which we can reliably extract the number of diffusion states as well as their intrinsic diffusion coefficients and respective fractional populations. We further demonstrate a successful application to experimental SMT data of a transcription factor in living E. coli cells. This work allows a direct quantitative connection between cytoplasmic SMT data with diffusion theory for analyzing molecular diffusive behavior in live bacteria. PMID:26491971

  15. High Pressure Phase-Transformation Induced Texture Evolution and Strengthening in Zirconium Metal: Experiment and Modeling

    PubMed Central

    Yu, Xiaohui; Zhang, Ruifeng; Weldon, David; Vogel, Sven C.; Zhang, Jianzhong; Brown, Donald W.; Wang, Yanbin; Reiche, Helmut M.; Wang, Shanmin; Du, Shiyu; Jin, Changqing; Zhao, Yusheng

    2015-01-01

    We studied the phase-transition induced texture changes and strengthening mechanism for zirconium metal under quasi-hydrostatic compression and uni-axial deformation under confined high pressure using the deformation-DIA (D-DIA) apparatus. It is shown that the experimentally obtained texture for ω-phase Zr can be qualitatively described by combining a subset of orientation variants previously proposed in two different models. The determined flow stress for the high-pressure ω-phase is 0.5–1.2 GPa, more than three times higher than that of the α-phase. Using first-principles calculations, we investigated the mechanical and electronic properties of the two Zr polymorphs. We find that the observed strengthening can be attributed to the relatively strong directional bonding in the ω phase, which significantly increases its shear plastic resistance over the α-phase Zr. The present findings provide an alternate route for Zr metal strengthening by high-pressure phase transformation. PMID:26218405

  16. High pressure phase-transformation induced texture evolution and strengthening in zirconium metal: Experiment and modeling

    SciTech Connect

    Yu, Xiaohui; Zhang, Ruifeng; Weldon, David; Vogel, Sven C.; Zhang, Jianzhong; Brown, Donald W.; Wang, Yanbin; Reiche, Helmut M.; Wang, Shanmin; Du, Shiyu; Jin, Changqing; Zhao, Yusheng

    2015-07-28

    We studied the phase-transition induced texture changes and strengthening mechanism for zirconium metal under quasi-hydrostatic compression and uni-axial deformation under confined high pressure using the deformation-DIA (D-DIA) apparatus. It is shown that the experimentally obtained texture for ω-phase Zr can be qualitatively described by combining a subset of orientation variants previously proposed in two different models. The determined flow stress for the high-pressure ω-phase is 0.5–1.2 GPa, more than three times higher than that of the α-phase. Using first-principles calculations, we investigated the mechanical and electronic properties of the two Zr polymorphs. We find that the observed strengthening can be attributed to the relatively strong directional bonding in the ω phase, which significantly increases its shear plastic resistance over the α-phase Zr. The present findings provide an alternate route for Zr metal strengthening by high-pressure phase transformation.

  17. High pressure phase-transformation induced texture evolution and strengthening in zirconium metal: Experiment and modeling

    DOE PAGES

    Yu, Xiaohui; Zhang, Ruifeng; Weldon, David; ...

    2015-07-28

    We studied the phase-transition induced texture changes and strengthening mechanism for zirconium metal under quasi-hydrostatic compression and uni-axial deformation under confined high pressure using the deformation-DIA (D-DIA) apparatus. It is shown that the experimentally obtained texture for ω-phase Zr can be qualitatively described by combining a subset of orientation variants previously proposed in two different models. The determined flow stress for the high-pressure ω-phase is 0.5–1.2 GPa, more than three times higher than that of the α-phase. Using first-principles calculations, we investigated the mechanical and electronic properties of the two Zr polymorphs. We find that the observed strengthening can bemore » attributed to the relatively strong directional bonding in the ω phase, which significantly increases its shear plastic resistance over the α-phase Zr. The present findings provide an alternate route for Zr metal strengthening by high-pressure phase transformation.« less

  18. Probing the location and distribution of paramagnetic centers in alkali metal-loaded zeolites through (7)Li MAS NMR.

    PubMed

    Terskikh, Victor V; Ratcliffe, Christopher I; Ripmeester, John A; Reinhold, Catherine J; Anderson, Paul A; Edwards, Peter P

    2004-09-15

    The nature and surroundings of lithium cations in lithium-exchanged X and A zeolites following loading with the alkali metals Na, K, Rb, and Cs have been studied through (7)Li solid-state NMR spectroscopy. It is demonstrated that the lithium in these zeolites is stable with respect to reduction by the other alkali metals. Even though the lithium cations are not directly involved in chemical interactions with the excess electrons introduced in the doping process, the corresponding (7)Li NMR spectra are extremely sensitive to paramagnetic species that are located inside the zeolite cavities. This sensitivity makes (7)Li NMR a useful probe to study the formation, distribution, and transformation of such species.

  19. Temperature Dependence of Particle Size Distribution in Transformer Oil-Based Ferrofluid

    NASA Astrophysics Data System (ADS)

    Józefczak, Arkadiusz; Hornowski, Tomasz; Skumiel, Andrzej

    2011-04-01

    The temperature dependence of the particle size distribution (PSD) of a transformer oil-based ferrofluid was studied using an ultrasound method. The measurements of the ultrasound velocity and attenuation were carried out in the absence of an external magnetic field as a function of the volume concentration of magnetite particles at temperatures ranging from 10 °C to 80 °C. The experimental results of ultrasound measurements were analyzed within the framework of the Vinogradov-Isakovich theory which takes into account contributions to acoustical parameters due to friction and heat exchange between magnetic particles and the surrounding carrier liquid. From the best fit of the experimental results and theoretical predictions, the parameters characterizing the PSD at different temperatures were determined. In order to analyze ultrasonic data, the density and viscosity of ferrofluid samples and the transformer oil were also measured.

  20. Improvements to a Model of Pole-Mounted Distribution Transformers for Electromagnetic Transient Studies

    NASA Astrophysics Data System (ADS)

    Honda, Hideki; Noda, Taku; Asakawa, Akira; Shindo, Takatoshi; Yokoyama, Shigeru; Abiko, Kenji

    The authors have previously proposed a simulation model of pole-mounted distribution transformers for electromagnetic transient calculations and validated it by comparisons between calculated and laboratory-test results. However, we recently found that the previously-proposed model gives inaccurate results for a specific type of transformers. In this paper, we make clear that the error comes from the fact that the skin effect of the secondary windings is neglected, and an improved model taking the skin effect into account is proposed. The improved model is validated by comparing simulation and laboratory-test results of surge transfer from the primary to the secondary winding and also from the secondary to the primary winding. Furthermore, the model is used in a practical lightning-surge simulation, and the result is shown to be accurate in comparison with corresponding field-test result.

  1. Ejected Particle Size Distributions from Shocked Metal Surfaces

    DOE PAGES

    Schauer, M. M.; Buttler, W. T.; Frayer, D. K.; ...

    2017-04-12

    Here, we present size distributions for particles ejected from features machined onto the surface of shocked Sn targets. The functional form of the size distributions is assumed to be log-normal, and the characteristic parameters of the distribution are extracted from the measured angular distribution of light scattered from a laser beam incident on the ejected particles. We also found strong evidence for a bimodal distribution of particle sizes with smaller particles evolved from features machined into the target surface and larger particles being produced at the edges of these features.

  2. THE STELLAR METALLICITY DISTRIBUTION FUNCTION OF THE GALACTIC HALO FROM SDSS PHOTOMETRY

    SciTech Connect

    An, Deokkeun; Beers, Timothy C.; Johnson, Jennifer A.; Pinsonneault, Marc H.; Lee, Young Sun; Bovy, Jo; Ivezic, Zeljko; Carollo, Daniela; Newby, Matthew

    2013-01-20

    We explore the stellar metallicity distribution function of the Galactic halo based on SDSS ugriz photometry. A set of stellar isochrones is calibrated using observations of several star clusters and validated by comparisons with medium-resolution spectroscopic values over a wide range of metal abundance. We estimate distances and metallicities for individual main-sequence stars in the multiply scanned SDSS Stripe 82, at heliocentric distances in the range 5-8 kpc and |b| > 35 Degree-Sign , and find that the in situ photometric metallicity distribution has a shape that matches that of the kinematically selected local halo stars from Ryan and Norris. We also examine independent kinematic information from proper-motion measurements for high Galactic latitude stars in our sample. We find that stars with retrograde rotation in the rest frame of the Galaxy are generally more metal poor than those exhibiting prograde rotation, which is consistent with earlier arguments by Carollo et al. that the halo system comprises at least two spatially overlapping components with differing metallicity, kinematics, and spatial distributions. The observed photometric metallicity distribution and that of Ryan and Norris can be described by a simple chemical evolution model by Hartwick (or by a single Gaussian distribution); however, the suggestive metallicity-kinematic correlation contradicts the basic assumption in this model that the Milky Way halo consists primarily of a single stellar population. When the observed metallicity distribution is deconvolved using two Gaussian components with peaks at [Fe/H] Almost-Equal-To -1.7 and -2.3, the metal-poor component accounts for {approx}20%-35% of the entire halo population in this distance range.

  3. Nanoscale patterning of metal nanoparticle distribution in glasses

    PubMed Central

    2013-01-01

    We show that electric field imprinting technique allows for patterning of metal nanoparticles in the glass matrix at the subwavelength scale. The formation of glass-metal nanocomposite strips with a width down to 150 nm is demonstrated. The results of near-field microscopy of imprinted patterns are in good agreement with the performed numerical modeling. Atomic force microscopy reveals that imprinting also results in the formation of nanoscale surface profile with the height going down with the decrease of the strip width. The experiments prove the applicability of this technique for the fabrication of nanoscale plasmonic components. PMID:23724801

  4. Direct transformation of methyl imines to α-iminonitriles under mild and transition-metal-free conditions.

    PubMed

    Chen, Feng; Huang, Xiaoqiang; Cui, Yuxin; Jiao, Ning

    2013-08-19

    A novel transformation of methyl imines into α-iminonitriles under mild and transition-metal-free conditions is described. Three C sp 3-H bonds are cleaved in a radical pathway at room temperature under air. Simple bromide salts are employed to assist this radical process (see scheme; FG=functional group, PIDA = iodobenzene diacetate, TMS = trimethylsilyl).

  5. KMOS view of the Galactic Centre - II. Metallicity distribution of late-type stars

    NASA Astrophysics Data System (ADS)

    Feldmeier-Krause, A.; Kerzendorf, W.; Neumayer, N.; Schödel, R.; Nogueras-Lara, F.; Do, T.; de Zeeuw, P. T.; Kuntschner, H.

    2017-01-01

    Knowing the metallicity distribution of stars in the Galactic Centre has important implications for the formation history of the Milky Way nuclear star cluster. However, this distribution is not well known, and is currently based on a small sample of fewer than 100 stars. We obtained near-infrared K-band spectra of more than 700 late-type stars in the central 4 pc2 of the Milky Way nuclear star cluster with the integral-field spectrograph KMOS (VLT). We analyse the medium-resolution spectra using a full-spectral fitting method employing the Göttingen spectral library of synthetic PHOENIX spectra. The derived stellar metallicities range from metal-rich [M/H] > +0.3 dex to metal-poor [M/H] <-1.0 dex, with a fraction of 5.2^{+6.0}_{-3.1} per cent metal-poor ([M/H] ≤ -0.5 dex) stars. The metal-poor stars are distributed over the entire observed field. The origin of metal-poor stars remains unclear. They could originate from infalling globular clusters. For the metal-rich stellar population ([M/H] > 0 dex), a globular cluster origin can be ruled out. As there is only a very low fraction of metal-poor stars in the central 4 pc2 of the Galactic Centre, we believe that our data can discard a scenario in which the Milky Way nuclear star cluster is purely formed from infalling globular clusters.

  6. Distribution and contamination of heavy metals in surface sediments of the South Yellow Sea.

    PubMed

    Yuan, Huamao; Song, Jinming; Li, Xuegang; Li, Ning; Duan, Liqin

    2012-10-01

    The distributions, annual sedimentation and atmospheric deposition flux of heavy metals have been studied in sediments of the South Yellow Sea (SYS), in order to evaluate their levels and pollution status. The higher concentrations of heavy metals were generally found in the central part of the SYS, which may be associated with the organic matters due to their high affinity to the metals. According to the calculated enrichment factor (EF) of the studied metals, Cd in the sediments posed a high risk to local environments, while Mn, Hg, Pb and Zn were at moderate risk levels. Sedimentation fluxes study in the SYS showed that most heavy metals were deposited in the Chinese offshore. Annual dry deposition flux of these metals indicated that the particulate heavy metals deposition via atmosphere also play an important role in biogeochemical cycles in the SYS.

  7. Study of metal distribution in pine and spruce needles

    SciTech Connect

    Hovorka, J.; Marshall, G.B.; Bauer, P.

    1995-12-31

    This study was performed to assess the conditions for foliar uptake of air-borne metallic pollutants on pine and spruce needles. Needles of coniferous trees (Picea abies, Pinus sylvestris, Pinus strobus) were sampled at three locations in the Protected Landscape Area Elbe Sandstone in the Czech Republic. Solid (CR) and water-soluble (WS) fractions of aerosol adhered to the needle surface, and epicuticular waxes were separated from the needle by the two-step stripping procedure. The WS and CR fractions and the needle body after the stripping procedure were separately analyzed for 24 metals. The quantity of each fraction and its elemental composition is discussed regarding the tree species, needle age and locality. Highest aerosol quantities as well as concentration of metals were found in pine needles (Pinus strobus) from the locality most exposed to the local pollution sources. Epicuticular waxes were analyzed for As, Cd and Pb. The concentrations range from 0.1 to 1.2 {micro}g/g for As and Pb, and from 0.2 to 0.6 {micro}g/g for Cd. The highest metal concentrations were found in waxes of pines (Pinus sylvestris). Values of As and Pb concentration differences between WS fraction and the wax, between the wax and the needle body decrease with the needle age while Cd concentration differences do not depend on the needle age.

  8. Trace metal distributions in the Hudson River estuary

    NASA Astrophysics Data System (ADS)

    Klinkhammer, G. P.; Bender, M. L.

    1981-06-01

    Concentations of reactive PO 4, particulate Al and dissolved and particulate Cd, Fe, Zn, Ni, Cu and Mn were measured in the Hudson River estuary. Soluble trace metal concentrations ranged from 1 to 7 parts 10 -9 Cu; 1 to 60 parts 10 -9 Mn; 0·8 to 11 parts 10 -9 Ni; 3 to 33 parts 10 -9 Zn; 0·1 to 0·5 parts 10 -9 Cd and 5 to 96 parts 10 -9 Fe. The particulate levels were 0·2 to 6 parts 10 -9 Cu; 0·2 to 40 parts 10 -9 Mn; 0·1 to 8 parts 10 -9 Ni; 0·04 to 14 parts 10 -9 Zn; 0·005 to 0·3 parts 10 -9 Cd and 7 to 2200 parts 10 -9 Fe. With the exception of iron, the discharge of these metals with Manhattan/New Jersey sewage was comparable to the riverine flux. Anthropogenic Zn, Ni and Mn inputs were reflected in dissolved concentration maxima in New York Harbor. Mass-balance calculations demonstrate that the anthropogenic fraction of these metals left the Harbor in the dissolved form. Anthropogenic Cd, Fe and Cu were associated with solids and these metals were deposited in Harbor sediments.

  9. Transformation of correlation coefficients between normal and lognormal distribution and implications for nuclear applications

    NASA Astrophysics Data System (ADS)

    Žerovnik, Gašper; Trkov, Andrej; Smith, Donald L.; Capote, Roberto

    2013-11-01

    Inherently positive parameters with large relative uncertainties (typically ≳30%) are often considered to be governed by the lognormal distribution. This assumption has the practical benefit of avoiding the possibility of sampling negative values in stochastic applications. Furthermore, it is typically assumed that the correlation coefficients for comparable multivariate normal and lognormal distributions are equivalent. However, this ideal situation is approached only in the linear approximation which happens to be applicable just for small uncertainties. This paper derives and discusses the proper transformation of correlation coefficients between both distributions for the most general case which is applicable for arbitrary uncertainties. It is seen that for lognormal distributions with large relative uncertainties strong anti-correlations (negative correlations) are mathematically forbidden. This is due to the asymmetry that is an inherent feature of these distributions. Some implications of these results for practical nuclear applications are discussed and they are illustrated with examples in this paper. Finally, modifications to the ENDF-6 format used for representing uncertainties in evaluated nuclear data libraries are suggested, as needed to deal with this issue.

  10. The mobility and distribution of heavy metals during the formation of first cycle red beds.

    USGS Publications Warehouse

    Zielinski, R.A.; Bloch, S.; Walker, T.R.

    1983-01-01

    Analysis of the heavy metal content in a Holocene-Pliocene red bed sequence near San Felipe in N Baja California, Mexico, has yielded new information on the mobility and distribution of these metals during ageing of iron oxyhydroxides from the amorphous to the crystalline state. Whole-rock samples (27) and a series of successive leachates were analysed for V, Al, Cr, Mn, Fe, Co, Ni, Cu and Zn by ICP spectrometry and for U by a delayed neutron technique. These data are supported by a variety of other mineralogical and petrographical observations. The results indicate that the metal content of the samples is predominantly inherited from the constituent detrital minerals. Reddening of the whole-rock samples does not promote major open-system migration of the heavy metals; rather, contained metals redistribute themselves on an intergranular scale, moving from detrital mineral hosts to the secondary iron oxides. The amount of secondary iron oxides and the fraction of whole-rock metals associated with these oxides increase during red-bed development. In addition, the abundance of well- crystallized iron oxides increases during this period. Differences in the leaching efficiency for various metals are related to differences in metal site distribution and intergranular permeability. Inferred conditions for rapid vs limited removal of metals from red beds are summarized. It is suggested that developed red beds which are well flushed by suitable pore fluids may be sources of significant quantities of heavy metals. -J.E.S.

  11. Correction: Number density distribution of solvent molecules on a substrate: a transform theory for atomic force microscopy.

    PubMed

    Amano, Ken-Ichi; Liang, Yunfeng; Miyazawa, Keisuke; Kobayashi, Kazuya; Hashimoto, Kota; Fukami, Kazuhiro; Nishi, Naoya; Sakka, Tetsuo; Onishi, Hiroshi; Fukuma, Takeshi

    2016-08-07

    Correction for 'Number density distribution of solvent molecules on a substrate: a transform theory for atomic force microscopy' by Ken-ichi Amano et al., Phys. Chem. Chem. Phys., 2016, 18, 15534-15544.

  12. Heavy metals distribution in sediments of Nador lagoon (Morocco)

    NASA Astrophysics Data System (ADS)

    Bloundi, K.; Duplay, J.

    2003-04-01

    The Nador lagoon is a paralic system, located North-East of Morocco. At the present time this ecosystem undergoes an anthropic stress induced by urban, industrial and agricultural releases, and also by fishery activity which enriches this ecosystem in organic and inorganic wastes. A geochemical study has been undertaken, first to define the areas contaminated by heavy metals (Zn, Cu, Co, Cr and V), and second to caracterize the different mineral phases, which trap these elements. Sediment samples were collected on twenty-eight stations scattered all over the lagoon, and each core (30 cm) was subdivided in two horizons (surface and depth). Mineralogical analyses as well as major and trace elements analyses were performed on surface and deep sediments. The results on major element analyses (Si, Al, Ca, Mg, Na, P) show an enrichment in halite and phosphates in the surface sediments. This highlights on one hand, low water exchange rates between the lagoon and the Mediterranean sea, and on the other hand, an increase in organic releases related to the urban, agricultural and fishery activities. The highest concentrations in inorganic micro-pollutant were recorded N-E of the lagoon and close to Nador city. With reference to the geochemical background, it can be concluded that there is a slight contamination in heavy metals. Moreover, enrichment factor calculations (EF) for heavy metals point out an increase in metal elements as following: Zn>Co>Cr>V>Cu. Sequential extractions were performed to determine the behaviour of these micro-pollutants. Thus, it was shown that carbonates, oxides and phosphates are the preferential mineral phases for trapping these heavy metals.

  13. Defect distribution and Schottky barrier at metal/Ge interfaces: Role of metal-induced gap states

    NASA Astrophysics Data System (ADS)

    Sasaki, Shogo; Nakayama, Takashi

    2016-11-01

    The defect distribution and Schottky barrier at metal/Ge interfaces were studied using first-principles calculation. It was shown that the defect density markedly increases around the interface owing to the stabilization caused by the hybridization of defect electronic states with metal-induced gap states (MIGS) and by the associated small elastic energy loss around the interface. By comparing the formation energies of various defects at a variety of metal/substrate interfaces, we showed that MIGS not only control the Schottky barrier but also promote a defect-density increase at most metal/semiconductor interfaces. Moreover, we showed that interface oxide layers block MIGS penetration into the Ge substrate and promote the observed breakdown of Fermi-level pinning.

  14. Possible stibnite transformation at the friction surface of the semi-metallic friction composites designed for car brake linings

    NASA Astrophysics Data System (ADS)

    Matějka, V.; Lu, Y.; Matějková, P.; Smetana, B.; Kukutschová, J.; Vaculík, M.; Tomášek, V.; Zlá, S.; Fan, Y.

    2011-12-01

    After a friction process several changes in phase composition of friction composites are often registered. High temperature, accompanied by high pressure induced during braking can cause initiation of chemical reactions which do not run at room or elevated temperatures under the atmospheric pressure. Most of the studies in the field of tribochemistry at friction surfaces of automotive semi-metallic brake linings deal with phenolic resin degradation and corrosion of metallic components. The paper addresses the formation of elemental antimony as well as the alloying process of iron with antimony observed on the surface of laboratory prepared semi-metallic friction composites containing stibnite. The role of alumina abrasives in the process of stibnite transformation is also discussed and mechanism of stibnite transformation was outlined.

  15. Coordinated distribution network control of tap changer transformers, capacitors and PV inverters

    DOE PAGES

    Ceylan, Oğuzhan; Liu, Guodong; Tomsovic, Kevin

    2017-06-08

    A power distribution system operates most efficiently with voltage deviations along a feeder kept to a minimum and must ensure all voltages remain within specified limits. Recently with the increased integration of photovoltaics, the variable power output has led to increased voltage fluctuations and violation of operating limits. This study proposes an optimization model based on a recently developed heuristic search method, grey wolf optimization, to coordinate the various distribution controllers. Several different case studies on IEEE 33 and 69 bus test systems modified by including tap changing transformers, capacitors and photovoltaic solar panels are performed. Simulation results are comparedmore » to two other heuristic-based optimization methods: harmony search and differential evolution. Finally, the simulation results show the effectiveness of the method and indicate the usage of reactive power outputs of PVs facilitates better voltage magnitude profile.« less

  16. A coordinate transformation method for calculating the 3D light intensity distribution in ICF hohlraum

    NASA Astrophysics Data System (ADS)

    Lin, Zhili; Li, Xiaoyan; Zhao, Kuixia; Chen, Xudong; Chen, Mingyu; Pu, Jixiong

    2016-06-01

    For an inertial confinement fusion (ICF) system, the light intensity distribution in the hohlraum is key to the initial plasma excitation and later laser-plasma interaction process. Based on the concept of coordinate transformation of spatial points and vector, we present a robust method with a detailed procedure that makes the calculation of the three dimensional (3D) light intensity distribution in hohlraum easily. The method is intuitive but powerful enough to solve the complex cases of random number of laser beams with arbitrary polarization states and incidence angles. Its application is exemplified in the Shenguang III Facility (SG-III) that verifies its effectiveness and it is useful for guiding the design of hohlraum structure parameter.

  17. Analysis of Distribution of Time Scores in Iterative Learning Type Courseware Using Fourier Transform

    NASA Astrophysics Data System (ADS)

    Watanabe, Hiroyuki

    In this research, an iterative learning type courseware was made, the distribution of time scores in the courseware is gotten by the learning management system. It is a proposed method by which the distribution of time scores is changed to frequency and to power spectrum using Fourier Transform. The learning process continues until students get the passing scores and are classified by using these values, which are related to average time and the average of scores‧ square. Furthermore, the cross-correlation coefficients between the standard student and students are calculated, and delay times are analyzed. Finally, the transfer functions of some students are calculated, and the characteristics of the learning processes are analyzed.

  18. Impacts of sewage irrigation on heavy metal distribution and contamination in Beijing, China.

    PubMed

    Liu, Wen-hua; Zhao, Jing-zhu; Ouyang, Zhi-yun; Söderlund, Leif; Liu, Guo-hua

    2005-08-01

    A potential hazard to Beijing was revealed due to the accumulation trend of heavy metals in agricultural soils with sewage irrigation, which results in metal contamination and human exposure risk. Samples including soils and plants were collected to assess the impacts of sewage irrigation on the irrigated farming area of Beijing. Concentrations of the five elements Cd, Cr, Cu, Zn, and Pb were determined in samples to calculate the accumulation factor and to establish a basis for environmental protection and the suitability of sewage irrigation for particular land use in the urban-rural interaction area of Beijing. Using reference values provided by the Beijing Background Research Cooperative Group in the 1970s, the pollution load index (PLI), enrichment factor (EF), and contamination factor (CF) of these metals were calculated. The pollution load indices (sewage irrigation land 3.49) of soils indicated that metal contamination occurred in these sites. The metal enrichment (EF of Cd 1.8, Cr 1.7, Cu 2.3, Zn 2.0, Pb 1.9) and the metal contamination (CF of Cd 2.6, Cr 1.5, Cu 2.0, Zn 1.7, Pb 1.6) showed that the accumulation trend of the five toxic metals increased during the sewage irrigation as compared with the lower reference values than other region in China and world average, and that pollution with Cd, Cu, Zn, and Pb was exacerbated in soils. The distributions of these metals were homogeneous in the irrigation area, but small-scale heterogeneous spatial distribution was observed. Irrigation sources were found to affect heavy metal distributions in soils. It was suggested that heavy metal transfer from soils to plants was a key pathway to human health exposure to metal contamination. However, with the expansion of urban areas in Beijing, soil inhalation and ingestion may become important pathways of human exposure to metal contamination.

  19. Oxidative transformation of iron monosulfides and pyrite in estuarine sediments: Implications for trace metals mobilisation.

    PubMed

    Choppala, Girish; Bush, Richard; Moon, Ellen; Ward, Nicholas; Wang, Zhaohui; Bolan, Nanthi; Sullivan, Leigh

    2017-01-15

    Iron monosulfides are the initial iron sulfide minerals that form under reducing conditions in organic-rich sediments. Frequently referred as monosulfidic black ooze (MBO), these sediments exists in a range of anoxic systems including estuaries, coastal wetlands and permeable reactive barriers. The objective of this study was to investigate the transformation of solid phase sulfur, iron fractions and trace metals mobilisation in organic-rich hypersulfidic sediments during dredging. Two sediments from geographically contrasting sites in the Peel-Harvey Estuary were collected and subjected to oxidation through resuspension over 14 days. During oxidation, redox potential rapidly and continuously increased, although minimal change in pH was observed in both sediments. The majority of FeS was oxidised within 48 h. Although not as dynamic as FeS, unusually high rates of FeS2 oxidation were measured in both sediments at circumneutral pH, with between 39 and 58% of FeS2 oxidised over 14 days. The rapid oxidation of FeS2 may be attributed to the presence of nano-size FeS2 crystals (≈550-860 nm) with a high surface area. Before resuspension, solid bound Fe(total) was most abundant as measured by HCl-extractable Fe(II), followed by organic bound Fe(total) and oxide bound Fe(total). There was a marked decrease in these three fractions in both sediments during resuspension, with an increase in Fe(III) fraction. No significant release of trace metals was observed during resuspension of sulfidic sediments. However, disturbance to these estuarine sediments increases Fe(III) formation and further deteriorates the environment through smothering biological surfaces, deteriorating food sources and the quality of benthic habitats. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. Advanced analysis of metal distributions in human hair

    SciTech Connect

    Kempson, Ivan M.; Skinner, William M.

    2008-06-09

    A variety of techniques (secondary electron microscopy with energy dispersive X-ray analysis, time-of-flight-secondary ion mass spectrometry, and synchrotron X-ray fluorescence) were utilized to distinguish metal contamination occurring in hair arising from endogenous uptake from an individual exposed to a polluted environment, in this case a lead smelter. Evidence was sought for elements less affected by contamination and potentially indicative of biogenic activity. The unique combination of surface sensitivity, spatial resolution, and detection limits used here has provided new insight regarding hair analysis. Metals such as Ca, Fe, and Pb appeared to have little representative value of endogenous uptake and were mainly due to contamination. Cu and Zn, however, demonstrate behaviors worthy of further investigation into relating hair concentrations to endogenous function.

  1. Distribution of heavy metals in Elcho Island, Northern Territory, Australia.

    PubMed

    Peerzada, N; Pakkiyaretnam, T; Skliros, S; Guinea, M; Ryan, P

    1992-06-01

    The concentration of four metals in waters and seven metals in oysters, clams and sediments from Elcho Island, Northern Territory, were determined during the dry season of 1987. The measured concentration of cadmium, zinc, copper and lead in unfiltered water were: cadmium, 0.02-0.27; zinc, 0.09-3.70; copper, 0.60-4.78; lead, 0.12-2.39 micrograms l-1, and iron, cadmium, zinc, manganese, copper, nickel and lead in oysters, 13.07-273.55, 0.29-10.63, 2.39-8.51, 0.25-4.84, 0.45-8.76, 0.16-0.59, 2.59-9.38 micrograms g-1 wet weight, and in clam, 94.84-419, 6.0-20.3, 1.09-6.28, 2515-6256, 0.47-3.18, 1.71-5.64, 0.45-2.17 micrograms g-1 wet weight, and in sediments, 3219.1-10871.1, 1.36-2.68, 2.7-6.55, 19.4-105.7, 0.65-1.91, 4.16-21.8 and 5.66-23.9 micrograms g-1 dry weight. Accumulation of manganese in razor clam was highest in spite of low concentration in the surrounding sediment, therefore it could be used as a bioindicator of manganese in a tropical environment. The level of cadmium and lead exceeded the National Health and Medical Research Council (NHMRC) recommended limit. In general, level of other metals were lower as compared to the concentration of these metals in Darwin Harbour.

  2. Heavy metals distribution in an Iowa suburban landscape.

    PubMed

    Langner, A N; Manu, A; Tabatabai, M A

    2011-01-01

    This study investigated the degree to which human activities through urbanization influence heavy metal concentrations in a suburban landscape in Ankeny, IA. Residential areas from different years in nine time periods of development were identified from aerial photos. Soil cores were collected from the center of the front yard of 10 randomly selected homes. Cores were subdivided into 0- to 5-, 5- to 10-, and 10- to 20-cm increments from a composite of five cores. The soils were analyzed for organic C, pH, and total Cd, Co, Cr, Cu, Ni, Pb, and Zn. Results showed that organic C increased and pH decreased with time, and that there was a general decreasing trend in heavy metal concentrations from the pre-1939 period until 1983-1990, after which there was a sharp increase in the concentrations of most of the metals. The mean Cu concentration ranged from 21 mg kg(-1) for the pre-1939 time period of development to 14.9 mg kg(-1) for the recent period of development (2003-2005). Nickel concentrations increased significantly with depth with means of 21.3 mg kg(-1) at depth 0 to 5 cm, 22.5 mg kg(-1) at depth 5 to 10 cm, and 23.0 mg kg(-1) at depth 10 to 20 cm. The concentrations of heavy metals were significantly intercorrelated, except Zn, suggesting their coexistence as mineral constituents or common contamination source. The concentrations of Cu and Pb in some locations could be due to anthropogenic inputs or higher organic matter content in soils adjacent to older homes. There appears to have been a source that caused an increase in Cd, Cr, Co, Cu, Pb, and Ni concentrations in soil adjacent to homes built between 1983 and 1990.

  3. In situ-generated metal oxide catalyst during CO oxidation reaction transformed from redox-active metal-organic framework-supported palladium nanoparticles

    PubMed Central

    2012-01-01

    The preparation of redox-active metal-organic framework (ra-MOF)-supported Pd nanoparticles (NPs) via the redox couple-driven method is reported, which can yield unprotected metallic NPs at room temperature within 10 min without the use of reducing agents. The Pd@ra-MOF has been exploited as a precursor of an active catalyst for CO oxidation. Under the CO oxidation reaction condition, Pd@ra-MOF is transformed into a PdOx-NiOy/C nanocomposite to generate catalytically active species in situ, and the resultant nanocatalyst shows sustainable activity through synergistic stabilization. PMID:22898143

  4. Spatial distribution and transport characteristics of heavy metals around an antimony mine area in central China.

    PubMed

    Li, Xin; Yang, Hong; Zhang, Chang; Zeng, Guangming; Liu, Yunguo; Xu, Weihua; Wu, Youe; Lan, Shiming

    2017-03-01

    The spatial distribution and transport characteristics of heavy metals in an antimony mine area (Xikuangshan, China) were systematically studied using a field survey and geostatistical analytical methods. In the study area, 52 soil and sediment samples were collected from bare land, grassland, woodland and river sediments covering a surface area of 20 km(2). The soil properties and heavy metal concentrations were measured by wavelength dispersive X-ray fluorescence spectrometry and inductively coupled plasma-mass spectrometry, respectively. Correlation analysis and principal component analysis suggest that Cu, Zn, Cd, As, Pb and Sb can be attributed to anthropogenic inputs, whereas Cr, Mn and Ni are of natural origin. Distribution maps of heavy metals were generated using the Kriging interpolation method to identify their distribution trends. The results show the influence of wind, river, distance and vegetation on the spatial distribution. The results also revealed that windborne transport may play a significant role in the spreading of contaminants. In addition, the environmental risk of heavy metal pollution was evaluated using their geoaccumulation indexes in the whole region. All of the results indicate that the heavy metal distributions in the soils were consistent with the local prevailing wind direction. In addition, the environmental quality could be seriously threatened by heavy metal contaminants from the smelter and tailings.

  5. Distribution of heavy metal concentrations in surface sediments in Dubai Creeks, United Arab Emirates.

    PubMed

    Howari, Fares M

    2005-01-01

    Dubai is developing rapidly and many developmental activities are concentrated around its Creek. The present study reports the lateral distribution of heavy metals and compares it with local historical record of heavy metal concentrations. For this purpose surface sediment samples were collected and analyzed for metal contents, total organic carbon content (TOC), mineralogy and grain size. The percentages of the different grain size fraction of the collected sediments were as follow 65% for sand size, 15% for silt size fraction, and the rest accounted for clay size fraction. The microscopic analyses indicate that the sediment composed mainly from carbonate and quartz with traces of rock fragments. Such mineral composition is not believed to be a potential source of heavy metal. The study found that the average recorded heavy metal concentrations in the collected sediment samples were 87, 96, 127, 38.5, and 279 ppm for Cr, Cu, Ni, Pb, and Zn, respectively. Those values were slightly higher than metal concentrations recoded in 2001 with 1.22 (Cr), 2.5 (Cu), 2.87 (Ni), 0.69 (Pb), and 2.1 (Zn) folds. However, in 2001 and 2003 the measured metal contents, along the creek, were lower than those of the average earth crust. Along the Creek most metals recorded the highest concentrations in the upper reach of the Creek. The distribution of the measured heavy metals was not affected significantly with the TOC values. The present study also documented obvious related point sources of pollution.

  6. Ecological risk assessment on heavy metals in soils: Use of soil diffuse reflectance mid-infrared Fourier-transform spectroscopy

    PubMed Central

    Wang, Cheng; Li, Wei; Guo, Mingxing; Ji, Junfeng

    2017-01-01

    The bioavailability of heavy metals in soil is controlled by their concentrations and soil properties. Diffuse reflectance mid-infrared Fourier-transform spectroscopy (DRIFTS) is capable of detecting specific organic and inorganic bonds in metal complexes and minerals and therefore, has been employed to predict soil composition and heavy metal contents. The present study explored the potential of DRIFTS for estimating soil heavy metal bioavailability. Soil and corresponding wheat grain samples from the Yangtze River Delta region were analyzed by DRIFTS and chemical methods. Statistical regression analyses were conducted to correlate the soil spectral information to the concentrations of Cd, Cr, Cu, Zn, Pb, Ni, Hg and Fe in wheat grains. The principal components in the spectra influencing soil heavy metal bioavailability were identified and used in prediction model construction. The established soil DRIFTS-based prediction models were applied to estimate the heavy metal concentrations in wheat grains in the mid-Yangtze River Delta area. The predicted heavy metal concentrations of wheat grain were highly consistent with the measured levels by chemical analysis, showing a significant correlation (r2 > 0.72) with acceptable root mean square error RMSE. In conclusion, DRIFTS is a promising technique for assessing the bioavailability of soil heavy metals and related ecological risk. PMID:28198802

  7. Ecological risk assessment on heavy metals in soils: Use of soil diffuse reflectance mid-infrared Fourier-transform spectroscopy

    NASA Astrophysics Data System (ADS)

    Wang, Cheng; Li, Wei; Guo, Mingxing; Ji, Junfeng

    2017-02-01

    The bioavailability of heavy metals in soil is controlled by their concentrations and soil properties. Diffuse reflectance mid-infrared Fourier-transform spectroscopy (DRIFTS) is capable of detecting specific organic and inorganic bonds in metal complexes and minerals and therefore, has been employed to predict soil composition and heavy metal contents. The present study explored the potential of DRIFTS for estimating soil heavy metal bioavailability. Soil and corresponding wheat grain samples from the Yangtze River Delta region were analyzed by DRIFTS and chemical methods. Statistical regression analyses were conducted to correlate the soil spectral information to the concentrations of Cd, Cr, Cu, Zn, Pb, Ni, Hg and Fe in wheat grains. The principal components in the spectra influencing soil heavy metal bioavailability were identified and used in prediction model construction. The established soil DRIFTS-based prediction models were applied to estimate the heavy metal concentrations in wheat grains in the mid-Yangtze River Delta area. The predicted heavy metal concentrations of wheat grain were highly consistent with the measured levels by chemical analysis, showing a significant correlation (r2 > 0.72) with acceptable root mean square error RMSE. In conclusion, DRIFTS is a promising technique for assessing the bioavailability of soil heavy metals and related ecological risk.

  8. Advances in Stereoconvergent Catalysis from 2005 to 2015: Transition-Metal-Mediated Stereoablative Reactions, Dynamic Kinetic Resolutions, and Dynamic Kinetic Asymmetric Transformations.

    PubMed

    Bhat, Vikram; Welin, Eric R; Guo, Xuelei; Stoltz, Brian M

    2017-03-08

    Stereoconvergent catalysis is an important subset of asymmetric synthesis that encompasses stereoablative transformations, dynamic kinetic resolutions, and dynamic kinetic asymmetric transformations. Initially, only enzymes were known to catalyze dynamic kinetic processes, but recently various synthetic catalysts have been developed. This Review summarizes major advances in nonenzymatic, transition-metal-promoted dynamic asymmetric transformations reported between 2005 and 2015.

  9. Understanding structure, metal distribution, and water adsorption in mixed-metal MOF-74

    SciTech Connect

    Howe, Joshua D.; Morelock, Cody R.; Jiao, Yang; Chapman, Karena W.; Walton, Krista S.; Sholl, David S.

    2016-11-30

    We present a joint computational and experimental study of Mg–Ni-MOF-74 and Mg–Cd-MOF-74 to gain insight into the mixing of metals and understand how metal mixing affects the structure of the undercoordinated open-metal sites. Our calculations predict that metal mixing is energetically preferred in these materials. Recent experimental work has demonstrated that Mg–Ni-MOF-74 shows a much greater surface area retention in the presence of water than Mg-MOF-74. To probe this effect, we study H2O adsorption in Mg–Ni-MOF-74, finding that the adsorption energetics and electronic structure do not change significantly at the metal sites when compared to Mg-MOF-74 and Ni-MOF-74, respectively. Lastly, we conclude that the increased stability of Mg–Ni-MOF-74 is a result of a M–O bond length distortion in mixed-metal MOF-74, consistent with recent work on the stability of MOF-74 under water exposure.

  10. Understanding structure, metal distribution, and water adsorption in mixed-metal MOF-74

    DOE PAGES

    Howe, Joshua D.; Morelock, Cody R.; Jiao, Yang; ...

    2016-11-30

    We present a joint computational and experimental study of Mg–Ni-MOF-74 and Mg–Cd-MOF-74 to gain insight into the mixing of metals and understand how metal mixing affects the structure of the undercoordinated open-metal sites. Our calculations predict that metal mixing is energetically preferred in these materials. Recent experimental work has demonstrated that Mg–Ni-MOF-74 shows a much greater surface area retention in the presence of water than Mg-MOF-74. To probe this effect, we study H2O adsorption in Mg–Ni-MOF-74, finding that the adsorption energetics and electronic structure do not change significantly at the metal sites when compared to Mg-MOF-74 and Ni-MOF-74, respectively. Lastly,more » we conclude that the increased stability of Mg–Ni-MOF-74 is a result of a M–O bond length distortion in mixed-metal MOF-74, consistent with recent work on the stability of MOF-74 under water exposure.« less

  11. Angular distribution of particles sputtered from metals and alloys

    SciTech Connect

    Wucher, A.; Reuter, W.

    1988-07-01

    The angular distributions of atoms sputtered from pure Cu and Be as well as Cu/sub 98/Be/sub 2/, Cu/sub 71/Zn/sub 29/, Co/sub 3/Au, and WSi/sub 2.3/ were investigated for bombardment with Ar/sup +/ ions of 250 eV and 2 keV under normal incidence. Between polar emission angles theta = 0/sup 0/ and 60/sup 0/, for the higher bombarding energy all observed angular distributions look very much alike and follow essentially a cos/sup 3/ theta law. For the low bombarding energy, however, significant differences between the angular distributions of the alloy constituents are found. The effect, which is most pronounced for CuBe, seems to scale with the atomic mass in the way that the lower mass particles are sputtered preferentially along the surface normal.

  12. Influence of metal of the applicator on the dose distribution during brachytherapy.

    PubMed

    Wu, Chin-Hui; Shiau, An-Cheng; Liao, Yi-Jen; Lin, Hsin-Yu; Liu, Yen-Wan Hsueh; Hsu, Shih-Ming

    2014-01-01

    This study explores how the metal materials of the applicator influence the dose distribution when performing brachytherapy for cervical cancer. A pinpoint ionization chamber, Monte Carlo code MCNPX, and treatment planning system are used to evaluate the dose distribution for a single Ir-192 source positioned in the tandem and ovoid. For dose distribution in water with the presence of the tandem, differences among measurement, MCNPX calculation and treatment planning system results are <5%. For dose distribution in water with the presence of the ovoid, the MCNPX result agrees with the measurement. But the doses calculated from treatment planning system are overestimated by up to a factor of 4. This is due to the shielding effect of the metal materials in the applicator not being considered in the treatment planning system. This result suggests that the treatment planning system should take into account corrections for the metal materials of the applicator in order to improve the accuracy of the radiation dose delivered.

  13. The GIRAFFE Inner Bulge Survey (GIBS). III. Metallicity distributions and kinematics of 26 Galactic bulge fields

    NASA Astrophysics Data System (ADS)

    Zoccali, M.; Vasquez, S.; Gonzalez, O. A.; Valenti, E.; Rojas-Arriagada, A.; Minniti, J.; Rejkuba, M.; Minniti, D.; McWilliam, A.; Babusiaux, C.; Hill, V.; Renzini, A.

    2017-02-01

    Context. Several recent studies have demonstrated that the Galactic bulge hosts two components with different mean metallicities, and possibly different spatial distribution and kinematics. As a consequence, both the metallicity distribution and the radial velocity of bulge stars vary across different lines of sight. Aims: We present here the metallicity distribution function of red clump stars in 26 fields spread across a wide area of the bulge, with special emphasis on fields close to Galactic plane, at latitudes b = -2° and b = -1°, that have not been explored before. Methods: This paper includes new metallicities from a sample of approximately 5000 K giant stars, observed at spectral resolution R 6500, in the Calcium II Triplet region. These represent the main dataset from the GIRAFFE Inner Bulge Survey. As part of the same survey we have previously published results for a sample of approximately 600 K giant stars, at latitude b -4°, derived from higher resolution spectra (R = 22 500). Results: The combined sample allows us to trace and characterize the metal poor and metal rich bulge populations down to the inner bulge. We present a density map for each of the two components. Contrary to expectations from previous works, we found the metal poor population to be more centrally concentrated than the metal rich one, and with a more axisymmetric spatial distribution. The metal rich population, on the other hand, is arranged in a boxy distribution, consistent with an edge-on bar. By coupling metallicities and radial velocities we show that the metal poor population has a velocity dispersion that varies rather mildly with latitude. On the contrary, the metal rich population has a low velocity dispersion far from the plane (b = -8.5°), yet has a steeper gradient with latitude, becoming higher than the metal poor one in the innermost field (b = -1°). Conclusions: This work provides new observational constraints on the actual chemodynamical properties of the

  14. Distribution and Potential Toxicity of Trace Metals in the Surface Sediments of Sundarban Mangrove Ecosystem, Bangladesh

    NASA Astrophysics Data System (ADS)

    Kumar, A.; Ramanathan, A.; Mathukumalli, B. K. P.; Datta, D. K.

    2014-12-01

    The distribution, enrichment and ecotoxocity potential of Bangladesh part of Sundarban mangrove was investigated for eight trace metals (As, Cd, Cr, Cu, Fe, Mn, Pb and Zn) using sediment quality assessment indices. The average concentration of trace metals in the sediments exceeded the crustal abundance suggesting sources other than natural in origin. Additionally, the trace metals profile may be a reflection of socio-economic development in the vicinity of Sundarban which further attributes trace metals abundance to the anthropogenic inputs. Geoaccumulation index suggests moderately polluted sediment quality w.r.t. Ni and As and background concentrations for Al, Fe, Mn, Cu, Zn, Pb, Co, As and Cd. Contamination factor analysis suggested low contamination by Zn, Cr, Co and Cd, moderate by Fe, Mn, Cu and Pb while Ni and As show considerable and high contamination, respectively. Enrichment factors for Ni, Pb and As suggests high contamination from either biota or anthropogenic inputs besides natural enrichment. As per the three sediment quality guidelines, Fe, Mn, Cu, Ni, Co and As would be more of a concern with respect to ecotoxicological risk in the Sundarban mangroves. The correlation between various physiochemical variables and trace metals suggested significant role of fine grained particles (clay) in trace metal distribution whereas owing to low organic carbon content in the region the organic complexation may not be playing significant role in trace metal distribution in the Sundarban mangroves.

  15. A Large Stellar Evolution Database for Population Synthesis Studies. II. Stellar Models and Isochrones for an α-enhanced Metal Distribution

    NASA Astrophysics Data System (ADS)

    Pietrinferni, Adriano; Cassisi, Santi; Salaris, Maurizio; Castelli, Fiorella

    2006-05-01

    We present a large, new set of stellar evolution models and isochrones for an α-enhanced metal distribution typical of Galactic halo and bulge stars; it represents a homogeneous extension of our stellar model library for a scaled-solar metal distribution already presented by Pietrinferni et al. The effect of the α-element enhancement has been properly taken into account in the nuclear network, opacity, equation of state, and for the first time in the bolometric corrections and color transformations. This allows us to avoid the inconsistent use-common to all α-enhanced model libraries currently available-of scaled-solar bolometric corrections and color transformations for α-enhanced models and isochrones. We show how bolometric corrections to magnitudes obtained for the U, B portion of stellar spectra for Teff<=6500 K are significantly affected by the metal mixture, especially at the higher metallicities. Our models cover both an extended mass range (between 0.5 and 10 Msolar, with a fine mass spacing) and a broad metallicity range, including 11 values of the metal mass fraction Z, corresponding to the range -2.6<=[Fe/H]<=0.05. The initial He mass fraction is Y=0.245 for the most metal-poor models, and it increases with Z, according to ΔY/ΔZ=1.4. Models with and without the inclusion of overshoot from the convective cores during the central H-burning phase are provided, as well as models with different mass loss efficiencies. We also provide complete sets of evolutionary models for low-mass, He-burning stellar structures cover the whole metallicity range. This database, used in combination with our scaled-solar model library, is a valuable tool for investigating both Galactic and extragalactic simple and composite stellar populations, using stellar population synthesis techniques.

  16. Effect of Drying on Heavy Metal Fraction Distribution in Rice Paddy Soil

    PubMed Central

    Qi, Yanbing; Huang, Biao; Darilek, Jeremy Landon

    2014-01-01

    An understanding of how redox conditions affect soil heavy metal fractions in rice paddies is important due to its implications for heavy metal mobility and plant uptake. Rice paddy soil samples routinely undergo oxidation prior to heavy metal analysis. Fraction distribution of Cu, Pb, Ni, and Cd from paddy soil with a wide pH range was investigated. Samples were both dried according to standard protocols and also preserved under anaerobic conditions through the sampling and analysis process and heavy metals were then sequentially extracted for the exchangeable and carbonate bound fraction (acid soluble fraction), iron and manganese oxide bound fraction (reducible fraction), organic bound fraction (oxidizable fraction), and residual fraction. Fractions were affected by redox conditions across all pH ranges. Drying decreased reducible fraction of all heavy metals. Curesidual fraction, Pboxidizable fraction, Cdresidual fraction, and Niresidual fraction increased by 25%, 33%, 35%, and >60%, respectively. Pbresidual fraction, Niacid soluble fraction, and Cdoxidizable fraction decreased 33%, 25%, and 15%, respectively. Drying paddy soil prior to heavy metal analysis overestimated Pb and underestimated Cu, Ni, and Cd. In future studies, samples should be stored after injecting N2 gas to maintain the redox potential of soil prior to heavy metal analysis, and investigate the correlation between heavy metal fraction distribution under field conditions and air-dried samples. PMID:24823670

  17. Effect of drying on heavy metal fraction distribution in rice paddy soil.

    PubMed

    Qi, Yanbing; Huang, Biao; Darilek, Jeremy Landon

    2014-01-01

    An understanding of how redox conditions affect soil heavy metal fractions in rice paddies is important due to its implications for heavy metal mobility and plant uptake. Rice paddy soil samples routinely undergo oxidation prior to heavy metal analysis. Fraction distribution of Cu, Pb, Ni, and Cd from paddy soil with a wide pH range was investigated. Samples were both dried according to standard protocols and also preserved under anaerobic conditions through the sampling and analysis process and heavy metals were then sequentially extracted for the exchangeable and carbonate bound fraction (acid soluble fraction), iron and manganese oxide bound fraction (reducible fraction), organic bound fraction (oxidizable fraction), and residual fraction. Fractions were affected by redox conditions across all pH ranges. Drying decreased reducible fraction of all heavy metals. Curesidual fraction, Pboxidizable fraction, Cdresidual fraction, and Niresidual fraction increased by 25%, 33%, 35%, and >60%, respectively. Pbresidual fraction, Niacid soluble fraction, and Cdoxidizable fraction decreased 33%, 25%, and 15%, respectively. Drying paddy soil prior to heavy metal analysis overestimated Pb and underestimated Cu, Ni, and Cd. In future studies, samples should be stored after injecting N2 gas to maintain the redox potential of soil prior to heavy metal analysis, and investigate the correlation between heavy metal fraction distribution under field conditions and air-dried samples.

  18. PM2.5-bound metal metabolic distribution and coupled lipid abnormality at different developmental windows.

    PubMed

    Ku, Tingting; Zhang, Yingying; Ji, Xiaotong; Li, Guangke; Sang, Nan

    2017-09-01

    Atmospheric fine particulate matter (PM2.5) is a serious threat to human health. As a toxicant constituent, metal leads to significant health risks in a population, but exposure to PM2.5-bound metals and their biological impacts are not fully understood. In this study, we determined the metal contents of PM2.5 samples collected from a typical coal-burning city and then investigated the metabolic distributions of six metals (Zn, Pb, Mn, As, Cu, and Cd) following PM2.5 inhalation in mice in different developmental windows. The results indicate that fine particles were mainly deposited in the lung, but PM2.5-bound metals could reach and gather in secondary off-target tissues (the lung, liver, heart and brain) with a developmental window-dependent property. Furthermore, elevations in triglycerides and cholesterol levels in sensitive developmental windows (the young and elderly stages) occurred, and significant associations between metals (Pb, Mn, As and Cd) and cholesterol in the heart, brain, liver and lung were observed. These findings suggest that PM2.5 inhalation caused selective metal metabolic distribution in tissues with a developmental window-dependent property and that the effects were associated with lipid alterations. This provides a foundation for the underlying systemic toxicity following PM2.5 exposure based on metal components. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. [Effect of reclaimed water irrigation on soil properties and vertical distribution of heavy metal].

    PubMed

    Zhao, Zong-Ming; Chen, Wei-Ping; Jiao, Wen-Tao; Wang, Mei-E

    2012-12-01

    Utilization of reclaimed water is one of the important methods to alleviate water shortage. The effect of reclaimed water irrigation on soil is always a concern. To understand the effect of long time reclaimed water irrigation on soil, typical farmland irrigated with reused water was selected. Soil properties and heavy metal concentration of soil and water samples were analyzed to identify the effect of the irrigation on heavy metal vertical distribution and organic matter content, total carbon, total nitrogen and pH value in soil. The results show that heavy metal contents of irrigation water used in Liangshuihe farmland are 2.5 to 10.5 times higher than that of Beiyechang farmland, and reclaimed water irrigation could cause changes of soil properties that soil organic matter content, total carbon, total nitrogen were increased and pH values were reduced. Based on the field investigation results, the soil nutrient conditions benefit from irrigate reclaimed water, however, the accumulation of heavy metal in soil could raise the risk. As a source of soil heavy metal, reclaimed water irrigation could make differences on the accumulation and mobility of soil heavy metal. Also the distribution and mobility of soil heavy metal are influenced by soil organic matter content and there are more heavy metal were taken up by plants or transferred to the deeper area in Liangshuihe farmland.

  20. The chemical species distribution and transformation of polyaluminum silicate chloride coagulant.

    PubMed

    Gao, Baoyu; Yue, Qinyan; Wang, Bingjian

    2002-02-01

    The chemical species distributions of polyaluminum silicate chloride (PASC) and polyaluminum chloride (PACl) determined by Al-Ferron complexation timed spectrophotometric and 27Al-NMR methods, respectively, have been compared and analyzed. The experimental results show that the species distribution and transformation of PASC are different from those of PACl, due to the interaction of polysilicic acid and hydrolyzed aluminum species. At the same basicity (B), the contents of, Al(b), Al13 and the monomer species Almono (also determined by 27Al-NMR) in PASC are lower than those in PACl, while the contents of Al(c) and the Alother determined by 27Al-NMR in PASC are higher than those in PACl. The differences between PASC and PACl with respect to these species enlarge as the molar ratio of Al/Si in PASC decreases. Further, in PACl the ratio of Al13 to Al(b) closes to 1.0, indicating that the amount of the two fractions are similar. In PASC, however, such an agreement does not exist at the lower B values and Al/Si molar ratios. When the B value and Al/Si molar ratios increase, however, the amount of Al13 and Al(b) species tends to close. The study findings indicate that polysilicic acid can react with hydrolyzed aluminum species to form an aluminum silicate polymer composite and result in the change in species distribution of PASC.

  1. [Chlorination transformation and volatilization of heavy metals in fly ash from the incineration during the disposal process with higher temperature].

    PubMed

    Liu, Jing-Yong; Sun, Shui-Yu

    2012-09-01

    The volatilization of heavy metals Pb, Cd, Cu and Zn were studied at 900 degrees C and 1 000 degrees C with different residence time, meanwhile the influence of chlorination agents CaCl2, MgCl2, NaCl, FeCl3 and AlCl3 on heavy metals volatilization was studied. The results showed that the volatilization of heavy metals had great differences with the volatilization rate followed the order Pb > Cd > Zn > Cu, in which the volatilization rate of Pb was more than 80% and that of Cu was less than 30%. In the thermal disposal process, the volatilization rate influenced by temperature was greater than that by the residence time, and the volatile elements Pb and Cd were particularly evident in the volatilization. After adding chlorides in fly ash, the volatilization of heavy metals changed significantly, and the volatilization rate of the low volatile elements Cu and Zn increased significantly compared with Pb and Cd. With the content of chloride increasing, the volatilization rate of heavy metals increased, but different types of chloride compounds on heavy metal transformation were quite different, in which the promotion effect of NaCl on heavy metals Cd, Zn and Cu was less than that of other chlorinating agents. The results can provide strategies for the harmless disposal and maximize resource utilization and recycling of fly ash.

  2. Distribution of rock, metals, and ices in Callisto.

    PubMed

    Anderson, J D; Schubert, G; Jacobson, R A; Lau, E L; Moore, W B; Sjogren, W L

    1998-06-05

    Radio Doppler data from a single encounter (C3) of the Galileo spacecraft with Callisto, the outermost Galilean moon of Jupiter, indicated that Callisto was probably undifferentiated. Now, similar data from a second encounter (C9) corroborate this conclusion, but more accurate data from a third encounter (C10) indicate that the rock and ice within Callisto have partially, but not completely, separated. Callisto may be differentiated into a rock-metal core less than 25 percent of Callisto's radius, an outer layer of clean ice less than 350 km thick, and a middle layer of mixed rock and ice. Models in which ice and rock are mixed all the way to the center of Callisto are also consistent with the data.

  3. Computing the Distribution of Pareto Sums Using Laplace Transformation and Stehfest Inversion

    NASA Astrophysics Data System (ADS)

    Harris, C. K.; Bourne, S. J.

    2017-05-01

    that is shared by the sum of an arbitrary number of such variables. The technique involves applying the Laplace transform to the normalized sum (which is simply the product of the Laplace transforms of the densities of the individual variables, with a suitable scaling of the Laplace variable), and then inverting it numerically using the Gaver-Stehfest algorithm. After validating the method using a number of test cases, it was applied to address the distribution of total seismic moment, and the quantiles computed for various numbers of seismic events were compared with those obtained in the literature using Monte Carlo simulation. Excellent agreement was obtained. As an application, the method was applied to the evolution of total seismic moment released by tremors due to gas production in the Groningen gas field in the northeastern Netherlands. The speed, accuracy and ease of implementation of the method allows the development of accurate correlations for constraining statistical seismological models using, for example, the maximum-likelihood method. It should also be of value in other natural processes governed by Pareto distributions with exponent less than unity.

  4. Size distribution of mist generated during metal machining.

    PubMed

    Thornburg, J; Leith, D

    2000-08-01

    Mist generated by machining processes is formed by three mechanisms: impaction, centrifugal force, and evaporation/condensation. This study characterized the size distribution of soluble and mineral oil mists that resulted from these formation mechanisms. Salient parameters influencing the particle size distributions also were identified. Variables investigated included metalworking fluid and machining characteristics. The size distribution of the mist generated on a small lathe by each mechanism was measured using an Aerosizer LD. For impaction, only the mineral oil viscosity influenced the mass median diameter of the mist. No parameter affected the geometric standard deviation. High-viscosity mineral oil mist had a mass median diameter of 6.1 microns and a geometric standard deviation of 2.0. Low-viscosity mineral oil mist had a mass median diameter of 21.9 microns and a geometric standard deviation of 2.2. The mass median diameter of the mist generated by centrifugal force depended on the type of metalworking fluid, fluid flow, and rotational speed of the lathe. Mass median diameters for low-viscosity mineral oil mist ranged from 5 to 110 microns. Mass median diameters for soluble oil mist varied between 40 and 80 microns. The average geometric standard deviation was 2.4, and was not affected by any parameter. The mass median diameter and geometric standard deviation of the mist generated by evaporation/condensation varied with the type of metalworking fluid. The mineral oil mist and soluble oil mist mass median diameters were 2.1 microns and 3.2 microns, respectively. No machining or fluid parameter was important because the mist size distribution depended on the rate of condensation, coagulation processes, and the dynamics of the apparatus. Using the size distribution data from all three mechanisms, the estimated inhalable, thoracic, and respirable fractions of the total mass generated for each metalworking fluid were 60 percent, 12 percent, and 8 percent

  5. Graphene Q-switched distributed feedback fiber lasers with narrow linewidth approaching the transform limit.

    PubMed

    Yao, B C; Rao, Y J; Huang, S W; Wu, Y; Feng, Z Y; Choi, C; Liu, H; Qi, H F; Duan, X F; Peng, G D; Wong, C W

    2017-04-03

    A compact all-in-line graphene-based distributed feedback Bragg-grating fiber laser (GDFB-FL) with narrow linewidth of hundreds kHz is demonstrated and investigated in this study. Performing as an optical saturable absorber, graphene oscillates the initially kHz linewidth DFB-FL, and generates high-quality passively Q-switched pulses. Pumped with a 980 nm continuous-wave laser, the Q-switched GDFB-FL observes ~1 μs pulse durations, with pulse energies up to ~10 nJ and approaching the transform limit. The peak power is ~600 times higher than the original DFB-FL laser. By optimizing the cavity design and the graphene material, it is predicted that fast Q-switched pulses with more than MHz repetition rates and sub-100 ns pulse durations are achievable. Such transform-limited Q-switched GDFB-FLs with narrow linewidth of sub-MHz have long coherence length, good tunability, stability, compactness and robustness, with potential impact in optical coherent communications, metrology and sensing.

  6. Aging Management Guideline for commercial nuclear power plants: Power and distribution transformers

    SciTech Connect

    Toman, G.; Gazdzinski, R.

    1994-05-01

    This Aging Management Guideline (AMG) provides recommended methods for effective detection and mitigation of age-related degradation mechanisms in power and distribution transformers important to license renewal in commercial nuclear power plants. The intent of this AMG to assist plant maintenance and operations personnel in maximizing the safe, useful life of these components. It also supports the documentation of effective aging management programs required under the License Renewal Rule 10 CFR Part 54. This AMG is presented in a manner which allows personnel responsible for performance analysis and maintenance to compare their plant-specific aging mechanisms (expected or already experienced) and aging management program activities to the more generic results and recommendations presented herein.

  7. [Synthesis of high-concentration polyaluminum chloride and its aluminium species distribution and transformation].

    PubMed

    Zhao, Hua-zhang; Cai, Gu-ping; Luan, Zhao-kun

    2004-09-01

    Using solid CaO as basification agent, the high-concentration polyaluminum chloride (PAC) was prepared by feeding total alkali at a time. The characteristics of the reaction and the distribution and transformation of the aluminium species were also studied. The experimental results show that the distinctive hydration of CaO can contribute to the high-concentration PAC whose Al concentration (Al(T)) and basicity (B) can reach 2.1 mol/L and 2.1 respectively. There is an optimal B value in any concentration of PAC, at which the Al(b) content is the highest. The optimal B value and the highest Al(b) content drops with the increasing of Al(T). The predominant reaction is the formation of Al(b) if B is less than the optimal B value, and the formation of Al(c) if B is more than the optimal B value.

  8. Transformation of Metal-Organic Frameworks/Coordination Polymers into Functional Nanostructured Materials: Experimental Approaches Based on Mechanistic Insights.

    PubMed

    Lee, Kyung Joo; Lee, Jae Hwa; Jeoung, Sungeun; Moon, Hoi Ri

    2017-10-09

    Nanostructured materials such as porous metal oxides, metal nanoparticles, porous carbons, and their composites have been intensively studied due to their applications, including energy conversion and storage devices, catalysis, and gas storage. Appropriate precursors and synthetic methods are chosen for synthesizing the target materials. About a decade ago, metal-organic frameworks (MOFs) and coordination polymers (CPs) emerged as new precursors for these nanomaterials because they contain both organic and inorganic species that can play parallel roles as both a template and a precursor under given circumstances. Thermal conversions of MOFs offer a promising toolbox for synthesizing functional nanomaterials that are difficult to obtain using conventional methods. Although understanding the conversion mechanism is important for designing MOF precursors for the synthesis of nanomaterials with desired physicochemical properties, comprehensive discussions revealing the transformation mechanism remain insufficient. This Account reviews the utilization of MOFs/CPs as precursors and their transformation into functional nanomaterials with a special emphasis on understanding the relationship between the intrinsic nature of the parent MOFs and the daughter nanomaterials while discussing various experimental approaches based on mechanistic insights. We discuss nanomaterials categorized by materials such as metal-based nanomaterials and porous carbons. For metal-based nanomaterials transformed from MOFs, the nature of metal ions in the MOF scaffolds affects the physicochemical properties of the resultant materials including the phase, composite, and morphology of nanomaterials. Organic ligands are also involved in the in situ chemical reactions with metal species during thermal conversion. We describe these conversion mechanisms by classifying the phase of metal components in the resultant materials. Along with the metal species, carbon is a major element in MOFs, and thus

  9. Metal-Organic Frameworks as Potential Platforms for Carbon Dioxide Capture and Chemical Transformation

    NASA Astrophysics Data System (ADS)

    Gao, Wenyang

    The anthropogenic carbon dioxide (CO2) emission into the atmosphere, mainly through the combustion of fossil fuels, has resulted in a balance disturbance of the carbon cycle. Overwhelming scientific evidence proves that the escalating level of atmospheric CO2 is deemed as the main culprit for global warming and climate change. It is thus imperative to develop viable CO2 capture and sequestration (CCS) technologies to reduce CO2 emissions, which is also essential to avoid the potential devastating effects in future. The drawbacks of energy-cost, corrosion and inefficiency for amine-based wet-scrubbing systems which are currently used in industry, have prompted the exploration of alternative approaches for CCS. Extensive efforts have been dedicated to the development of functional porous materials, such as activated carbons, zeolites, porous organic polymers, and metal-organic frameworks (MOFs) to capture CO2. However, these adsorbents are limited by either poor selectivity for CO2 separation from gas mixtures or low CO2 adsorption capacity. Therefore, it is still highly demanding to design next-generation adsorbent materials fulfilling the requirements of high CO2 selectivity and enough CO2 capacity, as well as high water/moisture stability under practical conditions. Metal-organic frameworks (MOFs) have been positioned at the forefront of this area as a promising type of candidate amongst various porous materials. This is triggered by the modularity and functionality of pore size, pore walls and inner surface of MOFs by use of crystal engineering approaches. In this work, several effective strategies, such as incorporating 1,2,3-triazole groups as moderate Lewis base centers into MOFs and employing flexible azamacrocycle-based ligands to build MOFs, demonstrate to be promising ways to enhance CO 2 uptake capacity and CO2 separation ability of porous MOFs. It is revealed through in-depth studies on counter-intuitive experimental observations that the local electric

  10. Compositional analysis of metal chelating materials using near-field photothermal Fourier transform infrared microspectroscopy.

    PubMed

    Moffat, Jonathan G; Mayes, Andrew G; Belton, Peter S; Craig, Duncan Q M; Reading, Mike

    2010-01-01

    Photothermal-Fourier transform-infrared (PT-FT-IR) microspectroscopy employs a thermal probe mounted in a scanning probe microscope (SPM). By placement of the tip of the probe on the surface of a solid sample, it can obtain localized IR spectra of a wide range of samples. A second mode of analysis is also available; a sample can be taken from the selected location using a technique called thermally assisted nanosampling (TAN), then a spectrum can be obtained of the nanosample while the probe is remote from the surface. We report a novel method of local compositional analysis that combines both of these types of measurement; a reagent is attached to the tip using TAN, then the reagent is placed in contact with analyte. IR spectroscopy can then be used to analyze any interaction between the reagent and surface it is placed in contact with. All of these modes of analysis were illustrated using a metal chelating agent. In the surface mode, changes to a solid bead of a chelating resin were measured using standard PT-FT-IR. In the nanosampling mode of analysis, a particle of a chelating polymer was attached to the tip of the probe using TAN and this was placed in contact with a concentrated calcium solution. Strong spectral changes were observed that mirrored those found when exposing the surface bound chelating resin bead to a solution of the same ion. A semiquantitative simulation of the PT spectrum for a chelating resin bead was achieved using a thermal diffusion model derived from photoacoustic spectroscopy indicating that semiquantitative or quantitative measurements will be possible in such a system.

  11. Functional Analysis and Discovery of Microbial Genes Transforming Metallic and Organic Pollutants: Database and Experimental Tools

    SciTech Connect

    Lawrence P. Wackett; Lynda B.M. Ellis

    2004-12-09

    Microbial functional genomics is faced with a burgeoning list of genes which are denoted as unknown or hypothetical for lack of any knowledge about their function. The majority of microbial genes encode enzymes. Enzymes are the catalysts of metabolism; catabolism, anabolism, stress responses, and many other cell functions. A major problem facing microbial functional genomics is proposed here to derive from the breadth of microbial metabolism, much of which remains undiscovered. The breadth of microbial metabolism has been surveyed by the PIs and represented according to reaction types on the University of Minnesota Biocatalysis/Biodegradation Database (UM-BBD): http://umbbd.ahc.umn.edu/search/FuncGrps.html The database depicts metabolism of 49 chemical functional groups, representing most of current knowledge. Twice that number of chemical groups are proposed here to be metabolized by microbes. Thus, at least 50% of the unique biochemical reactions catalyzed by microbes remain undiscovered. This further suggests that many unknown and hypothetical genes encode functions yet undiscovered. This gap will be partly filled by the current proposal. The UM-BBD will be greatly expanded as a resource for microbial functional genomics. Computational methods will be developed to predict microbial metabolism which is not yet discovered. Moreover, a concentrated effort to discover new microbial metabolism will be conducted. The research will focus on metabolism of direct interest to DOE, dealing with the transformation of metals, metalloids, organometallics and toxic organics. This is precisely the type of metabolism which has been characterized most poorly to date. Moreover, these studies will directly impact functional genomic analysis of DOE-relevant genomes.

  12. [Distribution of heavy metals in Xiangsi River Valley of Tongling, China].

    PubMed

    Chen, Li-Wei; Xu, Xiao-Chun; Wang, Jun; Chen, Fang

    2014-08-01

    The Xiangsi River valley was selected to study the distribution of heavy metals in mining area. Waste rocks, soils, sediments and waters of Xiangsi River valley were sampled. The concentrations of Cu, Pb, Zn, Cd, Cr, As and Hg were analyzed. The possibility of generating acid drainage of the waste rocks was studied. Meanwhile, the speciation of Pb and Cr in waste rocks was analyzed by the five-step sequential chemical extract method developed by Fŏrtsner. And then the distribution of heavy metals in various samples was summarized, and the ecological risk of heavy metals in mining area was discussed. The results indicated that the waste rocks of Fenghuangshan copper mine upriver barely generated acid mine drainage (AMD). But the waste rocks of Xinqiao pyrite mine in the middle area generated AMD. The content of sulfide mineral rich of heavy metals was lower and the content of CaO was higher in the waste rocks of Fenghuangshan copper mine, resulting in the different AMD generation ability. The contents of heavy metals in waste rocks were higher, and the deoxidization of Pb and Cr was positively correlated with their concentrations in waste rocks. The results indicated that heavy metals in waste rocks would be most likely dissolved in AMD and then contaminate the environment. There was obvious regularity in the distributions of heavy metals in soils, sediments and waters of Xiangsi river valley. The concentrations of heavy metals upriver were lower than those of corresponding national standards and elements background values. But there was obvious heavy metal contamination in the middle area. It was shown that the mining activities of Xinqiao pyrite mine in the middle area had ecological harm to the surrounding environment. And mining enterprises should pay attention to the emissions of mining wastes and the treatment of AMD.

  13. Distribution of seven heavy metals among hot pepper plant parts.

    PubMed

    Antonious, George F

    2016-01-01

    The main objective of this investigation was to monitor concentrations of seven metals (Cd, Pb, Ni, Mo, Cu, Zn, and Cr) in the fruits, leaves, stem, and roots of Capsicum annuum L. (cv. Xcatic) plants grown under four soil management practices: yard waste (YW), sewage sludge (SS), chicken manure (CM), and no-much (NM) bare soil. Elemental analyses were conducted using inductively coupled plasma mass spectrometer. Pb and Cd concentrations in soil amended with YW, SS, and CM were not significantly different (P < 0.05) compared to NM soil, whereas Mo and Cu concentrations were significantly greater in YW compared to SS, CM, and NM treatments. Concentrations of Cd in the fruits of plants grown in NM soil were greater compared to the fruits of plants grown in other treatments. Total Ni concentration (sum of Ni in all plant parts) in plants grown in NM bare soil was greater than in plants grown in SS-, YW-, and CM-amended soils. Values of the bioaccumulation factor indicated that pepper fruits of plants grown in YW, SS, and CM did not show any tendency to accumulate Pb, Cr, and Ni in their edible fruits.

  14. Distribution patterns of the metal pollutants Cd and Ni in soybean seeds

    NASA Astrophysics Data System (ADS)

    Malan, H. L.; Mesjasz-Przybylowicz, J.; Przybylowicz, W. J.; Farrant, J. M.; Linder, P. W.

    2012-02-01

    Soybean ( Glycine max) plants were grown to maturity in nutrient solution, amended with either Cd or Ni. The distribution of these metals in mature seeds was examined with micro-PIXE. The levels of Cd were too low for mapping and only average concentrations from selected regions could be obtained. Cd was localised mainly in the seed coat and cotyledons, with very little in the embryo axis. Levels of Ni were high enough to obtain the distribution maps. This metal was mainly concentrated in the axis, particularly in the apical meristem and cortex, and least in the cotyledons. Localisation of Ni within different tissues of the embryo was facilitated by mapping of Ca which is present in the cell walls of plants. This enabled the different plant tissues of the seed embryo to be identified. Micro-PIXE is a valuable tool for localising the distribution of metal pollutants in plant tissue.

  15. Heavy metals distribution and contamination in surface sediments of the coastal Shandong Peninsula (Yellow Sea).

    PubMed

    Li, Guogang; Hu, Bangqi; Bi, Jianqiang; Leng, Qinuan; Xiao, Chunqiao; Yang, Zhongcheng

    2013-11-15

    Selected heavy metals (Cr, Cu, Ni, Pb and Zn) in surface sediments from the coastal Shandong Peninsula (Yellow Sea) have been determined to evaluate the spatial distribution and potential ecological risk. Results showed that heavy metal concentrations in the sediments generally met the criteria of China Marine Sediment Quality. However, both the enrichment factor (EF) and geoaccumulation index (Igeo) values suggested the elevation of Pb concentration in the region. Based on the effect-range classification (TEL-PEL SQGs), Cr, Cu and Ni were likely to pose environment risks. Spatial distribution of ecotoxicological index (mean-PEL-quotient) suggested that most of the surface sediments have a 21% probability of being toxic. Similar results were also obtained by pollution load index (PLI). The spatial distribution pattern of heavy metal in surface sediments is a basis for undertaking appropriate action to protect marine sediment quality.

  16. [Soil Heavy Metal Spatial Distribution and Source Analysis Around an Aluminum Plant in Baotou].

    PubMed

    Zhang, Lian-ke; Li, Hai-peng; Huang, Xue-min; Li, Yu-mei; Jiao, Kun-ling; Sun, Peng; Wang, Wei-da

    2016-03-15

    The soil with 500 m distance from an aluminum plant in Baotou was studied. A total of 64 soil samples were taken from the 0-5 cm, 5-20 cm, 20-40 cm and 40-60 cm layers, and the contents of Cu, Pb, Zn, Cr, Cd, Ni and Mn were tested, respectively. The correlation analysis and principal component analysis were used to identify the sources of these heavy metals in soils. The results suggested that the contents of Cu, Pb, Zn, Cr, Cd, Ni and Mn in study area were 32.9, 50.35, 69.92, 43.78, 0.54, 554.42 and 36.65 mg · kg⁻¹ respectively. All seven heavy metals tested were overweight compared with the background values of soil in Inner Mongolia. The spatial distribution of heavy metals showed that the horizontal distribution of heavy metals was obviously enriched in the southwest, while in vertical distribution, the heavy metal content (0 to 5 cm) was highest in the surface soil, and the heavy metal content decreased with increasing depth and tended to be stabilized when the depth was over 20 cm. Source analysis showed that the source of Cu, Zn, Cr and Mn might be influenced by the aluminum plant and the surrounding industrial activity. The source of Pb and Cd might be mainly related to road transportation. The source of Ni may be affected by agricultural activities and soil parent material together.

  17. Heavy metals distribution in the sediments of ganges and Brahmaputra rivers

    NASA Astrophysics Data System (ADS)

    Subramanian, V.; van Grieken, R.; van't Dack, L.

    1987-06-01

    Bed sediments were collected from the entire region of the Ganges basin and some parts of the Brahmaputra. In addition, selected stations were sampled for suspended sediments as well. The samples were analysed for a number of heavy metals (Fe, Mn, Ni, Cr, Cu, and Zn) by the thin-film energy dispersive X-ray fluorescence technique. There are pronounced temporal and spatial variations in the heavy metals distributions. Suspended sediments are 5-10 times richer than the bed sediments. None of the tributaries contribute significant heavy metal load, but around urban areas in Yamuna (tributary of Ganges), very high levels due to the distribution from the drainage network are observed. Compared to the Brahmaputra, the distribution and fractionation of heavy metals in the Ganges sediments are more erratic and highly variable. All the metals considered show high correlation among themselves. Given the high flux of suspended sediments from the Himalayan rivers (nearly 20% of the global flux), the worldwide budget for heavy metal transport may need to be suitably revised.

  18. Heavy metals distribution in the sediments of Ganges and Brahmaputra Rivers

    SciTech Connect

    Subramanian, V. ); Van Grieken, R.; Van't Dack, L. )

    1987-01-01

    Bed sediments were collected from the entire region of the Ganges basin and some parts of the Brahmaputra. In addition, selected stations were sampled for suspended sediments as well. The samples were analyzed for a number of heavy metals (Fe, Mn, Ni, Cr, Cu, and Zn) by the thin-film energy dispersive X-ray fluorescence technique. There are pronounced temporal and spatial variations in the heavy metals distributions. Suspended sediments are 5-10 times richer than the bed sediments. None of the tributaries contribute significant heavy metal load, but around urban areas in Yamuna (tributary of Ganges), very high levels due to the distribution from the drainage network are observed. Compared to the Brahmaputra, the distribution and fractionation of heavy metals in the Ganges sediments are more erratic and highly variable. All the metals considered show high correlation among themselves. Given the high flux of suspended sediments from the Himalayan rivers (nearly 20% of the global flux), the worldwide budget for heavy metal transport may need to be suitable revised.

  19. Metal Immobilization on Wood-Derived Biochars: Distribution and Reactivity of Carbonate Phases.

    PubMed

    Rees, Frédéric; Watteau, Françoise; Mathieu, Sandrine; Turpault, Marie-Pierre; Le Brech, Yann; Qiu, Rongliang; Morel, Jean Louis

    2017-07-01

    Metals can be immobilized on biochars by precipitation with carbonate. The distribution of metal-carbonate phases at the surface of biochars and the conditions of their formation, however, are unknown. Electron microscopy and X-photon spectroscopy were used to characterize carbonate phases in various morphological groups of particles of a wood-derived biochar, both before and after a metal-sorption experiment. Our results showed that the distribution of metals at the surface of biochar particles depended on the corresponding wood tissues and the presence of carbonate phases. Metals were particularly concentrated (i) within calcium carbonate crystals in bark-derived particles, which originated from calcium oxalate crystals formed prior to pyrolysis, and (ii) as new phases formed by the reprecipitation of carbonate on specific tissues of biochar. The formation of biochar carbonate phases and their redistribution by dissolution-precipitation mechanisms may primarily control the localization of metals on biochar particles and the durability of metals immobilization. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

  20. Assessment of spatial distribution of soil heavy metals using ANN-GA, MSLR and satellite imagery.

    PubMed

    Naderi, Arman; Delavar, Mohammad Amir; Kaboudin, Babak; Askari, Mohammad Sadegh

    2017-05-01

    This study aims to assess and compare heavy metal distribution models developed using stepwise multiple linear regression (MSLR) and neural network-genetic algorithm model (ANN-GA) based on satellite imagery. The source identification of heavy metals was also explored using local Moran index. Soil samples (n = 300) were collected based on a grid and pH, organic matter, clay, iron oxide contents cadmium (Cd), lead (Pb) and zinc (Zn) concentrations were determined for each sample. Visible/near-infrared reflectance (VNIR) within the electromagnetic ranges of satellite imagery was applied to estimate heavy metal concentrations in the soil using MSLR and ANN-GA models. The models were evaluated and ANN-GA model demonstrated higher accuracy, and the autocorrelation results showed higher significant clusters of heavy metals around the industrial zone. The higher concentration of Cd, Pb and Zn was noted under industrial lands and irrigation farming in comparison to barren and dryland farming. Accumulation of industrial wastes in roads and streams was identified as main sources of pollution, and the concentration of soil heavy metals was reduced by increasing the distance from these sources. In comparison to MLSR, ANN-GA provided a more accurate indirect assessment of heavy metal concentrations in highly polluted soils. The clustering analysis provided reliable information about the spatial distribution of soil heavy metals and their sources.

  1. Fate and Distribution of Heavy Metals in Wastewater Irrigated Calcareous Soils

    PubMed Central

    Stietiya, Mohammed Hashem; Duqqah, Mohammad; Udeigwe, Theophilus; Zubi, Ruba; Ammari, Tarek

    2014-01-01

    Accumulation of heavy metals in Jordanian soils irrigated with treated wastewater threatens agricultural sustainability. This study was carried out to investigate the environmental fate of Zn, Ni, and Cd in calcareous soils irrigated with treated wastewater and to elucidate the impact of hydrous ferric oxide (HFO) amendment on metal redistribution among soil fractions. Results showed that sorption capacity for Zarqa River (ZR1) soil was higher than Wadi Dhuleil (WD1) soil for all metals. The order of sorption affinity for WD1 was in the decreasing order of Ni > Zn > Cd, consistent with electrostatic attraction and indication of weak association with soil constituents. Following metal addition, Zn and Ni were distributed among the carbonate and Fe/Mn oxide fractions, while Cd was distributed among the exchangeable and carbonate fractions in both soils. Amending soils with 3% HFO did not increase the concentration of metals associated with the Fe/Mn oxide fraction or impact metal redistribution. The study suggests that carbonates control the mobility and bioavailability of Zn, Ni, and Cd in these calcareous soils, even in presence of a strong adsorbent such as HFO. Thus, it can be inferred that in situ heavy metal remediation of these highly calcareous soils using iron oxide compounds could be ineffective. PMID:24723833

  2. Grain size effect on trace metals distribution in sediments from two coastal areas of Chile

    SciTech Connect

    I. De Gregori, H.; H. Pinochet, C.; M. Arancibia, J.; A. Vidal, B.

    1996-07-01

    Marine environment contamination by trace metals has received increased global attention during recent years. Presently it is widely recognized that marine ecosystem can become contaminated by trace metals from numerous and diverse sources. However, anthropogenic activities, such as mining and industrial processing of ores and metals, still remain the principal cause of the increased amount of heavy metals which have been dumped into oceans. After entering the aquatic environment trace metals are distributed among water, biotic and sediment compartments, this latter serving as a final sink for metal pollutants. The magnitude of this scavenging action of sediments depends on the physical, chemical and biological properties of the sediments. Concentrations of trace metals in sediments are usually of a greater magnitude order than concentrations in water. Sediments were considered as an important indicator for environmental pollution, they act as permanent or temporary traps for material spread into the environment. The purpose of this study was to determine the grain size effect on the copper, cadmium and zinc levels distribution in surface marine sediments along the Chilean Coast. 18 refs., 1 fig., 1 tab.

  3. Improving the sensitivity of a high-Tc SQUID at MHz frequency using a normal metal transformer

    NASA Astrophysics Data System (ADS)

    He, D. F.; Itozaki, H.; Tachiki, M.

    2006-05-01

    Superconducting quantum interference devices (SQUIDs) can be used to detect the signals of nuclear quadrupole resonance (NQR). The NQR frequencies of some interesting materials are in the order of MHz. However, the sensitivity of a high-Tc SQUID is normally not enough to detect the weak NQR signals. To improve the sensitivity of a high-Tc SQUID at MHz frequency, we used a transformer made of normal copper wire. The transformer was composed of a pickup coil, an input coil and a capacitor. The pickup coil was used to detect the magnetic field; the input coil was used to couple the field to the SQUID; and the capacitor was used to create a resonant frequency. By using the normal metal transformer, the magnetic field resolution of the high-Tc dc SQUID was improved by about 38.8 times (from 220 to 5.67 fT Hz-1/2) at 954 kHz.

  4. The migration and transformation behavior of heavy metals during the liquefaction process of sewage sludge.

    PubMed

    Leng, Lijian; Yuan, Xingzhong; Huang, Huajun; Jiang, Hongwei; Chen, Xiaohong; Zeng, Guangming

    2014-09-01

    Bio-oils and bio-chars were obtained from sewage sludge (SS) by liquefaction with ethanol (or acetone) as the solvent at the temperature of 280, 320 and 360°C. The migration and transformation of HMs as Pb, Zn, Cu and Ni during liquefaction were thoroughly investigated. Meanwhile, the environmental risk of HMs in the bio-oils and bio-chars was assessed according to the risk assessment code (RAC). The results showed that the liquefaction solvent and temperature significantly affected the redistribution of HMs. HMs distributed mainly into the bio-chars, with less than 10% into the bio-oils. Increasing liquefaction temperature would promote a higher HM content in bio-oils. The environmental risk of HMs in bio-chars was mitigated compared to SS, especially for Ni. However, the environmental risk of Zn and Ni in bio-oils was undesirably high in comparison with bio-chars. It was suggested that the bio-oil should be pretreated before utilization. Copyright © 2014 Elsevier Ltd. All rights reserved.

  5. Factors controlling metal distributions in the surface sediments of the Erdek Bay, Sea of Marmara, Turkey.

    PubMed

    Balkis, N; Cağatay, M N

    2001-07-01

    A geochemical study of the Erdek Bay sediments in the Sea of Marmara, Turkey, was carried out to investigate the heavy metal distributions and sources. The bay has an average depth of 34 m and a two-layer water column stratification, with a pycnocline at 20 m. The distribution of "total" metal (Fe, Mn, Pb, Cu, Ni, Cr, Zn and Hg) concentrations, together with sequential selective extraction analyses, shows that the relatively high metal concentrations are mainly due to land-based natural inputs from the erosion products of mineralized zones and mafic-ultramafic rocks delivered to the bay by two rivers from the south. However, some Pb, Zn and Cu occur in the Fe-Mn-oxyhydroxide and organic fractions, suggesting, in part, some anthropogenic inputs in addition to the predominantly natural inputs. The vertical distribution of metal/A1 ratios in a gravity core in the bay shows no significant change with depth, except for an early diagenetic enrichment at 0.7-1.6 m below sea floor (mbsf) above a 4750-3500-year-old sapropelic layer. This distribution is a further indication of the insignificant antropogenic metal pollution in the bay.

  6. [The effect of solid phase transformation on the metal-ceramic compatibility of Co-Cr alloy].

    PubMed

    Wu, Zhikai; Xu, Sheng; Li, Ning

    2011-12-01

    To study the effect of solid phase transformation on the metal-ceramic compatibility of Co-Cr alloy during firing programs. 9 foils of Co-Cr and Ni-Cr alloy with the dimension of 25 mmx3 mmx0.5 mm were casted using lost wax technology respectively. Among them, 6 specimens were subjected to metal-ceramic bonding strength test (three point bending method), the ceramic layer of 3 specimens were removed for X-ray diffraction (XRD) analysis. One cylindrical specimen of each alloy was casted for the test of coefficient of thermal expansion, cooling curves were recorded. The metal-ceramic bonding strength of Ni-Cr, Co-Cr alloy was (49.1 +/- 3.40), (40.9 +/- 2.02) MPa respectively. There was significant difference between the two groups' bonding strength (P = 0.00). The coefficient of thermal expansion in the 20-500 degrees C interval of Ni-Cr and Co-Cr alloy was 13.9 x 10(-6), 13.8 x 10(-6) x K(-1) respectively. XRD analysis indicated that the microstructure of Ni-Cr alloy was austenite. While Co-Cr alloy was constituted by fcc phase, hcp phase and sigma phase. During the cooling procedure, the transformation of fcc phase to hcp phase and segregation of needle-like sigma phase intensify the linear contraction speed of Co-Cr alloy, which decreases the metal-ceramic adaptability.

  7. Angular distribution of atoms ejected by laser ablation of different metals

    SciTech Connect

    Konomi, I.; Motohiro, T.; Asaoka, T.

    2009-07-01

    Angular distributions of 13 different metals ejected by laser ablation using fourth harmonics (wavelength=266 nm) of neodymium doped yttrium aluminum garnet laser and a fluence close to near-threshold value (2.3 J/cm{sup 2}) have been investigated with a high angular resolution. The angular distribution which is characterized by the exponent n of cos{sup n} theta distribution showed very broad range of values between 3 and 24 for different metals. A simple relation that the exponent n is proportional to the square root of particle atomic weight as reported previously has not been observed. Instead, a general trend has been found that the metals with higher sublimation energy such as Ta and Zr show narrower angular distribution than those with lower sublimation energy such as Sn and In. While the sublimation energy of metals has a great influence on the angular distribution of ejected atoms, a simple consideration suggests that their thermal conductivity and specific heat have little effect on it.

  8. Characterization and distribution of metal and nonmetal elements in the Alberta oil sands region of Canada.

    PubMed

    Huang, Rongfu; McPhedran, Kerry N; Yang, Lingling; El-Din, Mohamed Gamal

    2016-03-01

    This review covers the characterization and distribution of metals and nonmetals in the Alberta oil sands region (AOSR) of Canada. The development of the oil sands industry has resulted in the release of organic, metal and nonmetal contaminants via air and water to the AOSR. For air, studies have found that atmospheric deposition of metals in the AOSR decreased exponentially with distance from the industrial emission sources. For water, toxic metal concentrations often exceeded safe levels leading to the potential for negative impacts to the receiving aquatic environments. Interestingly, although atmospheric deposition, surface waters, fish tissues, and aquatic bird eggs exhibited increasing level of metals in the AOSR, reported results from river sediments showed no increases over time. This could be attributed to physical and/or chemical dynamics of the river system to transport metals to downstream. The monitoring of the airborne emissions of relevant nonmetals (nitrogen and sulphur species) was also considered over the AOSR. These species were found to be increasing along with the oil sands developments with the resultant depositions contributing to nitrogen and sulphur accumulations resulting in ecosystem acidification and eutrophication impacts. In addition to direct monitoring of metals/nonmetals, tracing of air emissions using isotopes was also discussed. Further investigation and characterization of metals/nonmetals emissions in the AOSR are needed to determine their impacts to the ecosystem and to assess the need for further treatment measures to limit their continued output into the receiving environments. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. Uptake and distribution of metals by water lettuce (Pistia stratiotes L.).

    PubMed

    Lu, Qin; He, Zhenli L; Graetz, Donald A; Stoffella, Peter J; Yang, Xiaoe

    2011-07-01

    Water quality impairment by heavy metal contamination is on the rise worldwide. Phytoremediation technology has been increasingly applied to remediate wastewater and stormwater polluted by heavy metals. Laboratory analysis and field trials were conducted to evaluate the uptake of metals (Al, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Pb, and Zn) by an aquatic plant, water lettuce (Pistia stratiotes L.), and metal distribution in the plant. The growth of water lettuce reduced Al, Fe, and Mn concentrations in water by >20%, K and Cu by >10%, and Ca, Mg, Zn, and Na to a lesser extent. A larger proportion of Ca, Cd, Co, Fe, Mg, Mn, and Zn was adsorbed or deposited on the external root surfaces while more Al, Cr, Cu, Ni, and Pb were absorbed and accumulated within the roots. Water lettuce has a great ability in concentrating metals from its surrounding water with a concentration factor (CF) ≥10(2). The bio-concentration factor (BCF), which excludes the part on the root surfaces, is a more appropriate index than the CF for the differentiation of hyperaccumulation, accumulation, or non-accumulation plants for metals. Water lettuce is a hyperaccumulator for Cr, Cu, Fe, Mn, Ni, Pb, and Zn and can be applied for the remediation of surface waters. Further study on the bioavailability of metals in the water lettuce is needed for the beneficial use of metal-enriched plant biomass.

  10. Determination of selected heavy metal concentrations and distribution in a southwestern stream using macrophytes.

    PubMed

    Martinez, Edward A; Shu-Nyamboli, Chemanji

    2011-09-01

    Since the reduction of the arsenic standard from 50 to 10 μg L(-1) by the US Environmental Protection Agency in 2006 many small town and rural water municipalities were left with the task of preventing or mitigating arsenic contamination of drinking water supplies. In this study macrophytes and sediments were used to determine the concentration and distribution of heavy metals (As, Cd, Cu, Pb, and Zn) within the primary source of drinking water (Gallinas River watershed) to the residents of Las Vegas, New Mexico. Sampling was done in the spring and fall at four sites, two above the city and two below, and samples were analyzed using ICP-MS. Results showed significantly higher (p<.05) metal concentrations in plant roots than shoots for most metals. Spearman's correlation showed positive correlations (r>.3) between plant and sediment concentrations of Cd, Pb, Zn, As, and a negative correlation for Cu. The site above waste water treatment plant (AWWTP) had the highest plant tissue concentrations of Cd, Pb, Zn, and As. All of these concentrations attained critical toxicity levels exceeding sediment quality guidelines. High concentration factor values and levels of metals detected in macrophyte tissues indicate that heavy metals within sediments in the Gallinas River occur in bioavailable forms. Correlations between plant and sediment metal concentrations indicate that metal concentrations in macrophyte tissues are a good reflection of metal concentrations within the sediment in the Gallinas River. Copyright © 2011 Elsevier Inc. All rights reserved.

  11. The seasonal influence on the spatial distribution of dissolved selected metals in Lake Naivasha, Kenya

    NASA Astrophysics Data System (ADS)

    Kamau, Joseph Nyingi; Gachanja, Anthony; Ngila, Catherine; Kazungu, Johnson Michael; Zhai, Mingzhe

    Lake Naivasha is the only freshwater Lake in Rift Valley, in Kenya. It lies in a fertile semi-arid basin. The Lake has no surface water outlet and is presumed to be under stress. Dissolved metals are directly taken up by bacteria, algae, plants, and planktonic and benthic organisms. Dissolved metals can also adsorb to particulate matter in water column and enter aquatic organisms through various routes. Cadmium, copper, lead and zinc may bioaccumulate within lower organisms, yet they do not biomagnify up the food chain as do mercury and selenium. This study reports on the levels and distribution of dissolved heavy metals and investigates the influence of physicochemical parameters on metal mobilization. The bioavailability of selected metals was investigated by relating the levels of dissolved metals to that in fish. Water abstraction for irrigation and domestic use, compounded with organic matter inflow will affect physicochemical parameters and hence influences the mobilization of heavy metals. Dissolved Zn correlated highly with sediment pH (r = 0.67) indicating that dissolution increases with increase in pH. In addition, the fact that the pH also correlated positively with organic matter r = 0.50, Eh r = 0.63, temperature r = 0.56 and dissolved oxygen r = 56, would suggest that organic bound Zn contributed significantly to the concentration of dissolved Zn. In situ flux experiments indicated that the fringing papyrus reeds located along the shores of Lake Naivasha provided sites for metal immobilization due to their coprecipitation on redox sensitive.

  12. Heavy metal distribution of natural and reclaimed tidal riparian wetlands in south estuary, China.

    PubMed

    Zhang, Honggang; Cui, Baoshan; Zhang, Kejiang

    2011-01-01

    We evaluated the distribution and accumulation of Cd, Cr, Cu, Ni, Pb and Zn in two plant species (Scirpus tripueter Linn. and Cyperus malaccensis Lam.), in water and soils sampled from the reclaimed tidal riparian wetlands (RTRWs) and the natural riparian wetlands (NRWs) in the Pearl River Estuary (PRE). The results showed that the concentrations of studied heavy metals in soils exceeded the eco-toxic threshold recommended by US EPA. The concentrations of Cd, Cr and Zn in plants may lead to toxic effects. The heavy metal concentrations were high in water and low in soils of RTRWs compared with that in the NRWs. The accumulation of heavy metals in the roots of plants was higher in NRWs than those in RTRWs while the opposite result was found for heavy metal accumulation in shoots. Based on the bioaccumulation and translocation factors, the plants in NRWs had a higher capacity to accumulate heavy metals while higher abilities to transport heavy metals from roots to shoots were observed in RTRWs. Heavy metal contaminations in RTRWs were dominated by anthropogenic sources from both side uplands and river water, whereas in NRWs, the metal accumulations were simultaneously affected by anthropogenic and natural factors

  13. Reversible effects of sphingomyelin degradation on cholesterol distribution and metabolism in fibroblasts and transformed neuroblastoma cells.

    PubMed Central

    Pörn, M I; Slotte, J P

    1990-01-01

    Plasma-membrane sphingomyelin appears to be one of the major determinants of the preferential allocation of cell cholesterol into the plasma-membrane compartment, since removal of sphingomyelin leads to a dramatic redistribution of cholesterol within the cell [Slotte & Bierman (1988) Biochem. J. 250, 653-658]. In the present study we examined the long-term effects of sphingomyelin degradation on cholesterol redistribution in cells and determined the reversibility of the process. In a human lung fibroblast-cell line, removal of 80% of the sphingomyelin led to a rapid and transient up-regulation (3-fold) of acyl-CoA:cholesterol acyltransferase (ACAT) activity, and also, within 30 h, to the translocation of about 50% of the cell non-esterified cholesterol from a cholesterol oxidase-susceptible compartment (i.e. the cell surface) to oxidase-resistant compartments. At 49 h after the initial sphingomyelin degradation, the cell sphingomyelin level was back to 45% of the control level, and the direction of cell cholesterol flow was toward the cell surface, although the original distribution was not achieved. In a transformed neuroblastoma cell line (SH-SY5Y), the depletion of sphingomyelin led to a similarly rapid and transient up-regulation of ACAT activity, and to the translocation of about 25% of cell-surface cholesterol into internal membranes (within 3 h). The flow of cholesterol back to the cholesterol oxidase-susceptible pool was rapid, and a pretreatment cholesterol distribution was reached within 20-49 h. Also, the resynthesis of sphingomyelin was faster in SH-SY5Y neuroblastoma cells and reached control levels within 24 h. The findings of the present study show that the cellular redistribution of cholesterol, as induced by sphingomyelin degradation, is reversible and suggest that the normalization of cellular cholesterol distribution is linked to the re-synthesis of sphingomyelin. PMID:2222406

  14. The Cosmic Evolution of the Metallicity Distribution of Ionized Gas Traced by Lyman Limit Systems

    NASA Astrophysics Data System (ADS)

    Lehner, Nicolas; O'Meara, John M.; Howk, J. Christopher; Prochaska, J. Xavier; Fumagalli, Michele

    2016-12-01

    We present the first results from our KODIAQ Z survey aimed at determining the metallicity distribution and physical properties of the z≳ 2 partial and full Lyman limit systems (pLLSs and LLSs; 16.2≤slant {log}{N}{{H}{{I}}}\\lt 19), which are probed of the interface regions between the intergalactic medium (IGM) and galaxies. We study 31 H i-selected pLLSs and LLSs at 2.3\\lt z\\lt 3.3 observed with Keck/HIRES in absorption against background QSOs. We compare the column densities of metal ions to H i and use photoionization models to assess the metallicity. The metallicity distribution of the pLLSs/LLSs at 2.3\\lt z\\lt 3.3 is consistent with a unimodal distribution peaking at [{{X}}/{{H}}]≃ -2. The metallicity distribution of these absorbers therefore evolves markedly with z since at z≲ 1 it is bimodal with peaks at [{{X}}/{{H}}]≃ -1.8 and -0.3. There is a substantial fraction (25%-41%) of pLLSs/LLSs with metallicities well below those of damped Lyα absorbers (DLAs) at any studied z from z≲ 1 to z˜ 2-4, implying reservoirs of metal-poor, cool, dense gas in the IGM/galaxy interface at all z. However, the gas probed by pLLSs and LLSs is rarely pristine, with a fraction of 3%-18% for pLLSs/LLSs with [{{X}}/{{H}}]≤slant -3. We find C/α enhancement in several pLLSs and LLSs in the metallicity range -2≲ [{{X}}/{{H}}]≲ -0.5, where C/α is 2-5 times larger than observed in Galactic metal-poor stars or high-redshift DLAs at similar metallicities. This is likely caused by preferential ejection of carbon from metal-poor galaxies into their surroundings.

  15. Effects of drip irrigation on migration and distribution of heavy metals in soil profile.

    PubMed

    Wei, Binggan; Yu, Jiangping; Dong, Yunshe; Yang, Linsheng; Wang, Jing; Xue, Yuan; Guo, Shufang

    2016-02-01

    Drip irrigation systems have been widely applied in semiarid and arid regions of China. However, little is known about the migration of heavy metals in cultivated soil under drip irrigation. Therefore, the concentrations of Cd, Cr, Cu, Ni, Pb, and Zn in soil were determined. The mean contents of Cd, Cr, Cu, Pb, Zn, and Ni in surface soil subjected to irrigation with low and high amounts of water (W1 and W2) were 0.11, 117.50, 37.51, 13.53, 78.10, and 38.41 mg/kg and 0.20, 94.45, 29.71, 22.48, 63.00, and 36.62 mg/kg, respectively. Metal concentrations in deep soil varied slightly between W1 and W2. Among different distances from the dropper, the metal levels in surface soil varied widely, while they varied slightly in deep soil. The Igeo (geo-accumulation index) values indicated that the soil was usually contaminated by Cr, Cu, and Cd. Under W1, Cd and Cu usually accumulated in surface soil near the dropper, while the other metals leached into subsurface soil. Moreover, the metals generally accumulated in soil away from the dropper. However, significant leaching of metals to the subsurface and deep soil was observed near the dropper under W2. Away from the dropper, Cd, Cr, Cu, Ni, and Pb usually accumulated in surface and deep soil. This suggested that heavy metals generally migrated to the soil away from the dropper when subjected to lower amounts of irrigation, while metals usually moved to surface soil and deep soil under high irrigation amounts. These findings indicate that drip irrigation greatly affected the distribution and migration of heavy metals in soil, with irrigation with lower amounts of irrigation water significantly affecting the horizontal migration of heavy metals and higher amounts influencing the vertical movement of heavy metals.

  16. THE BIMODAL METALLICITY DISTRIBUTION OF THE COOL CIRCUMGALACTIC MEDIUM AT z {approx}< 1

    SciTech Connect

    Lehner, N.; Howk, J. C.; Tripp, T. M.; Tumlinson, J.; Thom, C.; Fox, A. J.; Prochaska, J. X.; Werk, J. K.; Ribaudo, J.

    2013-06-20

    We assess the metal content of the cool ({approx}10{sup 4} K) circumgalactic medium (CGM) about galaxies at z {approx}< 1 using an H I-selected sample of 28 Lyman limit systems (LLS; defined here as absorbers with 16.2 {approx}< log N{sub H{sub I}} {approx}< 18.5) observed in absorption against background QSOs by the Cosmic Origins Spectrograph on board the Hubble Space Telescope. The N{sub H{sub I}} selection avoids metallicity biases inherent in many previous studies of the low-redshift CGM. We compare the column densities of weakly ionized metal species (e.g., O II, Si II, Mg II) to N{sub H{sub I}} in the strongest H I component of each absorber. We find that the metallicity distribution of the LLS (and hence the cool CGM) is bimodal with metal-poor and metal-rich branches peaking at [X/H] {approx_equal} -1.6 and -0.3 (or about 2.5% and 50% solar metallicities). The cool CGM probed by these LLS is predominantly ionized. The metal-rich branch of the population likely traces winds, recycled outflows, and tidally stripped gas; the metal-poor branch has properties consistent with cold accretion streams thought to be a major source of fresh gas for star forming galaxies. Both branches have a nearly equal number of absorbers. Our results thus demonstrate there is a significant mass of previously undiscovered cold metal-poor gas and confirm the presence of metal enriched gas in the CGM of z {approx}< 1 galaxies.

  17. The effect of low-temperature transformation of mixtures of sewage sludge and plant materials on content, leachability and toxicity of heavy metals.

    PubMed

    Gondek, Krzysztof; Baran, Agnieszka; Kopeć, Michał

    2014-12-01

    The aim of the study was to determine the influence of the process of low-temperature transformation and the addition of plant material to sewage sludge diversifying the content of mobile forms of heavy metals and their ecotoxicity. The experimental design included: sewage sludge+rape straw, sewage sludge+wheat straw, sewage sludge+sawdust, sewage sludge+bark and sewage sludge with no addition. The mixtures were subjected to thermal transformation in a chamber furnace, under conditions without air. The procedure consisted of two stages: the first stage (130°C for 40 min) focused on drying the material, whereas in the second stage (200°C for 30 min) proper thermal transformation of materials took place. Thermal transformation of the materials, caused an increase in total contents of heavy metals in comparison to the material before transformation. From among elements, the cadmium content changed the most in materials after thermal transformation. As a result of thermal transformation, the content of water soluble form of the heavy metals decreased significantly in all the prepared mixtures. Low toxicity of the extracts from materials for Vibrio fischeri and Lepidium sativum was found in the research, regardless of transformation process. L. sativum showed higher sensitivity to heavy metals occurring in the studied extracts from materials than V. fischeri, evidence of which are the positive significant correlations between the content of metals and the inhibition of root growth of L. sativum.

  18. Distribution and health risk assessment to heavy metals near smelting and mining areas of Hezhang, China.

    PubMed

    Briki, Meryem; Zhu, Yi; Gao, Yang; Shao, Mengmeng; Ding, Huaijian; Ji, Hongbing

    2017-08-19

    Mining and smelting areas in Hezhang have generated a large amount of heavy metals into the environment. For that cause, an evaluative study on human exposure to heavy metals including Co, Ni, Cu, Zn, Cr, As, Cd, Pb, Sb, Bi, Be, and Hg in hair and urine was conducted for their concentrations and correlations. Daily exposure and non-carcinogenic and carcinogenic risk were estimated. Sixty-eight scalp hair and 66 urine samples were taken from participants of different ages (6-17, 18-40, 41-60, and ≥ 65 years) living in the vicinity of an agricultural soil near mine and smelting areas. The results compared to the earlier studies showed an elevated concentration of Pb, Be, Bi, Co, Cr, Ni, Sb, and Zn in hair and urine. These heavy metals were more elevated in mining than in smelting. Considering gender differences, females were likely to be more affected than male. By investigating age differences in this area, high heavy metal concentrations in male's hair and urine existed in age of 18-40 and ≥ 66, respectively. However, females did not present homogeneous age distribution. Hair and urine showed a different distribution of heavy metals in different age and gender. In some cases, significant correlation was found between heavy metals in hair and urine (P > 0.05 and P > 0.01) in mining area. The estimated average daily intake of heavy metals in vegetables showed a great contribution compared to the soil and water. Non-carcinogenic and carcinogenic risk values of total pathways in mining and smelting areas were higher than 1 and exceeded the acceptable levels. Thus, the obtained data might be useful for further studies. They can serve as a basis of comparison and assessing the effect of simultaneous exposure from heavy metals in mining and smelting areas, and potential health risks from exposure to heavy metals in vegetables need more consideration.

  19. Excited state distribution of reflected hydrogen atoms at metal surfaces - Development of theoretical models

    NASA Astrophysics Data System (ADS)

    Kato, D.; Kenmotsu, T.; Ohya, K.; Tanabe, T.

    2009-06-01

    Numerical methods were developed to study single electron capture by translating hydrogen atoms above metal surfaces. The present method gives predictions for hitherto unknown population distribution of excited species in hydrogen atoms reflected at the metal surfaces. The excited state abundance was calculated for Mo surface. Kinetic energy distribution of the reflected atoms was taken into account with the aid of the Monte-Carlo simulation code (ACAT). Energy distribution associated with the 3d 2 excited state in reflected neutrals consistently explains peak energy variation with incident energies of Doppler-shifted D α lines measured by Tanabe et al. Occupation probability of the magnetic sub-levels is obtained to be highly polarized. It suggests strong anisotropy in angular distribution of photon emission from the excited states created via the surface electron capture.

  20. Distribution transformers not subject to destructive failure: Phase 3, Design improvements and preliminary market analyses: Final report

    SciTech Connect

    Baranowski, J.F.; Goedde, G.L.

    1987-10-01

    This research project investigated the substitution of inorganic high temperature insulating materials for the oil/paper system in present transformer designs. A variety of designs for a transformer were studied and the processing techniques necessary to fabricate transformers were developed. Materials were found that could function successfully as turn-to-turn insulations and barrier insulations. But in order to utilize these materials effectively a pancake coil design had to be developed along with the necessary fabrication techniques. Twenty 25 kVA field test transformers were constructed and supplied to host utilities across the country. This report describes work to improve the transformer efficiency and to examine the feasibility of commercializing the non-destructive transformer technology. The initial market penetration would be limited to special utility and industrial market applications in competition with cast coil and open ventilated, dry-type transformers. This would involve larger kVA sizes and as a result, larger wide foil concentric designs were considered. It was expected that by building volume in this specialty market the cost of the inorganic materials would be reduced so that eventually this technology could compete in the distribution transformer market.

  1. Subcellular Distribution of Heavy Metals in Organs of Bivalve Modiolus Modiolus Living Along a Metal Contamination Gradient

    NASA Astrophysics Data System (ADS)

    Podgurskaya, Olga V.; Kavun, Victor Ya.

    2006-03-01

    Concentration and distribution of Fe, Zn, Cu, Cd, Mn, Pb, Ni among subcellular fractions (cellular membrane structures and cytosol) and Zn, Cu, Cd among cytoplasmic proteins in the kidney and digestive gland of mussel Modiolus modiolus living along a polymetallic concentration gradient were studied. It was found in the kidney of M. modiolus from contaminated sites that the Fe percent increased in the “membrane” fraction, whereas Zn, Pb, Ni and Mn percent increased in the cytosol compared to the kidney of the control mussel. Note kidney cytosol of M. modiolus from clean and contaminated sites sequestered major parts of Cu and Cd. In the digestive gland of M. modiolus from contaminated sites Fe, Zn, Cd, Mn, Ni percent increased in the “membrane” fraction, whereas Cu, Pb percent increased in the cytosol compared to digestive gland of control mussel. Gel-filtration chromatography shows kidney of M. modiolus contains increased metallothionein-like protein levels irrespective of ambient dissolved metal concentrations. It was shown that the metal detoxification system in the kidney and digestive gland of M. modiolus was efficient under extremely high ambient metal levels. However, under complex environmental contamination in the kidney of M. modiolus, the metal detoxification capacity of metallothionein-like proteins was damaged.

  2. No-reference peak signal to noise ratio estimation based on generalized Gaussian modeling of transform coefficient distributions

    NASA Astrophysics Data System (ADS)

    Ryu, Ji-Woo; Lee, Seon-Oh; Sim, Dong-Gyu; Han, Jong-Ki

    2012-02-01

    We present a no-reference peak signal to noise ratio (PSNR) estimation algorithm based on discrete cosine transform (DCT) coefficient distributions from H.264/MPEG-4 part 10 advanced video codec (H.264/AVC) bitstreams. To estimate the PSNR of a compressed picture without the original picture on the decoder side, it is important to model the distribution of transform coefficients obtained from quantized coefficients accurately. Whereas several conventional algorithms use the Laplacian or Cauchy distribution to model the DCT coefficient distribution, the proposed algorithm uses a generalized Gaussian distribution. Pearson's χ2 (chi-square) test was applied to show that the generalized Gaussian distribution is more appropriate than the other models for modeling the transform coefficients. The χ2 test was also used to find optimum parameters for the generalized Gaussian model. It was found that the generalized Gaussian model improves the accuracy of the DCT coefficient distribution, thus reducing the mean squared error between the real and the estimated PSNR.

  3. Distribution of platinum and other traffic related metals in sediments and clams (Corbicula sp.).

    PubMed

    Ruchter, Nadine; Sures, Bernd

    2015-03-01

    Platinum is part of traffic-emitted metals since the introduction of automotive catalyst converters. Still, automobile emissions are one of the major sources for metals in European river systems. However, field data on Pt is scarce and there is a lack of knowledge concerning the distribution and biological availability of Pt. Therefore, the distribution of traffic related metals (Cd, Cr, Cu, Ni, Pb, Pt, and Zn) was analyzed in sediment samples and in the Asian clam Corbicula sp. Samples were taken from three transects following road runoff inlets. Pt was introduced into the river by road runoff. The highest Pt concentrations in sediments were analyzed in the silt/clay fraction (45 ng/g), while the highest total Pt burden was obtained for the sand fraction, that makes up more than 60% of the sediment. Metal concentrations were related to the area of the drained street section as well as to their distance from the discharge point, and to grain size distribution within the sediment. Pt and other traffic related metals were accumulated by clams. Due to the feeding behavior of the freshwater mussel Corbicula sp. Pt concentrations in the soft tissue remain relatively low (max Pt concentration: 1.3 ng/g freeze dried soft tissue) and acute lethal or toxic effects therefore appear to be unlikely. Nonetheless, chronic exposure effects still have to be examined.

  4. Trace metals in the coals of the East Siberia: Distribution, utilization and environmental aspects

    SciTech Connect

    Pashkov, G.L.; Kuznetsov, P.N.; Kuzmin, V.I.; Boiko, Y.V.; Kontsevoi, A.A.

    1998-12-31

    Three coal basins in East Siberia, the Russia Lena, Kansk-Achinsk and South-Yakutsk basins, are huge coal basins which contain various sorts of both brown and high quality subbituminous and bituminous coals with low ash and sulfur content. The coals have great industrial significance for the production of energy, coke and chemicals. However, these coals are less characterized in terms of the content and distribution of trace metals, some of which are of industrial significance, other metals are toxic and radioactive. The data on the distribution of trace metals in these three coal basins, their geochemical occurrence and the behavior in chemical treatment and burning are presented in the paper. Separate coals were found to contain a large amount of valuable metals such as Ge (up to 1,400 g/ton of ash), V (up to 1,400 g/t), Sc (up to 220 g/t), Nb (up to 280 g/t), Cr (up to 1,300 g/t), Co (up to 320 g/t), Ni (580 g/t) and thus could be an industrial source of metal production. The methods for the extraction of Ge, Sc, Y, Nb and other metals prior or after combustion are described. The aspects of coal characterization in terms of toxic and radioactive impact on the environment are discussed.

  5. Cosmic distribution of highly ionized metals and their physical conditions in the EAGLE simulations

    NASA Astrophysics Data System (ADS)

    Rahmati, Alireza; Schaye, Joop; Crain, Robert A.; Oppenheimer, Benjamin D.; Schaller, Matthieu; Theuns, Tom

    2016-06-01

    We study the distribution and evolution of highly ionized intergalactic metals in the Evolution and Assembly of Galaxies and their Environment (EAGLE) cosmological, hydrodynamical simulations. EAGLE has been shown to reproduce a wide range of galaxy properties while its subgrid feedback was calibrated without considering gas properties. We compare the predictions for the column density distribution functions (CDDFs) and cosmic densities of Si IV, C IV, N V, O VI and Ne VIII absorbers with observations at redshift z = 0 to ˜6 and find reasonable agreement, although there are some differences. We show that the typical physical densities of the absorbing gas increase with column density and redshift, but decrease with the ionization energy of the absorbing ion. The typical metallicity increases with both column density and time. The fraction of collisionally ionized metal absorbers increases with time and ionization energy. While our results show little sensitivity to the presence or absence of AGN feedback, increasing/decreasing the efficiency of stellar feedback by a factor of 2 substantially decreases/increases the CDDFs and the cosmic densities of the metal ions. We show that the impact of the efficiency of stellar feedback on the CDDFs and cosmic densities is largely due to its effect on the metal production rate. However, the temperatures of the metal absorbers, particularly those of strong O VI, are directly sensitive to the strength of the feedback.

  6. Heavy metal distribution in an urban wetland impacted by combined sewer overflow.

    PubMed

    Rouff, Ashaki A; Eaton, Timothy T; Lanzirotti, Antonio

    2013-11-01

    The heavy metal content and distribution in an urban wetland affected by combined sewer overflow (CSO) discharge during dry conditions was evaluated. Metals identified in the CSO discharge were also measured upstream and downstream of the CSO. Metals were detected in the acid-extractable fraction of the wetland sediments and the roots of Phragmites australis plants. Sediment from the banks of a pool created by the CSO, and from a clay bed upstream were found to be moderately contaminated with Cu, Pb and Zn. Micro X-ray fluorescence (μ-XRF) of Phragmites roots from the CSO banks showed a correlation in the spatial distribution of Fe and Mn, attributed to the formation of mineral plaques on the root surface. Micro X-ray absorption near edge spectroscopy (μ-XANES) revealed that Cu and Zn were complexed with the organic ligands phytate and cysteine. The findings indicated that continuous discharge from the CSO is a source of heavy metals to the wetland. Metals bound to sediments are susceptible to remobilization and subsequent transport, whereas those associated with Phragmites roots may be more effectively sequestered. These observations provide insight into the behavior of heavy metals in urban areas where CSOs discharge into wetlands.

  7. Spatial distribution and multiple sources of heavy metals in the water of Chaohu Lake, Anhui, China.

    PubMed

    Li, Guolian; Liu, Guijian; Zhou, Chuncai; Chou, Chen-Lin; Zheng, Liugen; Wang, Jizhong

    2012-05-01

    In this study, a survey for the spatial distribution of heavy metals in Chaohu Lake of China was conducted. Sixty-two surface water samples were collected from entire lake including three of its main river entrances. This is the first systematic report concerning the content, distribution, and origin of heavy metals (Cu, Cr, Cd, Hg, Zn, and Ni) in the Chaohu Lake water. The results showed that heavy metals (Cu, Cr, Zn, and Ni) concentrations in the estuary of Nanfei River were relatively higher than those in the other areas, while content of Hg is higher in the southeast lake than northwest lake. Moreover, Cd has locally concentration in the surface water from the entire Chaohu Lake. The heavy metal average concentrations, except Hg, were lower than the cutoff values for the first-grade water quality (China Environment Quality Standard) which was set as the highest standard to protect the social nature reserves. The Hg content is between the grades three and four water quality, and other heavy metals contents are higher than background values. The aquatic environment of Chaohu Lake has apparently been contaminated. Both the cluster analysis (CA) and correlation analysis provide information about the origin of heavy metals in the Lake. Our findings indicated that agricultural activities and adjacent plants chimneys may contribute the most to Cd and Hg contamination of Chaohu Lake, respectively.

  8. Grain-size distribution and morphology of metal in E-chondrites

    NASA Astrophysics Data System (ADS)

    Easton, A. J.

    1983-03-01

    The size distribution and morphology of metal grains have been examined in 11 sections of types I and II E-chondrites. The changes in the grain-size distribution and morphology of metal grains correspond with the petrologic types and define a series that reflects increase in thermal metamorphism in the following order: type I, Kota Kota-Indarch-South Oman-St. Mark's; and type II, Jajh deh Kot Lalu-Atlanta-Daniel's Kuil-Hvittis-Pillistfer-Khairpur-Blithfield. Concentrations of metal grains adjacent to the perimeters of chondrules are observable throughout the sequence and delineate relic chondritic structure in six of the seven type II E-chondrites; relic structures are absent from Blithfield.

  9. Metals in sediment/pore water in Chaohu Lake: distribution, trends and flux.

    PubMed

    Wen, Shengfang; Shan, Baoqing; Zhang, Hong

    2012-01-01

    Nine metals, Cd, Cu, Ni, Pb, As, Cr, Zn, Fe, and Mn in sediment and pore water from 57 sampling sites in Chaohu Lake (Anhui Province, China) were analyzed for spatial distribution, temporal trends and diffuse flux in 2010. Metals in the surface sediment were generally the highest in the western lake center and Nanfei-Dianbu River estuary, with another higher area of As, Fe, and Mn occurring in the Qiyang River estuary. Metal contamination assessment using the New York sediment screening criteria showed that the sediment was severely contaminated in 44% of the area with Mn, 20% with Zn, 16% with Fe, 14% with As, and 6% with Cr and Ni. An increasing trend of toxic metals (Cd, Cu, Ni, Pb, As, Cr, Zn) and Mn with depth was shown in the western lake. Compared with metal content data from the sediment survey conducted in 1980s, the metal content of surface sediment in 2010 was 2.0 times that in the 1980s for Cr, Cu, Zn, and As in the western lake, and less than 1.5 times higher for most of the metals in the eastern lake. Among the metals, only Mn and As had a widespread positive diffuse flux from the pore water to overlying water across the whole lake. The estimated flux in the whole lake was on average 3.36 mg/(m2 x day) for Mn and 0.08 mg/(m2 x day) for As, which indicated a daily increase of 0.93 microg/L for Mn and 0.02 microg/L for As in surface water. The increasing concentration of metals in the sediment and the flux of metals from pore water to overlying water by diffusion and other physical processes should not be ignored for drinking-water sources.

  10. Predictive modeling of Time-Temperature-Transformation diagram of metallic glasses based on atomistically-informed classical nucleation theory.

    PubMed

    Sato, Yuji; Nakai, Chiaki; Wakeda, Masato; Ogata, Shigenobu

    2017-08-03

    Theoretical prediction of glass forming ability (GFA) of metallic alloys is a key process in exploring metallic alloy compositions with excellent GFA and thus with the ability to form a large-sized bulk metallic glass. Molecular dynamics (MD) simulation is a promising tool to achieve a theoretical prediction. However, direct MD prediction continues to be challenging due to the time-scale limitation of MD. With respect to practical bulk metallic glass alloys, the time necessary for quenching at a typical cooling rate is five or more orders of magnitude higher than that at the MD time-scale. To overcome the time-scale issue, this study proposes a combined method of classical nucleation theory and MD simulations. The method actually allows to depict the time-temperature-transformation (TTT) diagram of the bulk metallic glass alloys. The TTT directly provides a prediction of the critical cooling rate and GFA. Although the method assumes conventional classical nucleation theory, all the material parameters appearing in the theory were determined by MD simulations using realistic interatomic potentials. The method is used to compute the TTT diagrams and critical cooling rates of two Cu-Zr alloy compositions (Cu50Zr50 and Cu20Zr80). The results indicate that the proposed method reasonably predicts the critical cooling rate based on the computed TTT.

  11. Distribution of Heavy Metals in Soil of Urban Ecosystems by the Example of the Oryol City

    NASA Astrophysics Data System (ADS)

    Vorobyov, S.; Kozlov, D.; Poturaeva, T.; Chernyaeva, I.

    2017-05-01

    The article deals with the impact of vehicle emissions on the distribution of heavy metals in the soils of urban ecotopes - land urban areas with similar parameters of the biosphere, the technosphere, demographic and urban development factors by the example of the Oryol city.

  12. Occurrence and distribution of selected metals in streams near Huntsville, Alabama

    USGS Publications Warehouse

    German, E.R.; Knight, Alfred L.

    1973-01-01

    Arsenic, cadmium, chromium, cobalt, lead, mercury, and zinc are widely distributed around Huntsville, Ala. However, concentrations of these metals in streamflow in the vicinity of the Huntsville municipal water intake during June, August, and September 1971 did not exceed the limits recommended for a public drinking water supply. The occurrence of these metals in general is related to man's activities. Information gained during this study suggests that cadmium and the other metals are associated with and transported with suspended sediment, bed material, and airborne dust particles. Lead and zinc were the most abundant of the selected metals in streamflow, bed material, and rainwater samples. The highest concentration of cadmium was detected downstream from an industrial park in the Flint River basin; rainwater samples also contained a relatively high level of cadmium.

  13. Efficient representation of bidirectional reflectance distribution functions for metallic paints considering manufacturing parameters

    NASA Astrophysics Data System (ADS)

    Kook Seo, Myoung; Yeon Kim, Kang; Bong Kim, Duck; Lee, Kwan H.

    2011-01-01

    Metallic paint has been widely used to provide for special visual appearance to various products so that photorealistic rendering of this material has been an important issue in the development of new products. We introduce a new approach that predicts the reflectance of metallic paint while considering manufacturing parameters. Our main idea is to simulate the appearance of various metallic paints having different composition of constituent materials by combination of measured bidirectional reflectance distribution functions and thereby to find a paint that provides optimal appearance of a product with appropriate composition of constituent materials. We mainly focused on two paint parameters, average size and density of aluminum flakes, because they significantly affect the appearance of metallic paint. We also present a compact representation to approximate a large size of measured data using a few curve functions. We demonstrate the efficiency and usability of our reflectance estimation method using some examples.

  14. Distribution and fate of metals in the dispersion plume of a major municipal effluent.

    PubMed

    Gagnon, Christian; Saulnier, Isabelle

    2003-01-01

    The environmental impacts of municipal wastewater discharges on receiving waters are numerous and inputs of contaminants such as metals can cause toxicity to organisms in receiving waters. The effluents generated by the treatment plant of the city of Montreal, Canada, the largest such facility in the St. Lawrence Valley, was investigated to determine the environmental fate of trace metals in the receiving waters. Total and extractable metal concentrations were determined and physico-chemical parameters were measured to characterize the receiving waters and evaluate their influence on the fate and behaviour of metals released from the urban effluent. Our results showed that particulate metals near the effluent discharge point are highly reactive and their distribution seems to be significantly influenced by the abundance of HCl-reactive iron and manganese, which act as trace-metal carriers. The partitioning of metals between dissolved and particulate phases varies along the effluent dispersion plume and therefore could strongly influence the exposure routes for aquatic organisms that are exposed to the various contaminants released from the effluent.

  15. Distribution of metals between particulate and gaseous forms in a volcanic plume

    USGS Publications Warehouse

    Hinkley, T.K.

    1991-01-01

    In order to gain information on the distribution of metals between particles and gaseous forms in the plume of Kilauea volcano, a filter designed to collect metals associated with particles was followed in series by two other collectors intended to trap metals present in gaseous (atomic, molecular, or complexed) form: first an acid-bubbler bath and then a cold trap. Of the six metals measured, all of the In, Tl and Bi, and almost all of the Cd, Pb and Cu were found on the filter. None of any of the metals was detected in the acid-bubbler bath. Masses equivalent to 0.3% of the amount of Cd on the filter, 0.4% of the amount of Pb, and 9.3% of the Cu, were measured in the cold trap. The results indicate that all or nearly all of the six metals were partitioned to the particulate portion of the physical mixture of gases and particles that constitutes a volcanic plume, but that there may be systematic differences between chalcophile metals in the ways they are partitioned between particulate and gaseous phases in a cooled plume, and possibly differences in the acidity or other chemical properties of the molecular phases. ?? 1991 Springer-Verlag.

  16. Sediment-bound trace metals in Golfe-Juan Bay, northwestern Mediterranean: Distribution, availability and toxicity.

    PubMed

    Tiquio, Ma Gregoria Joanne; Hurel, Charlotte; Marmier, Nicolas; Taneez, Mehwish; Andral, Bruno; Jordan, Norbert; Francour, Patrice

    2017-05-15

    The concentration, potential mobility, cation exchange capacity and toxicity of eight sediment-bound metals in Golfe-Juan Bay, France were examined. Results revealed significant spatial gradient of metal contamination along Golfe-Juan coast. The distribution and concentration of the metals appear to be influenced by the geochemical properties of the sediment, proximity to anthropogenic sources and general water circulation in the bay. The portion of trace metals found in the exchangeable, carbonate, oxidizable and reducible fractions of the sediment constitute 31%-58% of the total sediment-bound trace metal content, suggesting significant potential for remobilization of metals into the water column. Pb and Ni content of the sediment exceed the limits of the French marine sediment quality. Whole sediment extracts showed acute toxicity to marine rotifers. This study concludes that monitoring and management of sediment-bound trace metals in Golfe-Juan Bay are important so as not to underestimate their availability and risk to the marine ecosystems. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Metal distribution in coral reef complex Cayo Arcas in the Gulf of Mexico.

    PubMed

    Cram, Silke; Ponce de León, Claudia A; Sommer, Irene; Miceli, Susi; Fernández, Pilar; Rivas, Hilda; Galicia, Leopoldo

    2009-04-01

    This study evaluated the spatial and temporal distribution of metals in the coral reef system Cayos Arcas and Triangulos in the Campeche Bank region, off the Yucatan peninsula in Mexico. No information has been generated before for the incorporation of natural and non-natural occurring metals, some of which are possibly endowed by the oil marine station Cayo Arcas. The multivariate exploratory study of the metals on the coral skeletons, showed the formation of two distinct groups. The metals that have the highest influence on the differentiation of the groups are the metals that are natural constituents of the coral skeletons, in particular Sr can explain much of the differences between the groups, and to a much lesser extent are the metals that could be indicators of pollution. This differentiation suggests that, in our case, the environment around the corals has a higher impact than the non-naturally occurring metals (and possible indicators of pollution). The two groups formed corresponded to: the coral cores influenced by open sea variables and the coral cores in the inner part of the keys which is less exposed to open sea variables. A chronological study was made to two samples that had the longest coral section and were situated in two clearly distinctive zones: an exposed surface subjected to high wave forces and another that was less exposed. Ni and Zn show an accumulation trend in both coral samples, while Ba showed an increase in incorporation around 1980 when the Cayo Arcas oil marine station was constructed.

  18. The metal abundance distribution of the oldest stellar component in the Sculptor dwarf spheroidal galaxy*

    NASA Astrophysics Data System (ADS)

    Clementini, G.; Ripepi, V.; Bragaglia, A.; Martinez Fiorenzano, A. F.; Held, E. V.; Gratton, R. G.

    2005-11-01

    Low-resolution spectroscopy obtained with FORS2 at the Very Large Telescope (VLT) has been used for the measurement of individual metal abundances ([Fe/H]) for 110 variable stars, including 107 RR Lyrae stars and one anomalous Cepheid, and to trace the metal distribution of the oldest stellar component in the Sculptor dwarf spheroidal galaxy. The RR Lyrae stars are spread over a 15 × 15 arcmin2 area around the galaxy centre. Their metallicities have an average value of [Fe/H]=-1.83 +/- 0.03 (rms = 0.26 dex) and cover the metallicity range -2.40 < [Fe/H] < -0.85 (on the scale of Zinn & West), but there is only one variable that has [Fe/H] > -1.3. The star-to-star scatter is larger than typical errors on individual metallicities (+/-0.15-0.16 dex), indicating a real spread in metal abundances. The radial velocities measured from the RR Lyrae spectra have a dispersion of 12.9kms-1. This value is consistent with the dispersion derived by Tolstoy et al. for metal-poor red giants associated with the blue horizontal branch stars in Sculptor. Along with the metallicity distribution these results suggest that most of the RR Lyrae stars in Sculptor arise from the same burst of stellar formation that produced the metal-poor component, originating the galaxy blue horizontal branch. The metal-rich red horizontal branch population found to be centrally concentrated only produced a few (if any) of the RR Lyrae stars in our sample. The spectroscopic metallicities were used along with the apparent luminosities to study the luminosity-metallicity relation followed by the RR Lyrae stars in Sculptor, for which we derive a shallow slope of 0.09magdex-1. This result can be due to a high level of evolution off the zero-age horizontal branch of the RR Lyrae stars in this galaxy, again in agreement with their origin from the blue horizontal branch population.

  19. Spatially distributed modeling of sediment and associated heavy metal transport on regional and catchment scale

    NASA Astrophysics Data System (ADS)

    Schindewolf, Marcus; Schmidt, Jürgen; Käpermann, Philipp

    2013-04-01

    Achievements of new legislations, as EU-Water Framework Directive (EU-WFD), require great efforts in order to reduce the yields of sediment and sediment attached heavy metals of surface water bodies. In this regard planning authorities strongly need comparable assessments on regional scale, which enables predictions on the level of measures. The study aims to identify the main sediment delivery areas in the German federal state of Saxony (18400 km²) and to locate pass over points of sediment and associated heavy metals into surface waters. Applying the process based EROSION 3D simulation model spatially distributed (20 m grid cell) estimates of sediment and particle attached heavy metal inputs are realized on regional and catchment scale related to three land use scenarios and a 10years rainfall event. Concerning these calculations it has to be considered, that this substances are predominantly attached to the fine-grained soil particles. The selective nature of soil erosion causes a preferentially transport of this fine particles while less contaminated larger particles remain on site. Consequently heavy metals are enriched in the eroded sediment compared to the origin soil. Hence it is essential that EROSION 3D provides the particle size distribution (clay, silt and sand) of transported sediments. Regarding heavy metal input calculations from sediment inputs, heavy metal contents of particle size classes has to be known. For this purpose particle size separates of erosion susceptible soils are analyzed. Comprehensive heavy metal contents of origin top soils are interpolated via kriging using available monitoring data. The regional scaled simulations identify the Saxon loess belt as the main affected region of sediment inputs. Since particle attached heavy metal transport to surface waters is strongly related to sediment delivery, the streams of this region suffer from considerable inputs. Compared to empirical estimates, the results of this study suggest that

  20. [Effects of Tillage on Distribution of Heavy Metals and Organic Matter Within Purple Paddy Soil Aggregates].

    PubMed

    Shi, Qiong-bin; Zhao, Xiu-lan; Chang, Tong-ju; Lu, Ji-wen

    2016-05-15

    A long-term experiment was utilized to study the effects of tillage methods on the contents and distribution characteristics of organic matter and heavy metals (Cu, Zn, Pb, Cd, Fe and Mn) in aggregates with different sizes (including 1-2, 0.25-1, 0.05-0.25 mm and < 0.05 mm) in a purple paddy soil under two tillage methods including flooded paddy field (FPF) and paddy-upland rotation (PR). The relationship between heavy metals and organic matter in soil aggregates was also analyzed. The results showed that the aggregates of two tillage methods were dominated by 0.05-0.25 mm and < 0.05 mm particle size, respectively. The contents of organic matter in each aggregate decreased with the decrease of aggregate sizes, however, compared to PR, FPF could significantly increase the contents of organic matter in soils and aggregates. The tillage methods did not significantly affect the contents of heavy metals in soils, but FPF could enhance the accumulation and distribution of aggregate, organic matter and heavy metals in aggregates with diameters of 1-2 mm and 0.25-1 mm. Correlation analysis found that there was a negative correlation between the contents of heavy metals and organic matter in soil aggregates, but a positive correlation between the amounts of heavy metal and organic matter accumulated in soil aggregates. From the slope of the correlation analysis equations, we could found that the sensitivities of heavy metals to the changes of soil organic matters followed the order of Mn > Zn > Pb > Cu > Fe > Cd under the same tillage. When it came to the same heavy metal, it was more sensitive in PR than in FPF.

  1. Sources, distribution, bioavailability, toxicity, and risk assessment of heavy metal(loid)s in complementary medicines.

    PubMed

    Bolan, Shiv; Kunhikrishnan, Anitha; Seshadri, Balaji; Choppala, Girish; Naidu, Ravi; Bolan, Nanthi S; Ok, Yong Sik; Zhang, Ming; Li, Chun-Guang; Li, Feng; Noller, Barry; Kirkham, Mary Beth

    2017-11-01

    The last few decades have seen the rise of alternative medical approaches including the use of herbal supplements, natural products, and traditional medicines, which are collectively known as 'Complementary medicines'. However, there are increasing concerns on the safety and health benefits of these medicines. One of the main hazards with the use of complementary medicines is the presence of heavy metal(loid)s such as arsenic (As), cadmium (Cd), lead (Pb), and mercury (Hg). This review deals with the characteristics of complementary medicines in terms of heavy metal(loid)s sources, distribution, bioavailability, toxicity, and human risk assessment. The heavy metal(loid)s in these medicines are derived from uptake by medicinal plants, cross-contamination during processing, and therapeutic input of metal(loid)s. This paper discusses the distribution of heavy metal(loid)s in these medicines, in terms of their nature, concentration, and speciation. The importance of determining bioavailability towards human health risk assessment was emphasized by the need to estimate daily intake of heavy metal(loid)s in complementary medicines. The review ends with selected case studies of heavy metal(loid) toxicity from complementary medicines with specific reference to As, Cd, Pb, and Hg. The future research opportunities mentioned in the conclusion of review will help researchers to explore new avenues, methodologies, and approaches to the issue of heavy metal(loid)s in complementary medicines, thereby generating new regulations and proposing fresh approach towards safe use of these medicines. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Regional distribution pattern of groundwater heavy metals resulting from agricultural activities

    NASA Astrophysics Data System (ADS)

    Nouri, J.; Mahvi, A. H.; Jahed, G. R.; Babaei, A. A.

    2008-09-01

    Contaminations of groundwater by heavy metals due to agricultural activities are growing recently. The objective of this study was to evaluate and map regional patterns of heavy metals (Cd, Zn and Cu) in groundwater on a plain with high agricultural activities. The study was conducted to investigate the concentration of heavy metals and distribution in groundwater in regions of Shush Danial and Andimeshk aquifers in the southern part of Iran. Presently, groundwater is the only appropriate and widely used source of drinking water for rural and urban communities in this region. The region covers an area of 1,100 km2 between the Dez and Karkhe rivers, which lead to the Persian Gulf. For this study, the region was divided into four sub-regions A, B, C and D. Additionally, 168 groundwater samples were collected from 42 water wells during the earlier months of 2004. The flame atomic absorption spectrometry (AAS-Flame) was used to measure the concentration of heavy metals in water samples and the Surfer software was used for determination of the contour map of metal distribution. The results demonstrated that in all of the samples, Cd and Zn concentrations were below the EPA MCLG and EPA secondary standard, respectively. However, the Cu contents of 4.8 % of all samples were higher than EPA MCL. It is also indicated that the concentrations of metals were more pronounced at the southern part of the studied region than at the others. The analysis of fertilizers applied for agricultural activities at this region also indicated that a great majority of the above-mentioned heavy metals were discharged into the environment. Absence of confining layers, proximity to land surface, excess agricultural activities in the southern part and groundwater flow direction that is generally from the north to the southern parts in this area make the southern region of the Shush plain especially vulnerable to pollution by heavy metals than by other contaminants.

  3. [Fraction distribution and risk assessment of heavy metals in stream sediments from a typical nonferrous metals mining city].

    PubMed

    Li, Ru-Zhong; Jiang, Yan-Min; Pan, Cheng-Rong; Chen, Jing; Xu, Jing-Jing

    2013-03-01

    A modified Tessier's sequential extraction procedure was used to investigate the fraction of seven types of heavy metals (Cd, Cr, Cu, Zn, Ni, Pb, As) in the surface sediments from Huixi Stream in Tongling City, a typical nonferrous metals mining city, China. Based on speciation distribution analysis of these metals, contamination degree and ecological risk assessment of heavy metals were conducted by means of risk assessment code (RAC) and mean sediment quality guideline quotient (SQG-Q). The results show that: (1) Cr and As are major composed with residual fractions, Zn, Ni and Pb are mainly constituted of residual and bound to iron and manganese oxides fractions, and Cu is dominated by bounding to organic matter, while Cd exists in approximate mass fractions of exchangeable, bound to carbonates, bound to iron and manganese oxides, and residue. (2) Carbonate and exchangeable mass fractions of Cd, Cr, Cu, Zn, Ni, Pb and As reach 46.48%, 4.62%, 4.05%, 4.12%, 9.17%, 0.97% and 0.03%, respectively. According to the RAC, Cd is of high risk to the environment, Cr, Cu, Zn and Ni are of low risk to the environment, while Pb and As pose extreme low risk to the environment. (3) The SQG index, calculated with SQG-Q, is 10.42, which is far higher than the threshold value 1.0, indicating that the sediment in Huixi Stream has a very high potential for biological toxicity effect. The PEL-Q indexes corresponding to Cd, Cr, Cu, Zn, Ni, Pb and As approach 4.23, 1.14, 20.75, 6.04, 2.33, 4.58 and 41.71, respectively, suggesting that all these metals have great potentials for biological toxicity and the adverse effects will frequently occur.

  4. Spontaneous, Solvent-Free, Polymer-Templated, Solid-Solid Transformation of Thin Metal Films into Nanoparticles.

    PubMed

    Hernández-Cruz, Olivia; Avila-Gutierrez, Lizeth; Zolotukhin, Mikhail G; Gonzalez, Gonzalo; Monroy, B Marel; Montiel, Raúl; Vera-Graziano, Ricardo; Romero-Ibarra, Josue E; Novelo-Peralta, Omar; Massó Rojas, Felipe Alonso

    2016-09-14

    Metal nanoparticles have unusual optical, electronic, sensing, recognition, catalytic, and therapeutic properties. They are expected to form the basis of many of the technological and biological innovations of this century. A prerequisite for future applications using nanoparticles as functional entities is control of the shape, size, and homogeneity of these nanoparticles and of their interparticle spacing and arrangement on surfaces, between electrodes, or in devices. Here, we demonstrate that thin films of gold, silver, and copper sputter-deposited onto the surface of an organic polymer poly[[1,1':4',1″-terphenyl]-4,4″-diyl(2-bromo-1-carboxyethylidene)] (PTBC) undergo spontaneous solid-solid transformation into nanoparticles. Furthermore, we show that, by varying the thickness of the films, the volume-to-surface ratio of the polymer substrate, and the amount of plasticizer, it is possible to control the rate of transformation and the morphology of the nanoparticles formed. PTBC containing Au nanoparticles was found to enhance the cell adhesion and proliferation. To the best of our knowledge, our findings constitute the first experimental evidence of spontaneous, room-temperature, solid-solid transformation of metal films sputtered onto the surface of an organic polymeric substrate into nanoparticles (crystals).

  5. Guest-Induced Two-Way Structural Transformation in a Layered Metal-Organic Framework Thin Film.

    PubMed

    Haraguchi, Tomoyuki; Otsubo, Kazuya; Sakata, Osami; Fujiwara, Akihiko; Kitagawa, Hiroshi

    2016-12-28

    Fabrication of thin films made of metal-organic frameworks (MOFs) has been intensively pursued for practical applications that use the structural response of MOFs. However, to date, only physisorption-induced structural response has been studied in these films. Chemisorption can be expected to provide a remarkable structural response because of the formation of bonds between guest molecules and reactive metal sites in host MOFs. Here, we report that chemisorption-induced two-way structural transformation in a nanometer-sized MOF thin film. We prepared a two-dimensional layered-type MOF Fe[Pt(CN)4] thin film using a step-by-step approach. Although the as-synthesized film showed poor crystallinity, the dehydrated form of this thin film had a highly oriented crystalline nature (Film-D) as confirmed by synchrotron X-ray diffraction (XRD). Surprisingly, under water and pyridine vapors, Film-D showed chemisorption-induced dynamic structural transformations to Fe(L)2[Pt(CN)4] thin films [L = H2O (Film-H), pyridine (Film-P)], where water and pyridine coordinated to the open Fe(2+) site. Dynamic structural transformations were also confirmed by in situ XRD, sorption measurement, and infrared reflection absorption spectroscopy. This is the first report of chemisorption-induced dynamic structural response in a MOF thin film, and it provides useful insights, which would lead to future practical applications of MOFs utilizing chemisorption-induced structural responses.

  6. Adaptive self-assembly and induced-fit transformations of anion-binding metal-organic macrocycles

    NASA Astrophysics Data System (ADS)

    Zhang, Ting; Zhou, Li-Peng; Guo, Xiao-Qing; Cai, Li-Xuan; Sun, Qing-Fu

    2017-06-01

    Container-molecules are attractive to chemists due to their unique structural characteristics comparable to enzymes and receptors in nature. We report here a family of artificial self-assembled macrocyclic containers that feature induced-fit transformations in response to different anionic guests. Five metal-organic macrocycles with empirical formula of MnL2n (M=Metal L=Ligand n=3, 4, 5, 6, 7) are selectively obtained starting from one simple benzimidazole-based ligand and square-planar palladium(II) ions, either by direct anion-adaptive self-assembly or induced-fit transformations. Hydrogen-bonding interactions between the inner surface of the macrocycles and the anionic guests dictate the shape and size of the product. A comprehensive induced-fit transformation map across all the MnL2n species is drawn, with a representative reconstitution process from Pd7L14 to Pd3L6 traced in detail, revealing a gradual ring-shrinking mechanism. We envisage that these macrocyclic molecules with adjustable well-defined hydrogen-bonding pockets will find wide applications in molecular sensing or catalysis.

  7. Energy Transform and Initial Acoustic Pressure Distribution in Microwave-induced Thermoacoustic Tomography.

    PubMed

    Yan, Jing; Tao, Chunjing; Wu, Shizeng

    2005-01-01

    A study of Microwave-induced Thermoacoustic Tomography is presented in this paper. Microwaves illuminate biological tissues to generate acoustic waves by thermoelastic expansion when electromagnetic energy was absorbed by human tissues. The generated acoustic waves carry information about different electromagnetic properties of different tissues which will be collected and processed to reconstruct human cross section image. In this paper, digital electromagnetic human body model with 1cm resolution was founded according to algorithm requirements. Firstly we analyzed the transform and interrelation among electromagnetic energy, heat energy and acoustic energy. On the basis of established human model: (1) we calculated initial acoustic pressure distribution in cross section image under plane microwave radiation with different frequency. It shows that microwave absorption properties and initial acoustic pressure were different with the change of frequency; (2) using single pulse to illuminate human model, initial acoustic pressure maps of thorax cross section at different time steps were analyzed. These results provided a research basis for further study and calculation of acoustic pressure in microwave-induced thermoacoustic tomography.

  8. In Situ Transformation of MOFs into Layered Double Hydroxide Embedded Metal Sulfides for Improved Electrocatalytic and Supercapacitive Performance.

    PubMed

    Yilmaz, Gamze; Yam, Kah Meng; Zhang, Chun; Fan, Hong Jin; Ho, Ghim Wei

    2017-07-01

    Direct adoption of metal-organic frameworks (MOFs) as electrode materials shows impoverished electrochemical performance owing to low electrical conductivity and poor chemical stability. In this study, we demonstrate self-templated pseudomorphic transformation of MOF into surface chemistry rich hollow framework that delivers highly reactive, durable, and universal electrochemically active energy conversion and storage functionalities. In situ pseudomorphic transformation of MOF-derived hollow rhombic dodecahedron template and sulfurization of nickel cobalt layered double hydroxides (NiCo-LDHs) lead to the construction of interlayered metal sulfides (NiCo-LDH/Co9 S8 ) system. The embedment of metal sulfide species (Co9 S8 ) at the LDH intergalleries offers optimal interfacing of the hybrid constituent elements and materials stability. The hybrid NiCo-LDH/Co9 S8 system collectively presents an ideal porous structure, rich redox chemistry, and high electrical conductivity matrix. This leads to a significant enhancement in its complementary electrocatalytic hydrogen evolution and supercapacitive energy storage properties. This work establishes the potential of MOF derived scaffold for designing of novel class hybrid inorganic-organic functional materials for electrochemical applications and beyond. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. SIZE DISTRIBUTION AND RATE OF PRODUCTION OF AIRBORNE PARTICULATE MATTER GENERATED DURING METAL CUTTING

    SciTech Connect

    M.A. Ebadian, Ph.D.; S.K. Dua, Ph.D., C.H.P.; Hillol Guha, Ph.D.

    2001-01-01

    During deactivation and decommissioning activities, thermal cutting tools, such as plasma torch, laser, and gasoline torch, are used to cut metals. These activities generate fumes, smoke and particulates. These airborne species of matter, called aerosols, may be inhaled if suitable respiratory protection is not used. Inhalation of the airborne metallic aerosols has been reported to cause ill health effects, such as acute respiratory syndrome and chromosome damage in lymphocytes. In the nuclear industry, metals may be contaminated with radioactive materials. Cutting these metals, as in size reduction of gloveboxes and tanks, produces high concentrations of airborne transuranic particles. Particles of the respirable size range (size < 10 {micro}m) deposit in various compartments of the respiratory tract, the fraction and the site in the respiratory tract depending on the size of the particles. The dose delivered to the respiratory tract depends on the size distribution of the airborne particulates (aerosols) and their concentration and radioactivity/toxicity. The concentration of airborne particulate matter in an environment is dependent upon the rate of their production and the ventilation rate. Thus, measuring aerosol size distribution and generation rate is important for (1) the assessment of inhalation exposures of workers, (2) the selection of respiratory protection equipment, and (3) the design of appropriate filtration systems. Size distribution of the aerosols generated during cutting of different metals by plasma torch was measured. Cutting rates of different metals, rate of generation of respirable mass, as well as the fraction of the released kerf that become respirable were determined. This report presents results of these studies. Measurements of the particles generated during cutting of metal plates with a plasma arc torch revealed the presence of particles with mass median aerodynamic diameters of particles close to 0.2 {micro}m, arising from

  10. Speciation and transformation of heavy metals during vermicomposting of animal manure.

    PubMed

    Lv, Baoyi; Xing, Meiyan; Yang, Jian

    2016-06-01

    This work was conducted to evaluate the effects of vermicomposting on the speciation and mobility of heavy metals (Zn, Pb, Cr, and Cu) in cattle dung (CD) and pig manure (PM) using tessier sequential extraction method. Results showed that the pH, total organic carbon and C/N ratio were reduced, while the electric conductivity and humic acid increased after 90days vermicomposting. Moreover, the addition of earthworm could accelerate organic stabilization in vermicomposting. The total heavy metals in final vermicompost from CD and PM were higher than the initial values and the control without worms. Sequential extraction indicated that vermicomposting decreased the migration and availability of heavy metals, and the earthworm could reduce the mobile fraction, while increase the stable fraction of heavy metals. Furthermore, these results indicated that vermicomposting played a positive role in stabilizing heavy metals in the treatment of animal manure. Copyright © 2016 Elsevier Ltd. All rights reserved.

  11. Metal-Organic Nanosheets Formed via Defect-Mediated Transformation of a Hafnium Metal-Organic Framework.

    PubMed

    Cliffe, Matthew J; Castillo-Martínez, Elizabeth; Wu, Yue; Lee, Jeongjae; Forse, Alexander C; Firth, Francesca C N; Moghadam, Peyman Z; Fairen-Jimenez, David; Gaultois, Michael W; Hill, Joshua A; Magdysyuk, Oxana V; Slater, Ben; Goodwin, Andrew L; Grey, Clare P

    2017-04-19

    We report a hafnium-containing MOF, hcp UiO-67(Hf), which is a ligand-deficient layered analogue of the face-centered cubic fcu UiO-67(Hf). hcp UiO-67 accommodates its lower ligand:metal ratio compared to fcu UiO-67 through a new structural mechanism: the formation of a condensed "double cluster" (Hf12O8(OH)14), analogous to the condensation of coordination polyhedra in oxide frameworks. In oxide frameworks, variable stoichiometry can lead to more complex defect structures, e.g., crystallographic shear planes or modules with differing compositions, which can be the source of further chemical reactivity; likewise, the layered hcp UiO-67 can react further to reversibly form a two-dimensional metal-organic framework, hxl UiO-67. Both three-dimensional hcp UiO-67 and two-dimensional hxl UiO-67 can be delaminated to form metal-organic nanosheets. Delamination of hcp UiO-67 occurs through the cleavage of strong hafnium-carboxylate bonds and is effected under mild conditions, suggesting that defect-ordered MOFs could be a productive route to porous two-dimensional materials.

  12. Kinetics of transformation in an in-situ aluminum-strontium deformation processed metal-metal composite

    NASA Astrophysics Data System (ADS)

    Frerichs, Andrew Elliott

    2011-12-01

    Efficient electricity transmission is a key component in all plans to increase the amount of renewable power used in the decades ahead. Prime solar and wind generation sites are usually distant from major population centers, resulting in the need for improved conductor wires that are stronger, lighter, and have better conductivity than conventional conductors. Deformation processed metal-metal composites (DMMCs) have a desirable combination of high strength and good conductivity. One such DMMC, aluminum-strontium, was investigated in this study. The composite wire was created by extrusion, swaging, and wire drawing of bundled Al and Sr wires. Intermetallic compound formation between Al and Sr is of particular interest to produce a strong, conductive wire with good high-temperature strength. Samples of swaged and drawn Al-Sr composite wire were heat treated at 483K, 513K, 543K and 573K to produce samples at varying stages of intermetallic compound formation. Resistivity measurements were taken from samples over a range of heat treatment times and temperatures to calculate the activation energy for Al-Sr intermetallic compound formation. Scanning electron microscopy, differential scanning calorimetry, and x-ray diffraction were used to investigate the changes in the microstructure occurring in the samples as a function of heat treatment. In addition, mechanical properties data were generated for pure Sr metal.

  13. Synthesis and transformations of alkylphosphate and alkoxysiloxide metal complexes to multicomponent oxide materials

    NASA Astrophysics Data System (ADS)

    Lugmair, Claus Guenter

    This thesis describes the synthesis of mixed element oxide materials utilizing oxygen rich ``single-source precursor'' molecules. The key attributes of these precursor complexes are that they possess the stoichiometry of the targeted oxide material and that they can be converted to carbon free materials by mild thermal treatment. Complexes of Al, Cu, Fe, Hf, Nb, Ta, Ti, and Zr were prepared that contain tris(tert-butoxy)siloxy ligands as precursors to silica based materials. The pyrolytic decomposition of these complexes occur under mild conditions, with onset temperatures to decomposition between 95 and 200sp°C. The resulting metal-silica or metal oxide-silica materials contain very little carbon. The solid state transformation of Zrlbrack OSi(OsptBu)sb3rbracksb4 to ZrOsb2{*}4SiOsb2 produced an open fibrous material with pores which are ca. 20 nm in diameter. The solution phase thermolysis of the various metal siloxide complexes in anhydrous organic solvents led to xerogels consisting of small spherical primary particles (≤ca. 5 nm). These xerogels typically possess very high surface areas. The ZrOsb2{*}4SiOsb2 materials are amorphous as initially formed, and subsequent crystallizations of tetragonal ZrOsb2, monoclinic ZrOsb2, and cristobalite occur at relatively high temperatures. The enhanced stabilization of the amorphous and tetragonal phases of zirconia, relative to those derived from many sol-gel systems, implies that these single-source precursors initially produce highly homogeneous materials and that subsequent crystallizations are to a large degree diffusion-controlled, Careful addition of 1 or 2 equiv of water to THF solutions of Mlbrack OSi(OsptBu)sb3rbracksb4 (M = Zr, Hf) produced the isolable aqua complexes Mlbrack OSi(OsptBu)sb3rbracksb4(Hsb2O) and Mlbrack OSi(OsptBu)sb3rbracksb4(Hsb2O)sb2. It is likely that the hydrolysis of Zrlbrack OSi(OsptBu)sb3rbracksb4(Hsb2O)sb2 also occurs by an associative mechanism via the tris(aqua) intermediate

  14. In Situ TEM Nanoindentation Studies on Stress-Induced Phase Transformations in Metallic Materials

    NASA Astrophysics Data System (ADS)

    Liu, Y.; Wang, H.; Zhang, X.

    2016-01-01

    Although abundant phase transformations are in general thermally driven processes, there are many examples wherein stresses can induce phase transformations. Numerous in situ techniques, such as in situ x-ray diffraction and neutron diffraction, have been applied to reveal phase transformations. Recently, an in situ nanoindentation technique coupled with transmission electron microscopy demonstrated the capability to directly correlating stresses with phase transformations and microstructural evolutions at a submicron length scale. Here we briefly review in situ studies on stress-induced diffusional and diffusionless phase transformations in amorphous CuZrAl alloy and NiFeGa shape memory alloy. In the amorphous CuZrAl, in situ nanoindentation studies show that the nucleation of nanocrystals (a diffusional process) occurs at ultra-low stresses manifested by a prominent stress drop. In the NiFeGa shape memory alloy, two distinctive types of martensitic (diffusionless) phase transformations accompanied by stress plateaus are observed, including a reversible gradual phase transformation at low stress levels, and an irreversible abrupt phase transition at higher stress levels.

  15. In Situ TEM Nanoindentation Studies on Stress-Induced Phase Transformations in Metallic Materials

    SciTech Connect

    Liu, Y.; Wang, H.; Zhang, X.

    2015-11-30

    Though abundant phase transformations are in general thermally driven processes, there are many examples wherein stresses can induce phase transformations. We applied numerous in situ techniques, such as in situ x-ray diffraction and neutron diffraction in order to reveal phase transformations. Recently, an in situ nanoindentation technique coupled with transmission electron microscopy demonstrated the capability to directly correlating stresses with phase transformations and microstructural evolutions at a submicron length scale. We briefly review in situ studies on stress-induced diffusional and diffusionless phase transformations in amorphous CuZrAl alloy and NiFeGa shape memory alloy. Moreover, in the amorphous CuZrAl, in situ nanoindentation studies show that the nucleation of nanocrystals (a diffusional process) occurs at ultra-low stresses manifested by a prominent stress drop. In the NiFeGa shape memory alloy, two distinctive types of martensitic (diffusionless) phase transformations accompanied by stress plateaus are observed, including a reversible gradual phase transformation at low stress levels, and an irreversible abrupt phase transition at higher stress levels.

  16. In Situ TEM Nanoindentation Studies on Stress-Induced Phase Transformations in Metallic Materials

    DOE PAGES

    Liu, Y.; Wang, H.; Zhang, X.

    2015-11-30

    Though abundant phase transformations are in general thermally driven processes, there are many examples wherein stresses can induce phase transformations. We applied numerous in situ techniques, such as in situ x-ray diffraction and neutron diffraction in order to reveal phase transformations. Recently, an in situ nanoindentation technique coupled with transmission electron microscopy demonstrated the capability to directly correlating stresses with phase transformations and microstructural evolutions at a submicron length scale. We briefly review in situ studies on stress-induced diffusional and diffusionless phase transformations in amorphous CuZrAl alloy and NiFeGa shape memory alloy. Moreover, in the amorphous CuZrAl, in situ nanoindentationmore » studies show that the nucleation of nanocrystals (a diffusional process) occurs at ultra-low stresses manifested by a prominent stress drop. In the NiFeGa shape memory alloy, two distinctive types of martensitic (diffusionless) phase transformations accompanied by stress plateaus are observed, including a reversible gradual phase transformation at low stress levels, and an irreversible abrupt phase transition at higher stress levels.« less

  17. [Distribution and migration of heavy metals in soil profiles by high-resolution sampling].

    PubMed

    Ruan, Xin-ling; Zhang, Gan-lin; Zhao, Yu-guo; Yuan, Da-gang; Wu, Yun-jin

    2006-05-01

    The vertical distribution of heavy metals in soils profiles is a result of heavy metals accumulation and migration under combining influence of edaphic factors and environmental conditions. It's an important basis for evaluation of heavy metals pollution and remediation of contaminated soils. By traditional sampling methods, i.e., soils were sampled according to pedogenetic horizons, only very general information about element migration can be learned. In the current study, three sites near a steel factory were selected to represent three types of land use, i.e. forest, dry land for vegetable cultivation and rice paddy field. Soils were sampled horizontally by high-resolution sampling method. In the top of 40 cm soils were sectioned in 2 cm intervals, then 5 cm intervals in next 40 cm, and 10 cm intervals in the last 20 cm of profile. Total content of Cu, Zn, Pb, Cr and Cd were determined, and the vertical distribution of Cu, Zn, Pb, Cr, Cd in every profile was analyzed. The results indicated that enrichment of heavy metals appeared in the upper most layer of the natural forest soil that without any anthropic disturbance, and this phenomenon proved that heavy metals were coming from atmospheric deposition. We found that Cu, Zn and Pb moved downward in a short distance, Cd migrated relatively faster than Cu, Zn and Pb, while Cr had no recognizable location of migration front. In the soil profiles of dry land and paddy field, there were influences of agricultural practice, the distribution and movement of metals were thus different form those of the forest soil. In cultivated layer heavy metals were evenly distributed because soils in the upper layer were mixed by cultivation, however, bellow the cultivated layer obvious migration took place again. It is concluded that different heavy metals have different mobility and there is such a relative order: Cd>Cu>Zn>Pb. The study shows that the distribution pattern can be obtained with the currently adopted high

  18. Phase functions, glories, fogbows and coronas for clouds with mirror-transformed gamma- and bimodal-distributions

    NASA Astrophysics Data System (ADS)

    Kablukova, Evgeniya G.; Prigarin, Sergei M.; Rozhenko, Sergei A.

    2015-11-01

    In this paper we study the phase functions for water-droplet clouds and fogs computed by the Mie theory for specific bimodal and "mirror"- transformed droplet size gamma-distributions. In addition, we construct images of coronas, fogbows and glory that can occur for such cloud and fog models.

  19. Evolution of heavy quark distribution function on quark-gluon plasma: Using the Iterative Laplace Transform Method

    NASA Astrophysics Data System (ADS)

    Mehrabi Pari, Sharareh; Javidan, Kurosh; Taghavi Shahri, Fatemeh

    2016-05-01

    The "Laplace Transform Method" is used to solve the Fokker-Plank equation for finding the time evolution of the heavy quarks distribution functions such as charm and bottom in quark gluon plasma. These solutions will lead us to calculation of nuclear suppression factor RAA. The results have good agreement with available experiment data from the PHENIX collaboration.

  20. Effect of sulfate on the transformation of corrosion scale composition and bacterial community in cast iron water distribution pipes

    EPA Science Inventory

    The stability of iron corrosion products and the bacterial composition of biofilm in drinking water distribution systems (DWDS) could have great impact on the water safety at the consumer ends. In this work, pipe loops were setup to investigate the transformation characteristics ...

  1. 10 CFR Appendix A to Subpart K of... - Uniform Test Method for Measuring the Energy Consumption of Distribution Transformers

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... CONSERVATION ENERGY EFFICIENCY PROGRAM FOR CERTAIN COMMERCIAL AND INDUSTRIAL EQUIPMENT Distribution... Loading Level Adjustment. If the output loading level for energy efficiency is different from the level at... energy efficiency load level, Plc2 is as calculated in section 4.5.3.3, Por is the rated transformer...

  2. Effect of sulfate on the transformation of corrosion scale composition and bacterial community in cast iron water distribution pipes

    EPA Science Inventory

    The stability of iron corrosion products and the bacterial composition of biofilm in drinking water distribution systems (DWDS) could have great impact on the water safety at the consumer ends. In this work, pipe loops were setup to investigate the transformation characteristics ...

  3. Determination of grain size distribution function using two-dimensional Fourier transforms of tone pulse encoded images

    NASA Technical Reports Server (NTRS)

    Generazio, E. R.

    1986-01-01

    Microstructural images may be tone pulse encoded and subsequently Fourier transformed to determine the two-dimensional density of frequency components. A theory is developed relating the density of frequency components to the density of length components. The density of length components corresponds directly to the actual grain size distribution function from which the mean grain shape, size, and orientation can be obtained.

  4. [Migration and transformation of heavy metals in street dusts with different particle sizes during urban runoff].

    PubMed

    He, Xiao-Yan; Zhao, Hong-Tao; Li, Xu-Yong; Lian, Bin; Wang, Xiao-Mei

    2012-03-01

    The heavy metal pollution in runoff caused by street dust washoff has been an increasingly prominent problem in the context of rapid urbanization in China. Based on measurement of heavy metal contents in street dusts with different particle sizes and an experiment of street dust washoff using simulated rainfall, we analyzed the role of particle size of street dust in heavy metal pollution, and the variation in geometrical forms of heavy metals during street dust washoff. Our results showed that the heavy metal concentration decreased from "static" street dust to "dynamic" runoff particulate in the same diameter particles. Heavy metals in street dust were dissolved and extracted during washoff. The average loss proportion of the five metals (Cr, Cu, Ni, Pb, Zn) were 24.3%, 56.8%, 34.3%, 22.8%, 27.3%, respectively. The loss proportion increased with the decrease of the particle size of street dust. Proportion of extracted form dust was higher in street than that in washoff samples, which suggested some dissolved loss in water. In washoff samples, dissolved metals of waterphase did not have significant changes; however, heavy metals with particle state in waterphase reduced rapidly during runoff. Meanwhile, heavy metals of solid-phase particle reduced during runoff. Street dust with small particle size had higher loss rate during runoff. The variation rate of street dust loss among different particle sizes varied from 4.6% to 62.1%. Street dust with smaller particle size had higher migration ability in runoff, which was more risky to urban water pollution.

  5. Determination of the size distribution of metallic nanoparticles by optical extinction spectroscopy

    SciTech Connect

    Pena, Ovidio; Rodriguez-Fernandez, Luis; Rodriguez-Iglesias, Vladimir; Kellermann, Guinther; Crespo-Sosa, Alejandro; Cheang-Wong, Juan Carlos; Silva-Pereyra, Hector Gabriel; Arenas-Alatorre, Jesus; Oliver, Alicia

    2009-01-20

    A method is proposed to estimate the size distribution of nearly spherical metallic nanoparticles (NPs) from optical extinction spectroscopy (OES) measurements based on Mie's theory and an optimization algorithm. The described method is compared against two of the most widely used techniques for the task: transmission electron microscopy (TEM) and small-angle x-ray scattering (SAXS). The size distribution of Au and Cu NPs, obtained by ion implantation in silica and a subsequent thermal annealing in air, was determined by TEM, grazing-incidence SAXS (GISAXS) geometry, and our method, and the average radius obtained by all the three techniques was almost the same for the two studied metals. Concerning the radius dispersion (RD), OES and GISAXS give very similar results, while TEM considerably underestimates the RD of the distribution.

  6. The Halo Stars in NGC 5128. III. An Inner Halo Field and the Metallicity Distribution

    NASA Astrophysics Data System (ADS)

    Harris, William E.; Harris, Gretchen L. H.

    2002-06-01

    We present new Hubble Space Telescope WFPC2 (V,I) photometry for field stars in NGC 5128 at a projected distance of 8 kpc from the galaxy center, which probes a mixture of its inner halo and outer bulge. The color-magnitude diagram shows an old red giant branch that is even broader in color than our two previously studied outer halo fields (at 21 and 31 kpc), with significant numbers of stars extending to solar metallicity and higher. The peak frequency of the metallicity distribution function (MDF) is at [m/H]~=-0.4, with even fewer metal-poor stars than in the outer halo fields. If we use the 21 and 31 kpc fields to define template ``halo'' MDFs and subtract these from the 8 kpc field, the residual ``bulge'' population has a mean [m/H]~=-0.2, similar to the bulges of other large spiral and elliptical galaxies. We find that the main features of the halo MDF can be reproduced by a simple chemical evolution model in which early star formation goes on simultaneously with an initial stage of rapid infall of very metal-poor gas, after which the infall dies away exponentially. Finally, by comparison with the MDFs for the NGC 5128 globular clusters, we find that in all the halo fields we have studied there is a clear decrease of specific frequency SN (number of clusters per unit halo light) with increasing metallicity. At the lowest-metallicity range ([Fe/H]<-1.6) SN is ~4-8, while at metallicities [Fe/H]>-1 it has dropped to ~=1.5. This trend may indicate that globular cluster formation efficiency is a strong function of the metallicity of the protocluster gas. However, we suggest an alternate possibility, which is that globular clusters form preferentially sooner than field stars. If most of the cluster formation within a host giant molecular cloud takes place sooner than most of the distributed field-star formation and if the earliest most metal-poor star-forming clouds are prematurely disrupted by their own first bursts of star formation, then they would leave

  7. Efficient implementation of a multidimensional fast fourier transform on a distributed-memory parallel multi-node computer

    DOEpatents

    Bhanot, Gyan V.; Chen, Dong; Gara, Alan G.; Giampapa, Mark E.; Heidelberger, Philip; Steinmacher-Burow, Burkhard D.; Vranas, Pavlos M.

    2008-01-01

    The present in invention is directed to a method, system and program storage device for efficiently implementing a multidimensional Fast Fourier Transform (FFT) of a multidimensional array comprising a plurality of elements initially distributed in a multi-node computer system comprising a plurality of nodes in communication over a network, comprising: distributing the plurality of elements of the array in a first dimension across the plurality of nodes of the computer system over the network to facilitate a first one-dimensional FFT; performing the first one-dimensional FFT on the elements of the array distributed at each node in the first dimension; re-distributing the one-dimensional FFT-transformed elements at each node in a second dimension via "all-to-all" distribution in random order across other nodes of the computer system over the network; and performing a second one-dimensional FFT on elements of the array re-distributed at each node in the second dimension, wherein the random order facilitates efficient utilization of the network thereby efficiently implementing the multidimensional FFT. The "all-to-all" re-distribution of array elements is further efficiently implemented in applications other than the multidimensional FFT on the distributed-memory parallel supercomputer.

  8. Efficient implementation of multidimensional fast fourier transform on a distributed-memory parallel multi-node computer

    DOEpatents

    Bhanot, Gyan V [Princeton, NJ; Chen, Dong [Croton-On-Hudson, NY; Gara, Alan G [Mount Kisco, NY; Giampapa, Mark E [Irvington, NY; Heidelberger, Philip [Cortlandt Manor, NY; Steinmacher-Burow, Burkhard D [Mount Kisco, NY; Vranas, Pavlos M [Bedford Hills, NY

    2012-01-10

    The present in invention is directed to a method, system and program storage device for efficiently implementing a multidimensional Fast Fourier Transform (FFT) of a multidimensional array comprising a plurality of elements initially distributed in a multi-node computer system comprising a plurality of nodes in communication over a network, comprising: distributing the plurality of elements of the array in a first dimension across the plurality of nodes of the computer system over the network to facilitate a first one-dimensional FFT; performing the first one-dimensional FFT on the elements of the array distributed at each node in the first dimension; re-distributing the one-dimensional FFT-transformed elements at each node in a second dimension via "all-to-all" distribution in random order across other nodes of the computer system over the network; and performing a second one-dimensional FFT on elements of the array re-distributed at each node in the second dimension, wherein the random order facilitates efficient utilization of the network thereby efficiently implementing the multidimensional FFT. The "all-to-all" re-distribution of array elements is further efficiently implemented in applications other than the multidimensional FFT on the distributed-memory parallel supercomputer.

  9. Ion activity and distribution of heavy metals in acid mine drainage polluted subtropical soils.

    PubMed

    Li, Yong-Tao; Becquer, Thierry; Dai, Jun; Quantin, Cécile; Benedetti, Marc F

    2009-04-01

    The oxidative dissolution of mine wastes gives rise to acidic, metal-enriched mine drainage (AMD) and has typically posed an additional risk to the environment. The poly-metallic mine Dabaoshan in South China is an excellent test site to understand the processes affecting the surrounding polluted agricultural fields. Our objectives were firstly to investigate metal ion activity in soil solution, distribution in solid constituents, and spatial distribution in samples, secondly to determine dominant environment factors controlling metal activity in the long-term AMD-polluted subtropical soils. Soil Column Donnan Membrane Technology (SC-DMT) combined with sequential extraction shows that unusually large proportion of the metal ions are present as free ion in the soil solutions. The narrow range of low pH values prevents any pH effects during the binding onto oxides or organic matter. The differences in speciation of the soil solutions may explain the different soil degradation observed between paddy and non-paddy soils.

  10. Distribution, sources and ecological risk assessment of heavy metals in surface sediments from Lake Taihu, China

    NASA Astrophysics Data System (ADS)

    Yin, Hongbin; Gao, Yongnian; Fan, Chengxin

    2011-10-01

    The distribution, sources and ecological risk of heavy metals in surface sediments from Lake Taihu were studied. Results showed that the measured heavy metals had varied spatial distribution patterns, indicating that they had complex origins and controlling factors. Pearson's correlation analysis revealed that the total phosphorus and the loss on ignition were positively correlated with the measured metals except Cd. Principal component analysis and cluster analysis demonstrated that Hg, Cu, Cr, Cd and Pb might originate from domestic sewage and industrial wastewater, whereas As predominantly originated from natural processes. Potential ecological risk indices indicated that sediment from Wuli Lake, Gonghu Bay and the Northwest Area suffered high pollution, whereas other areas of Lake Taihu were moderately polluted. A comparison of metal levels with the effects range low (ERL) and effects range median (ERM) showed that metals exceeded their corresponding ERL limit at 13.6-72.3% (72.3% for As, 52.4% for Pb, 27.7% for Cu, 22.8% for Cd, 16.0 for Hg and 13.6% for Cr) of the sites investigated. Moreover, 3.90% and 0.50% of the sites sampled exceeded the ERM thresholds for Hg and Pb, respectively.

  11. Size distribution of heavy metal aerosols in cooling and spray dryer system

    SciTech Connect

    Wey, M.Y.; Yang, J.T.; Peng, C.Y.; Chiang, B.C.

    1999-11-01

    The cooling process prior to treating flue gas and the spray dryer process that removes acid components in flue gas are believed to influence the mass and elemental size distributions of heavy metal in fly ash. The main objective of this study was to investigate the effects of operating parameters on the mass and elemental size distributions of heavy metals in fly ash produced from a fluidized bed incineration and a water cooling or spray dryer flue gas treatment system. The operating parameters investigated included (1) the controlling temperature in the gas cooling system; (2) the controlling temperature in the spray dryer system; (3) the addition of organic chlorides; and (4) the addition of inorganic chloride. The experimental results indicated that the water cooling process and spray dryer process increase the amount of coarse fly ash and increase the total concentration of metal in fly ash. The amounts of fine fly ash and the total concentration of metal in fine fly ash increase with decreasing temperature during the water cooling process. However, the amounts of fine fly ash and the total concentration of metal in fine fly ash decrease with decreasing temperature during the spray dryer process.

  12. Spatial Distribution, Sources Apportionment and Health Risk of Metals in Topsoil in Beijing, China

    PubMed Central

    Sun, Chunyuan; Zhao, Wenji; Zhang, Qianzhong; Yu, Xue; Zheng, Xiaoxia; Zhao, Jiayin; Lv, Ming

    2016-01-01

    In order to acquire the pollution feature and regularities of distribution of metals in the topsoil within the sixth ring road in Beijing, a total of 46 soil samples were collected, and the concentrations of twelve elements (Nickel, Ni, Lithium, Li, Vanadium, V, Cobalt, Co, Barium, Ba, Strontium, Sr, Chrome, Cr, Molybdenum, Mo, Copper, Cu, Cadmium, Cd, Zinc, Zn, Lead, Pb) were analyzed. Geostatistics and multivariate statistics were conducted to identify spatial distribution characteristics and sources. In addition, the health risk of the analyzed heavy metals to humans (adult) was evaluated by an U.S. Environmental Protection Agency health risk assessment model. The results indicate that these metals have notable variation in spatial scale. The concentration of Cr was high in the west and low in the east, while that of Mo was high in the north and low in the south. High concentrations of Cu, Cd, Zn, and Pb were found in the central part of the city. The average enrichment degree of Cd is 5.94, reaching the standard of significant enrichment. The accumulation of Cr, Mo, Cu, Cd, Zn, and Pb is influenced by anthropogenic activity, including vehicle exhaustion, coal burning, and industrial processes. Health risk assessment shows that both non-carcinogenic and carcinogenic risks of selected heavy metals are within the safety standard and the rank of the carcinogenic risk of the four heavy metals is Cr > Co > Ni > Cd. PMID:27447657

  13. A uniform metal distribution in the intergalactic medium of the Perseus cluster of galaxies.

    PubMed

    Werner, Norbert; Urban, Ondrej; Simionescu, Aurora; Allen, Steven W

    2013-10-31

    Most of the metals (elements heavier than helium) produced by stars in the member galaxies of clusters currently reside within the hot, X-ray-emitting intra-cluster gas. Observations of X-ray line emission from this intergalactic medium have suggested a relatively small cluster-to-cluster scatter outside the cluster centres and enrichment with iron out to large radii, leading to the idea that the metal enrichment occurred early in the history of the Universe. Models with early enrichment predict a uniform metal distribution at large radii in clusters, whereas those with late-time enrichment are expected to introduce significant spatial variations of the metallicity. To discriminate clearly between these competing models, it is essential to test for potential inhomogeneities by measuring the abundances out to large radii along multiple directions in clusters, which has not hitherto been done. Here we report a remarkably uniform iron abundance, as a function of radius and azimuth, that is statistically consistent with a constant value of ZFe = 0.306 ± 0.012 in solar units out to the edge of the nearby Perseus cluster. This homogeneous distribution requires that most of the metal enrichment of the intergalactic medium occurred before the cluster formed, probably more than ten billion years ago, during the period of maximal star formation and black hole activity.

  14. Heavy metal distribution in dust from elementary schools in Hermosillo, Sonora, México

    NASA Astrophysics Data System (ADS)

    Meza-Figueroa, Diana; De la O-Villanueva, Margarita; De la Parra, Maria Luisa

    The city of Hermosillo, Sonora in northern Mexico was investigated for its heavy metals content. Samples of sedimented dust in roofs from 25 elementary schools were analyzed for their contents of Ni, Cr, Zn, Cd, Co, Ba, V, Pb, Fe and Cu after digestion with nitric acid. The results of the analysis were used to determine spatial distribution and magnitude of heavy metals pollution. The results of this study reveal that heavy metals distribution is different in two areas of the city. The southern area contains higher concentrations of heavy metals than the northcentral area. The mean level of Cd in exterior dust is 5.65 mg kg -1 in the southern area whereas the mean level of Cd is 2.83 mg kg -1 in the northcentral area. Elevated concentrations of Zn (2012 mg kg -1), Pb (101.88 mg kg -1), Cr (38.13 mg kg -1) and Cd (28.38 mg kg -1) in roof dust were found in samples located near industrial areas. Principal component analysis (PCA) was applied to the data matrix to evaluate the analytical results and to identify the possible pollution sources of metals. PCA shows two main sources: (1) Pb, Cd, Cr and Zn are mainly derived from industrial sources, combined with traffic sources; (2) Fe, Co and Ba are mainly derived from natural sources. V and Ni are highly correlated and possibly related to fuel combustion processes. Enrichment factors were calculated, which in turn further confirms the source identification. Ba and Co are dominantly crustal. Anthropogenically added Cd, Pb, Zn and Cr show maximum enrichment relative to the upper continental crustal component. The distribution of the heavy metals in dust does not seem to be controlled only by the topography of the city, but also by the location of the emission sources.

  15. The Metallicity Distribution Functions in Cool Stars in the SEGUE Survey

    NASA Astrophysics Data System (ADS)

    Schlesinger, Katharine

    2012-01-01

    Using the G and K dwarfs from the SEGUE Survey, we determine the metallicity distributions of cool stars in the Milky Way disk with respect to R and |Z|, which provide important guidance for models of the formation and chemical evolution of the Milky Way thick disk. Benefiting from the well-defined and quantitative target selection algorithm of SEGUE, we weight our spectroscopic sample such that it accurately represents the underlying Milky Way populations. Although we cover a limited range in R, we detect a negative metallicity gradient for both spectral types below |Z| of 1 kpc. Above this height, our samples are consistent with a flat radial metallicity gradient. The two spectral types also show similar behavior to each other in the vertical direction, showing a consistent decrease in [Fe/H] with respect to increasing |Z|. Comparison with the thin and thick disk samples, defined by [α/Fe], from Lee et al. (2011) indicates that the vertical metallicity gradient reflects the transition in G and K dwarfs from a thin-disk-dominated sample at small |Z| to a sample consisting primarily of thick-disk stars at high |Z|. We compare our distributions to those of two different Galaxy models, from TRILEGAL (Girardi et al. 2004) and Schoenrich & Binney (2009a,b). Both models show little change in [Fe/H] with respect to |Z| and are unable to replicate the low-metallicity structure we observe. Therefore, our metallicity distribution functions challenge the assumptions that go into these models, which must be modified in light of the observations.

  16. The founder of the theory of diffusionless (martensite) transformations in metallic alloys

    NASA Astrophysics Data System (ADS)

    Vintaikin, E. Z.; Nosova, G. I.

    1997-02-01

    In February 1997 G. V. Kurdyumov is to celebrate his 95th birthday. Doing justice to this wonderful scientist, we publish an article by his disciples (colleagues at the Bardin Central Research Institute of Ferrous Metallurgy) devoted to his achievements in the field of martensite transformations. We also present one of his fundamental works on martensite transformations published in 1948 in Reports of the Academy of Sciences of the USSR, Vol. 60, No. 9.

  17. [Distribution and potential ecological risk assessment of heavy metals in sediments of Zhalong Wetland].

    PubMed

    Ye, Hua-Xiang; Zang, Shu-Ying; Zhang, Li-Juan; Zhang, Yu-Hong

    2013-04-01

    This study investigated the concentrations of heavy metals in the sediments of the Zhalong Wetland using ICP-MS, analyzed their spatial distributions, evaluated the potential ecological risk, and explored the pollution sources and environmental influencing factors. The results can be summarized as the followings: (1) The concentrations of Hg, Cd, As, Cu, Pb, Zn and Cr were 0.065, 0.155, 10.26, 18.20, 21.35, 52.08 and 46.47 mg x kg(-1), respectively, which were all above the soil background values of the Songnen Plain. Their spatial distributions were distinctly different. The concentration of heavy metals in the north was higher than that in the south, and the east was higher than the west. Particularly in the eastern region, the concentrations of Hg and Cd were 20.8 and 32.4 times the minimum values of the whole area. And in the core zone, the concentration was relatively low. (2) The sequence of the potential ecological risk posed by the metals was Hg > Cd > As > Pb > Cu > Cr > Zn. The average potential ecological risk index (RI) of the Zhalong Wetland was 171.9 (ranged from 76.9-473.5), suggesting a moderate ecological risk. However, the potential ecological risk was extremely high in the east which should be treated as the major heavy metal pollution prevention site in the future. (3) Except for Hg and Pb, the concentrations of all heavy metals were significantly correlated to each other, indicating that those heavy metals had homology. (4) Organic matter was the major environmental influencing factor. However, the trend of land salinization in the Zhalong Wetland has been intensified, indicating a higher risk of heavy metal releasing from the sediments, to which the local authorities should pay enough attention.

  18. Speciation dynamics of metals in dispersion of nanoparticles with discrete distribution of charged binding sites.

    PubMed

    Polyakov, Pavel D; Duval, Jérôme F L

    2014-02-07

    We report a comprehensive theory to evaluate the kinetics of complex formation between metal ions and charged spherical nanoparticles. The latter consist of an ion-impermeable core surrounded by a soft shell layer characterized by a discrete axisymmetric 2D distribution of charged sites that bind metal ions. The theory explicitly integrates the conductive diffusion of metal ions from bulk solution toward the respective locations of the reactive sites within the particle shell volume. The kinetic constant k for outer-sphere nanoparticle-metal association is obtained from the sum of the contributions stemming from all reactive sites, each evaluated from the corresponding incoming flux of metal ions derived from steady-state Poisson-Nernst-Planck equations. Illustrations are provided to capture the basic intertwined impacts of particle size, overall particle charge, spatial heterogeneity in site distribution, type of particle (hard, core-shell or porous) and concentration of the background electrolyte on k. As a limit, k converges with predictions from previously reported analytical expressions derived for porous particles with low and high charge density, cases that correspond to coulombic and mean-field (smeared-out) electrostatic treatments, respectively. The conditions underlying the applicability of these latter approaches are rigorously identified in terms of (i) the extent of overlap between electric double layers around charged neighbouring sites, and (ii) the magnitude of the intraparticulate metal concentration gradient. For the first time, the proposed theory integrates the differentiated impact of the local potential around the charged binding sites amidst the overall particle field, together with that of the so-far discarded intraparticulate flux of metal ions.

  19. Genotoxicity and contamination of natural and anthropogenically transformed soils of the city of Rostov-on-Don with heavy metals

    NASA Astrophysics Data System (ADS)

    Gorbov, S. N.; Bezuglova, O. S.; Varduni, T. V.; Gorovtsov, A. V.; Tagiverdiev, S. S.; Hildebrant, Yu. A.

    2015-12-01

    The integrated characteristics of urban soils included the assessment of heavy metal pollution linked to the determination of soil genotoxicity, which characterizes the soil capacity to affect the structural and functional state of the genetic apparatus of soil biota. Increased concentration of chromium caused by the high background level was found in soils of the city of Rostov-on-Don. A weak contamination of surface horizons with lead and arsenic was also noted. Maximum permissible concentration of zinc was locally exceeded, including deep soil horizons. It was found that there is no definite correlation between the total content of heavy metals, their mobile compounds, and the parameters of genotoxicity in the natural and anthropogenically transformed soils. It was concluded that soil genotoxicity characterizes the total mutagenic activity associated with the presence of a set of genotoxicants of different nature.

  20. Chemical Cartography with APOGEE: Metallicity Distribution Functions and the Chemical Structure of the Milky Way Disk

    NASA Astrophysics Data System (ADS)

    Hayden, Michael R.; Bovy, Jo; Holtzman, Jon A.; Nidever, David L.; Bird, Jonathan C.; Weinberg, David H.; Andrews, Brett H.; Majewski, Steven R.; Allende Prieto, Carlos; Anders, Friedrich; Beers, Timothy C.; Bizyaev, Dmitry; Chiappini, Cristina; Cunha, Katia; Frinchaboy, Peter; García-Herńandez, D. A.; García Pérez, Ana E.; Girardi, Léo; Harding, Paul; Hearty, Fred R.; Johnson, Jennifer A.; Mészáros, Szabolcs; Minchev, Ivan; O'Connell, Robert; Pan, Kaike; Robin, Annie C.; Schiavon, Ricardo P.; Schneider, Donald P.; Schultheis, Mathias; Shetrone, Matthew; Skrutskie, Michael; Steinmetz, Matthias; Smith, Verne; Wilson, John C.; Zamora, Olga; Zasowski, Gail

    2015-08-01

    Using a sample of 69,919 red giants from the SDSS-III/APOGEE Data Release 12, we measure the distribution of stars in the [α/Fe] versus [Fe/H] plane and the metallicity distribution functions (MDFs) across an unprecedented volume of the Milky Way disk, with radius 3 < R < 15 kpc and height | z| \\lt 2 kpc. Stars in the inner disk (R < 5 kpc) lie along a single track in [α/Fe] versus [Fe/H], starting with α-enhanced, metal-poor stars and ending at [α/Fe] ˜ 0 and [Fe/H] ˜ +0.4. At larger radii we find two distinct sequences in [α/Fe] versus [Fe/H] space, with a roughly solar-α sequence that spans a decade in metallicity and a high-α sequence that merges with the low-α sequence at super-solar [Fe/H]. The location of the high-α sequence is nearly constant across the disk however, there are very few high-α stars at R > 11 kpc. The peak of the midplane MDF shifts to lower metallicity at larger R, reflecting the Galactic metallicity gradient. Most strikingly, the shape of the midplane MDF changes systematically with radius, from a negatively skewed distribution at 3 < R < 7 kpc, to a roughly Gaussian distribution at the solar annulus, to a positively skewed shape in the outer Galaxy. For stars with | z| \\gt 1 kpc or [α/Fe] > 0.18, the MDF shows little dependence on R. The positive skewness of the outer-disk MDF may be a signature of radial migration; we show that blurring of stellar populations by orbital eccentricities is not enough to explain the reversal of MDF shape, but a simple model of radial migration can do so.

  1. Airfall of metals from the Palmerton, PA, zinc plant: Distribution and preservation

    NASA Astrophysics Data System (ADS)

    Sahagian, D.; Peters, S.; Yasko, G.; Lofaro, J.; Burrows, J.; Blake, J.; Smith, K.

    2008-12-01

    The stacks of the NJ Zinc Co. created airfall deposits throughout the 20th century in the region surrounding Palmerton, PA. The deposition of zinc, cadmium, lead, and arsenic, led to the destruction of a forest ecosystem along the neighboring Kittatinny Ridge and metals contamination in the town and surrounding area. Although the smelter was closed in the 1980's, concerns linger over whether the soil still remains contaminated with elevated levels of smelter-derived metals. The present concentration and distribution of metals in the soil is the result of the initial (20th century) concentration an the processes of leaching, erosion, and biological uptake and dispersal that have proceeded since the smelter was shut down. At the site of the smelter, analyses of samples from 141 shallow soil pits had zinc concentrations up to 95 mg/kg, with a mean value of 14 mg/kg. Lead concentrations in the same soils had concentrations ranging up to 250 mg/kg, with a mean value of 72 mg/kg. We have now sampled a suite of soils from the "far field" region up to 25 km away from the smelter site to determine the spatial extent of remaining metals contamination. We dug soil pits and collected samples from the shallow O-horizon, the underlying A horizon (typically 2-4 cm depth), and the B-horizon at about 20-30 cm to determine not only the geographic distributions of metals, but also the depths at which these different metals are now found in the subsurface. The far field data distribution can now provide information for local communities regarding soils chemistry and help to guide land use practices within residential, business, and agricultural properties throughout the region. Concerns regarding contamination from metals airfall have played a role in depressing local economies, further exacerbating and perpetuating the economic impact of the closure of the smelter itself. Our analyses can potentially ameliorate such concerns by providing the actual distribution and concentrations of

  2. Distribution of the current on metallic structures with corrosion damage under nonlinear cathodic polarization

    SciTech Connect

    Galimov, A.A.; Glazov, N.P.; Ivanov, V.T.

    1985-08-01

    The protection of metallic structures from corrosion is effected by cathodic polarization and protective coatings. At sites of damage extending through the insulation an intense corrosion process, which causes the formation of corrosion pits, in which signifiant redistribution of the protective current occurs, takes place. Considered in this paper is the distribution of the current on an electrode with a corrosion pit of arbitrary shape in the example of an electrochemical system consisting of disk electrodes located in a cylindrical bath with a lateral insulator surface. The overall analysis of the numerical results points out the significant redistribution of the current on a protected metallic surface when corrosion pits appear.

  3. Effect of Jig Design and Assessment of Stress Distribution in Testing Metal-Ceramic Adhesion.

    PubMed

    Özcan, Mutlu; Kojima, Alberto Noriyuki; Nishioka, Renato Sussumu; Mesquita, Alfredo Mikail Melo; Bottino, Marco Antonio; Filho, Gilberto Duarte

    2016-12-01

    In testing adhesion using shear bond test, a combination of shear and tensile forces occur at the interface, resulting in complex stresses. The jig designs used for this kind of test show variations in published studies, complicating direct comparison between studies. This study evaluated the effect of different jig designs on metal-ceramic bond strength and assessed the stress distribution at the interface using finite element analysis (FEA). Metal-ceramic (Metal: Ni-Cr, Wiron 99, Bego; Ceramic: Vita Omega 900, Vita) specimens (N = 36) (diameter: 4 mm, veneer thickness: 4 mm; base diameter: 5 mm, thickness: 1 mm) were fabricated and randomly divided into three groups (n = 12 per group) to be tested using one of the following jig designs: (a) chisel (CH) (ISO 11405), (b) steel strip (SS), (c) piston (PI). Metal-ceramic interfaces were loaded under shear until debonding in a universal testing machine (0.5 mm/min). Failure types were evaluated using scanning electron microscopy (SEM). FEA was used to study the stress distribution using different jigs. Metal-ceramic bond strength data (MPa) were analyzed using ANOVA and Tukey's tests (α = 0.05). The jig type significantly affected the bond results (p = 0.0001). PI type of jig presented the highest results (MPa) (p < 0.05) (58.2 ± 14.8), followed by CH (38.7 ± 7.6) and SS jig type (23.3 ± 4.2) (p < 0.05). Failure types were exclusively a combination of cohesive failure in the opaque ceramic and adhesive interface failure. FEA analysis indicated that the SS jig presented slightly more stress formation than with the CH jig. The PI jig presented small stress concentration with more homogeneous force distribution compared to the CH jig where the stress concentrated in the area where the force was applied. Metal-ceramic bond strength was affected by the jig design. Accordingly, the results of in vitro studies on metal-ceramic adhesion should be evaluated with caution. When adhesion of ceramic materials to metals is

  4. The Stellar Metallicity Distribution of the Galactic Halo Based on SCUSS and SDSS Data

    NASA Astrophysics Data System (ADS)

    Zuo, Wenbo; Du, Cuihua; Jing, Yingjie; Gu, Jiayin; Newberg, Heidi Jo; Wu, Zhenyu; Ma, Jun; Zhou, Xu

    2017-05-01

    Based on the Sloan Digital Sky Survey and South Galactic Cap u-band Sky Survey (SCUSS), we simulate the photometric metallicity distribution functions (MDFs) of stars in the Galactic halo. The photometric metallicity of stars was estimated by a new Monte-Carlo method. Due to the use of a more reliable metallicity calibration method and more accurate u-band deep measurements from SCUSS, we can obtain more accurate MDFs of a large sample of distant stars in the Galactic halo. In this study, we select 78,092 F/G main-sequence turnoff stars (MSTO) in the south Galactic cap, with 0.2 < (g - r)0 < 0.4, as tracers of the stellar MDFs in the Galactic halo. The sample stars are divided into two height intervals above the Galactic plane: -8 < z < -4 kpc and -12 < z < -8 kpc. The MDFs of selected stars in each interval are well fit by a three-Gaussian model, with peaks at [Fe/H] ≈ -0.63, -1.45, and -2.0. The two metal-poor components correspond to the inner halo and outer halo, respectively. The fraction of the metal-rich component, which may be contributed by the substructure (such as Sagittarius stream or other streams) is about 10%. With limited kinematic estimation, we find the correlations between metallicity and kinematics. Our results provide additional supporting evidence of duality of the Galactic halo.

  5. Metal concentrations and distribution in paint waste generated during bridge rehabilitation in New York State.

    PubMed

    Shu, Zhan; Axe, Lisa; Jahan, Kauser; Ramanujachary, Kandalam V; Kochersberger, Carl

    2015-09-01

    Between 1950 and 1980, lead and chromium along with other metals have been used in paint coatings to protect bridges from corrosion. In New York State with 4500 bridges in 11 Regions 2385 of the bridges have been rehabilitated and subsequently repainted after 1989 when commercial use of lead based paint was prohibited. The purpose of this research was to address the concentration and distribution of trace metals in the paint waste generated during bridge rehabilitation. Using hypothesis testing and stratified sampling theory, a representative sample size of 24 bridges from across the state was selected that resulted in 117 paint waste samples. Field portable X-ray fluorescence (FP-XRF) analysis revealed metal concentrations ranged from 5 to 168,090 mg kg(-1) for Pb, 49,367 to 799,210 mg kg(-1) for Fe, and 27 to 425,510 mg kg(-1) for Zn. Eighty percent of the samples exhibited lead concentrations greater than 5000 mg kg(-1). The elevated iron concentrations may be attributed to the application of steel grit as an abrasive blasting material routinely used by state Departments of Transportation in the paint removal process. Other metals including Ba and Cr were observed in the paint waste as well. As a result of the paint formulation, metals were found to be associated in the paint waste (Pb correlated with Cr (r=0.85)). The elevated metal concentrations observed raises concern over the potential impact of leaching from this waste stream.

  6. Distribution of the concentration of heavy metals associated with the sediment particles accumulated on road surfaces.

    PubMed

    Zafra, C A; Temprano, J; Tejero, I

    2011-07-01

    The heavy metal pollution caused by road run-off water constitutes a problem in urban areas. The metallic load associated with road sediment must be determined in order to study its impact in drainage systems and receiving waters, and to perfect the design of prevention systems. This paper presents data regarding the sediment collected on road surfaces in the city of Torrelavega (northern Spain) during a period of 65 days (132 samples). Two sample types were collected: vacuum-dried samples and those swept up following vacuuming. The sediment loading (g m(-2)), particle size distribution (63-2800 microm) and heavy metal concentrations were determined. The data showed that the concentration of heavy metals tends to increase with the reduction in the particle diameter (exponential tendency). The concentrations ofPb, Zn, Cu, Cr, Ni, Cd, Fe, Mn and Co in the size fraction <63 microm were 350, 630, 124, 57, 56, 38, 3231, 374 and 51 mg kg(-1), respectively (average traffic density: 3800 vehicles day(-1)). By increasing the residence time of the sediment, the concentration increases, whereas the ratio of the concentration between the different size fractions decreases. The concentration across the road diminishes when the distance between the roadway and the sampling siteincreases; when the distance increases, the ratio between size fractions for heavy metal concentrations increases. Finally, the main sources of heavy metals are the particles detached by braking (brake pads) and tyre wear (rubber), and are associated with particle sizes <125 microm.

  7. [Spatial distribution and contamination evaluation of heavy metals in the intertidal surface sediments of Eastern Chongming].

    PubMed

    Li, Ya-Juan; Yang, Shi-Lun; Hou, Li-Jun; Zhou, Ju-Zhen; Liu, Ying-Wen

    2012-07-01

    Using the ArcGIS geostatistical analysis module, this work investigated the spatial distribution pattern of heavy metals (Cu, Pb, Zn, Cr, Cd) and their deposition fluxes in the intertidal surface sediments of Eastern Chongming based on the analysis of grain size, heavy metal concentrations and organic carbon content. The spatial interpolation (Kriging) was performed to estimate the deposition fluxes, and the contamination status of heavy metals was evaluated using geoaccumulation index and potential ecological risk index. The results showed that the average contents of Cu, Pb, Zn, Cr and Cd were 42, 27, 69, 71 and 0.23 microg x g(-1), respectively, all of which exceeded the background value in the Shanghai tidal flat. The contents of heavy metals showed a landward as well as northward increasing trend due to the influences of sediment grain size and organic carbon content. The annual deposition of Cu, Pb, Zn, Cr and Cd in Eastern Chongming were 187, 121, 395, 312 and 1.04 t, respectively; the total deposition flux of these heavy metals was 11 g x (m2 x a)-1. Although the overall contamination level of heavy metals in Eastern Chongming was relatively low, Cd, Pb and Cu had a potential pollution threat to the sediment environment.

  8. Metal-Organic Frameworks Stabilize Solution-Inaccessible Cobalt Catalysts for Highly Efficient Broad-Scope Organic Transformations.

    PubMed

    Zhang, Teng; Manna, Kuntal; Lin, Wenbin

    2016-03-09

    New and active earth-abundant metal catalysts are critically needed to replace precious metal-based catalysts for sustainable production of commodity and fine chemicals. We report here the design of highly robust, active, and reusable cobalt-bipyridine- and cobalt-phenanthroline-based metal-organic framework (MOF) catalysts for alkene hydrogenation and hydroboration, aldehyde/ketone hydroboration, and arene C-H borylation. In alkene hydrogenation, the MOF catalysts tolerated a variety of functional groups and displayed unprecedentedly high turnover numbers of ∼2.5 × 10(6) and turnover frequencies of ∼1.1 × 10(5) h(-1). Structural, computational, and spectroscopic studies show that site isolation of the highly reactive (bpy)Co(THF)2 species in the MOFs prevents intermolecular deactivation and stabilizes solution-inaccessible catalysts for broad-scope organic transformations. Computational, spectroscopic, and kinetic evidence further support a hitherto unknown (bpy(•-))Co(I)(THF)2 ground state that coordinates to alkene and dihydrogen and then undergoing σ-complex-assisted metathesis to form (bpy)Co(alkyl)(H). Reductive elimination of alkane followed by alkene binding completes the catalytic cycle. MOFs thus provide a novel platform for discovering new base-metal molecular catalysts and exhibit enormous potential in sustainable chemical catalysis.

  9. Synthesis of Stereoisomeric - Metal Complexes Using Phase-Transfer Catalysis and Photochemical Transforms.

    DTIC Science & Technology

    1984-05-25

    necessar" and Identify by block number) [-.-.𔃽rganic chemistry -"rganometallic compounds Transition metal compounds. -- Photochemistry . 20. ABSTRACT...atmosphere of prepurified nitrogen. Benzene and pentane were distilled over sodium prior to use. Tetrahydrofuran was distilled from sodium benzophenone

  10. Grenade Range Management Using Lime for Dual Role of Metals Immobilization and Explosives Transformation

    DTIC Science & Technology

    2007-11-01

    metals. The munitions constituents of concern to this study were RDX and metals, particularly iron and zinc. During the course of the 20-month...monitor changes in pore water with lime treatment. Both HGRs had surface water samplers placed at the edge of the bays to collect surface water as it...stabilized in the soil, with reduction in the concentrations of both iron and zinc leaving the range via surface water and leachate. There was

  11. Grenade Range Management Using Lime for Metals Immobilization and Explosives Transformation Treatability Study

    DTIC Science & Technology

    2007-06-01

    Calcitic hydrated lime K2CO3 Potassium carbonate KOH Potassium hydroxide NaOH Sodium hydroxide NH3-N Nitrogen-ammonia NO2/NO3 Nitrite/nitrate...munitions residues, metals are not degraded or easily detoxified. The most com- monly used treatment technologies for metals in soils on firing ranges...of an active firing range. Alkaline hydrolysis The use of the hydrolysis reaction as a means to degrade various environ- mental contaminants is

  12. Influence of Metal of the Applicator on the Dose Distribution during Brachytherapy

    PubMed Central

    Wu, Chin-Hui; Shiau, An-Cheng; Liao, Yi-Jen; Lin, Hsin-Yu

    2014-01-01

    This study explores how the metal materials of the applicator influence the dose distribution when performing brachytherapy for cervical cancer. A pinpoint ionization chamber, Monte Carlo code MCNPX, and treatment planning system are used to evaluate the dose distribution for a single Ir-192 source positioned in the tandem and ovoid. For dose distribution in water with the presence of the tandem, differences among measurement, MCNPX calculation and treatment planning system results are <5%. For dose distribution in water with the presence of the ovoid, the MCNPX result agrees with the measurement. But the doses calculated from treatment planning system are overestimated by up to a factor of 4. This is due to the shielding effect of the metal materials in the applicator not being considered in the treatment planning system. This result suggests that the treatment planning system should take into account corrections for the metal materials of the applicator in order to improve the accuracy of the radiation dose delivered. PMID:25133789

  13. Simulation of the impact of 3-D porosity distribution in metallic U-10Zr fuels

    NASA Astrophysics Data System (ADS)

    Yun, Di; Yacout, Abdellatif M.; Stan, Marius; Bauer, Theodore H.; Wright, Arthur E.

    2014-05-01

    Evolution of porosity generated in metallic U-Zr fuel irradiated in fast spectrum reactors leads to changes in fuel properties and impacts important phenomena such as heat transport and constituent redistribution. The porosity is generated as a result of the accumulation of fission gases and is affected by the possible bond sodium infiltration into the fuel. Typically, the impact of porosity development on properties, such as thermal conductivity, is accounted for through empirical correlations that are dependent on porosity and infiltrated sodium fractions. Currently available simulation tools make it possible to take into account fuel 3-D porosity distributions, potentially eliminating the need for such correlations. This development allows for a more realistic representation of the porosity evolution in metallic fuel and creates a framework for truly mechanistic fuel development models. In this work, COMSOL multi-physics simulation platform is used to model 3-D porosity distributions and simulate heat transport in metallic U-10Zr fuel. Available experimental data regarding microstructural evolution of fuel that was irradiated in EBR-II and associated phase stability information are used to guide the simulation. The impact of changes in porosity characteristics on material properties is estimated and the results are compared with calculated temperature distributions. The simulations demonstrate the developed capability and importance of accounting for detailed porosity distribution features for accurate fuel performance evaluation.

  14. Supplement to the ``determination analysis`` (ORNL-6847) and analysis of the NEMA efficiency standard for distribution transformers

    SciTech Connect

    Barnes, P.R.; Das, S.; McConnell, B.W.; Van Dyke, J.W.

    1997-09-01

    This report contains additional information for use by the US Department of Energy in making a determination on proposing energy conservation standards for distribution transformers as required by the Energy Policy Act of 1992. An earlier determination study by the Oak Ridge National Laboratory determined that cost-effective, technically feasible energy savings could be achieved by distribution transformer standards and that these savings are significant relative to other product conservation standards. This study was documented in a final report, ``Determination Analysis of Energy Conservation Standards for Distribution Transformers`` (ORNL-6847, July 1996). The energy conservation options analyzed in this study were estimated to save 5.2 to 13.7 quads from 2000--2030. The energy savings for the determination study cases have been revised downward for a number of reasons. The transformer market, both present and future, was overestimated in the previous study, particularly for dry-type transformers, which have the greatest energy-saving potential. Moreover, a revision downwards of the effective annual loads for utility owned transformers also results in lower energy savings. The present study assesses four of the five conservation cases from the earlier determination study as well as the National Electrical Manufacturers Association energy efficiency standard NEMA TP 1-1996 using the updated data and a more accurate disaggregated analysis model. According to these new estimates, the savings ranged from 2.5 to 10.7 quads of primary energy for the 30-year period 2004 to 2034. For the TP-1 case, data were available to calculate the payback period required to recover the extra cost from the value of the energy saved. The average payback period based on the average national cost of electricity is 2.76 years. 15 figs., 23 tabs.

  15. Metal and Nutrient Distribution and Fractionation in Managed Urban Watersheds Across the US Southwest

    NASA Astrophysics Data System (ADS)

    Papelis, C.; Williams, A. C.; Boettcher, T. M.

    2008-12-01

    Metals, metalloids, and nutrients are common contaminants of concern in arid and semi-arid watersheds in the Southwestern U.S. Because of the dramatic population growth in this part of the U.S., the potential for contamination of urban watersheds has also increased over the last few decades. Streams in urban watersheds receive storm water, urban runoff, shallow groundwater, and treated wastewater, among other sources. In addition, urban watersheds are often heavily managed to mitigate flood events and sediment- related impacts. Sediment transport can have a profound effect on the water quality of affected bodies of water. However, differences in geology, hydrogeology, and land use may have dramatic effects on the distribution of nutrients and metals in different urban watersheds. To test these effects, aqueous and sediment samples were collected above and below erosion control and other structures along two heavily managed urban watersheds, namely the Las Vegas Wash in the Las Vegas Valley Watershed, Nevada, and the Rio Salado (Salt River) in the Phoenix Metropolitan Area, Arizona. The construction of such control structures has the potential to alter the distribution of metals and metalloids in bodies of water used by wildlife. In this study, all sediments were characterized by particle size distribution, specific surface area, mineralogical composition, and scanning electron microscopy. The results of total arsenic, boron, and phosphorus extractions will be discussed, as a function of sediment characteristics. Significant differences exist between the two U.S. Southwest watersheds studied, including land use, water sources, sediment characteristics, nutrient and metal distribution, and overall system complexity. These differences lead to significant variations in metalloid and nutrient distributions in the two watersheds. Differences and similarities in the two systems will be explained as a function of sediment characteristics and watershed properties.

  16. Spatial distribution of heavy metals in surface soil, plant and mushroom beside high-frequency road

    NASA Astrophysics Data System (ADS)

    Krbić, Biljana Å.; Milovac, Snežana; Stošić, Dušan; Zorić, Miroslav; Matavulj, Milan

    2010-05-01

    One of the undesirable aspects of urbanization process is the introduction of potentially harmful pollutants into environment. Urban soils are often contaminated by metals deriving from industry, transportation and other human activities. In this study, concentration of heavy metals were investigated in roadside surface soil, linden tree bark (Tilia sp.), mushroom Schizophyllum commune and dust samples collected at different distances (0.2 - 200 m) from main high-frequency road. The samples were microwave digested in accordance to US EPA 3051 method and analyzed by flame (Cd, Cu, Co, Fe, Ni, Mn, Pb and Zn), graphite furnace (Cr) and cold vapor (Hg) atomic absorption spectrometry. The results of the analysis were used to determine major sources and distribution of heavy metals pollution. The obtained results showed significant decrease of traffic-related metals (Fe, Zn, Pb, Ni, Cu and Cd) in soil samples with increasing distance from road edge. In order to assess possible pollution, heavy metal contents in soil were compared with the National legislation and Netherlands soil quality standards. Also, elevated concentrations of traffic-related metals, especially Pb and Cr in analyzed tree bark, mushroom and dust samples, indicate the obvious roadside contamination whose primary contributors appear to be vehicular local traffic. In addition, Index of Bioaccumulation (IBA) was calculated in order to estimate plant and mushroom ability of heavy metals accumulation. Assessment of statistical differences among samples was performed by one-way analysis of variance (ANOVA) and Tukey honestly significant difference (HSD) test. Moreover, Principal Component Analysis (PCA) was performed on the heavy metals content allowed a meaningful classification of the samples according to the main sources of pollution.

  17. Utilizing platforms for the observation of chemical transformations to surface-bound noble metal nanoparticles in environmentally relevant conditions

    NASA Astrophysics Data System (ADS)

    Glover, Richard David

    Nanoparticles are increasingly incorporated into consumer products because of their unique, size-dependent properties. Although these properties are commercially appealing, data are lacking regarding the fate and reactivity of nanoparticles once incorporated into materials. This information gap prevents accurate assessment of hazards that these materials potentially present to consumers and the environment. To address this concern, new research is needed to investigate the reactivity and transformations of nanoparticles. This dissertation describes the use of an electron transparent characterization platform to observe nanoparticle transformations. Nanoparticles were tethered to the surface of an analysis platform, exposed to a variety of conditions, and evaluated for reactivity and response. The characterization of silver nanoparticles revealed the generation of new daughter nanoparticles on surfaces in ambient humid conditions. Our observations showed that the transport of material is highly dependent on relative humidity and that pH equilibria drives the deposition of new particles and degradation. We discovered, by applying these findings to macro-silver objects, that bulk silver generates new nanoparticles on surfaces. This illuminated the possibility of other, yet undiscovered, naturally occurring nanoparticles. In the second model system, 1.5 nm gold nanoparticles were tethered by a robust metal oxide bond from the terminal group of the stabilizing ligand. This strategy facilitated precise control over thiol ligand removal using a dilute ozone oxidation. Tracking particle oxidation over time allowed us to gain unprecedented control over core exposure, size maintenance, and surface tethering. This platform was also utilized as a proof-of-concept for direct observation of transformations in complex media. Ligand and core transformations were monitored in a variety of biologically relevant conditions using tethered nanoparticles. Morphological and chemical

  18. Transformation of metal-organic framework to polymer gel by cross-linking the organic ligands preorganized in metal-organic framework.

    PubMed

    Ishiwata, Takumi; Furukawa, Yuki; Sugikawa, Kouta; Kokado, Kenta; Sada, Kazuki

    2013-04-10

    Until now, seamless fusion of metal-organic frameworks (MOFs) and covalently cross-linked polymer gels (PG) at molecular level has been extremely rare, since these two matters have been regarded as opposite, that is, hard versus soft. In this report, we demonstrate transformation of cubic MOF crystals to PG via inner cross-linking of the organic linkers in the void space of MOF, followed by decomposition of the metal coordination. The obtained PG behaved as a polyelectrolyte gel, indicating the high content of ionic groups inside. Metal ions were well adsorbed in the PG due to its densely packed carboxylate groups. A chimera-type hybrid material consisting of MOF and PG was obtained by partial hydrolysis of resulting cross-linked MOF. The shape of resulting PG network well reflected the crystal structure of MOF employed as a template. Our results will connect the two different network materials that have been ever studied in the two different fields to provide new soft and hard hybrid materials, and the unique copolymerization in the large void space of the MOF will open a new horizon toward "ideal network polymers" never prepared before now.

  19. Distributed fiber-optic sensor for real-time monitoring of energized transformer cores

    NASA Astrophysics Data System (ADS)

    Lu, Ping; Byerly, Kevin; Buric, Michael; Zandhuis, Paul; Sun, Chenhu; Leary, A.; Beddingfield, R.; McHenry, M. E.; Ohodnicki, Paul R.

    2017-05-01

    Real-time temperature mapping is important to offer an optimized thermal design of efficient power transformers by solving local overheating problems. In addition, internal temperature monitoring of power transformers in operation can be leveraged for asset monitoring applications targeted at fault detection to enable condition based maintenance programs. However transformers present a variety of challenging environments such as high levels of electromagnetic interference and limited space for conventional sensing systems to operate. Immersion of some power transformers within insulation oils for thermal management during operation and the presence of relatively large and time varying electrical and magnetic fields in some cases also make sensing and measurement technologies that require electrical wires or active power at the sensing location highly undesirable. In this work, we investigate the dynamic thermal response of standard single-mode optical fiber instrumented on a compact transformer core by using an optical frequency-domain reflectometry scheme, and the spatially resolved on-line monitoring of transformer core temperature rise has been successfully demonstrated. It is found that spectral shifts of the fiber-optic sensor induced by the temperature rises are strongly related to the locations inside the transformer as would be expected. Correlation between thermal behavior of the transformer core as derived from standard IR-based thermal imaging cameras and fiber-optic sensing results is also discussed. The proposed method can easily be extended to cover situations in which high accuracy and high spatial resolution thermal surveillance are required, and offers the potential for unprecedented optimization of magnetic core designs for power transformer applications as well as a novel approach to power transformer asset monitoring.

  20. Label-free colorimetric detection of mercury via Hg2+ ions-accelerated structural transformation of nanoscale metal-oxo clusters

    PubMed Central

    Chen, Kun; She, Shan; Zhang, Jiangwei; Bayaguud, Aruuhan; Wei, Yongge

    2015-01-01

    Mercury and its compounds are known to be extremely toxic but widely distributed in environment. Although many works have been reported to efficiently detect mercury, development of simple and convenient sensors is still longed for quick analyzing mercury in water. In this work, a nanoscale metal-oxo cluster, (n-Bu4N)2[Mo5NaO13(OCH3)4(NO)], (MLPOM), organically-derivatized from monolacunary Lindqvist-type polyoxomolybdate, is found to specifically react with Hg2+ in methanol/water via structural transformation. The MLPOM methanol solution displays a color change from purple to brown within seconds after being mixed with an aqueous solution containing Hg2+. By comparing the structure of polyoxomolybdate before and after reaction, the color change is revealed to be the essentially structural transformation of MLPOM accelerated by Hg2+. Based on this discovery, MLPOM could be utilized as a colorimetric sensor to sense the existence of Hg2+, and a simple and label-free method is developed to selectively detect aqueous Hg2+. Furthermore, the colorimetric sensor has been applied to indicating mercury contamination in industrial sewage. PMID:26559602

  1. Label-free colorimetric detection of mercury via Hg2+ ions-accelerated structural transformation of nanoscale metal-oxo clusters

    NASA Astrophysics Data System (ADS)

    Chen, Kun; She, Shan; Zhang, Jiangwei; Bayaguud, Aruuhan; Wei, Yongge

    2015-11-01

    Mercury and its compounds are known to be extremely toxic but widely distributed in environment. Although many works have been reported to efficiently detect mercury, development of simple and convenient sensors is still longed for quick analyzing mercury in water. In this work, a nanoscale metal-oxo cluster, (n-Bu4N)2[Mo5NaO13(OCH3)4(NO)], (MLPOM), organically-derivatized from monolacunary Lindqvist-type polyoxomolybdate, is found to specifically react with Hg2+ in methanol/water via structural transformation. The MLPOM methanol solution displays a color change from purple to brown within seconds after being mixed with an aqueous solution containing Hg2+. By comparing the structure of polyoxomolybdate before and after reaction, the color change is revealed to be the essentially structural transformation of MLPOM accelerated by Hg2+. Based on this discovery, MLPOM could be utilized as a colorimetric sensor to sense the existence of Hg2+, and a simple and label-free method is developed to selectively detect aqueous Hg2+. Furthermore, the colorimetric sensor has been applied to indicating mercury contamination in industrial sewage.

  2. Distribution of Heavy Metal Pollution in Surface Soil Samples in China: A Graphical Review.

    PubMed

    Duan, Qiannan; Lee, Jianchao; Liu, Yansong; Chen, Han; Hu, Huanyu

    2016-09-01

    Soil pollution in China is one of most wide and severe in the world. Although environmental researchers are well aware of the acuteness of soil pollution in China, a precise and comprehensive mapping system of soil pollution has never been released. By compiling, integrating and processing nearly a decade of soil pollution data, we have created cornerstone maps that illustrate the distribution and concentration of cadmium, lead, zinc, arsenic, copper and chromium in surficial soil across the nation. These summarized maps and the integrated data provide precise geographic coordinates and heavy metal concentrations; they are also the first ones to provide such thorough and comprehensive details about heavy metal soil pollution in China. In this study, we focus on some of the most polluted areas to illustrate the severity of this pressing environmental problem and demonstrate that most developed and populous areas have been subjected to heavy metal pollution.

  3. Distribution and Pollution Characteristics Analysis of Heavy Metals in Surface Sediment in Bi River

    NASA Astrophysics Data System (ADS)

    Huang, Qianrui; Danek, Tomas; Cheng, Xianfeng; Dong, Tao; Qi, Wufu; Zou, Liling; Zhao, Xueqiong; Zhao, Xinliang; Xiang, Yungang

    2016-10-01

    The author analyzes distribution characteristics of heavy metals’ content in surface sediments of Bi River (Cu, Zn, As and Cd) and evaluates the potential ecological harm of heavy metal pollution in surface sediment by index method of potential ecological harm. Results show that heavy metals, such as Cu, Zn, As, Pb and Cd in surface sediments of Bi River are badly out of limitation. Especially, the heavy metals’ content in Jinding mining area is far higher than the national first class standard. The content of heavy metal is still high in the intersection of Bi River and Lancang River, which have certain influence on the Lancang River sediment and its water system. And, Pb and Cd, as the main pollutants, should be regarded as a key research subject.

  4. Fraction distribution and risk assessment of heavy metals and trace elements in sediments of Lake Uluabat.

    PubMed

    Katip, Aslıhan; Karaer, Feza; Başkaya, Hüseyin Savaş; Ileri, Saadet; Sarmaşik, Sonay

    2012-09-01

    To examine the status and risk of heavy metal pollution, the distribution of As, Cd, Cr, Ni, and Pb in the sediment of Lake Uluabat was characterized. The present study used a four-stage method to assess the ecotoxicological effects of the heavy metal and trace elements fractions in the sediment of Lake Uluabat. Total Cr and Ni concentrations in the sediment were determined to have exceeded the severe effect level (SEL) limit values. The percentages of the variable fractions of Cr and Ni were below 10%. Because of this reason, they were not defined to have a high risk. The relationships among the physicochemical parameters, heavy metals and trace elements in water and sediment were determined statistically. Pb, Cd, and As in the water were found in relation with some of the fractions. Moreover, it was thought that the amounts of the elements of As releasing into the water might be increased due to their relations with the physicochemical parameters.

  5. [Impact of heavy metals pollution on the community structure and spatial distribution of soil animals].

    PubMed

    Sun, Xian-Bin; Liu, Hong-Yu; Li, Yu-Cheng; Zhang, Xiao-Ping

    2007-09-01

    By sampling at 8 plots surrounding the coal-mining and coal-ash areas in Huannan City of Anhui Province, a total of 3859 individuals of soil macro-, meso-, and micro-fauna belonging to 22 groups, 9 classes and 4 phyla were collected. The dominant groups were Collembola, Acarina and Nematoda, accounting for 74% of the total, and the others were frequent and rare groups. Heavy metals pollution had powerful impact on soil animals. The individual numbers and groups of soil animals declined with the aggravation of heavy metals pollution from out of the dam site to the nearing site of coal-ash area in Luohe Power Plant, and showed an abnormal distribution or little change in vertical and disappeared in surface layer. The heavy metals pollution resulted in a decline in the diversity index, evenness and density-group index, but a rise in the dominance index of soil animals.

  6. Synthesis of offset dual reflector antennas transforming a given feed illumination pattern into a specified aperture distribution

    NASA Technical Reports Server (NTRS)

    Mittra, R.; Galindo-Israel, V.; Hyjazie, F.

    1982-01-01

    The problem of transforming a given primary feed pattern into a desired aperture field distribution through two reflections by an offset dual reflector system is investigated using the concepts of geometrical optics. A numerically rigorous solution for the reflector surfaces is developed which realizes an exact aperture phase distribution and an aperture amplitude distribution that is accurate to within an arbitrarily small numerical tolerance. However, this procedure does not always yield a smooth solution, i.e., the reflector surfaces thus realized may not be continuous or their slopes may vary too rapidly. In the event of nonexistence of a numerically rigorous smooth solution, an approximate solution that enforces the smoothness of the reflector surfaces can be obtained. In the approximate solution, only the requirement for the aperture amplitude distribution is relaxed, and the condition on the aperture phase distribution is continued to be satisfied exactly.

  7. Impact of quasi-dc currents on three-phase distribution transformer installations. Power Systems Technology Program

    SciTech Connect

    McConnell, B.W.; Barnes, P.R.; Tesche, F.M.; Schafer, D.A.

    1992-06-01

    This report summarizes a series of tests designed to determine the response of quasi-dc currents on three-phase power distribution transformers for electric power systems. In general, if the dc injection is limited to the primary side of a step-down transformer, significant harmonic distortion is noted and an increase in the reactive power demand results. For dc injection on the secondary (load) side of the step-down transformer the harmonic content at the secondary side is quite high and saturation occurs with a relatively low level of dc injection; however, the reactive power demand is significantly lower. These tests produced no apparent damage to the transformers. Transformer damage is dependent on the duration of the dc excitation, the level of the excitation, and on thermal characteristics of the transfer. The transformer response time is found to be much shorter than seen in power transformer tests at lower dc injection levels. This shorter response time suggests that the response time is strongly dependent on the injected current levels, and that higher levels of dc injection for shorter durations could produce very high reactive power demands and harmonic distortion within a few tenths of a second. The added reactive power load could result in the blowing of fuses on the primary side of the transformer for even moderate dc injection levels, and neutral currents are quite large under even low-level dc injection. This ``smoking neutral`` results in high-level harmonic injection into equipment via the neutral and in possible equipment failure.

  8. Distribution of heavy metals in road dust along an urban-rural gradient in Massachusetts

    NASA Astrophysics Data System (ADS)

    Apeagyei, Eric; Bank, Michael S.; Spengler, John D.

    2011-04-01

    Human exposures to particulate matter emitted from on-road motor vehicles include complex mixtures of metals from tires, brakes, parts wear and resuspended road dust. The aim of this study was to assess road dust for metals associated with motor vehicle traffic, particularly those metals coming from brake and tire wears. We hypothesized that the road dust would show significant difference in both composition and concentration by traffic type, road class and by location. X-ray fluorescence (XRF) analyses of 115 parked car tires showed Zn and Ca were likely associated with tire wear dust. XRF results of three used brake pads indicated high concentrations of Fe, Ti, Cu, Ba, Mo and Zr. To assess heavy metal exposures associated with tires and brake wear adjacent to roads of varying traffic and functional classes, 85 samples of road dust were collected from road surfaces adjacent to the curb and analyzed by XRF. Median concentrations for Fe, Ca and K were greater than Ti (1619 ppm), with concentration ratios of Fe: Ca: K: Ti [16:5:3:1]. Cumulative frequency distribution graphs showed distribution of Fe, Ba, Cu, and Mo were similar regardless of road traffic rating. However, Zn, Ti, and Zr varied significantly ( p < 0.05) with traffic ratings of roadways (heavy > moderate > low traffic). Fe, Ba, Cu, and Mo also had similar distributions regardless of road class while composition of Zn, Ti, and Zr varied significantly across road class ( p < 0.05) (Major roads > Minor roads > highway). In comparing urban road dust to rural road dust, we observed Fe, Ca, K, and Ti were significantly greater in urban road dust ( p < 0.05). In urban road dust the Fe: Ca: K: Ti relationship with median Ti of 2216 ppm was 12: 6: 3.5: 1. These results indicate that roadway dust may be important sources of metals for runoff water and localized resuspended particulate matter.

  9. Stability and heavy metal distribution of soil aggregates affected by application of apatite, lime, and charcoal.

    PubMed

    Cui, Hongbiao; Ma, Kaiqiang; Fan, Yuchao; Peng, Xinhua; Mao, Jingdong; Zhou, Dongmei; Zhang, Zhongbin; Zhou, Jing

    2016-06-01

    Only a few studies have been reported on the stability and heavy metal distribution of soil aggregates after soil treatments to reduce the availability of heavy metals. In this study, apatite (22.3 t ha(-1)), lime (4.45 t ha(-1)), and charcoal (66.8 t ha(-1)) were applied to a heavy metal-contaminated soil for 4 years. The stability and heavy metal distribution of soil aggregates were investigated by dry and wet sieving. No significant change in the dry mean weight diameter was observed in any treatments. Compared with the control, three-amendment treatments significantly increased the wet mean weight diameter, but only charcoal treatment significantly increased the wet aggregate stability. The soil treatments increased the content of soil organic carbon, and the fraction 0.25-2 mm contained the highest content of soil organic carbon. Amendments' application slightly increased soil total Cu and Cd, but decreased the concentrations of CaCl2 -extractable Cu and Cd except for the fraction <0.053 mm. The fractions >2 and 0.25-2 mm contained the highest concentrations of CaCl2-extractable Cu and Cd, accounted for about 74.5-86.8 % of CaCl2-extractable Cu and Cd in soil. The results indicated that amendments' application increased the wet soil aggregate stability and decreased the available Cu and Cd. The distribution of available heavy metals in wet soil aggregates was not controlled by soil aggregate stability, but possibly by soil organic carbon.

  10. Concentrations and distributions of metals associated with dissolved organic matter from the Suwannee River (GA, USA)

    USGS Publications Warehouse

    Kuhn, M. Keshia; Neubauer, Elisabeth; Hofmann, Thilo; von der Kammer, Frank; Aiken, George R.; Maurice, Patricia A.

    2015-01-01

    Concentrations and distributions of metals in Suwannee River (SR) raw filtered surface water (RFSW) and dissolved organic matter (DOM) processed by reverse osmosis (RO), XAD-8 resin (for humic and fulvic acids [FA]), and XAD-4 resin (for “transphilic” acids) were analyzed by asymmetrical flow field-flow fractionation (AsFlFFF). SR samples were compared with DOM samples from Nelson's Creek (NLC), a wetland-draining stream in northern Michigan; previous International Humic Substances Society (IHSS) FA and RO samples from the SR; and an XAD-8 sample from Lake Fryxell (LF), Antarctica. Despite application of cation exchange during sample processing, all XAD and RO samples contained substantial metal concentrations. AsFlFFF fractograms allowed metal distributions to be characterized as a function of DOM component molecular weight (MW). In SR RFSW, Fe, Al, and Cu were primarily associated with intermediate to higher than average MW DOM components. SR RO, XAD-8, and XAD-4 samples from May 2012 showed similar MW trends for Fe and Al but Cu tended to associate more with lower MW DOM. LF DOM had abundant Cu and Zn, perhaps due to amine groups that should be present due to its primarily algal origins. None of the fractograms showed obvious evidence for mineral nanoparticles, although some very small mineral nanoparticles might have been present at trace concentrations. This research suggests that AsFlFFF is important for understanding how metals are distributed in different DOM samples (including IHSS samples), which may be key to metal reactivity and bioavailability.

  11. Influence of Flue Gas Desulfurization Gypsum Amendments on Heavy Metal Distribution in Reclaimed Sodic Soils

    PubMed Central

    Chen, Qun; Wang, Shujuan; Li, Yan; Zhang, Ning; Zhao, Bo; Zhuo, Yuqun; Chen, Changhe

    2015-01-01

    Abstract Although flue gas desulfurization (FGD) gypsum has become an effective soil amendment for sodic soil reclamation, it carries extra heavy metal contamination into the soil environment. The fate of heavy metals introduced by FGD gypsum in sodic or saline–alkali soils is still unclear. This work aims to investigate the effects of FGD gypsum addition on the heavy metal distributions in a sodic soil. Original soil samples were collected from typical sodic land in north China. Soil column leaching tests were conducted to investigate the influence of FGD gypsum addition on the soil properties, especially on distribution profiles of the heavy metals (Pb, Cd, Cr, As, and Hg) in the soil layers. Results showed that pH, electrical conductivity, and exchangeable sodium percentage in amended soils were significantly reduced from 10.2 to 8.46, 1.8 to 0.2 dS/m, and 18.14% to 1.28%, respectively. As and Hg concentrations in the soils were found to be positively correlated with FGD gypsum added. The amount of Hg in the leachate was positively correlated with FGD gypsum application ratio, whereas a negative correlation was observed between the Pb concentration in the leachate and the FGD gypsum ratio. Results revealed that heavy metal concentrations in soils complied well with Environmental Quality Standard for Soils in China (GB15618-1995). This work helps to understand the fate of FGD gypsum-introduced heavy metals in sodic soils and provides a baseline for further environmental risk assessment associated with applying FGD gypsum for sodic soil remediation. PMID:26064038

  12. Use of Synchrotron X-ray Fluorescence to Measure Trace Metal Distribution in the Brain

    NASA Astrophysics Data System (ADS)

    Linkous, D.; Flinn, J. M.; Lanzirotti, A.; Frederickson, C.; Jones, B. F.; Bertsch, P. M.

    2002-12-01

    X26A, National Synchrotron Light Source, was used to quantitatively evaluate the spatial distribution of trace metals, such as Zn and Cu, in brain tissue. X-ray microprobe techniques offer distinct advantages over other analytical methods by allowing analyses to be done in-situ with little or no chemical pretreatment and low detection limits (about 1 ppm). In the context of neuroscience, SXRF can provide non-destructive measurements of specific metal concentrations and distribution within nerve (brain) tissue. Neuronal tissue from organisms having undergone different normal or experimental conditions may be compared, with analytical capacities not limited by binding states of the metal (i.e., vesicular or enzymatic), as is the case with staining techniques.. Whole regions of tissue may be scanned for detectable trace metals at spatial resolutions of 10um or less using focused monochromatic x-ray beams. Here special attention has been given to zinc because it is the most common trace metal in the brain, and levels have been increasing in the environment. In this investigation, zinc concentrations present within the hilus of a rat hippocampus, and to a lesser extent in the cortex, have been shown to increase following long-term ingestion of zinc-enhanced drinking water that was associated with deficits in spatial memory. Concomitantly, copper concentrations in the internal capsule were comparatively lower. Other first order transition metals, Cr, V, Mn, and Co were not detected. In contrast, elevated levels of Zn, Cu, and Fe have been seen in amyloid plaques associated with Alzheimer's disease.

  13. Transformation rules and degradation of CAHs by Fentonlike oxidation in growth ring of water distribution network-A review

    NASA Astrophysics Data System (ADS)

    Zhong, D.; Ma, W. C.; Jiang, X. Q.; Yuan, Y. X.; Yuan, Y.; Wang, Z. Q.; Fang, T. T.; Huang, W. Y.

    2017-08-01

    Chlorinated hydrocarbons are widely used as organic solvent and chemical raw materials. After treatment, water polluted with trichloroethylene (TCE)/tetrachloroethylene (PCE) can reach the water quality requirements, while water with trace amounts of TCE/PCE is still harmful to humans, which will cause cancers. Water distribution network is an extremely complicated system, in which adsorption, desorption, flocculation, movement, transformation and reduction will occur, leading to changes of TCE/PCE concentrations and products. Therefore, it is important to investigate the transformation rules of TCE/PCE in water distribution network. What’s more, growth-ring, including drinking water pipes deposits, can act as catalysts in Fenton-like reagent (H2O2). This review summarizes the status of transformation rules of CAHs in water distribution network. It also evaluates the effectiveness and fruit of CAHs degradation by Fenton-like reagent based on growth-ring. This review is important in solving the potential safety problems caused by TCE/PCE in water distribution network.

  14. Bond-length distributions for ions bonded to oxygen: alkali and alkaline-earth metals

    PubMed Central

    Gagné, Olivier Charles; Hawthorne, Frank Christopher

    2016-01-01

    Bond-length distributions have been examined for 55 configurations of alkali-metal ions and 29 configurations of alkaline-earth-metal ions bonded to oxygen, for 4859 coordination polyhedra and 38 594 bond distances (alkali metals), and for 3038 coordination polyhedra and 24 487 bond distances (alkaline-earth metals). Bond lengths generally show a positively skewed Gaussian distribution that originates from the variation in Born repulsion and Coulomb attraction as a function of interatomic distance. The skewness and kurtosis of these distributions generally decrease with increasing coordination number of the central cation, a result of decreasing Born repulsion with increasing coordination number. We confirm the following minimum coordination numbers: [3]Li+, [3]Na+, [4]K+, [4]Rb+, [6]Cs+, [3]Be2+, [4]Mg2+, [6]Ca2+, [6]Sr2+ and [6]Ba2+, but note that some reported examples are the result of extensive dynamic and/or positional short-range disorder and are not ordered arrangements. Some distributions of bond lengths are distinctly multi-modal. This is commonly due to the occurrence of large numbers of structure refinements of a particular structure type in which a particular cation is always present, leading to an over-representation of a specific range of bond lengths. Outliers in the distributions of mean bond lengths are often associated with anomalous values of atomic displacement of the constituent cations and/or anions. For a sample of [6]Na+, the ratio U eq(Na)/U eq(bonded anions) is partially correlated with 〈[6]Na+—O2−〉 (R 2 = 0.57), suggesting that the mean bond length is correlated with vibrational/displacement characteristics of the constituent ions for a fixed coordination number. Mean bond lengths also show a weak correlation with bond-length distortion from the mean value in general, although some coordination numbers show the widest variation in mean bond length for zero distortion, e.g. Li+ in [4]- and [6]-coordination, Na+ in [4]- and [6

  15. Bond-length distributions for ions bonded to oxygen: alkali and alkaline-earth metals.

    PubMed

    Gagné, Olivier Charles; Hawthorne, Frank Christopher

    2016-08-01

    Bond-length distributions have been examined for 55 configurations of alkali-metal ions and 29 configurations of alkaline-earth-metal ions bonded to oxygen, for 4859 coordination polyhedra and 38 594 bond distances (alkali metals), and for 3038 coordination polyhedra and 24 487 bond distances (alkaline-earth metals). Bond lengths generally show a positively skewed Gaussian distribution that originates from the variation in Born repulsion and Coulomb attraction as a function of interatomic distance. The skewness and kurtosis of these distributions generally decrease with increasing coordination number of the central cation, a result of decreasing Born repulsion with increasing coordination number. We confirm the following minimum coordination numbers: ([3])Li(+), ([3])Na(+), ([4])K(+), ([4])Rb(+), ([6])Cs(+), ([3])Be(2+), ([4])Mg(2+), ([6])Ca(2+), ([6])Sr(2+) and ([6])Ba(2+), but note that some reported examples are the result of extensive dynamic and/or positional short-range disorder and are not ordered arrangements. Some distributions of bond lengths are distinctly multi-modal. This is commonly due to the occurrence of large numbers of structure refinements of a particular structure type in which a particular cation is always present, leading to an over-representation of a specific range of bond lengths. Outliers in the distributions of mean bond lengths are often associated with anomalous values of atomic displacement of the constituent cations and/or anions. For a sample of ([6])Na(+), the ratio Ueq(Na)/Ueq(bonded anions) is partially correlated with 〈([6])Na(+)-O(2-)〉 (R(2) = 0.57), suggesting that the mean bond length is correlated with vibrational/displacement characteristics of the constituent ions for a fixed coordination number. Mean bond lengths also show a weak correlation with bond-length distortion from the mean value in general, although some coordination numbers show the widest variation in mean bond length for zero distortion, e.g. Li(+) in

  16. Stress-driven crystallization via shear-diffusion transformations in a metallic glass at very low temperatures

    NASA Astrophysics Data System (ADS)

    Mao, Yunwei; Li, Ju; Lo, Yu-Chieh; Qian, Xiaofeng; Ma, Evan

    2015-06-01

    At elevated temperatures, glasses crystallize via thermally activated diffusion. However, metallic glasses can also undergo deformation-induced crystallization at very low temperatures. Here we demonstrate the crystallization of A l50F e50 metallic glasses under cyclic deformation at 50 K using molecular dynamics simulations and reveal the underlying atomic-scale processes. We demonstrate that stress-driven nonaffine atomic rearrangements, or shear diffusion transformation (SDT) events, lead to successive metabasin-to-metabasin transitions and long-range ordering. We also illustrate that the nucleation and growth of the crystal proceed via collective attachment of ordered clusters, advancing the amorphous/crystal interface in an intermittent manner. The cooperative nature of the steplike crystallization is attributed to the large activation volume of Eshelby transformations which generate as a by-product nonaffine diffusive atomic displacements that accumulate over loading cycles. The dual nature of shear (affine) and diffusion (nonaffine) in low-temperature stress-driven SDT events thus unifies inelasticity with crystallization.

  17. Metal-mediated oxidation of fluoroquinolone antibiotics in water: A review on kinetics, transformation products, and toxicity assessment.

    PubMed

    Feng, Mingbao; Wang, Zunyao; Dionysiou, Dionysios D; Sharma, Virender K

    2017-08-30

    Fluoroquinolones (FQs) are among the most potent antimicrobial agents, which have seen their increasing use as human and veterinary medicines to control bacterial infections. FQs have been extensively found in surface water and municipal wastewaters, which has raised great concerns due to their negative impacts to humans and ecological health. It is of utmost importance that FQs are treated before their release into the environment. This paper reviews oxidative removal of FQs using reactive oxygen (O3 and OH), sulfate radicals (SO4(-)), and high-valent transition metal (Mn(VII) and Fe(VI)) species. The role of metals in enhancing the performance of reactive oxygen and sulfur species is presented. The catalysts can significantly enhance the production of OH and/or SO4(-) radicals. At neutral pH, the second-order rate constants (k, M(-1)s(-1)) of the reactions between FQs and oxidants follow the order as k(OH)>k(O3)>k(Fe(VI))>k(Mn(VII)). Moieties involved to transform target FQs to oxidized products and participation of the catalysts in the reaction pathways are discussed. Generally, the piperazinyl ring of FQs was found as the preferential attack site by each oxidant. Meanwhile, evaluation of aquatic ecotoxicity of the transformation products of FQs by these treatments is summarized. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. On the Metallicity Distribution of the Peculiar Globular Cluster M22

    NASA Astrophysics Data System (ADS)

    Lee, Jae-Woo

    2016-10-01

    In our previous study, we showed that the peculiar globular cluster (GC) M22 contains two distinct stellar populations, namely the Ca-w and Ca-s groups, which have different physical properties, chemical compositions, spatial distributions, and kinematics. We proposed that M22 was most likely formed via a merger of two GCs with heterogeneous metallicities in a dwarf galaxy environment and then later accreted to our Galaxy. In their recent study, Mucciarelli et al. claimed that M22 is a normal monometallic globular cluster without any perceptible metallicity spread among the two groups of stars, which challenges our results and those of others. We devise new strategies for the local thermodynamic equilibrium abundance analysis of red giant branch stars in GCs and show that there exists a spread in the iron abundance distribution in M22.

  19. Spatio-Temporal Distributions of Particulate Matter and Heavy Metal Exposures in Washington, DC

    NASA Astrophysics Data System (ADS)

    Greene, N. A.; Morris, V. R.

    2005-05-01

    The District of Columbia ranks seventh highest as one of the unhealthiest places to live due to poor air quality (EPA Report, 1999). Particulate matter is one of the major contributors to pollution in the Washington, DC environment. Quite often ambient airborne toxics are closely associated with particulate matter. Fine aerosols are characterized as particles with diameters smaller than 1m and are easily deposited into the alveolar regions of the human lungs, which can impose severe health risks. In this study, high-resolution aerosol measurements of PM2.5 and heavy metals like chromium, lead, cadmium and arsenic, in four wards of Washington, DC have been performed. Spatial distributions of both aerosols and heavy metals are characterized as a function of size and mass properties. This paper presents results of the spatial analysis of aerosol number and mass distribution for PM2.5.

  20. Heavy Metal Distribution in Opportunistic Beach Nourishment: A Case Study in Greece

    PubMed Central

    Kallithrakas-Kontos, Nikolaos G.; Synolakis, Costas

    2013-01-01

    The existence and distribution of persistent pollutants, such as heavy metals, in coastal sediment used for opportunistic beach nourishment, is a problem that has not received much attention. Here, we assessed the coastal sediments in one restoration project for the occurrence and distribution of heavy metals, by utilizing an Energy Dispersive X-Ray Fluorescence (EDXRF) system. Heavy metal point sources included (i) the effluents of small industries (tanneries), (ii) wastewater treatment plant effluents, and (iii) paint and oil scraps from substandard ship maintenance activities that take place on ports breakwaters. A few neighboring beaches were found to have similar heavy metal concentrations, with mean values of Cu, Zn, and Pb ranging from 80 to 130, 15 to 25, and 25 to 40 mg/kg, respectively. Existing legislation regarding dredging activities in Greece appears insufficient for sustainable and environmentally friendly nourishment. We conclude that before opportunistic beach restoration projects materialize with material borrowed from ports and harbors the quality of the dredged material needs to be assessed. PMID:24379742

  1. A novel fractionation approach for water constituents – distribution of storm event metals

    PubMed Central

    McKenzie, Erica R.; Young, Thomas M.

    2014-01-01

    A novel fractionation method, based on both particle size and settling characteristics, was employed to examine metal distributions among five fractions. In-stream and stormwater runoff samples were collected from four land use types: highway, urban, agricultural (storm event and irrigation), and natural. Highway samples contained the highest dissolved concentrations for most metals, and freshwater ambient water quality criteria were exceeded for Cd, Cu, Pb, and Zn in the first storm of the water year. Anthropogenic sources were indicated for Cu, Zn, Cd, and Pb in highway and urban samples, and total metal loadings (mg/km2) were observed to be as follows: highway > urban > agricultural storm event ~ natural > agricultural irrigation. Notably, ~10-fold higher suspended solids concentration was observed in the agricultural storm event sample, and suspended solids-associated metals were correspondingly elevated. Distribution coefficients revealed the following affinities: Zn, Ni, Cd, and Pb to large dense particles; and Cu, Zn, Cr, Ni, and Pb to colloidal organic matter. PMID:23535891

  2. Effects of rare earth elements on the distribution of mineral elements and heavy metals in horseradish.

    PubMed

    Wang, Lihong; Huang, Xiaohua; Zhou, Qing

    2008-09-01

    In order to investigate the effects of rare earth elements (REEs) on horseradish, the distribution of the mineral elements and heavy metals in different organs of horseradish have been studied by using inductively coupled plasma-atomic emission spectrometry (ICP-AES). Meanwhile, three variable major parameters, namely the concentration of REEs, the type of REEs, and the growth stage of plant were chosen. The results indicated that the test REEs, Ce(III) and Tb(III), could be accumulated in leaves, stems and roots of horseradish. In addition, we found that the content of mineral elements was increased in horseradish treated with 20mgl(-1) of Ce(III), but not those with the 20mgl(-1) of Tb(III). Moreover, the content of mineral elements in horseradish was decreased with the increasing concentration of REEs (100, 300mgl(-1)). Furthermore, we found that there were the opposite effects on the content of the heavy metals in horseradish treated with REEs. Finally, we found that the effect of REEs on the accumulation of REEs, and the content of mineral elements or heavy metals of horseradish during vigorous growth stage, no matter positive or negative, was more obvious than that of the other growth stages. These results demonstrated that the distribution behaviors of mineral elements and heavy metals in horseradish can be affected by the type and concentration of REEs, and the growth period of plant.

  3. Heavy metal distribution in opportunistic beach nourishment: a case study in Greece.

    PubMed

    Foteinis, Spyros; Kallithrakas-Kontos, Nikolaos G; Synolakis, Costas

    2013-01-01

    The existence and distribution of persistent pollutants, such as heavy metals, in coastal sediment used for opportunistic beach nourishment, is a problem that has not received much attention. Here, we assessed the coastal sediments in one restoration project for the occurrence and distribution of heavy metals, by utilizing an Energy Dispersive X-Ray Fluorescence (EDXRF) system. Heavy metal point sources included (i) the effluents of small industries (tanneries), (ii) wastewater treatment plant effluents, and (iii) paint and oil scraps from substandard ship maintenance activities that take place on ports breakwaters. A few neighboring beaches were found to have similar heavy metal concentrations, with mean values of Cu, Zn, and Pb ranging from 80 to 130, 15 to 25, and 25 to 40 mg/kg, respectively. Existing legislation regarding dredging activities in Greece appears insufficient for sustainable and environmentally friendly nourishment. We conclude that before opportunistic beach restoration projects materialize with material borrowed from ports and harbors the quality of the dredged material needs to be assessed.

  4. Distribution of heavy metals around the Barakah nuclear power plant in the United Arab Emirates.

    PubMed

    Al Rashdi, Mouza Rashid; Alaabed, Sulaiman; El Tokhi, Mohamed; Howari, Fares M; El Mowafi, Walid; Arabi, Alya A

    2017-07-07

    Inductively coupled plasma emission spectroscopy was used to measure the concentrations of heavy metals in 58 samples collected from the Barakah nuclear power plant (BNPP) area, UAE. The grain size distribution was symmetric, but the samples ranged from fine to coarse sand. The inverse relationship between grain size and heavy metal contaminations was validated. The pre-operational average heavy metal contaminations around the BNPP were 0.03, 0.40, 1.2, 2.05, 1.66, 1.6, 5.9, 7.3, 7, 8.8, 60, and 2521 ppm for Cd, Mo, Co, Cu, Pb, As, Zn, Ni, V, Cr, Mn, and Fe, respectively. The spatial distribution was more compact in the south compared to the north, with less severe contaminations in the east and west. The negative geoaccumulation indices suggest an uncontaminated area, and the BNPP has minor enrichments. All concentrations were significantly below the safe limits set by the Dutch guidelines. The levels of heavy metals reported in the UAE were lower than levels reported in countries around the world.

  5. Spatial distribution and toxicity assessment of heavy metals in sediments of Liaohe River, northeast China.

    PubMed

    He, Yan; Meng, Wei; Xu, Jian; Zhang, Yuan; Liu, Sisi; Guo, Changsheng

    2015-10-01

    Twenty-four surface sediment samples were collected from Liaohe River in June 2014 for the analysis of total concentrations of Cu, Pb, Zn, Cd, Ni, Fe, and Mn. The spatial distribution of heavy metals in Liaohe River was site specific, with Hun River as the most polluted river mainly affected by industrial and human activities. The contents of acid-volatile sulfide (AVS) and simultaneously extracted metals (SEMs) in Liaohe River varied significantly, ranging from 0.03 to 19.4 μmol/g and 0.14 to 10.8 μmol/g, respectively. Sulfate-reducing bacteria (SRB) community size, organic matter and sulfate availability, and sediment redox status may be the main factors affecting the AVS distribution. Among all the acid-extracted metals, Zn was dominant in all samples, whereas much more toxic Cd contributed less than 1.0 % to the total SEMs. Sediment quality guidelines (SQGs) and AVS-SEM models were used to predict the sediment toxicity. Results revealed that only a small portion of sites exhibited potential metal toxicity to aquatic biota, while adverse effects should rarely occur in majority of sites. Comparison of the two assessment methods showed inconsistent results, indicating that each method had its own limitations. The combination of different methods will be more convincing as to the sediment quality assessment.

  6. THE RADIAL METALLICITY GRADIENTS IN THE MILKY WAY THICK DISK AS FOSSIL SIGNATURES OF A PRIMORDIAL CHEMICAL DISTRIBUTION

    SciTech Connect

    Curir, A.; Serra, A. L.; Spagna, A.; Lattanzi, M. G.; Re Fiorentin, P.; Diaferio, A.

    2014-04-01

    In this Letter we examine the evolution of the radial metallicity gradient induced by secular processes, in the disk of an N-body Milky Way-like galaxy. We assign a [Fe/H] value to each particle of the simulation according to an initial, cosmologically motivated, radial chemical distribution and let the disk dynamically evolve for ∼6 Gyr. This direct approach allows us to take into account only the effects of dynamical evolution and to gauge how and to what extent they affect the initial chemical conditions. The initial [Fe/H] distribution increases with R in the inner disk up to R ≈ 10 kpc and decreases for larger R. We find that the initial chemical profile does not undergo major transformations after ∼6 Gyr of dynamical evolution. The final radial chemical gradients predicted by the model in the solar neighborhood are positive and of the same order as those recently observed in the Milky Way thick disk. We conclude that (1) the spatial chemical imprint at the time of disk formation is not washed out by secular dynamical processes and (2) the observed radial gradient may be the dynamical relic of a thick disk originated from a stellar population showing a positive chemical radial gradient in the inner regions.

  7. Leaching behavior of heavy metals and transformation of their speciation in polluted soil receiving simulated acid rain.

    PubMed

    Zheng, Shun-an; Zheng, Xiangqun; Chen, Chun

    2012-01-01

    Heavy metals that leach from contaminated soils under acid rain are of increasing concern. In this study, simulated acid rain (SAR) was pumped through columns of artificially contaminated purple soil. Column leaching tests and sequential extraction were conducted for the heavy metals Cu, Pb, Cd, and Zn to determine the extent of their leaching as well as to examine the transformation of their speciation in the artificially contaminated soil columns. Results showed that the maximum leachate concentrations of Cu, Pb, Cd, and Zn were less than those specified in the Chinese Quality Standards for Groundwater (Grade IV), thereby suggesting that the heavy metals that leached from the polluted purple soil receiving acid rain may not pose as risks to water quality. Most of the Pb and Cd leachate concentrations were below their detection limits. By contrast, higher Cu and Zn leachate concentrations were found because they were released by the soil in larger amounts as compared with those of Pb and Cd. The differences in the Cu and Zn leachate concentrations between the controls (SAR at pH 5.6) and the treatments (SAR at pH 3.0 and 4.5) were significant. Similar trends were observed in the total leached amounts of Cu and Zn. The proportions of Cu, Pb, Cd, and Zn in the EXC and OX fractions were generally increased after the leaching experiment at three pH levels, whereas those of the RES, OM, and CAR fractions were slightly decreased. Acid rain favors the leaching of heavy metals from the contaminated purple soil and makes the heavy metal fractions become more labile. Moreover, a pH decrease from 5.6 to 3.0 significantly enhanced such effects.

  8. Leaching Behavior of Heavy Metals and Transformation of Their Speciation in Polluted Soil Receiving Simulated Acid Rain

    PubMed Central

    Zheng, Shun-an; Zheng, Xiangqun; Chen, Chun

    2012-01-01

    Heavy metals that leach from contaminated soils under acid rain are of increasing concern. In this study, simulated acid rain (SAR) was pumped through columns of artificially contaminated purple soil. Column leaching tests and sequential extraction were conducted for the heavy metals Cu, Pb, Cd, and Zn to determine the extent of their leaching as well as to examine the transformation of their speciation in the artificially contaminated soil columns. Results showed that the maximum leachate concentrations of Cu, Pb, Cd, and Zn were less than those specified in the Chinese Quality Standards for Groundwater (Grade IV), thereby suggesting that the heavy metals that leached from the polluted purple soil receiving acid rain may not pose as risks to water quality. Most of the Pb and Cd leachate concentrations were below their detection limits. By contrast, higher Cu and Zn leachate concentrations were found because they were released by the soil in larger amounts as compared with those of Pb and Cd. The differences in the Cu and Zn leachate concentrations between the controls (SAR at pH 5.6) and the treatments (SAR at pH 3.0 and 4.5) were significant. Similar trends were observed in the total leached amounts of Cu and Zn. The proportions of Cu, Pb, Cd, and Zn in the EXC and OX fractions were generally increased after the leaching experiment at three pH levels, whereas those of the RES, OM, and CAR fractions were slightly decreased. Acid rain favors the leaching of heavy metals from the contaminated purple soil and makes the heavy metal fractions become more labile. Moreover, a pH decrease from 5.6 to 3.0 significantly enhanced such effects. PMID:23185399

  9. Ductility of metal alloys with grain size distribution in a wide range of strain rates

    NASA Astrophysics Data System (ADS)

    Skripnyak, Vladimir V.; Skripnyak, Nataliya V.; Skripnyak, Evgeniya G.

    Ductility of ultrafine grained (UFG) metal alloys with a distribution of grain size was investigated in wide loading conditions by numerical simulation. The multiscale models with a unimodal and a bimodal grain size distributions were developed using the data of structure research of hexagonal close packed and face center cubic UFG alloys. Macroscopic fracture is considered as a result of the formation of percolation clusters of damage at the mesoscopic level. The critical fracture strain of UFG alloys on the mesoscale level depends on the relative volumes of coarse grains. The nucleation of damages at quasi-static and dynamic loading is associated with strain localization in UFG partial volumes with bimodal grain size distribution. The concentration of damages arise in the vicinity of the boundaries of coarse and ultrafine grains. The occurrence of a bimodal grain size distributions causes the increase of UFG alloys' ductility, but decrease of their tensile strength. Linkoping University, Sweden.

  10. Distribution and bioaccumulation of heavy metals in marine organisms in east and west Guangdong coastal regions, South China.

    PubMed

    Zhang, Ling; Shi, Zhen; Jiang, Zhijian; Zhang, Jingping; Wang, Fei; Huang, Xiaoping

    2015-12-30

    Heavy metal (Cu, Pb, Zn, Cr, Cd, As) concentrations, distribution and bioaccumulation were studied in marine organisms in Guangdong coastal regions. Heavy metal concentrations and distribution in organisms showed characteristics according to areas and species. Heavy metal concentrations in most organisms were higher in west than in east, tightly related to the local industry structure and the disequilibrium of metal discharge. Generally, high heavy metal concentrations were detected in molluscs and low concentrations were detected in fish. Bioaccumulation factor was used to assess the accumulation level of marine organisms to heavy metals, of which Cd, Cu and As were the most accumulated elements. Accumulation abilities to heavy metals varied among organism species, such as Distorsio reticulate accumulating Cu, Zn, Cd, As, Loligo beka Sasaki accumulating Pb, Cu, Cr, and Turritella bacillum Kiener accumulating Zn, Cd, As. By comparison, Johnius belengeri, Argyrosomus argentatus, Cynoglossus sinicus Wu had relatively low accumulation abilities.

  11. Radial Distribution of Martensitic Phase Transformation in a Metastable Stainless Steel under Torsional Deformation: A Synchrotron X-ray Diffraction Study

    SciTech Connect

    Cakmak, Ercan; Choo, Hahn; An, Ke; Ren, Yang

    2011-01-01

    The strain-induced martensitic phase transformation in a metastable 304 L stainless steel under torsional deformation was investigated using synchrotron X-ray diffraction. The measured radial distribution of the martensite phase fraction in a solid cylindrical specimen agrees well with the prediction based on a combination of transformation kinetics and a radial plastic strain distribution equation.

  12. Impact of defectiveness on the parameters of the acoustoelectric transformations in heterogeneous non-metallic materials

    NASA Astrophysics Data System (ADS)

    Fursa, T. V.; Lyukshin, B. A.; Utsyn, G. E.; Dann, D. D.

    2015-04-01

    The article studies acoustoelectric transformations of concrete with a crack. The research presents three-dimensional modeling and 3D visualization of wave processes in a concrete sample with a surface crack. The parameters of the electrical response are found to reflect the processes of interaction between the acoustic wave front and the defect and boundaries of the sample.

  13. [Analysis of heavy metals distribution characteristics and pollution assessment in agricultural region soils of Huaihe basin].

    PubMed

    Xiao, Xue; Zhao, Nan-Jing; Yuan, Jing; Ma, Ming-Jun; Fang, Li; Wang, Yin; Meng, De-Shuo; Yu, Yang; Tang, Jie; Zhang, Xiao-Ling; Dai, Yuan; Zhang, Yu-Jun; Liu, Jian-Guo; Liu, Wen-Qing

    2014-07-01

    By means of field sampling and laboratory analysis, the content distribution characteristics of Cd, Cr, Cu, Ni, Pb and Zn in agricultural region soils of Huaihe basin in Anhui province were analyzed. Assessment of heavy metal pollutions was conducted using enrichment factor, geoaccumulation index and potential ecological risk index. The results showed that the average mass fraction of Cd and Cu was 0.113 5 and 22.09 mg x kg(-1) respectively in the study area soil, which were above the background values 0.097 and 20.4 mg x kg(-1) in Anhui Province. The average mass fraction of other four heavy metals did not exceed the average values of Anhui Province. The results of the evaluations from geoaccumulation index and ecological risk assessment discovered that Cd is the strongest pollution metal among six heavy metals in the study area soil. For some samples of the study soil, Cd was slight risk for the ecosystem. The ecosystem risks caused by the other five heavy metals were not obviously for the sampling points. The entire study area soils were mid integrated potential ecological risk.

  14. Spatial distribution and ecological risk assessment of metals in sediments of Baiyangdian wetland ecosystem.

    PubMed

    Su, Liya; Liu, Jingling; Christensen, Per

    2011-07-01

    Although there are many studies of heavy metal contaminations of sediments, attention has seldom been paid to the problem in developing countries. The purpose of this article is to find the distribution and ecological risk of As, Hg, Cr, Cd, Pb, Cu, and Zn in surface sediment of Baiyangdian which is the biggest wetland in Northeast China. We apply three methodologies. The first is literature analysis comparing total concentrations of heavy metals with other water bodies around world. The second is Chinese Environmental Quality Standard for Soils (EQSS), National Environmental Protection Agency of China 1995, and the third is Soil and Aquatic Sediment Guidelines and Standards issued by New York Department of Environmental Conservation (NYSDEC). The results show that compared to other water bodies around the world, the seven heavy metals are low. However, Cd was found in the most polluting level of EQSS near a village and was second grade some distance from it. The village was also the most polluted site of Zn, which was in the second grade. When assessed by NYSDEC, Cu, Cr, and As contaminated the sediment and with moderate impacts on benthic life while Pb, Hg, and Zn were found at tolerable levels throughout Baiyangdian. The centre of Cu and Cr contamination was also near the village. As is the most polluting heavy metals with a major occurrence in the middle of the wetland. There were no heavy metals creating severe disturbance to the benthic communities. Based on the assessment, this article proposes different options for more sustainable management.

  15. The spatial and temporal distribution of heavy metals in sediments of Victoria Harbour, Hong Kong.

    PubMed

    Tang, Chloe Wing-Yee; Ip, Carman Ching-Man; Zhang, Gan; Shin, Paul K S; Qian, Pei-Yuan; Li, Xiang-Dong

    2008-01-01

    Victoria Harbour has received substantial loadings of pollutants from industrial and municipal wastewater discharged since the 1950s. Inputs of contaminants have declined dramatically during the last two decades as a result of better controls at the source and improved wastewater treatment facilities. To assess the spatial and temporal changes of metal contaminants in sediments in Victoria Harbour, core and grab sediments were collected. The central harbour areas were generally contaminated with heavy metals. The spatial distribution of trace metals can probably be attributed to the proximity of major urban and industrial discharge points, and to the effect of tidal flushing in the harbour. In the sediment cores, the highest concentrations of trace metals were observed to have accumulated during the 1950s-1980s, corresponding with the period of rapid urban and industrial development in Hong Kong. From the late 1980s, there has been a major decline in the concentrations of trace metals, due to a reduction in industrial activities and to the enactment of wastewater pollution controls in the territory. The Pb isotopic compositions of the sediments revealed the anthropogenic inputs of Pb to the harbour. The (206)Pb/(207)Pb ratios varied from 1.154 to 1.190, which were lower than those of background geological materials in Hong Kong ((206)Pb/(207)Pb: 1.201-1.279). The data also indicated that the Pb in the harbour sediments most likely originated from mixed sources, including the leaded gasoline used in the past and other anthropogenic sources.

  16. A comprehensive study of metal distribution in three main classes of seaweed.

    PubMed

    Ryan, Siobhan; McLoughlin, Peter; O'Donovan, Orla

    2012-08-01

    This paper provides one of the most comprehensive studies of metal distributions in three main macroalgae species. In this novel study, levels of total, intracellular and surface bound Pb, Zn, As, Cd, Co, Cr, Cu, Mn and Ni associated with Polysiphonia lanosa (L) Tandy, Ascophyllum nodosum (L) Le Jolis, Fucus vesiculosus (L) and Ulva sp. were determined. Additionally, water and sediment metal levels were analysed to gain an insight into the relative uptake efficiencies of different macroalgal species. Samples were collected from a clean site in Fethard-on-Sea, Wexford, Ireland (52°11'53.68'N, 6°49'34.64'W), in May 2008. Results demonstrated that total, intracellular and surface bound metal levels varied according to metal and seaweed species, with the highest proportion of metals found to be intracellular. Inhibition of Mn uptake by Zn was indicated for P. lanosa. Furthermore, P. lanosa had enhanced bioaccumulation ability, with the highest Concentration Factor reported of any seaweed to date. Copyright © 2012 Elsevier Ltd. All rights reserved.

  17. Distribution of heavy metals and environmental assessment of surface sediment of typical estuaries in eastern China.

    PubMed

    Bi, Shipu; Yang, Yuan; Xu, Chengfen; Zhang, Yong; Zhang, Xiaobo; Zhang, Xianrong

    2017-08-15

    Estuary sediment is a major pollutant enrichment medium and is an important biological habitat. This sediment has attracted the attention of the marine environmental scientists because it is a more stable and effective medium than water for monitoring regional environmental quality conditions and trends. Based on a large amount of measurement data, we analyzed the concentrations, distribution, and sources of seven heavy metals (As, Cd, Cr, Cu, Hg, Pb, and Zn) in the surface sediment of typical estuaries that empty into the sea in eastern China: the Liaohe River Estuary, Yellow River Estuary, Yangtze River Estuary, Minjiang River Estuary, and Pearl River Estuary. The heavy metal concentrations in the sediments vary considerably from one estuary to the next. The Liaohe River Estuary sediment contains elevated levels of Cd, Hg, and Zn. The Yellow River Estuary sediment contains elevated levels of As. The sediments in the Yangtze River and Minjiang River estuaries contain elevated levels of Cd and Cu and of Pb and Zn, respectively. The sediment in the Pearl River Estuary contains elevated levels of all seven heavy metals. We used the Nemerow index method to assess the environment quality. The heavy metal pollution in the Liaohe River and Pearl River estuaries is more severe than that in the other estuaries. Additional work indicates that the heavy metal pollution in the Liaohe River and Pearl River estuaries is caused mainly by human activity. Copyright © 2017. Published by Elsevier Ltd.

  18. Imprints of Radial Migration on the Milky Way’s Metallicity Distribution Functions

    NASA Astrophysics Data System (ADS)

    Loebman, Sarah R.; Debattista, Victor P.; Nidever, David L.; Hayden, Michael R.; Holtzman, Jon A.; Clarke, Adam J.; Roškar, Rok; Valluri, Monica

    2016-02-01

    Recent analysis of the SDSS-III/Apache Point Observatory Galactic Evolution Experiment (APOGEE) Data Release 12 stellar catalog has revealed that the Milky Way’s (MW) metallicity distribution function (MDF) changes shape as a function of radius, transitioning from being negatively skewed at small Galactocentric radii to positively skewed at large Galactocentric radii. Using a high-resolution, N-body+SPH simulation, we show that the changing skewness arises from radial migration—metal-rich stars form in the inner disk and subsequently migrate to the metal-poorer outer disk. These migrated stars represent a large fraction (\\gt 50%) of the stars in the outer disk; they populate the high-metallicity tail of the MDFs and are, in general, more metal-rich than the surrounding outer disk gas. The simulation also reproduces another surprising APOGEE result: the spatially invariant high-[α/Fe] MDFs. This arises in the simulation from the migration of a population formed within a narrow range of radii (3.2 ±1.2 kpc) and time (8.8 ± 0.6 Gyr ago), rather than from spatially extended star formation in a homogeneous medium at early times. These results point toward the crucial role radial migration has played in shaping our MW.

  19. [Heavy metals distribution characteristics and risk assessment of water below an electroplating factory].

    PubMed

    Hang, Xiao-Shuai; Wang, Huo-Yan; Zhou, Jian-Min

    2008-10-01

    Surface water and shallow groundwater within the flow of an electroplating factory was analyzed in order to study the resulting impact. The analysis method of ICP-AES was used to analyze content of zinc, manganese, chromium, copper and nickel in surface water and groundwater samples. The results indicate acidic pollutants of zinc, manganese, chromium, copper and nickel were discharged from the factory with concentrations of 1.34, 3.77, 28.1, 6.40 and 9.37 mg x L(-1), respectively; and pH was 2.32. They all exceeded permissible levels according to Integrated Wastewater Discharge Standard except zinc. Factory discharge is responsible for the longitudinal distribution characteristics of heavy metals in the stream water downstream from the factory. Heavy metals variations in the well water do not suggest they were affected by heavy metals in the stream, indicating that the migration rates of heavy metals in soils were relatively low. Risk assessment shows surface water quality significantly deteriorated. Nickel and manganese in the stream water exceeded the standard levels seriously, and chromium and copper in some samples were also above Grade III standard levels according to Environmental Quality Standard for Surface Water. Moreover, all studied heavy metals in 14 groundwater samples measured within drinking water standard, except manganese in 4 groundwater samples, which were Grade IV according to Quality Standard for Ground water.

  20. Revealing β-relaxation mechanism based on energy distribution of flow units in metallic glass

    NASA Astrophysics Data System (ADS)

    Lu, Z.; Shang, B. S.; Sun, Y. T.; Zhu, Z. G.; Guan, P. F.; Wang, W. H.; Bai, H. Y.

    2016-04-01

    The β-relaxation, which is the source of the dynamics in glass state and has practical significance to relaxation and mechanical properties of glasses, has been an open question for decades. Here, we propose a flow unit perspective to explain the structural origin and evolution of β-relaxation based on experimentally obtained energy distribution of flow units using stress relaxation method under isothermal and linear heating modes. Through the molecular dynamics simulations, we creatively design various artificial metallic glass systems and build a direct relation between β-relaxation behavior and features of flow units. Our results demonstrate that the β-relaxation in metallic glasses originates from flow units and is modulated by the energy distribution of flow units, and the density and distribution of flow units can effectively regulate the β-relaxation behavior. The results provide a better understanding of the structural origin of β-relaxation and also afford a method for designing metallic glasses with obvious β-relaxation and better mechanical properties.

  1. Revealing β-relaxation mechanism based on energy distribution of flow units in metallic glass.

    PubMed

    Lu, Z; Shang, B S; Sun, Y T; Zhu, Z G; Guan, P F; Wang, W H; Bai, H Y

    2016-04-14

    The β-relaxation, which is the source of the dynamics in glass state and has practical significance to relaxation and mechanical properties of glasses, has been an open question for decades. Here, we propose a flow unit perspective to explain the structural origin and evolution of β-relaxation based on experimentally obtained energy distribution of flow units using stress relaxation method under isothermal and linear heating modes. Through the molecular dynamics simulations, we creatively design various artificial metallic glass systems and build a direct relation between β-relaxation behavior and features of flow units. Our results demonstrate that the β-relaxation in metallic glasses originates from flow units and is modulated by the energy distribution of flow units, and the density and distribution of flow units can effectively regulate the β-relaxation behavior. The results provide a better understanding of the structural origin of β-relaxation and also afford a method for designing metallic glasses with obvious β-relaxation and better mechanical properties.

  2. ERD studies of D-ion depth distributions after implantation into some pure metals and alloys

    NASA Astrophysics Data System (ADS)

    Didyk, A. Yu.; Wiśniewski, R.; Wilczynska, T.; Kitowski, K.; Hofman, A.

    2012-01-01

    This paper presents a report on experimental results of depth distributions of deuterium ions implanted with 25 keV energy at a fluence interval of (1.2-2.3) × 1022 m-2 into samples of pure metals (Cu, Ti, Zr, V, Pd) and diluted Pd alloys (Pd-Ag, Pd-Pt, Pd-Ru, Pd-Rh). The post-treatment depth distributions of deuterium and hydrogen atoms were measured within a few hours after implantation with the use of elastic recoil detection (ERD) analysis. After three months the measurements were repeated. The comparison of the obtained results in both series of studies allowed us to make an important observation of the desorption rates of implanted deuterium atoms from pure metals and diluted Pd alloys. The maximum measured concentrations of deuterium atoms in pure Zr and Ti foils with relatively small desorption rate of deuterium atoms within three months after implantation were observed. Also a very high spreading of deuterium atom distributions was observed in all the measured pure metals and alloys. It can be explained by the large diffusion coefficients of deuterium and extremely fast kinetics.

  3. Ultraviolet to near-infrared spectral distributions of star-forming galaxies: Metallicity and age effects

    NASA Technical Reports Server (NTRS)

    Storchi-Bergmann, Thaisa; Calzetti, Daniela; Kinney, Anne L.

    1994-01-01

    Spectral distributions from the UV to the near-IR of a sample of 44 star-forming galaxies are used to calculate the metallicity (O/H), star-formation rate (SFR) and age of the starbursts. The oxygen abundance covers the range 8.3 less than O/H less than 9.4 and nitrogen (N) is found to be mostly a product of secondary nucleosynthesis for O/H greater than 8.4. Due to its secondary origin, N/O ratios up to approximately equals 4 times the solar value can be obtained for metal-rich starbursts. The SFR ranges 0.01 to 100 solar mass/year. The lower metallicity galaxies seem to be experiencing an instantaneous burst of star formation, with ages ranging from under 5 x 10(exp 6) to 10(exp 7) yr. The highest metallicity galaxies are most probably experiencing a continuous burst. Correlations between the calculated quantities and several spectral features are investigated. We found a highly significant correlation between the equivalent width W(C IV lambda 1550)-a stellar (absorption) feature- and the oxygen abundance of the emitting gas (O/H). Thus we show for the first time that the stellar metallicity is well correlated with the gas metallicity in star-bursting galaxies. The equivalent width W(Si IV lambda 1400) and the emission line ratio (N II) lambda lambda 6548.84/H(sub alpha) also correlate well with O/H, and all three features can be used as metallicity indicators for star-forming galaxies. The continuum color between lambda 1400 and lambda 3500 (C(14 - 35)) is shown to correlate with O/H, although it is better correlated with E(B - V). It was not possible to disentangle the metallicity from the reddening effect in C(14- 35). We estimate that the reddening affecting the UV continuum is about half the one derived from the Balmer decrement of the emitting gas. The SFR correlates well with the galaxy luminosity and there is no dependence of the continuum color on the SFR. The higher metallicities are only found in the more luminous galaxies, while low metallicities are

  4. Single Particle ICPMS for Characterizing Metal-based Nanoparticles and Monitoring Transformation Processes in Surface Water

    EPA Science Inventory

    Engineered metal-based nanomaterials will likely be used in increasing quantities in consumer and industrial products. These may be introduced into surface waters by a variety of paths depending on usage. Other naturally occurring and anthropogenic particles containing these met...

  5. Single Particle ICPMS for Characterizing Metal-based Nanoparticles and Monitoring Transformation Processes in Surface Water

    EPA Science Inventory

    Engineered metal-based nanomaterials will likely be used in increasing quantities in consumer and industrial products. These may be introduced into surface waters by a variety of paths depending on usage. Other naturally occurring and anthropogenic particles containing these met...

  6. Critical metals in manganese nodules from the Cook Islands EEZ, abundances and distributions

    USGS Publications Warehouse

    Hein, James R.; Spinardi, Francesca; Okamoto, Nobuyuki; Mizell, Kira; Thorburn, Darryl; Tawake, Akuila

    2015-01-01

    Compiled data from a series of four cruises by the Japan International Cooperation Agency and the Mining agency of Japan from 1985 to 2000 were used to generate a map that defines the statistical distribution of nodule abundance throughout the EEZ, except the Manihiki Plateau. The abundance distribution map shows a belt of high nodule abundance (19–45 kg/m2) that starts in the southeast corner of the EEZ, runs northwest, and also bifurcates into a SW trending branch. Small, isolated areas contain abundances of nodules of up to 58 kg/m2. Six ~ 20,000 km2 areas of particularly high abundance were chosen to represent potential exploration areas, and maps for metal concentration were generated to visualize metal distribution and to extrapolate estimated metal tonnages within the six sites and the EEZ as a whole. Grades for Mn, Cu, and Ni are low in CIs nodules in areas of high abundance; however, Ti, Co, and REY show high contents where nodule abundances are high. Of the six areas identified to represent a range of metal contents, one at the northern end of the N-S abundance main belt optimizes the most metals and would yield the highest dry metric tons for Mn (61,002,292), Ni (1,247,834), Mo (186,166), V (356,247), W (30,215), and Zr (195,323). When compared with the Clarion–Clipperton Zone, the CIs nodules show higher nodule abundances (> 25 kg/m2 over ~ 123,844 km2), and are more enriched in the green-tech, high-tech, and energy metals Co, Ti, Te, Nb, REY, Pt, and Zr. The CIs EEZ shows a significant resource potential for these critical metals due to their high prices, high demand, and the high nodule abundance, which will allow for a smaller footprint for a 20-year mine site and therefore smaller environmental impact.

  7. Non-canonical distribution and non-equilibrium transport beyond weak system-bath coupling regime: A polaron transformation approach

    NASA Astrophysics Data System (ADS)

    Xu, Dazhi; Cao, Jianshu

    2016-08-01

    The concept of polaron, emerged from condense matter physics, describes the dynamical interaction of moving particle with its surrounding bosonic modes. This concept has been developed into a useful method to treat open quantum systems with a complete range of system-bath coupling strength. Especially, the polaron transformation approach shows its validity in the intermediate coupling regime, in which the Redfield equation or Fermi's golden rule will fail. In the polaron frame, the equilibrium distribution carried out by perturbative expansion presents a deviation from the canonical distribution, which is beyond the usual weak coupling assumption in thermodynamics. A polaron transformed Redfield equation (PTRE) not only reproduces the dissipative quantum dynamics but also provides an accurate and efficient way to calculate the non-equilibrium steady states. Applications of the PTRE approach to problems such as exciton diffusion, heat transport and light-harvesting energy transfer are presented.

  8. Electrospray ionization Fourier transform ion cyclotron resonance mass spectrometric analysis of metal-ion selected dynamic protein libraries.

    PubMed

    Cooper, Helen J; Case, Martin A; McLendon, George L; Marshall, Alan G

    2003-05-07

    The application of electrospray ionization (ESI) Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry to the investigation of the relative stabilities (and thus packing efficiencies) of Fe-bound trihelix peptide bundles is demonstrated. Small dynamic protein libraries are created by metal-ion assisted assembly of peptide subunits. Control of the trimeric aggregation state is coupled to stability selection by exploiting the coordination requirements of Fe(2+) in the presence of bidentate 2,2'-bipyridyl ligands covalently appended to the peptide monomers. At limiting metal-ion concentration, the most thermodynamically stable, optimally packed peptide trimers dominate the mass spectrum. The identities of optimally stable candidate trimers observed in the ESI FT-ICR mass spectra are confirmed by resynthesis of exchange-inert analogues and measurement of their folding free energies. The peptide composition of the trimers may be determined by infrared multiphoton dissociation (IRMPD) MS(3) experiments. Additional sequence information for the peptide subunits is obtained from electron capture dissociation (ECD) of peptides and metal-bound trimers. The experiments also suggest the presence of secondary structure in the gas phase, possibly due to partial retention of the solution-phase coiled coil structure.

  9. Field Performance of Three-Phase Amorphous Metal Core Distribution Transformers at Pearl Harbor, Hawaii

    DTIC Science & Technology

    1990-08-01

    power gerwation) ;2 2,n~tr-octcn mathodo and mztcr1,es iinolug carro -ion 30 Controls and electrical conservation (eectrcal systes. Control, coatings...Eng.rieen Teat Faclftles power systems. solar systems. wind systems, energy storage 7 F~Re Pr*vn+nton and c;ontrol systems) 3A.1untsmJ, *scnocgy 33

  10. Distribution of metals and brominated flame retardants (BFRs) in sediments, soils and plants from an informal e-waste dismantling site, South China.

    PubMed

    Wang, Junxia; Liu, Lili; Wang, Jinfu; Pan, Bishu; Fu, Xiaoxu; Zhang, Gang; Zhang, Long; Lin, Kuangfei

    2015-01-01

    Brominated flame retardants (BFRs, including polybrominated diphenyl ethers (PBDEs) and tetrabromobisphenol-A (TBBPA)) and metals (Cu, Zn, Pb, Cd, Ni, Hg and As) in sediments, soils and herb plants from unregulated e-waste disposal sites were examined. The metal concentrations, ∑PBDE and TBBPA concentrations in all samples from the examined e-waste dismantling sites were relatively high in comparison with those of rural and urban areas around the world. The PBDE and TBBPA levels in soils significantly decreased with increasing distance from the e-waste dismantling sites, indicating that PBDEs and TBBPA had similar transport potential from the e-waste dismantling process as a point source to the surrounding region. BDE-209 and TBBPA predominated in all samples, which is consistent with the evidence that the deca-BDE and TBBPA commercial mixtures were extensively used in electronic products. Metals, PBDEs and TBBPA displayed significant positive correlations with TOC, whereas the correlations with pH were insignificant, indicating that TOC was a major factor governing the spatial distribution, transportation and fate in sediments and soils. A significant relationship between log-transformed metals and BFR concentrations indicated common pollution sources. Moreover, cluster analysis and principal component analysis further confirmed that the metals and BFRs had a common source, and penta- and deca-BDE commercial products may be two sources of PBDEs in this region.

  11. Characterization and spatial distribution of heavy metals in sediment from Cedar and Ortega rivers subbasin.

    PubMed

    Ouyang, Ying; Higman, John; Thompson, Jeanne; O'Toole, Tim; Campbell, Dean

    2002-01-01

    The Cedar and Ortega rivers subbasin is a complex environment where both natural and anthropogenic processes influence the characteristics and distributions of sediments and contaminants, which in turn is of importance for maintenance, dredging and pollution control. This study investigated the characteristics and spatial distribution of heavy metals, including lead (Pb), copper (Cu), zinc (Zn) and cadmium (Cd), from sediments in the subbasin using field measurements and three-dimensional kriging estimates. Sediment